ZOONOMIA; 
OR) 
THE LAWS 
OF 
ORGANIC LIFE. 
IN THREE PARTS. 
Ry ERASMUS DARWIN, M.D.F.R.S. 
AUTHOR of the BOTANIC GARDEN, PIIYTOLOGIA, &C. 
Principle) ccelum, ac terras, campofque liquentes, 
Lucentemque globum lunae, titaniaque aftra, 
Spiritus intiis alit, totamque infufa per artus 
Mens agitat molem, et magno fe corpora mifcet. 
Viro. TEn. vi. 
Earth, on whofe lap a thoufand nations tread, 
And Oceait, brooding his prolific bed, 
Night's changeful orb, blue pole, and filvery zones, 
Where other worlds encircle other funs, -- 
One mind inhabits, one diffufive Soul . | I? 12 
Wield: the large limbs, and mingles with-ehe wrw<v 
COMPLETE IM TWO VOLUMlL 
Vol. I. 
Second American, from the third London Edition, corrected by the Author. 
Printed at Bofton, by d. CARtisisp 
For THOMAS and ANDREWS. 
Sold at their Bookftore, No. 45, Newbury Street; by I. Thomas, Worcefter; and 
by Thomas & Thomas, Walpole, N. H.-Sold alfo by T. & J. Swords. 
New York ; Whiting, Leavenworth GT Whiting, Albany; 
O> Penniman S' Co. Troy ; and Thomas, An* 
drews & Butler, Baltimore. v 
Feb. 1803. DEDICATION. 
To the candid and ingenious Members 
of the College of Phyficians, of the Royal 
Philofophical Society, of the Two Uni- 
verfities, and to all thofe, who ftudy the 
Operations of the Mind as a Science, or 
who praftife Medicine as a Profeffion, 
the fubfequent Work is, with great ref- 
peft, infcribed by the Author. 
Derby, May i, 1794. T O 
ERASMUS DARWIN, 
ON HIS WORK ENTITLED 
Z O O N O M I A. 
By DEWHURST BILSBORROW. 
Hail to the Bard ! who fung, from Chaos hurl'd 
How funs and planets form'd the whirling world; 
How fphere on fphere Earth's hidden ftrata bend, 
And caves of rock her central fires defend ; 
Where gems new-born their twinkling eyes unfold, 5 
And young ores Ihoot in arborefcent gold. 
How the fair Flower, by Zephyr woo'd, unfurls 
Its panting leaves, and waves its azure curls; 
Or fpreads in gay undrefs its lucid form 
To meet the fun, and fhuts it to the ftorm; 10 
While in green veins impaflion'd eddies move, 
And Beauty kindles into life and love. 
How the firft embryon fibre, fphere, or cube. 
Lives in new forms,-a line,-a ring,-a tube; 
Clofed in the womb with limbs unfinilh'd laves, 
Sips with rude mouth the falutary waves; 
Seeks round its cell the fanguine ftreams, that pafs, 
And drinks with crimfon gills the vital gas; 
Weaves with foft threads the blue meandering vein, 
The heart's red concave, and the filver brain; 30 
Leads the long nerve, expands the impatient fenfe, 
And clothes in filkcn Ikin the nafeent Ens. 
Erewhile, emerging from its liquid bed. 
It lifts in gelid air its nodding head; 
The light's firft dawn with trembling eyelid hails, aj 
With lungs untaught arrefts the balmy gales; 
Tries its new tongue in tones unimown, and hears 
The ftrange vibrations with unpraeftifed ears; 
Seeks with fpread hands the bofom's velvet orbs, 
With dofing lips the milky fount abforbs; 30 
And, as comprefs'd the dulcet ftreams diftil, 
Drinks warmth and fragrance from the living rill 
Eye* VI 
TO ERASMUS DARWIN. 
£ye* with mute rapture every waving line. 
Prints with adoring kifs the Paphian flirine, 
And learns ere long, the perfedi form confefs'd, 33 
Ideal Beauty from its mother's breaft. 
Now in ftrong lines, with bolder tints defign'd, 
You Iketch ideas, and portray the mind; 
Teach how fine atoms of impinging light 
To ceafelefs change the vifual fenfe excite : 40 
While the bright lens collects the rays, that fwerve. 
And bends their focus on the moving nerve. 
How thoughts to thoughts are link'd with viewlefs chains, 
Tribes leading tribes, and trains purfuing trains ; 
With fhadowy trident how Volition guides, 45 
Surge after furge, his intellectual tides; 
Or, Queen of Sleep, Imagination roves 
With frantic Sorrows, or delirious Loves. 
Go on, O Friend ! explore with eagle-eye; 
Where wrapp'd in night retiring Caufes lie: 50 
Trace their flight bands, their fecret haunts betray, 
And give new wonders to the beam of day ; 
Till, link by link with ilep afpiring trod, 
You climb from Nature to the throne of God. 
So faw the Patriarch with admiring eyes 55 
From earth to heaven a golden ladder rile ; 
Involv'd in clouds tjie myftic fcale afeends, 
And brutes and angels crowd the diftant end*. 
Trin, Qou Cambridge, Jan. 1,1794. 
REFERENCES. 
Beanie Garden, Part I. 
Line r. Canto I. 1. 105. 
, 3. IV. 1. 402. 
4. I. 1 140. 
j. III. 1. 401. 
8. IV I. 45*. 
« Q. I- I 14- 
Line 18. Seft. XVI. 2. and XXXV1H. 
26. XVI. 4. 
30. XVI. 4. 
36. xvi. 6. 
38. III. and VIL 
43- X. 
44. XVIII. 17. 
45. XVII. 3. 7. 
47. XVIII. 8. 
50. XXXIX. 4 8. 
51. XXXIX the Motte,. 
<;4( XXXIX,. 8. 
Zaonomia. 
i», Se«a. XIII. 
. 13. --XXXIX 4. 1. PREFACE. 
The purport of the following pages is an endeavour 
to reduce the fads belonging to Animal Life into 
clalfes, orders, genera, and fpecies; and, by comparing 
them with each other, to unravel the theory of difeafes. 
It happened, perhaps unfortunately for the inquirers in* 
to the knowledge of difeafes, that other fciences had re* 
ceived improvement previous to their own ; whence, in* 
ftead of comparing the properties belonging to animated 
nature with each other, they, idly ingenious, bufied them- 
felves in attempting to explain the laws of life by thofe 
of mechanifm and chemiftry ; they confidered the body 
as an hydraulic machine, and the fluids as palling through 
a feries of chemical changes, forgetting that animation 
was its eflential charaderiftic. 
The great Creator of all things has infinitely diver* 
fified the works of his hands, but has at the fame time 
ftamped VIII 
PREFACE. 
ftamped a certain fimilitude on the features of nature, 
that demonftrates to us, that the whole is one family of 
one parent. On this fimilitude is founded all rational 
analogy ; which, fo long as it is concerned in compar- 
ing the eflential properties of bodies, leads us to many 
and important difeoveries; but when with licentious ac- 
tivity it links together objects, otherwife difeordant, by 
fome fanciful fimilitude ; it may indeed celled orna- 
ments for wit and poetry, but philofophy and truth re- 
coil from its combinations. 
I 
The want of a theory, deduced from fuch ftriet anal- 
ogy, to conduct the practice of medicine, is lamented by 
its profeffors; for, as a great number of unconnected 
fads are difficult to be acquired, and to be reafoned from, 
the art of medicine is in many inflances lefs efficacious 
under the direCtion of its wife ft practitioners; and by 
that bufy crowd, who either boldly wade in darknefs, or 
are led into endlefs error by the glare of falfe theory, it 
is daily praCtifed to the deRruCtion of thoufands; add 
to this the unceafing injury which accrues to the public 
by the perpetual advertifements of pretended noftrums; 
the minds of the indolent become fuperftitioufly fearful 
of difeafes, which they do not labour under ; and thus 
become the daily prey of fome crafty empyric. 
A theory founded upon nature, that Ihould bind to- 
gether the fcattered fads of medical knowledge, and con- 
verge into one point of view the laws of organic life, 
would thus on many accounts contribute to the intereft 
of focietv. It would capacitate men of moderate abili- 
ties PREFACE. 
IX 
ties to pta&ife the art of healing with real advantage to 
the public; it would enable evety one of literary ac- 
quirements to diftinguifh the genuine difciples of medi- 
cine from thofe of boaftful effrontery, or of wily addrefs ; 
and would, teach mankind in fome important fituations 
the knowledge of th cmfelves. 
There arefome modern practitioners, who declaim againft 
medical theory in general, not confidering that to think 
is to theorize; and that no one can direCl a method of 
cure to a perfon labouring under difeafe without think- 
ing, that is, without theorizing • and happy therefore 
is the patient, whofe phyfician poffeffes the belt theory. 
The words idea, perception, fenfation, recolle&ion, 
fuggeftion, and affociation, are each of them ufed in this 
treatife in a more limited fenfe than in the writers of met- 
aphyfic. The author was in doubt, whether he ihould 
rather have fubftituted new words inftead of them ; but 
was at length of opinion, that new definitions of words 
already in ufe would be lefs burthenfome to the memory 
of the reader. 
A great part of this work has lain by the writer above 
twenty years, as fome of his friends can teftify: he had 
hoped by frequent revifion to have made it more worthy 
the acceptance of the public ; this however his other 
perpetual occupations have in part prevented, and may 
continue to prevent, as long as he may be capable of re- 
vifing it; he therefore begs of the candid reader to ac- 
cept of it in its prefent date, and to excufe any in- 
V°Lt h k accuracies X 
PREFACE. 
accuracies of expreflion, or of conclufion, into which 
the intricacy of his fubjed, the general imperfedion 
of language, or the frailty he has in common with other 
men, may have betrayed him; and from which he has 
not the vanity to believe this treatife to be exempt. 
PREFACE PREFACE 
T O 
THE THIRD LONDON EDITION. 
The Reader fhould be apprized, that many new pages 
are interfperfed in this edition, which confift of practical 
and theoretical obfervations, as the whole articles on He- 
micrania idiopathica, retroverfio uteri, aneurifma, and 
the appendix to the fedion on Generation, beginning at 
No. 8. as well as the diftindion between philofophy 
and fophiftry in Sed XV. i. 5. and the Ratiocinatio 
verbofa, verbal reafoning, in Clafs III. 2. 2. 3. and fome 
others. 
Derby, Jan. 1, 1801. 
In the former editions of this work the Materia 
Medica [which forms Part III.] was placed after the 
fecond part, or the clafles of difeafes, but to preferve the 
more equal fize of the volumes, in this odavo edition, the 
publilher has placed it, with the affent of the author, af- 
ter the firft part. 
CONTENTS. CONTENTS. 
PART I. 
Sect. I. Of Motion. ------ i 
II. Explanations and Definitions. 3 
III. The Motions of the Retina demonftrated by 
Experiments. ----- 8 
IV. Laws of Animal Caufation. 20 
V. Of the four Faculties or Motions of the Sen- 
forium. - - - - - - 21 
VI. Of the four Clafles of Fibrous Motions. - 23 
VII. Of Irritative Motions. - - - - 25 
VIII. Of Senfitive Motions. - - - - • 29 
IX. Of Voluntary Motions. - - - 31 
X. Of Aflbciate Motions. 34 
XI. Additional Obfervations on the Senforial 
Powers. 37 
XII. Of Stimulus, Senforial Exertion, and Fibrous 
Contraction. 43 
XIII. Of Vegetable Animation. - - - 73 
XIV. Of the Production of Ideas. - - - 79 
XV. Of the Clafles of Ideas. - - - 95 
XVI. OflnftinCt. - - - - - 101 
XVII. The Catenation of Animal Motions. - 143 
XVIII. Of Sleep. - - - - - - 153 
XIX. Of Reverie. - - - - - 170 
XX. Of Vertigo. - - - - - 175 
XXL Of Drunkennefs. - - - - 191 
XXII. Of Propenfity to Motion. Repetition. Im- 
itation. - - - - - -198 
XXIII. Of the Circulatory Syftem. - - 206 
XXIV. Of the Secretion of Saliva, and of Tears. 
And of the Lachrymal Sack. - - 212 
XXV. Of the Stomach and Inteftines. - - 217 
XXVI. Of the Capillary Glands, and of the Mem- 
branes. ----- 226 
XXVII. Of Haemorrhages. - - - - 229 
XXVIII. The Paralylis of the LaCteals. - - 234 
Sect. XIV 
CONTENTS. 
Page. 
Sect. XXIX. The Retrograde motions of the abforbent 
Vefiels. - - - - - 238 
XXX. The Paralyfis of the Liver and Kidneys. - 272 
XXXI. Of Temperaments. - - - 277 
XXXII. Difeafes of Irritation. - - - 282 
XXXIII.. ofSenfation. - - - 305 
XXXIV. of Volition. - - - - 324 
XXXV. of Aflbciation. - - 343 
XXXVI. The Periods of Difeafes. - - 352 
XXXVII. Of Digeftion, Secretion, Nutrition. - 36a 
XXXVIII. Of the Oxygenation of the Blood in the 
Lungs and Placenta. - - _ 366 
XXXIX. Of Generation. - - - - 373 
XL. Of Ocular Spe&ra. - - _ 443 
[Part II. forms the second Volume.] 
PART III. 
ARTICLES OF THE MATERIA MEDICA. 
Page- 
Art. I. Nutrentia. 5 
II. Incitantia. 19 
III. Secernentia. - - - - 31 
IV. Sorbentia. - - - - 42 
V. Invertentia. - - 65 
VI. Revertentia. - - - - 70 
VII. Torpentia. - - ' - - 73 
INTRODUCTION INTRODUCTION 
TO THE 
AMERICAN EDITION. 
contents of the introduction. 
Object of tie frjl part of the Zoonomia. Arrangement of living motions* 
Functions referable to each of thefe. Clajffication of animated action 
under four heads. Influence of JUmuli in fujlaining life. Comparifon 
of Dr. Darwin's doctrine of Jlimulus and exertion with the Brunonian 
Elements. Great refemblance acknowledged by the former. Which of 
them was indebted to the other ? The two authors efpoufe fimilar funda- 
mental principles. Examination of the Jlander that Brown's doctrine 
was but a revival of the opinions of the ancient Methodic Sefl. Hijlc- 
ry °f ^at fe&' branch of the Epicureans. Sketch of the Epicurean 
phtlofophy. Application of this to medicine. Reafoning wholly mechan- 
ical. Hi/lory of the opinions concerning life fuperadded to mechanifm, 
from Hippocrates to Cullen. How far the lattef had proceeded. Mer- 
its of Brown. AbjlraR of the frjl edition of his Elementa, publifhed in 
1780, and now very rare. Review of his fecond edition in 1784. 
The Engljh work a mere tranjlation of this. Epitome of the Bruno- 
nian DoRrine. Very different from the notions of Themifon and Thef- 
falus. Defers in Brown's fyjlem. Room for improvements. Great 
amendments made by various perfons. Introduction of chemical princi- 
ples and modes of reafoning. Infuffcient to explain the phenomena of 
life. Laudable attempt of Dr. Darwin to invejligate thofe laws which 
neither mechanifm nor chemiftry can explain. ObjeR of the fecond part 
to form a nofology, or catalogue of difeafes, by a natural clajfftcation, 
founded on their prffximate caufes. 
AN attempt has been made in the firft part of this work to in* 
veftigate the complex laws of animal caufation. Thefe are dc* 
duced from the contractions and relaxations performed by the living 
fibres, which conftitute the mufcles and organs of fenfe. Fibrous con* 
tractions feem to conftitute all the functions of animated bodies, 
and indeed all we know both phifiologically and medically con* 
cerning XVI 
INTRODUCTION TO THE 
cerning life and its functions. They are arranged into four claff- 
es of motions, which form the foundation of all juft nofology and 
practice, as detailed in the fecond great divifion of the Zoonomia. Vi- 
tal motions are thus called irritative, fenjitive, voluntary, and ajfociated, 
according as the parts of the body in which they exift are endowed 
with irritability, fenfation, volition, or fympatby. This quadruple allot- 
ment of fun&ions forms a ftrong and peculiar character of the follow- 
ing work. And the diftribution of the almoft endlefs variety of ani- 
mated phenomena into this fourfold and lucid arrangement, is a clear 
proof of the difcriminating and generalizing mind of the author. 
But in all thefe conditions of the fyftem, whether influenced by the 
vis infita or the vis nervea, by voluntary or fympathetic energy, the fen- 
forial powers are fuftained by the unceafmg operation of stimulants. 
The theory of thefe is contained in the twelfth chapter of the firft part, 
and exhibits very advantageoufly the doftrine of ftimulus, and exertion, 
or as it has been more generally called, excitement. 
There is a ftriking analogy between thefe fundamental doctrines of 
Dr. Darwin and thofe contained in Dr. Brown's Elements of Medicine. 
Our author was aware of this, and to guard himfelf againft the impu- 
tation of having borrowed Brown's ideas without acknowledgment, or 
of being merely his imitator, he obferves that " the coincidence of 
" fome parts of this work with correfpondent deductions in the Bru- 
" nonian Elementa Medicine, a work (with fome exceptions) of great 
" genius, muft be confidered as confirmations of the truth of the 
" theory, as they were probably arrived at by different trains of rea- 
" foning." 
In refpeft to originality, there is great difficulty in fettling claims. 
In this cafe however, there is not even a fufoicion that Brown derived 
any thing from Darwin. Both might indeed have come to fimilar 
conclufions, by the independent exercife of their reafon, without any 
communication or intercourfe. And yet, an impartial obferver, prone 
neither to obloquy nor flattery, would not forfeit his candour in fuf- 
peCting that a writer of Darwin's acutenefs might have gathered fome- 
thing from Brown, who published fourteen years before him. 
Confidering the Brunonian and Darwinian fyftems as refting upon 
the fame pillars, it appears to me there may be both ufefulnefs and cu- 
riofity in fearching and digging about the ground on which they ftand. 
In performing this talk, it has been expefted there Ihould be a ftate- 
ment (hewing how far thefe doftrines of the Scottish and Englilh phy- 
ficians are themfelves novel or modern, or whether they are both of 
the old fchool and derived from remote and ancient fources. 
By deciding in favour of their modernity, it will be likewife expect- 
ed that a view Ihould be given of the Brunonian fyftem, that it may 
be compared with the cotemporary doCtrines of Cullen and Darwin. 
In this comparifon, it will be found, that Brown's merit is very con- 
fpicuous. The three diftinguilhed authors have finiftied their earthly 
career, and they and their writings may now be confidered without 
envy or partiality. To thofe who are curious to trace the progrefs 
of thefe opinions, which exert fuch extenfive dominion over the mind, 
thefe AMERICAN EDITION. 
XVII 
thefe introdu&ory remarks may perhaps afford Tome gratification. 
Others, who poffefs not the tafte or leifure for fuch enquiries, may pais 
them over, and in the progrefs of obfervation and experiment in phyfics, 
within a few years, fuch a number of new and important fafts have 
been brought to light, that many philofophers have believed the peo- 
ple of the prefent day were poffeffed of a great deal more knowledge 
than the moderns of the three laft centuries, or their Ancient prede- 
ceflors. 
This opinion, in particular, has been deemed well founded, and true 
in its refpeft to medicine, which, at this time, is not only confidered 
fufceptible of new expofitions and interpretations, but of being great- 
ly improved and enlarged, both in theory and praftice. And although 
among thofe who think thus are reckoned moft of the original and clear 
lighted geniufes of our time, yet there are not wanting fome, and thofe 
men of talents and reputation too, who are in the habit of thinking, if 
the ancients knew not quite aS much as ourfelves, yet their writings 
contain the leading hints, or great outlines of almoft every thing dif- 
coverable, either dire&ly expreffed, or lignified in allegorical terms. 
This literary fuperftititon has been carried a great way ; and if it had 
flopped at declaring the Iliad the beft of poflible poems, or the Phil- 
lilies the moft finilhed of the rhetorical produftious, I Ihould not at 
this time have troubled myfelf to contradict it. But when thefe 
euthufiaftic admirers of antiquity declare, that, in matters of feience as 
well as of letters, the fubjefts of enquiry have been exhaufted two 
thoufand years ago, and that no idea can be ftarted which is not an 
imitation of fomething that a Greek or a Roman, or fome body elfe, 
had thought before, I own 1 am a little difpofed to believe their 
affertions are grounded neither in truth nor in the nature of things. 
For why muft we refort to the Platonists, Stoics, and Peripa- 
tetics, for doctrines which the Academy, the Porch, and the Ly- 
ceum never knew ? 
Thefe remarks are made in confequence of an opinion propagated 
and believed by fome, that a certain method of reafoning upon medical 
fubje&s, and of medical pra&ice introduced now of late as many be- 
lieve, which are already pretty well eftablilhed, and acquiring rapidly 
more and more adherents, are in faff but a revival and new modelling 
of the opinions and procedure of the Methodic Sect, founded by 
Asclepiades, the cotemporary of Mithridates and Crassus. 
In order to know whether this opinion is well founded, 1 {hall en- 
quire what the philofophy of the Methodic Sect was. 
Its founder, Asclepiades, adopted that philofophy, whofe foun- 
dation had been laid by Anaxagoras, Empedocles, and Heracli- 
tus, and which was afterwards wrought up into the Atomic by 
Leucippus, and Democritus, of the Eleatic Suit ; who, rejecting all 
metaphyfical explanations of the caufesof things, undertook the inter- 
preting nature, from the laws of matter and motion. This was after- 
wards commented upon, enlarged and adorned by Epicurus, lb as 
to form, what was afterwards called the Epicurean Pbilojophy. What 
the details of this are, may be feen in Diogenes Laertius, in 
ot. I. c Brucker XVIII 
INTRODUCTION TO THE 
Brucker and his tranflator Enfield, as well as in the poem of ..Lu- 
cretius, who has confcfledly attempted a poetical difplay of thefe 
very doctrines. A general view, comprifing a mere (ketch of the fyf- 
tem of this AvT^/^k?*; or felf-taUght man, as he called himfelf as far 
as connected with the prefent fubjeft, is all I (hall offer here. An 
Epicurean would explain himfelf thus :-" It is clear, from the chang- 
" es which natural bodies undergo, that there is a perpetual formation 
" and deftruftion of them going on ; there muft then exift matter of 
" which thefe things are formed, and into which they are refolved ; 
" and hence proceeds the conclufion which is the ground-work of the 
" fyftern, that a thing can neither be made out of nothing, nor reduced 
" to nothing. tl Nullam rem c nibilo gigni divinitus unquam." The 
" univerfe, therefore, as to its conftituent atoms or particles, was al- 
il ways as it is at prefent ; and confequently matter is eternal. The 
" workman cannot perform any thing without materials ; and thefe 
" felf-exiftent materials, in the decay and renovation they undergo, ac- 
" count for the phenomena of nature and of art. If things were cre- 
" ated out of nothing, then every kind fhould proceed from each, and 
" the greateft irregularity enfue ; men (liould be produced in the fea, 
" fifties on the land, and cattle in the clouds ; generation would be ufe- 
" Jefs. and food unneceffary : if they returned to nothing, then, in the 
" courfe of paft ages, through wafte, confumption, and lofs, much 
" muft have tanilhed to non-exiftence, and have been completely anni- 
" hilated. But neither of thefe fuppofitions is true, fince out of the 
" wreck or ruin of one being or exiftence, nature, we know, without an 
11 aft of creation or annihilation, can work up the old materials into a 
" new fabric. 
" All existences in nature are referable to two kinds, i. Bodies ; 
il and, 2. The inane, or void in which they exift. 
" Our fenfes fatisfy us of the exiftence of bodies, as alfo do their 
aftions, pafiions, and refilling powers; particularly as they operate 
" upon each other, and upon our touch : 
" Tangere enim et tangi nifi corpus nulla poteft res."-I.ucret. 
" For nothing but a body can touch or be touched." 
" From the exiftence and motion of bodies is inferred the exiftence 
" of fpace ; and the effeft of bodies operating upon each other is de- 
" nominated " an eventand if there was not a void there would not 
" be a poflibility of motion ; for if a plenum exifted, then every portion 
" of fpace being clofely impafted and wedged with folidity, the mod 
" uniform reft and dead ftillnefs would pervade the whole of nature. 
" As to bodies, they either confift of elementary atoms, or of fub- 
" fiances formed from thefe ; and thefe primordial particles, notwith- 
(landing fome appearances to the contrary, arc fimple, folid, and 
" indivifible. 
" Sunt igitur solida, ac fine inani corpora prima."-I.ucret. 
" Therefore Elementary bodies are folid and deftitute of vacuity." 
" All AMERICAN EDITION. 
XIX 
" All thefe atoms poffefs the fame general properties, and do not 
" differ from each other in any effential refpeft. Though, from their 
" different operations upon the fenfes, is inferred a difference among 
" them as to fize, ihape, and heavinefs. Their figures, in particlur, 
" are varied in an endlefs manner, fo as to take on every mechanical 
" form : but in all thefe cafes they are Hill infrangible and incapable 
" of farther divifion. 
" Each atom contains, within itfelf, an aftive energy, or internal 
" force, by which it is either conftantly in motion, or making an effort 
" to move ; and this is denominated gravity. rl hefe atoms, impelled 
" by gravity through void [pace in curvilinear courfes, ftrike againft 
" each other, exercife repelling powers, and produce vibration or agi- 
" tation ; and as this gravitating power is effential to matter, it can 
" never be iua&ive, but mud be always at work, and has been lo from 
" eternity. 
" Every compound body, being made up of individual atoms, there- 
fore poffeffes the united energy of them all, which energy is the Joie 
" agent in nature ; but by reafon of their different figures, their 
" varied magnitudes, and particular lituations, it is varioufly modifi- 
" ed ; as when the atoms are hooked or rough, motion will be retarded 
11 among them, and be facilitated when they are round and fmooth, as 
" in the principles of fire and animation. Bodies thus being comjxif- 
" ed of atoms, derive their actions from the energy inherent in and 
" proceeding from thefe atoms. 
" All alterations happening in bodies, whether in their Ihape, hard- 
" nefs, fweetnefs, &c. are afcribable to the change taking place in the 
" arrangement, difpofition, &c. of the conftituent particles ; and thus 
" porofity, tranfpare;ncy, elafticity, malleability, &c. are to be account- 
" ed for in the fame way. Gravity being an effential property of fnat- 
" ter, all corpufcules, and all bodies formed of them, mult be heavy. 
" Thus, from thefe properties of bodies, their feveral combinations 
" and mechanical operations, arife other more complex phenomena, 
" referable however to the principle of motion, fuch as the heating of 
" bodies from the influx of foft, round and fmooth particles; the cool- 
'' ing of them from the ingrefs of atoms of oppolite and irregular 
" figures; even fenfations, both of the pleafurable and painful kinds, 
" motion, reft, and time itfelf, are contingences to bodies. In fliort, 
" the whole phenomena of the production, growth, nutrition, decline, 
" and diffolution of bodies, is to be afcribed to an alteration of ar- 
" rangement in the particles, and to their addition or fubtraCtion. 
" Minerals, plants, and animals were thus produced in the beginning, 
" according to thefe mechanical laws of matter and motion, and fo was 
" the world they compofe and inhabit. They continue to propagate 
" their kinds in regular ways, becaufe nature has become accullomed,by 
" habit, to produce them in an order fo uniform as to look like defign. 
" The eye, however, was not made for feeing, nor the ear for hearing ; 
" but having been accidentally formed in fuch a way as to anfwer 
" thefe purpofes, the fentient principle within, which is co-exiftent 
" with XX 
INTRODUCTION TO THE 
with the organization, finding them fit for the purpofes of fight and 
" hearing, makes ufe of them accordingly. 
" Senfation, proceeding from the arrangement and texture of parti-? 
" cles, is to be afcribed to their peculiar magnitude, fhape, combina, 
" tion, &c. fo that inftead of being an original property of matter, it 
" is, in fadt, only an occafional quality. Death is the privation of 
" fenfation, in confequence of the feparation of the fentient principle 
from the body: and this fentient principle, when a man dies, is de- 
" compounded into its fimple atoms, lofes its fenfitive powers, and goes 
<£ into other forms and combinations. The foul, in this refpeft, re- 
'c fembling the eye, which is no longer capable of performing its func- 
" tions than the connexion of its organized texture with the body lafts." 
What Asclepiades did, was to apply the principles of the Epi- 
curean Pnilofopby to medicine, and this he did with much ingenuity 
and acutenefs. Building upon that hypothefis, he fuppofed the hu- 
man body compofed of Epicurus' ultimate atoms, which, by their 
figure, proximity, and arrangement, enabled it to perform its functions ; 
and in a particular manner, that health confifted in the fymmetry and 
permeability of certain paffages through the firm parts, which he call- 
ed pores ; and the doling up, or obftrudion of thefe, conftituted dif- 
eafe. He imagined the fluids to be formed of particles, varying in 
figure and fize, and thus making all the varieties of them, from the 
thickeft blood to the moft attenuated animal fpirits. And when thefe 
fluids moved freely through their pores, the body was found ; but when 
they were too narrow, fo as to produce ftagnations, or fo oblique as not 
to he readily paffable, then indifpofition enfued. 
Such were the leading principles of Asclepiades, and he had ma- 
ny followers, among whom Themison of Laodicea was the moft: 
eminent. He rejected moft of the fubtle and laboured reafonings of 
his mafter, and, declaring fuch minute inveftigations were ufelefs, af- 
firmed, without defeending to particulars, and burthening himfelf with 
details, a phyfician need only make himfelf acquainted with the gen- 
eral principles of difeafes. Thefe, he faid, ail belonged to two claffes. 
I. Thofe proceeding from laxity ; and, 2. Such as were caufed by 
jlritture. All that was neceffary to be done, therefore, was to afeer- 
tain to which dais any given difeafe belonged ; and then, if to the 
former, to prefcribe aliringent; if to the latter, relaxing remedies. 
The regular and fyftematic plan which Themi$on and his numer- 
ous followers adopted in their practice, differing very widely from the 
conjectural and uncertain mode of other phyficians, caufed them to be 
called Methodists ; and they are to this day known in hiftory by 
the name of the Methodic Sect. While Themison was reflecting 
upon his fyftem, and endeavouring to advance it to maturity, he died, 
and the unfinifhed work was taken up and completed by h's follower 
Thessalvs. He lived in the time of Nero ; and having rejected, 
;ss frivolous, all the opinions of his predeceffors, he declaimed, with 
vehemence and fury, againft the phyficians of all ages, and offered to 
mltniit a beginner in the art of medicine in the fhort duration of fix 
months. And then, with a degree of arrogance afid impudence, of 
which, AMERICAN EDITION. 
XXI 
which, as no parallel is known to have exifted in ancient times, it can 
only be found in the hiftory of modern quackery, he took upon him- 
felf the appellation of or the conqueror of phyficians. 
After Thessalus the feft began to decline and dwindle, and al- 
though Soranus, Julian, and Moschion retarded for a while its 
downfall, yet it was totally abforbed and loft in the Galenic Doctrines 
which followed. 
Thus, from an examination of the Methodic Syjlem, it is evident the 
explanation of every thing in the animal economy is attempted upon 
principles of mechanism only. 
The firft notice of any thing elfe requifite to give life, and regulate 
its functions, feems to have occurred to Hippocrates, the cotempo- 
rary of Democritus and Leucippus. The to of this faga- 
cious obferver, as the interpretation of the word imports, obvioufly 
means an exciting power in animals : and the effefts of animation re- 
fulting from this, imperfectly known, and badly explained, doubtlefs 
give rife, according to the opinion and judgment of the different wri- 
ters, to the Nature of Sydenham,* the Aura Fitalis of Van Hel- 
M0NT,j- the Eis natura Medicatrix of Gaubius,^ the Anima Medica 
of Stahl and Nichols,$ and the learned and curious treatife, enti- 
tled Impetum Faciens, of Kaauw Boerhaave.|| 
And here it is worthy of remark, that from Hippocrates to 
Brown, all writers entertain the opinion of a principle or power with- 
in, exifting as the caufe of life, as appears by the active fignification of 
all their terms ; whereas the idea of the Brunonians is, that the or- 
ganized animal folid poffeffes no internal energy, and would always re- 
main inactive, unlefs excited by ftimuli from without; they therefore 
fpeak of the vital capacity in the pa/Jive voice, as only fufceptible ©f 
being aited upon. 
Herman Boerhaave, in his account of the difeafes of a lax and 
of a rigid fibre, feems again to relapfe into the mechanical confideration 
of thefe things ; but Haller, by his numerous and luminous experi- 
ments on fenfibility and irritability, led the way to a right mode of 
purfuing and underftandmg fuch enquiries. 
The attention of Hoffman had been turned to the confideration of 
the nervous fyftem, as influencing difeafes, more particular than any 
other perfon; and from his writings were probably taken the hints 
which terminated in Cullen's dodrine of Excitement and Collapfe, 
|n his Phyfiological Trad enlarged afterwards, and applied to prac- 
tice. 
* Opera PaHim. 
f Equidem fciant Spiritum effe aliquem illud impetum faciens Hippocrates, 
vitae clavum manu fua tenens (Ort. Medicin. p. 724.) 
| Who quotes Hippocrates for the idea (Sed. 649.) couched under the term 
«f autoxpxlaa. 
§ Animam effe Guhcrnatricem, &c. &c. Oratio de anima Mcdica. paflun. 
l| Lug. Batav. Luchtmans, 1745. (Chap. 2.) 
1 Inftitutes of Medicine, § 126 to 135. « From what has been now faid of 
the excitement and collapfe of the brain, it will appear that we fuppol'e life, as far 
as it is corporeal, to confift in the excitement of the nervous fyftem, and efpecially 
pf the brain, which unites the different parts, and forms them into a whole." 136. XXII 
INTRODUCTION TO THE 
tice, in his chapter on vefaniac, (Firft Lines, £ 1544- and feq.) as 
well as the obfervations in his letter on the recovery of perfons drown- 
ed : (p. 4.) " Though the circulation of the blood is neceftary to 
the fupport of life, the living ftate of animals does not confdt in that 
alone, but efpecially depends upon a certain condition of the nerves 
and mufcular fibres, by which they are fcnfible and irritable, and upon 
which the adtion of the heart itfelf depends/' &c. And alfo the re- 
marks on the effedt of ftimuli in keeping up the adtion and energy of 
the brain* at all times, in his treatife upon the materia medica. 
John Hunter had been fpeculating too on this fubjedi. In his 
experiments on animals, with refpedt to their power of producing 
heat, he has brought curious and important fadis to view : though 
his rcafoning on them is in fomeinftances inconclufive and exceptiona- 
ble, in others quite unphilofophical. This enquiry was intended as a 
counterpart to the experiments of Blagden, and his affociates in the 
heated chamber, on the power of the human body to produce cold in 
high temperatures. He afcribes a great deal, throughout his per- 
formance, to the ftimulant adtion of cold, and to the exhauftion of 
the whole of the powers of life in freezing animals, by their efforts to 
produce heat ; he even afcribes the attempt of his poor vidtim, the 
dormoufe, to get out of the veffel in which he was to be frozen to 
death, to the roofing of animal action by cold I He feems to take little 
notice of the vital organs, the fire-place whence the conftitution re- 
ceives its warmth ; nor regard much the condition of the refpiratory 
function in any of the creatures he operated upon, nor the pain they 
endured, and the changes in their economy confequent upon it. The 
experiments on the egg, frog, eel and fnail, may be as well explained 
on the idea of the increafed fufeeptibility of impreflion, produced by 
the fubdudfion of ftimuli, and by an extraordinary exertion of the 
refpiratory organs caufing a greater evolution of heat, as upon the 
author's hypothefis, which may be fummoned up in this general con- 
clufion; that cold produces its effedt in fufpending the voluntary ac- 
tions, by adting as a fedative to a certain point ; beyond which it 
feems to act as a Jllmulant, exciting the animal powers to exert them- 
felves for felf-prefervation. 
It will be evident to him who refiedis on what has been related, 
that the Epicurean Sectaries entertained no other than mechanical 
notions concerning the produdtion, adtions, and changes of bodies ; 
and that Hippocrates and his followers, though confiderably more 
advanced towards the truth, had gone no farther than to obferve foli- 
tary and individual facts, arrange thefe into detached fentences, or in- 
fulated aphorifms, fometimes intirely true, and fome containing only a 
mixture of truth ; or frame ftrange and whimfical hypothefes, by aid 
of which, as general principles, they attempted to explain things ; 
and the moft forward of them feems to have done little more than 
trace the corporeal fundtions, by partial indudtion, to the 
xaOaAlxco or COMMON SENSORY. 
Such was the condition of medical fcience, until almoft twenty-five 
years 
• Materia Medica, p. 67, &c. AMERICAN EDITION. 
XXIII 
Vtars ago, when, in that very place where Jpaftn, reaction, and vis med- 
ic at ri x natures were flourifiiing in full vigour, under the affiduous culti- 
vation of Cullen, they were nipped and cropped in the bloffom, and 
nearly eradicated as noxious, by the improving hand of Brown. 
From the intimate acquaintance which Brown, or Bruno, as he 
called hinifelf, had with the publifhed writings, and probably with the 
private opinions of Cullen ; from his academic habits, his erudition 
and knowledge of every thing palling at the Univerfity of Edinburgh, 
he muft have had great opportunities, as well of learning all that was 
printed in phyfic, as of Undying the defeats, and detecting the weak- 
nefs of that profelfor's do&rines. He told the writer of this preface, 
that he ventured one day to talk to Cullen on the incomprehenfible 
ideas of atony and fpafm exifting in the fame velfels of the body at 
the fame time ; and thereby provoked him to manifeft figns of impa- 
tience and difpleafure. A coolnefs took place immediately, which 
increafed at laft, by fucceflive and mutual aggravations, to rooted 
averfion and deep oppofition. And to this irritated Hate of Brown's 
mind, indignant with the fenfe of unbecoming treatment, is to be af- 
cribed no fmall portion of that refolution and energy with which he 
laboured out a Syftem of Medical Philofophy, which, though not free 
from errors, borrows, however, none from Cullen. 
On the publication and contents of the firft edition of the Elements 
Medicinae of this author I fhall be a little particular, on account of 
the fcarcity of the work, and of the gratification it may afford to an 
enquiring mind to learn the progrefs of ufeful difeoveries. 
It was publilhed in 1780, and was dedicated to Sir John Elliot; 
but this dedication was withheld from the fecond edition. After 
Hating his twenty years labour in learning and teaching phyfic, he 
obferves, it was not until the fourth luftrum that fome dawning of 
light broke in upon him. 
The opinion that in the phlegmafise of nofologifts, local affe&ioR 
was not the caufe of pyrexia, but, on the contrary, a fymptom confe- 
quent upon a previous general excitement of the whole conftitution, 
appears to have been early adopted by him ; and from his own perfon- 
al fufferings in eryfipelas, cynanche tonfillaris, catarrh, and fynocha, 
and from his perufal of whatever had been written by Morgagni, 
Triller, and other candid authors on thefe fubjefts, and on pneu- 
monia, he was confident his idea was right. 
* He, at this time, propofed the doftrine of cold predifpofing the 
body to be operated upon in a powerful manner, and to a morbid de- 
gree, by fubfequent heat; which, indeed, may be regarded as one of 
the moft important practical truths in medicine. 
He calls in queftion the propriety of forming opinions of the nature 
of difeafss by their fymptoms merely, and boldly adopts the method 
of judging from the " laedentia and juvantia." 
He offers well-founded criticifm on nofological arrangement, and 
(hews wherein, through want of diftin&ion between univerfal and local 
difeafes, a number of thefe had been claffed wrong. 
On examining the phlogiif.ic exanthemata he contends, that in 
meafle* XXIV 
INTRODUCTION TO THE 
mealies and fcariet fever, as well as in fmall-pox, the general indication 
of cure is to diminifh the inflammatory diathefis, without the leaft re- 
gard to the particular nature of thfc contagion, or the ftage of erup- 
tion ; but thefe are carefully to be diftinguilhed from the plague, and 
other eruptive difeafes of a totally oppofite charafter : and that with- 
out attending to the peculiarity of the refpiration, or the precife na- 
ture of the morbific caufe, the certain things to be attended to are. 
How far the difeafed condition deviates from health ; and in what de- 
gree the living body approximates towards death. Tlie exanthema- 
tous fymptoms in the two elaffes of complaints, varying in each, their 
form only, and not their nature. 
Having proceeded thus far, he declares that difeafes of the fame 
type or clafs are to be relieved, or cured, by the fame mode of treat- 
ment ; and that the volumes of diagnoses, and the endlefs diftinc- 
tions of nofology, in fpite of the authority of even Baglivi and Syd- 
enham, when oppofed to clear rcafon and matter of fact, ought to be 
difregarded. He expreffes his apprehenfions too, left the infinite dif- 
tin&ion of difeafes Ihould lead to a mode of practice equally diverli- 
fied, and have a very baneful effect upon materia mcdica and pre- 
fer! ptions. 
In his remarks upon predifpofition to bad health, be avers that no 
perfon ever fuddenly became fick, but that gradually a predifpofition 
was created by the agency of the exciting powers, and out of this pre- 
difpofition grew the difeafe. Of this he gives examples in the phlogif- 
tic exanthemata, wherein he fays, a high degree of excitement pro- 
duces the difeafe, a lower predifpofition, and a ftill lower health : the 
means, therefore, conducive to the latter of thefe he thinks fo fimple, 
that the ufe of the common nofology is intirely fuperfeded. 
Proceeding upon this plan, he diftinguiihes local from univerfal 
ailments ; both of which are confufedly claffed together, in the differ- 
ent nofological arrangements. 
This led him to an examination of hemorrhagy, which, if attended 
in the beginning with phlogiftic diathefis, he thought always became 
eventually afthenic, and in this enquiry it was that he was induced to 
call in queftion the exiftence of plethora, as a caufe of hemorrhagy, and 
to rejeft altogether the notion of a vis medicatrix naturae as an agent 
in the animal fyftem. 
This firft edition of the Elementa is an unfiniflied work, and com-, 
prebends the details of his dodrine no farther than the fhenic form of 
difeafes. Among thefe he there ranks hemorrhagy, efpecially menor- 
rhagia, hiemorrhois, epiftaxis, and apoplexy ; an arrangement which 
he afterward confidered wrong, and altered accordingly in the fol- 
lowing editions, by placing them all in the afthenic clafs. 
Such, he tells us, was the train of i4eas palling in his mind as he 
reflected upon the animal economy ; and Upon thefe confiderations 
did he judge himfelf warranted in undertaking an explanation of the 
fubject, different in many refpe&s from any thing done before him. 
He declares, throughout the whole, he never defeends beneath his 
dignity to animadvert upon particular perfons ; though in certain 
cafes, AMERICAN EDITION. 
XXV 
dafes, where almoft implicit faith and idolatrous reverence had been 
given to certain authors, he has freely attacked and refuted their 
opinions. He apologizes for the plainnefs of ftile and manner with 
which the performance is written, efpecially, fince to avoid the conta- 
gion of opinion, he had read no medical book for five whole years, 
and had fcarcely confulted the monuments of ancient elegance for 
twenty. 
There is a great deal of animation and force in his argument againft 
plethora, from the ninety-fourth to the ninety-eighth feCtion, which 
he concludes with this challenge : " Si fit quod ad hoc refpondeas, 
" refponde Stahli aut jube Junckerum."* 
In the hundred and fourth feCtion he oppofes, in decided terms, the 
tonic or aftringent operation of cold, particularly as caufing conftriCtiori 
of the ficin ; and repeats the fame in feveral places, 180-182.) de- 
nying that it aCts as a ftimulant. 
In his reafoning againft lentor in the fluids as a caufe of difeafe, he 
breaks out into the following fpirited exclamation : " Quam infelix 
" ea pathologia eft ! cujus perpetuum principium, quod univerfis 
" comprehenfis partibus convenire, univerfas illuftrare, et explicate 
" debet, ne uni quidem convenit, unam illuftrat, unam explicat, con- 
" tra omnibus repugnat, omnes obfeurat, et confundit and, reject- 
ing the pathology of the fluids, declares, that cool water, pure air, 
wine, and Peruvian bark refill putrefaction in no other way than by 
keeping up excitement. 
In his remarks upon fpafm, he endeavours to fhew that it cannot be 
a caufe of difeafe, either of the fthenic or afthenic kind, and ought, of 
courfe, to be rejected from both, as ftiould alfo what has been called 
the reaction of the fyjlem, in fever. In the courfe of his animated ar- 
gument, he alks if, toward the end of the eighteenth century, " quis, 
" opinionem meram, nulla rationis, nulla veri vel tenuiflima umbra com- 
" mendatam, folidiflimis argumentis, item ipfi tuendse adhibitis com- 
" pertam falfam, poll vanam omni falfse logicae genere defenfionem, 
" pro re vera et certa oblatum iri crederet ?" 
He is every where oppofed to that claffification and arrangement of 
difeafes which has fo much obtained of late, and clofes this work with 
the words, " Nofologia delenda." 
He publiihed a fecond edition in the year 1784, and added thereto 
the afthenic clafs of difeafes. Taught by experience and obfer- 
vation, in the different forms of the gout and afthma, of the benefit 
of ftimulant remedies, he had no hefitation to coniider them among the 
effeCts of weaknefs ; as were like wife fevers ftriftly fo called (febres) 
both intermittent and continued, and all the kinds of hemorrhagy, &c. 
In fhort, the confideration of the difeafes not belonging to the fthen- 
ic clafs, convinced him they muft be referred to the afthenic ; fuch 
were all fpafmodic or convulfive ailments, dyfpepfia, and other the like 
affeCtions of the alimentary canal, and the greater part of the maladies 
of children. 
Vol. I. d lu 
* Note. Juncker was the difciplc of Stahl and the expofiter of his doArines XXVI 
INTRODUCTION TO THE 
In this performance too, he contends againft the advocates for fed- 
atives. Opium, he declares, has a ftimulant operation ; colds or ca- 
tarrhs are produced by heat fucceeding to cold, and not vice verfa ; 
and extends his laws of animation to the vegetable creation. 
In ftiort, he concluded there was in the medullary nervous matter, 
and mufcular folid of living bodies, which have been generally called 
the nervous fyftem, a property by which they could be affedfed by 
outward agents, as well as by their own functions, in fuch a way as~to 
produce the phenomena peculiar to the living ftate. This capacity of 
being acted upon is termed excitability, and the agents are all denom- 
inated Jlimulants, while the effedt produced by the operation of ftimu- 
lants upon excitability is called excitement. 
Excitement is terminated in two ways. I. By the exhauftion of 
excitability, through the violence or continuance of ftimulus, which 
is called indirect debility. 2. By the accumulation of excitability, 
through deficient ftimulus, which is termed direct debility. Between 
the two extremes of indirect and diredt debility are experienced both 
health and difeafes of the fthenic kind, or thofe febrile complaints (py- 
rexise,) accompan'ed with what has been called phlogiftic diathefis, 
wherein, though the excitement confiderably exceeds the healthy rate, 
Rill it does not reach the limits of indiredl debility. 
Stimuli lofe their efficacy after long and frequent application ; but 
even then the excitability, exhaufted in relation to one ftimulus, is ca- 
pable of being added upon by another. 
Therefore, the walk of excitability, after exhauftion of one ftimu- 
lus after another, is very hard to be repaired, by reafon of the difficul- 
ty of accefs to freffi ftimuli to work upon the languiffiing excitability ; 
which, by being applied ftrong at firft, and gradually weakened after- 
wards, anfwers the purpofe ; and alfo the fuperabundant excitabili- 
ty left by fubdudfion of one ftimulus after another, produces fuch an 
excitable condition of the fyftem, that much nicety is requifite to wear 
it gradually awav by application of very weak ftimuli at firft, and by 
degrees ftronger and ftronger, until the accuftomed ones can be com- 
fortably, borne. According to the Brunonian Dodirine difeafes ap- 
pear under various modifications, as exhibited in the table below. 
Thus they may be, 
I. Univerfal, fuch as primarily affedt the whole conftitution, as fe- 
vers, &c. 
2. Local, where, from limited morbid affedtion, a particular part 
labours, without difordering the intire habit; as trifling wounds, 
phlegmons, &c. 
3. Loco-univerfal, when, from a local affection, the whole body is 
eventually brought into a difeafed condition ; as in lues originat- 
ing from chancre, fmall-pox from inoculation, &c. 
4. Uriiverfo-local ; as if after a general ailment any particular part 
or organ is affected in a fecondary way ; as the eruptions of exan- 
thematous pyrexiae, fvphilitic blotches, &c. 
And each ot thefe forms of difeafes muff confift either in, 
1. 1 >iicdt debility ; as in feurvy, hunger, cold, &c. 
2. Sthenic AMERICAN EDITION. 
XXVII 
2. Sthenic diathefis ; as in pleurify, other forms of fynocha, &c. 
3. Indireft debility ; as in old age, intoxication, fatigue, &c. 
4. Direft debility added to indireft ; as in gout very often, and in 
many difeafes of advanced life. 
5. Indireft debility added to direft ; as in over-feeding a familhed 
perfon, &c. in mod difeafes of infants and young perlons. 
Let now the candid reader compare this view with the opinions of 
the old Methodists, and fay, whether it be a mere revival of the 
praftice of Themison and Thessalus ? Surely they who have af- 
ferted it was, can never be fuppofed to have given theinfelves the trou- 
ble to examine. ' j 
Yet, with all this novelty about it, Brown's doftrine wants pre- 
cifion. It proceeds not far enough beyond general principles, which, by 
reafon of their abftraft or fpeculative nature, have not been found elofely 
enough applicable to the fubjefts of pathologyand phyfiology. He takes 
for granted, for inftance, that the nervous fyftem is always one and 
the fame excitable thing. He fays fcarcely any thing accurate on the 
different qualities of the blood and circulating fluids, and of the fecre- 
tions ; and gives nothing very minute concerning the mighty influence 
of the refpiratory and digeftive proceffes upon the animal ceconomy. 
He pafles over entirely the chemical compolition of our food and 
drink, of our inhalations and excretions, of the gafes we breathe and 
the remedies we fwallow ; in Ihort, he has left not a fentence on the 
compofition or the nature of bone, mufcle, veffel, fat, lymph, or 
gluten, nor how varioully thefe are affefted by difeafe, nor in what 
their healthy differs from their morbid Hate, nor by what means the 
alterations they undergo are brought about. 
Thefe, and other omilfions and defefts in the Brunonian System, 
called for amendment; and this was to be begun by attending to the 
varying condition of the living folid, and the concomitant ftate of the 
fluids. 
The eftablilhment of the new nomenclature of chemidry in France, 
in 1787, may be confidered as forming a new epoch in fcience. Since 
the publication of that invaluable performance, language has been 
adapted with greater accuracy to the expreflion of ideas, and philo- 
lophical inveiligation conducted with fuperior advantage and fuccefs. 
Lavoisier, in his Elements of Chemiftry, has attempted the expla- 
nation of the putrefaftive, as well as the fermentative procefs in the 
organized forms of animals and of plants, upon the modern principles ; 
and, in a natural and convincing manner, has proceeded a great way 
beyond any one who undertook the explanation before, Spallan- 
zani indeed, in his Experiments on the Concoftion of Food in 
the Stomach, and Crawford, in his Application of the Principles of 
Combuftion to the Funftion of the Lungs in breathing, had given ex- 
cellent fpecimens of this mode of reafoning on phyfiological fubjefts. 
Great progrefs has been made fince in detefting the nature and prop- 
erties of the atmofphere, the gafes and aeriform fluids ; and the right 
knowledge of thefe, derived from experiment and obfervation, has fur- 
nilhed XXVIII 
INTRODUCTION TO THE 
nifhed the means of expounding many of the animal funftions, in a 
plain and happy manner. 
We do not merely know, at prefent, that there is a gafeous produc- 
tion, pure air., neceflary to the prefervation and continuance of animal 
life ; but we think we know it is a compound fubftance, and what its 
compound ingredients are ; we believe we can make and unmake it ar- 
tificially, and that nature is doing fo inceflantly : we think the term 
" dephlogifticated air" not accurately nor logically applied; but, 
judging from its tendency to produce fournefs when combined with 
other bodies, wc call the bails of it " the acidifying principle," and 
the combination of that bafe with light and caloric or the matter of 
heat, " oxygene gas or air," or more properly " gafeous oxyd of light." 
From noting the operation of this oxygene, or principle of fouring, 
Upon various bodies, we imagine we know the compofition of acids, and 
have made out a confiderable lift of acidifiable bafes; fo that the forma- 
tion of fixed air from oxygene and carbone, or charcoal, of nitrous acid 
from it and azote, of vitriolic acid from the fame and fulphur, and phof- 
phoric acid from its union with phofphorus, feem to be well eftablifti- 
ed truths. We imagine that a certain other clafs of bodies capable of 
combining with oxygene, but not to the point of acidity, forms there- 
by half-acids or oxyds, and that thus the calces of metals, animal 
blood and fecretions, as well as the farinaceous, gummy, and mucil- 
aginous parts of plants, are formed. 
We think the compofition of water is underftood, andinftead of be- 
ing an elementary body, as was formerly believed, that it is, in fadt, 
but the oxyde of hydrogen, or a combination of this latter fubftance 
with the principle of acidity, but not to the fouring point. 
It is confidered alfo, that more is known concerning the compofition 
of the irritable fibre, of the adipofe matter, and of the bones : and that 
the effects produced upon the circulated fluids by breathing, and 
through them upon the folids of the animal body in health, and the 
alterations too that the liquid and firm parts undergo by impeding, 
vitiating, or obftrudting that fundtion, in ordinary cafes, as well as 
in gravid females, are now better comprehended than they ufed to be. 
Inafmuch, that after the great light thrown upon this fubjedt, fucceed- 
ing authors have been enabled to drefs up the Brunonian Syftem in 
the more recent fafhion, and, to fupply and adorn it with almoft all 
that was wanting to make it additionally engaging and attrac- 
tive. Drowning, fuffocation, fcurvy, ftone, dyfentery, peftilencc, ulcers 
and fever, have already received great elucidation, both in theory and 
pradiice, from the application of chemical principles ; and we may 
reafonably hope, that before many more years elapfe, better and more 
corredl ideas will be entertained of many articles of the materia medica, 
and of their manner of operating ; that a new medical nomenclature 
(than which nothing in fcience is more wanting) will be made out ; 
and that, from the afcertained condition of the body, and the known 
compofition and operation of remedies, phyficians may prefcribe fairly 
for the adlual ftate of the conftitution, and the removal of the prefent 
malady, AMERICAN EDITION. 
XXIX 
malady, without being milled, as too often happens at prefent, by fpe- 
cious words, and idle or deceitful names. 
But, notwithftanding the many and beautiful applications of chem- 
ical principles to the explanation of the animal functions, we are not to 
imagine every thing in life fufceptible of chemical interpretation. 
What it is that enables the atoms compofing a mufcle to cohere, and 
the mufcle to contract and perform great exertions of ftrength, we 
know not ; but this we know very well, that we can never form a muf- 
cle by fynthefis, or the putting together, in any artificial form, thofe 
fubftances which appear, from analyfis, to conftitute a mufcle. There 
is fomething in animated exiftence, which eludes our moft active re- 
fearches, and which defies fubmiffion to either mechanical or chemical 
l?ws. With refpeft to chemical modes of reafoning upon thefe fub- 
jeds, it is obfervable, that they apply, with their greateft extent and 
accuracy, to fuch parts of the body as have the loweft degrees of ani- 
mation, as the contents of the inteftines, the teeth, bones, fat, fubftan- 
ces adhering to the Ikin, and, generally fpeaking, the circulated and 
fecreted fluids ; while the qualities of mufcular fibres, by which they 
b ecome contractile, and of nervous expfinfions, whereby they take on 
fenfation, with the whole of the functions arifing from irritability and 
fenfibility, are referable to other and different laws. 
The inveftigation of thefe Laws of Organic Life is attempted by 
our learned and very ingenious author in the following work. The 
Zoonomia, therefore, though not exempt from fanciful and vifionary 
doctrines, prefents confiderations of the firft importance, both to the 
fpeculative philofopher and the practical phyfician ; to him who con- 
templates the operations of mind as a fcience, or to him that attends 
to the corporeal functions as an artlft. The fecond part of this work 
being engaged in an arrangement of difeafes, with their remedies and 
modes of treatment, will be very acceptable to the practical as well as 
the theoretical phyfician. After the different projects for methodiz- 
ing this department of knowledge, which have fucceffively been offer- 
ed to the public with fo little advancement of true fcience, the friends 
of medical improvement and of the healing art will joyfully accept 
of fomething that promifes to lead them from arbitrary fyftem to nat- 
ural method. And as the diftinftions are founded upon the increafed^ 
decreafedor inverted aCtions of the moving machinery of the body, it 
will inftantly be perceived how clolely the Brunonian doftrine is inter- 
woven with the whole fubjeft. It is however to be always borne in 
mind that on American difeafes the phyficians of this country have 
generally written the beft. 
SAMUEL L. MITCH ILL. 
New York, Nov. 3, 1802. Z O O N O M I a; 
OR, 
THE LAWS OF ORGANIC LIFE* 
. PART I. 
CONTAINING 
THE IMMEDIATE CAUSES OF ANIMAL MOTIONS, 
DEDUCED FROM 
THEIR MORE SIMPLE OR FREQUENT APPEARANCES IN HEALTH, 
AND APPLIED TO EXPLAIN 
THEIR MORE INTRICATE OR UNCOMMON OCCURRENCES IN 
DISEASES. 
FELIX, <^UI POTUIT RERUM COGNOSCERE CAUSAS. Z O O N O M I A. 
SECT. I. 
OF MOTION. 
THE whole of nature may be fuppofed to confift of two 
eflences or fubftances ; one of which may be termed, 
fpirit, and the other matter. The former of thefe poflefles the 
power to commence or produce motion, and the latter to receive 
and communicate it. So that motion, confidered as a caufe, im- 
mediately precedes every e fie (ft ; and confidered as an effect, it 
immediately fucceeds every caufe. And the laws of motion 
therefore are the laws of nature. 
The motions of matter may be divided into two kinds, 
primary and fecondary. The fecondary motions are thofe, which 
are given to or received from other matter in motion. Their 
lawshave been fuccefsfully inveftigated by philofophers in their 
treatifes on mechanic powers. Thefe motions are diftinguilhed 
by this circumftance, that the velocity multiplied into the quan- 
tity of matter of the body afted upon is equal to the velocity 
multiplied into the quantity of matter of the adding body. 
The primary motions of matter may be divided into three 
clafles, thofe belonging to gravitation, to chemiftry, and to life ; 
and each clafs has its peculiar laws. Though thefe three clafles 
include the motions of folid, liquid, and aerial bodies ; there is 
neverthelefs a fourth divifion of motions; I mean thofe of the 
fuppofed ethereal fluids of magnetifm, eleddricity, heat, and 
light; whofe properties are not fo well inveftigated as to be 
clafled with fufficient accuracy. 
xjl. The gravitating motions include the annual and diurnal 
rotation of the earth and planets, the flux and reflux of the 
ocean, the defeent of heavy bodies, and other phenomena of 
gravitation. The unparalleled fagacity of the great Newton 
has deduced the laws of this clafs of motions from the fiinple 
principle of the general attraction of matter : to which fhould 
perhaps be added the general repulfion of matter ; which feems 
Vol. I. B to 2 
OF MOTION. 
Sect. I. 
to have caufed the projection of the planets from the fun, and 
to prevent their relapfe into one chaotic mafs. Thefe motions 
are distinguished by their tendency to or from the centres of the 
fun or planets. 
id. The chemical clafs of motions includes all the various ap- 
pearances of chemiRry. Many of the faCts, which belong to 
thefe branches of fcience, are nicely afcertained, and elegantly 
claSTed ; but their laws have not yet been developed from fuch 
fimple principles as thofe above mentioned ; though it is prob- 
able, that they depend on the fpecific attractions belonging to 
the particles of bodies, or to the difference of the quantity of at- 
traction belonging to the Sides and angles of thofe particles, to 
which fhould perhaps be added the fpecific repulfions belonging 
to the particles of bodies. When thefe repulfions prevail over 
the attractions, they may caufe the diffusions of light and of 
odours, the explofions of fome bodies, and the flower decompo- 
fition of others, and occafion our ideas of fluidity; when the 
attractions prevail over the repulfions, they may caufe the Strict- 
er combinations and cohefions of matter, as in cryftalization or 
cooling, and give rife to our ideas of folidity ; and when thefe 
two caufes of motion are in aCtive equilibrium, they may pro- 
duce the vibrations of the particles of bodies, and occafion our 
ideas of found. The chemical motions are distinguished by their 
being generally attended with an evident decompofition or new 
combination of the aCtive materials. 
3 J. The third clafs includes all the motions of the animal and 
vegetable world ; as well thofe of the veSfels, which circulate 
their juices, and of the mufcles, which perform their locomotion, 
as thofe of the organs of fenfe, which constitute their ideas. 
This lalt clafs of motion is the fubjeCt of the following pages ; 
which, though confcious of their many imperfections, I hope 
may give fome pleafure to the patient reader, and contribute 
fomething to the knowledge and to the cure of difeafes. 
SECT. Sect. II. i. i. 
DEFINITIONS. 
3 
SECT. II. 1. 
EXPLANATIONS AND DEFINITIONS. 
I. Outline of the animal economy.---IL I. Of the fenforium. 2. 
Of the brain and nervous medulla. 3. A nerve. 4. A mufcu- 
lar fibre. 5. The immediate organs of fenfe. 6. The external 
organs of fenfe. 7. An idea or fenfual motion. 8. Perception, 
g. Senfation. 10. RecolleBion and fuggefiion. 11. Habit, caufa- 
tion, afociation, catenation. 12. Ref ex ideas. 13* Stimulus defined- 
As fome explanations and definitions will be neceflary in the profecu- 
tion of the work, the reader is troubled with them in this place, and 
is intreated to keep them in his mind as he proceeds, and to take 
them for granted, till an apt opportunity occurs to evince theirtruth; 
to which 1 fhall premife a very fhort outline of the animal economy. 
I.-i. The nervous fyftem has its origin from the brain, and 
is diftributed to every part of the body. Thofe nerves, which 
ferve the fenfes, principally arife from that part of the brain, 
which is lodged in the head ; and thofe, which ferve the pur- 
pofes of mufcular motion, principally arife from that part of the 
brain, which is lodged in the neck and back, and which is erro- 
neoufly called the fpinal marrow. The ultimate fibrils of thefe 
nerves terminate in the immediate organs of fenfe and mufcular 
fibres, and if a ligature be put on any part of their paflage from 
the head oi' fpine, all motion and perception ceafe in the parts 
beneath the ligature. 
2. The longitudinal mufcular fibres compofe the locomotive 
mufcles, whofe contraCtions move the bones of the limbs and 
trunk, to which their extremities are attached. The annular or 
fpiral mufcular fibres compofe the vafcular mufcles, which con- 
ftitute the inteftinal canal, the arteries, veins, glands, and ab- 
forbent veflels. 
3. The immediate organs of fenfe, as the retina of the eye, 
probably confift of moving fibrils, with a power of contraCtion 
fimilar to that of the larger mufcles above defcribed. 
4. The cellular membrane confifts of cells, which refemble 
thofe of a fponge, communicating with each other, and con- 
necting together all the other parts of the body. 
5. The arterial fyftem confifts of the aorta and the pulmona- 
ry artery, which are attended through their whole courfe with 
their 4 
DEFINITIONS. 
Sect. II. 1. 6. 
their correfpondent veins. The pulmonary artery receives the 
blood from the right chamber of the heart, and carries it to the 
minute extenfive ramifications of the lungs, where it is expofed 
to the action of the air on a furface equal to that of the whole 
external Ikin, through the thin moift coats of thofe veflels, which 
are fpread on the air-cells, which conftitute the minute terminal 
ramifications of the wind-pipe. Here the blood changes its 
colour from a dark red to a bright fcarlet. It is then colle&ed 
by the branches of the pulmonary vein, and conveyed to the 
left chamber of the heart. 
6. The aorta is another large artery, which receives the blood 
from the left chamber of the heart, after it has been thus aera- 
ted in the lungs, and conveys it by afcending and defcending 
branches to every part of the fyftem ; the extremities of this ar- 
tery terminate either in glands, as the falivary glands, lachrymal 
glands, &c. or in capillary veflels, which are probably lefs invo- 
luted gland's; in thefe fome fluid, as laliva, tears, perfpiration, is 
feparated from the blood ; and the remainder of the blood is 
abforbed or drank up by branches of veins correfpondent to the 
branches of the artery; which are furnifhed with valves to prevent 
its return; and is thus carried back, after having again changed 
its colour to a dark red, to the right chamber of the heart. The 
circulation of the blood in the liver differs from this general fyf- 
tem ; for the veins which drink up the refluent blood from thofe 
arteries, which fpread on the bowels and mefentery, unite into 
a-trunk in the liver, and form a kind of artery, which is branch- 
ed into the whole fubftance of the liver, and is called the vena 
portarum; and from which the bile is feparated by the numer- 
ous hepatic glands, which conftitute that vifeus. 
7. The glands may be divided into three fyftems, the convo- 
luted glands, fuch as thofe above defcribed, which feparate bile, 
tears, faliva, &c. Secondly, the glands without convolution, as 
the capillary veflels, which unite the terminations of the arteries 
and veins; and feparate both the mucus, which lubricates the cel- 
lular membrane, and the perfpirable matter, which preferves the 
fkin moift and flexible. And thirdly, the whole abforbent fyftem, 
confifting of the la&eals, which open their mouths into the ftom- 
ach and inteftines. and ofthe lymphatics, which open their mouths 
on the external furface of the body, andon the internal linings of all 
the cells of the cellular membrane, and other cavities of the body. 
Thefe ladleal and lymphatic veflels are furniflied with nu- 
merous valves to prevent the return of the fluids, which they 
abforb, and terminate in glands, called lymphatic glands, and 
may hence be confidered as long necks or mouths belonging to 
thefe glands. To thefe they convey the chyle and mucus, with 
a Sect. II- 1. 8. 
DEFINITIONS. 
5 
a part of the perfpirable matter, and atmofpheric moifture ; all 
which, after having paded through thefe glands, and having 
fuffered fome change in them, are carried forward into the 
blood, and fupply perpetual nourilhment to the fyftem, or re- 
place its hourly wafte. 
8. The ftomach and inteftinal canal have a conftant vermic- 
ular motion, which carries forwards their contents, after the 
lacteals have drank up the chyle from them; and which is ex- 
cited into a&ion by the ftimulus of the aliment we fwallow, but 
which becomes occafionally inverted or retrograde, as in vomit- 
ing, and in the iliac paflion. 
II. i. The word fenforium in the following pages is defign- 
ed to exprefs not only the medullary part of the brain, fpinal 
marrow, nerves, organs of fenfe, and of the muicles; but a:fo 
at the fame time that living principle, or fpirit of animation, 
which relides throughout the body, without being cognizable to 
our fenfes, except by its cflcQs. The changes which occafion- 
ally take place in the fenforium, as during the exertions of voli- 
tion, or the fenfations of pleafure or pain, arc termed fenforial 
motions. • 
2. The fimilarity of the texture of the brain to that of the 
pancreas, and fome other glands of the body, has induced the 
inquirers into this fubjedt to believe, that a fluid, perhaps much 
more fubtile than the eleilric aura, is feparated from the blood 
by that organ for the purpofes of motion and fenfation. When 
we recollect, that the electric fluid itfelf is actually accumulated 
and given out voluntarily by the torpedo and the gymnotus elec- 
tricus, that an electric (hock will frequently ftimulatc into mo- 
tion a paralytic limb, and laftly that it needs no perceptible tubes 
to convey it, this opinion feems not without probability'; and 
the Angular figure of the brain and nervous fyftem feems well 
adapted to diftribute it over every part of the body. 
For the medullary fubftance of the brain not only occupies 
the cavities of the head and fpine, but palles along the innumer- 
able ramifications of the nerves to the various mufcles and or- 
gans of fenfe. In thefe it lays afide its coverings, and is inter- 
mixed with the ilender fibres, which conftitute thofe mufcles 
and organs of fenfe. Thus all thefe diftant ramifications of the 
fenforium are united at one of their extremities, that is, in the 
head and fpine ; and thus thefe central parts of the fenforium 
conftitute a communication between all the organs of fenfe and 
mufcles. 
3. A nerve is a continuation of the medullary' fubftance of 
the brain from the head or fpine towards the other parts of the 
body, wrapped in its proper membrane. 
4. The 6 
DEFINITIONS. 
Sect. II. 2. 4. 
4- The mufcular fibres are moving organs intermixed with that 
medullary fubftance, which is continued along the nerves, as 
mentioned above. They are indued with the power of contrac- 
tion, and are again elongated either by antagonift mufcles, by 
circulating fluids, or by elaftic ligaments. So the mufcles on 
one fide of the fore-arm bend the fingers by means of their ten- 
dons, and thofe on the other fide of the fore-arm extend them 
again. The arteries are diftended by the circulating blood; 
and in the necks of quadrupeds there is a ftrong elaftic liga- 
ment, which aflifts the mufcles, which elevate the head, to keep 
it in its horizontal pofition, and to raife it after it has been de- 
prefled. 
5. The immediate organs of fenfe confift in like manner of 
moving fibres enveloped in the medullary fubftance above men- 
tioned ; and are erroneously fuppofed to be fimply an expanfion 
of the nervous medulla, as the retina of the eye, and the rete 
mucofum of the fkin, which are the immediate organs of vifion, 
and of touch. Hence when we fpeak of the contractions of the 
fibrous parts of the body, we (hall mean both the contractions 
of the mufcles, and thofe of the immediate organs of fenfe. 
Thefe fibrous motions are thus diftinguilhed from the fenforial 
motions above mentioned. 
6. The external organs of fenfe are the coverings of the im- 
mediate organs of fenfe, and are mechanically adapted for the 
reception or tranfmiflion of peculiar bodies, or of their qualities, 
as the cornea and humours of the eye, the tympanum of the ear, 
the cuticle of the fingers and tongue. 
7. The word idea has various meanings in the writers of 
metaphyfic: it is here ufed fimply for thofe notions of external 
things, which our organs of fenfe bring us acquainted with orig- 
inally j and is defined a contraCtion, or motion, or configuration, 
of the fibres, which conftitute the immediate organ of fenfe ; 
which will be explained at large in another part of the work. 
Synonymous with the word idea, we Ihall fometimes ufe the 
words fenfual motion in contradiftinCtion to mufcular motion. 
8. The word perception includes both the aCtion of the organ 
of fenfe in confequence of the impaCt of external objcCis, and 
our attention to that action ; that is, it exprefles both the motion 
of the organ of fenfe, or idea, and the pain or pleafure that fuc- 
ceedsor accompanies it. 
9. The pleafure or pain which neceflarily accompanies all 
thofe perceptions or ideas which we attend to, either gradually 
fubfides, or is fucceeded by other fibrous motions. In the latter 
cafe it is termed fenfation^ as explained in SeCl. V. 2, and VI. 
2.-The reader is intreated to keep this in his mind, that 
through Sect. II. 2. 10. 
DEFINITIONS. 
7 
through all this treatife the word fenfation is ufed to exprefs 
pleafure or pain only in its aCtive ftate, by whatever means it is 
introduced into the fyftem, without any reference to the ftimu- 
lation of external objects. 
io. The vulgar ufe of the word memory is too unlimited for 
our purpofe : thole ideas which we voluntarily recall are here 
termed ideas of recolleEiiony as when we will to repeat the alpha- 
bet backwards. And thofe ideas which are fuggefted to us by 
preceding ideas are here termed ideas of fuggejliony as whilft we 
repeat the alphabet in the ufual order; when by habits previ- 
oully acquired B is fuggefted by A, and C by B, without any 
effort of deliberation. 
ii. The word ajjbciation properly lignifies a fociety or con- 
vention of things in fome refpeCts fimilar to each other. We 
never fay in common language, that the effect is affociated with 
the caufe, though they neceffarily accompany or fucceed each 
other. Thus the cuniraCliuns of our mufdes and organs of 
fenfe may be faid to be affociated together, but cannot with pro- 
priety be faid to be affociated with irritations, or with volition, 
or with fenfation ; becaufe they are caufed by them, as men- 
tioned in SeCt. IV. When fibrous contractions fucceed other 
fibrous contractions, the connexion is termed ajjbciation ; when 
fibrous contractions fucceed fenforial motions, the connexion 
is termed caujation ; when fibrous and fenforial motives recipro- 
cally introduce each other in progreffive trains or tribes, it is 
termed catenation of animal motions. All thefe connexions are 
faid to be produced by habit: that is, by frequent repetition. 
12. It may be proper to obferve, that by the unavoidable idi- 
om of our language the ideas of perception, of recollection, or of 
imagination, in the plural number fignify the ideas belonging to 
perception, to recolleCtion, or to imagination ; whilft the idea 
of perception, of recolleCtion, or of imagination, in the fingular 
number is ufed for what is termed " a reflex idea of any of thofe 
operations of the fenforium." 
13. By the word Jlimulus is not only meant the application of 
external bodies to our organs of fenfe and mufcular fibres, which 
excites into aCtion the fenforial power termed irritation ; but al- 
fo pleafure or pain, when they excite into aCtion the fenforial 
power termed fenfation ; and defire or averfion, when they ex- 
cite into aCtion the power of volition; and laftly, the fibrous 
contraCtions which precede aflbeiation; as is further explained 
in SeCt. XII. 2. 1. 
SECT. 8 
MOTIONS OF 
Sect. III. 1. 1. 
S E C T. III. 
THE MOTIONS OF THE RETINA DEMONSTRATED BY EXPERI- 
MENTS. 
I. Of animal motions and of ideas. II. The fibrous flrufiure of the 
retina. III. The activity of the retina in vifion. I. Rays of 
light have no momentum. 2. Objects long viewed become fainter. 
3. Spectra of black objects become luminous. 4. Varying fpeclra 
from gyration. 5. From long infpedlion of various colours. IV. 
Motions of the organs of fenfe conftitute ideas, I. Light from 
prefftng the eye-ball, and foundfrom the pit fation of the carotid ar- 
tery. 2. Ideas in feep mifaken for perceptions. 3. Ideas of im- 
agination produce pain andficknefs like fenfations. 4. When the 
organ offenfe is def rayed, the ideas belonging to that fenfe perifj. 
V. Analogy between mufcular motions and fenfual motions, or 
ideas. I. I hey are both originally excited by irritations. 2. And 
officiated together in the fame manner. 3. Both ahi in nearly the 
fame times. 4. Are alike frengthened or fatigued by exercife. 
5. Are alike painful from inflammation. 6. Are alike benumb- 
ed by compreffion. 7. Are alike liable to paralyfis. 8. To con- 
vulfon. 9. To the influence of old age.-VI. Objections anfwered. 
1. Why we cannot invent new ideas. 2. If ideas refemble exter- 
nal objects. 3. Of the imagined fen fation in an amputated limb. 
4. Abflracl ideas.-VII. What are ideas, if they are not ani- 
ir.al motions ? 
Before the great variety of animal motions can be duly ar- 
ranged into natural clafies and orders, it is neceffary to fmooth 
the way to this yet unconquered field of fcience, by removing 
feme obftacles which thwart our paflage. I. To demonftrate 
that the retina and other immediate organs of fenfe pofiefs a 
power of motion, and that thefe motions conftitute our ideas, 
according to the fifth and feventh of the preceding affertions, 
claims our firft attention. 
Animal motions are diftinguifhed from the communicated 
motions, mentioned in the firfl: fciStion, as they have no me- 
chanical proportion to their caufe ; for the goad of a fpur on the 
Ikin of a horfe fnall induce him to move a lead of hay. They 
differ from the gravitating motions there mentioned as they are 
exerted with equal facility in all directions, and they differ from 
the chemical clafs of motions, becaufe no apparent decompofi- 
ticns or new combinations are produced in the moving ma- 
terials. 
Hence, Sect. III. 1. 1. 
THE RETINA. 
9 
Hence, when we fay animal motion is excited by irritation, we 
do not mean that the motion bears any proportion to the me- 
chanical impulfe of the ftimulus ; nor that it is affeCled by the 
general gravitation of the two bodies ; nor by their chemical 
properties ; but folely that certain animal fibres are excited in- 
to action by fomething external to the moving organ* 
In this fenfe the ftimulus of the blood produces the Contrac- 
tions of the heart •, and the fubftances we take into our ftomach 
and bowels ftimulate them to perform their neceflary functions. 
The rays of light excite the retina into animal motion by their 
ftimulus ; at the fame time that thofe rays of light themfelves 
are phyfically converged to a focus by the inaCtive humours of 
the eye. The vibrations of the air ftimulate the auditory nerve 
into animal action ; while it is probable that the tympanum of 
the ear at the fame time undergoes a mechanical vibration. 
To render this circumftance more eafy to be comprehended, 
motion may be defined to be a variation of figure ; for the whole 
univerfe may be confidered as one thing poflefling a certain fig- 
ure ; the motions of any of its parts are a variation of this fig- 
ure of the whole : this definition of motion will be further ex- 
plained in Section XIV. 2. 2. on the production of ideas. 
Now the motions of an organ of fenfe are a fuccefiion of con- 
figurations of that organ ; thefe configurations fucceed each 
other quicker or flower ; and whatever configuration of this or- 
gan of fenfe, that is, whatever portion of the motion of it is, or 
has ufually been, attended to, conftitutes an idea. Hence the 
configuration is not to be confidered as an effeCt of the motion 
of the organ, but rather as a part or temporary termination of it; 
and that, whether a paufe fucceeds it, or a new configuration 
immediately takes place. Thus when a fuccefiion of moving 
objects are prefented to our view, the ideas of trumpets, horns, 
lords and ladies, trains and canopies, are configurations, that is, 
parts or links of the fucceflive motions of the organ of vifion. 
Thefe motions or configurations of the organs of fenfe differ 
from the fenforial motions to be defcribed hereafter, as they ap- 
pear to be limply contractions of the fibrous extremities of thofe 
organs, and in that refpeCt exaftly refemble the motions or con- 
tractions of the larger mufcles, as appears from the following 
experiment. Place a circular piece of red iilk about an inch in 
diameter on a fheet of white paper in a ftrong light, as in Plate 
I--look for a minute on this area, or till the eye becomes fome- 
what fatigued, and then, gently clofing your eyes, and (hading 
them with your hand, a circular green area of the fame appar- 
ent diameter becomes vifible in the clofed eye. This green 
area is the colour reverfe to the red area, which had been pre- 
Vol. I. C vioufly 10 
MOTIONS OF 
Sect. III. 2. 1, 
vioufly infpeCted, as explained in the experiments on ocular 
fpe&ra at the end of the work, and in Botanical Garden, P. I, 
additional note, No. I. Hence it appears, that a part of the ret- 
ina, which had been fatigued by contraction in one direction, 
relieves itfelf by exerting the antagonill fibres, and producing a 
contraCiion in an oppofite direction, as is common in the exer- 
tions of our mufcles. Thus when we are tired with long ac- 
tion of our arms in one direction, as in holding a bridle on a 
journey, we occafionally throw them into an oppofite pofition to 
relieve the fatigued mufcles. 
Mr. Locke has defined an idea to be " whatever is prefent to 
the mind but this would include the exertions of volition, 
and the fenfations of pleafure and pain, as well as thofe opera- 
tions of our fyftem, which acquaint us with external objects ; 
and is therefore too unlimited for our purpofe. Mr. Locke 
feems to have fallen into a further error, by conceiving, 
that the mind could form a general or abflraCt idea by its own 
operation, which was the copy of no particular perception ; as 
of a triangle in general, that was neither acute,., obtufe, nor 
right angled. The ingenious Dr. Berkley and Mb.- Hume have 
demonitrated, that fuch general ideas have no exiftence in na- 
ture, not even in the mind of their celebrated inventor. We 
(hall therefore take for granted at prefent, that our recollection 
or imagination of external objects confifts of a partial repetition 
of the perceptions, which were excited by thofe external ob- 
jects, at the time we became acquainted with them ; and that 
our reflex ideas of the operations of our minds are partial repeti- 
tions of thofe operations. 
II. The following article evinces that the organ of vifion con- 
fills of a fibrous part as well as of the nervous medulla, like oth- 
er white mufcles ; and hence, as it refembles the mufcular parts 
of the body in its ItruClure, we may conclude, that it muft re- 
femble them in pofleffing a power of being excited into animal 
motion. The fubfequent experiments on the optic nerve, and 
on the colours remaining in the eye, are copied from a paper on 
ocular fpedra publiflied in the feventy fixth volume of the Phi- 
lof. Tranf. by Dr. R. Darwin of Shrewlbury 5 which, as I fliall 
have frequent occafion to refer to, is reprinted in this work, 
SeCl. XL.-The retina of an ox's eye was fufpended in a glafs 
of warm water, and forcibly torn in a few places ; the edges of 
thefe parts appeared jagged and hairy, and did not contraCt and 
become fmooth like Ample mucus, when it is diltended till it 
breaks ; which evinced that it confilted of fibres. This fibrous 
conftruftion became Hill more diltinCt to the fight by adding 
fome caufiic alkali to the water ; as the adhering mucus was 
firft SECT.IIL3. 1. 
THE RETINA. 
11 
firft eroded, and the hair like fibres remained floating-in the vef- 
fel. Nor does the degree of tranfparency of the retina invali- 
date this evidence of its fibrous ftructure, fince Leeuwenhoek 
has (hewn, that the cryftaline humour itfelf confifts of fibres. 
Arc. Nat. V. I. 70. 
Hence it appears, that as the mufcles confift of larger fibres 
intermixed with a fmaller quantity of nervous medulla, the or- 
gan of vifion confifts of a greater quantity of nervous medulla 
intermixed with fmaller fibres. It is probable that the locomo- 
tive mufcles of microfcopic animals may have greater tenuity 
than thefe of the retina ; and there is reafon to conclude from 
analogy, that the other immediate organs of fenfe, as the portio 
mollis of the auditory nerve, and the rete mucofum of the Ikin, 
poflefs a fi'milarity of ftru£ture with the retina, and a fimilar 
power of being excited into animal motion. 
III. The fubfequent articles fhew, that neither mechanical 
impreflions, nor chemical combinations of light, but that the 
animal activity of the retina conftitutes vifion. 
1. Much has been conjetftured by philosophers about the 
momentum of the rays of light; to fubjecft this to experiment 
a very light horizontal balance was conftrudted by Mr. Michel, 
with about an inch fquare of thin leaf-copper fufpended at each 
end of it, as defciibcd in Dr. Prieftley's Hiftory of Light and 
Colours. The focus of a very large convex mirror was thrown 
by Dr. Powel, in his lectures on experimental philofophy, in 
my prefence, on one wing of this delicate balance, and it reced- 
ed from the light ; thrown on the other wing, it approached 
towards the light, and this repeatedly ; fo that no fenfible im- 
pulfe could be obferved, but what might well be aferibed to the 
afeent of heated air. 
Whence it is reafonable to conclude, that the light of the day 
muft be much too weak in its dilute ftate to make any mechan- 
ical impreflion on fo tenacious a fubllance as the retina of the 
eye.-Add to this, that as the retina is nearly tranfparent, it 
could therefore make lefs refiftance to the mechanical impulfe 
of light; which, according to the obfervations related by Mr. 
Melvil in the Edinburgh Literary Eflays, only communicates 
heat, and fhould therefore only communicate momentum, 
where it is obftrutfted, reflected, or refracted From whence 
alfo may be collected the final caufe of this degree of tranfpar- 
ency of the retina, viz. left by the focus of ftronger lights, heat 
and pain fhould have been produced in the retina, inftcad of 
that ftimulus which excites it into animal motion. 
2. On looking long on an area of fcarlet filk of about an inch 
in diameter laid on white paper, as in Plate I. the fcarlet colour 
becomes 12 
MOTIONS OF 
Sect. III. 3. 3. 
becomes fainter, till at length it entirely vanifhes, though the 
eye is kept uniformly and Readily upon it. Now if the change 
or motion of the retina was a mechanical impreflion, or a chem- 
ical tinge of coloured light, the perception would every minute 
become Rronger and Rronger,-whereas in this experiment it 
becomes every inRant weaker and weaker. The fame circum- 
Rance obtains in the continued application of found, or of fapid 
bodies, or of odorous ones, or of tangible ones, to their adapted 
organs of fcnfe. 
Thus when a circular coin, as a (hilling, is prefled on the 
palm of the hand, the fenfe of touch is mechanically compreif- 
ed ; but it is the Rimulus of this preflure that excites the organ 
of touch into animal action, which conRitutes the perception of 
hardnefs and of figure : for in fome minutes the perception 
ceafes, though the mechanical preflure of the object remains. 
3. Make with ink on white paper a very black fpot about half 
an inch in diameter, with a tail about an inch in length, fo as 
to refemble a tadpole, as in Plate II. ; look ReadfaRly for a 
minute on the centre of this fpot, and, on moving the eye a lit- 
tle, the figure of the tadpole will be feen on the white part of 
the paper ; which figure of the tadpole will appear more lumi- 
nous than the other part of the white paper ; which can only 
be explained by fuppofing that part of the retina, on which the 
tadpole was delineated, to have become more fenfible to light 
than the other parts of it, which were expofed to the white 
paper; and not from any idea of mechanical impreflion or 
chemical combination of light with the retina. 
4. When any'one turns round rapidly, till he becomes dizzy, 
and falls upon the ground, the fpeftra of the ambient objects 
continue to prefent themfelves in rotation, and he feems to be- 
hold the objects Rill in motion. Now if thefe fpedtra were im- 
preflions on a paflive organ, they either muR continue as they 
were received laR, or not continue at all. 
5. Place a piece of red filk about an inch in diameter on a 
fheet of white paper in a Rrong light, as in Plate I. ; look Read- 
ily upon it from the diflance of about half a yard for a minute ; 
then clofing your eye-lids, cover them with your hands and 
handkerchief, and a green fpeftrum will be feen in your eyes 
refembling in form the piece of red filk. After fome feconds 
of time the fpe&rum will difappear, and in a few more feconds 
will reappear ; and thus alternately three or four times, if the 
experiment be well made, till at length it vanifhes entirely. 
6. Place on a fheet of white paper a circular piece of blue 
filk, about four inches in diameter, in the funfliine ; cover the 
center of this with a circular piece of yellow filk, about three 
„ inches Sect. III. 4. 1. 
THE RETINA. 
13 
inches in diameter ; and the centre of the yellow filk with a 
circle of pink filk, about two inches in diameter ; and the cen- 
of the pink filk with a circle of green filk, about one inch in 
. ,n meter ; and the centre of this with a circle of indigo, about 
naif an inch in diameter ; make a fmall fpeck with ink in the 
very centre of the whole, as in Plate III. look fteadily for a min- 
ute on this central fpot, and then clofing your eyes, and applying 
your hand at about an inch diftance before them, fo as to pre- 
vent too much or too little light from palling through the eye- 
lids, and you will fee the moft beautiful circles of colours that 
imagination can conceive ; which are moft refemLled by the 
colours occafioned by pouring a drop or two of oil on a ftill 
lake in a bright day. But thefe circular irifes of colours are 
not only different from the colours of the filks above mention- 
ed, but are at the fame time perpetually changing as long a& 
they exift. 
From all thefe experiments it appeals, that thefe fpedtra ill 
the eye are not owing to the mechanical impulfe of light im- 
preffed on the retina ; nor to its chemical combination with 
that organ ; nor to the abforption and emiffion of light, as is 
fuppofed, perhaps erroneoully, to take place in calcined (hells 
and other phofphorefcent bodies, after having been expofed to 
the light : for in all thefe cafes the fpeftra in the eye ihould ei- 
ther remain of the fame colour, or gradually decay, when the 
object is withdrawn ; and neither their evanefcence during the 
prefence of the object, as in the fecond experiment, nor their 
change from dark to luminous, as in the third experiment, nor 
their rotation, as in the fourth experiment, nor the alternate 
prefence and evanefcence of them, as in the fifth experiment, 
nor the perpetual change of colours of them, as in the laft ex- 
periment, could exift. 
IV. The fubfequent articles (hew, that thefe animal motions 
or configurations of our organs of fenfe conftitutc our ideas. 
1. If any one in the dark preffes the ball of his eye, by ap- 
plying his finger to the external corner of it, a luminous appear- 
ance is obferved ; and by a fmart ftroke on the eye great flaihes 
of fire are perceived. (Newton's Optics.) So when the arteries, 
that are near the auditory nerve, make ftronger pulfations than 
ufual, as in fome fevers, an undulating found is excited in the 
ears. Hence it is not the prefence of the light and found, but 
^he motions of the organ, that are immediately necefl'ary to con- 
.Jtute the perception or idea of light and found. 
2. During the time of deep, or in delirium, the ideas of im- 
agination are miftaken for the perceptions of external objects ; 
whence it appears, that thefe ideas of imagination are no other 
than 14 
MOTIONS OF 
Sect. III. 4. 3. 
than a reiteration of thofe motions of the organs of fenfe, which 
were originally excited by the ftimulus of external obje&s : and 
in our waking hours the fimple ideas, that we call up by recoi 
ledlion or by imagination, as the colour of red, or the fmell of 
a rofe, are exact refemblances of the fame fimple ideas from 
perception ; and in conference mull be a repetition of thofe 
very motions. 
3. The difagreeable fenfation called the tooth-edge is origin- 
ally excited by the painful jarring of the teeth in biting the edge 
of the glafs, or porcelain cup, in which our food was given us 
in our infancy, as is further explained in the Section XVI, 10, 
on Inftinft.-This difagreeable fenfation is afterwards excited 
not only by a repetition of the found, that was then produced, 
but by imagination alone, as I have myfelf frequently experien- 
ced ; in this cafe the idea of biting a china cup, when I imagine 
it very diftintftly, or when I fee another perfon bite a cup or 
glafs, excites an actual pain in the nerves of my teeth. So that 
this idea and pain feem to be nothing more than the reiterated 
motions of thofe nerves, that were formerly fo difagreeably af- 
fected. 
Other ideas that are excited by imagination or recollection 
in many inftances produce fimilar effects on the conftitution, as 
©ur perceptions had formerly produced, and are therefore un- 
doubtedly a repetition of the fame motions. A ftory which the 
celebrated Baron Van Swieten relates of himfelf is to this pur- 
pofe. He was prefent when the putrid carcafs of a dead dog 
exploded with prodigious ftench ; and fome years afterwards, 
accidentally riding along the fame road, he was thrown into the 
fame ficknefs and vomiting by the idea of the ftench, as he had 
before experienced from the perception of it. 
4. Where the organ of fenfe is totally deftroyed, the ideas 
which were received by that organ feem to perifh along with it, 
as well as the power of perception. Of this a fatisfaCtory in- 
ftance has fallen under my obfervation. A gentleman about 
fixty years of age had been totally deaf for near thirty years : 
he appeared to be a man of good underftanding, and amufed 
himfelf with reading, and by converfing either by the ufe of the 
pen, or by figns made with his fingers, to reprefent letters. I 
cbferved that he had fo far forgot the pronunciation of the lan- 
guage, that when he attempted to fpeak, none of his words had 
diftinCt articulation, though his relations could fometimes un- 
derftand his meaning. But, which is much to the point, he af- 
fured me, that in his dreams he always imagined that people 
converted with him by figns or writing, and never that he 
heard any one fpeak to him. From hence it appears, that with 
the Sect. III. 5. 1. 
THE RETINA. 
15 
the perceptions of founds he has alfo loft the ideas of them ; 
though the organs of fpeech ftill retain fomewhat of their ufual 
habits of articulation: 
This obfervation may throw fome light on the medical treat- 
ment of deaf people ; as it may be learnt from their dreams 
whether the auditory nerve be paralytic, or their deafnefs be 
owing to fome defetft of the external organ. 
It rarely happens that the immediate organ of vifion is per- 
fectly deftroyed. The moft frequent caufes of blindnefs are 
occafioned by defects of the external organ, as in catarafts and 
obfufcations of the cornea. But I have had the opportunity of 
converting with two men, who had been fome years blind ; one 
of them had a complete gutta ferena, and the other had loft the 
whole fubftance of his eyes. They both told me that they did 
not remember to have ever dreamt of vifible objeCts, fincc the 
total lofs of their fight. 
V. Another method of difcovering that our ideas are animal 
motions of the organs of fenfe, is from confidering the great 
analogy they bear to the motions of the larger mufcles of the 
body. In the following articles it will appear that they are orig- 
inally excited into action by the irritation of external objects 
like our mufcles ; are aflbeiated together like our mufcular mo- 
tions ; ad in limilar time with them ; are fatigued by continu- 
ed exertion like them ; and that the organs of fenfe are fubjebt 
to inflammation, numbnefs, palfy, convulfion, and the defeats 
of old age, in the fame manner as the mufcular fibres. 
i. All our perceptions or ideas of external objects are uni- 
verfally allowed to have been originally excited by the ftimulus 
of thofe external objeefts ; and it will be Ihewn in a fucceeding 
fedtion, that it is probable that all our mufcular motions, as well 
thofe that are become voluntary as thofe of the heart and glan- 
dular fyftem, were originally in like manner excited by the ftim- 
ulus of fomething external to the organ of motion. 
2- Our ideas are alfo aflbeiated together after their produc- 
tion precifely in the fame manner as our mufcular motions; 
which will likewife be fully explained in the fucceeding feclion. 
3. The time taken up in performing an idea is likewife much 
the fame as that taken up in performing a mufcular motion. A 
mufician can prefs the keys of an harpfichord with his fingers 
in the order of a tune he has been accuftomed to play, in as 
little time as he can run over thofe notes in his mind. So wc 
many times in an hour cover our eye-balls with our eye-lids 
without perceiving that we are in the dark ; hence the percep- 
tion or idea of light is not changed for that of darknefs in fo 
fmall a time as the twinkling of an eye ; fo that in this cafe the 
mufcular 16 
MOTIONS OF 
Sect. III. 5. 4. 
mufcular motion o£ the eye-lid is performed quicker than the 
perception of light can be changed for that of darknefs.-So if 
a fire-Rick be whirled round in the dark, a luminous circle ap- 
pears to the obferver; if it be whirled fomewhat flower, this 
circle becomes interrupted in one part; and then the time taken 
up in fuch a revolution of the ftick is the fame that the obferver 
ufes in changing his ideas : thus the of Homer> 
the long fnadow of the flying javelin, is elegantly defigned to 
give us an idea of its velocity, and not of its length. 
4. The fatigue that follows a continued attention of the mind 
to one object is relieved by changing the fubjecl of our thoughts; 
as the continued movement of one limb is relieved by moving 
another in its Read. Whereas a due cxercife of the faculties of 
the mind fl.rengthens and improves thofe faculties, whether of 
imagination or recollection; as the exercife of our limbs in 
dancing or fencing incrcafcs the ftrength and agility cf the muf- 
cles thus employed. 
5. If the mufcles of any limb are inflamed, they do not move 
without pain ; fo when the retina is inflamed, its motions alfo 
are painful. Hence light is as intolerable in this kind of oph- 
thalmia, as preffure is to the finger in the paronychia. In this 
difeafe the patients frequently dream of having their eyes pain- 
fully dazzled ; hence the idea of ftrong light is painful as well 
as the reality. The firft of thefe faCts evinces that our percep- 
tions are motions of tlic organs of fenfe j and the latter, that our 
imaginations are alfo motions of the fame organs. 
6. The organs of fenfe, like the moving mufcles, are liable te 
become benumbed, or lefs fenfible, from compreflion. Thus, 
if any perfon on a light day looks on a white wall, he may per- 
ceive the ramifications of the optic artery, at every pulfation of 
it, reprefented by darker branches on the white wall; which is 
evidently owing to its comprefling the retina during the diaftole 
of the artery. Sauvages Nofolog. 
7. The organs of fenfe and the moving mufcles are alike lia- 
ble to be affected with palfy, as in the gutta ferena, and in fome 
cafes of deafnefs ; and one fide of the face has fometimes loft 
its power of fenfation, but retained its power of motion j other 
parts of the body have loft their motions, but retained their fen- 
fation, as in the common hemiplegia ; and in other inftances 
both thefe powers have perifhed together. 
8. In fome convulfive difeafes a delirium or infanlty fuper- 
venes, and the convulfions ceafe; and converfely the convul- 
fions fhall fupervene, and the delirium ceafe. Of this I have 
been a witnefs many times in a day in the paroxyfms of violent 
epilepfies; which evinces that one kind of delirium is a convul. 
fion Sect. III. p 9. 
THE RETINA*. 
17 
fion of the organs of fenfe, and that our ideas are tile motions 
of thefe organs : the fubfequent cafes will illuftrate this obfer- 
ration. 
Mifs G , a fair young lady, with light eyes and hair, was 
feized with moft violent convullions of her limbs, with outra- 
geous hiccough, and moft vehement efforts to vomit: after near 
an hour was elapfed this tragedy ceafed, and a calm talkative 
delirium fupervened for about another hour; and thefe relieved 
each other a.t intervals during the greateft part of three or four 
days. After having carefully confidered this difeafe, I thought 
the convullions of her ideas lefs dangerous than thofe of her 
mufcles; and having in vain attempted to make any opiate 
continue in her ftomach, an ounce of laudanum was rubbed along 
the fpine of her back, and a dram of it was ufed as an enema ; 
by this medicine a kind of drunken delirium was continued ma- 
ny hours ; and when it ceafed the convullions did not return ; 
and the lady continued well many years, except fome {lighter re- 
lapfes, which were relieved in the fame manner. 
Mifs H , an accomplilhed young lady, with light eyes and 
hair, was feized with convulfions of her limbs, with hiccough, 
and efforts to vomit, more violent than words can exprefs; thefe 
continued near an hour, and were fucceeded with a cataleptic 
fpafm of one arm, w^th the hand applied to her head ; and af- 
ter about twenty minutes thefe fpafms ceafed, and a talkative 
reverie fupervened for near an hour, from which no violence, 
which it was proper to ufe, could awaken her. Thefe periods 
of convulfions, firft of the mufcles, and then of the ideas, re- 
turned twice a day for feveral weeks ; and were at length re- 
moved by great dofes of opium, after a great variety of other 
medicines and applications had been in vain experienced. This 
lady was fubjed: to frequent relapfes, once or twice a year for 
many years, and was as frequently relieved by the fame method. 
Mifs W , an elegant young lady, with black eyes and 
hair, had fometimes a violent pain of her fide, at other times a 
moft painful ftrangury, which were every day fucceeded by de- 
lirium ; which gave a temporary relief to the painful fpafms. 
After the vain exhibition of variety of medicines and applica- 
tions by different phyficians, for more than a twelvemonth, fhe 
was directed to take fome dofes of opium, which were gradually 
increafed, by which a drunken delirium was kept up for a day 
or two, and the pains prevented from returning. A flefh diet, 
with a little wine or beer, inftead of the low regimen the had 
previoufly ufed, in a few weeks completely eftablifhed her health ; 
which, except a few relapfes, has continued for many years. 
9. Laftly, as we advance in life all the parts of the body be- 
Vol. I. I) come 18 
MOTIONS OF 
Sect. III. 6. t. 
come more rigid, are rendered lefs fufceptiblc of new habits of 
motion, though they retain thofe that were before eftabliflied. 
This is fenfibly obferved by thofe who apply themfelves late in 
life to mufic, fencing, or any of the mechanic arts. In the fame 
manner many elderly people retain the ideas they had learned 
early in life, but find great difficulty in acquiring new trains of 
memory ; infomuch that in extreme old age we frequently fee 
a forgetfulnefs of the bufinefs of yeflerday, and at the fame time 
a circumftantial remembrance of the amufements of their youth ; 
till at length the ideas of recolleflion and activity of the body 
gradually ceafe together,-fuch is the condition of humanity ! 
-and nothing remains but the vital motions and fenfations. 
VI. i. In oppofition to this doctrine of the production of 
our ideas, it may be alked, if fome of our ideas, like other ani- 
mal motions, are voluntary, why can we not invent new ones, 
that have not been received by perception ? The anfwer will be 
better underftood after having pcrufed the fucceeding feCtion, 
■where it will be explained, that'the mufcular motions likewife 
arc originally excited by the ftimulus of bodies external to the 
moving organ ; and that the will has only the power of repeat- 
ing the motions thus excited. 
2. Another objeCtor may alk, Can the motion of an organ of 
fenfe refemble an odour or a colour ? To which I can only an- 
fwer, that it has not been demonitrated tfiat any of our ideas re- 
femble the objects that excite them ; it has generally been be- 
lieved that they do not j but this ffiall be difcufled at large in 
SeCt. XIV. 
3. There is another objection that at firfl view would feem 
lefs eafy to furmount. After the amputation of a foot or a finger, 
it has frequently happened, that an injury being offered to 
the (lump of the amputated limb, whether from cold air, 
too great preffure, or other accidents, the patient has com- 
plained of a fenfation of pain in the foot or finger, that was 
cut off. Docs not this evince that all our ideas are excited in 
the brain, and not in the organs of fenfe ? This objection is 
anfwered, by obferving that our ideas of the ffiape, place, and 
folidity of our limbs, are acquired by our organs of touch and 
of fight, which are fituated in our fingers and eyes, and not by 
any fenfations in the limb itfelf. 
In this cafe the pain or fenfation, which formerly has arifen 
in the foot or toes, and been propagated along the nerves to the 
central part of the fenforium, was at the fame time accompanied 
with a vifible idea of the ffiape and place, and with a tangible 
idea cf the folidity of the affeCted limb : now when thefe nerves 
are afterwards affeCted by any injury done to the remaining 
flump Sect. III. 6. 4. 
THE RETINA. 
19 
ftump with a fimilar degree or kind of pain, the ideas of die 
fhape,*place, or folidity of the loft limb, return by aflbciation ; 
as thele ideas belong to the organs of fight and touch, on 
which they were firft excited. 
4. If you wonder what organs of fenfe can be excited into 
motion, when you call up the ideas of wifdom or benevolence, 
which Mr. Locke has termed abftrafted ideas; I alk you by 
what organs of fenfe you firft became acquainted with thefe 
ideas ? And the anfwer will be reciprocal; for it is certain that 
all our ideas were originally acquired by our organs of fenfe ; 
for whatever excites our perception muft be external to the or- 
gan that perceives it, and we have no other inlets to knowledge 
but by our perceptions : as will be further explained in Section 
XIV. and XV. on the Productions and Clafles of ideas. 
VII. If our recolleClion or imagination be not a repetition of 
animal movements, I alk, in my turn, What is it ? You tell me 
it confifts of images or pictures of things. Where is this ex- 
tenfive canvas hung up ? or where are the numerous receptacles 
in which thofe are deposited ? or to what clfe in the animal 
fyftem have they any fimilitude ? 
That pleafing picture of objeCts, reprefented in miniature on 
the retina of the eye, feems to have given rife to this illufive or- 
atory 1 It was forgot that this reprefentation belongs rather to 
the laws of light, than to thofe of life; and may with equal ele- 
gance be feen in the camera obfcura as in the eye ; and that the 
picture vanifhes for ever, when the objeCt is withdrawn. 
SECT. 20 
ANIMAL CAUSATION. 
Sect. IV. 
SECT. IV. 
LAWS OF ANIMAL CAUSATION. 
I. The fibres, which conftitute the mufcles and organs of 
fenfc, poffefs a power of contraction. The circumftances at- 
tending the exertion of this power of contraction conftitute 
the laws of animal motion, as the circumftances attending the 
exertion of the power of attraction conftitute the laws of 
motion of inanimate matter. 
II. The fpirit of animation is the immediate caufe of the 
contraCtion of animal fibres, it refides in the brain and nerves, 
and is liable to general or partial diminution or accumulation. 
III. The ftimulus of bodies external to the moving organ is 
the remote caufe of the original contraCtions of animal fibres. 
IV. A certain quantity of ftimulus produces irritatioo, which 
is an exertion of the fpirit of animation exciting the fibres into 
contraCtion. 
V. A certain quantity of contraCtion of animal fibres, if it be 
perceived at all, produces pleafure ; a greater or lefs quantity of 
contraction, if it be perceived at all, produces pain ; thefe con- 
ftitute fenfation. 
VI. A certain quantity of fenfation produces defire or aver- 
fion; thefe conftitute volition. 
VII. All animal motions which have occurred at the fame 
time, or in immediate fucceflion, become fo connected, that 
when one of them is reproduced, the other has a tendency to 
accompany or fucceed it. When fibrous contraCtions fucceed 
or accompany other fibrous contraCtions, the connexion is term- 
ed aflbeiation ; when fibrous contraCtions fucceed fenforial mo- 
tions, the connexion is termed caufation ; when fibrous and fen- 
forial motions reciprocally introduce each other, it is termed 
catenation of animal motions. All thefe connexions are faid to 
be produced by habit, that is, by frequent repetition. Thefe 
laws of animal caufation will be evinced by numerous fads, 
which occur in our daily exertions; and will afterwards be em- 
ployed to explain the more recondite phenomena of the produc- 
tion, growth, difeafes, and decay of the animal fyftem. 
SECT. Sect. V. 1. 
SENSORIAL FACULTIES. 
21 
SECT. V. 
QJ THE FOUR FACULTIES OR MOTIONS OF THE SENSORIUM. 
I. Fourfenforialpowers. 2. Irritation, fenfation, volition, affect- 
ation defined. 3. fenforial motions difiinguijhedfrom fibrous mo- 
tions. 
I. The fpirit of animation has four different modes of ac- 
tion, or in other words the animal fenforium poffeffes four dif- 
ferent faculties, which are oecafionally exerted, and caufe all 
the contractions of the fibrous parts of the body. Thef« are 
the faculty of caufing fibrous contractions in confequence of 
the irritations excited by external bodies, in confequence of the 
fenfations of pleafure or pain, in confequence of volition, and in 
confequence of the aflbeiations of fibrous contraCtions with oth- 
er fibrous contraCtions, which precede or accompany them. 
Thefe four faculties of the fenforium during their inactive Rate 
are termed irritability, fenfibility, voluntarily, and aflbeiability ; 
in their aCtive ftate they are termed as above, irritation, fenia- 
tion, volition, aflbeiation. 
2. Irritation is an exertion or change of fome extreme 
part of the fenforium refiding in the mufcles or organs of fenfe, 
in confequence of the appulfes of external bodies. 
Sensation is an exertion or change of the central parts of the 
fenforium, or of the whole of it, beginning at fome of thofe ex- 
treme parts of it, which refide in the mufcles or organs of fenfe. 
Volition is an exertion or change of the central parts of the 
fenforium, or of the whole of it, terminating in fome of thofe ex- 
treme parts of it, which refide in the mufcles or organs of fenfe. 
Association is an exertion or change of fome extreme part 
of the fenforium refiding in the mufcles or organs of fenfe, in 
confequence of fome antecedent or attendant fibrous contrac- 
tions. 
3. Thefe four faculties of the animal fenforium may at the 
time of their exertions be termed motions without impropriety 
of language ; for we cannot pafs from a ftate of infenfibility or 
inaCtion to a ftate of fenfibility or of exertion without fome 
change of the fenforium, and every change includes motion. 
We (hall therefore fometimes term the above defcribed faculties 
JenJbrial motions to diftinguifh them from fibrous motions ,* 
which latter expreflion includes the motions of the mufcles and 
organs of fenfe. 
The aCtive motions of the fibres, whether thofe of the mufcles 
or 22 
SENSORIAL FACULTIES. 
Sect. V. 3. 
or organs of fenfe, are probably Ample contraCtions ; the fibres 
being again elongated by antagonift mufcles, by circulating 
fluids, or fometimes by elaftic ligaments, as in the necks of 
quadrupeds. The fentorial motions, which conflitute the ton- 
fations of pleafure or pain, and which conftitute volition, and 
which caufe the fibrous contractions in confequence of irritation 
or of aflbciation, are not here fuppofed to be fluctuations or re- 
fluCtuations of the fpirit of animation ; nor are they fuppofed 
to be vibrations or revibrations, nor condenfations or equilibra- 
tions of it j but to be changes or motions of it peculiar to life. 
SECT. Sect. VI. 1. 1. 
FIBROUS CONTRACTIONS. 
23 
SECT. VI. 
OF THE FOUR CLASSES OF FIBROUS MOTIONS. 
I. Origin of fibrous contraBions. II. Difiribution of them into four 
claffes > irritative motions} fenfitive motions > voluntary motions, and 
officiate motions, defined. 
I. All the fibrous contraCtions of animal bodies originate 
from the fenforium, and refolve themfelves into four claffes, cor- 
refpondent with the four powers or motions of the fenforium 
above defcribed, and from which they have their caufation. 
i. Thefe fibrous contractions were originally caufed by the 
irritations excited by objeCts, which are external to the moving 
organ. As the pulfations of the heart are owing to the irrita- 
tions excited by the ftimulus of the blood ; and the ideas of per- 
ception are owing to the irritations excited by external bodies. 
2. But as painful or pleafurable fenfations frequently accom- 
panied thofe irritations, by habit thefe fibrous contraCiions be- 
came caufable by the fenfations, and the irritations ceafed to be 
neceffary to their production. As the fecretion of tears in grief 
is caufed by the fenfation of pain ; and the ideas of imagina- 
tion, as in dreams or delirium, are excited by the pleafure or 
pain, with which they were formerly accompanied. 
3. But as the efforts of the will frequently accompanied 
thefe painful or pleafurable fenfations, by habit the fibrous con- 
traCtions became caufable by volition ; and both the irritations 
and fenfations ceafed to be neceffary to their production. As 
the deliberate locomotions of the body, and the ideas of recol- 
lection, as when we will to repeat the alphabet backwards. 
4. But as many of thefe fibrous contraCtions frequently ac- 
companied other fibrous contraCtions, by habit they became 
caufable by their aflbciations with them ; and the irritations, 
fenfations, and volition, ceafed to be neceffary to their produc- 
tion. As the aCtions of the mufcles of the lower limbs in fen- 
cing are affociated with thofe of the arms ; and the ideas of fug- 
geltion are affociated with other ideas, which precede or accom- 
pany them ; as in repeating carelefsly the alphabet in its ufual 
order after having began it. 
IL We fhall give the following names to thefe four claffes of 
fibrous motions, and fubjoin their definitions. 
1. Irritative motions. That exertion or change of the fenfo- 
rium, which is caufed by the appulfes of external bodies, either 
fimply fubfides, or is fucceeded by fenfation, or it produces 
fibrous 24 
FIBROUS CONTRACTIONS. 
Sect. VI. 2. 2. 
fibrous motions ; it is termed irritation, and irritative motions 
are thofe contractions of the mufcular fibres, or of the organs 
of fenfe, that are immediately confequent to this exertion or 
change of the fenforium. 
2. Senfitive motions. That exertion or change of the fenfo- 
rium, which conftitutes pfeafure or pain, either fimply fubfides, 
or is fucceeded by volition, or it produces fibrous motions ; it 
is termed fenfation, and the fenfitive motions are thofe contrac- 
tions of the mufcular fibres, or of the organs of fenfe, that are 
immediately confequent to this exertion or change of the fenfo- 
rium. 
3. Voluntary motions. That exertion or change of the fen- 
forium, which conftitutes defire or averfion, either fimply fub- 
fides, or is fucceeded by fibrous motions; it is then termed vo- 
lition, and voluntary motions are thofe contraCtions of the muf- 
cular fibres, or of the organs of fenfe, that are immediately con- 
fequent to this exertion or change of the fenforium. 
4. Afibciate motions. That exertion or change of the fen- 
forium, which accompanies fibrous motions, either fimply fub- 
fides, or is fucceeded by fenfation or volition, or it produces 
other fibrous motions ; it is then termed aflbciation, and the af- 
fociate motions are thofe contractions of the mufcular fibres, or 
of the organs of fenfe, that are immediately confequent to this 
exertion or change of the fenforium. 
SECT. Sect. VII. 1. 1. 
IRRITATIVE MOTIONS. 
25 
SECT. VII. 
OF IRRITATIVE MOTIONS. 
I. I. Some mufcular motions are excited by perpetual irritations. 2. 
Others more frequently by fenfations. 3. Others by volition. 
Cafe of involuntary JI retchings in paralytic limbs. 4. Some fen- 
fual motions are excited by perpetual irritations. $. Others more 
frequently by fenfation or volition. IL 1. Mtifcular motions ex- 
cited byperpetual irritations occafionally become obedient to fenfation 
and to volition. 2. And the fenfual motions. 111. 1. Other muf- 
cular motions are affociated vuith the irritative ones. 2. And other 
ideas vnth irritative ones. Of letters, language, hieroglyphics. 
Irritative ideas exijl without our attention to them. 
I. 1. Many of our mufcular motions are excited by perpet- 
ual irritations, as thofe of the heart and arterial fyftem by the 
circumfluent blood. Many other of them are excited by inter- 
mitted irritations, as thofe of the ftomach and bowels by the ali- 
ment we fwallow ; of the bile-duds by the bile ; of the kid- 
neys, pancreas, and many other glands, by the peculiar fluids 
they feparate from the blood ; and thofe of the laCIeal and oth- 
er abforbent veflels by the chyle, lymph, and moifture of the at- 
mofphere. Thefe motions are accelerated or retarded, as their 
correfpondent irritations are increafcd or diminilhed, without 
our attention or confcioufnefs, in the fame manner as die vari- 
ous fecretions of fruit, gum, refiu, wax, and honey, are produ- 
ced in the vegetable world, and as the juices of the earth and 
the moifture of the atmofphere are abforbed by their roots and 
foliage. * 
2. Other mufcular motions, that are moft frequently con- 
nected with our fenfations, as thofe of the fphinCters of the 
bladder and anus, and the mufeuli ereCtores penis, were origin- 
ally excited into motion by irritation, for young children make 
water, and have other evacuations without attention to thefe cir- 
cumftances ; " et primis etiam ab incunabulis tenduntur faepi- 
us puerorum penes, amore nondum expergefaCto." So the nip- 
ples of young women are liable to become turgid by irritation, 
long before they are in a fituation to be excited by the pleaiure 
of giving milk to the lips of a child. 
3. The contractions of the larger mufcles of our bodies, that 
are moft frequently connected with volition, were originally ex- 
cited into aCtion by internal irritations : as appears from the 
ftretching or yawning of all animals after long ileep. In the 
Vol. I. E beginning 26 
IRRITATIVE 
Sect. VII. 1. 4. 
beginning of fome fevers this irritation of the mufcles produces 
perpetual ftretching and yawning ; in other periods of fever an 
univerfal reftleflhefs arifes from the fame caufe, the patient 
changing the attitude of his body every minute. The repeated 
itruggles of the foetus in the uterus muff be owing to this inter- 
nal irritation : for the feetus can have no other inducement to 
move its limbs but the tsedium or irkfomenefs of a continued 
pofture. 
The following cafe evinces, that the motions of ftretching the 
limbs after a continued attitude are not always owing to 
the power of the will. Mr. Dean, a mafon, of Auftry, in 
Leicefterfhire, had the fpine of the third vertebra of the back 
enlarged ; in fome weeks his lower extremities became feeble, 
and at length quite paralytic : neither the pain of blifters, the 
heat of fomentations, nor the utmoft efforts of the will could 
produce the leaft motion in thefe limbs ; yet twice or thrice a 
day for many months his feet, legs, and thighs, were affeCted 
for many minutes with forcible ftretchings, attended with the 
fenfaticn of fatigue ; and he at length recovered the ufe of his 
limbs, though the fpine continued protuberant. The fame cir- 
cumftance is frequently feen in a lefs degree in the common 
hemiplegia ; and whan this happens, I have believed repeated 
and ftrong fliocks of eleCtricity to have been of great advantage. 
4. In like manner the various organs of fenfe are originally 
excited into motion by various external ftimuli adapted to this 
purpofe, which motions are termed perceptions or ideas ; and 
many of thefe motions during our waking hours are excited by 
perpetual irritation, as thofe of the organs of hearing and of 
touch. The former by the conftant low indiftinCt noifes that 
murmur around us, and the latter by the weight of our bodies 
on the parts which fupport them ; and by the unceafing varia- 
tions of the heat, moifture, and preffure of the atmofphere ; 
and thefe fenfual motions, precifely as the mufcular one above 
mentioned, obey their correfpondcnt irritations without our at- 
tention or confcioufnefs. 
5. Other clafTes of our ideas are more frequently excited by 
our fenfations of pleafure or pain, and others by volition : but 
that thefe have all been originally excited by ftimuli from exter- 
nal objects, and only vary in their combinations or feparations, 
has been fully evinced by Mr. Locke : and are by him termed 
the ideas of perception in contradiftinCtion to thofe, which he 
calls the ideas of reflection. 
II. 1. Thefe mufcular motions, that are excited by perpetual 
irritation, are neverthelefs occafionally excitable by the fenfations 
of pleafure ox pain, or by volition ; as appears by the palpita- 
tion Sect. VII. 2. 2. 
MOTIONS. 
27 
tion of the heart from fear, the increafed fecretion of faliva at 
the fight of agreeable food, and the glow on the fkin of thofe 
who are afhamed. There is an inltance told in the Phiiofophi- 
cal Tranfa&ions of a man, who could for a time flop the mo- 
tion of his heart when he pleafed ; and Mr. D. has often told 
me, he could fo far increafe the periftaltic motion of his bowels 
by voluntary efforts, as to produce an evacuation by ftool at any 
time in half an hour. 
2. In like manner the fenfual motions, or ideas, that are ex- 
cited by perpetual irritation, are neverthelefs occafionally exci- 
ted by fenfation or volition ; as in the night, when we liften 
under the influence of fear, or from voluntary attention, the 
motions excited in the organ of hearing by the whifpering of 
the air in our room, the pulfation of our own arteries, or the 
faint beating of a diltant watch, become objects of perception. 
III. i. Innumerable trains or tribes of other motions are af- 
fociated with thefe mufcular motions which are excited by irri- 
tation ; as by the ftimulus of the blood in the right chamber of 
the heart, the lungs are induced to expand themfelves ; and the 
peftoral and intercoftal mufcles, and the diaphragm, aft at the 
fame time by their affociations with them. And when the pha- 
rinx is irritated by agreeable food, the mufcles of deglutition are 
brought into action by affociation. Thus when a greater light 
falls on the eye, the iris is brought into action without our at- 
tention, and the ciliary procefs, when the focus is formed be- 
fore or behind the retina, by their affociations with the increaf- 
ed irritative motions of the organ of vifion. Many common 
actions of life are produced in a fnnilar manner. If a fly fettle 
on my forehead, whilft I am intent on my prefent occupation, 
I diflodge it with my finger, without exciting my attention or 
breaking the train of my ideas. 
2. In like manner the irritative ideas fuggeft to us many oth- 
er trains or tribes of ideas that are affociated with them. On 
this kind of connexion, language, letters, hieroglyphics, and ev- 
ery kind of fymbol, depend. The fymbols themfelves produce 
irritative ideas, or fenfual motions, which we do not attend to ; 
and other ideas, that are fucceeded by fenfation, are excited by 
their affociation with them. And as thefe irritative ideas make 
up a part of the chain of our waking thoughts, introducing oth- 
er ideas that engage our attention, though themfelves are unat- 
tended to, we find it very difficult to inveftigate by what flops 
many of our hourly trains of ideas gain their admittance. 
It may appear paradoxical, that ideas can exifl, and not be at- 
tended to ; but all our perceptions are ideas excited by irrita- 
tion, and fucceeded by fenfation. Now when thefe ideas exci- 
ted 28 
IRRITATIVE MOTIONS. 
Sect. VII. 3. 2. 
ted by irritation give us neither pleafure nor pain, we ceafe to 
attend to them. Thus whilft I am walking through that grove 
before my window, I do not run againft the trees or the benches, 
though my thoughts are ftrenuoully exerted on fome other ob- 
ject. This leads us to a diftindl knowledge of irritative ideas, 
for the idea of the tree or bench, which I avoid, exifts on my 
retina, and induces by aflbciation the action of certain locomo- 
tive mufcles ; though neither itfelf nor the actions of thofe muf- 
Cles engage my attention. 
Thus whilft we are converging on this fubjedt, the tone, note, 
and articulation of every individual word forms its correfpondent 
irritative idea omthe organ of hearing ; but we only attend to 
the aflbciated ideas, that are attached by habit to thefe irritative 
ones, and are fucceeded by fenfation ; thus when we read the 
words,« printing-press" we do not attend to the Ihape, fize, 
or exiftence of the letters which compofe thefe words, though 
each of them excites a correfpondent irritative motion of our 
organ of vifion, but they introduce by aflbciation our idea of the 
moft ufeful of modern inventions ; the capacious refervoir of 
human knc vledge, whofe branching ftreams diffufe fciences, 
aits, and morality, through all nations and all ages. 
SECT. Sect. VIII. 1.1. 
SENSITIVE MOTIONS. 
29 
SECT. VIII. 
OI- SENSITIVE MOTIONS. 
I. I. Zenfitive mufcular motions were originally excited into action 
by irritation. 2. Andfenfitive fenfual motions, ideas of imagine 
tion, dreams. II. I. Senfitive mufcular motions are occaftonally 
obedient to volition. 2. And fenjitive fenfual motions. III. I. 
Other mufcular motions are ajfociated with the fenftive ones. 2* 
And other fenfual motions. 
I. i. Many of the motions of our mufcles, that are excited 
into aft ion by irritation, are at the fame time accompanied with 
painful or plea furable fen fations ; and at length become by 
habit caufable by the fenfations. Thus the motions of the 
fphinfters of the bladder and anus were originally excited into 
aftion by irritation ; for young children give no attention to 
thefe evacuations j but as foon as they become fenfible of the 
inconvenience of obeying thefe irritations, they fuffer the water 
or excrement to accumulate, till it difagreeably affefts them ; 
and the aftion of thofe fphinfters is then in confequence of this 
difagreeable fenfation. So the fecretion of faliva, which in 
young children is copioufly produced by irritation, and drops 
from their mouths, is frequently attended with the agreeable 
fenfation produced by the maftication of tafteful food ; till at 
length the fight of fuch food to a hungry perfon excites into 
aftion thefe falival glands; as is feen in the Havering of hungry 
dogs. 
The motions of thofe mufcles, which are affefted by lafcivi- 
ous ideas, and thofe which are exerted in fmiling, weeping, 
ftarting from fear, and winking at the approach of danger to 
the eye, and at times the aftions of every large mufcle of the 
body become caufable by our fenfations. And all thefe motions 
are performed with ftrength and velocity in proportion to the 
energy of the fenfation that excites them, and the quantity of 
fenforial power. 
2. Many of the motions of our organs of fenfe, or ideas, that 
were originally excited into aftion by irritation, become in like 
manner more frequently caufable by our fenfations of pleafurc 
or pain. Thefe motions are then termed the ideas qf imagina- 
tion, and make up all the feenery and tranfaftions of our 
dreams. Thus when any painful or pleafurable fenfations pof- 
fefs us, as of love, anger, fear ; whether in our fleep or waking 
hours, the ideas, that have been formerly excited by the objefts 
of 30 
SENSITIVE MOTIONS. 
Sect. VIII. 2. r. 
of thefe fenfations, now vividly recur before us by their con- 
nexion with thefe fenfations themfelves. So the fair finding 
virgin, that excited your love by her prefence, whenever that 
fenfation recurs, riles before you in imagination ; and that with 
all the pleafing circumftances, that had before engaged your at- 
tention. And in ileep, when you dream under the influence of 
fear, all the robbers, fires, and precipices, that you formerly 
have feen or heard of, arife before you with terrible vivacity. All 
thefe fenfual motions, like the mufcular ones above mentioned, 
are performed with ftrength and velocity in proportion to the 
energy of the fenfation of pleafure or pain, which excites them, 
and the quantity of fenforial power. 
II. i. Many of thefe mufcular motions above defcribed, that 
are moft frequently excited by our fenfations, are neverthelefs 
occafionally caufable by volition ; for we can fmile or frown 
fpontaneoufly, can make water before the quantity or acrimony 
of the urine produces a difagreeable fenfation, and can volunta- 
rily mafticate a naufeous drug, or fwallow a bitter draught, 
though our fenfation would ftrongly difluade us. 
2. In like manner the fenfual motions, or ideas, that are moft 
frequently excited by our fenfations, are neverthelefs occafion- 
ally caufable by volition, as we can fpontaneoufly call up our 
laft night's dream before us, tracing it induftrioully Hep by Hep 
through all its variety of feenery and tranfaction ; or can volun- 
tarily examine or repeat the ideas, that have been excited by our 
difguft or admiration. 
III. i. Innumerable trains or tribes of motions are aflbeiated 
with thefe fenfitive mufcular motions above mentioned ; as when 
a drop of water falling into the wind-pipe difagreeably affects 
the air-veffels of the lungs, they are excited into violent action ; 
and with thefe fenfitive motions are affociated the actions of the 
peQoral and intercoftal mufcles, and the diaphragm ; till by 
their united and repeated fucceffions the drop is returned 
through the larinx. The fame occurs when any thingdifagree- 
ahly affedfs the noftrils, or the ftomach, or the uterus; variety 
of mufcles are excited by affociation into forcible action, not to 
be fuppreffed by the utmoft efforts of the will; as in Ineezing, 
vomiting, and parturition. 
2. In like manner with thefe fenfitive fenfual motions, or ideas 
of imagination, are aflbeiated many other trains or tribes of 
ideas, which by fome writers of metaphyfics have been claffed 
under the terms of refcmblance, caufation, and contiguity ; and 
will be more fuilv treated of hereafter. 
SECT. Sect. IX. 1. 1. 
VOLUNTARY MOTIONS. 
31 
SECT. IX. 
OF VOLUNTARY MOTIONS. 
I. I. Voluntary mufcular motions are originally excited by irritations. 
2. And voluntary ideas. Of reafon. II. I. Voluntary mufcular 
motions are occafionally caufable by fenfations. 2. And voluntary 
ideas. III. I. Voluntary mufcular motions are occafior.ally obe- 
dient to irritations. 2. And voluntary ideas, IV. I. Volun- 
tary mufcular motions are affociated with other mufcular motions. 
2. And voluntary ideas. 
When pleafure or pain afFecSt the animal fyftem, many of its 
motions both mufcular and fenfual are brought into adion; as 
was (hewn in the preceding fedion, and were called fenfitive 
motions. The general tendency of thefe motions is to ar re It 
and to poiTefs the pleafure, or to diflodge or avoid the pain : but 
if this cannot immediately be accomplished, defire or averfion 13 
produced, and the motions in confequence of this new faculty 
of the fenforium are called voluntary. 
I. 1. Thofe mufcles of the body that are attached to bones, 
have in general their principal connexions with volition, as I 
move my pen or raife my body. Thefe motions were original- 
ly excited by irritation, as was explained in the fedion on that 
fubjed, afterwards the fenfations of pleafure or pain, that accom- 
panied the motions thus excited, induced a repetition of them ; 
and at length many of them were voluntarily pradifed in fuc- 
celTion or in combination for the common purpofes of life, as 
in learning to walk, or to fpeak; and are performed with 
ftrength and velocity in proportion to the energy of the volition, 
that excites them, and the quantity of fenforial power. 
2. Another great clafs of voluntary motions confifts of the 
ideas of recollection. We will to repeat a certain train of ideas, 
as of the alphabet backwards; and if any ideas that do not be- 
long to this intended train, intrude themfelves by other connex- 
ions, we will to rejed them, and voluntarily perfift in the deter- 
mined train. So at my approach to a houfe which I have but 
once vifited, and that at the diftance of many months, I will to 
recoiled the names of the numerous family I exped to fee there, 
and I do recoiled them. 
On this voluntaiy recolledion of ideas our faculty of reafon 
depends, as it enables us to acquire an idea of the difnmilitude 
of any two ideas. Thus if you voluntarily produce the idea of 
a right-angled triangle, and then of a fquare ; and after having 
excited 32 
VOLUNTARY MOTIONS. 
Sect. IX 2. r- 
excited thefe ideas repeatedly, you excite the idea of their differ- 
ence, which is that of another right-angled triangle inverted 
over the former; you are faid to reafon upon this fubjedl, or 
to compare your ideas. 
Thefe ideas of recollection, like the mufcular motions above 
mentioned, were originally excited by the irritation of external 
bodies, and were termed ideas of perception : afterwards the 
pleafure or pain., that accompanied thefe motions, induced a rep- 
etition of then, in the abfence of the external body, by which 
they were fir ft excited; and then they were termed ideas of 
imagination. At length they become voluntarily pradtifed in 
fucceflicn or in combination for the common purpofes of life ; as 
when we make ourfelvcs mailers of the hillory of mankind, or of 
the fciences they have inveftigated ; and are then called ideas of 
recollection ; and are performed with ftrength and velocity in 
proportion to the energy of the volition that excites them, and 
the quantity of fenforial power. 
II. i. The mufcular motions above defcribed, that are moll 
frequently obedient to the will, are nevcrthelefs occafionally 
caufable by painful or pleafurable fenfation, as in the darting 
from fear, and the contraction of the calf of the leg in the 
cramp. 
2. In like manner the fenfual motions, or ideas, that are moil 
frequently connected with volition, are nevcrthelefs occafionally 
caufable by painful oY pleafurable fenfation. As the hiftories of 
men, or the defcription of places, which we have voluntarily 
taken pains to remember, fometimes occur to us in our 
dreams. 
III. i. The mufcular motions that are generally fubfervient 
to volition, are alfo occafionally caufable by irritation, as in 
ftretching the limbs after fleep, and yawning. In this manner 
a contraCiion of the arm is produced by palling the eledlric fluid 
from the Leyden phial along its mufclcs ; and that even though 
the limb is paralytic. The fudden motion of the arm produces 
a difagreeabie fenfation in the joint, but the mufcles feem to be 
brought into action fimply by irritation. 
2. The ideas, that are generally fubfervient to the will, are 
in like manner occafionally excited by irritation; as when we 
view again an object, we have before well ftudied, and often 
recollected. 
IV. i. Innumerable trains or tribes of motions are afibciatcd 
with thefe voluntary mufcular motions above mentioned ; as 
when I will to extend my arm to a diftant object, fome ether 
mufcles are brought into adlion, and preferve the balance of my 
body. And when I wilh to perform any fleady exertion, as in 
threading Sect. IX. 4. 2. 
VOLUNTARY MOTIONS. 
33 
threading a needle, or chopping with an ax, the pe&oral mufcles 
are at the fame time brought into adlion to preferve the trunk 
of the body motionlefs, and we ceafe to refpire for a time. 
2. In like manner the voluntary fenfual motions, or ideas of 
recolledlion, are affociated with many other trains or tribes of 
ideas. As when I voluntarily recoiled a gothic window, that I 
faw fome time ago, the whole front of the cathedral occurs 
to me at the fame time. 
Vol. I. 
SECT. 34 
ASSOCIATE 
Sect. X. i. i. 
SECT. X. 
OF ASSOCIATE MOTIONS. 
I. I. Many mufcular motions excited by irritations in trains or 
tribes become affociated. 2. And many ideas. II. i. Many 
fenfitive mufcular motions become affociated. 2. And many fen- 
fitive ideas. III. I. Many voluntary mufcular motions become 
affociated. 2. And then become obedient to fenfation or irritation. 
3. And many voluntary ideas become affociated. 
All the fibrous motions, whether mufcular or fenfual, which 
are frequently brought into acSlion together, either in combined 
tribes, or in fucceffive trains, become fo connected by habit, that 
when one of them is reproduced the others have a tendency to 
fucceed or accompany it. 
I. i. Many of our mufcular motions were originally excited 
in fucceffive trains, as the contractions of the auricles and of 
the ventricles of the heart; and others in combined tribes, as 
the various divifions of the mufcles which compofe the calf of 
the leg, which were originally irritated into fynchronous aCtion 
by the tacdium or irkfomenefs of a continued pofture. By fre- 
quent repetitions thefe motions acquire affiociations, which con- 
tinue during our lives, and even after the deftruCtion of the 
grcateft part of the fenforium ; for the heart of a viper or frog 
will continue to pulfate long after it is taken from the body ; 
and when it has entirely ceafed to move, if any part of it is 
goaded with a pin, the whole heart will again renew its pulfa- 
tions. This kind of connexion we ffiall term irritative affiocia- 
tion, to diftinguiffi it from fenfitive and voluntary affiociations. 
2. In like manner many of our ideas are originally excited in 
tribes ; as all the objects of fight, after we become fo well ac- 
quainted with the laws of vifion, as to diftinguiffi figure and dis- 
tance as well as colour; or in trains, as while we pafs along the 
objects that furround us. The tribes thus received by irritation 
become affociated by habit, and have been termed complex ideas 
by the writers of metaphyfics, as this book, or that orange. The 
trains have received no particular name, but thefe are alike af- 
fociations of ideas, and frequently continue during our lives. 
So the tafte of a pine-apple, though we eat it blindfold, recalls 
the colour and ffiape of it; and we can fcarcely think on folidi- 
ty without figure. 
II. i. By the various efforts of our fenfations to acquire or 
avoid their objects, many mufcles are daily brought into iuccef- 
five Sect. X. 2.2. 
MOTIONS. 
35 
five or fynchronous actions ; thefe become aflbciated by habit, 
and are then excited together with great facility, and in many 
inftances gain indiflbluble connexions. So the play of puppies 
and kittens is a reprefentation of their mode of fighting or of 
taking their prey; and the motions of the mufcles neceflary for 
thofe purpofes become aflbciated by habit, and gain a great 
adroitnefs of action by thefe early repetitions; fo the motions 
of the abdominal mufcles, which were originally brought into 
concurrent action with the protrufive motion of the rectum or 
bladder by fenfation, become fo conjoined with them by habit, 
that they not only eafily obey thefe fenfations occafioned by the 
ftimulu's of the excrement and urine, but are brought into vio- 
lent and unreitrainable action in the ftrangury and tenefmus. 
This kind of connexion we (hall term fenfitive aflbciation. 
2. So many of our ideas, that have been excited together or 
in fucceflion by our fenfations, gain fynchronous or fucceflive 
aflbciations, that are fometimes indiflbluble but with life. Hence 
the idea of an inhuman or difhonourable action perpetually calls 
up before us the idea of the wretch that was guilty of it. And 
hence thofe unconquerable antipathies are formed, which fome 
people have to the fight of peculiar kinds of food, of which in 
their infancy they have eaten to excefs or by conftraint. 
III. i. In learn'ng any mechanic art, as mufic, dancing, Or 
the ufe of the fword, we teach many of our mufcles to act to- 
gether or in fucceflion by repeated voluntary efforts ; which by 
habit become formed into tribes or trains of aflbciation, and 
ferve all our purpofes with great facility, and in fome inftances 
acquire an indiflbluble union. Thefe motions are gradually 
formed into a habit of ailing together by a multitude of repeti- 
tions, whilft they are yet feparately caufable by the will, as is 
evident from the long time that is taken up by children in learn- 
ing to walk and to fpeak ; and is experienced by every one, 
when he firft attempts to Ikate upon the ice or to fwim: thefe 
we fhall term voluntary aflbciations. 
2. All thefe mufcular movements, when they are thus afibci- 
ated into tribes or trains, become afterwards not only obedient 
to volition, but to the fenfations and irritations; and the fame 
movement compofes a part of many different tribes or trains of 
motion. Thus a Angle mufcle, when it a£ls in confort with its 
neighbours on one fide, aflifts to move the limb in one direction ; 
and in another, when it a£ts with thofe in its neighbourhood on 
the other fide; and in other directions, when it a£ts feparately 
or jointly with thof® that lie immediately under or above it; and 
all thefe with equal facility after their aflbciations have been 
well eftabliihed. 
The 36 
ASSOCIATE MOTIONS. 
Sect. X. 3. 3, 
The facility, with which each mufcle changes from one aflb- 
ciated tribe to another, and that either backwards or forwards, 
is well obfervable in the mufcles of the arm in moving the wind- 
lafs of an air-pump; and the flownefs of thofe mufcular move- 
ments, that have not been aflbciated by habit, may be experi- 
enced by any one, who (hall attempt to faw the air quick per- 
pendicularly with one hand, and horizontally with the other at 
the fame time. 
3. In learning every kind of fcience we voluntarily aflbciate 
many tribes and trains of ideas, which afterwards are ready for 
all the purpofes either of volition, fenfation, or irritation ; and 
in fome inftances acquire indiflbluble habits of adting together, 
fo as to affedl our reafoning, and influence our actions. Hence 
the neceflity of a good education. 
Thefe aflbciate ideas are gradually formed into habits of act- 
ing together by frequent repetition, while they are yet feparately 
obedient to the will; as is evident from the difficulty we experi- 
ence in gaining fo exabt an idea of the front of St. Paul's church, 
as to be able to delineate it with accuracy, or in recolle&ing a 
poem of a few pages. 
And thefe ideas, thus aflbciated into tribes, not only make up 
the parts of the trains of volition, fenfation, and irritation ; but 
the fame idea compofes a part of many different tribes and trains 
of ideas. So the fimple idea of whitenefs compofes a part of the 
complex idea of fnow, milk, ivory ; and the complex idea of the 
letter A compofes a part of the feveral aflbciated trains of ideas 
that make up the variety of words, into which this letter enters. 
The numerous trains of thefe aflbciated ideas are divided by 
Mr. Hume into three clafles, which lie has termed contiguity, 
caufation, and refemblance. Nor Ihould we wonder to find 
them thus connected together, fince it is the bufinefs of our 
lives to difpofe them into thefe three clafles ; and we become 
valuable to ourfelves and our friends, as we fucceed in it. Thofe 
who have combined an extenfive clafs of ideas by the contiguity 
of time or place, are men learned in the hiftory of mankind, and 
of the fciences they have cultivated. Thofe who have conneft- 
ed a great clafs of ideas of refemblances, poflefs the fource of 
the ornaments of poetry and oratory, and of all rational analo- 
gy. While thofe who have connected great clafles of ideas of 
caufation, are furnifhed with the powers of producing effects. 
Thefe are the men of active wifdom, who lead armies to victory, 
and kingdoms to profperity ; or difeover and improve the fei- 
ences, which meliorate and adorn the condition of humanity. 
SECT. Sect. XI. 1. 
SENSORIAL ACTIONS. 
37 
SECT. XI. 
additional observations on the sensorial powers. 
I. Stimulation is of various kinds, adapted to the organs of fenfe, to 
the mufcles, to hollow membranes, and glands. Some objects irri- 
tate our fenfes by repeated impufes. II. I. Senfation and volition 
frequently ffecl the whole fenforium. 2. Emotions, pafftons, ap- 
petites. 3. Origin of dejlre and averfton. Criterion of volunta- 
ry adlions, difference of brutes and men. 4. Senfbility and vol- 
untarily. III. Affectations formed before nativity, irritative mo- 
■ lions mifaken for affociated ones. 
Irritation. 
I. The various organs of fenfe require various kinds of ftim. 
ulation to excite them into action ; the particles of light pene- 
trate the cornea and humours of the eye, and then irritate the 
naked retina ; fapid particles, diflblved or diffufed in water or 
faliva, and odorous ones, mixed or combined with the air, irri- 
tate the extremities of the nerves of tafte and fmell ; which ei- 
ther penetrate, or are expanded on the membranes of the tongue 
and noftrils ; the auditory nerves are ftimulated by the vibra- 
tions of the atmofphere communicated by means of the tympa- 
num and of the fluid, whether of air or of water, behind it; and 
the nerves of touch by the hardnefs of furrounding bodies, 
though the cuticle is interpofed between thefe bodies and the 
medulla of the nerve. 
As the nerves of the fenfes have each their appropriated ob- 
jects, which ftimulate them into activity ; fo the mufcular 
fibres, which are the terminations of other fets of nerves, have 
their peculiar objects, which excite them into action ; the lon- 
gitudinal mufcles are ftimulated into contraction by extenfion, 
whence the ftretching or pandiculation after a long continued 
pofture, during which they have been kept in a ftate of exten- 
fion ; and the hollow mufcles are excited into aCtion by diften- 
tion, as thofe of the rectum and bladder are induced to protrude 
their contents from their fenfe of the diftention rather than of 
the acrimony of thofe contents. 
There are other objects adapted to ftimulate the nerves, 
which terminate in variety of membranes, and thofe efpecially 
which form the terminations of canals ; thus the preparations 
of mercury particularly affect the falivary glands, ipecacuanha 
the ftomach, aloe the fphinCter of the anus, cantharides that of 
the 38 
SENSORIAL 
Sect. XI. 2. 1. 
the bladder, and laftly every gland of the body appears to be in- 
dued with a kind of tafte, by which it feleds or forms each its 
peculiar fluid from the blood ; and by which it is irritated into 
aCtivity. 
Many of thefe external properties of bodies, which ftimulate 
our organs of fenfe, do not feem to effeCl this by a Angle im- 
pulfe, but by repeated impulfes ; as the nerve of the ear is prob- 
ably not excitable by a Angle vibration of air, nor the optic 
nerve by a Angle particle of light ; which circumftance produ- 
ces fome analogy between thofe two fenfes, at the fame time 
the folidity of bodies is perceived by a Angle application of a 
folid body to the nerves of touch, and that even through the cu- 
ticle ; and we are probably polI'cAcd of a peculiar fenfe to diftin- 
guifh the nice degrees of heat and cold. 
The fenfes of touch and of hearing acquaint us with the me- 
chanical impact and vibration of bodies, thofe of fmcll and tafte 
feem to acquaint us with fome of their chemical properties, 
while the fenfes of viAon and of heat acquaint us with the ex- 
iftence of their peculiar fluids. 
Senfation and Volition. 
II. Many motions are produced by pleafure or pain, and that 
even in contradiction to the power of volition, as in laughing, 
or in the itrangury ; but as no name has been given to pleafure 
or pain, at the time it is exerted fo as to caufe fibrous motions, 
we have ufed the term fenfation for this purpofe ; and mean it 
to bear the fame analogy to pleafure and pain, that the word vo- 
lition does to defire and averfion. 
I. It was mentioned in the fifth Sedion, that, what we have 
termed fenfation is a motion of the central parts, or of the whole 
fenforium, beginning at fome of the extremities of it. This ap- 
pears firft, becaufe our pains and pleafures are always caufed by 
ourideas ormufcularmotions,whicharethemotionsof the extrem- 
ities of the fenforium. And, fecondly, becaufe the fenfation of 
pleafure or pain frequently continues fome time after the ideas 
or mufcular motions which excited it have ceafed : for we often 
feel a glow of pleafure from an agreeable reverie, for many min- 
utes after the ideas, that were the fubjeCt of it, have efcaped 
our memory ; and frequently experience a dejeCtion of fpirits 
without being able to aflign the caufe of it but by much recol- 
lection. 
When the fenforial faculty of defire or averfion is excited fo 
as to caufe fibrous motions, it is termed volition ; which is faid 
in SeCt. V. to be a motion of the central parts, or of the whole 
fenforium. Sect. XI. 2. 2. 
ACTIONS. 
39 
fenforium, terminating in fome of the extremities of it. This 
appears, firft, becaufe our defires and averfions always terminate 
in recolle&ing and comparing our ideas, or in exerting our muf- 
cles ; which are the motions of the extremities of the fenforium* 
And, fecondly, becaufe defire or averfion begins, and frequently 
continues for a time in the central parts of the fenforium, be- 
fore it is peculiarly exerted at the extremities of it ; for we 
fometimes feel deiire or averfion without immediately knowing 
their objects, and in confequence without immediately exerting 
any of our mufcular or fenfual motions to attain them : as in the 
beginning of the paflion of love, and perhaps of hunger, or in 
the ennui of indolent people. 
Though fenfation and volition begin or terminate at the ex- 
tremities or central parts of the fenforium, yet the whole of it 
is frequently influenced by the exertion of thefe faculties, as ap- 
pears from their effects on the external habit : for the whole 
ikin is reddened by fhame, and an univcrfal trembling is pro- 
duced by fear : and every mufcle of the body is agitated in an- 
gry people by the defire of revenge. 
There is another very curious circumftance, which (hews that 
fenfation and volition are movements of the fenforium in con- 
trary directions ; that is, that volition begins at the central parts 
of it, and proceeds to the extremities ; and that fenfation begins 
at the extremities, and proceeds to the central parts : I mean 
that thefe two fenforial faculties cannot be ftrongly exerted at 
the fame time ; for when we exert our volition ftrongly, we do 
not attend to pleafure or pain ; and converfely, when we are 
ftrongly affected with the fenfation of pleafure or pain, we ufe 
no volition. As will be further explained in Se&ion XVIII. 
on fleep, and Section XXXIV. on volition. 
2. All our emotions and paffions feem to arife out of the ex- 
ertions of thefe two faculties of the animal fenforium. Pride, 
hope, joy, are the names of particular pleafures: fhame, defpair, 
forrow, are the names of peculiar pains : and love, ambition, 
avarice, of particular defires : hatred, difguft, fear, anxiety, of 
particular averfions. Whilft the paflion of anger includes the 
pain from a recent injury, and the averfion to the adverfary that 
occafioned it. And compaflion is the pain we experience at 
the fight of mifery, and the deiire of relieving it. 
There is another tribe of defires, which are commonly term- 
ed appetites, and are the immediate confequences of the abfence 
of fome irritative motions. Thofe, which arife from defect of 
internal irritations, have proper names conferred upon them, as 
hunger, thirft, luft, and the defire of air, when our refpiration is 
impaired by noxious vapours ; and of warmth, when we are 
expofed 40 
SENSORIAL 
Sect. XI. 2. j. 
cxpofed to too great a degree of cold. But thofe, whofe Rimu- 
li are external to the body, are named from the objects, which 
are by nature conRituted to excite them ; thcfe defires originate 
from our paR experience of the pleafurable fenfations they oc- 
cafion, as the fmell of a hyacinth, or the tafte of a pine-apple. 
Whence it appears, that our pleafures and pains are at leaft 
as various and as numerous as our irritations ; and that our de- 
fires and averfions muR be as numerous as our pleafures and 
pains. And that as fenfation is here ufed as a general term for 
our numerous pleafures and pains, when they produce the con- 
traftions of our fibres ; fo volition is the general name for our 
defires and averfions, when they produce fibrous contractions. 
Thus when a motion of the central parts, or of the whole fenfo- 
rium, terminates in the exertion of our mufcles, it is generally 
called voluntary action ; when it terminates in the exertion of 
our ideas, it is termed recollection, reafoning, determining. 
3. As the fenfations of pleafure and pain are originally in- 
troduced by the irritations of external objects : fo our defires 
and averfions are originally introduced by thofe fenfations ; for 
when the objects of our pleafures or pains are at a diRance, 
and we cannot inftantaneoufly poflefs the one, or avoid the oth- 
er, then defire or averfion is produced, and a voluntary exertion 
of our ideas or mufcles fucceeds. 
The pain of hunger excites you to look out for food, the tree, 
that Ihades you, prefents its odoriferous fruit before your eyes, 
you approach, pluck, and eat. 
The various movements of walking to the ^ree, gathering the 
fruit, and mafticating it, are afibciated motions introduced by 
their connexion with fenfation ; but if from the uncommon 
height of the tree, the fruit be inacceffible, and you are prevent- 
ed from quickly poflefling the intended pleafure, defire is produ- 
ced. The confequence of this defire is, firR, a deliberation a- 
bout the means to gain the object of pleafure in procefs of time, 
as it cannot be procured immediately ; and, fecondly, the muf- 
cular action necefl'ary for thispurpofe. 
You voluntarily call up all your ideas of cautation, that are 
related to the effebt you defire, and voluntarily examine and 
compare them, and at length determine whether to afeend the 
tree, or to gather Rones from the neighbouring brook, is eafier 
to praCtife, or more promifing of fuccefs ; and, finally, you 
gather the Rones, and repeatedly fling them to diflodge rhe fruit. 
Hence then we gain a criterion to diRinguifh voluntary aCts 
or thoughts from thofe caufed by fenfation. As the former are 
always employed about the means to acquire pleafurable objects, 
or the means to avoid painful ones ; while the latter are em- 
ployed Sect. XL 2. 4. 
ACTIONS. 
41 
ployed in the poflefiion of thofe, which are already in our 
power. 
Hence the activity of this power of volition produces the 
great difference between the human and the brute creation. 
The ideas and the actions of brutes are almoft perpetually em- 
ployed about their prefent pleasures, or their prefent pains ; and, 
except in the few inftances which are mentioned in Seflion 
XVI. on inftinct, they feldom bufy themfelves about the means 
of procuring future blifs, or of avoiding future mifery ; fo that 
the acquiring of languages, the making of tools, and labouring 
for money, which are all only the means to procure pleafures ; 
and the praying to the Deity, as another means to procure hap- 
pinefs, are charafteriftic of human nature. 
4. As there are many difeafes produced by the quantity of 
the fenfation of pain or pleafure being too great or too little ; fo 
are there difeafes produced by the fufceptibility of the conftitu- 
tion to motions caufableby thefe fenfations being too dull or too 
vivid. This fufceptibility of the fyftem to fenfitive motions is 
termed fenfibility, to diftinguifh it from fenfation, which is the 
actual exiftencc or exertion of pain or pleafure. 
Other clafles of difeafes are owing to the cxceffive prompti- 
tude, or fluggifhnefs of the conftitution to voluntary exertions, 
as well as to the quantity of defire or of averfion. This fuf- 
ceptibility of the fyftem to voluntary motions is termed volun- 
tarily, to diftinguifh it from volition, which is the exertion of 
defire or averfion ; thefe difeafes will be treated of at length in 
the progrefs of the work. 
Ajjociation. 
III. i. It is not eafy to afllgn a caufe, why thofe animal move- 
ments, that have once occurred in fucceffion, or in combination, 
fhould afterwards have a tendency to fucceed or accompany 
each other. It is a property of animation, and diftinguilhes this 
order of being from the other productions of nature. 
When a child firfl wrote the word man, it was diftinguifhed 
in his mind into three letters, and thofe letters into many parts 
of letters ; but by repeated ufe the word man becomes to his 
hand in writing it, as to his organs of fpeech in pronouncing it, 
but one movement without any deliberation, or fenfation, or ir- 
ritation, interpofed between the parts of it. And as many fep- 
arate motions of our mufcles thus become united, and form, as 
it were, one motion ; fo each feparate motion before fuch union 
may be conceived to confift of many parts or fpaces moved 
through ; and perhaps even the individual fibres of our mufcles 
Vol. I. G have 42 
SENSORIAL ACTIONS. 
Sect. XL 3. 2. 
have thus gradually been brought to aft in concert, which hab- 
its began to be acquired as early as the very formation of the 
moving organs, long before the nativity of the aijimal ; as ex- 
plained in the SecStion XVI. 2. on inftinCt. 
2. There are many motions of the body, belonging to the ir- 
ritative clafs, which might by a hally obferver be miftaken for 
aflbciated ones; as the periftaltic motion of the ftomach and in- 
teftines, and the contraCtions of the heart and arteries, might be 
fuppofed to be aflbciated with the irritative motions of their 
nerves of fenfe, rather than to be excited by the irritation of 
their mufcular fibres by the diftention, acrimony, or momentum 
of the blood. So the diftention or elongation of mufcles by ob- 
jects external to them irritates them into contraction, though 
the cuticle or other parts may intervene between the ftimulating 
body and the contracting mufcle. Thus a horfe voids his ex- 
crement when its weight or bulk irritates the reClum or fphinc- 
ter ani. Thefe mufcles aCt from the irritation of diftention, 
when he excludes his excrement, but the mufcles of the abdo- 
men and diaphragm are brought into motion by aflbciation with 
thofe of the fphinCter and reClum. 
SECT. Sect. XIL 
OF STIMULUS, &c. 
43 
S E C T. XII. 
OF STIMULUS, SENSORIAL EXERTION, AND FIBROUS CONTRAC- 
TION. 
I. Of fibrous contraflion. i. Two particles of a fibre cannot 
approach without the intervention of fo mething, as in magnetifm, 
eled ricity, elaflicity. Spirit of life is not electric ether. Galvani's 
experiments. 2. Contraction of a fibre. 3. Relaxation fuc- 
ceeds. 4. Succejfive contradions, with intervals, ^tick pulfe 
from debility, from paucity of blood. IV°ak contractions perform- 
ed in lefs time, and with Jhorter intervals. 5. Lafi filia- 
tion of the fibres continues after contraction. 6. Contraction 
greater than ufual induces pleafure or pain. q. Mobility of the 
fibres uniform. Quantity offenfiorial power fluduates. Confli- 
tutes excitability. II. Of ienforial exertion. 1. Animal motion 
includes fiimulus, fenfiorial power, and contractilefibres. The fen- 
forialfaculties adfeparately or conjointly. Stimulus of four kinds. 
Strength and weaknefs defined. Senforial power perpetually ex- 
baufled and renewed. Weaknefs from defied ofifltmulus. From 
defied ofi fenfiorial power, the dired and indired debility ofi Dr. 
Brown. Why we become warm in Buxton bath after a time, and 
fee well after a time in a darkijh room. Fibres may ad violently, 
er with their whole force, and yet feebly. Great exertion in in- 
flammation explained. Great mufcular force of fame infane peo- 
ple. 2. Occajional accumulation offenfiorial power in mufcles fub- 
jed to conflantfiimulus. In animals Jleeping in winter. In eggs, 
feeds, feirrhous tumours, tendons, bones. 3. Great exertion in- 
troduces pleafure or pain. Inflammation. Libration of the fyf- 
tem between torpor and adivity. Fever-fits. 4. Dejire and a- 
verfion introduced. Excefis of volition cures fevers. III. Of re- 
peated ftimulus. I. A fiimulus repeated too frequently lofes ef- 
fid. As opium, wine, grief. Hence old age. Opium and aloes 
in fmalldofes. 2. A fiimulus not repeated too frequently does not 
lofe efed. Perpetual movement ofithe vital organs. 3. A fiim- 
ulus repeated at uniform times produces greater efed. Irrita- 
tion combined with ajfociation. 4. A fiimulus repeated frequent- 
ly and uniformly may be withdrawn, and the adion of the organ 
will continue. Hence the bark cures agues, and firengthens weak 
confutations. 5. Defied ofifiimulus repeated at certain intervals 
caafies fiever-fits. 6 Stimulus long applied ceafes to ad a fecond 
time. q. If a fiimulus excites fenfation in an organ not ufually 
excited into fenfiation, inflammation is produced. IV. Of ftimu- 
lus greater than natural. 1. A fiimulus greater than natural 
diminifhts 44 
OF STIMULUS 
Sect. XII. 1. 1. 
diminifhes the quantity of fenforial power in general. 2. In par- 
ticular organs. 3. Induces the organ into fpafmodic actions. 4. 
Induces the antagoniffibres into adion. 5. Induces the organ in- 
to convulfive or fixedfpafms. 6. Produces p ar alfis of the or- 
gan. V. Of fiimulus lefs than natural. I. Stimulus Ifs than 
■natural occafions accumulation of fenforial power in general. 2. 
In particular organs ,fiujhing of the face in a frojly morning. ' In 
fibres fubjeCt to perpetual fiimulus only. Quantity of fenforial 
power inverfely as the fiimulus. 3. Induces pain. As of cold, 
hunger, head-ach. 4. Induces more feeble and frequent contrac- 
tion. As in low fevers. Which are frequently owing to deficien- 
cy offenforial power rather than to deficiency of fiimulus. 5. In- 
verts fucceffive trains of motion. Inverts ideas. 6. Induces pa- 
ralyfis and death. VI. Cure of increafed exertion. 1. Nat- 
ural cure of exhaufiion of fenforial power. 2. Decreafe the irri- 
tations. Venefedion. Cold. Abfiinence. 3. Prevent the pre- 
vious cold fit. Opium. Bark. Warmth. Anger. Surprife. 
4. Excite fame other part of the fyfiem. Opium and warm bath 
relieve pains both from defied and from excefs of fiimulus. 5. 
Firfi increafe thefiimulus above, and then decreafe it beneath the 
natural quantity. VII. Cure of decreafed exertion. 1. Nat- 
ural cure by accumulation of fenforialpower. Ague-fits. Synco- 
pe. 2- Increafe thefiimulation, by wine, opium, given fo as not to 
intoxicate. Cheerful ideas. 3. Change the kinds of fiimulus. 
4. Stimulate the officiated organs. Blifiers of ufe in heart-burn, 
and cold extremities. 5. Decreafe the fiimulation for a time, cold 
bath. 6. Decreafe the fiimulation below natural, and then. in- 
creafe it above natural. Bark after emetics. Opium after vene- 
fedion. Pradice of Sydenham in chlorofis. q. Prevent unneeef- 
fary expenditure of fenforial power. Decumbent pojlure,ftlence, 
darknefs. Pulfe quickened by rift ng out of bed. 8. To the great- 
ef degree of quiefcence apply the leafi fiimulus. Otherwife pa- 
ralyfis or inflammation of the organ enfues. Gin, wine, blifiers, 
defray by too great fiimulation in fevers with debility. Intoxica- 
tion in the jlightefi degree fucceeded by debility. Golden rule for 
determining the befit degree of fiimulus in low fevers. Another 
golden rule for determining the quantity offpirit which thofe, who 
are debilitated by drinking it, may fafely omit. VIII. Conclufwn. 
Somefiimuli increafe the produdion of fenforial power. 
I. Of fibrous contraction. 
i. If two particles of iron lie near each other without mo- 
tion, and afterwards approach each other; it is reafonable to 
conclude that fomcthing behdes the iron particles is the caufe of 
their Sect. XII. 1. 1. 
AND EXERTION. 
45 
their approximation ; this invifible fomething is termed magnet- 
ifm. In the fame manner, if the particles, which compo e an 
animal mufcle, do not touch each other in the relaxed Rate of 
the mufcle, and are brought into contact during the contraflion 
of the mufcle; it is reafonable to conclude, that fome other 
agent is the caufe of this new approximation. For nothing san 
act^ ivhere it does not exif; for to ahi includes to exif; and there- 
fore the particles of the mufcular fibre (which in its Rate of re- 
laxation are fuppofed not to touch) cannot affeft each other 
without the influence of fome intermediate agent; this agent is 
here termed the fpirit of animation, or fenforial power, but may 
with equal propriety be termed the power, which caufes con- 
traflion ; or may be called by any other name, which the reader 
may choofe to affix to it. 
The contjaflion of a mufcular fibre may be compared to the 
following eleftric experiment, which is here mentioned not as 
a philofophical analogy, but as an illuftration or fim:;e4 to lac - 
itate the conception of a difficult fubjeft. Let twenty vc. y fm 1 
Leyden phials properly coated be hung in a row by fine filk 
threads at a fmall dillance from each other ; let the internal 
charge of one phial be pofitive, and of the other negative alter- 
nately, if a communication be made from the internal furface of 
the firft to the external furface of the laft in the row, they will 
all of them inftantly approach each other, and thus Ihorten a line 
that might connefl them like a mufcular fibre. See Botanic 
Garden, P. I. Canto I. 1. 202. note on Gymnotus. 
The attraflions of eleflricity or of magnetifm do not apply 
philofophically to the illuftration of the contraflion of animal 
iibres, fince the force of thofe attraflions incrcafes in fome pro- 
portion inverfely as the diftance, but in mufcular motion there 
appears no difference in velocity or ftrength during the begin- 
ning or end of the contraction, but what may be clearly afcribed 
to the varying mechanic advantage in the approximation of one 
bone to another. Nor can mufcular motion be affimilated with 
greater plaufibility to the attradlion of cohefion or elafticity ; for 
in bending a fteel fpring, as a fmall fword, a lefs force is re- 
quired to bend it the firft inch than the fecond; and the fecond 
than the third ; the particles of lleel on the convex fide of the 
bent fpring endeavouring to reltore themfelvcs more powerfully 
the further they are drawn from each other. Sec Botanic Gar- 
den, P. I. addit. Note XVIII. 
I am aware that this may be explained another way, by fup- 
pofing the elafticity of the fpring to depend more on the com- 
preffion of the particles on the concave fide than on the exten- 
fion of them on the convex fide; and by fuppofing the elafticity 
of 46 
Of STIMULUS 
Sect. XII. 1. 2* 
•f the elaftic gum to depend more on the refiftance to the lateral 
comprefiion of its particles than to the longitudinal extenfion of 
them. Neverthelefs in mufcular contraction, as above obferv- 
ed, there appears no difference in the velocity or force of it at 
its commencement or at its termination ; from whence we mult 
conclude that animal contraCiion is governed by laws of its own, 
and not by thofc of mechanics, chemiftry, magnetifm, or elec- 
tricity. 
On thefe accounts I do not think the experiments conclufive, 
which were lately publilhed by Galvani, Volta, and others, to 
fhew a fimilitude between the fpirit of animation, which con- 
tracts the mufcular fibres, and the eleCtric fluid. Since the 
cleCtric fluid may aCt only as a more potent ftimulus exciting 
the mufcular fibres into aftion, and not by fupplying them with 
a new quantity of the fpirit of life. Thus in a recent hemiple- 
gia I have frequently obferved, when the patient yawned and 
ftretched himfelf, that the paralytic limbs moved alfo, though 
they were totally difobedient to the will. And when he was 
eledrified by palling fhocks from the affeCted hand to the affeft- 
ed foot, a motion of the paralytic limbs was alfo produced. Now 
as in the aft of yawning the mufcles of the paralytic limbs were 
excited into aftion by the ftimulus of the irkfomenefs of a con- 
tinued poflure, and not by any additional quantity of the fpirit 
of life ; fo we may conclude, that the paflage of the eleftric flu- 
id, which produced a fimilar effeft, afted only as a ftimulus, 
and net by fupplying any addition of fenforial power. 
If neverthelefs this theory fhould ever become eftablilhed, a 
ftimulus muft be called an eduftor of vital ether ; which ftim- 
ulus may confift of fenfation or volition, as in the eleftric eel, as 
well as in the appulfes of external bodies; and by drawing off 
the charges of vital fluid may occaflon the contraftion or mo- 
tions of the mufcular fibres, and organs of fenfe. 
2. The immediate effeft of the aftion of the fpirit of anima- 
tion or fenforial power on the fibrous parts of the body, whether 
it afts in the mode of irritation, fenfation, volition, or aflbeia- 
tion, is a contraftion of the animal fibre, according to the fec- 
ond law of animal caufation. Seft. IV. Thus the ftimulus of 
the blood induces the contraftion of the heart; the agreeable 
tafte of a ftrawberry produces the contraftion of the mufcles of 
deglutition ; the effort of the will contrafts the mufcles, which 
move the limbs in walking ; and by affbeiation other mufcles of 
the trunk arc brought into contraftion to preferve the balance 
of the body. The fibrous extremities of the organs of fenfe 
have been (hewn, by the ocular fpeftra in Seft III. to fuffer 
fimilar Sect. XII. 1. 3. 
AND EXERTION. 
47 
fimilar contraction by each of the above modes of excitation ; 
and by their configurations to conftitute our ideas. 
3. After animal fibres have for fome time been excited into 
contraCiion, a relaxation fucceeds, even though the exciting 
caufe continues to aCt. In refpeCt to the irritative motions this 
is exemplified in the periftaltic contraCtions of the bowels ; 
which ceafe and are renewed alternately, though the ftimulus of 
the aliment continues to be uniformly applied ; in the fenfitive 
motions, as in ftrangury, tenefmus, and parturition, the alter- 
nate contraCtions and relaxations of the mufcles exift, though 
the ftimulus is perpetual. In our voluntary exertions it is expe- 
rienced, as no one can hang long by the hands, however vehe- 
mently he wills fo to do; and in the affociate motions the con- 
ftant change of our attitudes evinces the neceflity of relaxation 
to thofe mufcles, which have been long in aCtion. 
This relaxation of a mufcle after its contraCiion, even though 
the ftimulus continues to be applied, appears to arife from the 
expenditure or diminution of the fpirit of animation previoufly 
refident in the mufcle, according to the fecond law of animal 
caufation in SeCt. IV. In thofe conftitutions, which are termed 
weak, the fpirit of animation becomes fooner exhaufted, and 
tremulous motions are produced, as in the hands of infirm peo- 
ple, when they lift a cup to their mouths. This quicker ex- 
hauftion of the fpirit of animation is probably owing to a lefs 
quantity of it refiding in the aCling fibres, which therefore more 
frequently require a fupply from the nerves, which belong to 
them. 
4. If the fenforial power continues to aCt, whether it aCts in 
the mode of irritation, fenfation, volition, or aflbeiation, a new 
contraCiion of the animal fibre fucceeds after a certain interval; 
which interval is of fhorter continuance in weak people than in 
ftrong ones. This is exemplified in the fhaking of the hands of 
weak people, when they attempt to write. In a manufeript epif- 
tle of one of my correfpondents, which is written in a fmall 
hand, I obferved from four to fix zigzags in the perpendicular 
ftroke of every letter, which fhews that both the contraCiions of 
the fingers, and intervals between them, muft have been per- 
formed in very fhort periods of time. 
The times of contraction of the mufcles of enfeebled people 
being lefs, and the intervals between thofe contraCtions being 
lefs alfo, accounts for the quick pulfe in fevers with debility, 
and in dying animals. The fhortnefs of the intervals between 
one contraCtion and another in weak conftitutions, is probably 
owing to the general deficiency of the quantity of the fpirit of 
animation, and that therefore there is a lefs quantity cf it to be 
received 48 
OF STIMULUS 
Sect. XII. r. 4, 
received at each interval of the adivity of the fibres. Hence in 
repeated motions, as of the fingers in performing on the harpfi- 
chord, it would at firft fight appear, that fwiftnefs and ftrength 
were incompatible ; neverthelefs the fingle contraction of a muf- 
cle is performed with greater velocity as well as with greater 
force by vigorous conftitutions, as in throwing a javelin. 
There is however another circumftance, which may often 
contribute to caufe the quicknefs of the pulfe in nervous fevers, 
as in animals bleeding to death in the flaughter-houfe j which is 
the deficient quantity of blood ; whence the heart is but half 
diftended, and in confequence fooner contrails. See Sect. 
XXXII. 2. i. 
For we muft not confound frequency of repetition with 
quicknefs of motion, or the number of pulfations with the ve- 
locity, with which the fibres, which conftitute the coats of the 
arteries, contract themfelves. For where the frequency of the 
pulfations is but feventy-five in a minute, as in health ; the con- 
tracting fibres, which conftitute the fidcs of the arteries, may 
move through a greater fpace in a given time, than where the 
frequency of pulfation is one hundred and fifty in a minute, as 
in fame fevers with great debility. For if in thofe fevers the 
arteries do not expand themfelves in their diaftole to more than 
half the ufual diameter of their diaftole in health, the fibres 
which conftitute their coats, will move through a lefs fpace in 
a minute than in health, though they make two pulfations for 
one. 
Suppcfe the diameter of the artery during its fyftole to be 
one line, and that the diameter of the fame artery during its di- 
aftolc is in health four lines, and in a fever with great debility 
only two lines. It follows that the arterial fibres contract in 
health from a circle of twelve lines in circumference to a circle 
of three lines in circumference, that is they move through a fpace 
of nine lines in length. While the arterial fibres in the fever 
with debility would twice contraCi from a circle of fix lines to a 
circle of three lines ; that is while they move through a fpace 
equal to fix lines. Hence though the frequency of pulfation 
in fever be greater as two to one, yet the velocity of contrac- 
tion in health is greater as nine to fix, or as three to two. 
On the contrary in inflammatory difeafes with ftrength, as in 
the pleurify, the velocity of the contracting fides of the arteries 
is much greater than in health : for if we fuppofe the number of 
pulfations in a pleurify to be half as much more than in health, 
that is as one hundred and twenty to eighty, (which is about 
what generally happens in inflammatory difeafes) and if the di- 
ameter of the artery in diaftole be one third greater than in 
health. Sect. XII. 1. 5. 
AND EXERTION. 
49 
health, which I believe is near the truth, the refult will be, that 
the velocity of the contractile Iides of the arteries will be in a 
pleurify as two and a half to one, compared to the velocity of 
their contraCtion in a flate of health; for if the circumference 
of the fyftole of the artery be three lines, and the diaftole in 
health be twelve lines in circumference, and in a pleurify 
eighteen lines ; and fecondly, if the artery pulfates thrice in the 
difeafed flate for twice in the healthy one, it follows, that the 
velocity of contraCtion in the difeafed Hate to that in the healthy 
ftate will be forty-five to eighteen, or as two and a half to one. 
From hence it would appear, that if we had a criterion to de- 
termine the velocity of the arterial contraCiions, it would at the 
fame time give us their ftrength, and thus be of more fervice in 
diftinguilhing difeafes, than the knowledge of their frequency. 
As fuch a criterion cannot be had, the frequency of pulfation, 
the age of the patient being allowed for, will in fome meafure 
afhft us to diftinguifh arterial ftrength from arterial debility, 
fince in inflammatory difeafes with ftrength the frequency fel- 
dom exceeds one hundred and eighteen or one hundred and 
twenty pulfations in a minute ; unlefs under fome peculiar cir- 
cumftance, as the great additional ftimuli of wine or of exter- 
nal heat. 
5. After a mufcle or organ of fenfe has been excited into 
contraCtion, and the fenforial power ceafes to aCt, the laft fitua- 
tion or configuration of it continues ; unlefs it be difturbed by 
the aClion of fome antagonift fibres, or other extraneous power. 
Thus in weak or languid people, wherever they throw their 
limbs on their bed or fofa, there they lie, till another exertion 
changes their attitude ; hence one kind of ocular fpeCtra feems 
to be produced after looking at bright objeCts; thus when a 
fire-ftick is whirled round in the night, there appears in the eye 
a complete circle of fire ; the aClion or configuration of one 
part of the retina not ceafing before the return of the whirling 
fire. 
Thus if any one looks at the fetting fun for a fhort time, and 
then covers his clofed eyes with his hand, he will for many fec- 
onds of time perceive the image of the fun on his retina. A 
fimilar image of all other bodies would remain fome time in the 
eye, but is effaced by the eternal change of the motions of the 
extremity of this nerve in our attention to other objeCts. See 
SeCl. XVII. 1. 3. on Sleep. Hence the dark fpots, and other 
ocular fpeCtra, are more frequently attended to, and remain 
longer in the eyes of weak people, as after violent exercife, in- 
toxication, or want of fleep. 
6. A contraction of the fibres fomewhat greater than ufual 
Vol. I. H introduces 50 
OF STIMULUS 
Sect. XII. i. 7. 
introduces pleafurable fenfation into the fyRem, according to the 
fourth law of animal caufation. Hence the pleafure in the be- 
ginning of drunkennefs is owing to the increafed aCtion of the 
fyRem from the Rim ulus of vinous fpirit or of opium. If the 
contractions be Rill greater in energy or duration, painful fen- 
fations are introduced, as in confequence of great heat, or cauf- 
tic applications, or fatigue. 
If any part of the fyRem, which is ufed to perpetual activity, 
as the Romach, or heart, or the fine veflels of the fkin, ads for a 
time with lefs energy, another kind of painful fenfation enfues, 
which is called hunger, or faintnefs, or cold. This occurs in a 
lefs degree in the locomotive mufcles, and is called wearifome- 
nefs. In the two former kinds of fenfation there is an expendi- 
ture of fenforial power, in thefe latter there is an accumulation 
of it. 
7. We have ufed the words exertion of fenforial power as a 
general term to exprefs either irritation, fenfation, volition, or 
afleciation; that is, to exprefs the aCtivity or motion of the fpirit 
of animation, at the thne it produces the contraCiions of the 
fibrous parts of the fyfiqm. It may be fuppofed that there may 
exiR a greater or lefs mobility of the fibrous parts of our fyRem, 
or a propensity tovbe simulated into contraCiion by the greater 
or lefs priergy of the fpirit of animation ; and that 
hence if the exertion of the fenforial power be in its natural 
Rate, and the mobility of the fibres be increafed, the fame quan- 
tity of fibrous contraCtion will be caufed, as if the mobility of 
the fibres continues in its natural Rate, and the fenforial exertion 
be increafed. 
Thus it may be conceived, that in difeafes accompanied with 
Rrength, as in inflammatory fevers with arterial Rrength, that 
the caufe of greater fibrous contraCiion may exiR in the increaf- 
ed mobility of the fibres, whofe contraCtions are thence both 
more forcible and more frequent. And that in difeafes attended 
with debility, as in nervous fevers, where the fibrous contrac- 
tions are weaker, and more frequent, it may be conceived that 
the caufe confiRs in a decreafc of mobility of the fibres; and 
that thofe weak conRitutions, which are attended with cold 
extremities and large pupils of the eyes, may poflefs lefs mobil- 
ity of the contradile fibres, as well as lefs quantity of exertion 
of the fpirit of animation. 
In anfwer to this mode of reafoning it may be fufficient to ob- 
ferve, that the contraCtile fibres confiR of inert matter, and 
when the fenforial power is withdrawn, as in death, they poflefs 
no power of motion at all, but remain in their laR Rate, whether 
of contraCtion or relaxation, and muR thence derive the whole 
of Sect. XII. 1. 7. 
AND EXERTION. 
51 
of this property from the fpirit of animation. At the fame time 
it is not improbable, that the moving fibres of ftrong people may 
poflefs a capability of receiving or containing a greater quantity 
of the fpirit of animation than thofe of weak people. 
In every contraction of a fibre there is an expenditure of the 
fenforial power, or fpirit of animation ; and where the exertion 
of this fenforial power has been for fome time increafed, and the 
mufcles or organs of fenfe have in confequence aCled with 
greater energy, its propenfity to activity is proportionally leflen- 
ed ; which is to be afcribed to the exhauftion or diminution of 
its quantity. On the contrary, where there has been lefs fibrous 
contraction than ufual for a certain time, the fenforial power or 
fpirit of animation becomes accumulated in the inactive part of 
the fyltem. Hence vigour fucceeds reft, and hence the propen- 
fity to action of all our organs of fenfe and mufcles is in a ftatc 
of perpetual fluctuation. The irritability for inftance of the 
retina, that is, its quantity of fenforial power, varies every mo- 
ment according to the brightnefs or obfcurity of the objcCt laft 
beheld compared with the prefent one. The fame occurs to 
our fenfe of heat, and to every part of our fyftem, which is ca- 
pable of being excited into aCtion. 
When this variation of the exertion of the fenforial power be- 
comes much and permanently above or beneath the natural 
quantity, it becomes a difeafe. If the irritative motions be too 
great or too little, it fhews that the ftimulus of external things 
affeCls this fenforial power too violently or too inertly. If the 
fenfitive motions be too great or too little, the caufe arifes from 
the deficient or exuberant quantity of fenfation produced in 
confequence of the motions of the mufcular fibres or organs of 
fenfe ; if the voluntary actions are difeafed the caufe is to be 
looked for in the quantity of volition produced in confequence 
of the defire or averfion occafioned by the painful or pleafurable 
fenfations above mentioned. And the difeafes of afibciation 
probably depend on the greater or lefs quantity of the other 
three fenforial powers by which they were formed. 
From whence it appears that the propenfity to aCtion, wheth- 
er it be called irritability, fenfibility, voluntarity, or aflbeiability, 
is only another mode of exprelfion for the quantity of fenforial 
power refiding in the organ to be excited. And that on the 
contrary the words inirritability and infenfibility, together with 
inaptitude to voluntary and aiTociate motions, are fynonymous 
with deficiency of the quantity of fenforial power, or of the 
fpirit of animation, refiding in the organs to be excited. 
IL Of 52 
OF STIMULUS 
Sect. XII. 2. 1. 
II. Offenforial Exertion. 
i. There are three circumftances to be attended to in the 
production of animal motions. ift. The ftimulus. 2d. The 
fenforial power. 3d. The contractile fibre, ift. A ftimulus, 
external to the organ, originally induces into aCtion the fenfo- 
rial faculty termed irritation ; this produces the contraCtion of 
the fibres, which, if it be perceived at all, introduces pleafurc or 
pain ; which in their aCtive ftate are termed fenfation; which 
is another fenforial faculty, and occafionally produces contrac- 
tion of the fibres; this pleafure or pain is therefore to be con- 
fidered as another ftimulus, which may either aCt alone or in 
conjunction with the former faculty of the fenforium termed 
irritation. This new ftimulus of pleafure or pain either induces 
into aCtion the fenforial faculty termed fenfation, which then 
produces the contraCtion of the fibres; or it introduces defire 
or averfion, which excite into aCtion another fenforial faculty, 
termed volition, and may therefore be confidered as another 
ftimulus, which either alone or in conjunction with one or both 
of the two former faculties of the fenforium produces the con- 
traCtion of animal fibres. There is another fenforial power, 
that of aflbeiation, which perpetually, in conjunction with one 
or more of the above, and frequently fingly, produces the con- 
traCtion of animal fibres, and which is itfelf excited into aCtion 
by the previous motions of contracting fibres. 
Now as the fenforial power, termed irritation, refiding in any 
particular fibres, is excited into exertion by the ftimulus of ex- 
ternal bodies aCting on thofe fibres; the fenforial power, termed 
fenfation, refiding in any particular fibres is excited into exertion 
by the ftimulus of pleafure or pain aCting on thofe fibres; the 
fenforial power, termed volition, refiding in any particular fibres 
is excited into exertion by the ftimulus of defire or averfion ; 
and the fenforial power, termed aflbeiation, refiding in any par- 
ticular fibres, is excited into aCtion by the ftimulus of other fi- 
brous motions, which had frequently preceded them. The 
word ftimulus may therefore be ufed without impropriety of 
language, for any of thefe four caufes, which excite the four 
fenforial powers into exertion. For though the immediate 
caufe of volition has generally been termed a motive; and that 
of irritation only has generally obtained the name of jlimulus ; 
yet as the immediate caufe, which excites the fenforial powers 
of fenfation, or of aflbeiation, into exertion, have obtained no 
general name, we (hall ufe the word ftimulus for them all. 
Hence the quantity of motion produced in any particular 
part of the animal fyftem will be as the quantity of ftimulus, 
and Sect. XII. 2. 1. 
AND EXERTION. 
53 
and the quantity of fenforial power, or fpirit of animation, re- 
ading in the contracting fibres. Where both thefe quantities 
are great, ftrength is produced, when that word is applied to the 
motions of animal bodies. Whtre either of them is deficient, 
•weaknefs is produced, as applied to the motions of animal bodies. 
Now as the fenforial power, or fpirit of animation, is perpet- 
ually exhauiled by the expenditure of it in fibrous contractions, 
and is perpetually renewed by the fecretion or production of it 
in the brain and fpinal marrow, the quantity of animal ftrength 
mull be in a perpetual ftate of fluctuation on this account; and 
if to this be added the unceafing variation of all the four kinds 
of ftimulus above defcribed, which produce the exertions of the 
fenforial powers, the ceafelefs viciflitude of animal ftrength be- 
comes eafily comprehended. 
If the quantity of fenforial power remains the fame, and the 
quantity of ftimulus be leflened, a weaknefs of the fibrous con- 
traCtions enfues, which may be denominated debility from defeat 
offtimulus. If the quantity of ftimulus remains the fame, and 
the quantity of fenforial power be leflened, another kind of 
weaknefs enfues, which may be termed debility from defect offen- 
forial power ; the former of thefe is called by Dr. Brown, in 
his Elements of Medicine, direCt debility, and the latter indi- 
rect debility. The coincidence of fome parts of this work with 
correfpondent deductions in the Brunonian Elementa Medi- 
cinse, a work (with fome exceptions) of great genius, muft be 
confidered as confirmations of the truth of the theory, as they 
were probably arrived at by different trains of reafoning. 
Thus in thofe who have been expofed to cold and hunger 
there is a deficiency of ftimulus. While in nervous fever there 
is a deficiency of fenforial power. And in habitual drunkards, 
in a morning before their ufual potation, there is a deficiency 
both of ftimulus and of fenforial power. While, on the other 
hand, in the beginning of intoxication there is an excefs of ftim- 
ulus ; in the hot-ach, after the hands have been immerfed in 
fnow there is a redundancy of fenforial power ; and in inflam- 
matory difeafes with arterial ftrength, there is an excefs of both. 
Hence if the fenforial power be leflened, while the quantity 
of ftimulus remains the fame, as in nervous fever, the frequen- 
cy of repetition of the arterial contractions may continue, but 
their force in refpeft to removing obftacles, as in promoting the 
circulation of the blood, or the velocity of each contraction, 
will be diminifhed, that is, the animal ftrength will be leflened. 
And fccondly, if the quantity of fenforial power be leflened, and 
the ftimulus be increafed to a certain degree, as in giving opium 
in 54 
OF STIMULUS 
Sect. XII. 2. i. 
jin nervous fevers, the arterial contractions may be performed 
more frequently than natural, yet with lefs ftrength. 
And thirdly, if the fenforial power continues the fame in re- 
fpect to quantity, and the ftimulus be fomewhat diminifhed, as in 
going into a darkilh room, or into a coldilh bath, fuppofe of a- 
bout eighty degrees of heat, as Buxton-bath, a temporary weak- 
nefs of the affected fibres is induced, till an accumulation of fen- 
forial power gradually fucceeds, and counterbalances the de- 
ficiency of ftimulus, and then the bath ceafes to feel cold, and 
the room ceafes to appear dark ; becaufe the fibres of the fub- 
cutaneous veffels, or of the organs of fenfe, act with their ufu- 
al energy. 
A fet of mufcular fibres may thus be ftimulated into violent 
exertion, that is, they may aft frequently, and with their whole 
fenforial power, but may neverthelefs not act ftrongly ; becaufe 
the quantity of their fenforial power was originally fmall, or 
was previoufly exhaufted. Hence a ftimulus may be great, and 
the irritation in confequence act with its full force, as in the hot 
paroxyfms of nervous fever ; but if the fenforial power, termed 
irritation, be fmall in quantity, the force of the fibrous contrac- 
tions, and the times of their continuance in their contracted 
Rate, will be proportionally fmall. 
In the fame manner in the hot paroxyfm of putrid fevers, 
which are fhewn in Sect. XXXIII. to be inflammatory fevers 
with arterial debility, the fenforial power termed fenfation is ex- 
erted with great activity, yet the fibrous contractions, which 
produce the circulation of the blood, are performed without 
ftrength, becaufe the quantity of fenforial power then refiding 
in that part of the fyftem is fmall. 
Thus in irritative fever with arterial ftrength, that is, with 
excefs of fpirit of animation, the quantity of exertion during 
the hot part of the paroxyfm is to be eftimated from the quan- 
tity of ftimulus, and the quantity of fenforial power, while in 
fenfitive (or inflammatory) fever with arterial ftrength, that is, 
with excefs of fpirit of animation, the violent and forcible ac- 
tions of the vafcular fyftem during the hot part of the paroxyfm 
are induced by the exertions of two fenforial powers, which are 
excited by two kinds of ftimulus. Thefe are the fenforial pow- 
er of irritation excited by the ftimulus of bodies external to the 
moving fibres, and the fenforial power of fenfation excited by 
the pain. in confequence of the increafed contractions of thofe 
moving fibres. 
And in infane people in fome cafes the force of their mufcu- 
lar actions will be in proportion to the quantity of fenforial 
power, which they poftefs, and the quantity of the ftimulus of 
defire Sect. XII. 2. 2. 
AND EXERTION. 
55 
defire or averfion, which excites their volition into action. At 
the fame time in other cafes the ftimulus of pain or pleafure, 
and the ftimulus of external bodies, may excite into aCtion the 
fenforial powers of fenfation and irritation, and thus add great- 
er force to their mufcular aCtions. 
2. The application of the ftimulus, whether that ftimulus be 
fome quality of external bodies, or pleafure or pain, or defire or 
averfion, or a link of aflbeiation, excites the correfpondent fenfo- 
rial power into aCtion, and this caufes the cdntraCtion of the fi- 
bre. On the contraction of the fibre a part of the fpirit of ani- 
mation becomes expended, and the fibre ceafes to contract, 
though the ftimulus continues to be applied ; till in a certain 
time the fibre having received a fupply of fenforial power is 
ready to contraCt again if the ftimulus continues to be applied. 
If the ftimulus on the contrary be withdrawn, the fame quanti- 
ty of quiefeent fenforial power becomes refident in the fibre as 
before its contraCtion ; as appears from the readinefs for aCtion 
of the large locomotive mufcles of the body in a Ihort time af- 
ter common exertion. 
But in thofe mufcular fibres, which are fubjeCt to conftant 
ftimulus, as the arteries, glands, and capillary veflels, another 
phenomenon occurs, if their accuftomed ftimulus be withdrawn ; 
which is, that the fenforial power becomes accumulated in the 
contraCtile fibres, owing to the want of its being perpetually 
expended, or carried away, by their ufual unremitted contrac- 
tions. And on this account thofe mufcular fibres become af- 
terwards excitable into their natural adions by a much weaker 
ftimulus ; or into unnatural violence of aCtion by their accuf- 
tomed ftimulus, as is feen in the hot fits of intermittent fevers, 
which are in confequence of the previous cold ones. Thus the 
minute veffels of the Ikin are conftantly ftimulated by the 
fluid matter of heat; if the quantity of this ftimulus of heat be 
a while diminiflied, as in covering the hands with fnow, the 
veflels ceafe to aCt, as appears from the palenefs of the Ikin ; if 
this cold application of ihow be continued but a fhort time, the 
fenforial power, which had habitually been fupplied to the fi- 
bres, becomes now accumulated in them, owing to the want of 
its being expended by their accuftomed contraCiions. And 
thence a lefs ftimulus of heat will now excite them into violent 
contraCtions. 
If the quiefcence of fibres, which had previoufly been fubjeCt 
to perpetual ftimulus, continues a longer time ; or their accuf- 
tomed ftimulus be more completely withdrawn ; the accumula- 
tion of fenforial power becomes ftill greater, as in thofe expofed 
to cold and hunger ; pain is produced, and the organ gradually 
dies 56 
OF STIMULUS 
Sect. XII. 2. 3. 
dies from the chemical changes, which take place in it ; or it is 
at a great diftance of time reftored to action by ftimulus appli- 
ed with great caution in fmall quantity, as happens to fome 
larger animals and to many infefts, which during the winter 
months lie benumbed with cold, and are faid to fleep, and to 
perfons apparently drowned, or apparently frozen to death. 
Snails have been faid to revive by throwing them into water af- 
ter having been many years Ihut up in the cabinets of the curi- 
ous ; and eggs and feeds in general are reftored to life after 
many months of torpor by the ftimulus of warmth and moifture. 
The inflammation of fchirrous tumours, which have long 
exifted in a ftate of inaction, is a procefs of this kind ; as well 
as the fenfibility acquired by inflamed tendons and bones, which 
had at their formation a fimilar fenfibility, which had fo long 
lain dormant in their uninflamed ftate. 
3. If after long quiefcence from defetfl of ftimulus the fibres, 
which had previoufly been habituated to perpetual ftimulus, are 
again expofed to but their ufual quantity of it ; as in thofe who 
have fuffered the extremes of cold or hunger ; a violent exer- 
tion of the aftedted organ commences, owing, as above explain- 
ed, to the great accumulation of fenforial power. This violent 
exertion not only diminifhes the accumulated fpirit of anima- 
tion, but at the fame time induces pleafure or pain into the fyf- 
tem, which, whether it be fucceeded by inflammation or not, 
becomes an additional ftimulus, and airing along with the for- 
mer one, produces ftill greater exertions ; and thus reduces the 
fenforial power in the contrafling fibres beneath its natural 
quantity. 
When the fpirit of animation is thus exhaufted by ufelefs ex- 
ertions, the organ becomes torpid or unexcitable into aflion, and 
2 fecond fit of quiefcence fucceeds that of abundant activity. 
During this fecond fit of quiefcence the fenforial power be- 
comes again accumulated, and another fit of exertion follows in 
train. Thefe viciffitudes of exertion and inertion of the arterial 
fyftem conftitute the paroxyfms of remittent fevers ; or inter- 
mittent ones, when there is an interval of the natural aflion of 
the arteries between the exacerbations. 
In thefe paroxifms of fevers, which confift of the libration of 
the arterial fyftem between the extremes of exertion and qui- 
efcence, either the fits become lefs and lefs violent from the con- 
trailile fibres becoming lefs excitable to the ftimulus by habit, 
that is, by becoming accuftomed to it, as explained below XII. 
3. 1. or the whole fenforial power becomes exhaufted, and the 
arteries ceafe to beat, and the patient dies in the cold part of 
the paroxifm. Or fecondly, fo much pain is introduced into 
the Sect. XII. 2. 4. 
AND EXERTION. 
57 
the fyftem by the violent contractions of the fibres, that inflam- 
mation arifes, which prevents future cold fits by expending a 
part of the fenforial power in the extenfion of old veflels or the 
production of new ones ; and thus preventing the too great ac- 
cumulation or exertion of it in other parts of the fyftem ; or 
which by the great increafe of ftimulus excites into great aCtion 
the whole glandular fyftem as well as the arterial, and thence a 
greater quarttity of fenforial power is produced in the brain,and 
thus its exhauftion in any peculiar part of the fyftem ceafes to be 
effected. 
4. Or thirdly, in confequence of the painful or pleafurable 
fenfation above mentioned, defire and averfion are introduced, 
and inordinate volition fucceeds ; which by its own exertions 
expends fo much of the fpirit of animation, that the two other 
fenforial faculties, or irritation and fenfation, act fo much more 
feebly ; that the paroxyfms of fever, or that libration between 
the extremes of exertion and inactivity of the arterial fyftem, 
gradually fubfides. On this account a temporary infanity is a 
favourable fign in fevers, as I have had fome opportunities of 
obferving. ' 
III. Of repeated Stimulus. 
I. When a ftimulus is repeated more frequently than the ex- 
penditure of fenforial power can be renewed in the afting or- 
gan, the effect of the ftimulus becomes gradually diminifhed. 
Thus if two grains of opium be fwallowed by a perfon unufed 
to fo ftrong a ftimulus, all the vafcular fyftems in the body act 
with great energy, all the fecretions and the abforption from 
thofe fccreted fluids are increafed in quantity ; and pleafurc or 
.pain are introduced into the fyftem, which adds an additional 
ftimulus to that already too great. After fome hours the fenfo- 
rial power becomes diminifhed in quantity, expended by the 
great activity of the fyftem ; and thence, when the ftimulus of 
the opium is withdrawn, the fibres will not obey their ufual de- 
gree of natural ftimulus, and a confequent torpor or quiefcence 
lucceeds, as is experienced by drunkards, who on the day after 
a great excefs of fpirituous potation feel indigeftion, head-ache, 
and general debility. 
In this fit of torpor or quiefcence of a part or of the whole 
of the fyftem, an accumulation of the fenforial power in the af- 
fected fibres is formed, and occafions a fecond paroxyfm of ex- 
ertion by the application only of the natural ftimulus, and thus 
a libration of the fenforial exertion between one excefs and the 
other continues for two or three days, where the ftimulus was 
Vol. I. I violent 58 
OF STIMULUS 
Sect. XII. 3. 1. 
violent in degree ; and for weeks in fome fevers, from the flim- 
ulus of contagious matter. 
But if a fecond dofe of opium be exhibited before the fibres 
have regained their natural quantity of fenforial power, its cf- 
fect will be much lefs than the former, becaufe the fpirit of an- 
imation or fenforial power is in part exhaufled by the previous 
excefs of exertion. Hence all medicines repeated too frequent- 
ly gradually lofe their effect, as opium and wine. Many things 
of difagreeable tafle at firft ceafe to be difagreeable by frequent 
repetition, as tobacco ; grief and pain gradually diminifh, and 
at length ceafe altogether, aqd hence life itfelf becomes toler- 
able. 
Befides the temporary diminution of the fpirit of animation 
or fenforial power, which is naturally ftationary or refidcnt in 
every living fibre, by a fingle exhibition of a powerful ftimulus, 
the contractile fibres themfclves, by the perpetual application of 
a new quantity of ftimulus, before they have regained their nat- 
ural quantity of fenforial power, appear to fuffer in their capa- 
bility of receiving fo much as the natural quantity of fenforial 
oowcr ; and hence a permanent deficiency of fpirit of anima- 
tion takes place, however long the ftimulus may have been 
withdrawn. On this caufe depends the permanent debility of 
thofe, who have been addicted to intoxication, the general weak- 
nefs of old age, and the natural debility or inirritability of thofe, 
who have pale fkins and large pupils of their eyes. 
There is a curious phenomenon belongs to this place, which 
has always appeared difficult of folution ; and that is, that opi- 
um or aloes may be exhibited in fmall dofes at firft, and gradu- 
ally increafed to very large ones without producing ftupor or 
diarrhoea. In this cafe, though the opium and aloes are given 
in fuch fmall dofes as not to produce intoxication or catharfis, 
yet they are exhibited in quantities fufficient in fome degree to 
exhauft the fenforial power, and hence a ftronger and a ftrong- 
er dofe is required ; otherwife the medicine would foon ceafe 
to a St at all. 
On the contrary, if the opium or aloes be exhibited in a large 
dofe at firft, fo as to produce intoxication or diarrhoea ; after a 
few repetitions the quantity of either of them may be diminifh- 
ed, and they will ftill produce this effedt. -For the more pow- 
erful ftimulus diflevers the progreffive catenations of animal mo- 
tions, defcribed in SecSt. XVII. and introduces a new link be- 
tween them ; whence every repetition flrengthens this new af- 
fociation or catenation, and the ftimulus may be gradually de- 
creafed, or be nearly withdrawn, and yet the efiedl (hall con- 
tinue ; becaufe the fenforial power of affociation or catenation 
being Sect. XII. 3. 2. 
AND EXERTION. 
being united with the ftimulus, increafes in energy with every 
repetition of the catenated circle ; and it is by theie means that 
all the irritative affociations of motions are originally produced. 
Thus if the Peruvian bark be given in the intervals between 
the fits of intermittent fever in fuch fmall dofes, as not to pre- 
vent the returns of fever, the conftitution ceafes to obey its 
ftimulus, and the difeafe cannot be cured even by the largeft 
dofes of bark, unlefs the patient ceafes to take any for a few 
days previous to the exhibition of larger dofes. But if large 
dofes be at firft exhibited, fo as to prevent the return of fever, 
fmall ones taken afterwards will continue to prevent the return 
of it. 
2. When a ftimulus is repeated at fuch diftant intervals of 
time, that the natural quantity of fenforial power becomes com- 
pletely reftored in the acting fibres, it will aCt with the fame en- 
ergy as when firft applied. Hence thofe who have lately accuf- 
tomed themfelves to large dofes of opium by beginning with 
fmall ones, and gradually increafing them, and repeating them 
frequently, as mentioned in the preceding paragraphs ; if they 
intermit the ufe of it for a few days only, muft begin again with 
as fmall dofes as they took at firft, other wife they will experi- 
ence the inconveniences of intoxication. 
On this circumftance depend the conftant unfailing effeCts of 
the various kinds of ftimulus, which excite into action all the 
vafcular fyftems in the body ; the arterial, venous, abforbent, 
and glandular veiTels, arc brought into perpetual unwearied ac- 
tion by the fluids, which are adapted to ftimulate them ; but 
thefe have the fenforial power of aflbciation added to that of ir- 
ritation, and even in fome degree that of fenfation, and even of 
volition, as will be fpoken of in their places; and life itfelf is thus 
carried on by the production of fenforial power being equal to its 
wafte or expenditure in the perpetual movement of the vafcu- 
lar organization. 
3. When a ftimulus is repeated at uniform intervals of time 
with fuch diftances between them, that the expenditure of fen- 
forial power in the aCting fibres becomes completely renewed, 
the effect is produced with greater facility or energy. For the 
fenforial power of aflbciation is combined with the fenforial 
power of irritation, or, in common language, the acquired hab- 
it aflifts the power of the ftimulus. 
This circumftance not only obtains in the annual and diur- 
nal catenations of animal motions explained in SeCt. XXXVI. 
but in every lefs circle of aCtions or ideas, as in the burthen of 
a fong, or the iterations of a dance ; and conftitutcs the pleaf- 
ure 
59 60 
OF STIMULUS 
Sect. XII. 3. 4. 
ure we receive from repetition and imitation ; as treated of in 
Sect. XXII. 2. 
4. When a ftimulus has been many times repeated at uni- 
form intervals, fo as to produce the complete action of the or- 
gan, it may then be gradually diminiffied, or totally withdrawn, 
and the adtion of the organ will continue. For the fenforial 
power of affociation becomes united with that of irritation, and 
by frequent repetition becomes at length of fufficient energy to 
carry on the new link in the circle of actions, without the irri- 
tation which at firft introduced it. 
Hence, when the bark is given at ftated intervals for the 
cure of intermittent fevers, if fixty grains of it be given every 
three hours for the twenty-four hours preceding the expected 
paroxyfm, fo as to Simulate the defective part of the fyftem in- 
to adtion, and by that means to prevent the torpor or quiefcence 
of the fibres, which conftitutes the cold fit \ much lefs than half 
the quantity, given before the time at which another paroxyfm 
of quiefcence would have taken place, will be fufficient to pre- 
vent it; became now the fenforial power, termed affociation, 
acts in a twofold manner. Firft, in refpedt to the period of 
the.catenation in which the cold fit was produced, which is now 
diffevered by the ftronger ftimulus of the firft dofes of the bark; 
and, fecondjy, becaufe each dofe of bark being repeated at peri- 
odical times, has its eftedt increafed by the fenforial faculty of 
affociation being combined with that of irritation. 
Now, when fixty grains of Peruvian bark are taken twice a 
day, fuppofe at ten o'clock and at fix, for a fortnight, the irrita- 
tion excited by this additional ftimulus becomes a part of the 
diurnal circle of actions, and will at length carry on the increaf- 
ed action of the fyftem without the affiftance of the ftimulus of 
the bark. On this theory the bitter medicines, chalybeates, 
and opiates in appropriated dofes, exhibited for a fortnight, give 
permanent ftrength to pale feeble children, and other weak 
conftitutions. 
5. When a defeat of ftimulus, as-of heat, recurs at certain 
diurnal intervals, which induces fome torpor or quiefcence of 
a part of the fyftem, the diurnal catenation of actions becomes 
difordcred, and a new affociation with this link of torpid action 
is formed j on the next period the quantity of quiefcence will be 
increafed, fuppofe the fame defect of ftimulus to recur, becaufe 
now the new affociation confpires with the defective irritation 
in introducing the torpid action of this part of the diurnal cat- 
enation. In this manner many fever-fits commence, where the 
patient is for fome days indifpofed at certain hours, before the 
cold Sect. XII. 3. 6. 
AND EXERTION. 
61 
cold paroxyfm of fever is completely formed. See Seel. XVII. 
3. 3. on Catenation of Animal Motions. 
6. If a ftimulus, which at firft excited the affected organ into 
fo great exertion as to produce fenfation, be continued for a 
certain time, it will ceafe to produce fenfation both then and 
when repeated, though the irritative motions in confequence of 
it may continue or be re-excited. 
Many catenations of irritative motions were at firft fucceed* 
ed by fenfation, as the apparent motions of objects when we 
walk paft them, and probably the vital motions themfelves i$ 
the early ftate of our exiftence. But as thofe fenfations were 
followed by no* movements of the fyftem in confequence of 
them, they gradually ceafed to be produced, not being joined to 
any fucceeding link of catenation. Hence contagious matter, 
which has for fome weeks ftimulated the fyftem into great and 
permanent fenfation, ceafes afterwards to produce general fenfa- 
tion, or inflammation, though it may ftill induce topical irrita- 
tions. See Sect. XXXIII. 2. 8. XIX. 10. 
Our abforbent fyftem then feems to receive thofe contagious 
matters, which it has before experienced, in the fame manner as 
it imbibes common inoifture or other fluids; that is, without 
being thrown into fo violent action as to produce fenfation ; the 
confequence of which is an increafe of daily energy or activity, 
till inflammation and its confequences fucceed. 
7. If a ftimulus excites an organ into fuch violent contrac- 
tions as to produce fenfation, the motions of which organ had 
not ufually produced fenfation,.this new fenforial power, added 
to the irritation occafioned by the ftimulus, increafes the activ- 
ity of the organ. And if this activity be catenated with the di- 
urnal circle of actions, an increafing inflammation is produced ; 
as in the evening paroxyfms of fmall-pox, and other fevers with 
inflammation. And hence fchirrous tumours, tendons and 
membranes, and probably the arteries themfelves become in- 
flamed, when they are ftrongly ftimulated. 
IV. Of Stimulus greater than natural. 
i. A quantity of ftimulus greater than natural, producing an 
increafed exertion of fenforial power, whether that exertion be 
in the mode of irritation, fenfation, volition, or aflbeiation, dimin* 
ifhes the general quantity of it. This fa£t is obfervable in the 
progrefs of intoxication, as the increafed quantity or energy of 
the irritative motions, owing to the ftimulus of vinous fpirit, in- 
troduces much plcafurable fenfation into the fyftem, and much 
exertion of mufcular or fenfual motions in confequence of this 
increafed 62 
OF STIMULUS 
Sect. XII. 4. 2. 
increafed fenfation ; the voluntary motions, and even the aflbci- 
ate ones, become much impaired or diminifhed ; and delirium 
and (daggering fucceed. See Se£h XXL on Drunkennefs. 
And hence the great proftration of the ftrength of the locomo- 
tive mufcles in fome fevers, is owing to the exhauftion of fenfo- 
rial power by the increafed aCHon of the arterial fyftem. 
In like manner a ftimulus greater than natural, applied to a 
part of the fyftem, increafes the exertion of fenforial power in 
that part, and diminifties it in fome other part. As in the com- 
mencement of fcarlet fever, it is ufual to fee great rednefs and 
heat on the faces and breafts of children, while at the fame time 
their feet are colder than natural; partial heats are obfervable 
in other fevers with debility, and are generally attended with 
torpor or quiefcence of fome other part of the fyftem. But 
thefe partial exertions of fenforial power are fometimes attend- 
ed with increafed partial exertions in other parts of the fyftem, 
which fympathize with them, as the flufhing of the face after a 
full meal. Both thefe therefore are to be afcribed to fympathet- 
ic aflbeiations, explained in SeCt. XXXV. and not to general 
exhauftion or accumulation of fenforial power. 
2. A quantity of ftimulus greater than natural, producing an 
increafed exertion of fenforial power in any particular organ, 
diminifhes the quantity of it in that organ. This appears from 
the contractions of animal fibres being not fo eafily excited by a 
Jefs ftimulus after the organ has been fubjeCted to a greater. 
Thus after looking at any luminous objeft of a fmall fize, as at 
the fetting fun, for a fhort time, fo as not much to fatigue the 
eye, this part of the retina becomes lefs fenfible to fmaller quan- 
tities of light; hence when the eyes are turned on other lefs lu- 
minous parts of the iky, a dark fpot is feen refembling the flrape 
of the fun, or other luminous objeCt which we laft behold. Sec 
Sect. XL. No. 2. 
Thus we are fome time before we can diftinguilh objeCt^ in 
an obfeure room after coming from bright day-light, though the 
iris prefently contracts itfelf. We are not able to hear weak 
founds after loud ones. And the ftomachs of thofe who have 
been much habituated to the ftronger ftimulus of fermented or 
fpirituous liquors, are not excited into due aCtion by weaker ones. 
3. A quantity of ftimulus fomething greater than the laft 
mentioned, or longer continued, induces the organ into fpaf- 
modic aCtion, which ceafes and recurs alternately. Thus on 
looking for a time on the fetting fun, fo as not greatly to fatigue 
the fight, a yellow fpeCtrum is feen when the eyes are clofed 
and covered, which continues for a time, and then difappears 
and recurs repeatedly before it entirely vanilhes. See SeCt. XL. 
No. Sect. XII. 4. 4. 
AND EXERTION. 
63 
No. 5. Thus the aCtion o£ vomiting ceafes and is renewed by 
intervals, although the emetic drug is thrown up with the firlt 
effort. A tenefmus continues by intervals fome time after the 
exclufion of acrid excrement; and the pulfations of the heart of 
a viper are faid to continue fome time after it is cleared from 
its blood. 
In thefe cafes the violent contractions of the fibres produce 
pain according to law 4 ; and this pain conftitutes an additional 
kind or quantity of excitement, which again induces the fibres 
into contraction, and which painful excitement is again renew- 
ed, and again induces contractions of the fibres with gradually 
diminifhing effeCt. 
4. A quantity of ftimulus greater than that laft mentioned, or 
longer continued, induces the antagonift mufcles into fpafmodic 
aCtion. This is beautifully illuftrated by the ocular fpeCtra de- 
fcribed in SeCt. XL. No. 6. to which the reader is referred. 
From thofe experiments there is reafon to conclude that the fa- 
tigued part of the retina throws itfelf into a contrary mode of 
aCtion like ofeitation or pandiculation, as foon as the ftimulus, 
which has fatigued it, is withdrawn ; but that it ftili remains li- 
able to be excited into aCtion by any other colours except the 
colour with which it has been fatigued. Thus the yawning and 
ftretching the limbs after a continued aCtion or attitude feems 
occafioned by the antagonift mufcles being ftimulated by their 
extenfion during the contraCtions of thofe in aCtion, or in the 
Ctuation in which that aCtion laft left them. 
5. A quantity of ftimulus greater than the laft, or longer con- 
tinued, induces variety of convulfions or fixed fpafms either of 
the afFeCted organ or of the moving fibres in the other parts of 
the body. In refpeCt to the fpeCtra in the eye, this is well il- 
luftrated in No. 7 and 8, of SeCt. XL. Epileptic convulfions, as 
the emprofthotonos and opifthotonos, with the cramp of the calf 
of the leg, locked jaw, and other cataleptic fits, appear to origi- 
nate from pain, as fome of thefe patients fcream aloud before 
the convulfion takes place ; which feems at firft to be an effort 
to relieve painful fenfation, and afterwards an effort to prevent it. 
In thefe cafes the violent contraCtions of the fibres produce fo 
much pain, as to conftitute a perpetual excitement 5 and that in 
fo great a degree as to allow but fmall intervals of relaxation of 
the contracting fibres as in convulfions, or no intervals at all as 
in fixed fpafms. 
6. A quantity of ftimulus greater than the laft, or longer con- 
tinued, produces a paralyfis of the organ. In many cafes this 
paralyfis is only a temporary effeCt, as on looking long on a fmall 
area of bright red filk placed on a fheet pf white paper on the 
floor 64 
OF STIMULUS 
Sect. XII. 5. 1. 
floor in a ftrong light, the red filk gradually becomes paler, and 
at length difappears; which evinces that a part of the retina, by 
being violently excited, becomes for a time unaffected by the 
ftimulus of that colour. Thus cathartic medicines, opiates, poi- 
fons, contagious matter, ceafe to influence our fyftem after it has 
been habituated to the ufe of them, except by the exhibition of 
increafed quantities of them ; our fibres not only become unaf- 
fected by ftimuli, by which they have previoufly been violently 
irritated, as by the matter of the fmall-pox or meafles ; but they 
alfo become unaffected by fenfation, where the violent exertions, 
which difabled them, were in confequence of too great quantity 
of fenfation. And laftly the fibres, which become difobedient 
to volition, are probably difabled by their too violent exertions 
in confequence of too great a quantity of volition. 
After every exertion of our fibres a temporary paralyfis fuc- 
cceds, whence the intervals of all mufcular contraflions, as men- 
tioned in No. 3 and 4 of this Section; the immediate caufe of 
thefe more permanent kinds of paralyfis is probably owing in the 
fame manner to the too great exhauftion of the fpirit of anima- 
tion in the affeCted part; fo that a ftronger ftimulus is required, 
or one of a different kind from that, which occafioned thofe too 
violent contractions, to again excite the affected organ into ac- 
tivity ; and if a ftronger ftimulus could be applied, it muft 
again induce paralyfis. 
For thefe powerful ftimuli excite pain at the fame time, that 
they produce irritation; and this pain not only excites fibrous 
motions by its ftimulus, but it alfo produces volition ; and thus 
all thefe ftimuli acting at the fame time, and fometimes with 
the addition of their affociations, produce fo great exertion as to 
expend the whole of the fenforial power in the affeCted fibres. 
V. Of Stimulus lefs than natural. 
i. A quantity of ftimulus lefs than natural, producing a de- 
creafed exertion of fenforial power, occaficns an accumulation 
of the general quantity of it. This circumftance is obfervable 
in the haeiniplegia, in which the patients are perpetually mov- 
ing the mufcles, which are unaffected. On this account we 
awake with greater vigour after Heep, becaufe during fo many 
hours, the great ufual expenditure of fenforial power in the per- 
formance of voluntary actions, and in the exertions of our or- 
gans of fenfe, in confequence of the irritations occanoned by ex- 
ternal objedts had been fufpended, and a confequent accumula- 
tion had taken place. 
In like manner the exertion of the fenforial power lefs than 
• natural Sect. XII. 5. 2. 
AND EXERTION. 
65 
natural in one part of the fyftem, is liable to produce an increafe 
of the exertion of it in fome other part. Thus by the action of 
vomiting, in which the natural exertion of the motions of the 
ftomach are deftroyed or diminiihed, an increafed abforption of 
the pulmonary and cellular lymphatics is produced, as is known 
by the increafed abforption of the fluid deposited in them in 
dropfical cafes. But thefe partial quiefcences of fenforial power- 
are alfo fometimes attended with other partial quiefcences, which 
fympathize with them, as cold and pale extremities from hun- 
ger. Thefe therefore are to be afcribed to the aflbciations of 
fympathy explained in Se<ft. XXXV. and not to the general 
accumulation of fenforial power. 
2. A quantity of ftimulus lefs than natural, applied to fibres 
previoufly accuftomed to perpetual ftimulus, is fucceeded by ac- 
cumulation of fenforial power in the affe&ed organ. The truth 
of this propofition is evinced, becaufe a ftimulus lefs than nat- 
ural, if it be fomewhat greater than that above mentioned, will 
excite the organ fo circumftanced into violent activity. Thus 
on a frofty day with wind, the face of a perfon expofed to the 
wind is at firft pale and fhrunk ; but on turning the face from 
the wind, it becomes foon of a glow with warmth and flulhing. 
The glow of the Ikin in emerging from the cold-bath is owing 
to the fame caufe. 
It does not appear, that an accumulation of fenforial power 
above the natural quantity is acquired by thofe mufcles, which 
are not fubjeft to perpetual ftimulus, as the locomotive mufcles : 
thefe, after the greateft fatigue, only acquire by reft their ufual 
aptitude to motion; whereas the vafcular fyftem, as the heart 
and arteries, after a fhort quiefcence, are thrown into violent ac- 
tion by their natural quantity of ftimulus. 
Neverthelefs by this accumulation of fenforial power during 
the application of decreafed ftimulus, and by the exhauftion of 
it during the action of increafed ftimulus, it is wifely provided, 
that the actions of the vafcular mufcles and organs of fenfe are 
not much deranged by fmall variations of ftimulus ; as the quan- 
tity of fenforial power becomes in fome meafure inverfely as the 
quantity of ftimulus. 
3. A quantity of ftimulus lefs than that mentioned above, and 
continued for fome time, induces pain in the affected organ, as 
the pain of cold in the hands, when they are immerfed in fnow, 
is owing to a deficiency of the ftimulation of heat. Hunger is 
a pain from the deficiency of the ftimulation of food. Pain 
in the back at the commencement of ague-fits, and the head- 
achs which attend feeble people, are pains from defeat of ftim- 
ulus, and are hence relieved by opium, eflentiaroils,fpirit of wine. 
Vol. I. Is, As 66 
OF STIMULUS 
Sect. XII. 5. 4. 
As the pains, which originate from defeCt of ftimulus, only 
occur in thofe parts of the fyftem, which have been previoufly 
fubjeCted to perpetual ftimulus; and as an accumulation of fen- 
forial power is produced in the quiefcent organ along with the 
pain, as in cold or hunger, there is reafon to believe, that the 
pain is owing to the accumulation of fenforial power. For, in 
the locomotive mufcles, in the retina of the eye, and other or- 
gans of fenfe, no pain occurs from the abfence of ftimulus, nor 
any great accumulation of fenforial power beyond their natural 
quantity, fince thefe organs have not been ufed to a perpetual 
fupply of it. There is indeed a greater accumulation occurs in 
the organ of vifion after its quiefcence, becaufe it is fubjeft to 
more conftant ftimulus. 
4. A certain quantity of ftimulus lefs than natural induces 
the moving organ into feebler and more frequent contractions, 
as mentioned in No. I. 4. of this Section. For each contraCiion 
moving through a lefs fpace, or with lefs force, that is, with lefs 
expenditure of the fpirit of animation, is fooner relaxed, and the 
fpirit of animation derived at each interval into the aCting fibres 
being lefs, thefe intervals likewife become fhorter. Hence the 
tremors of the hands of people accuftomed to vinous fpirit, till 
they take their ufual ftimulus ; hence the quick pulfe in fevers 
attended with debility, which is greater than in fevers attended 
with ftrength; in the latter the pulfe feldom beats above 120 
times in a minute, in the former it frequently exceeds 140. 
It muft be obferved, that in this and the two following arti- 
cles the decreafed action of the fyftem is probably more fre- 
quently occafioned by deficiency in the quantity of fenforial 
power, than in the quantity of ftimulus. Thus thofe feeble 
conftitutions which have large pupils of their eyes, and aft who 
labour under nervous fevers, feem to owe their want of natural 
quantity of aCtivity in the fyftem to the deficiency of fenforial 
power ; fince, as far as can be feen, they frequently poffefs the 
natural quantity of ftimulus. 
5. A certain quantity of ftimulus, lefs than that above men- 
tioned, inverts the order of fuccelfive fibrous contraCtions ; as 
in vomiting the vermicular motions of the ftomach and duode- 
num are inverted, and their contents ejected, which is probably 
owing to the exhauftion of the fpirit of animation in the aCting 
mufcles by a previous excelfive ftimulus, as by the root of ipecac- 
uanha, and the confequent defeCt of fenforial power. The 
fame retrograde motions affeCt the whole inteftinal canal in 
ileus ; and the cefophagus in globus hyftericus. See this fur- 
ther explained in SeCt. XXIX. No. 11. on Retrograde Motions. 
I muft obferve, alfo, that fomething fimilar happens in the 
production Sect. XII. 5. 6. 
AND EXERTION. 
67 
production of our ideas, or fenfual motions, when they are too 
weakly excited; when any one is thinking intenfely about one 
thing, and carelefsly converfing about another, he is liable to ufe 
the word of a contrary meaning to that which he defigned, as 
cold weather for hot weather, fummer for winter. 
6. A certain quantity of ftimulus, lefs than that above men- 
tioned, is fucceeded by paralyfis, firft of the voluntary and fenfi- 
tive motions, and afterwards of thofe of irritation and of aflbeia- 
tion, which conftitutes death. 
VI. Cure of increafed Exertion. 
I. The cure, which nature has provided for the increafed ex- 
ertion of any part of the fyftem, confifts in the confequent ex- 
penditure of the fenforial power. But as a greater torpor fol- 
lows this exhauftion of fenforial power, as explained in the next 
paragraph, and a greater exertion fucceeds this torpor, the con- 
ftitution frequently finks under thefe increafing librations be- 
tween exertion and quiefcence ; till at length complete quief- 
cence, that is, death, clofes the fcene. 
For, during the great exertion of the fyftem in the hot fit of 
fever, an increafc of ftimulus is produced from the greater mo- 
mentum of the blood, the greater diftention of the heart and ar- 
teries, and the increafed production of heat, by the violent ac- 
tions of the fyftem occafioned by this augmentation of ftimulus, 
the fenforial power becomes diminilhed in a few hours much 
beneath its natural quantity, the veflels at length ceafe to obey 
even thefe great degrees of ftimulus, as Ihewn in SeCt. XL. 9. 
1. and a torpor of the whole or of a part of the fyftem enfues. 
Now as this fecond cold fit commences with a greater defi- 
ciency of fenforial power, it is alfo attended with a greater defi- 
ciency of ftimulus than in the preceding cold fit, that is, with lefs 
momentum of blood, lefs diftention of the heart. On this ac- 
count the fecond cold fit becomes more violent and of longer 
duration than the firft ; and as a greater accumulation of fenfo- 
rial power muft be produced before the fyftem of veifels will 
again obey the diminilhed ftimulus, it follows, that the fecond 
hot fit of fever will be more violent than the former one. And 
that unlefs fome other caufes counteract either the violent exer- 
tions in the hot fit, or the great torpor in the cold fit, life will 
at length be extinguilhed by the expenditure of the whole of the 
fenforial power. And from hence it appears, that the true 
means of curing fevers muft be fuch as decreafe the action of 
the fyftem in the hot fit, and increafc it in the cold fit; that is, 
fuch 68 
OF STIMULUS 
Sect. XII. d. 2. 
fuch as prevent the too great diminution of fenforial power in 
the hot fit, and the too great accumulation of it in the cold one. 
2. Where the exertion of the fenforial powers is much in- 
creafed, as in the hot fits of fever or inflammation, the follow- 
ing are the ufual means of relieving it. Decreafe the irritations 
by blood-letting, and other evacuations; by cold water taken 
into the ftomach, or injected as an enema, or ufed externally; 
by cold air breathed into the lungs, and diffufed over the Ikin ; 
with food of lefs ftimulus than the patient has been accuftom- 
cd to. 
3. As a cold fit, or paroxyfm of inactivity of fome parts of 
the fyftem, generally precedes the hot fit, or paroxyfm of exer- 
tion, by which the fenforial power becomes accumulated, this 
cold paroxyfm fhould be prevented by ftimulant medicines and 
diet, as wine, opium, bark, warmth, cheerfulnefs, anger, furprife. 
4. Excite into greater aCtion fome other part of the fyftem, by 
which means the fpirit of animation may be in part expended, 
and thence the inordinate actions of the difeafed part may be 
leflened. Hence when a part of the Ikin arts violently, as of 
the face in the eruption of the fmall-pox, if the feet be cold they 
fhould be covered. Hence the ufe of a blifter applied near a 
topical inflammation. Hence opium and warm bath relieve 
pains both from excefs and defeCt of ftimulu^. 
5. Firft increafe the general ftimulation above its natural 
quantity, which may in fome degree exhauft the fpirit of ani- 
mation, and then decreafe the ftimulation beneath its natural 
quantity. Hence after fudorific medicines and warm air, the 
application of refrigerants may have greater efFeCl, if they could 
be adminiftered without danger of producing too great torpor 
of fome part of the fyftem ; as frequently happens to people in 
health from coming out of a warm room into the cold air, by 
which a topical inflammation iq confequence of torpor of the 
mucous membrane of the noftril is produced, and is termed a 
cold in the head. 
VIL Cute of decreaftd Exertion. 
i. Where the exertion o£ the fenforial powers is much de- 
creafed, as in the cold fits of fever, a gradual accumulation of 
the fpirit of animation takes place ; as occurs in all cafes where 
inactivity or torpor of a part of the fyftem exifts ; this accumu- 
lation of fenforial power increafes, till ftimuli lefs than natural 
are fufficient to throw it into aCtion, then the cold fit ceafes ; 
and from the action of the natural ftimuli a hot one fucceeds 
with increafed activity of the whole fyftem. 
So Sect. XII. 7. 2. 
AND EXERTION. 
69 
So in fainting fits, or fyncope, there is a temporary deficien- 
cy of fenforial exertion, and a confequent quiefcence of a great 
part of the fyftem. This quiefcence continues, till the fenforial 
power becomes again accumulated in the torpid organs ; and 
then the ufual diurnal ftimuli excite the revivefcent parts again 
into action ; but as this kind of quiefcence continues but a 
fhort time compared to the cold paroxyfm of an ague, and lefs 
affefls the circulatory fyftem, a lefs fuperabundancy of exertion 
fucceeds in the organs previoufly torpid, and a lefs excefs of ar- 
terial activity. See Sefl. XXXIV. i. 6. 
2. In the difeafes occafioned by a defeat of fenforial exertiofi, 
as in cold fits of ague, hyfteric complaint, and nervous fever, 
the following means arethofe commonly ufed. i. Increafethe 
ftimulation above its natural quantity for fome weeks, till a new 
habit of more energetic contraflion of the fibres is eftablifhed. 
This is to be done by wine, opium, bark, fteel, given at exafl 
periods, and in appropriate quantities ; for if thefe medicines be 
given in fuch quantity, as to induce the leaft degree of intoxica- 
tion, a debility fucceeds from the ufelefs exhauftion of fpirit of 
animation in confequence of too great exertion of the muffles 
or organs of fenfe. To thefe irritative ftimuli ftiould be added 
the fenfitive ones of cheerful ideas, hope, affeflion. 
3. Change the kinds of ftimulus. The habits acquired by 
the conftitution depend on fuch nice circumftances, that when 
one kind of ftimulus ceafes to excite the fenforial power into 
the quantity of exertion neceffary to health, it is often fufficient 
to change the ftimulus for another apparently fimilar in quanti- 
ty and quality. Thus when wine ceafes to ftimulate the con- 
ftitution, opium in appropriate dofes fupplies the defefl ; and 
the contrary. This is alfo obferved in the effefls of cathartic 
medicines, when one lofes its power, another, apparently lefs 
efficacious, will fucceed. Hence a change of diet, drink, and 
ftimulating medicines, is often advantageous in difeafes of de- 
bility. 
4. Stimulate the organs, whofe motions are aflbciated with 
the torpid parts of the fyftem. The aflions of the minute vef- 
fels of the various parts of the external Ikin are not only aflbciated 
with each other, but are ftrongly aflbciated with thofe of fome of 
the internal membranes, and particularly of the ftomach. Hence 
when the exertion of the ftomach is lefs than natural, and indi- 
geflion and heartburn fucceed, nothing fo certainly removes 
thefe fymptoms as the ftimulus of a blifter on the back. The 
coldnefs of the extremities, as of the nofe, ears, cr fingers, arc 
hence the beft indication for the fuccefsful application of blifters. 
5. Dccreafc the ftimulus for a time. By leflening the quan- 
tity 70 
OF STIMULUS 
Sect. XII. 7. 6. 
tity of heat for a minute or two by going into the cold bath, a 
great accumulation of fenforial power is produced ; for not on- 
ly the minute veflels of the whole external Ikin for a time be- 
come inactive, as appears by their palenefs ; but the minute 
veflels of the lungs lofe much of their activity alfo by concert 
with thofe of the (kin, as appears from the difficulty of breath- 
ing at firft going into cold water. On emerging from the bath 
the fenforial power is thrown into great exertion by the ftimu- 
lus of the common degree of the warmth of the atmofphere, and 
a great production of animal heat is the confequence. The 
longer a perfon continues in the cold bath the greater muft be 
the prefent inertion of a great part of the fyftem, and in confe- 
quence a greater accumulation of fenforial power. Whence 
M. Pome recommends fome melancholy patients to be kept 
from two to fix hours in fpring-water, and in baths ftill colder. 
6. Decrcafe the ftimulus for a time below the natural, and 
then increafe it above natural. The effedt of this procefs, im- 
properly ufed, is feen in giving much food, or applying much 
warmth, to thofe who have been previously expofed to great 
hunger, or to great cold. The accumulated fenforial power is 
thrown into fo violent exertion, that inflammations and mortifi- 
cations fupervene, and death clofes the cataftrophe. In many 
difeafes this method is the moft fuccefsful; hence the bark in 
agues produces more certain effect after the previous exhibition 
of emetics. In difeafes attended with violent pain, opium has 
double the effect, if venefeCtion and a cathartic have been pre- 
vioufly ufed. On this feems to have been founded the fuccefs- 
ful practice of S; denham, who ufed venefedtion and a cathartic 
in chlorofis before the exhibition of the bark, fteel, and opiates. 
7. Prevent any unneceffary expenditure of fenforial power. 
Hence in fevers with debility, a decumbent pofture is preferred, 
with filence, little light, and fuch a quantity of heat as may 
prevent any chill fenfation, or any coldnefs of the extremities. 
The pulfe of patients in fevers with debility increafes in fre- 
quency above ten pulfations in a minute on their rifing out of 
bed. For the expenditure of fenforial power to preferve an 
erect pofture of the body adds to the general deficiency of it, 
and thus affeefs the circulation. 
8. The longer in time and the greater in degree the quiefcence 
or inertion of an organ has been, fo that it ftill retains life or 
excitability, the lefs ftimulus Ihould at firft be applied to it. 
The quantity of ftimulation is a matter of great nicety to de- 
termine, where the torpor or quiefcence of the fibres has been 
experienced in a great degree, or for a confiderablc time, as in 
cold fits of the ague, in continued fevers with great debility, or 
in Sect. XII. 7. 8. 
AND EXERTION. 
71 
in people famiihed at fea, or perifhing with cold. In the two 
laft cafes, very minute quantities of food ihould be firft fuppli- 
ed, and very few additional degrees of heat. In the two form- 
er cafes, but little ftimulus of wine or medicine, above what 
they had been lately accuftomed to, ihould be exhibited, andl 
this at frequent and ftated intervals, fo that the effect of one 
quantity may be obferved before the exhibition of another. 
If thefe circumftances are not attended to, as the fenforial 
power becomes accumulated in the quiefeent fibres, an inordi- 
nate exertion takes place by the increafe of ftimulus acting on 
accumulated quantity of fenforial power, and either the paral- 
yfis, or death of the contractile fibres enfues, from the total ex- 
penditure of the fenforial power in the affected organ, owing to 
this increafe of exertion, like the debility after intoxication. 
Or, fecondly, the violent exertions above mentioned produce 
painful fenfation, which becomes a new ttimulus, and by thus 
producing inflammation, and increafing the activity of the fibres 
already too great, fooner exhaufts the whole of the fenforial 
power in the ailing organ, and mortification, that is, the death 
of the part, fupervenes. 
Hence there have been many inftances of people, whofe 
limbs have been long benumbed by expofure to cold, who have 
loft them by mortification on their being too haftily brought to 
the fire ; and of others, who were nearly famifhed at fea, who 
have died foon after having taken not more than an ufual meal 
of food. I have heard of two well-attefted inftances of patients 
in the cold fit of ague, who have died from the exhibition of 
gin and vinegar, by the inflammation which enfued. And in 
many fevers attended with debility, the unlimited ufe of wine, 
and the wanton application of blifters, I believe, has deftroyed 
numbers by the debility confequent to too great ftimulation, 
that is, by the exhauftion of the fenforial power by its inordi- 
nate exertion. 
Wherever the leaft degree of intoxication exifts, a proportion- 
al debility is the confequence ; but there is a golden rule by 
which the neceffary and ufeful quantity of ftimulus in fevers 
with debility may be afeertained. When wine or beer is ex- 
hibited either alone or diluted with water, if the pulfc becomes 
flower the ftimulus is of a proper quantity ; and ihould be re- 
peated every two or three hours, or when the pulfe again be- 
comes quicker. 
In the chronical debility brought on by drinking fpirituous or 
fermented liquors, there is another golden rule by which I have 
fuccefsfully directed the quantity of fpirit which they may fafe- 
ly leffen, for there is no other means by w'hich they can recov- 
er 72 
OF STIMULUS, &c. 
Sect. XTI. 8. 
er their health. It Ihould be premifed, that where the power 
of digeftion in thefe patients is totally deftroyed, there is not 
much reafon to expeft a return to healthful vigour. 
I have directed feveral of thefe patients to omit one fourth 
part of the quantity of vinous fpirit they have been lately ac- 
cuftomed to, and if in a fortnight their appetite increafes, they 
are advifed to omit another fourth part ; but if they perceive 
that their digeftion becomes impaired from the want of this 
quantity of fpirituous potation, they are advifed to continue as 
they are, and rather bear the ills they have, than rifle the en- 
counter of greater. At the fame time flefli-meat with or with- 
out fpice is recommended, with Peruvian bark and fteel in fmall 
quantities between their meals, and half a grain of opium, or a 
grain, with five or eight grains of rhubarb at night. 
VIII. Conclufion. 
It may be aiked, if ftimulus exhaufts the fenforial power, 
can an increafe of it ever be ufed with advantage, where the 
fenforial power is already in too fmall quantity ? We muft rec- 
olleft, that the fenforial power is produced in the brain and fpi- 
nal marrow by the fibrous a&ions of thofe glands like other fe- 
cretions: and that hence an increafed action of thefe glands by 
an adapted ftimulus, or by aflbciation of motions, may increafe 
the quantity of fenforial power, which increafed actions of the 
fyftem may be continued by habit, after the ftimulus is with- 
drawn. Thus fome kinds of ftimuli affect particular parts of 
the fyftem, as blifters affect the Ikin, and the ftomach by its af- 
fociation with the fkin ; emetics affect the ftomach, cathartics 
the inteftines ; and fea-falt the perfpirable glands or capillaries : 
but it is probable, that wine and opium affect the whole fyftem ; 
and, when given in fmall repeated quantities, that they increafe 
the fecretion of fenforial power, either by their immediate ftim- 
ulus or by aflbciation, and that the ftrength of convalefcents is 
recruited, as they are thus enabled to digeft more food, and 
that of a fomewhat more ftimulating quality. The Peruvian 
bark, and arfenic, in the cure of agues, probably act in a fimi- 
lar manner on the ftomach, and on the parts aflbciated with it, 
fo as to increafe their powers of action ; but not not on the 
whole fyftem, as general heat is not produced by them. 
SECT. Sect. XIII. r. i. 
OF VEGETABLE, &c. 
73 
SECT. XIII. 
OF VEGETABLE ANIMATION. 
I. I. Vegetables are irritable, mimofa, dionaa mufcipula. V°geta- 
ble fecretions. 2. Vegetable buds are inferior animals, are liable 
to greater or lefs irritability. II. Stamens and pifils of plants 
jhevo marks of fenfibihty. III. Vegetables poffefs fame degree op 
* Volition. IV. Motions of plants are affociated like thofe of ani- 
mals. V. I. Vegetable fracture like that of animals, their an- 
thers andfigmas are living creatures. Male fovoers of Vallif- 
neria. 2. Whether vegetables poffefs ideas ? They have organs 
of fenfe, as of touch and fmell, and ideas of external things ? 
I. i. The fibres of the vegetable world, as well as thofe of 
the animal, are excitable into a variety of motions by irritations 
of external objects. This appears particularly in the mimofa 
or fenfitive plant, whofe leaves contract on the flighted injury; 
the dionaea mufcipula, which was lately brought over from the 
marfhes of America, prefents us with another curious inftance 
of vegetable irritability ; its leaves are armed with.fpines on 
their upper edge, and are fpread on the ground around the 
ftem ; when an infect creeps on any of them in its paflage to 
the flower or feed, the leaf fhuts up like a fteel rat-trap, and de- 
ftroys its enemy. See Botanic Garden, Part II. note on Silene. 
The various fecretions of vegetables, aS of odour, fruit, gum, 
tefin, wax, honey, feem brought about in the fame manner as ia 
the glands of animals : the taftelefs moifture of the earth is con- 
verted by the hop-plant into a bitter juice ; as by the caterpil- 
lar in the nutfliell the fweet kernel is converted into a bitter 
powder. While the power of abforption in the roots and barks 
®f vegetables is excited into action by the fluids applied to their 
mouths like the ladleals and lymphatics of animals. 
2. The individuals of the vegetable world may be considered 
as inferior or lefs perfect animals ; a tree is a congeries of many 
living buds, and in this refpect refembles the branches of coral- 
line, which are a congeries of a multitude of animals. Each of 
thefe buds of a tree has its proper leaves or petals for lungs, 
produces its viviparous or its oviparous offspring in buds or 
feeds ; has its own roots, which extending down the ftem of 
the tree are interwoven with the roots of the other buds, and 
form the bark, which is the only living part of the ftem, is an- 
nually renewed, and is fuperinduced upon the former bark, 
which then dies, and with its ftagnated juices gradually harden- 
Vol. I. L ing 74 
OF VEGETABLE 
Sect. XIII. 2. 
ing into wood forms the concentric circles, which we fee in 
blocks of timber. 
The following circumftances evince the individuality of the 
buds of trees. Firft, there are many trees, whole whole internal 
wood is perifhed, and yet the branches are vegete and healthy. 
Secondly, the fibres of the barks of trees are chiefly longitudinal, 
refembling roots, as is beautifully feen in thofe prepared barks, 
that were lately brought from Otaheite. Thirdly, in horizontal 
wounds of the bark of trees, the fibres of the upper lip are al- 
ways elongated downwards like roots, but thofe of the lower 
lip do not approach to meet them. Fourthly, if you wrap wet 
mofs around any joint of a vine, or cover it with moift earth, 
roots will fhoot out from it. Fifthly, by the inoculation or in- 
grafting of trees many fruits are produced from one ftem. 
Sixthly, a new tree is produced from a branch plucked from 
an old one, and fet in the ground. Whence it appears that the 
buds of deciduous trees are fo many annual plants, that the 
baik is a contexture of the caudexes of each individual bud ; 
which confifts of a leaf or plumula at top, of a radicle below, 
and of a caudex, which joins thefe together, and conftitutes the 
bark of'the tree, and that the internal wood is of no other ufe 
but to fupport them in the air, and that thus they refemble the 
animal world in their individuality. 
The irritability of plants, like that of animals, appears liable 
to be increafed or decreafed by habit; for thofe trees or fhrubs, 
which are brought from a colder climate to a warmer, put out 
their leaves and blofloms a fortnight fooner than the indigenous 
ones. 
Profeflbr Kalm, in his Travels in New York, obferves that 
the apple-trees brought from England bloflbm a fortnight foon- 
er than the native ones. In our country the fhrubs, that are 
brought a degree or two from the north, are obferved to flour- 
ifh better than thofe, which come from the fouth. The Sibe- 
rian barley and cabbage are faid to grow larger in this climate 
than the fimilar more fouthern vegetables. And our hoards of 
roots, as of potatoes and onions, germinate with lefs heat in 
fpring after they have been accuftomed to the winter's cold, 
than in autumn after the fummer's heat. 
II. The ftamens and piftils of flowers fliew evident marks of 
fenfibility, not only from many of the ftamens and fome piftils 
approaching towards each other at the feafon of impregnation, 
but from many of them clofing their petals and calyxes during 
the cold parts of the day. For this cannot be afcribed to irri- 
tation, becaufe cold means a defeft of the ftimulus of heat ; 
but as the want of accuftomed ftimuli produces pain, as in cold- 
nefs. Sect. XIII. 3. 
ANIMATION. 
75 
nefs, hunger, and thirft of animals, thefe motions of vegetables 
in doling up their flowers mull be afcribed to the difagreeable 
fenfation, and not to the irritation of cold. Others clofe up 
their leaves during darknefs, which, like the former, cannot be 
owing to irritation, as the irritating material is withdrawn. 
It may be objeded, that, when the petals and calyxes of flow- 
ers, and the leaves of fome vegetables, clofe in the night, this 
may be their natural ftate, like the doling of the eyelids in the 
fleep of animals; and that it Ihould thence be afcribed to the 
fufpenfion of volition, rather than to difagreeable fenfation. 
It may be anfwered, that in the fleep of animals the dofing of 
the eyelids may not be the natural ftate of the part, fince in the 
great inirritability and infenfibility attending fome fevers the pa- 
tients fleep with their eyes half-open, and in adual death the 
eyes do not clofe fpontaneoufly, and that hence the doling of 
the eyelids in fleep feems to be in confequence of our increafed 
internal fenfibility to light, or dull, or drynefs. 
And it is certain, that the abfence of the accuftomed quanti- 
ty of heat decreafes the action of animal fibres, as is evinced by 
the palenefs of the Ikin, when it is expofed to great cold; and 
the increafed addon of the fubcutaneous mufcles,as in fhudder- 
ing from cold, is certainly owing to the difagreeable fenfation 
confequent to the diminution of the accuftomed irritative mo- 
tions, as in Sect. XXXII. io. and Sed:. IV. 5. 
An excefs of moifture on fome parts of flowers and leaves 
may occafion a difagreeable fenfation, as when a drop of water 
gets down the windpipe into the lungs of animals, and may 
thus occafion them to clofe. 
The approach of the anthers in many flowers to the ftigmas, 
and of the piftils of fome flowers to the anthers, muft be afcri- 
bed to the paflion of love, and hence belongs to fenfation, not to 
irritation. 
III. That the vegetable world poiTefles fome degree of vol- 
untary powers, appears from their neceflity to fleep, which wc 
have fnewn in Sed. XVIII. to confift in the temporary abolition 
of voluntary power. This voluntary power feems to be exerted 
in the circular movement of the tendrils of vines, and other 
climbing vegetables ; or in the efforts to turn the upper furface 
of their leaves, or their flowers to the light. 
IV. The aflbeiations of fibrous motions are obfervable in the 
vegetable world, as well as in the animal. The divilions of the 
leaves of the fenfitive plant have been accuftomed to contrad at 
the fame time from the abfence of light; hence if by any other 
circumftance, as a flight ftroke or injury, one divifion is irrita- 
ted into contraction, the neighbouring ones contrad alfo, from 
their 76 
OF VEGETABLE 
Sect. XIII. 5. 1. 
their motions being aflbciated with thofe of the irritated part. 
So the various ftamina of the clafs of fyngenefia have been accuf- 
tomed to contract together in the evening, and thence if you 
ftimulate one of them with a pin, according to the experiment 
of M. Colvolo, they all contraCt from their acquired aflbciations. 
Which alfo (hows, that the number of male or female organs 
exifting in one flower does not deftroy the individuality of it; 
any more than the number of paps of a bitch or fow, or the 
double organ of a barn-door cock ; which is further evinced by 
the anthers and ftigmas of fome hermaphrodite flowers proba- 
bly receiving their nutriment from the fame honey-gland or 
nectary, and having their blood oxygenated by the fame corol, 
while in the plants of the clafles of monecia and diecia the male 
and female organs of reproduction belong to different vegetable 
beings. 
To evince that the collapfing of the fenfitive plant is not ow- 
ing to any mechanical vibrations propagated along the whole 
branch, when a Angle leaf is (truck with the finger, a leaf of it 
was flit with fharp feiflars, and fome feconds of time pafled be- 
fore the plant feemed fenfible of the injury ; and then the whole 
branch collapfed as far as the principal item : this experiment 
was repeated feveral times with the leaft poflible impulfe to the 
plant. 
V. i. For the numerous circumftances in which vegetable 
buds are analogous to animals, the reader is referred to the ad- 
ditional notes at the end of the Botanic Garden, Part I. It is 
there (hewn, that the roots of vegetables refemble the laCteal fyf- 
tem of animals ; the fap-veffels in the early fpring, before their 
leaves expand, are analogous to the placental veflels of the foe- 
tus ; that the leaves of land-plants refemble lungs, and thofe of 
aquatic plants the gills of fifh ; that there are other fyltems of 
veflels refembling the vena portarum of quadrupeds, or the aor- 
ta of fifh ; that the digeftive power of vegetables is fimilar to 
that of animals, converting the fluids, which they abforb, into 
fugar ; that their feeds refemble the eggs of animals, and their 
buds and bulbs their viviparous offspring. And, laftly, that 
the anthers and ftigmas are real animals, attached indeed to 
their parent tree like polypi or coral infeCts, but capable of fpon- 
taneous motion; that they are affected with the paflion of 
love, and furnifhed with powers of reproducing their fpecies, 
and are fed with honey like the moths and butterflies, which 
plunder their neCtaries. See Botanic Garden, Part I. add. note 
XXXIX. 
The male flowers of vallifneria approach ftill nearer to appar- 
ent animality, as they detach themfclves from the parent plant, 
and Sect. XIII. 5. 2. 
ANIMATION. 
77 
and float on the furface of the water to the female ones. Botan- 
ic Garden, Part II. Art. Vallifneria. Other flowers of the 
clafles of monecia and diecia, and polygamia, difcharge the fe- 
cundating farina, which floating in the air is carried to the ftig- 
ma of the female flowers, and that at confiderable diftances. 
Can this be effected by any fpecific attraction ? or, like the dif- 
fufion of the odorous particles of flowers, is it left to the cur- 
rents of winds, and the accidental mifcarriages of it counteract- 
ed by the quantity of its production ? 
2. This leads us to a curious inquiry, whether vegetables have 
ideas of external things ? As all our ideas are originally received 
by otlr fenfes, the queftion may be changed to, whether vegeta- 
bles poflefs any organs of fenfe ? Certain it is, that they poflefs 
a fenfe of heat and cold, another of moifture and drynefs, and 
another of light and darknefs ; for they clofe their petals occa- 
fionally from the prefence of cold, moiiture, or darknefs. And 
it has been already (hewn, that thefe actions cannot be perform- 
ed Amply from irritation, becaufe cold and darknefs are negative 
quantities, and on that account fenfation or volition are implied, 
and in confequence a fenforium or union of their nerves. So 
when we go into the light, we contraCi: the iris ; not from any 
ftimulus of the light on the fine mufcles of the iris, but from its 
motions being aflbciated with the fenfation of too much light on 
the retina : which could not take place without a fenforium or 
centre of union of the nerves of the iris with thofe of vifion. 
See Botanic Garden, Part I. Canto 3.1. 440 note. 
Befides thefe organs of fenfe, which diftinguifti cold, moifture, 
and darknefs, the leaves of mimofa, and of dionsea, and of dro- 
fera, and the ftamens of many flowers, as of the berberry, and 
the numerous clafs of fyngenefia, are fenfible to mechanic im- 
paCt, that is, they poflefs a fenfe of touch, as well as a common 
fenforium; by the medium of which their mufcles are excited 
into aCtion. Laftly, in many flowers the anthers, when mature, 
approach the ftigma, in others the female organ approaches to 
the male. In a plant of collinfonia, a branch of which is now 
before me, the two yellow ftamens are about three eights of an 
inch high, and diverge from each other at an angle of about fif- 
teen degrees, the purple ftyle is half an inch high, and in fome 
flowers is now applied to the ftamen on the right hand, and in 
others to that of the left; and will, I fuppofe, change place to- 
morrow in thofe, where the anthers have not yet effufed 
their powder. 
I alk, by what means are the anthers in many flowers, and 
ftigmas in other flowers, direCted to find their paramours ? 
How do either of them know, that the other exifts in their vi- 
cinity ? 78 
OF VEGETABLE, &e. 
Sect. XIII. 5. 2. 
cinity ? Is this curious kind of ftorge produced by mechanic 
attra&ion, or by the fenfation of love ? The latter opinion is 
fupported by the ftrongeft analogy, becaufe a reproduction of 
the fpecies is the confequence; and then another organ of fenfe 
muft be wanted to direCt thefe vegetable amourettes to find 
each other, one probably analogous to our fenfe of fmell, which 
in the animal world direCts the new-born infant to its fource of 
nourilhment, and they may thus polfefs a faculty of perceiving 
as well as of producing odours. 
Thus, befides a kind of tafte at the extremities of their roots, 
fimilar to that of the extremities of our laCleal veflels, for the 
purpofe of felcQing their proper food: and befides different 
kinds of irritability refiding in the various glands, which fepa- 
rate honey, wax, refin, and other juices from their blood ; vege- 
table life feems to poflefs an organ of fenfe to diftinguilh the va- 
riations of heat, another to diftinguilh the varying degrees of 
moifture, another of light, another of touch, and probably anoth- 
er analogous to our fenfe of fmell. To thefe muft be added the 
indubitable evidence of their paflion of love, and I think we 
may truly conclude, that they are furnilhed with a common 
fenforium belonging to each bud, and that they muft occafion- 
ally repeat thofe perceptions either in their dreams or waking 
hours, and confequently poflefs ideas of fo many of the proper- 
ties of the external world, and of their own exiftence. 
SECT. Sect. XTV. i. 
PRODUCTION, &c. 
79 
SECT. XIV. 
OF THE PRODUCTION OF IDEAS. 
I. Of material and immaterial beings. Doctrine of St. Paul. II. 
I. Of the fenfe of touch. Offolidity. 2. Of figure. Motion. 
Time. Place. Space. Number. 3. Of the penetrability of 
matter. 4. Spirit of animation poffejfes folidity* figure* vifibility* 
i^c. Of [pirits and angels. $. The exfience of external things. 
III. Of vifton. IV. Of hearing. V. Offmell and tajle. VI. 
Of the organ of fenfe by which we perceive heat and cold* not by 
the fenfe of touch. VII. Of the fenfe of extenfon* the whole of the 
locomotive mufcles may be conftdered as one organ of fenfe. VIII. 
Of the fenfes of hunger* thirfl* want offrejh air *ftickling children* 
and luji. IX. Of many other organs of fenfe belonging to the 
glands. Of painful fenfations from the excefs of light* prejfure* 
beat* itching* caujlics* and electricity. 
I. Philosophers have been much perplexed to underftand, 
in what manner we become acquainted with the external world ; 
infomuch that Dr. Berkeley even doubted its exigence, from 
having obferved (as he thought) that none of our ideas refemble 
their correfpondent objects. Mr. Hume aflerts, that our belief 
depends on the greater diftinCtnefs or energy of our ideas from 
perception; and Mr. Reid has lately contended, that our belief 
of external objects is an innate principle neceflarily joined with 
our perceptions. 
So true is the obfervation of the famous Malbranch, « that 
our fenfes are not given us to difeover the eflences of things, 
but to acquaint us with the means of preferving our exiftence," 
(L. I. ch. v.) a melancholy reflection to philofophers ! 
Some philofophers have divided all created beings into 
material and immaterial: the former including all that part 
of being, which obeys the mechanic laws of action and reaction, 
but which can begin no motion of itfelf *, the other is the caufe 
of all motion, and is either termed the power of gravity, or of 
fpecific attraction, or the fpirit of animation. This immaterial 
agent is fuppofed to exift in or with matter, but to be quite dif- 
tinCt from it, and to be equally capable of exigence, after the 
matter, which now poflefles it, is decompofed. 
Nor is this theory ill fupported by analogy, fince heat, elec- 
tricity, and magnetifm, can be given to or taken from a piece 
of iron ; and muft therefore exilt, whether feparated from the 
metal, or combined with it. From a parity of reafoning, the 
fpirit 80 
PRODUCTION 
Sect. XIV. 2. i. 
fpirit of animation would appear to be capable of exifting as well 
feparately from the body as with it. 
I beg to be underftood, that I do not wifh to difpute about 
words, and am ready to allow, that the powers of gravity, fpe- 
cific attraction, electricity, magnetifm, and even the fpirit of 
animation, may confift of matter of a finer kind ; and to believe, 
with St. Paul and Malbranch, that the ultimate caufe only of all 
motion is immaterial, that is God. St. Paul fays, " in him we 
live and move, and have our being f and, in the 15 th chapter 
to the Corinthians, diftinguifhes between the pfyehe or living 
fpirit, and the pneuma or reviving fpirit. By the words fpirit 
of animation or fenforial power, I mean only that animal life, 
which mankind pofiefles in common with brutes, and in fome 
degree eve-n with vegetables, and leave the confideration of the 
immortal part of us, which is the object of religion, to thofe 
who treat of revelation. 
II. I. Of the Senfe of Touch. 
The firft ideas we become acquainted with, are thofe of the 
fenfe of touch ; for the foetus muft experience fome varieties of 
agitation, and exert fome mufcular a&ion, in the womb ; and 
may with great probability be fuppofed thus to gain fome ideas 
of its own figure, of that of the uterus, and of the tenacity of 
the fluid, that furrounds it, (as appears from the facts mention- 
ed in the fucceeding Se&ion upon Inftindt.) 
Many of the organs of fenfe are confined to a fmall part of 
the body, as the noltrils, ear, or eye, whilft: the fenfe of touch is 
diffufed over the whole ikin, but exifts with a more exquifite 
degree of delicacy at the extremities of the fingers and thumbs, 
and in the lips. The fenfe of touch is thus very commodioufly 
difpofed for the purpofe of encompafling fmaller bodies, and for 
adapting itfelf to the inequalities of larger ones. The figure of 
fmall bodies feems to be learnt by children by their lips as much 
as by their fingers ; on which account they put every new ob- 
jedl to their mouths, when they are fatiated with food, as well 
as when they are hungry. And puppies feem to learn their 
ideas of figure principally by the lips in their mode of play. 
We acquire our tangible ideas of objects either by the Ample 
preflure of this organ of touch againft a folid body, or by 
moving our organ of touch along the furface of it. In the former 
cafe we learn the length and breadth of the object by the quan- 
tity of our organ of touch, that is imprefled by it: in the latter 
cafe we learn the length and breadth of objects by the continu- 
ance of their preffure on our moving organ of touch. 
It Sect. XIV. 2. 2. 
OF IDEAS. 
81 
It is hence, that we are very flow in acquiring our tangible 
ideas, and very flow in recolledting them ; for if I now think of 
the tangible idea of a cube, that is, if I think of its figure, and 
of the folidity of every part of that figure, I muft conceive my- 
felf as palling my fingers over it, and feem in fome meafure to 
feel the idea, as I formerly did the impreflion, at the ends of 
them, and am thus very flow in diftinCtly recollecting it. 
When a body comprefles any part of our fenfe of touch, what 
happens ? Firft, this part of our fenforium undergoes a mechan- 
ical compreflion, which is termed a ftimulus ; fecondly, an idea, 
or contraction of a part of the organ of fenfe is excited ; third- 
ly, a motion of the central parts, or of the whole fenforium, 
which is termed fenfation, is produced; and thefe three confti- 
tute the perception of folidity. 
2. Of Figure, Motion, Time, Place, Space, Number. 
No one will deny, that the medulla of the brain and nerves 
has a certain figure; which, as it is diffufed through nearly the 
whole of the body, mult have nearly the figure of that body. 
Now it follows, that the fpirit of animation, or living principle, 
as it occupies this medulla, and no other part, (which is evinced 
by a great variety of cruel experiments on living animals,) it 
follows, that this fpirit of animation has alfo the fame figure as 
the medulla above defcribed. I appeal to common fenfc ! the 
fpirit of animation acts, Where does it a£l ? It a£ls wherever 
there is the medulla above mentioned ; and that whether the 
limb is yet joined to a living animal, or whether it be recently 
detached from it; as the heart of a viper or frog will lenew its 
contractions, when pricked with a pin, for many minutes of time 
after its exfedion from the body.-Does it act any where elfe I 
-No ; then it certainly exifts. in this part of fpace, and no 
where elfe; that is, it hath figure ; namely, the figure of the 
nervous fyftem, which is nearly the figure of the body. When 
the idea of folidity is excited, as above explained, a part of the 
extenfive organ of touch is comprefled by fome external body* 
and this part of the fenforium fo comprefied exactly refembles 
figure the figure of the body that comprclfed it. Hence, when 
we acquire the idea of folidity, we acquire at the fame time the 
idea of figure ; and this idea of figure, or motion of a part of 
the organ of touch, exaftly refembles in its figure the figure of 
the body that occafions it ; and thus exactly acquaints us with 
this property of the external world. 
Now, as the whole univerfe with all its parts poflefles a cer- 
tain form or figure, if any part of it moves, that form or figure 
Vol. I. M ' of 82 
PRODUCTION 
Sect. XIV. 2. 2. 
of the whole is varied : hence, as motion is no other than a per- 
petual variation of figure, our idea of motion is alfo a real re- 
femblance of the motion that produced it. 
It may be faid in objection to this definition of motion, that 
an ivory globe may revolve on its axis, and that here will be a 
motion without change of figure. But the figure of the parti- 
cle x on one fide of this globe is not the fame figure as the figure 
of y on the other fide, any more than the particles themfelves 
are the fame, though they are fimilar figures ; and hence they 
cannot change place with each other without difturbing or 
changing the figure of the whole. 
Our idea of time is from the fame fource, but is more ab- 
ftrafled, as it includes only the comparative velocities of thefe 
variations of figure; hence if it be afked, How long was this 
book in printing ? it may be anfwered, Whilft the fun was 
palling through Aries. 
Our idea of place includes only the figure of a group of 
bodies, not the figures of the bodies themfelves. If it be alked 
where is Nottinghamfhire, the anfwer is, it is furroundcd by 
Derbyshire, Lincolnfhire, and Leicelterlhire ; hence place is our 
idea of the figure of one body furrounded by the figures of other 
bodies. 
The idea of space is a more abftra&ed idea of place exclu- 
ding the group of bodies. 
The idea of number includes only the particular arrange- 
ments, or diftributions of a group of bodies, and is therefore on- 
ly a more abftra&ed idea of the parts of the figure of the group 
of bodies; thus when I fay England is divided into forty coun- 
ties, I only fpeak of certain divisions of its figure. 
Hence arii'es the certainty of the mathematical fciences, as 
they explain thefe properties of bodies, which are exactly re- 
feinbled by our ideas of them, whilft we arc obliged to collect 
almolt all our other knowledge from experiment; that is, by 
obferving the effects exerted by one body upon another. 
I feel myfelf much obliged by the accurate attention given to 
the firft volume of Zoonomia, and by the ingenious criticifms 
bellowed on it, by the learned writers of that article both in 
the Analytical and Englifh Reviews. Some circumftances, in 
which their fentiments do not accord with thofe exprefled in the 
work, I intend to reconfider, and to explain further at fome fu- 
ture time. One thing, in which both thefe gentlemen feenr to 
diflent from me, I fhall now mention, it is concerning the man- 
ner, in which we acquire the idea of figure ; a circumllance of 
great importance in the knowledge of our intellect, as it fhews 
the caufe of the accuracy of our ideas of motion, time, fpace, 
. number, Sect. XIV. 2. 2. 
OF IDEAS. 
83 
number, and of the mathematical fciences, which are concerned 
in the menfurations or proportions of figure. 
This I imagine may have in part arifen from the prepoflef- 
fion, which has almoft univerfally prevailed, that ideas are im- 
material beings, and therefore poffefs no properties in common 
with folid matter. Which I fuppofe to be a fanciful hypothefis, 
like the ftories of ghofts and apparitions, which have fo long 
amufed, and ftill amufe the credulous without any foundation 
in nature. 
The exiftence of our own bodies, and of their folidity, and of 
their figure, and of their motions, is taken for granted in my 
account of ideas; becaufe the ideas themfelves are believed to 
confift of motions or configurations of folid fibres ; and the 
queftion now propofed is, how we become acquainted with the 
figures of bodies external to our organs of fenfe ? Which I can 
only repeat from what is mentioned in Se6l. XIV. 2. 2. that 
if part of an organ of fenfe be ftimulated into action, as of the 
fenfe of touch, that part fo ftimulated into action muft poflefs 
figure, which mult be fimilar to the figure of the body, which 
ftimulates it. 
Another previous prepofleflion of the mind, which may have 
rendered the manner of our acquiring the knowledge of figure 
lefs intelligible, may have arifen from the common opinion of 
the perceiving faculty refiding in the head ; whereas our daily 
experience fhews, that our perception (which confifls of an idea, 
and of the pleafure or pain it occalions) exifts principally in the 
organ of fenfe, which is ftimulated into action ; as every one, 
who burns his finger in the candle, muft be bold to deny. 
When an ivory triangle is preffed on the palm of the hand, 
the figure of the furface of the part of the organ of touch thus 
comprefled is a triangle, refemblfhg in figure the figure of the 
external body, which compreffes it. The action of the ftimu- 
lated fibres, which conftitute the idea of hardnefs'and of figure, 
remains in this part of the fenforium, which forms the fenfe of 
touch; but the fenforial motion, which conflitetes pleafure or 
pain, and which is excited in confequence of thefe fibrous mo- 
tions of the organ of fenfe, is propagated to the central parts of 
the fenforium, or to the whole of it; though this generally oc- 
curs in lefs degree of energy, than it exifts in the ftimulated or- 
gan of fenfe; as in the inftance above mentioned of burning a 
finger in the candle. 
Some, who have efpoufed the doctrine of the immateriality of 
ideas, have ferioufly doubted the exiftence of a material world, 
with which only our fenfes acquaint us ; and yet have affented 
to the exiftence of fpirit, with which our fenfes cannot acquaint 
us j 84 
PRODUCTION 
Sect. XIV. 2. 3. 
us; and have finally allowed, that all our knowledge is derived 
through the medium of our fenfes 1 They forget, that if the 
fpirit of animation had no properties in common with matter, it 
could neither afteeft nor be affefled by the material body- But 
the knowledge of our own material exiftence being granted, 
which I fufpect few rational perfons will ferioufly deny, the ex- 
iftence of a material external world follows in courfe; as our 
perceptions, when we are awake and not infane, are diftinguifli- 
ed from thofe excited by fenfation, as in our dreams, and from 
thofe excited by volition or by aflbeiation, as in infanity and 
reverie, by the power we have of comparing the prefent percep- 
tions of one fenfe with thofe of another, as explained in Se€L 
XIV. 2. 5. And alio by comparing the tribes of ideas, which 
the fymbols of pictures, or of languages, fuggeft to us, by intui- 
tive analogy with our previous experience, that is, with the com- 
mon courfe of nature. See Clafs III. 2. 2. 3. on Credulity. 
3. Of the Penetrability of Matter. 
The impoffibility of two bodies exifting together in the fame 
fpace'Cannot be deduced from our idea of folidity, or of figure. 
As foon as we perceive the motions of objects that furround us, 
and learn that we poffefs a power to move our own bodies, we 
experience, that thofe objects, which excite in us the idea of 
folidity and of figure, oppofe this voluntary movement of our 
own organs ; as whilft I endeavour to comprefs between my 
hands an ivory ball into a fpheroid. And we are hence taught 
by experience, that our own body and thofe, which we touch, 
cannot exift in the fame part of fpace. 
But this by no means demonftrates, that no two bodies can 
exift together in the fame part of fpace. Galiheo in the preface 
to his works feems to be of opinion, that matter is not impene- 
trable ; Mr. Mitchel, and Mr. Bofcowich in his Theoria Philof. 
Natur. have efpoufed this hypothefis : which has been lately 
publifhed by Dr. Prieftlev, to whom the world is much indebted 
for fo many important difcoveries in fcience. (Hift. of Light 
and Colours, p. 391-) The uninterrupted paflage of light 
through tranfparent bodies, of the electric aether through metal- 
lic and aqueous bodies, and of the magnetic effluvia through all 
bodies, would feem to give fome probability to this opinion. 
Hence it appears, that beings may exift without poflefling the 
property of folidity, as well as they can exift without poflefflng 
the properties, which excite our imell or tafte, and can thence 
occupy fpace without detruding other bodies from it; but we 
cannot become acquainted with fuch beings by our fenfe of 
touch. Sect. XIV. 2. 4. 
OF IDEAS. 
85 
touch, any more than we can with odours or flavours without 
our fenfes of fmell and tafte. 
But that any being can exift without exifting in fpace, is to 
my ideas utterly incomprehenfible. My appeal is to common 
fenfe. To be implies a when and a where ; the one is com- 
paring it with the motions of other beings, and the other with 
their fituations. 
If there was but one object, as the whole creation may be 
confidered as one object, then I cannot afk where it exifts ? 
for there are no other objects to compare its fituation with. 
Hence if any one denies, that a being exifts in fpace, he denies, 
that there are any other beings but that one ; for to anfwer the 
queftion, « Where does it exift ?" is only to mention the fitu- 
ation of the objects that furround it. 
In the fame manner if it be afked-a When does a being 
exift ?" The anfwer only fpecifies the fucceflive motions either 
of itfelf, or of other bodies ; hence to fay, a body exifts not in 
time, is to fay, that there is, or was, no motion in the world. 
4- Of the Spirit of Animation. 
But though there may exift beings in the univerfe, that have 
not the property of folidity ; that is, which can poflcfs any part 
of fpace, at the fame time that it is occupied by other bodies ; 
yet there may be other beings, that can affume this property of 
folidity, or difrobe themfelves of it occafionally, as we are taught 
of fpirits, and of angels ; and it would feem, that the spirit 
of animation muft be endued with this property, otherwife 
how could it occafionally give motion to the limbs of animals ? 
-or be itfelf flimulated into motion by the obtrufions of fur- 
rounding bodies, as of light, or odour ? 
If the fpirit of animation was always neceflarily penetrable, 
it could not influence or be influenced by the folidity of com- 
mon matter; they would exift together, but could not detrude 
each other from the part of fpace, where they exift ; that is, 
they could not communicate motion to each other. No two 
things can influence or affect each other which have not fome prop- 
erty common to both of them ; for to influence or a fie cl another 
body is to give or communicate fome property to it, that it had 
not before ; but how can one body give that to another; which 
it does not poflefs itfelf t-The words imply, that they muft 
agree in having the power or faculty of poflelhng fome common 
property. Thus if one body removes another from the part of 
fpace, that it poflefles, it muft have the power of occupying 
that fpace itfelf: and if Oue body communicates heat or motion 
to 86 
PRODUCTION 
Sect. XIV. 2. 
to another, it follows, that they have alike the property of pof- 
feffing heat or motion. 
Hence the fpirit of animation, at the time it communicates 
or receives motion from folid bodies, muft itfelf poflcfs fome 
property of folidity. And in confequence at the time it re- 
ceives other kinds of motion from light, it muft poflefs that 
property, which light poflefles, to communicate that kind of 
motion ; and for which no language has a name, unlefs it may 
be termed Vifibility. And at the time it is ftimulated into oth- 
er kinds of animal motion by the particles of fapid and odorous 
bodies affebting the fenfes of tafte and fmell, it muft refcmble 
thefe particles of flavour, and of odour, in pofleffing fome fim- 
ilar or correfpondent property ; and for which language has no 
name, unlefs we may ufe the words Saporofity and Odorofity 
for thofe common properties, which are poflefled by our organs 
of tafte and fmell, and by the particles of fapid and odorous 
bodies *, as the words Tangibility and Audibility may exprefs 
the common property poflefled by our organs of touch, and of 
hearing, and by the folid bodies, or their vibrations, which af- 
fect thofe organs. 
5. Finally, though the figures of bodies are in truth refem- 
hled by the figure of the part of the organ of touch, which is 
ftimulated into motion ; and that organ refembles the folid 
body, which ftimulates it, in its property of folidity ; and 
though the fenfe of hearing refembles the vibrations of external 
bodies in its capability of being ftimulated into motion by thofe 
vibrations ; and though our other organs of fenfe refemble the 
bodies, that ftimulate them, in their capability of being ftimu- 
lated by them ; and we hence become acquainted with thefe 
properties of the external world ; yet as we can repeat all thefe 
motions of our organs of fenfe by the efforts of volition, or in 
confequence of the fenfation of pleafure or pain, or by their af- 
fociation with other fibrous motions, as happens in our reveries 
or in fleep, there would ftill appear to be fome difficulty in 
demonftrating the exiftcnce of any thing external to us. 
In our dreams we cannot determine this circumftance, be- 
caufe our power of volition is fufpended, and the ftimuli of ex- 
ternal objects are excluded ; but in our waking hours we can 
compare our ideas belonging to one fenfe with thofe belonging to 
another, and can thus diftinguiffi the ideas occafioned by irrita- 
tion from thofe excited by fenfation, volition, or aflbciation. 
Thus if the idea of the fweetnefs of fugar fhould be excited in 
our dreams, the whitenefs and hardnefs of it occur at the fame 
time by aflbciation ; and we believe a material lump of fugar 
prefeiit before us. But if, in our waking hours, the idea of the 
fweetnefs Sect. XIV. 3. 
OF IDEAS. 
87 
fweetnefs of fugar occurs to us, the ftimuli of furrounding ob- 
jefts, as the edge of the table, on which we prefs, or green 
colour of the grafs, on which we tread, prevent the other ideas 
of the hardnefs and whitenefs of the fugar from being excited 
by affociation. Or if they (liould occur, we voluntarily com- 
pare them with the irritative ideas of the table or grafs above 
mentioned, and detect their fallacy. Wc can thus diitinguifli 
the ideas caufed by the ftimuli of external objects from thofe, 
which are introduced by affociation, fenfation, or volition ; and 
during our waking hours can thus acquire a knowledge of the 
external world. Which neverthelefs we cannot do in our 
dreams, becaufe we have neither perceptions of external bodies, 
nor the power of volition to enable us to compare them with 
the ideas of imagination. 
III. OfVijlon. 
Our eyes obferve a difference of colour, or of (hade, in the 
prominences and depreflions of objects, and that thofe (hades 
uniformly vary, when the fenfe of touch obferves any variation. 
Hence when the retina becomes ftimulated by colours or (hades 
of light in a certain form, as in a circular fpot ; we know by 
experience, that this is a fign, that a tangible body is before us ; 
and that its figure is refembled by the miniature figure of the 
part of the organ of vifion, that is thus ftimulated. 
Here whilft the ftimulated part of the retina refembles exact- 
ly the vifible figure of the whole in miniature, the various kinds 
of ftimuli from different colours -mark the vifible figures of the 
minuter parts 5 and by habit we inftantly recall the tangible 
figures. 
Thus when a tree is the objeft of fight, a part of the retina 
refembling a flat branching figure is ftimulated by various (hades 
of colours ; but it is by fuggeftion, that the gibbofity of the 
tree, and the mofs, that fringes its trunk, appear before us. 
Thefe are ideas of fuggeftion, which we feel or attend to, affo- 
ciated with the motions of the retina, or irritative ideas, which 
we do not attend to. 
So that though our vifible ideas refemble in miniature the 
outline of the figure of coloured bodies, in other refpe&s they 
ferve only as a language, which by acquired aflbciations intro- 
duce the tangible ideas of bodies. Hence it is, that this fenfe 
is fo readily deceived by the art of the painter to our amufe- 
ment and inftru&ion. The reader will find much very curious 
knowledge on this fubjeft in Bifhop Berkeley's Effay on Vifion, 
a work of great ingenuity. 
The 88 
PRODUCTION 
Sect. XIV. 4. 
The immediate object however of the fenfe of vifion is light; 
this fluid, though its velocity is fo great, appears to have no per- 
ceptible mechanical impulfe, as was mentioned in the third 
Section, but feems to flimulate the retina into animal motion 
by its tranfmiIlion through this part of the fenforium : for 
though the eyes of cats or other animals appear luminous in ob- 
fcure places ; yet it is probable, that none of the light, which 
falls on the retina, is reflected from it, but adheres to or enters 
into combination with the choroide coat behind it. 
The combination of the particles of light with opaque bodies, 
and therefore with the choroide coat of the eye, is evinced from 
the heat which is given out, as in other chemical combinations. 
For the fun-beams communicate no heat in their pafl'age through 
tranfparent bodies, with which they do not combine, as the air 
continues cool even in the focus of the largeft burning-glafles, 
which in a moment vitrifies a particle of opaque matter. 
IV. Of the Organ cf Hearing. 
It is generally believed, that the tympanum of the ear vi- 
brates mechanically, when expofcd to audible founds, like the 
firings of one mufical inftrument, when the fame notes are 
ftruck upon another. Nor is this opinion improbable, as the 
mufcles and cartilages of the larinx are employed in producing 
variety of tones by mechanical vibration : fo the mufcles and 
bones of the ear feem adapted to increafe or diminifh the ten- 
fion of the tympanum for the purpofes of fimilar mechanical 
vibrations. 
But it appears from difle&ion, that the tympanum is not the 
immediate organ of hearing, but that, like the humours and cor- 
nea of the eye, it is only of ufe to prepare the object for the 
immediate organ. For the portio mollis of the auditory nerve 
is not fpread upon the tympanum, but upon the veltibulum, and 
cochlea, and femi-circular canals of the car ; while between the 
tympanum and the expanfion of the auditory nerve the cavity is 
faid by Dr. Cotunnus and Dr. Mechel to be filled with water ; 
as they had frequently obferved by freezing the heads of dead 
animals before they diiTecled them ; and water being a more 
denfe fluid than air is much better adapted to the propagation 
of vibrations. We may add, that even the external opening of 
the ear is not abfolutely neceflary for the perception of found : 
for fome people, who from thefe defects would have been com- 
pletely deaf, have diftinguifhed acute or grave founds by the tre- 
mours of a flick held between their teeth propagated along the 
bones ox the head, (Haller. Phyf. T. V. p. 295). 
Hence Sect. XIV. 5. 
OF IDEAS. 
89 
Hence it appears, that the immediate organ of hearing is 
not afledted by the particles of the air themfelves, but is ftimu- 
lated into animal motion by the vibrations of them. And it is 
probable from the loofe bones, which are found in the heads of 
fome fifties, that the vibrations of water are fenfible to the in- 
habitants of that element by a fimilar organ. 
The motions of the atmofphere, which we become acquainted 
with by the fenfe of touch, are combined with its folidity, 
weight, or vis inertite ; whereas thofe, ' that are perceived by 
this organ, depend alone on its elafticity. But though the vi- 
bration of the air is the immediate objedl of the fenfe of hear- 
ing, yet the ideas, we receive by this fenfe, like thofe received 
from light, are only as a language, which by acquired aflbeia- 
tions acquaints us with thofe motions of tangible bodies, which 
depend on their elafticity ; and which we had before learned 
by our fenfe of touch. 
V. Of Smell and of Tafte. 
The objects of fmell are diflblved in the fluid atmofphere, 
and thofe of tafte in the faliva, or other aqueous fluid, for the 
better diffufing them on their refpedtive organs, which feem to 
be ftimulated into animal motion perhaps by the chemical af- 
finities of thefe particles, which conftitute the fapidity and odo- 
rofity of bodies, with the nerves of fenfe, which perceive therm 
Mr. Volta has lately obferved a curious circumftance relative 
to our fenfe of tafle. If a bit of clean lead and a bit of clean 
filver be feparately applied to the tongue and palate no tafte is 
perceived ; but by applying them in contact in refpect to the 
parts out of the mouth, and nearly fo in refpedl to the parts, 
which are immediately applied to the tongue and palate, a fa- 
line or acidulous tafte is perceived, as of a fluid like a ftream of 
electricity palling from one of them to the other. This new 
application of the fenfe of tafte deferves further inveftigation, 
as it may acquaint us with new properties of matter. 
From the experiments above mentioned of Galvani, Volta, 
Fowler, and others, it appears, that a plate of zinc and a plate of 
filver have greater eflcCt than lead and filver. If one edge of a 
plate of filver about the fize of half a crown-piece be placed up- 
on the tongue, and one edge of a plate of zinc about the fame 
fize beneath the tongue, and if their oppofite edges are then 
brought into contaCf before the point of the tongue, a tafte is 
perceived at the moment of their coming into contact ; fecond- 
ly, if one of the above plates be put between the upper lip and 
the gum of the fore-teeth, and the other be placed under the 
Vol. I. N tongue. 90 
PRODUCTION 
Sect. XIV. 6. 
tongue, and their exterior edges be then brought into contact in 
a darkifli room, a flafh of light is perceived in the eyes. 
Thefe efleCts I imagine only (hew the fenfibility of our nerves 
of fenfe to very fmall quantities of the eleCtric fluid, as it pafles 
through them ; for I fuppofe thefe fenfations are occafioned by 
flight electric (hocks produced in the following manner. By 
the experiments publifhed by Mr. Bennet, with his ingenious 
doubler of electricity, which is the greatefl difeovery made in 
that fcience fince the coated jar, and the eduCtion of lightning 
from the fkies, it appears that zinc was always found minus, 
and filver was always found plus, when both of them were in 
their feparate ftate. Hence, when they are placed in the man- 
ner above defcribcd, as foon as their exterior edges come near- 
ly into contaCt, fo near as to have an extremely thin plate of air 
between them, that plate of air becomes charged in the fame 
manner as a plate of coated glafs ; and is at the fame inftant 
difeharged through the nerves of tafle or of fight, and gives the 
fenfations, as above defcribed, of light or of faporofity ; and on- 
ly (hews the great fenfibility of thefe organs of fenfe to the ftim- 
ulus of the eledric fluid in fuddenly pafling through them. 
VI. Of the Safe of Heat. 
There are many experiments in chemical writers, that evince 
the exiftence of heat as a fluid element, which covers and per- 
vades all bodies, and is attracted by the folutions of fome of 
them, and is detruded from the combination of others. Thus 
from the combinations of metals with acids, and from thofe 
combinations of animal fluids, which are termed fecretions, this 
fluid matter of heat is given out amongft the neighbouring bod- 
ies ; and in the folutions of faits in water, or of water in air, it 
is abforbed from the bodies, that furround them ; whilft in its 
facility in pafling through metallic bodies, and its difficulty in 
pervading refins and glafs, it refembles the properties of the 
electric aura ; and is like that excited by friction, and feems 
like that to gravitate amongft other bodies in its uncombined 
Hate, and to find its equilibrium. 
There is no circumitance of more confequence in the animal 
economy than a due proportion of this fluid of heat ; for the 
digeflion of our nutriment in the ftomach and bowels, and the 
proper qualities of all our fecreted fluids, as they are produced 
or prepared partly by animal and partly by chemical precedes, 
depend much on the quantity of heat ; the excefs of which, or 
its deficiency, alike gives us pain, and induces us to avoid the 
circumftances that occafion them. And in this the percep- 
, . ' tion Sect. XIV/6. 
OF IDEAS. 
91 
tion of heat effentially differs from the perceptions of the fenfe 
of touch, as we receive pain from too great preffure of foiid 
bodies, but none from the abfence of it. It is hence probable, 
that nature has provided us with a fet of nerves for the percep- 
tion of this fluid, which anatomifts have not yet attended to. 
There may be fome difficulty in the proof of this affertion 5 
if we look at a hot fire, we experience no pain of the optic 
nerve, though the heat along with the light muft be concentra- 
ted upon it. Nor does warm water or warm oil poured into 
the ear give pain to the organ of hearing ; and hence as thefe 
organs of fenfe do not perceive fmall exceffes or deficiencies of 
heat ; and as heat has no greater analogy to the folidity or to 
the figures of bodies, than it has to their colours or vibrations ; 
there feems no fufficient reafon for our afcribing the perception 
of heat and cold to the fenfe of touch; to which it has gener- 
ally been attributed, either bccaufe it is diffufed beneath the 
whole Ikin like the fenfe of touch, or owing to the inaccuracy of 
our obfervations, or the defeat of our languages. 
There is another circumftance would induce us to believe, 
that the perceptions of heat and cold do not belong to the or- 
gan of touch ; fince the teeth, which are the leaft adapted for 
the perceptions of folidity of figure, are the moft fenfible to heat or 
cold ; whence we are forewarned from fwallowing thofe mate- 
rials, whofe degree of coldnefs or of heat would injure our itom- 
achs. 
The following is an extract from a letter of Dr. R. W. Dar- 
win, of Shrewfbury, when he was a ftudent at Edinburgh. " I 
made an experiment yefterday in our hofpital, which much fa- 
vours your opinion, that the fenfation of heat and of touch de- 
pend on different fets of nerves. A man who had lately recov- 
ered from a fever, and was ftill weak, was feized with violent ' 
cramps in his legs and feet ; which were removed by opiates, 
except that one of his feet remained infenfible. Mr. Ewart 
pricked him with a pin in five or fix places, and the patient de- 
clared he did not feel it in the leaft, nor was he fenfible of a very 
fmart pinch. I then held a red-hot poker at fome diftance, and 
brought it gradually nearer till it came within three inches, 
when he afferted that he felt it quite diftindlly. I fuppofe fome 
violent irritation on the nerves of touch had caufed the cramps, 
and had left them paralytic ; while the nerves of heat, having 
fuffered no increafed ftimulus, retained their irritability." 
Add to this, that the lungs, though eafily ftimulated into in- 
flammation, are not fenfible to heat. See Clafs III. 1, 1, 10. 
VIL Of 92 
PRODUCTION1 
Sect. XIV. 7. 
VIT. Of the Senfe of Extenfion. 
The organ of touch is properly the fcr.fc of preTure, but the 
mufcular fibres themfelves conftitute the organ of fenfe, that 
feels extenfion. The fenfe of preflure is always attended with 
the ideas of the figure and folidity of the object, neither of 
which accompany our perception of extenfion. The whole fet 
of mufcles, whether they are hollow ones, as the heart, arteries, 
and inteftines, or longitudinal ones attached to bones, contract 
themfelves, whenever they are ftimulated by forcible elonga- 
tion ; and it is obfcrvable, that the white mufcles, which 
conftitute the arterial fyftem, feem to be excited into contrac- 
tion from no other kinds of ftimulus, according to the experi- 
ments of Haller. And hence the violent pain in fome inflam- 
mations, as in the paronychia, obtains immediate relief by cut- 
ting the membrane, that was ftretched by the tumour of the 
fubjacent parts. 
Hence the whole mufcular fyftem may be confidered as one 
organ of fenfe, and the various attitudes of the body, as ideas be- 
longing to this organ, of many of which we are hourly con- 
feious, while many others, like the irritative ideas of the other 
fenfes, are performed without our attention. 
When the mufcles of the heart ceafe to a<ft, the refluent 
blood again diftends or elongates them ; and thus irritated they 
contract as before. The fame happens to the arterial fyftem, 
and I fuppofe to the capillaries, inteftines, and various glands of 
the body. 
When the quantity of,urine, or of excrement, diftends the 
bladder, or rectum, thofe parts contrail, and exclude their con- 
tents, and many other mufcles by aflbeiation adt along with 
them ; but if thefe evacuations are not foon complied with, 
pain is produced by a little further extenfion of the mufcular fi- 
bres : a fimilar pain is caufed in the mufcles, when a limb is 
much extended for the reduction of diflocated bones ; and in 
the punifhment of the rack : and in the painful cramps of the 
calf of the leg, or of other mufcles, for a greater degree of con- 
traction of a mufcle, than the movement of the two bones, to 
which its ends are affixed, will admit of, mull give fimilar pain 
to that, which is produced by extending it beyond its due 
length. And the pain from pumftures or incifions arifes from 
the diftention of the fibres, as the knife pafles through them ; 
for it nearly ceafes as foon as the divifion is completed. 
All thefe motions of the mufcles, that are thus naturally ex- 
cited by the ftimu'us of diftending bodies, arc alfo liable to be 
called into ftrong adfion by their catenation with the irritations 
or Sect. XIV. 8. 
OF IDEAS. 
93 
or fenfalions produced by the momentum of the progreffive par- 
ticles of blood in the arteries, as in inflammatory fevers, or by 
acrid fubftances on other feniibie organs, as in the ftrangury, or 
tenefmus, or cholera. 
We (hall conclude this account of the fenfe of extenfion by 
obferving, that the want of its object is attended with a difagree- 
able fenfation, as well as the excefs of it. In thofe hollow inuf- 
cles, which have been accuftonred to it, this difagreeabie fenfa- 
tion is called faintnefs, emptinefs, and finking; and, when it 
arifes to a certain degree, is attended with fyncope, or a total 
quiefcence of all motions, but the internal irritative ones, as 
happens from fudden lofs of blood, or in the operation of tap- 
ping in the dropfy. 
VIII. Of the Appetites of Hunger Thirf^ Heat^ Extenfion) the want 
of Frejh Airy Animal LoW) and the Suckling of Children. 
Hunger is moft probably perceived by thofe numerous rami- 
fications of nerves that are feen about the upper opening of the 
itomach; and thirft by the nerves about the fauces, and the top 
of the gula. The ideas of thefe fenfes are few in the generality 
of mankind, but are more numerous in thofe, who by difeafe, or 
indulgence, defire particular kinds of foods or liquids. 
A fenfe of heat has already been fpoken of, which may with 
propriety be called an appetite, as we painfully defire it, when it 
is deficient in quantity. 
The fenfe of extenfion may be ranked amongft thefe appe- 
tites, fince the deficiency of its object gives diiagreeable fenfa- 
tion ; when this happens in the arterial fyftem, it is called faint- 
nefs, and feems to bear fome analogy to hunger and to cold ; 
which like it are attended with emptinefs of a part of the vafcu- 
lar fyftem. 
The fenfe of want of frefh air has not been attended to, but 
is as diftimfl as the others, and the firft perhaps that we experi- 
ence after our nativity; from the want of the object of this 
fenfe many difeafes are produced, as the jail-fever, plague, and 
other epidemic maladies. Animal love is another appetite, 
which occurs later in life, and the females of lactiferous animals 
have another natural inlet of pleafure or pain from the fuckling 
their offspring. The want of which, either owing to the death 
of their progeny, or to the faflhion of their country, has been fa- 
tal to many of the fex. The males have alfo pectoral glands, 
which are frequently turgid with a thin milk at their nativity, 
and are furnifhed with nipples, which erect on titillation like 
thofe of the female; but which feem new to be of no further 
ufe. 94 
PRODUCTION, &c. 
Sect. XIV. 9. 
ufe, owing perhaps to feme change which thefe animals have 
undergone in the gradual progreflion of the formation of the 
earth, and of all that it inhabit. 
Thefe feven laft mentioned fenfes may properly be termed 
appetites, as they differ from thofe of touch, fight, hearing, tafte, 
and fmell, in this refpccl; that they are affected with pain as 
well by the defeat of their objects as by the excefs of them, 
which is not fo in the latter. Thus cold and hunger give us 
pain, as well as an excefs of heat or fatiety; but it is not fo 
with darknefs and filence. 
IX. Before we conclude this Section on the organs of fenfe, 
we muft obferve, that, as far as we know, there are many more 
fenfes than have been here mentioned, as every gland feems to 
be influenced to feparate from the blood, or to abforb from the 
cavities of the body, or from the atmofphcre, its appropriated 
fluid, by the ftimulus of that fluid on the living gland ; and not 
by mechanical capillary abforption, nor by chemical affinity. 
Hence it appears, that each of thefe glands muft have a peculiar 
organ to perceive thefe irritations, but as thefe irritations are not 
fucceeded by fenfation, they have not acquired the names of 
fenfes. 
However when thefe glands are excited into motions ftronger 
than ufual, either by the acrimony of their fluids, or by their 
own irritability being much increafed, then the fenfation of pain 
is produced in them as in all the other fenfes of the body ; and 
thefe pains are all of different kinds, and hence the glands at 
this time really become each a different organ of fenfe, though, 
thefe different kinds of pain have acquired no names. 
Thus a great excefs of light does not give the idea of light but 
of pain ; as in forcibly opening the eye when it is much infla- 
med. The great excefs of preflure or diftention, as when the 
point of a pin is prefled upon our fkin, produces pain, (and when 
this pain of the fenfe of diftention is flighter, it is termed itch- 
ing, or tickling), without any idea of folidity or of figure : an 
excefs of heat produces fmarting, of cold another kind of pain ; 
it is probable by this fenfe of heat the pain produced by cauftic 
bodies is perceived, and of ele<ffricity, as all thefe are fluids, that 
permeate, diftend, or dccompofe the parts that feel them. 
SECT. Sect. XV. 1. 1. 
CLASSES OF IDEAS. 
95 
SECT. XV. 
OF THE CLASSES OF IDEAS. 
I. 1. Ideas received in tribes. 2. We combine them further, or ab- 
Jlracl from thefe tribes. 3. Complex ideas. 4. Compounded 
ideas. $. Simple ideas, modes, fubylances, relations, general ideas. 
6. Ideas of reflexion. 7. Memory and imagination imperfectly 
defined. Ideal prefence. Memorandum-rings. II. I. Irrita- 
tive ideas. Perception. 2. Senfitive ideas, imagination. 3. 
Voluntary ideas, recollection. 4. Aff dated ideas, fuggeflion. 
III. I. Definitions of perception, memory. 2. Reafoning, judg- 
ment, doubting, diflinguijhing, comparing. 3. Invention. 4. 
Confcioufnefs. 5. Indentity. 6. Lapfe of time. Freewill. 
I. i. As the conftituent elements of the material world are 
only perceptible to our organs of fenfe in a ftatc of combination ; 
it follows, that the ideas or fenfual motions excited by them, are 
never received fingly, but ever with a greater or lefs degree of 
combination. So the colours of bodies or their hardnefl'es oc- 
cur with their figures: every fmell and tafte has its degree of 
pungency as well as its peculiar flavour : and each note in mufic 
is combined with the tone of fome inftrument. It appears from 
hence, that we can be fenfible of a number of ideas at the fame 
time, fuch as the whitenefs, hardnefs, and coldnefs of a fnow- 
ball, and can experience at the fame time many irritative ideas 
of furrounding bodies, which we do not attend to, as mentioned 
in Section VIL 3. 2. But thofe ideas which belong to the fame 
fenfe, feem to be more eafily combined into fynchronous tribes, 
than thofe which were not received by the fame fenfe, as we 
can more eafily think of the whitenefs and figure of a lump of 
fugar at the fame time, than the whitenefs and fweetnefs of it. 
2. As thefe ideas, or fenfual motions, are thus excited with 
greater or lefs degrees of combination ; fo we have a power, 
when we repeat them either by our volition or fcnfation, to in- 
creafe or diminilh this degree of combination, that is, to form 
compounded ideas from thofe, which were more Ample ; and ab- 
ft raft ones from thofe, which were more complex, when they 
were firft excited ; that is, we can repeat a part or the whole of 
thofe fenfual motions, which did conftitute our ideas of percep- 
tion ; and the repetition of which now conftitutes our ideas of 
recollection, or of imagination. 
3. Thofe ideas, which we repeat without change of the quan- 
tity of that combination, with which we firlt received them, are 
caiied 96 
CLASSES OF IDEAS. 
Sect. XV. 1.4. 
called complex ideas, as when you recoiled Weftminfter Ab- 
bey, or the planet Saturn : but it muft be obferved, that thefe 
complex ideas, thus re-excited by volition, fenfation, or affocia- 
tion, are feldom perfect copies of their correfpondent percep- 
tions, except in our dreams, where other external objefts do not 
detract our attention. 
4. Thofe ideas, which are more complex than the natural ob- 
jects that firft excited them, have been called compounded ideas, 
as when we think of a fphinx, or griffin. 
5. And thofe that are lefs complex than the correfpondent 
natural objects, have been termed abftradted ideas ; thus fweet- 
nefs, and whitenefs, and folidity, are received at the fame time 
from a lump of fugar, yet I can recollect any of thefe qualities 
without thinking of the others, that were excited along with 
them. See Sect. XVI. 17. 
When ideas are fo far abftraCted as in the above example, 
they have been termed fimple by the writers of metaphyfics, and 
feem indeed to he more complete repetitions of the ideas or fen- 
fual motions, originally excited by external objects. 
Other claffes of thefe ideas, where the abftraCtion has not been 
fo great, have been termed, by Mr. Locke, modes, fubftances, 
ana relations, but they feem only to differ in their degree of ab- 
ftraction from the complex ideas that were at firft excited ; for 
as thefe complex or natural ideas are themfelves imperfect copies 
of their correfpondent perceptions, fo thefe abftract or general 
ideas are only ftill more imperfect copies of the fame percep- 
tions. Thus when I have feen an object but once, as a rhinoce- 
ros, my abftraft idea of this animal is the fame as my complex 
one. I may think more or lefs diftindtly of a rhinoceros, but it 
is the very rhinoceros that I faw, or fome part or property of 
him, which recurs to my mind. 
But when any clafs of complex objects becomes the fubject of 
converfation, of which I have feen many individuals, as a caftle 
or an army, fome property or circumftance belonging to it is 
peculiarly alluded to ; and then I feel in my own mind, that my 
abftract idea of this complex object is only an idea of that part, 
property, or attitude of it, that employs the prefent converfation, 
and varies with every fentence that is fpoken concerning it. So 
if any one fhould fay, " one may fit upon a horfe fafer than on 
a camel," my abftract idea of the two animals includes only an 
outline of the level back of the one, and the gibbofity on the 
back of the other. What noife is that in the ftreet ?-Some 
horfes trotting over the pavement. Here my idea of the horfes 
includes principally the Ihape and motion of their legs. So 
alfo the abftract ideas of goodnefs and courage are ftill more im- 
perfect Sect. XV. i. 6. 
CLASSES OF IDEAS. 
97 
jperfeCt reprefentations of the objects they were received from ; 
for here we abfiraft the material parts, and recollect only the 
qualities. 
Thus we abftrafl fo much from fome of our complex ideas, 
that at length it becomes difficult to determine of what percep- 
tion they partake; and in many inftances our idea feems to be 
no other than of the found or letters of the word, that Rands 
for the collective tribe, of which we are faid to have an abRra£ted 
idea, as noun, verb, chi man a, apparition. 
Mr. Horne Tooke alfo, in his Diverfions of Purley, has very 
ingenioully (hewn, that what were called general ideas, are in 
reality only general terms; or words which lignify any parts of 
a complex object. Whence arifes much error in our verbal 
reafoning, as the fame word has different lignifications. And 
hence thofe, who can think without words, reafon more accu= 
rately than thofe, who only compare the ideas fuggeRed by 
words ; a rare faculty, which diffinguiRies the writers of phi= 
lofophy from thofe of fophiRry. See Clafs III. 2. 2. 3. 
6. Ideas have been divided into thofe of perception and thofe 
of reflection, but as whatever is perceived muff be external to 
the organ that perceives it, all our ideas muR originally be ideas 
of perception. 
7. Others have divided our ideas into thofe of memory and 
thofe of imagination ; they have faid that a recollection of ideas 
in the order they were received conRitutes memory, and with- 
out that order imagination ; but all the ideas of imagination, ex- 
cepting the few that are termed fimple ideas, are parts of trains 
or tribes in the order they were received ; as if I think of a 
fphinx, or a griffin, the fair face, bofom, wings, claws, tail, are 
all complex ideas in the order they were received: and it be- 
hoves the writers, who adhere to this definition, to determine^ 
how fmall the trains muR be, that fliall be called imagination ; 
and how great thofe, that fliall be called memory. 
Others have thought that the ideas of memory have a greater 
vivacity than thofe of imagination: but the ideas of a perfon in 
fleep, or in a waking reverie, where the trains connected with 
fenfation are uninterrupted, are more vivid and diRinCt than 
thofe of memory, fo that they cannot be diRinguiffied by this 
criterion. 
The very ingenious author of the Elements of Criticifm has 
defcribed what he conceives to be a fpecies of memory, and calls 
it ideal prefence ; but the inRances he produces are the reveries 
of fenfation, and are therefore in truth connexions of the imag- 
ination, though they are recalled in the order they were received. 
The ideas connected by afl'oeiation are in common difeourfe 
Vol, I. O attributed 98 
CLASSES OF IDEAS. 
Sect. XV. 2. 1. 
attributed to memory, as we talk of memorandum-rings, and 
tie a knot on our handkerchiefs to bring fomething into our 
minds at a diftance of time. And a fchool-boy who can repeat, 
a thoufand unmeaning lines in Lilly's Grammar, is faid to have 
a good memory. But thefe have been already (hewn to belong 
to the clafs of affociation ; and are termed ideas of fuggeftion. 
IL Laftly, the method already explained of clafling ideas into 
thofe excited by irritation, fcnfation, volition, or affociation, we 
hope will be found more convenient both for explaining the 
operations of the mind, and for comparing them with thofe of 
the body ; and for the illuftration and the cure of the difeafes of 
both, and which we (hall here recapitulate. 
i. Irritative ideas are thofe, which are preceded by irritation, 
which is excited by objects external to the organs of fenfe : as 
the idea of that tree, which either I attend to, or which I fhun 
in walking near it without attention. In the former cafe it is 
termed perception, in the latter it is termed fimply an irritative 
idea. 
2. Senfitive ideas are thofe, which are preceded by the fen- 
fation of pleafure or pain ; as the ideas, which conftitutc our 
dreams or reveries, this is called imagination. 
3. Voluntary ideas are thofe, which are preceded by voluntary 
exertion, as when I repeat the alphabet backwards : this is call- 
ed recollection. 
4. AlTociate ideas are thofe, which are preceded by other 
ideas or mufcular motions, as when we think over or repeat the 
alphabet by rote in its ufual order ; or fing a tune we are accuf- 
tomed to ; this is called fuggeftion. 
III. 1. Perceptions fignify thofe ideas, which are preceded by 
irritation and fucceeded by the fenfation of pleafure or pain, 
for whatever excites our attention interefts us ; that is, it is ac- 
companied with pleafure or pain ; however flight may be the 
degree or quantity of either of them. 
The word memory includes two claffes of ideas, either thofe 
which are preceded by voluntary exertion, or thofe which are 
fuggefted by their aflbeiations with other ideas. 
2. Reafoning is that operation of the fenforium, by which we 
excite two or many tribes of ideas; and then re-excite the ideas, 
in which they differ, or correfpond. If we determine this differ- 
ence, it is called judgment; if wre in vain endeavour to deter- 
mine it, it is called doubting. 
If we re-excited the ideas, in which they differ, it is called 
diftinguilhing. If we re-excite thofe in which they correfpond, 
it is called comparing. 
3. Invention is an operation of the fenforium, by which we 
voluntarily Sect. XV. 3.4. 
CLASSES OF IDEAS. 
99 
voluntarily continue to excite one train of ideas, fuppofe the de- 
fign of railing water by a machine ; and at the lame time attend 
to all other ideas, which are connected with this by every kind 
of catenation ; and combine or feparate them voluntarily for the 
purpofe of obtaining fome end. 
For we can create nothing new, wc can only combine or fepa- 
rate the ideas, which we have already received by our percep- 
tions : thus if I wifh to reprefent a monfter, I call to my mind 
the ideas of every thing difagreeable and horrible, and combine 
the naftinefs and gluttony of a hog, the ftupidity and obftinacy 
of an afs, with the fur and awkwardnefs of a bear, and call the 
new combination Caliban. Yet fuch a monfter may exift in 
nature, as all his attributes are parts of nature. So when I wifh 
to reprefent every thing, that is excellent and amiable ; when I 
combine benevolence with cheerfulnefs, wifdom, knowledge, 
tafte, wit, beauty of perfon, and elegance of manners, and aflb- 
ciate them in one lady as a pattern to the world, it is called in- 
vention ; yet fuch a perfon-may exift,-fuch a perfon does ex- 
ift !-It is , who is as much a monfter as Caliban. 
4. In refpe€t to confcioufnefs, we are only confcious of our 
exiftence, when we think about it; as we only perceive the 
lapfe of time, when we attend to it; when we are bufied about 
other objects, neither the lapfe of time nor the confcioufnefs of 
our own exiftence can occupy our attention. Hence, when we 
think of our own exiftence, we only excite abftrafted or reflex 
ideas (as they are termed), of our principal pleafures or pains, of 
our defires or averfions, or of the figure, folidity, colour, or 
other properties of our bodies, and call that a<ft of the fenfori- 
um a confcioufnefs of ©ur exiftence. Some philofophers, I be- 
lieve it is Des Cartes, has faid, " I think, therefore I exift." 
But this is not right rcafoning, becaufe thinking is a mode of 
exiftence; and it is thence only faying, " I exift, therefore I 
exift." For there are three modes of exiftence, or in the lan- 
guage of grammarians three kinds of verbs. Firft, limply 1 am, 
or exift. Secondly, I am acting, or exift in a ftate of activity, 
as I move. Thirdly, I am fuffering, or exift in a ftate of being 
afled upon, as I am moved. The when, and the where, as ap- 
plicable to this exiftence, depends on the fucceflive motions of 
our own or of other bodies ; and on their refpective fituations, 
as fpoken of, Secft. XIV. 2. 5. 
5. Our identity is known by our acquired habits or catenated 
trains of ideas and mufcular motions; and perhaps, when wc 
compare infancy with old age, in thofe alone can our identity be 
fuppofed to exift. For what elfe is there of fimilitude between 
tl^e firft fpeck of living entity and the mature man ?-every de- 
duflion 100 
CLASSES OF IDEAS. 
$ECT. XV. 3. 6. 
dudion of reafoning, every fentiment or pafllon, with every fibre 
of the corporeal part of our fyftem, has been fubjed: almoft to 
annual mutation ; while fome catenations alone of our ideas and 
mufcular anions have continued in part unchanged. 
By the facility, with which we can in our waking hours vol- 
untarily produce certain fucceffive trains of ideas, we know by 
experience, that we have before reproduced them ; that is, we 
are confcious of a time of our exiftence previous to the prefent 
time ; that is, of our identity now and heretofore. It is thefe 
habits of action, thefe catenations of ideas and mufcular mo- 
tions, which begin with life, and only terminate with it; and 
which we can in fome meafure deliver to our pofterity; as ex- 
plained in Sed. XXXIX. 
6,. When the progrelfive motions of external bodies make a 
part of our prefent catenation of ideas, we attend to the lapfe of 
time; which appears the longer, the more frequently we thus 
attend to it •, as when we exped: fomething at a certain hour, 
which much interefts us, whether it be an agreeable or difagree^ 
able event $ or when we count the palling feconds on a flop- 
watch. 
When an idea of our own perfon, or a reflex idea of our 
pleafures and pains, defires and averlions, makes a part of this 
Catenation, it is termed confcioufnefs; and if this idea of con- 
feioufnefs makes a part of a catenation, which we excite by rec- 
ollection, and know by the facility with which we excite it, that 
we have before experienced it, it is called identity, as explained 
above. 
7. In refped; to freewill, it is certain, that we cannot will to 
|hink of a new train of ideas, without previoufly thinking of the 
firft link of it; as I cannot will to think of a black fwan, with- 
out previoufly thinking of a black fwan. But if I now think of 
a tail, I can voluntarily recoiled: all animals, which have tails ; 
my will is fo far free, that I can purfue the ideas linked to this 
idea of tail, as far as my knowledge of the fubjed extends ; but 
to will without motive is to will without defire or averfion ; 
which is as abfurd as to feel without pleafure or pain ; they are 
both fclecifms in the terms. So far are we governed by the 
catenations of motions, which afied both the body and the mind 
pf man, and which begin with our irritability, and end with it. 
SECT. Sect. XVL i. 
OF INSTINCT. 
101 
SECT. XVL 
OF INSTINCT. 
HAUD EQUIBEM CREDO, QUIA SIT DIVINITUS ILLIS 
INGENIUM, AUT RERUM FATO PRUDENTIA MAJOR. 
VIRG. GEORG. L. I. 415. 
I. InfiinElive actions defined. Of connate pajfions. II. Of the fen- 
fations and motions of the foetus in the womb. III. Some animals 
are more perfectly formed than others before nativity. Of learn- 
ing to walk. IV. Of the fwallowing, breathing,fucking,peckings 
and lapping of young animals. V. Of the fenfe offmell, and its 
ufes to animals. Why cats do not eat their kittens. VI. Of the 
accuracy of fight in mankind, and theirfenfe of beauty. Of the 
fenfe of touch in elephants, monkies, beavers, men. VII. Of nat- 
ural language. VIII. The origin of natural language ; i. the 
language of fear ; 2. of grief; 3. of tender pleasure ; 4. offe- 
rene pleafure ; g. of anger ; 6. of attention. IX. Artificial lan- 
guage of turkies, hens, ducklings, wagtails, cuckoos, rabbits, dogs, 
and nightingales. X. Of mufic ; of tooth-edge ; of a good ear ; 
of architecture. XL Of acquired knowledge; of foxes, rooks, 
fieldfares, lapwings, dogs, cats, horfes, crows, pelicans, the tiger, 
and rattlefnake. XII. Of birds of paffage, dormice, fflakes, bats, 
fwallows, quails, ring-doves, the flare, chaffinch, hoopoe, chatterer, 
hawfinch, crofs-bill, rails and cranes. XIII. Of birds' nefis ; of 
the cuckoo ; of fwallows' nefis ; of the taylor bird. XIV. Of the 
old foldier ; of haddocks, cods, and dog-fifh ; of the remora ; of 
crabs, herrings, andfalmon. XV. Offpiders, caterpillars, ants, 
and the ichneumon. XVI. 1. Of locufls, gnats; 2. bees ; 3. 
dormice, flies, worms, ants, and wafps. XVII. Of the faculty 
that diflinguifhes man from the brutes. 
I. All thofe internal motions of animal bodies, which con- 
tribute to digeft their aliment, produce their fecretions, repair 
their injuries, or increafe their growth, are performed without 
our attention or confcioufnefs. They exift as well in our fleep, 
as in our waking hours, as well in the foetus during the time 
of geftation, as in the infant after nativity, and proceed with 
equal regularity in the vegetable as in the animal fyftem. Thefe 
motions have been fhewn in a former part of this work to de- 
pend on the irritations of peculiar fluids, and as they have never 
been clafled amongft the inftinftive addons of animals, are pre- 
cluded from our prefent difquifition. 
But 102 
OF INSTINCT. 
Sect. XVI. 2. 
But all thofe aftions of men or animals, that are attended 
with confcioufnefs, and feem neither to have been directed by 
their appetites, taught by their experience, nor deduced from ob- 
fervation or tradition, have been referred to the power of in- 
ftinft. And this power has been explained to be a divine fome- 
thingy a kind of infpiration ; whilft the poor animal, that poflelT- 
es it, has been thought little better than a machine ! 
The irkfomenefs, that attends a continued attitude of the body, 
or the pains, that we receive from heat, cold, hunger, or other 
injurious circumftances, excite us to general locomotion : and our 
fenfes are fo formed and conftituted by the hand of nature, that 
certain objects prefent us with pleafure, others with pain, and 
we are induced to approach and embrace thefe, to avoid and 
abhor thofe, as fuch fenfations direct us. 
Thus the palates of fome animals are gratefully affected by 
the maftication of fruits, others of grains, and others of flelh ; 
and they are thence inftigated to attain, and confume thofe ma- 
terials ; and are furnilhed with powers of mufcular motion, and 
of digeftion proper for fuch purpofes. 
Thefe fenfations and defires conflitute a part of our fyftem, as 
our mufcles and bones conflitute another part : and hence they 
may alike be termed natural or connate; but neither of them can 
properly be termed injlinHive : as the word inftindl in its ufual 
acceptation refers only to the ahiions of animals, as above ex- 
plained : the origin of thefe ahiions is the fubjedl of our prefent 
inquiry. 
The reader is entreated carefully to attend to this definition 
of inf in clive actions, left by ufing the word inftimft without ad- 
joining any accurate idea to it, he may not only include the nat- 
ural defires of love and hunger, and the natural fenfations of 
pain or pleafure, but the figure and contexture of the body, and 
the faculty of reafon itfelf, under this general term. 
II. We experience fome fenfations, and perform fome ac- 
tions before our nativity ; the fenfations of cold and warmth, 
agitation and reft, fulnefs and inanition, are inftances of the 
former ; and the repeated ftruggles of the limbs of the foetus, 
which begin about the middle of geftation, and thofe motions 
by which it frequently wraps the umbilical chord around its 
neck or body, and even fometimes ties it in a knot ; are inftan- 
ces of the latter. (Smcllie's Midwifery, Vol. I. p. 182.) 
By a due attention to thefe circumftances many of the ac- 
tions of young animals, which at firft fight feemed only referable 
to an inexplicable inftinft, will appear to have been acquired like 
all other animal actions, that are attended with confcioufnefs, 
h Sect. XVI. 3. 
OF INSTINCT. 
103 
by the repeated efforts of our muffles under the conduct of our fenfi~ 
tions or deftres. 
The chick in the fhell begins to move its feet and legs on 
the fixth day of incubation (Mattreican, p. 138); or on the 
feventh day, (Langley); afterwards it is feen to move itfelf 
gently in the liquid that furrounds it, and to open and fhut its 
mouth, (Harvei, de Generat. p. 62, and 197. Form, de Poulet. 
ii. p. 129). Puppies before the membranes are broken, that 
involve them, are feen to move themfelves, to put out their 
tongues, and to open and fhut their mouths, (Harvey, Gipfoil, 
Riolan, Haller). And calves lick themfelves and fwallow many 
of their hairs before their nativity, which however puppies do 
not, (Swammerdam, p. 319. Flemyng Phil. Tranf. Ann. 1755, 
42). And towards the end of geftation, the foetufes of all ani- 
mals are proved to drink part of the liquid in which they fwim, 
(Haller. Phyfiol. T. 8. 204). The white of egg is found in 
the mouth and gizzard of the chick, and is nearly or quite 
confumed before it is hatched, (Harvei de Generat. 58). And. 
the liquor amnii is found in the mduth and ftomach of the human 
foetus, and of calves ; and how elfe fhould that excrement be 
produced in the inteftines of all animals, which is voided in 
great quantity foon after their birth ; (Gipfon Med. Effays, 
Edinb. V. i. 13. Halleri Phyfiolog. T. 3. p. 318. and T. 8.) 
In the ftomach of a calf the quantity of this liquid amounted to 
about three pints, and the hairs amongft it were of the fame col- 
our with thofe on its Ikin, (Blafii Anat. Animal, p. m. 122). 
Thefe fadds are attefted by many other writers of credit, befides 
thofe above mentioned. 
III. It has been deemed a furprifing inftance of inftinG, that 
calves and chickens fhould be able to walk by a few efforts al- 
moft immediately after their nativity: whilft the human infant 
in thofe countries where he is not encumbered with clothes, as 
in India, is five or fix months, and in our climate almoft a 
twelvemonth, before he can fafely ftand upon his feet. 
The ftruggles of all animals in the womb muft refemble their 
mode of fwimming, as by this kind of motion they can beft 
change their attitude in water. But the fwimming of the calf 
and chicken refembles their manner of walking, which they have 
thus in part acquired before their nativity, and hence accomplifli 
it afterwards with very few efforts, whilft the fwimming of the 
human creature refembles that of the frog, and totally differs 
from his mode of walking. 
There is another circumftance to be attended to in this affair, 
that not only the growth of thofe peculiar parts of animals, 
which are firft wanted to fecure their fubfiftence, are ih general 
furtheft 104 
OF INSTINCT. 
Sect. XVI. 4. 
furtheft advanced before their nativity : but fome animals com6 
into the world more completely formed throughout their whole 
fyftem than others ; and are thence much forwarder in all their 
habits of motion. Thus the colt, and the lamb, are much more 
perfect animals than the blind puppy, and the naked rabbit; and 
the chick of the pheafant, and the partridge, has more perfect 
plumage, and more perfect eyes, as well as greater aptitude to 
locomotion, than the callow neftlings of the dove, and of the 
wren. The parents of the former only find it neceffary to fliew 
them their food, and teach them to take it up; whilft thofe of 
the latter are obliged for many days to obtrude,it into their 
gaping mouths. 
IV. From the fads mentioned in No. 2. of this Section, it is 
evinced that the foetus learns to fwallow before its nativity ; 
for it is feen to open its mouth, and its ftomach is found filled 
with the liquid that furrounds it. It opens its mouth, either 
inftigated by hunger, or by the irkfomenefs of a continued at- 
titude of the mufcles of its face ; the liquor amnii, in which it 
fwims, is agreeable to its palate, as it confifts of a nourifhing 
material, (Haller. Phyf. T. 8. p. 204). It is tempted to expe- 
rience its tafte further in the mouth, and by a few efforts learns 
to fwallow, in the fame manner as we learn all other animal ac- 
tions, which are attended with confcioufnefs, by the repeated ef- 
forts of our mufcles under the conduct of our fenfations or volitions. 
The infpiration of air into the lungs is fo totally different 
from that of fwallowing a fluid in which we are immerfed, that 
it cannot be acquired before our nativity. But at this time, 
when the circulation of the blood is no longer continued through 
the placenta, that fuftbeating fenfition, which we feel about the 
precordia, when wre are in want of frefli air, difagreeably af- 
fects the infant: and all the mufcles of the body are excited 
into aftion to relieve this oppreffion ; thofe of the breaft, ribs, 
and diaphragm are found to anfwer this purpofe, and thus ref- 
piratiou is difeovered, and is continued throughout our lives, as 
often as the oppreflion begins to recur. Many infants, both of 
the human creature, and of quadrupeds, ftruggle for a minute 
after they are born before they begin to breathe, (Haller. Phyf. 
T. 8. p. 400. ib. pt. 2. p. 1). Mr. Buffon thinks the action of the 
dry air upon the nerves of fmell of new-born animals, by pro- 
ducing an endeavour to fneeze, may contribute to induce this 
firft infpiration, and that the rarefaction of the air by the 
warmth of the lungs contributes to induce expiration, (Hift. 
Nat. Tom. 4. p. 174). Which latter it may efleCt by produ- 
cing a difagrceable fenfation by its delay, and a confequent ef- 
fort Sect. XVI. 5. r. 
OF INSTINCT. 
105 
fort to relieve it. Many children fneeze before they refpire, but 
not all, as far as I have obferved, or can learn from others. 
At length, by the direction of its fenfe of fmell, or by the offi- 
cious care of its mother, the young animal approaches the odo- 
riferous rill of its future nourilhment, already experienced tp 
fwallow. But in the a£l of fwallowing, it is neceflary nearly 
to clofe the mouth, whether the creature be immerfed in the fluid, 
it is about to drink, or not : hence, when the child firft attempts 
to fuck, it does not flightly comprefs the nipple between its lips, 
and fuck as an adult perfon would do, by abforbing the milk j 
but it takes the whole nipple into its mouth for this purpofe, 
comprefles it between its gums, and thus repeatedly chewing (as 
it were) the nipple, prefles out the milk ; exactly in the fame 
manner as it is drawn from the teats of cows by the hands of 
the milkmaid. The celebrated Harvey obferves, that the foetus 
in the womb muft have fucked in a part of its nourifhment, be* 
caufe it knows how to fuck the minute it is born, as any one 
may experience by putting a finger between its lips, and becaufe 
in a few days it forgets this art of fucking, and cannot without 
ibme difficulty again acquire it, (Exercit. de Gener. Anim. 48). 
The fame obfervation is made by Hippocrates. 
A little further experience teaches the young animal to fuck 
by abforption, as well as by compreffion ; that is, to open the 
chelt as in the beginning of refpiration, and thus to rarefy the 
air in the mouth, that the preflure of the deafer external atmof- 
phere may contribute to force out the milk. 
The chick yet in the (hell has learnt to drink by fwallowing 
a part of the white of the egg for its food ; but not having ex- 
perienced how to take up and fwallow folid feeds, or grains, is 
either taught by the felicitous induftry of its mother ; or by 
many repeated attempts is enabled at length to diftinguifh and 
to fwallow this kind of nutriment. 
And puppies, though they know how to fuck like other ani- 
mals from their previous experience in fwallowing, and in ref- 
piration ; yet are they long in acquiring the art of lapping with 
their tongues, which from the flaccidity of their cheeks, and 
length of their mouths, is afterwards a more convenient way 
for them to take in water. 
V. The fenfes of fmell and tafte in many other animals 
greatly excel thofe of mankind, for in civilized fociety, as cur 
victuals are generally prepared by others, and are adulterated 
with fait, fpice, oil, and empyreuma, we do not heftate about 
eating whatever is fet before us, and negleft to cultivate thefe 
fenfes : whereas other animals try every morfel by the fmell, be- 
fore they take it into their mouths, and by the tafte before they 
Vol. I. P fwallow 106 
OF INSTINCT. 
Sect. XVI. 6. 1, 
fwallow it; and are led not only each to his proper nourilhmenb 
by this organ of fenfe, but it alfo at a maturer age directs them 
in the gratification of their appetite of love. Which may be 
further underftood by confidering the fympathies of thefe parts 
defcribed in clafs IV. 2. 1.7. While the human animal is di- 
redted to the object of his love by his fenfe of beauty, as men- 
tioned in No. VI. of this Section. Thus Virgil Georg. III. 250. 
Nonne vides, ut tota tremor pertentat equorum 
Corpora, fi tantum notas odor attulit auras? 
Nonne canis nidum veneris nafutus odore 
Quxrit, et erranti trahitur fublambere lingua ? 
Refpuit at guftum cupidus, labiifque retractis 
Elevat os, trepidanfque novis impellitur seftris 
Inferit et vivum felici vomere femen.- 
Quam tenui filo csecos adneCtit amores 
Dodia Venus, vitaque monet renovate fa villain I 
Anow. 
The following curious experiment is related by Galen. ft On 
diffefting a goat great with young I found a brifk embryon, and 
having aetached it from the matrix, and fnatching it away be- 
fore it faw its dam, I brought it into a certain room, where 
there were many veffels, fome filled with wine, others with oil, 
fome with honey, others with milk, or fome other liquor ; and 
in others were grains and fruits ; we firft obferved the young 
animal get upon its feet, and walk ; then it fhook itfelf, and af- 
terwards fcratched its fide with one of its feet: then we faw it 
fmelling to every one of thefe things, that were fet in the room ; 
and when it had fmelt to them all, it drank up the milk." L. 
6. de locis. cap. 6. 
Parturient quadrupeds, as cats, and bitches, and fows, are 
led by their fenfe of fmell to eat the placenta as other common 
food ; why then do they not devour their whole progeny, as is 
reprefented in an ancient emblem of Time ? This is laid fome- 
times to happen in the unnatural ftate in which we confine 
fows j and indeed nature would feem to have endangered her 
offspring in this nice circumftance 1 But at this time the ftimu- 
lus of the milk in the tumid teats of the mother excites her to 
look out for, and to defire fome unknown circumftance to re- 
lieve her. At the fame time the fmell of the milk attracts the 
exertions of the young animals towards its fource, and thus the 
delighted mother difcovers a new appetite, as mentioned in 
Seif. XIV. 8. and her little progeny are led to receive and to 
communicate pleafure by this moft beautiful contrivance. 
VI. But though the human fpecies in fome of their fenfa- 
tions are much inferior to other animals, yet the accuracy of the 
fenfe Sect. XVI. 6. i. 
OF INSTINCT. 
107 
fenfe of touch, which they poffefs in fo eminent a degree, gives 
them a great fuperiority of underftanding ; as is well obferved 
by the ingenious Mr. Buffon. The extremities of other animals 
terminate in horns, and hoofs, and claws, very unfit for the fen- 
fation of touch ; whilft the human hand is finely adapted to en- 
compafs its object with this organ of fenfe. 
The elephant is indeed endued with a fine fenfe of feeling at 
the extremity of his probofcis, and hence has acquired much 
more accurate ideas of touch and of fight than molt other crea- 
tures. The two following inftances of the fagacity of thefe an- 
imals may entertain the reader, as they were told me by fome 
gentlemen of diftinct obfervation, and undoubted veracity, who 
had been much converfant with our eaftern fettlements. Firft, 
the elephants that are ufed to carry the baggage of our armies, 
are put each under the care of one of the natives of Indoftan, and 
whilft himfelf and his wife go into the woods to collecft leaves 
and branches of trees for his food, they fix him to the ground 
by a length of chain, and frequently leave a child yet unable to 
walk, under his protection : and the intelligent animal not only 
defends it, but as it creeps about, when it arrives near the ex- 
tremity of his chain, he wraps his trunk gently round its body, 
and brings it again into the centre of his circle. Secondly, the 
traitor elephants are taught to walk on a narrow path between 
two pit-falls, which are covered with turf, and then to go into 
the woods, and to feduce the wild elephants to come that way, 
who fall into thefe wells, whilft he paffes fafe between them : 
and it is univerfally obferved, that thofe wild elephants that ef- 
cape the fnare, purfue the traitor with the utmoft vehemence, 
and if they can overtake him, which fometimes happens, they 
always beat him to death. 
The monkey has a hand well enough adapted for the fenfe of 
touch, which contributes to his great facility of imitation ; but 
in taking objeds with his hands, as a ftick or an apple, he puts 
his thumb on the fame fide of them with his fingers, inftead of 
counteracting the preffure of his fingers with it: from this neg- 
leCT he is much flower in acquiring the figures of objeCts, as he 
is lefs able to determine the diftances or diameters of their parts, 
or to diftinguifh their vis inertiae from their hardnefs. Helve- 
tius adds, that the fhortnefs of his life, his being fugitive be - 
fore mankind, and his not inhabiting all climates, combine to 
prevent his improvement. (De 1'Efprit. T. i. p.) There is 
how'ever at this time an old monkey (hewn in Exeter Change, 
London, who having loft his teeth, when nuts are given him, 
takes a ftone into his hand, and cracks them with it one by one; 
thus ufing tools to effect his purpofe like mankind. 
The 108 
OF INSTINCT. 
Sect. XVI. 6. n 
The beftver is another animal that makes much ufe of his 
hands, and if we may credit the reports of travellers, is poffefl'ed 
of amazing ingenuity. This however, M. Buffon affirms, is on- 
ly where they exift in large numbers, and in countries thinly 
peopled with men ; while in France in their folitary ftate they 
ihew no uncommon ingenuity. 
Indeed all the quadrupeds, that have collar-bones, (claviculse) 
ufe their foreJimbs in fome meafure as we ufe our hands, as the 
cat, fquirrel, tyger, bear and lion ; and as they exercife the fenfe 
of touch more univerfally than other animals, fo are they more 
fagacious in watching and furprifing their prey. All thofe birds, 
that ufe their claws for hands, as the hawk, parrot, and cuckoo, 
appear to be more docile and intelligent; though the gregarious 
tribes of birds have more acquired knowledge. 
Now as the images, that are painted on the retina of the eye, 
are no other than figns, which recall to our imaginations the ob- 
jects we had before examined by the organ of touch, as is fully 
demonftrated by Dr. Berkeley in his treatife on vifion; it follows 
that the human creature has greatly more accurate and diftindt 
fenfe of vifion than that of any other animal. Whence as he 
advances to maturity he gradually acquires a fenfe of female 
beauty, which at this time diredts him to the objedl of his new 
paffion. 
Sentimental love, as diftinguifhed from the animal paffion of 
that name, with which it is frequently accompanied, con lifts in 
the defire or fenfation of beholding, embracing, and fainting a 
beautiful objedL 
The charadteriftic of beauty therefore is that it is the objedt 
of love : and though many other objedls are in common language 
called beautiful, yet they are only called fo metaphorically, and 
ought to be termed agreeable. A Grecian temple may give us 
the pleafurable idea of fublimity, a Gothic temple may give us 
the pleafurable idea of variety, and a modern houfe the pleafur- 
able idea of utility ; mufic and poetry may infpire our love by 
affociation of ideas ; but none of thefe, except metaphorically, 
can be termed beautiful; as we have no wifh to embrace or fa- 
lute them. 
Our perception of beauty confifts in our recognition by the 
fenfe of vifion of thofe objects, firft, which have before infpired 
our love by the pleafure, which they have afforded to many of 
our fenfes : as to our fenfe of warmth, of touch, of fmell, of 
tafte, hunger and thirft ; and, fecondly, which bear any analo- 
gy of form to fuch objedls. 
When the babe, foon after it is born into this cold world, is 
applied to its mother's bofom ; its fenfe of perceiving warmth 
is Sect. XVI. 7. 1. 
OF INSTINCT. 
109 
is firft agreeably affected; next its fenfe of fmell is delighted 
with the odour of her milk; then its tafte is gratified by the fla- 
vour of it; afterwards the appetites of hunger and of thirft afford 
pleafure by the pofleflion of their objects, and by the fubfequent 
digeftion of the aliment; and, laftly, the fenfe of touch is de- 
lighted by the foftnefs and fmoothnefs of the milky fountain, 
the fource of fuch variety of happinefs. 
All thefe various kinds of pleafure at length become aflbeiated 
with the form of the mother's breaft; which the infant embra- 
ces with its hands, prefles with its lips, and watches with it« 
eyes; and thus acquires more accurate ideas of the form of its 
mother's bofom, than of the odour and flavour or warmth, 
which it perceives by its other fenfes. And hence at our ma- 
turer years, when any obje<T of vifion is prefented to us, which 
by its waving or fpiral lines bears any fimilitude to the form of 
the female bofom, whether it be found in a landfcape with foft 
gradations of rifing and defeending furface, or in the forms of 
fome antique vafes, or in other works of the pencil or the chiflel, 
we feel a general glow of delight, which feems to influence all 
our fenfes ; and, if the object be not too large, we experience an 
attraction to embrace it with our arms, and to falute it with our 
lips, as we did in our early infancy the bofom of out mother. And 
thus we find, according to the ingenious idea of Hogarth, that 
the waving lines of beauty were originally taken from the tem- 
ple of Venus. 
This animal attraction is love; which is a fenfation, when 
the objeCt is prefent; and a defire, when it is abfent. Which 
conftitutes the pureft fource of human felicity, the cordial drop 
in the otherwife vapid cup of life, and which overpays mankind 
for the care and labour, which are attached to the pre-eminence 
of his fituation above other animals. 
It fhould have been obferved, that colour as well as form fome- 
times enters into our idea of a beautiful object, as a good com- 
plexion for inftance, becaufe a fine or fair colour is in general 
a fign of health, and conveys to us an idea of the warmth of the 
objedt; and a pale countenance on the contrary gives an idea 
of its being cold to the touch. 
It was before remarked, that young animals ufe their lips to 
diftinguilh the forms of things, as well as their fingers, and 
hence we learn the origin of our inclination to falute beautiful 
objefts with our lips. For a definition of Grace, fee Clafs III. 
i. 2. 4. 
VII. There are two ways by which we become acquainted 
with the pafllons of others : firlt, by having obferved the effects 
pf them, as of fear or anger, on our own bodies, we know at 
fight 110 
OF INSTINCT. 
Sect. XVI. 8. i. 
fight when others arc under the influence of thefe affections. 
So when two cocks are preparing to fight, each feels the feath- 
ers rife round his own neck, and knows from the fame fign the 
difpofition of his adverfary : and children long before they can 
fpeak, or underftand the language of their parents, may be 
frightened by an angry countenance, or foothed by fmiles and 
blandifhments. 
Secondly, when we put ourfelves into the attitude that any 
paflion naturally occafions, we foon in fome degree acquire that 
paflion ; hence when thofe that fcold indulge themfelves in loud 
oaths, and violent actions of the arms, they increafe their anger 
by the mode of exprefling themfelves; and on the contrary the 
counterfeited fmile of plea fur e in difagreeable company foon 
brings along with it a portion of the reality, as is well illuftrated 
by Mr. Burke, (Eflay on the Sublime and Beautiful.) 
This latter method of entering into the paflions of others is 
rendered of very extenfive ufe by the pleafure we take in imita- 
tion, which is every day prefented before our eyes, in the a&ions 
©f children, and indeed in all the cuftoms and fafliions of the 
world. From this our aptitude to imitation, arifes what is gen- 
erally underftood by the word fympathy fo well explained by Dr. 
Smith of Glafgow. Thus the appearance of a cheerful coun- 
tenance gives us pleafure, and of a melancholy one makes us 
forrowful. Yawning and fometimes vomiting are thus propa- 
gated by fympathy, and fome people of delicate fibres, at the 
prefence of a fpeffacle of mifery, have felt pain in the fame 
parts of their own bodies, that were difeafed or mangled in the 
Ocher. Amongft the writers of antiquity Ariftotle thought this 
aptitude to imitation an eflential property of the human fpecies, 
and calls man an imitative animal. Ta tupoiptvov 
Thefe then are the natural figns by which we underftand each 
Other, and on this flender balls is built all human language. For 
without fome natural figns, no artificial ones could have been 
invented or underftood, as is very ingenioufly obferved by Dr. 
Reid, (Inquiry into the Human Mind.) 
VIII. The origin of this univerfal language is a fubjeT of the 
higheft curiofity, the knowledge of which has always been 
thought utterly inacceffible. A part of which we Haall however 
here attempt. 
Light, found, and odours, are unknown to the foetus in the 
womb, which, except the few fenfations and motions already 
mentioned, fleeps away its time infenfible of the bufy world. 
But the moment it arrives into day, it begins to experience 
many vivid pains and pleafures; thefe are at the fame time at- 
tended with certain mufcular motions, and from this their 
early, Sect. XVI. 8. 1. 
OF INSTINCT. 
111 
early, and individual aflbeiation, they acquire habits of occur- 
ring together, that are afterwards indiifoluble. 
I. Of Fear. 
As foon as the young animal is born, the firft important fen- 
fations, that occur to him, are occafioned by the oppreffion about 
his precordia for want of refpiration, and by his fudden tranfi- 
tion from ninety-eight degrees of heat into fo cold a climate.- 
He trembles, that is, he exerts alternately all the mufcles of his 
body, to enfranchife himfelf from the oppreffion about his bofom, 
and begins to breathe with frequent and fhort refpirations; at 
the fame time the cold contra&s his red (kin, gradually turning 
it pale; the contents of the bladder and of the bowels are evac- 
uated : and from the experience of thefe firft difagreeable fenfa- 
tions the paffion of fear is excited, which is no other than the 
expectation of difagreeable fenfations. This early affociation of 
motions and fenfations perfifts throughout life; the paffion of 
fear produces a cold and palelkin, with tremblings, quick refpi- 
ration, and an evacuation of the bladder and bowels, and thus 
conftitutes the natural or univerfal language of this paffion. 
On obferving a Canary bird this morning, January 28, 1772, 
at the houfe of Mr. Harvey, near Tutbury, in Derbyffiire, I was 
told it always fainted away, when its cage was cleaned, and de- 
fired to fee the experiment. The cage being taken from the 
ceiling, and its bottom drawn out, the bird began to tremble, 
and turned quite white about the root of his bill: he then open- 
ed his mouth as if for breath, and refpired quick, ftooft 
ftraighter up on his perch, hung his wings, fpread his tail, elofed 
his eyes, and appeared quite ftiff and cataleptic for near half an 
hour, and at length with much trembling and deep refpirations 
came gradually to himfelf. 
2. Of Grief. 
That the internal membrane of the noftrils may be kept al- 
ways moift, for the better perception of odours, there are two 
canals, that conduct the tears after they have done their office 
in moiftening and cleaning the ball of the eye into a fack, which 
is called the lacrymal fack ; and from which there is a duct, 
that opens into the noftrils : the aperture of this duct is formed 
of exquifite fenfibility, and when it is ftimulated by odorous 
particles, or by the drynefs or coldnefs of the air, the lack con- 
tracts itfelf, and pours more of its contained moifture on the or- 
gan of fmell. By this contrivance the organ is rendered more 
fit 112 
OF INSTINCT. 
Sect. XVI. 3. 2. 
fit for perceiving fuch odours, and is preferved from being in- 
jured by thofe that are more ftrong or corrofive. Many other 
receptacles of peculiar fluids difgorgc their contents, when the 
ends of their duds are ftimulated ; as the gallbladder, when the 
contents of the duodenum ftimulate the extremity of the com- 
mon bile dudt: and the falivary glands, when the termination 
of their dudts in the mouth are excited by the ftimulus of the 
food we mafticate. Atque veficulae feminales fuum exprimunt 
fiuidurn glande penis fricata. 
The coldnefs and drynefs of the atmofphere, compared with 
the warmth and moifture, which the new-born infant had juft 
before experienced, difagreeably affedt the aperture of this lacry- 
mal fack: the tears, that are contained in this fack, are poured 
into the noftrils, and a further fupply is fecreted by the lacry- 
mal glands, and diffufed upon the eye-balls ; as is very vifible in 
the eyes and noftrils of children foon after their nativity. The 
fame happens to us at our maturer age, for in fevere frofty 
weather, fnivelling and tears are produced by the coldnefs and 
drynefs of the air. 
But the lacrymal glands, which feparate the tears from the 
blood, are fituated on the upper external part of the globes of 
each eye ; and, when a greater quantity of tears are wanted, we 
contract the forehead, and bring down the eye-brows, and ufe 
many other diftortions of the face, to comprefs thefe glands. 
Now as the fufFocating fenfation, that produces refpiration, is 
removed almoft as foon as perceived, and does not recur again: 
this difagreeable irritation of the lacrymal dudls, as it muft fre- 
quently recur, till the tender organ becomes ufed to variety of 
odours, is one of the firft pains that is repeatedly attended to : 
and hence throughout our infancy, and in many people through- 
out their lives, all difagreeable fenfations are attended with fniv- 
elling at the nofe, a profufion of tears, and fome peculiar diftor- 
tions of countenance : according to the laws of early aflbeiation 
before mentioned, which conftitutes the natural or univerfal 
language of grief. 
You may aflure yourfelf of the truth of this obfervation, if 
you will attend to what pafles, when you read a diftrefsful tale 
alone before the tears overflow your eyes, you will invariably 
feel a titillation at that extremity of the lacrymal dudt, which 
terminates in the noftril, then the compreflion of the eyes fuc- 
ceeds, and the profufion of tears. 
Linnseus aflerts, that the female bear Iheds tears in grief; the 
fame has been faid of the hind, and fome other animals. 
3- Of Sect. XVI. 8. 3. 
OF INSTINCT. 
113 
3. Of Tender Pleafure. 
The firft moft lively impreflion of pleafure, that the infant 
enjoys after its nativity, is excited by the odour of its mother's 
milk. The^brgan of fmell is irritated by this perfume, and the 
lacrymal fack empties itfelfinto the noftrils, as before explained, 
and an increafe of tears is poured into the eyes. Any one may 
obferve this, when very young infants are about to fuck ; for at 
thofe early periods of life, the fenfation affects the organ of 
fmell, much more powerfully, than after the repeated habit of 
fmelling has inured it to odours of common ftrength : and in 
our adult years, the ftronger finells, though they are at the fame 
time agreeable to us, as of volatile fpirits, continue to produce 
an increafed fecretion of tears. 
The pleating fenfation of fmell is followed by the early af- 
fection of the infant to the mother that fuckles it, and hence the 
tender feelings of gratitude and love, as well as of hopelefs grief, 
are ever after joined with the titillation of the extremity of the 
lacrymal duCts, and a profufion of tears. 
Nor is it lingular, that the lacrymal fack Ihould be influenced 
by plealing ideas, as the fight of agreeable food produces the 
fame effeCt on the falivary glands. Ac dum vidimus in fom- 
niis lafeivx puellae fimulacrum tenditur penis. 
Lambs Ihake or wriggle their tails, at the time when they firft 
fuck, to get free of the hard excrement, which had been long 
lodged in their bowels. Hence this becomes afterwards a mark 
off pleafure in them, and in dogs, and other tailed animals. But 
cats gently extend and contract their paws when they are pleaf- 
ed, and purr by drawing in their breath, both which refemble 
their manner of fucking, and thus become their language of 
pleafure, for thefe animals having collar-bones ufe their paws 
like hands when they fuck, which dogs and fheep do not. 
4- Of Seretie Pleaf tire. 
In the action of fucking, the lips of the infant are clofed 
around the nipple of his mother, till he has filled his ftomach, 
and the pleafure occafioned by the flimulus of this g^teful food 
fucceeds. Then the fphincler of the mouth, fatigued by the 
continued action of fucking, is relaxed ; and the antagonift muf- 
cles of the face gently acting, produce the fmile of pleafure : 
as cannot but be feen by all who are converfant with children. 
Hence this fmile during our lives is affociated with gentle 
pleafure ; it is vifible in kittens, and puppies, when they are 
played with, and tickled ; but more particularly marks the hu- 
Vol. I. man 114 
OF INSTINCT. 
Sect. XVI. 8. 5. 
man features. For in children this expreflion of pleafure is 
much encouraged, by their imitation of their parents, or friends ; 
who generally addrefs them with a finding countenance : and 
hence fome nations are more remarkable for the gaiety, and oth- 
ers for the gravity of their looks. 
5- Qf 
The actions that conftitute the mode of fighting, are the im- 
mediate language of anger in all animals ; and a preparation 
for thefe actions is the natural language of threatening. Hence 
the human creature clenches his fill, and fternly furveys his ad- 
verfary, as if meditating where to make the attack ; the ram, 
and the bull, draws himfelf fome fteps backwards, and levels his 
horns ; and the horfe, as he moll frequently fights by ftriking 
with his hinder feet, turns his heels to his foe, and bends back 
his ears, to liften out the place of his adverfary, that the threat- 
ened blow may not be ineffectual. 
6. Of Attention. 
The eye takes in at once but half our horizon, and that only 
in the day, and our fmell informs us of no very diftant objects, 
hence we confide principally in the organ of hearing to apprize 
us of danger ; when we hear any the fmalleft found, that we 
cannot immediately account for, our fears are alarmed, we fuf- 
pend our fteps, hold every mufcle (till, open our mouths a little, 
ere£t our ears, and liften to gain further information : and this 
by habit becomes the general language of attention to objects of 
fight, as well as of hearing; and even to the fucceflive trains of 
our ideas. 
The natural language of violent pain, which is exprefled by 
writhing the body, grinning, and fcreaming ; and that of tumul- 
tuous plcafure, exprefled in loud laughter ; belong to SecStion 
XXXIV. on Difeafes from Volition. 
IX. It muft have already appeared to the reader, that all other 
animals, as well as man, are poffefled of this natural language of 
the paflions, exprefled in figns or tones; and we (hall endeav- 
our to evince, that thofe animals, which have preferved them- 
felves from being enflaved by mankind, and are affbeiated in 
flocks, are alfo poflefled of fome artificial language, and of fome 
traditional knowledge. 
* • •«••• 
The mother turkey, when (lie eyes a kite hovering high in air, 
has either feen her own parents thrown into fear at his pref- 
ence, or has by obfervation been acquainted with his dangerous 
defigns Sect. XVI. 9. 1. 
OF INSTINCT. 
115 
defigns upon her young. She becomes agitated with fear, and 
ufes the natural language of that paflion, her young ones catch 
the fear by imitation, and in an inftant conceal themfelves in 
the grafs. 
At the fame time that (he (hews her fears by her gcfture and 
deportment, Ihe ufes a certain exclamation, Koe-ut, Koe-ut, and 
the young ones afterwards know, when they hear this note, 
though they do not fee their dam, that the prefence of their ad- 
verfary is denounced, and hide themfelves as before. 
The wild tribes of birds have very frequent opportunities of 
knowing their enemies, by obferving the deftrudlion they make 
among their progeny, of which every year but a fmall part 
efcapes to maturity : but to our domeftic birds thefe opportuni- 
ties fo rarely occur, that their knowledge of their diftant ene- 
mies muff frequently be delivered by tradition in the manner 
above explained, through many generations. 
This note of danger, as well as the other notes of the mother- 
turkey, when (he calls her flock to their food, or to fleep under 
her wings, appears to be an artificial language, both as exprefied 
by the mother, and as underftood by the progeny. For a hen 
teaches this language with equal eafe to the ducklings, (he has 
batched from fuppofitious eggs, and educates as her own off- 
fpring : and the wagtails, or hedge-fparrows, learn it from the 
young cuckoo their fofler nurfling, and fupply him with food 
long after he can fly about, whenever they hear his cuckooing, 
which Linnaeus tells us, is his call of hunger, (Syft. Nat.) And 
all our domeftic animals are readily taught to come to us for 
food, when we ufe one tone of voice, and to fly from our anger, 
when we ufe another. 
Rabbits, as they cannot eafily articulate founds, and are form- 
ed into focieties, that live under ground, have a very different 
method of giving alarm. When danger is threatened, they 
thump on the ground with one of their hinder feet, and produce 
it found, that can be heard a great way by animals near the fur- 
face of the earth, which would feem to be an artificial fign both 
from its Angularity and its aptnefs to the fituation of the animal. 
The rabbits on the ifland of Sor, near Senegal, have white 
fleih, and are well tailed, but do not burrow in the earth, fo 
that we may fufpecl their digging themfelves houfes in this cold 
climate is an acquired art, as well as their note of alarm, (Adan- 
fon's Voyage to Senegal). 
The barking cf dogs is another curious note of alarm, and 
would feem to be an acquired language, rather than a natural 
fign : for " in the ifland of Juan Fernandes, the dogs did not 
attempt to bark, till feme European dogs were put among them, 
and 116 
OF INSTINCT. 
Sect. XVI. 10. 1. 
and then they gradually begun to imitate them, but in a ftrange 
manner at firft, as if they were learning a thing that was not 
natural to them," (Voyage to South America by Don G. Juan, 
and Don Ant. de Ulloa. B. 2. c. 4). 
Linnaeus alfo obferves, that the dogs of South America do not 
bark at ftrangers, (Syft. Nat.) And the European dogs, that 
have been carried to Guinea, are faid in three or four genera- 
tions to ceafe to bark, and only howl, like the dogs that are na- 
tives of that coaft, (World Difplayed, Vol. XVII. p. 26). 
A circumftance not dillimilar to this, and equally curious, is 
mentioned by Kircherus. de Mufurgia, in his Chapter de Luf- 
ciniis. " That the young nightingales, that are hatched under 
other birds, never fing till they are inftru&edby the company of 
other nightingales." And Jonllon affirms, that the nightingales 
that vifit Scotland, have not the fame harmony as thofe of Italy, 
(Pennant's Zoology, oftavo, p. 255); which would lead us to 
iufpect that the finging of birds, like human mufic, is an arti- 
ficial language rather than a natural expreffion of paffion. 
X. Our mufic like our language, is perhaps entirely conftitu- 
ted of artificial tones, which by habit fuggeft certain agreeable 
paffions. For the fame combination of notes and tones do not 
excite devotion, love, or poetic melancholy in a native of Indof- 
tan and of Europe. And " the Highlander has the fame war- 
like ideas annexed to the found of a bagpipe (an inftrument 
which an Englifliman derides), as the Englifliman has to that of 
a trumpet or fife," (Dr. Brown's Union of Poetry and Mufic, 
p. 58.) So "the mufic of the Turks is very different from the 
Italian, and the people of Fez and Morocco have again a differ- 
ent kind, which to us appears very rough and horrid, but is 
highly pleafing to them," (L'Arte Armonica a Giorgio Antoni- 
otto). Hence we fee why the Italian opera does not delight an 
untutored Englifliman ; and why thofe, who are unaccuftomed 
to mufic, are more pleafed with a tune the fecond or third time 
they hear it, than the firft. For then the fame melodious train 
of founds excites the melancholy, they had learned from the 
fong; or the fame vivid combination of them recalls all the 
mirthful ideas of the dance and company. 
Even the founds, that were once difagreeable to us, may by 
habit be affociated with other ideas, fo as to become agreeable. 
Father Lafitau, in his account of the Iroquois, fays the mufic 
and dance of thofe Americans have fomcthing in them extremely 
barbarous, which at firft difgufts. We grow reconciled to them 
by degrees, and in the end partake of them with pleafure, the 
lavages themfelves are fond of them to diftraciion," (Moeurs 
des Savages, Tom. ii.) 
There Sect. XVI. 10. 1. 
OF INSTINCT. 
117 
There are indeed a few founds, that we very generally aflb- 
ciate with agreeable ideas, as the whiffling of birds, or purring 
of animals, that are delighted ; and fome others, that we as gen- 
erally aflbciate with difagreeable ideas, as the cries of animals in 
pain, the hifs of fome of them in anger, and the midnight howl 
of beafts of prey. Yet we receive no terrible or fubiime ideas 
from the lowing of a cow, or the braying of an afs. Which 
evinces, that thefe emotions are owing to previous affociations. 
So if the rumbling of a carriage in the ftreet be for a moment 
miftaken for thunder, we receive a fubiime fenfation, which 
ceafes as foon as we know it is the noife of a coach and fix. 
There are other difagreeable founds, that are faid to fet the 
teeth on edge ; which, as they have always been thought a ne- 
ceflary effect of certain difeordant notes, become a prroper fub- 
ject of our inquiry. Every one in his childhood has repeatedly- 
hit a part of the glafs or earthen veflcl, in which his food has 
been given him, and has thence had a very difagreeable fenfa- 
tion in the teeth, which fenfation was defigned by nature to 
prevent us from exerting them on objects harder than themfelves. 
The jarring found produced between the cup and the teeth is 
always attendant on this difagreeable fenfation : and ever after 
when fuch a found is accidentally produced by the conflict of 
two hard bodies, we feel by afibciation of ideas the concomitant 
difagreeable fenfation in our teeth. 
Others have in their infancy frequently held the corner of a 
filk handkerchief in their mouth, or the end of the velvet cape 
of their coat, whilft their companions in play have plucked it 
.from them, and have given another difagreeable fenfation to 
their teeth, which has afterwards recurred on touching thofe 
materials. And the fight of a knife drawn along a china plate, 
though no found is excited by it, and even the imagination of 
fuch a knife and plate fo fcraped together, I know by repeated 
experience will produce the fame difagreeable fenfation of the 
teeth. 
Thefe circumftances indifputably prove, that this fenfation of 
the tooth-edge is owing to aflociated ideas ; as it is equally ex- 
citable by fight, touch, hearing, or imagination. 
In refpect to the artificial proportions of found excited by mu- 
fical inftruments, thofe, who have early in life aflociated them 
with agreeable ideas, and have nicely attended to diftinguiih 
them from each other, are faid to have a good ear, in that coun- 
try where fuch proportions are in falhion : and not from any 
fuperior perfection in the organ of hearing, or any inftindiive 
fympathy between certain founds and paflions. 
I have obferved a child to be exquifitely delighted with mufic, 
and 118 
OF INSTINCT. 
Sect. XVI. 11. 1.' 
and who could with great facility learn to fing any tune that he 
heard diftinctly, and yet whofe organ of hearing was fo imper- 
fect, that it was neceflary to fpeak louder to him in common 
converfation than to others. 
Our mufic, like our architecture, feems to have no founda- 
tion in nature, they are both arts purely of human creation, as 
they imitate nothing. And the profeflbrs of them have only 
clafled thofe circumltances, that are moft agreeable to the acci- 
dental talte of their age, or country ; and have called it Propor- 
tion. But this proportion mull always fluctuate, as it refts on 
the caprices, that are introduced into our minds by our various 
modes of education. And thefe fluctuations of tafte mull be- 
come more frequent in the prefent age, where mankind have 
cnfranchifed themfelves from the blind obedience to the rules of 
antiquity in perhaps every fcience, but that of architecture. See 
SeCt. XII. 7. 3. 
XI. There are many articles of knowledge, which the ani- 
mals in cultivated countries feem to learn very early in their 
lives, either from each other, or from experience, or obferva- 
tion : one of the molt general of thefe is to avoid mankind. 
There isfo great a refemblance in the natural language of the 
paflions of all animals, that we generally know, when they are 
in a pacific, or in a malevolent humour, they have the fame 
knowledge of us; and hence we can fcold them from us by 
fome tones and geftures, and could poflibly attract them to us 
by others, if they were not already apprized of our general ma- 
levolence towards them. Mr. Gmelin, ProfeiTor at Petcrfburg, 
allures us, that in his journey into Siberia, undertaken by order 
of the Emprefs of Rulfia, he faw foxes that exprefled no fear of 
himfelf or companions, but permitted him to come quite near 
them, having never feen the human creature before. And Mr. 
Bougainville relates, that at his arrival at the Malouine, or Falk- 
land's Iflands, which were not inhabited by men, all the ani- 
mals came about himfelf and his people ; the fowls fettling up- 
on their heads and flioulders, and the quadrupeds running about 
their feet. From the difficulty of acquiring the confidence of 
old animals, and the eafe of taming young ones, it appears 
that the fear, they all conceive at the fight of mankind, is an ac- 
quired article of knowledge. 
This knowledge is more nicely underftood by rooks, who are 
formed into focieties, an i build, as it were, cities over our heads ; 
they evidently diftinguifh, that the danger is greater when a 
man is armed with a gun. Every one has feen this, who in 
the fpring of the year has walked under a rookery with a gun in 
his hand : the inhabitants of the trees rife on their wings, and 
fcream Sect. XVI. n. r. 
OF INSTINCT. 
119 
fcream to the unfledged young to fhrink into their nefts from 
the fight of the enemy. T^e vulgar obferving this circum- 
ftance fo uniformly to occur, affert that rooks can fmell gun- 
powder. 
The fieldfares, (turdus pilaris) which breed in Norway, and 
come hither in the cold feafon for our winter berries ; as they 
arc aflbciated in flocks, and are in a foreign country, have evi- 
dent marks of keeping a kind of watch, to remark and announce 
the appearance of danger. On approaching a tree, that is cov- 
ered with them, they continue fearlefs till one at the extremity 
cf the bufh rifing on his wings gives a loud and peculiar note of 
alarm, when they all immediately fly, except one other, who 
continues till you approach fliil nearer, to certify as it were ths 
reality of the danger, and then he alfo flies off repeating the note 
of alarm. 
And in the woods about Senegal there is a bird called uett- 
uett by the negroes, and fquallers by the French, which, as foon 
as they fee a man, fet up a loud fcream, and keep flying round 
him, as if their intent was to warn other birds, which upon 
hearing the cry immediately take wing. Thefe birds are the 
bane of fportfmen, and frequently put me into a paflion, and 
obliged me to ihoot them, (Adanfon's Voyage to Senegal, 78). 
For the fame intent the leffer birds cf our climate teem to fly 
after a hawk, cuckoo, or owl, and fcream to prevent their com- 
panions from being furprifed by the general enemies of them- 
felves, or of their eggs and progeny. 
But the lapwing, (charadrius pluvialis Lin.) when her un- 
fledged offspring run about the marfhes, where they were hatch- 
ed, not only gives the note of alarm at the approach of men or 
dogs, that her young may conceal themfelves ; but flying and 
fcreaming near the adverfary, ihe appears more felicitous and 
impatient, as he recedes from her family, and thus endeavours 
to miflead him, and frequently fucceeds in her defign. Thefe 
laft inftances are fo appofite to the fituation, rather than to the 
natures of the creatures, that ufe them ; and are fo fimilar to 
the actions of men in the fame circumftances, that we cannot 
but believe, that they proceed from a fimilar principle. 
Mifs M. E. Jackfon acquainted me, that ihe witneffed this 
autumn an agreeable infiance of fagacity in a little bird, which 
feemed to ufe the means to obtain an end ; the bir,d repeatedly 
hopped upon a poppy-ftem, and ihook the head with its bill, till 
many feeds were fcattered, then it fettled on the ground, and 
eat the feeds, and again repeated the fame management. Sept, 
1, 1794. 
Ou the northern coait cf Ireland a friend of mine faw above 
a 120 
OF INSTINCT. 
Sect. XVI. u. i. 
a hundred crows at once preying upon mufcles ; each crow 
took a mufcle up into the air twenty or forty yards high, and 
let it fall on the Rones, and thus by breaking the (hell, got pof- 
(eflion of the animal.-A certain philofopher (I think it was 
Anaxagoras) walking along the fea-ihore to gather (hells, one of 
thefe unlucky birds miftaking his bald head for a (lone, drop- 
ped a (hell fifli upon it, and killed at once a philofopher and an 
oyfter. 
The Martin, hirundo urbica, is faid by Linnseus to dwell on 
the outfide of houfes in Europe under the eaves, and to return 
with the early foliage. And that, when it has built, the fpar- 
row, fringilla domeftica, frequently occupies the finifhed neft ; 
but that the martin convoking its companions, while fome guard 
the captive enemy, others bring clay, exactly clofe up the en- 
trance, and fly away leaving the intruder to be fuffocated. Syft. 
Natur. PaiT. Hirundo. A fimilar relation was printed many 
years ago in the Gentleman's Magazine. 
Our domeftic animals, that have fome liberty, are alfo poflefl- 
ed of fome peculiar traditional knowledge : dogs and cats have 
been forced into each other's fociety, though naturally animals 
of a very different kind, and have hence learned from each other 
to catalog's grafs (agroftis canina) when they are fick, to promote 
vomiting. I have feen a cat miftake the blade of barley for 
this grafs, which evinces it is an acquired knowledge. They 
have alfo learnt of each other to cover their excrement and urine; 
-about a fpoonful of water was fpilt upon my hearth from the 
tea-kettle, and I obferved a kitten cover it with allies. Hence 
this muft alfo be an acquired art as the creature miftook the ap- 
plication of it. 
To preferve their fur clean, and efpecially their whifkers, cats 
wafh their faces, and generally quite behind their ears, every time 
they eat. As they cannot lick thofe places with their tongues, 
they firft wet the infide of the leg with faliva, and then repeat- 
edly wafh their faces with it, which muft originally be an effect 
of reafoning, becaufe a means is ufed to produce an effect ; and 
feems afterwards to be taught or acquired by imitation, like the 
greateft part of human arts. 
Thefe animals feem to poflefs fomething like an additional 
fenfe by means of their whifkers; which have perhaps fome 
analogy to the antennae of moths and butterflies. The whifkers 
of cats confift not only of the long hairs on their upper lips, but 
they have alfo four or five long hairs (landing up from each eye- 
brow, and alfo two or three on each cheek ; all which when 
the animal erefts them, make with their points fo many parts 
©f the periphery of a circle, of an extent at lead equal to the 
circumference Sect. XVI. n. I. 
OF INSTINCT. 
121 
circumference of any part of their own bodies. With this in- 
ftrument, I conceive, by a little experience, they can at once de- 
termine, whether any aperture amongft hedges or fhrubs, in 
which animals of this genus live in their wild ftate, is large 
enough to admit their bodies ; which to them is a matter of 
the greateft confequence, whether purfuing or purfued. They 
have likewife a power of erecting and bringing forward the whif- 
kers on their lips; which probably is for the purpofe of feeling, 
whether a dark hole be further permeable. 
The antennae, or horns of butterflies and moths, who have 
awkward wings, the minute feathers of which are very liable to 
injury, ferve, I fuppofe, a fimilar purpofe of meafuring, as they 
fly or creep amongft the leaves of plants and trees, whither their 
wings can pafs without touching them. 
I this morning faw a terrier bitch repeatedly lick her paws, 
and wafh her face on both fides, and over her eyes, exactly as cats 
do ; from whom I fuppofe (he had acquired this art, as fhe liv- 
ed in the parlour with two of them. 
Mr. Leonard, a very intelligent friend of mine, faw a cat 
catch a trout by darting upon it in a deep clear water at the 
mill at Weaford, near Litchfield. The cat belonged to Mr. 
Stanley, who had often feen her catch fifh in the fame manner 
in fummer, when the mill-pool was drawn fo low that the fifh 
could be feen. I have heard of other cats taking fifh in fhallow 
water, as they ftood on the bank. This feems a natural art of 
taking their prey in cats, which their acquired delicacy by do- 
mcftication has in general prevented them from ufing, though 
their defire of eating fifh continues in its original ftrength. 
Mr. White, in his ingenious Hiftory of Seibourne, was wit- 
nefs to a cat's fuckling a young hare, which followed her about 
the garden, and came jumping to her call of affection. At El- 
ford, near Litchfield, the Rev. Mr. Sawley had taken the young 
ones out of a hare, which was fhot ; they were alive, and the 
cat, who had juft loft her own kittens, carried them away, as it 
was fuppofed, to eat them ; but it prcfently appeared, that it 
was a flection not hunger which incited her, as fhe fuckied 
them, and brought them up as their mother. 
Other inftances of the miftaken application of what has been 
termed inftimT may be obferved in flies in the night, who mif- 
taking a candle for day-light, approach and perifh in the flame. 
So the putrid fmell of the ftapelia, or carrion-flower, allures the 
large flefh-fly to depofit its young worms on its beautiful petals, 
which perifh there for want of nouriihment. This therefore 
cannot be a neceflary inftinct, becaufe the creature miftakes the 
application of it. 
Vol. I. R Though 122 
OF INSTINCT. 
Sect. XVI. n. n 
Though in this country horfes (hew little veftiges of policy, 
yet in the deferts of Tartary, and Siberia, when hunted by the 
Tartars they are feen to form a kind of community, fet watch- 
es to prevent their being furprifed, and have commanders, who 
direct, and haften their flight, Origin of Language, Vol. I. p. 
212. In this country, where four or five horfes travel in a line, 
the firft always points his ears forward, and the laft points his 
backward, while the intermediate ones feem quite carelefs in this 
refpeft ; which feems a part of policy to prevent furprife. As 
all animals depend moft on the ear to apprize them of the ap- 
proach of danger, the eye taking in only half the horizon at 
once, and horfes poflefs a great nicety of this fenfe ; as appears 
from their mode of fighting, mentioned No. 8. 5. of this Sec- 
tion, as well as by common obfervation. 
There are fome parts of a horfe, which he cannot conveni- 
ently rub, when they itch, as about the fhoulder, which he can 
neither bite with his teeth, nor fcratch with his hind foot; 
when this p^rt itches, he goes to another horfe, and gently bites 
him in the part which he wifhes to be bitten, which is imme- 
diately done by his intelligent friend. I once obferved a young 
foal thus bite its large mother, who did not choofe to drop the 
grafs flie had in her mouth, and rubbed her nofe againft the 
foal's neck inftead of biting it ; which evinces that the knew 
the defign of her progeny, and was not governed by a neceflary 
inftintt to bite where fhe was bitten. 
Many of our fhrubs, which would otherwife afford an agree- 
able food to horfes, are armed with thorns or prickles, which 
fecure them from thofe animals ; as the holly, hawthorn, goofe- 
berry, gorfe. In the extenfive moorlands of Staffordfhire, the 
horfes have learnt to (lamp upon a gorfe-buffi with one of their 
forefeet for a minute together, and when the points are broken, 
they eat it without injury. The horfes in the new foreft in 
Hampibire are affirmed to do the fame by Mr. Gilpin. Foreft 
Scenery, II. 251, and 112. Which is an art other horfes in the 
fertile parts of the country do not poflefs, and prick their mouths 
till they bleed, if they are induced by hunger or caprice to at- 
tempt eating gorfe. 
Swine have a fenfe of touch as well as of fmell at the end of 
their nofe, which they ufe as a hand, both to root up the foil, 
and to turn over and examine objects of food, fomewhat like the 
probofeis of an elephant. As they require (belter from the 
cold in this climate, they have learnt to collect ftraw in their 
mouths to make their neft, when the wind blows cold ; and to 
call their companions by repeated cries to affift in the work, and 
■add to their warmth by their numerous bed«fellows. Hence 
thefe Sect. XVI. 11. 1. 
OF INSTINCT. 
123 
thefe animals, which are efteemed fo unclean, have alfo learned 
never to befoul their dens, where they have liberty, with their 
own excrement ; an art, which cows and horfes, which have 
open hovels to run into, have never acquired. I have obferved 
great fagacity in fwine ; but the fhort lives we allow them, and 
their general confinement, prevents their improvement, which 
might probably be otherwife greater than that of dogs. 
Inftances of the fagacity and knowledge of animals are very 
numerous to every cbferver, and their docility in learning vari- 
ous arts from mankind, evinces that they may learn fimilar arts 
from their own fpecies, and thus be poflefled of much acquired 
and traditional knowledge. 
A dog whofe natural prey is fheep, is taught by mankind, not 
only to leave them unmolefted, but to guard them ; and to hunt, 
to fet, or to deftroy other kinds of animals, as birds, or vermin ; 
and in fome countries to catch fifh, in others to find truffles, 
and to pra&ife a great variety of tricks ; is it more furprifing 
that the crows fhould teach each other, that the hawk can catch 
lefs birds, by the fuperior fwiftnefs of his wing, and if two of 
them follow him, till he fucceeds in his defign, that they can 
by force fhare a part of the capture ? This I have formerly ob- 
ferved with attention and aftonifhment. 
There is one kind of pelican mentioned by Mr. Ofbeck, one 
of Linnseus's travelling pupils (the pelicanus aquilus), whofe 
food is fifh ; and which it takes from other birds, becaufe it is 
not formed to catch them itfelf ; hence it is called by the Eng- 
lifh a Man-of-war-bird, Voyage to China, p. 88. There are 
many other interefting anecdotes of the pelican and cormorant, 
collected from authors of the beft authority, in a well-managed 
Natural Hiftory for Children, publifhed by Mr. Galton. John- 
fon. London. 
And the following narration from the very accurate Monf. 
Adanfon, in his voyage to Senegal, may gain credit with the read- 
er : as his employment in this country was folely to make ob- 
fervations in natural hiftory. On the river Niger, in his road to 
the iflandGrieljhe faw agreat numberof pelicans, or wide throats. 
" They moved with great Rate like fwans upon the water, and 
are the largeft bird next to the oftrich ; the bill of the one I kill- 
ed was upwards of a foot and half long, and the bag fattened 
underneath it held two and twenty pints of water. They fwim 
in flocks, and form a large circle, which they contract afterwards, 
driving the fifh before them with their legs: when they fee the 
fifh in fufficient number confined in this fpace, they plunge 
their bill wide open into the water, and Ihut it again with great 
quicknefs. 124 
OF INSTINCT. 
Sect. XVI. 12. r. 
quicknefs. They thus get fiTh into their throat-bag, which they 
eat afterwards on fhore at their leifure." P. 247. 
Another curious effort of defign, or ufe of means in animals, 
is related by Abbe Grofier, in his Defcription of China, Vol. I. 
p. 562. A kind of tiger is feen in China, which has a body 
like a dog, but no tail, and is remarkably fwift and ferocious. 
If any one meets this animal, and to efcape from his fury climbs 
up a tree, the tiger immediately fends forth a loud yell, and feveral 
other tigers arrive ; which altogether dig up the earth round the 
roots of the tree, and overturning it, feize their prey. 
The rattlefnake and black ferpent of America alfo fhould here 
be mentioned, which are fuppofed to poflefs an inftin€tive pow- 
er of fafeinating birds ; as many birds have been feen repeatedly 
to run to them and to retreat from them with piteous fcreams, 
till the fnake has feized and devoured them. I formerly fuf- 
pefted, that this ferpent had hid himfelf in the bullies, and had 
iecretly wounded the bird, and followed it with his fteady eye, 
till the poifon inftilled into the wound had time to take efFedf; 
and that the bird then fell from the tree into his mouth. But 
from an ingenious paper, which Dr. B. S. Barton, Profeflbr 
of Natural Hiftory in Pennfylvania, has favoured me with, and 
which will be publifhed in their Philofophical Tran factions, it 
is clearly (hewn, that this piteous cry, and approach, and retreat, 
of the bird fuppofed to be fafeinated is Amply an attack made 
by the female bird on the ferpent in defence of her young ; 
which credulity and the love of admiration has converted into a 
prodigy of fafeination, which is Rill credited by the multitude 
in America. This circumflance of the mother bird daring to 
defend her young from a ferpent, till Ihe was devoured by him, 
and her fcreaming around him, is defcribed by that great ob- 
ferver of nature, the immortal Homer, above 2000 years ago. 
Iliad. Lib. 2. 1. 310. 
XII. The knowledge and language of thofe birds, that fre- 
quently change their climate with the feafons, is Rill more ex- 
tenfive : as they perform thefe migrations in large focieties, and 
are lefs fubject to the power of man, than the refident tribes of 
birds. They are faid to follow a leader during the day, who is 
occafionally changed, and to keep a continual cry during the 
night to keep themfelves together. It is probable that thefe 
emigrations were at firR undertaken as accident directed, by the 
more adventurous of their fpecies, and learned from one another 
like the difeoveries of mankind in navigation. The following 
circumftances Rrongly fupport this opinion. 
1. Nature has provided thefe animals, in the climates where 
they are produced, with another refource, when the feafon be- 
comes Sect. XVI. 12. 2. 
OF INSTINCT. 
125 
comes too cold for their conftitutions, or the food they were fup- 
ported with ceafes to be fupplied : I mean that of fleeping. 
Dormice, fnakes, and bats, have not the means of changing their 
country; the two former from the want of wings, and the lat- 
ter from his being not able to bear the light of the day. Hence 
thefe animals are obliged to make ufe of this refourcc, and fleep 
<luring the winter. And thofe fwallows that have been hatched 
too late in the year to acquire their full ftrength of pinion, or that 
have been maimed by accident or difeafe, have been frequently 
found in the hollows of rocks on the fea coafts, and even under 
water in this torpid ftate, from which they have been revived 
by the warmth of a fire. This torpid ftate of fwallows is tefti- 
fied by innumerable evidences both of ancient and modern 
names. Ariftotle fpeaking of the fwallows fays, " They pafs 
into warmer climates in winter, if fuch places are at no great 
diftance ; if they are, they bury themfelves in the climates where 
they dwell," (8. Hift. c. 16. See alfo Derham's Phyf. TheoL 
v. ii. p. 177.) 
The hybernation of animals is mentioned by M. Fabricius, 
who fuppofes it only to happen to animals, which originally be- 
longed to a warmer climate, and adds, that when thefe ammaU 
are carried back to a warmer climate, and fupplied plentifully 
with food, they ceafe to hybernate. 
Hence their emigrations cannot depend on a necejjary inftincl, 
as the emigrations themfelves are not neceJTary. 
2. When the weather becomes cold, the fwallows in the 
neighbourhood aflemble in large flocks; that is, the unexperi- 
enced attend thofe that have before experienced the journey they 
are about to undertake: they are then feen fome time to hover 
on the coaft, till there is calm weather, or a wind, that fuits the 
direction of their flight. Other birds of pafiage have been 
drowned by thoufands in the fea, or have fettled on (hips quite 
exhaufted with fatigue. And others, either by miftaking their 
courfe, or by diftrefs of weather, have arrived in countries where 
they were never feen before: and thus are evidently fubjeCt to 
the fame hazards that the human fpecies undergo, in the execu- 
tion of their artificial purpofes. 
3. The fame birds are emigrant from fome countries and not 
fo from others: the fwailows were feen at Goree in January by 
an ingenious philofopher of my acquaintance, and he was told 
that they continued there all the year; as the warmth of the cli- 
mate was at all feafons fufficient for their own conftitutions, and 
for the production of the flies that fupply them with nourifli- 
ment. Herodotus fays, that in Libya, about the fprings of the 
Nile, the fwallows continue all the year. (L. 2) 
Quails 126 
OF INSTINCT. 
Sect. XVI. 12. 3. 
Quails (tetrao coturnix, Lin.) are birds of paflage from the 
coaft of Barbary to Italy, and have frequently fettled in large 
{hoals on (hips fatigued with their flight. (Ray, Wifdom of 
God, p. 129. Derham Phyfic. Theol. v. ii. p. 178.) Dr. Ruf- 
fel, in his hiftory of Aleppo, obferves that the fwallows vifit that 
country about the end of February, and having hatched their 
young difappear about the end of July; and returning again 
about the beginning of October, continue about a fortnight, and 
then again difappear. (P. 70.) 
When my late friend Dr. Chambres of Derby was on the 
ifland of Caprea in the bay of Naples, he was informed that great 
flights of quails annually fettle on that ifland about the begin- 
ning of May, in their paflage from Africa to Europe. And that 
they always come when the fouth-eaft wind blows, are fatigued 
when they reft on this ifland, and are taken in fuch amazing 
quantities and fold to the Continent, that the inhabitants pay 
the bilhop his ftipend out of the profits arifing from the fale of 
them. 
The flights of thefe birds acrofs the Mediterranean are record- 
ed near three thoufand years ago. " There went forth a wind 
from the Lord and brought quails from the fea, and let them fall 
upon the camp, a day's journey round about it, and they were 
two cubits above the earth," (Numbers, chap. ii. ver. 31.) 
In our country, Mr. Pennant informs us, that fome quails 
migrate, and others only remove from the internal parts of the 
ifland to the coafts, (Zoology, oifftavo, 210.) Some of the ring- 
doves and ftares breed here, others migrate, (ibid. 510, 511.) 
And the flender billed fmall birds do not all quit thefe kingdoms 
in the winter, though the difficulty of procuring the worms and 
infects, that they feed on, fupplies the fame reafon for migra- 
tion to them all, (ibid. 511.) 
Linnaeus has obferved, that in Sweden the female chaffinches 
quit that country in September, migrating into Holland, and 
leave their mates behind till their return in fpring. Hence he 
has called them Fringiila caelebs, (Amaen. Acad. ii. 42. iv. 595•) 
Now in our climate both fexes of them are perennial birds. And 
Mr. Pennant obferves that the hoopoe, chatterer, hawfinch, and 
crofs-bill, migrate into England fo rarely, and at fuch uncertain 
times, as not to deferve to be ranked among our birds of paf- 
fage, (Zool. 8vo. 511.) 
The water fowl, as geefe and ducks, are better adapted for 
long migrations, than the other tribes of birds, as, when the 
weather is calm, they can not only reft themfelves, or fleep upon 
the ocean, but poffibly procure fome kind of food from it. 
Hence in Siberia, as foon as the lakes are frozen, the water 
fowl. Sect. XVI. 12. 3. 
OF INSTINCT. 
127 
fowl, which are very numerous, all difappear, and are fuppofed 
to fly to warmer climates, except the rail, which, from its inabil- 
ity for long flights, probably fleeps, like our bat, in their winter. 
The following account from the Journey of Profeflbr Gmelin, 
may entertain the reader. " In the neighbourhood of Krafnoi- 
ark, amongft many other emigrant water fowls we obferved a 
great number of rails, which when purfued never took flight, 
but endeavoured to efcape by running. We inquired how thefe 
birds, that could not fly, could retire into other countries in the 
winter, and were told, both by the Tartars and Aflanians, that 
they well knew thofe birds could not alone pafs into other coun- 
tries: but when the cranes (les grues) retire in autumn, each one 
takes a rail (un rale) upon his back, and carries him to a warmer 
climate." 
Recapitulation. 
i. AH birds of paflage can exift in the climates, where they 
are produced. 
2. They are fubjeft in their migrations to the fame accidents 
and difficulties, that mankind are fubjedt to in navigation. 
3. The fame fpecies of birds migrate from fome countries, 
and are refident in others. 
From all thefe circumftances it appears that the migrations of 
birds are not produced by a neceflary inftinft, but are acciden- 
tal improvements, like the arts among mankind, taught by their 
contemporaries, or delivered by tradition from one generation 
of them to another. 
XIII. In that feafon of the year which fupplies the nouriffi- 
ment proper for the expedbed brood, the birds enter into a con- 
trail of marriage, and with joint labour conftruil a bed for the 
reception of their offspring. Their choice of the proper feafon, 
their contrails of marriage, and the regularity with which they 
conftrudb their nefts, have in all ages excited the admiration of 
naturalifts ; and have always been attributed to the power of in- 
ftinit, which, like the occult qualities of the ancient philofo- 
phers, prevented all further inquiry. We fhall confider them 
in their order. 
'Their Choice of the Seafon. 
Our domeftic birds, that are plentifully fupplied throughout 
the year with their adapted food, and are cdvered with houfes 
from the inclemency of the weather, lay their eggs at any fea- 
fon : which evinces that the fpring of the year is not pointed 
out to them by a neceflary inftindt 
Whilft 128 
OF INSTINCT. 
Sect. XVI. 13. n 
Whihl the wild tribes of birds choofe this time of the year 
from their acquired knowledge, that the mild temperature of the 
air is more convenient for hatching their eggs, and is foon likely 
to fupply that kind of nourifhment, that is wanted for their young. 
If the genial warmth of the fpring produced the paffion of 
love, as it expands the foliage of trees, all other animals ihould 
feel its influence as well as birds : but, the viviparous creatures, 
as they fucklc their young, that is, as they previoufly digelt the 
natural food, that it may better fuit the tender ftomachs of their 
offspring, experience the influence of this paflion at all feafons 
of the year, as cats and bitches.. The graminivorous animals 
indeed generally produce their young about the time when grafs 
is fupplied in the greateft plenty, but this is without any degree 
of exattnefs, as appears from our cows, fheep, and hares, and 
may be a part of the traditional knowledge, which they learn 
from the example of their parents. 
Their Contracis of Marriage. 
Their mutual paflion, and the acquired knowledge, that their 
joint labour is neceflary to procure fuftenance for their numer- 
ous family, induces the wild birds to enter into a contrail of 
marriage, which does not however take place among the ducks, 
geefe, and fowls, that are provided with their daily food from 
our barns. 
An ingenious philofopher has lately denied, that animals can 
enter into contrails, and thinks this an effential difference be- 
tween them and the human creature :-but does not daily ob- 
fervation convince us, that they form contrails of friendlhip 
with each other, and with mankind ? When puppies and kittens 
play together, is there not a tacit contrail, that they will not 
hurt each other ? And does not your favourite dog expeil you 
Ihould give him his daily foodj for his fervices and attention to 
you ? And thus barters his love for your proteilion ? In the 
fame manner that all contrails are made amonglt men, that do 
not underftand each other's arbitrary language. 
The Conjltuclion of their Nefs. 
i. They feem to be inftrudled how to build their nefts from 
their obfervation of that, in which they were educated, and from 
their knowledge of thole things, that are moft agreeable to their 
touch in refpecl to warmth, cleanlinefs, and liability. They 
choofe their fituations from their ideas of fafety from their ene- 
mies, and of Ihelter from the weather. Nor is the colour of 
their Sect. XVI. 13. 2. 
OF INSTINCT. 
129 
their nefts a circumftance unthought of; the finches, that build 
in green hedges, cover their habitations with green mofs ; the 
fwallow or martin, that builds againft rocks and houfes, covers 
hers with clay, whilft the lark choofes vegetable ftraw nearly of 
the colour of the ground (he inhabits: by this contrivance, they 
are all lefs liable to be difcovered by their adverfaries. 
2. Nor are the nefts of the fame fpecies of birds conftrufted 
always of the fame materials, nor in the fame form ; which is 
another circumftance that afcertains, that they are led by obfer- 
vation. 
In the trees before Mr. Levet's houfc in Litchfield, there are 
annually nefts built by fparrows, a bird which ufually builds un- 
der the tiles of houfes, or the thatch of barns. Not finding fuch. 
convenient fituations for their nefts, they build a covered nelt 
bigger than a man's head, with an opening like a mouth at the 
fide, refembling that of a magpie, except that it is built with, 
ftraw and hay, and lined with feathers, and fo nicely managed 
as to be a defence againft both wind and rain. 
The following extraCt from a Letter of the Rev. Mr. J. Dar- 
win, of Carleton Scroop in Lincolnihire, authenticates a curious 
faCt of this kind. " When I mentioned to you the circum- 
ftance of crows or rooks building in the fpire of Welbourn 
church, you exprefled a defire of being well informed of the 
certainty of the faCt. Welbourn is fituated in the road from 
Grantham to Lincoln on the Cliff' row; I yefterday took a ride 
thither, and inquired of the redor, Mr. Ridgehill, whether the 
report was true, that rooks built in the fpire of his church. He 
allured me it was true, and that they had done fo time imme- 
morial, as his parilhioners affirmed. There was a common tra- 
dition, he faid, that formerly a rookery in feme high trees ad- 
joined the church yard, which being cut down (probably in the 
fpring, the building feafon), the rooks removed to the church, 
and built their nefts on the outfide of the fpire on the tops of 
windows, which by their projection a little from the fpire made 
them convenient room, but that they built alfo on the infide. I 
faw two nefts made with fticks on the outfide, and in the fpires, 
and Mr. Ridgehill faid there were always a great many. 
" I fpent the day with Mr. Wright, a clergyman, at Fulbeck, 
near Welbourn, and in the afternoon Dr. Ellis of Leadenham, 
about two miles from Welbourn, drank tea at Mr. Wright's, who 
faid he remembered, when Mr. Welby lived at "Welbourn, that 
he received a letter from an acquaintance in the weft of Eng- 
land, defiring an anfwer, whether the report of rooks building 
in Welbourn church was true, as a wager was depending on 
Vol. I. S that 130 
OF INSTINCT. 
Sect. XVI. 13. 2^ 
that fubjeft; to which he returned an anfwer afcertaining the 
fa ft, and decided the wager." Aug. 30, 1794. 
So the jackdaw (corvus monedula) generally builds in church 
fteeples, or under the roofs of high houfes ; but at Seibourn, in 
Sourhamptonlhire, where towers and fteeples are-not fufficiently 
numerous, thefe birds build in forfaken rabbit burrows. See a 
curious account of thefe fubterranean nefts in White's Hiftory 
of Seibourn, p. 59. Can the fkilful change of architecture in 
thefe birds and the fparrows above mentioned be governed by 
inftinCt ? Then they mu ft have two inftinfts, one for common, 
and the other for extraordinary occafions. 
I have feen green worfted in a neft, which no where exifts in 
nature : and the down of thiftles in thofe nefts, that were by 
fome accident conftrucbed later in the fummer, which material 
could not be procured for the earlier nefts : in many different 
climates they cannot procure the fame materials, that they ufe in 
ours. And it is well known, that the canary birds, that are prop- 
agated in this country, and the finches, that are kept tame, will 
build their nefts of any flexile materials, that are given them. 
Plutarch, in his Book on Rivers, fpeaking of the Nile, fays, 
" that the fwallows collect a material, when the waters recede, 
with which they form nefts, that are impervious to water." And 
in India there is a fwallow that coileCls a glutinous fubftance 
for this purpofe, whole neft is efculent, and efteemed a princi- 
pal rarity amongft epicures, (Lin. Syft. Nat.) Both thefe muftbe 
eonftrucled of very different materials from thofe ufed by the 
fwallows of our country. 
In India the birds exert more artifice in building their nefts on 
account of the monkeys and fnakes: fome form their pen file 
nefts in the fliape of a purfe, deep and open at top ; others with 
a hole in the fide; and others, ftill more cautious, with an en- 
trance at the very bottom, forming their lodge near the fummit. 
But the taylor-bird will not even truft its neft to the extremity 
of a tender twig, but makes one more advance to fafety by fix- 
ing it to the leaf itfelf. It picks up a dead leaf, and fews it to 
the fide of a living one, its (lender bill being its needle, and its 
thread fome fine fibres ; the lining confifts of feathers, goflamer, 
and down ; its eggs are white, the colour of the bird light yel- 
low, its length three inches, its weight three fixteenths of an 
ounce ; fo that the materials of the neft, and the weight of the 
bird, arc not likely to draw down an habitation fo Rightly fuf- 
pended. A neft of this bird is preferred in the Britilh Mufe- 
um, (Pennant's Indian Zoology.) This calls to one's mind the 
Mofaic account of the origin of mankind, the firft dawning of 
art there aferibed to them, is that of fewing leaves together. 
For Sect. XVI. 13. 3. 
OF INSTINCT. 
131 
For many other curious kinds o£ nefts fee Natural Hiftory for 
Children, by Mr. Galton. Johnfon. London. Part I. p. 47. 
Gen. Oriolus. 
3. Thofe birds that are brought up by our care, and have had 
little communication with others of their own fpecies, are very 
defective in this acquired knowledge; they are not only very 
awkward in the conftrucftion of their nefts, but generally fcatter 
their eggs in various parts of the room or cage, where they are 
confined, and feldom produce young ones, till, by failing in their 
£rft attempt, they have learnt fomething from their own obfer- 
vation. 
4. During the time of incubation birds are faid in general to 
turn their eggs every day; fome cover them, when they leave 
the neft, as ducks an'l geefe; in fome the male is faid to bring 
food to the female, that fhe may have lefs occafion of abfence, 
in others he is faid to take her place, when (lie goes in queft of 
food ; and all of them are faid to leave their eggs a (hotter time 
in cold weather than in warm. In Senega! the oftrich fits on 
her eg"S only during the night, leaving them in the day to the 
heat of the fun ; but at the Cape of Good Hope, whete the heat 
is lefs, (he fits on them day and night. 
If it (hould be afked, what induces a bird to fit weeks on its 
firft eggs unconfcious that a brood of young ones will be the 
product ? The anfwer muft be, that it is the fa^^adion that 
induces the human mother to hold her offspring Whole nights 
and days in her fond arms, and prefs it to her bofom, uncon- 
fcious of its future growth to fenfe and manhood, till obferva- 
tion or tradition have informed her. 
5. And as many ladies are too refined to nurfe their own 
children, and deliver them to the care and prcvifion of others ; 
fo is there one inftance of this vice in the feathered world. The 
cuckoo in fome parts of England, as I am well informed by a 
very diftimS! and ingenious gentleman, hatches and educates her 
young whilft in other parts (he builds no neft, but ufes that of 
fome lefler bird, generally either of the wagtail, or hedge fpar- 
row, and depofiting one egg in it, takes no further care of her 
progeny. 
M. Heriflant thought, that he had difcovered the reafon, why 
cuckoos do not incubate their own eggs, by having obferved that 
the crop or ftomach of the cuckoo was placed behind the fter- 
num, or breaft-bone, and he thence fancied, that this would 
render incubation difagreeable or impracticable. Hift. de 1' 
Acad. Royal. 1752. But Mr. White, in his Natural Hiftory of 
Seibourn afierts, that on diffefting a fern-owl he found the fitu- 
ation of the crop or ftomach of that bird to be behind the fter- 
num, 132 
OF INSTINCT. 
Sect. XVI. 13. 
num, like that of the cuckoo, and fuppofes that many other 
birds may be organized in the fame manner. And, as the fern- 
owl incubates and hatches her own eggs, he rationally concludes, 
that this ftruclure of the bird cannot be the caufe of her want 
of maternal ftorge. Hift. of Seibourn, p. 208. 
As the Rev. Mr. Stafford was walking in Glofop Dale, in the 
Peak of Derbyfhire, he faw a cuckoo rife from its neft. The 
neft was on the flump of a tree, that had been fome time felled, 
among fome chips that were in part turned grey, fo as much to 
refemble the colour of the bird; in this neft were two young 
cuckoos: tying a firing about the leg of one of them, he peg- 
ged the other end of it to the ground, and very frequently for 
many days beheld the old cuckoo feed thefe young, as he flood 
very near them. 
The following extraCi of a Letter from the Rev. Mr. Wilmot, 
of Morley, near Derby, flrengthens the truth of the fact above 
mentioned, of the cuckoo fometimes making a neft, and hatch- 
ing her own young. 
"In the beginning of July 1792, I was attending fome la- 
bourers on my farm, when one of them faid to me, " There is 
a bird's neft upon one of the Coal-flack Hills; the bird is now 
fitting, and is exactly like a cuckoo. They fay that cuckoos 
never hatch their own eggs, other wife I fhould have fworn it 
was one." He took me to the fpot, it was in an open fallow 
ground; the bird was upon the neft, I flood and obferved her 
fome time, and was perfectly fatisfied it was a cuckoo ; I then 
put my hand towards her, and the almoft let me touch her be- 
fore flie rofe from the neft, which the appeared to quit with great 
uneafinefs, fkimming over the ground in the manner that a hen 
partridge does when diflurbed from a new hatched brood, and 
went only to a thicket about forty or fifty yards from the neft; 
and continued there as long as I ftaid to obterve her, which was 
not many minutes. In the neft, which was barely a hole fcratch- 
ed out of the coal flack in the manner of a plover's neft, 1 ob- 
ferved three eggs, but did not touch them. As Lhad labourers 
conftantly at work in that field, I went thither every day, and al- 
ways looked to fee if the bird was there, but did not difturb her 
for feven or eight days, when I was tempted to drive her from 
the neft, and found two young ones, that appeared to have been 
hatched fome days, but there was no appearance of the third egg. 
I then mentioned this extraordinary circumftance (for fuch I 
thought it) to Mr. and Mrs. Holyoak of Bidford Grange, War- 
wickfhire, and to Mifs M. Willes, who were on a vifit at my 
houfe, and who all went to fee it. Very lately I reminded Mr. 
Holyoak of it, who told me he had a perfect recollection of 
*'. the Sect. XVI. 14. n 
OF INSTINCT. 
133 
the whole, and that, confidering it a curiofity, he walked to 
look at it feveral times, was perfectly fatisfied as to its being a 
cuckoo, and thought her more attentive to her young, than any 
other bird he ever obferved, having always found her brooding 
her young. In about a week after I firth faw the young ones, 
one of them was miffing, and I rather fufpethed my plough-boys 
having taken it; though it might poffibly have been taken by a 
hawk, fometime when the old one was feeking food. I never 
found her off her neft but once, and that was the laft time I faw 
the remaining young one, when it w^ almoft full feathered. I 
then went from home for two or three days, and, when I return- 
ed, the young one was gone, which I take for granted had flown. 
Though during this time I frequently faw cuckoos in the thick- 
et I mention, I never obferved any one, that I fuppofed to be the 
cock-bird, paired with this hen." 
Nor is this a new obfervation, though it is entirely overlooked 
by the modern naturalifts, for Ariftotle fpeaking of the cuckoo, 
afferts that ffie fometimes builds her neft among broken rocks, 
and on high mountains, (L. 6. H. c. i.) but adds in another 
place that fhe generally poffefles the neft of another bird, (L. 6. 
H. c. 7.) And Niphus fays that cuckoos rarely build for them- 
felves, moft frequently laying their eggs in the nefts of other 
birds, (Gefner, L. 3. de Cuculo.) 
The Philofopher who is acquainted with thefe facts concern- 
ing the cuckoo, would feem to have very little reafon himfelf, if 
he could imagine this neglect of her young to be a neceffary 
inJiinci I 
XIV. The deep receffes of the ocean are inacceffible to man- 
kind, which prevents us from having much knowledge of the 
arts and government of its inhabitants. 
1. One of the baits ufed by the fiffierman is an animal called 
an Old Soldier; his fize and form are fomewhat like the craw- 
fiffi, with this difference, that his tail is covered with a tough 
membrane inftead of a (hell; and to obviate this defedt, he feeks 
out the uninhabited (hell of fome dead fifh, that is large enough 
to receive his tail, and carries it about with him as part of his 
clothing or armour. 
2. On the coafts about Scarborough, where the haddocks, 
cods, and dog-fifh, are in great abundance, the fifhermen univer- 
fally believe that the dog-fifh make a line, or femicircle, to en- 
compafs a fhoal of haddocks and cod, confining them within 
certain limits near the fliore, and eating them as occafion re- 
quires. For the haddocks and cod are always found near the 
Ihore without any dog-fiih among them, and the dog-fiih further 
off without any haddocks or cod ; and yet the former are known 
to 134 
OF INSTINCT. 
Sect. XVI. 14. 3. 
to prey upon the latter, and in feme years devour fuch immenfe 
quantities as to render this fiihery more expenfive than profita- 
ble. 
3. The remora, when he wifhes to remove his fituation, as 
he is a very flow fwimmer, is content to take an outfide place 
on whatever conveyance is going his way; nor can the cunning 
animal be tempted to quit his hold of a fhip when fhe is failing, 
not even for the lucre of a piece of pork, left it fhould endan- 
ger the lofs of his paflage : at other times he is eafily caught with 
the hook. 
4. The crab-fifh, like many other teftaceous animals, annu- 
ally changes its fhcll; it is then in a foft ftate, covered only 
with a mucous membrane, and conceals itfelf in holes in the 
fand or under weeds ; at this place a hard fhelled crab always 
ftands centinel, to prevent the fea infers from injuring the other 
in its defencelefs ftate; and the fifhermen from his appearance 
know where to find the foft ones, which they ufe for baits in 
catching other fifh. 
And though the hard fhelled crab, when he is on this duty, 
advances boldly to meet the foe, and will with difficulty quit 
the field; yet at other times he fhews great timidity, and has a 
wonderful fpeed in attempting his efcape ; and, if often inter- 
rupted, will pretend death like the fpider, and watch an oppor- 
tunity to fink himfelf into the fand, keeping only his eyes above. 
My ingenious friend Mr. Burdett, who favoured me with thefe 
accounts at the time he was furveying the coafts, thinks the 
commerce between the fexes takes place at this time, and in- 
fpires the courage of the creature. 
5. The Ihoals of herrings, cods, haddocks, and other fifh, 
which approach our fhores at certain feafons, and quit them at 
other feafons without leaving one behind ; and the falmon, that 
periodically frequent our rivers, evince, that there are vagrant 
tribes of filh, that perform as regular migrations as the birds of 
pailage already mentioned. 
6. There is a cataract on the river Liffey in Ireland about 
nineteen feet high : here in the falmon feafon many of the inhab- 
itants amufe themfelves in obferving thefe fifh leap up the tor- 
rent. They dart themfelves quite out of the Water as they af- 
cend, and frequently fall back many times before they furmount 
it, and bafkets made of twigs are placed near the edge of the 
ftream to catch them in their fall. 
I have obferved, as I have fat by a fpout of water, which de- 
scends from a ftone trough about two feet into a ftream below, 
at particular feafons of the year, a great number of little filh 
called miliums, or pinks, throw themfelves about twenty times 
their Sect. XVI. 15. i» 
OF INSTINCT. 
135 
their own length out of the water, expelling to get into the 
trough above. 
This evinces that the ftorge, or attention of the dam to pro- 
vide for the offspring, is ftrongly exerted amongft the nations 
of filh, where it would feem to be the moft neglected ; as thefe 
falmon cannot be fu^pofed to attempt fo difficult and dangerous 
a talk without being confcious of the purpofe or end of their en- 
deavours. 
It is further remarkable, that moft of the old falmon return 
to the fea before it is proper for the young fhoals to attend them, 
yet that a few old ones continue in the^ivers fo late, that they 
become perfectly emaciated by the inconvenience of their fitu- 
ation, and this apparently to guide or to protect the unexperi- 
enced brood. 
Of the fmaller water animals we have Rill lefs knowledge, 
who neverthelefs probably poffefs many fuperior arts ; feme of 
thefe are mentioned in Botanic Garden, P.L Add. Note XXVII. 
and XXVIII. The nymphae of the water-moths of our rivers, 
which cover themfclves with cafes of ftraw, gravel, and (hell, 
contrive to make their habitations nearly in equilibrium with 
the water; when too heavy, they add a bit of wood or ftraw ; 
when too light, a bit of gravel. Edinb. Tranf. 
All thefe circumftances bear a near refemblance to the delib- 
erate actions of human reafon. 
XV. We have a very imperfect acquaintance with the vari- 
ous tribes of infeRs: their occupations, manner of life, and even 
the number of their fenfes, differ from our own, and from each 
other ; but there is reafon to imagine, that thofe which poflefs 
the fenfe of touch in the moft exquifite degree, and whofe oc- 
cupations require the moft conftant exertion of their powers, 
are endued with a greater proportion or knowledge arid inge- 
nuity. 
The fpiders of this country manufacture nets of various 
forms, adapted to various fituations, to arreft the flies that are 
their food ; and fome of them have a houfe or lodging-place in 
the middle of the net, well contrived for warmth, fecurity, or 
concealment. There is a large fpider in South America, who 
conftrudls nets of fo ftrong a texture as to entangle fmall birds, 
particularly the humming bird. And in Jamaica there is an- 
other fpider, who digs a hole in the earth obliquely downwards, 
about three inches in length, and one inch in diameter ; this 
cavity file lines with a tough thick web, which when taken out 
refembles a leathern purfe : but what is moft curious, this houfe 
has a door with hinges, like the operculum of feme fea (hells ; 
and herfelf and family, who tenant this neft, open and (but the 
door. 136 
OF INSTINCT. 
Sect. XVI. ia 
door, whenever they pafs or repafs. This hiftory was told me, 
and the neft with its operculum (hewn me by the late Dr. Butt 
of Bath, who was feme years phyfician in Jamaica. 
The production of thefe nets is indeed a part of the nature 
or conformation of the animal, and their natural ufe is to fup- 
ply the place of wings, when fhe withes to remove to another 
fituation. But when flic employs them to entangle her prey, 
there are marks of evident defign, for fhe adapts the form of 
each net to its fituation, and rtrengthens thofe lines, that require 
it, by joining others to the middle of them, and attaching thofe 
others to dirtant objects, with the fame individual art, that is 
ufed by mankind in fupporting the marts and extending the 
fails of (hips. This work is executed with more mathematical 
exadtnefs and ingenuity by the held fpiders, than by thofe in 
our houfes, as thoir conftrudtions are more fubjedted to the in- 
juries of dews and tempefts. 
Befides the ingenuity {hewn by thefe little creatures in taking 
their prey, the circumftance of their counterfeiting death, when 
they are put into terror, is truly wonderful ; and as foon as the 
object of terror is removed, they recover and run away. Some 
beetles are alfo faid to poffefs this piece of hypocrify. 
The curious webs, or cords, conftrudted by fome young cat- 
erpillars to defend themfelves from cold, or from infedts of prey; 
and by filk-worms and fome other caterpillars, when they tranf- 
migrate into aureli?e or larvae, have defervedly excited the admi- 
ration of the inquifitive. But our ignorance of their manner of 
life, and even of the number of their fenfes, totally precludes 
us from underitanding the means by which they acquire this 
knowledge. 
The care of the falmon in choofing a proper fituation for her 
fpawn, the ftrudture of the nefts of birds, their patient incuba- 
tion, and the art of the cuckoo in depofiting her egg in her neigh- 
bour's nurfery, are inftances of great fagacity in thofe creatures : 
and yet they are much inferior to the arts exerted by many of 
the infedt tribes on fimilar occalions. The hairy excrefcences 
on briars, the oak apples, the blarted leaves of trees, and the 
lumps on the backs of cows are fituations that are rather produ- 
ced than chofen by the mother infedt for the ccnvenience of her 
offspring. The cells of bees, wafps, fpiders, and of the various 
coralline infedts, equally aftonilh us whether we attend to the 
materials or to the architecture. 
But the conduct of the ant, and of fome fpecies of the ich- 
neumon fly in the incubation of their eggs, is equal to any exer- 
tion of human feience. The ants many times in a day move 
their eggs nearer the furface of their habitation, or deeper be- 
low Sect. XVI. 16. 1. 
OF INSTINCT. 
137 
low it, as the heat of the weather varies ; and in colder days lie 
upon them in heaps for the purpofe of incubation : if their 
manfion is too dry, they carry them to places where there is 
moifture, and you may diftin&ly fee the little worms move and 
fuck up the water. When too much moifture approaches their 
neft, they convey their eggs deeper in the earth, or to fome oth- 
er place of fafety. (Swammerd. Epil. ad Hift. Infect, p. 153. 
Phil. Tranf. No. 23. Lowthorp. V. 2. p. 7.) 
There is one fpecies of ichneumon-fly, that digs a hole in the 
earth, and carrying into it two or three living caterpillars, de- 
pofits her eggs, and nicely clofing up the neft leaves them there ; 
partly doubtlefs to aflift the incubation, and partly to fupply food 
to her future young, (Derham. B. 4. c. 13. Ariftotle Hift. 
Animal. L. 5. c. 20.) 
A friend of mine put about fifty large caterpillars collected 
from cabbages on fome bran and a few leaves into a box, and 
covered it with gauze to prevent their efcape. After a few 
days we faw, from more than three fourths of them, about eight 
or ten little caterpillars of the ichneumon-fly come out of their 
backs, and fpin each a fmall cocoon of filk, and in a few days 
the large caterpillars died. This fmall fly it feems lays its egg 
in the back of the cabbage caterpillar, which when hatched preys 
upon the material, which is produced there for the purpofe of 
making filk for the future neft of the cabbage caterpillar ; of 
which being deprived, the creature wanders about till it dies, 
and thus our gardens are preferved by the ingenuity of this 
cruel fly. 
This curious property of producing a filk thread, which is 
common to fome fea animals, fee Botanic Garden, Part I. Note 
XXVII. and is defigned for the purpofe of their transformation 
as in the filk-worm, is ufed for conveying themfelves from higher 
branches to lower ones of trees by fome caterpillars, and to make 
themfelves temporary nefts or tents, and by the fpider for en- 
tangling his prey. Nor is it ftrange that fo much knowledge 
fhould be acquired by fuch fmall aninjals; fince there is reafon 
to imagine, that thefe infedls have the fenfe of touch, either in 
their prebofeis, or their antennae, to a great degree of perfec- 
tion ; and thence may poflefs, as far as their fphere extends, as 
accurate knowledge, and as fubtle invention, as the difeovererf 
of human arts. 
XVI. 1. If we were better acquainted with the hiftori.es of 
thofe infefts that are formed into focieties, as the beep, wafps, 
and ants, I make no doubt but we fhould find, that their arts 
and improvements are Jiot fo fimilar and uniform as they now 
appear to us, but that they arofe in the fame manner from ex- 
Vol. I. T perience 138 
OF INSTINCT. 
Sect. XVI. 16. 2. 
perience and tradition, as the arts of our own fpecies ; though 
their reafoning is from fewer ideas, is bufied about fewer objects* 
and is exerted with lefs energy. 
There are fome kinds of infects that migrate like the birds 
before mentioned. The loculi of warmer climates has fome- 
times come over to England ; it is fhaped like a grafshopper, 
with very large wings, and a body above an inch in length. It 
is mentioned as coming into Egypt with an eaft wind, "The 
Lord brought an eaft wind upon the land all that day and night, 
and in the morning the eaft wind brought the locufts, and cov- 
ered the face of the earth, fo that the land was dark," Exod. x. 
13. The migrations of thefe infedts are mentioned in another 
part of the fcripture, " The locufts have no king, yet go they 
forth all of them in bands," Prov. xxx. 27. 
The accurate Mr. AdanGon, near the river Gambia in Africa, 
was witnefs to the migration of thefe infefts. " About eight in 
the morning, in the month of February, there fuddenly arofe 
over our heads a thick cloud, which darkened the air, and de- 
prived us of the rays of the fun. We found it was a cloud of 
locufts raifed about twenty or thirty fathoms from the ground, 
and covering an extent of feveral leagues; at length a fhower of 
thefe infects defeended, and after devouring every green herb, 
while they refted, again refumed their flight. This cloud was 
brought by a ftrong eaft-wind, and was all the morning in pafL 
ing over the adjacent country." (Voyage to Senegal, 158.) 
In this country the gnats are fometimes feen to migrate in 
clouds, like the mufketoes of warmer climates, and our fwarms 
of bees frequently travel many miles, and are faid in North 
America always to fly toward the fouth. The prophet Ifaiah has 
a beautiful allufion to thefe migrations, " The Lord (ball call 
the fly from the rivers of Egypt, and ihall hifs for the bee that is 
in the land of Aflyria," Ifa. vii. 18. which has been lately ex- 
plained by Mr. Bruce, in his Tavels to difeover the Source of 
the Nile. 
2. I am well informed that the bees that were carried into 
Barbadoes, and other weftern iflands, ceafed to lay up any honey 
after the firft year, as they found it not ufeful to them : and are 
now become very troublefome to the inhabitants of thofe iflands 
by infefting their fugar-houfes ; but thofe in Jamaica continue 
to make honey, as the cold north winds, or rainy feafons of that 
ifland, confine them at home for feveral weeks together. And 
the bees of Senegal, which differ from thofe of Europe only in 
fize, make their honey not only fuperior to ours in delicacy of 
flavour, but it has this Angularity, that it never concretes, but 
remains liquid as fyrup, (Adanfon). From feme obfervations of 
Mr. Sect. XVI. 16. 3. 
OF INSTINCT. 
139 
Mr. Wildman, and of other people of veracity, it appears, that 
during the fevere part of the winter feafon for weeks together 
the bees are quite benumbed and torpid from the cold, and do 
not confume any of their provifion. This ftate of fleep, like that 
of fwallows and bats, feems to be the natural refource of thofe 
creatures in cold climates, and the making of honey to be an 
artificial improvement. 
As the death of our hives of bees appears to be owing to their 
being kept fo warm, as to require food when their ftock is ex- 
haufted ; a very obferving gentleman at my requeft put two 
hives for many weeks into a dry cellar, and obferved, during all 
that time, they did not confume any of their provifion, for their 
weight did not decreafe as it had done when they were kept in 
the open air. The fame observation is made in the Annual 
Regifter for 1768, p. 113. And the Rev. Mr. White, in his 
Method of preferving Bees, adds, that thofe on the north fide of 
his houfe confumed lefs honey in the winter than thofe on the 
fouth fide. 
There is another obfervation on bees well afcertained, that 
they at various times, when the feafon begins to be cold, by a 
general motion of their legs as they hang in clutters produce 
a degree of warmth, which is eafily perceptible by the hand. 
Hence by this ingenious exertion, they for a long time prevent 
the torpid ftate they would naturally fall into. 
According to the late obfervations of Mr. Hunter, it appears 
that the bee's-wax is not made from the duft of the anthers of 
flowers, which they bring home on their thighs, but that this 
makes what is termed bee-bread, and is ufed for the purpofe of 
feeding the bee maggots ; in the fame manner butterflies live on 
honey, but the previous caterpillar lives on vegetable leaves, 
while the maggots of large flies require flefh for their food, and 
thofe of the ichneumon fly require infedts for their food. What 
induces the bee who lives on honey to lay up vegetable powder 
for its young ? What induces the butterfly to lay its eggs on 
leaves, when itfelf feeds on honey ? What induces the other flies 
to feek a food for their progeny different from what they con- 
fume themfelves ? If thefe are not deductions from their own 
previous experience or obfervation, all the aClions of mankind 
muft be refolved into inftinCl. 
3. "The dormoufe confumes but little of its food during the 
rigour of the feafon, for they roll themfelves up, or fleep, or lie 
torpid the greateft part of the time ; but on warm funny days 
experience a fhort revival, and take a little food, and then re- 
lapfe into their former ftate." (Pennant Zoolog. p. 67.) Other 
animals that fleep in winter without laying up any provender, 
• are 140 
OF INSTINCT. 
Sect. XVI. 16. 4. 
are obferved to go into their winter beds fat and flrong, but re- 
turn to day light in the fpring feafon very lean and feeble. The 
common flies fleep during the winter without any prcvifion for 
their nourifhmcnt, and are daily revived by the warmth of the 
fun, or of our fires. Thefe whenever they fee light endeavour 
to approach it, having obferved, that by its greater vicinity they 
get free from the degree of torpor that the cold produces; and 
are hence induced perpetually to burn themfelves in our candles : 
deceived, like mankind, by the mifapplication of their knowl- 
edge. Whilfl many of the fubterraneous infetSls, as the com- 
mon worms, feem to retreat fo deep into the earth as not to be 
enlivened or awakened by the difference of our winter days; 
and flop up their holes with leaves or draws, to prevent the 
frofts from injuring them, or the centipes from devouring them. 
The habits of peace, or the flratagems of war, of thefe fubterra- 
nean nations are covered from our view ; but a friend of mine 
prevailed on a diftrefled worm to enter the hole of another worm 
on a bowling-green, and he prefently returned much wounded 
about his head. And I once faw a worm rife haftily out of the 
earth into the fun-fhine, and obferved a centipes hanging at its 
tail : the centipes nimbly quitted the tail, and feizing the worm 
about its middle cut it in half with its forceps, and preyed upon 
one part, while the other efcaped. Which evinces they have 
defign in flopping the mouths of their habitations. 
4. The wafp of this country fixes his habitation underground, 
that he may net be affected with the various changes of our 
climate; but in Jamaica he hangs it on the bough of a tree, 
where the feafons are lefs fevere. He weaves a very curious 
paper of vegetable fibres to cover his neft, which is conflnuSled 
on the fame principle with that of the bee, but with a different 
material ; but as his prey confifls of flefh, fruits, and infects, 
which arc perifhable commodities, he can lay up no provender 
for the winter. 
M. de la Loubiere, in his relation of Siam, fays, " That in a 
part of that kingdom, which lies open to great inundations, all 
the ants make their fettlements upon trees; no ants' nefts are to 
be feen any where elfe." Whereas in our country the ground 
is their only fituation. From the fcriptural account of thefe in- 
fects, one might be led to fufpedl, that in fome climates the lay 
up a provifion for the winter, (Prov. vi. 6. xxx. 25.) Origen af- 
firms the fame, (Cont. Cclf. L. 4.) But it is generally believed 
that in this country they do not. The white ants of the coaft 
of Africa make themfelves pyramids eight or ten feet high, on 
a bafe of about the fame width, with a fmooth furface of rich 
clay, exceffively hard and well built, which appear at a diftance 
like Sect. XVI. 17. 1. 
OF INSTINCT. 
141 
like an aflemblage of the huts of the negroes, (Adanfon). The 
hiltory of thefe has been lately well defcribed in the Philofoph. 
Tranfaifions, under the name of termes, or termites. Thefe 
differ very much from the neft of our large ant; but the real 
hiftory of this creature, as well as of the wafp, is yet very im- 
perfeilly known. 
Wafps are faid to catch large fpiders, and to cut olF their legs, 
and carry their mutilated bodies to their young, Dith Raifon. 
Tom. I. p. 152. 
One circumftance I {hall relate which fell under my own eye, 
and fhewed the power of reafon in a wafp, as it is exerciied 
among men. A wafp, on a gravel walk, had caught a fly nearly 
as large as himfelf; kneeling on the ground I obferved him fep- 
arate the tail and the head from the body part, to which the 
wings were attached. He then took the body part in his 
paws, and rofe about two feet from the ground with it; but a 
gentle breeze wrafting the wings of the fly turned him round in 
the air, and he fettled again with his prey upon the gravel. I 
then diftimflly obferved him cut ofF with his mouth, firfl one of 
the wrings, and then the other, after which he flew away with 
it unmolefted by the wind. 
Go, thou fluggard, learn arts and induftry from the bee, and 
from the ant ! 
Go, proud reafoner, and call the worm thy filler ! 
XVII. Conclujion. 
It was before obferved how much the fuperior accuracy of 
our fenfe of touch contributes to increafe our knowledge ; but 
it is the greater energy and activity of the power of volition (as 
explained in the former Seflions of this work) that marks man, 
and has given him the empire of the world. 
There is a criterion by which vze may diftinguilh our volun- 
tary ails or thoughts from thofe that are excited by our fcnfa- 
tions ; " The former are always employed about the means to 
acquire pleafurable objects, or to avoid painful ones : while the 
latter are employed about the pofleflion of thofe that are already 
in our power." 
If we turn our eyes upon the fabric of our fellow animals, 
we find they are fupported with bones, covered with (kins, moved 
by mufcles ; that they pofTefs the fame fenfes, acknowledge the 
fame appetites, and are nourifhed by the fame aliment with our- 
felves ; and we fhould hence conclude from the ftrongeft anal- 
ogy, that their internal faculties were alfo in feme meafure fim- 
ilar to our own. 142 
OF INSTINCT. 
Sect. XVI. 17. i. 
Mr. Locke indeed publilhed an opinion, that other animals 
poffefled no abftraft or general ideas, and thought this circum- 
ftance was the barrier between the brute and the human world. 
But thefe abftrafted ideas have been fince demonftrated by Bifh- 
op Berkeley, and allowed by Mr. Hume, to have no exiftence in 
nature, not even in the mind of their inventor, and we are 
hence neceflitated to look for fome other mark of diftinftion. 
The ideas and actions of brutes, like thofe of children, are 
almoft perpetually produced by their prefent pleafures, or their 
prefent pains ; and, except in the few inftances that have been 
mentioned in this Section, they feldom bufy themfelves about 
the means of procuring future blifs, or avoiding future mifery. 
Whilft the acquiring of languages, the making of tools, and 
the labouring for money ; which are all only the means of pro- 
curing pleafure ; and the praying to the Deity, as another meant 
CP procure happinefs^ are charafteriftic of human nature* 
SECT. Sect. XVII. 1.1. 
CATENATION, &c. 
143 
SECT. XVII. 
THE CATENATION OF MOTIONS. 
I. I. Catenations of animal motion. 2. Are produced by irritations, 
by fenfations, by volitions. 3. They continue fame time after they 
have been excited. Caufe of catenation. 4. We can then exert 
our attention on other objeSts. 5. Many catenations of motions go 
on together. 6. Some links of the catenations of motions may be 
left 'without difuniting the chain. 7. Interrupted circles of mo- 
tion continue confufedly till they come to the part of the circle, 
where they were difurbed. 8. Weaker catenations are difever- 
ed by f ranger. 9. Then new catenations take place. 10. Much 
effort prevents their re-uniting. Impediment offpeech. 11. Trains 
more eafily difevered than circles. 12. Sleep def roys volition and 
external fimulus. II. Infances of various catenations in a young 
lady playing on the harpf chord. III. 1. What catenations are 
the frongef. 2. Irritations joined with afociations from frong- 
ef connexions. Vital motions. 3. New links with increafed 
forcey cold fits offever produced. 4. New links with decreafed 
force. Cold bath. $. Irritation joined with fenfation. Inflam- 
matory fever. Why children cannot tickle themfelves. 6. Voli- 
tion joined with fenfation. Irritative ideas of found become fenfi- 
ble. 7. Ideas of imagination difevered by irritations, by volition, 
produblion of furprife. 
I. I. To inveftigate with precifion the catenations of animal 
motions, it would be well to attend to the manner of their pro- 
duction ; but we cannot begin this difquifition early enough for 
this purpofe, as the catenations of motion feem to begin with 
life, and are only extinguifhable with it. We have fpoken of 
the power of irritation, of fenfation, of volition, and of aflbcia- 
tion, as preceding the fibrous motions ; we now ftep forwards, 
and confider, that converfely they are in their turn preceded by 
thofe motions ; and that all the fucceflive trains or circles of our 
actions are compofed of this twofold concatenation. Thofe we 
fhall call trains of action, w'hich continue to proceed without 
any ftated repetitions ; and thofe circles of action, when the 
parts of them return at certain periods, though the trains, of 
which they confift, arc not exactly fimilar. The reading an 
epic poem is a train of actions ; the reading a fong with a cho- 
rus at equal diftances in the meafure conftitutes fo many circles 
of action. 
2. Some catenations of animal motion are produced by reiter- 
ated 144 
CATENATION 
Sect. XVII. r. J. 
ated fucceflive irritations, as when we learn to repeat the alpha- 
bet in its order by frequently reading the letters of it. Thus the 
vermicular motions of the bowels were originally produced by 
the fucceflive irritations of the palling aliment; and the fuccef- 
fion of actions of the auricles and ventricles of the heart was 
originally formed by fucceflive flimulus of the blood, tliefe after- 
wards become part of the diurnal circles of animal aftions, as 
appears by the periodical returns of hunger, and the quickened 
pulfe of weak people in the evening. 
Other catenations of animal motion are gradually acquired 
by fucceflive agreeable fenfations, as in learning a favourite fong 
or dance; others by difagreeable fenfations, as in coughing or 
nictitation ; thefe become aflbeiated by frequent repetition, and 
afterwards compofe parts of greater circles of aCtion like thofe 
above mentioned. 
Other catenations of motions are gradually acquired by fre- 
quent voluntary repetitions; as when we deliberately learn to 
march, read, fence, or any mechanic art, the motions of many 
of our mufcles become gradually linked together in trains, tribes, 
or circles of action. Thus when any one at firft begins to ufe 
the tools in turning wood or metals in a lathe, he wills the mo- 
tions of his hand or fingers, till at length thefe actions become 
fo connected with the effeCt, that he feems only to will the 
point of the chiflel. Thefe are caufed by volition, connected 
by aflbeiarion like thofe above defcribed, and afterwards become 
parts of our diurnal trains or circles of aCtion. 
3. All thefe catenations of animal motions are liable to pro- 
ceed fome time after they are excited, unlcfs they are difturbed 
or impeded by other irritations, fenfations, or volitions ; and 
in many inftances in fpite of our endeavours to flop them; and 
this property of animal motions is probably the caufe of their 
catenation. Thus when a child revolves fome minutes on one 
foot, the fpedraof the ambient objeCls appear to circulate round 
him fome time after he falls upon the ground. Thus the pal- 
pitation of the heart continues fome time after the objeCl of fear, 
which occafioned it, is removed. The blufli of Ihame, which is 
an excefs of fenfation, and the glow of anger, which is an excefs 
of volition, continue fome time, though the affeCted perfon finds, 
that thofe emotions were caufed by miftaken faCts, and endeav- 
ours to extinguiih their appearance. See SeCt. XII. 1. 5. 
4. When a circle of motions becomes connected by frequent 
repetitions as above, we can exert our attention ftrongly on oth- 
er objeCls, and the concatenated circle of motions will neverthe- 
lefs proceed in due order j as whilft you are thinking on this 
fubjcCl Sect. XVII. 1.5. 
OF MOTIONS. 
145 
fubjeft, you ufe variety of mufcles in walking about your parlour, 
or in fitting at your writing-table. 
5. Innumerable catenations of motions may proceed at the 
fame time, without incommoding each other. Of thefe are 
the motions of the heart and arteries; thofe of digeflion and 
glandular fecretion ; of the ideas, or fenfual motions; thofe of 
progreflion, and of fpeaking ; the great annual circle of actions 
fo apparent in birds in their times of breeding and moulting; 
the monthly circles of many female animals ; and the diurnal 
circles of fleeping and waking, of fulnefs and inanition. 
6., Some links of fucceflive trains or of fynchronous tribes of 
action may be left out without disjoining the whole. Such are 
our ufual trains of recollection ; after having travelled through 
an entertaining country, and viewed many delightful lawns, 
rolling rivers, and echoing rocks; in the recolle&ion of our 
journey we leave out the many difiriCts, that we crofled, which 
were marked with no peculiar pleafure. Such alfo are our com- 
plex ideas, they are catenated tribes of ideas, which do not per- 
fectly refemble their correfpondent perceptions, becaufe fome of 
the parts are omitted. 
7. If an interrupted circle of aCtions is not entirely di (revered, 
it will continue to proceed confuledly, till it comes to the part 
of the circle, where it was interrupted. 
The vital motions in a fever from drunkennefs, and in other 
periodical difeafes, are inftances of this circumflance. The ac- 
cidental inebriate does not recover himfelf perfedly till about 
the fame hour on the fucceeding day. The accuflomed drunk- 
ard is difordered, if he has not his ufual potation of ferment- 
ed liquor. So if a confiderable part of a connected tribe of ac- 
tion be difturbed, that whole tribe goes on with confufion, till 
the part of the tribe afFeCled regains its accuflomed catenations. 
So vertigo produces vomiting, and a great fecretion of bile, as 
in fea-ficknefs, all thefe being parts of the tribe of irritative cat- 
enations. 
8. Weaker catenated trains may be diflevered by the fudden 
exertion of the flronger. When a child firfl attempts to walk 
acrofs a room, call to him, and he inflantly falls upon the ground. 
So while I am thinking over the virtues of my friends, if the 
tea-kettle fpurt out fome hot water on my flocking ; the fudden 
pain breaks the weaker chain of ideas, and introduces A new 
group of figures of its own. This circumflance is extended to 
fome unnatural trains of adion, which have not been confirmed 
by long habit; as the hiccough, or an ague-fit, which are fre- 
quently curabl»by furprife. A young lady about eleven years old 
had for five days had a contraction of one mufcle in her- fore arm. 
Vol. I. U and 146 
CATENATION 
Sect. XVII. 1. 9, 
and another in her arm, which occurred four or five times every 
minute ; the mufcles were feen to leap, but without bending the 
arm. To counteract this new morbid habit, iffue was placed 
over the convulfed mufcle of her arm, and an adhefive plafter 
wrapped tight like a bandage over the whole fore arm, by which 
the new motions were immediately deftroyed, but the means 
were continued fome weeks to prevent a return. 
9. If any circle of actions is diffevered, either by omiflion of 
fome of the links, as in deep, or by infertion of other links, as 
in furprife, new catenations take place in a greater or lefs degree. 
The laft link of the broken chain of actions becomes connected 
with the new motion which has broken it, or with that which 
was nearelt the link omitted j and thefe new catenations pro- 
ceed inftead of the old ones. Hence the periodic rctuins of 
ajue-fits, and the chimeras of our dreams. 
10. If a train of actions is diffevered, much effort of volition 
or fenfation will prevent its being reltored. Thus in the com- 
mon impediment of fpeech, when the affociation of the motions 
of the mufcles of enunciation with the idea of the word to be 
fpoken is difordcred, the great voluntary efforts, which dillort 
the countenance, prevent the rejoining of the broken aflbeia- 
tions. See No. II. 10. of this Section. It is thus likewife ob- 
fervable in fome inflammations of the bowels, the too llrong ef- 
forts made by the mufcles to Carry forwards the offending ma- 
terial fixes it more firmly in its place, and prevents the cure. So 
in endeavouring to recal to our memory fome particular word 
of a fentence, if we exert ourfelves too ilrongly about it, we are 
lefs likely to regain it. 
11. Catenated trains or tribes of a£lion are eafier diffevered 
than catenated circles of action. Hence in epileptic fits the 
iynchronous connected tribes of aftion, which keep the body 
ere£l, are diflevered, but the circle of vital motions continues 
undifturbed. 
12. Sleep deftroys the power of volition, and precludes the 
ftimuli of external objects, and thence diflevers the trains, of 
which thefe are a part j which confirms the other catenations, 
as thofe of the vital motions, fecretions, and abforptions; and 
produces the new trains of ideas, which conftitute our dreams. 
II. 1. All the preceding circumftances of the catenations of 
animal motions will be more clearly underftood by the follow- 
ing example of a perfon learning mufic : and when we recollect 
the variety of mechanic arts, which are performed by affociated 
trains of mufcular actions catenated with the effects they pro- 
duce, as in knitting, netting, weaving ; and the greater variety 
of affociated trains of ideas caufed or catenated by volitions or 
fenfations, Sect. XVII. 2. 2. 
OF MOTIONS. 
147 
fenfations, as in our hourly .modes of reafoning, or imagining, 
or recollecting, we (hall gain fome idea of the innumerable cat- 
enated trains and circles of action, which form the tenor of our 
lives, and which began, and will only ceafe entirely with them. 
2. When a young lady begins to learn mufic, fixe voluntarily 
applies herfelf to the characters of hermufic-book, and by many 
repetitions endeavours to catenate them with the proportions of 
found, of which they are fymbcls. The ideas excited by the 
mufical characters are flowly connected with the keys of the 
harpfichord, and much effort is neceffary to produce every note 
with the proper finger, and in its due place and time ; till at 
length a train of voluntary exertions becomes catenated with 
certain irritations. As the various notes by frequent repetitions 
become connected in the order, in which they are produced, a 
new catenation of fenfitive exertions becomes mixed with the 
voluntary ones above defcribed; and not only the mufical fym- 
bols of crotchets and quavers, but the auditory notes and tones 
at the fame time, become fo many fucceflive or fynchronous 
links in this circle of catenated aClions. 
At length the motions of her fingers become catenated with 
the mufical characters; and thefe no fooner ftrike the eye, than 
the finger preffes down the key without any voluntary attention 
between them ; the activity of the hand being connected with 
the irritation of the figure or place of the mufical fymbol on rhe 
retina; till at length by frequent repetitions of the fame tune the 
movements of her fingers in playing, and the mufcles of the 
larynx in finging, become affociated with each other, and form 
part of thofe intricate trains and circles of catenated motions, 
according with the fecond article of the preceding propoutions 
in No. i. of this SeCtion. 
3. Befides the facility, which bv habit attends the execution 
of this mufical performance, a curious circumftance occurs, 
which is, that when our young mufician has begun a tune, (he 
finds herfelf inclined to continue it; and that even when fhe is 
carelefsly finging alone without attending to her own fong; 
according with the third preceding article. 
4. At the fame time that our young performer continues to 
paly with great exaftnefs this accuftomed tune, (he can bend 
her mind, and that intenfely, on fome other objeft, according 
with the fourth article of the preceding propofitions. 
The manufeript copy of this work was lent to many of my 
friends at different times for the purpofe of gaining their opin- 
ions and criticifms on many parts of it, and I found the follow- 
ing anecdote written with a pencil oppofite to this page, but am 
not certain by whom. " I remember feeing the pretty young 
actrefs. 148 
CATENATION 
Sect. XVII. 2. 5. 
aclrefs, who fucceeded Mrs. Arne in the performance of the 
celebrated Padlock, rehearfe the mufical parts at her harpfichord 
under the eye of her mafier with great tafte and accuracy ; 
though I obferved her countenance full of emotion, which I 
could not account for; at laft (he fuddenly burft into tears ; for 
fhe had ail this time be6n eyeing a beloved canary bird, fuffer- 
ing great agonies, which at that inftant fell dead from its perch.'* 
5. At the lame time many other catenated circles of action 
are going on in the perfon of our fair mufician, as well as the 
motions of her fingers, fuch as the vital motions, refpiration, the. 
movements of her eyes and eyelids, and of the intricate mufcles 
of vocality, according with the fifth preceding article. 
6. If by any ftrong impreflion on the mind of our fair mufi- 
cian flic fliould be interrupted for a very inconfiderable time, fhe 
can ftill continue her performance, according to the fixth article. 
7. If however this interruption be greater, though the chain 
of actions be not diflevered, it proceeds confufedly, and our 
young performer continues indeed to play, but in a hurry with- 
out accuracy and elegance, till fhe begins the tune again, accord- 
ing to the fevcnth of the preceding articles. 
8. But if this interruption be ftill greater, the circle of ac- 
tions becomes entirely diflevered, and fhe finds herfclf immedi- 
ately under the necefiity to begin over again to recover the loft 
catenation, according to the eighth preceding article. 
9. Or in trying to recover it file will fing fome diflbnant notes, 
or ft rike fome improper keys, according bo the ninth preceding 
article. 
10. A very remarkable thing attends this breach of catena- 
tion, if the performer has forgotten fome word of her fong, the 
more energy of mind fhe ufes about it, the more diftant is fhe 
from regaining it; and artfully employs her mind in part on 
fome other object, or endeavours to dull its perceptions, contin- 
uing to repeat as it were inconfcioufly, the former part of the 
long, that fhe remembers, in hopes to regain the loft connexion. 
For if the aflivjty of the mind itfelf be more energetic, or 
takes its attention more, than the connecting word, which is 
wanted ; it will not perceive the {lighter link of this loft word 5 
as who liftens to a feeble found, muft be very filent and mo- 
tionlefs j fc that in this cafe the very vigour of the mind itfelf 
teems to prevent it from regaining the loft catenation, as well as 
the too great exertion in endeavouring to regain it, according to 
the tenth preceding article. 
We frequently experience, when we are doubtful about the 
fpelling of a word, that the greater voluntary exertion we ufe, 
that is the more intenfely we think about it, the further are we 
from Sect. XVII. 2. it. 
OF MOTIONS. 
149 
from regaining the loft aflbciation between the letters of it, but 
which readily recurs when we have become carelefs about it. In 
the fame manner, after having for an hour laboured to recoiled 
the name of feme abfent perfon, it fhall feem, particularly after 
ilcep, to come into the mind as it were fpontaneoufly ; that is, 
the word we are in fearch of, was joined to the preceding one 
by aflbciation ; this aflbciation being diflevered, we endeavour 
to recover it by volition ; this very ailion of the mind ftrikes 
our attention more, than the faint link of aflbciation, and we 
find it impoflible by this means to retrieve the loft wbrd. After 
fleep, when volition is entirely fufpended, the mind becomes 
capable of perching the fainter link of aflbciation, and the word 
is regained. 
On this circumftance depends the impediment of fpeech be- 
fore mentioned ; the fir ft fyllable of a word is caufoble by vo- 
lition, but the remainder of it is in common converfation intro- 
duced by its aflbeiations with this firft fyllable acquired by long 
habit. Hence when the mind of the ftammerer is vehemently 
employed on fome idea of ambition of fhining, or fear of not 
fucceeding, the aflbeiations of the motions of the mufcles of ar- 
ticulation with each other become diflevered by this greater ex- 
ertion, and he endeavours in vain by voluntary efforts to rejoin 
the broken aflbciation. For this purpofe he continues to re- 
peat the firft fyllable, which is caufable by volition, and ftrives 
in vain, by various diftortions of countenance, to produce the 
next links, which are fubject to aflbciation. See Clafs IV. 3. 1. 1. 
11. After our accomplished mufician has acquired great va- 
riety of tunes and fongs, fo that fome of them begin to ceafe to 
be eafily recolledled, fhe finds progreflive trains of mufical 
notes more frequently forgotten, than thofe which are compo- 
fed of reiterated circles, according with the eleventh preceding 
article. 
12. To finifh our example w;ith the preceding articles we 
muft at length fuppofe, that our fair performer falls afleep over 
her harpfichord ; and thus by fufpenfion of volition, and the ex- 
clufion of external ftimuli, fhe diflevers the trains and circles of 
her mufical exertions. 
III. 1. Many of thefe circumftances of catenations of mo- 
tions receive an cafy explanation from the four following confe- 
quences to the feventh law of animal caufation in Se<ft. IV. 
Thefe are, firft, that thofe fucceflions or combinations of anima! 
motions^ whether they were united by caufation, aflbciation, or 
catenation, which have been moft frequently repeated, acquire 
the ftrongeft connexion. Secondly, that of thefe, thofe, which 
have been lefs frequently mixed with other trains or tribes of 
motion, 150 
CATENATION 
Sect. XVII. 3. 2. 
motion, have the ftrongeft connexion. Thirdly, that of thefe, 
thofe, which were firft formed, have the ftrongeft connexion. 
Fourthly, that if an animal motion be excited by more than one 
eaufation, aflbciation, or catenation, at the fame time, it will be 
performed with greater energy. 
2. Hence alfo we underftand, why the catenations of irrita- 
tive motions are more ftrongly connected than thofe of the oth- 
er clafles, where the quantity of unmixed repetition has been 
equal ; becaufe they were firft formed. Such are thofe of the 
fecerning and abforbent fyftems of veflels, where the adtion of 
the gland produces a fluid, which ftimulates the mouths of its 
correfpondent abforbents. The afibciated motions feem to be 
the next moft ftrongly united, from their frequent repetition ; 
and where both thefe circumftances unite, as in the vital motions, 
their catenations are indiflaluble but by the deftrudfion of the 
animal. 
3. Where a new link has been introduced into a circle of 
actions by fome accidental defeat of ftimulus ; if that defedt of 
ftimulus be repeated at the fame part of the circle a fccond or 
a third time, the defective motions thus produced, both by the 
repeated defeat of ftimulus and by their catenation with the 
parts of the circle of actions, will be performed with lefs and 
ids energy. Thus if any perfon is expofed to cold at a certain 
hour to-day, fo long as to render fome part of the fyftem for 
a time torpid ; and is again expofed to it at the fame hour to- 
morrow, and the next day ; he will be more and more affected 
by it, till at length a cold fit of fever is completely formed, as 
happens at the beginning of many of thofe fevers, which are 
called nervous or low fevers. Where the patient has flight pe- 
riodical Ihiverings and palenefs for many days before the febrile 
paroxyfin is completely formed. 
4. On the contrary if the expofure to cold be for fo fhort a 
time, as not to induce any confiderable degree of torpor or qui- 
cfcence, and is repeated daily as above mentioned, it lofes its 
eifefi more and more at every repetition, till the conftitution 
can bear it without inconvenience, or indeed without being con- 
feious of it. As in walking into the cold air in frofty weather. 
The fame rule is applicable to increafed ftimulus, as of heat, or 
vinous fpirit, within certain limits, as is applied in the two laft 
paragraphs to Deficient Stimulus, as is further explained in Se£t. 
XXXVI. on the Periods of Difeafes. 
5. Where irritation coincides with fenfation to produce the 
fame catenations of motion, as in inflammatory fevers, they are 
excited with ftill greater energy than by the irritation alone. 
So when children expect to be tickled in play, by a feather light- 
ly Sect. XVII. 3. 6. 
OF MOTIONS. 
151 
ly paffed over the lips, or by gently vellicating the foies of their 
feet, laughter is moft vehemently excited ; though they can 
flimulate thefe parts with their own fingers unmoved. Here 
the pleafurable idea of playfulnefs coincides with the vellication ; 
and there is no voluntary exertion ufed to diminifh the fenfa- 
tion, as there would be, if a child ihould endeavour to tickle 
himfelf. See Se£t. XXXIV. i. 4. 
6. And laftly the motions excited by the junction of volun- 
tary exertion with irritation are performed with more energy, 
than thofe by irritation fingly ; as when we liften to final! 
noifes, as to the ticking of a watch in the night, we perceive 
the moft weak founds, that are at other times unheeded. So 
when we attend to the irritative ideas of found in our ears, 
which are generally not attended to, we can hear them ; and 
can fee the fpe&ra of objects, which remain in the eye, when- 
ever we pleafe to exert our voluntary power in aid of thofe weak 
actions of the retina, or of the auditory nerve. 
7. The temporary catenations of ideas, which are caufed by 
the fenfations of pleafure or pain, are eafily diflevered either by 
irritations, as when a fudden noife difturbs a day-dream ; or by 
the power of volition, as when we awake from deep. Hence in 
our waking hours, whenever an idea occurs, which is incongru- 
ous to our former experience, we inltantly diflever the train of 
imagination by the power of volition, and compare the incon- 
gruous idea with our previous knowledge of nature, and rejedb 
it. This operation of the mind has not yet acquired a fpecific 
name, though it is exerted every minute of our waking hours; 
unlefs it may be termed intuitive analogy. It is an act of 
reafoning of which we are unconfcious except from its effects 
in preferving the congruity of our ideas, aud bears the fame re- 
lation to the fenforial power of volition, that irritative ideas, of 
which we are inconfcious except by their effects, do to the fenfo- 
rial power of irritation j as the former is produced by volition 
without our attention to it, and the latter by irritation without 
our attention to them. 
If on the other hand a train of imagination or of voluntary 
ideas are excited with great energy, and paffmg on with great 
vivacity, and become diflevered by fome violent ftimulus, as the 
difcharge of a piftol near one's ear, another circumftance takes 
place, which is termed surprise ; which by exciting violent 
irritation, and violent fenfation, employs for a time the whole 
fenforial energy, and thus diflevers the palling trains of ideas, 
before the power of volition has time to compare them with the 
ufual phenomena of nature. In this cafe fear is generally the 
companion of furprife, and adds to our embarraftinent, as every 152 
CzlTENATION, &c. 
Sect. XVII. 3. 7, 
one experiences in fame degree when he hears a noife in the 
dark, which he cannot inftantly account for. This catenation 
of fear with furprife is owing to our perpetual experience of in- 
juries from external bodies in motion, unlefs we are upon our 
guard againft them. See Se<£l. XVIII. 17. XIX. 2. 
Many other examples of the catenations of animal motions 
are explained in Seft. XXXVI. on the Periods of Difeafes. 
i > - J ft Sect. XVIII. 1. 
OF SLEEP. 
153 
SECT. 
XVIIL 
OE SLEEP. 
I. Volition is fufpended in fleep. 2. Senfalion continues. Dreams 
prevent delirium and inflammation. 3. Nightmare. 4. Ceafe- 
lefs flow of ideas in dreams. 5. We feem to receive them by the 
fenfes. Optic nerve perfectly fenfi'ble in fleep. Eyes lefs dazzled 
after dreaming of vfible objects. 6. Reverie, belief, 7. How 
we diflinguifh ideas from perceptions. 8. Variety of feenerp in 
dreams, excellence of the fenfe of viflon. 9. Novelty of combina- 
tion in dreams. 10. Diflinclnefs of imagery in dreams. 11. Ra- 
pidity of tranfaflion in dreams. 12. Of meafuring time. Oj 
dramatic time and place. Why a dull play induces fleep, and an 
inter efling one reverie. 13. Confcioufnefs of cur ex fence and 
identity in dreams. 14. How we awake fometimes fuddenly, 
fometimes frequently. 13. Irritative motions continue in fleep, 
internal irritations are fucceeded by fenfation. SenfibUity increafes' 
during fleep, and irritability. Morning dreams. Why epilepfies 
occur in fleep. Ecflafy of children. Cafe of convulflons in fleep. 
Cramp, why painful. Aflhma. Morning fwe ats. Increafe of 
heat. Increafe of urine in fleep. Why more liable to take cold in 
fleep. Catarrh from thin night-caps. Why we feel chilly at the 
approach of fleep, and at waking in the open air. 16. Why the 
gout commences infleep. Secretions are more copious infleep, young 
animals and plants grow more in fleep. 17. Inconfflency of 
dr cams. Abfence of furprife In dreams. 18. Why we forget 
fame dreams and not others. 19. Sleep talkers awake with fur- 
prife. 20. Remote caufes offleep. Atmofphere with lefs oxygene. 
Compreflion of the brain in the fpina bifida. By whirling on a 
horizontal wheel. By cold. 21. Definition of fleep. 
i. There are four fituations of our fyftem, which in their 
moderate degrees are not ufually termed difeafes, and yet 
abound with many very curious and inftrudive phenomena; 
thefe are ileep, reverie, vertigo, drunkennefs. Thefe we (hall 
previoufly consider, before we ftep forwards to develop the caufes 
and cures of difeafes with the modes of the operation of medi- 
cines. 
As all thofe trains and tribes of animal motion, which are 
fubjeded to volition, were the laft that were caufed, their con- 
nexion is weaker than that of the other clafles ; and there is 
a peculiar circumftance attending this caufation, which is, that 
it is entirely fufpended during deep; whilft the Qthpr daffes of 
Vol. I. W * motion, 154 
OF SLEEP. 
Sect. XVIII. i, 
motion, which are more immediately neceflary to life, as thofe 
caufed by internal ftimuli, for inltance the pulfations of the 
heart and arteries, or thofe catenated, with pleafurable fenfa- 
tion, as the powers of digeftion, continue to ftrengthen their 
habits without interruption. Thus though man in his deeping 
Hate is a much lefs perfect animal, than in his Waking hours; 
and though he confumes more than one third of his life in this 
his irrational fituation ; yet is the wifdom of the Author of na- 
ture manifelt even in this feeming imperfection of his work. 
The truth of this alfertion with refpeCl to the large mufcles 
of the body, which are concerned in locomotion, is evident; 
as no one in perfect fanity walks about in his deep, or performs 
any domeftic offices : and in refpeCt to the mind, we never ex- 
ercife our reafon or recollection in dreams ; we may fometimes 
feem diffracted between contending paflions, but we never 
compare their objects, or deliberate about the acquifition of thofe 
objeCts, if our deep is perfect. And though many fynchronous 
tribes or fucceffive trains of ideas may reprefent the houfes or 
walks, which have real exiftence, yet are they here introduced 
by their connexion with our fenfations, and are in truth ideas 
of imagination, not of recollection. 
2. For our fenfations of pleafure and pain are experienced, 
with great vivacity in our dreams; and hence all that motley 
group of ideas, which are caufed by them, called the ideas of 
imagination, with their various adbciated trains, are in a very 
vivid manner aCted over in the fenforium ; and thefe fometimes 
call into action the larger mufcles, which have been much affo- 
ciated with them ; as appears from the muttering fentences, 
which fome people utter in their dreams, and from the obfcure 
barking of deeping dogs, and the motions of their feet and noftrils. 
This perpetual Row of the trains of ideas, which conftitute our 
dreams, and which are caufed by painful or pleafurable fenia- 
tion, might at firft view be conceived to be an ufelefs expen- 
diture of fenforial power. But it has been fhewn, that thofe 
motions, which are perpetually excited, as thofe of the arterial 
fyffem by the ftimulus of the blood, are attended by a great ac- 
cumulation of fenforial power, after they have been for a time 
fufpended ; as the hot-fit of fever is the confequence of the 
cold one. Now as thefe trains of ideas caufed by fenfation are 
perpetually excited during our waking hours, if they were to be 
fufpended in deep like the voluntary motions, (which are exerted 
only by intervals during our waking hours,) an accumulation 
of fenforial power would follow •, and on our awaking a delirium 
would fupervene, fince thefe ideas caufed by fenfation would 
be produced with fuch energy, that we Ihould miltake the trains 
of Sect. XVIII. 3. 
OF SLEEP. 
155 
of imagination for ideas excited by irritation ; as perpetually 
happens to people debilitated by fevers on their firft awaking : 
for in thefe fevers with debility the general quantity of irrita- 
tion being diminifhed, that of fenfation is increafed. In like 
manner if the actions of the ftomach, inteftines, and various 
glands, which are perhaps in part at leaft caufed by or catenated 
with agreeable fenfarion, and which perpetually exilt during 
our waking hours, were like the voluntary motions fufpended in 
our fleep ; the great accumulation of fenforial power, which 
would necefl'arily follow, would be liable to excite inflammation 
in them. 
3. When by our continued pofture in fleep tome uneafy 
fenfations are produced, we either gradually awake by the exer- 
tion of volition, or the mufcles connected by habit with fuch 
tenfations alter the pofition of the body ; but where the fleep is 
uncommonly profound, and thofe uneafy tenfations great, the 
difeafe called the incubus, or nightmare, is produced. Here the 
defire of moving the body is painfully exerted, but the power of 
moving it, or volition, is incapable of action, till we awake. 
Many lefs difagreeable ftruggles in our dreams, as when we wifh 
in vain to fly from terrifying objects, confiitute a flighter degree 
of this difeafe. In awaking from the nightmare I have more 
than once obferved, that there was no diforder in my pulte ; 
nor do I believe the refpiration is laborious, as tome have affirm- 
ed. It occurs to people whofe fleep is too profound, and tome 
difagreeable fenfation exifts, which at other times would have 
awakened them, and have thence prevented the difeafe of night- 
mare ; as after great fatigue or hunger with too large afupper and 
wine, which occafion our ileep to be uncommonly profound. 
See No. 14, of this Section. 
4. As the larger mufcles of the body are much more fre- 
quently excited by volition than by fenfation, they are but tel- 
dom brought into action in our fleep : but the ideas of the mind 
are by habit much more frequently connected with fenfation 
than with volition ; and hence the ceafelefs flow of our ideas in 
dreams. Every one's experience will teach him this truth, for 
we all daily exert much voluntary mufcular motion : but few 
of mankind can bear the fatigue of much voluntary thinking. 
5. A very curious circumltance attending thefe our fleeping 
imaginations is, that we teem to receive them by the fenfes. 
The mufcles, which are fubtervient to the external organs of 
tente, are connected with volition, and ceafe to art in fleep ; 
hence the eyelids areclofed,andthe tympanum of the car relaxed ; 
and it is probable a fimilarity of voluntary exertion may be necef- 
fary for the perceptions of the other nerves of fenfe ; for it is 
obferved 156 
OF SLEEP. 
Sect. XVIII. 5. 
cbferved that the papillae of the tongue can be feen to become 
erected, when we attempt to tafte any thing extremely grateful. 
Hewfon Exper. Enquir. V. ii. 186. Albini Annot. Acad. L. i. 
c. 15. Add to this, that the immediate organs of fenfe have no 
objects to excite them in the darknefs and iilence of the night; 
but their nerves of fenfe neverthelefs continue to poflefs their 
perfect activity fubfervient to all their numerous fenfitive con- 
nexions. This vivacity of our nerves of fenfe during the time 
of fleep is evinced by a circumltance, whidh almofl every one 
mult at feme time or other have experienced ; that is, if we 
fleep in the daylight, and endeavour to fee fome object in our 
dream, the light is exceedingly painful to our eyes ; and after 
repeated ftruggles we lament in our Deep, that we cannot fee it. 
In this cafe I apprehend the eyelid is in fome degree opened by 
the vehemence of our fenfations ; and, the iris being dilated, 
the optic nerve (hews as great or greater fenfibility than in our 
waking hours. See No. 15. of this Section. 
When we are forcibly waked at midnight from profound 
fleep, our eyes are much dazzled with the light of the candle for 
a mipute or two, after there has been fuflicient time allowed for 
the contraction of the iris ; which is owing to the accumulation 
of fenforial power in the organ of vifion during its Rate of lefs 
activity. But when we have dreamt much of vifible objects, 
this accumulation of fenforial power in the organ of vifion is 
leflened or prevented, and we awake in the morning without be- 
ing dazzled with the light, after the iris has had time to con- 
tract itfelf. This is a matter of great curiofity, and may be thus 
tried by any one in the day-light. Clofe your eyes, and cover 
them with your hat ; think for a minute on a tune, which you 
are accuftomed to, and endeavour to fing it with as little activity 
of mind as polfible. Suddenly uncover and open your eyes, 
and in one fecond of time the iris will contraCt itfelf, but you 
will perceive the day more luminous for feveral feconds, owing 
to the accumulation of fenforial power in the optic nerve. 
Then again clofe and cover your eyes, and think intenfely on 
a cube of ivory two inches diameter, attending fir ft to the north 
and fouth fides of it, and then to the other four fides of it; then 
get a clear image in your mind's eye of all the fides of the fame 
cube coloured red ; and then of it coloured green ; and then of 
it coloured blue 5 laftly, open your eyes as in the former exper- 
iment, and after the fir ft fecond of time allowed for the con- 
traction of the iris, you will not perceive any increafe of the 
light of the day, or dazzling; becaufe now there is no accumu- 
lation of fenforial power in the optic nerve ; that having been 
expended by its action in thinking over vifible objeCts. 
This Sect. XVIII. 6. 
OF SLEEP. 
157 
This experiment is not eafy to be made at firft, but by a few 
patient trials the fa£t appears very certain ; and (hews clearly, 
that our ideas of imagination are repetitions of the motions of 
the nerve, which were originally occafioned by the ftimulus of 
external bodies ; becaufe they equally expend the fenfcrial power 
in the organ of fenfe. See Se6t. III. 4. which is analogous 10 
our being as much fatigued by thinking as by labour. 
6. Nor is it in our dreams alone, but even in our waking rev- 
eries, and in great efforts of invention, fo great is the vivacity of our 
ideas, that we do not for a time diftinguifh them from the real 
prefence of fubftantial objects: though the external organs of 
fenfe are open, and furrounded with their ufual ftimuli. Thus 
whilft I am thinking over the beautiful valley, through which I 
yefterday travelled, I do not perceive the furniture of my room : 
and there are fome, whofe waking imaginations are lb apt to run 
into perfect reverie, that in their common attention to a favour- 
ite idea they do not hear the voice of the companion, who ac- 
cofts them, unlefs it is repeated with unufual energy. 
This perpetual miftake in dreams and reveries, where our 
ideas of imagination are attended with a belief of the prefence 
of external objects, evinces beyond a doubt, that all our ideas 
are repetitions of the motions of the nerves of fenfe, by which 
they were acquired ; and that this belief is not, as fome late phi- 
lofophers contend, an inftinct neceiTarily connected only with 
our perceptions. 
7. A curious queftion demands our attention in this place ; 
as we do not diftinguilh in our dreams and reveries between our 
perceptions of external objects, and our ideas of them in their 
abfence, how do we diftmguifh them at any time ? In a dream, 
if the fweetnefs of fugar occurs to my imagination, the white- 
nefs and hardnefs of it, which were ideas ufually connected with 
the fweetnefs, immediately follow in the train ; and I believe a 
material lump of fugar prefent before my fenfes ; but in my 
waking hours, if the fweetnefs occurs to my imagination, the 
ftimulus of the table to my hand, or of the window to my eye, 
prevents the other ideas of the hardnefs and whitenefs of the fu- 
gar from fucceeding ; and hence I perceive the fallacy, and dif- 
believe the exiftence of objects correfpondent to thofe ideas, 
whole tribes or trains are broken by the ftimulus of other ob- 
jects. And further in our waking hours, we frequently exert 
our volition in comparing prefent appearances with fuch, as we 
have ufually obferved ; and thus correct the errors of one fenfe 
by our general knowledge of nature by intuitive analogy. See 
Seft. XVII. 3. 7. Whereas in dreams the power of volition is 
fufpended, we can recollect and compare our prefent ideas with 
none 158 
OF SLEEP. 
Sect. XVIII. 8. 
none of our acquired knowledge, and are hence incapable of ob- 
ierving any abfurdities in them. 
By this criterion we diflinguifh our waking from our deeping 
hours, we can voluntarily recollect our deeping ideas, wien we 
are awake, and compare them with our waking ones ■, but we 
cannot in our deep voluntarily recollect our waking ideas at all. 
8. The vaft variety of feenery, novelty of combination, and 
diftinftnefs of imagery, are other curious circumftances of our 
deeping imaginations. The variety of feenery feems to arife 
from the fuperior activity and excellence of our fenfe of vifion ; 
which in an inftant unfolds to the mind extenfive fields of pleaf- 
urable ideas ; while the other fenfes collect their objects dowly, 
and with little combination ; add to this, that the ideas, which 
this organ prefents us with, are more frequently connected with- 
our fenfation than thofe of any other. 
9. The great novelty of combination is owing to another cir- 
cumftancethe trains of ideas, which are carried on in our 
waking thoughts, are in our dreams didevered in a thoufand 
places by the fufpenlion of volition, and the abfence of irritative 
ideas, and are hence perpetually falling into new catenations. 
As explained in Sedt. XVI. 1. 9. For the power of volition is 
perpetually exerted during our waking hours in comparing our 
pafiing trains of ideas with our acquired knowledge of nature, 
and thus forms many intermediate links in their catenation. 
And the irritative ideas excited by the ftimulus of the obje&s, 
with which we are furrounded, are every moment intruded up- 
on us, and form other links of our unceafing catenations of ideas. 
10. The abfence of the ftimuliof external bodies, and of vo- 
lition, in our dreams renders the organs of fenfe liable to be 
more ftrongly affedted by the powers of fenfation, and of aflb- 
ciation. For our delircs or averfions, or the obtrufions of fur- 
rounding bodies, diflever the fenfitive and aflbeiate tribes of 
ideas in our waking hours by introducing thofe of irritation and 
volition amongft them. Hence proceeds the fuperior diftimT- 
iiefs of pleafurable or painful imagery in our fieep ; for we recal 
the figure and the features of a long loft friend, whom we loved, 
in our dreams with much more accuracy and vivacity than in 
our waking thoughts. This circumftance contributes to prove, 
that our ideas of imagination are reiterations of thofe motions 
of our organs of fenfe, which were excited by external objects; 
becaufe while we are expofed to the ftimuli of prefent objects, 
cur ideas of abfent objects cannot be fo diftinclly formed. 
11. 'fhe rapidity of the fucceflion of tranfa£lions in our 
dreams is almoft inconceivable; infomuch that, when we are 
accidentally awakened by the jarring of a door, which is opened 
into Sect. XVIII. 12. 
OF SLEEP. 
159 
into our bedchamber, we fometimes ftream a whole hiftory of 
thieves or fire in the very inftant of awaking. 
During the fufpenfion of volition we cannot compare our 
other ideas with thofe of the parts of time in which they exift ; 
that is, we cannot compare the imaginary fcene, which is before 
us, with thofe changes of it, which precede or follow it: becaufe 
this act of comparing requires recollection or voluntary exertion. 
Whereas in our waking hours, we are perpetually making this 
comparifon, and by that means our waking ideas are kept con- 
fiftent with each other by intuitive analogy; but this compari- 
fon retards the fucceflion of them, by occafioning their repeti- 
tion. ' Add to this, that the tranfadfions of our dreams confitt 
chiefly of vifible ideas, and that a whole hiftory of thieves and fire 
may be beheld in an inftant of rime like the figures in a picture. 
12. From this incapacity of attending to the parts of time in 
our dreams, arifes our ignorance of the length of the night ; 
which, but from our conftant experience to the contrary, we 
fhould conclude was but a few minutes, when our fleep is per- 
fect. The fame happens in our reveries; thus when we are 
poflefled with vehement joy, grief, or anger, time appears Ihort, 
for we exert no volition to compare the prefent feenery with die 
pall or future ; but when we are compelled to perform thofe ex- 
ercifes of mind or body, which are unmixed with paflion, as in 
travelling over a dreary country, time appears long ; for our de- 
fire to finilh dur journey occafions us more frequently to com- 
pare our prefent fituation with the parts of time or place, which 
are before and behind us. 
So when we are enveloped in deep contemplation of any kind, 
or in reverie, as in reading a very interefting play or romance, 
we meafure time very inaccurately ; and hence, if a play greatly 
aft'cCts our paflions, the abfurdities of palling over many days or 
years, and of perpetual changes of place, are not perceived by 
the audience ; as is experienced by every one, who reads or fees 
fome plays of the immortal Shakipeare ; but it is necefiary for 
inferior authors to obferve thofe rules of the and ^-n>a 
inculcated by Aiiftotle, bccaufe their works do not intereft the 
pallions fufliciently to produce complete reverie. 
Thofe works, however, whether a romance or a fermon, which 
do not intereft us fo much as to induce reverie, may neverthe- 
lefs incline us to fleep. For thofe pleafurable ideas, which are 
prefented to us, and are too gentle to excite laughter, (which is 
attended with interrupted voluntary exertions, as explained 
SeCt. XXXIV. 1.4.) and which are not accompanied with any 
other emotion, which ufually excites fome voluntary exertion, 
as anger, or fear, are liable to produce fleep) which confifis in 160 
OF SLEEP. 
Sect. XVIII. 13. 
a fufpenflon of all voluntary power. But if the ideas thus pre- 
fented to us, intereft our attention, and are accompanied with fo 
much pleafurable or painful fenfation as to excite our voluntary 
exertion at the fame time, reverie is the confequence. Hence 
an interefting play produces reverie, a tedious one produces fleep 1 
in the latter we become exhaufted by attention, and are not ex- 
cited to any voluntary exertion, and therefore deep ? in the 
former we are excited by feme emotion, which prevents by its 
pain the fufpenfion of volition, and in as much as it interefts us, 
induces reverie, as explained in the next Section. 
But when our deep is imperfect, as when we have determin- 
ed to rife in half an hour, time appears longer to us than in 
molt bther fituations. Here our folicitude not to overdeep the 
determined time induces us in this imperfect deep to compare 
the quick changes of imagined feenery with the parts of time or 
place, they would have taken up, had they real exiilence; and 
that more frequently than in our waking hours ; and hence the 
time appears longer to us: and I make no doubt, but the per- 
mitted time appears long to a man going to the gallows, as the 
fear of its quick lapfe will make him think frequently about it. 
13. As we gain our knowledge of time by comparing the 
prelent feenery with the pail and future, and of place by com- 
paring the fituations of objects with each other; fo we gain our 
idea of confcioufnefs by comparing ourfelves with the feenery 
around us ; and of identity by comparing our prefent confciouf- 
nefs with our paft confcioufnefs : as we never think of time or 
place, but when we make the companions above mentioned, fo 
we never think of confcioufnefs, but when we compare our own 
exiftence with that of other objects; nor of identity, but when 
we compare our prefent and our pall confcioufnefs. Hence the 
confcioufnefs of our own exiftence, and of our identity, is owing 
to a voluntary exertion of our minds: and on that account in 
our complete dreams we neither meafure time, are furprifed at 
the fudden changes of place, nor attend to our own exiftence, or 
identity ; becaufe our power of volition is fufpended. But all 
thefe circumftances are more or lefs obfervable in our incom- 
plete ones ; for then we attend a little to the lapfe of time, and 
the changes of place, and to our own exiftence ; and even to 
our identity of perfon ; for a lady feldom dreams, that fhe is a 
foldier; nor a man, that he is brought to bed. 
14. As long as our fenfations only excite their fenfual mo- 
tions, or ideas, our fleep continues found; but as foon as they 
excite deftres or averfions, our fleep becomes imperfect; and 
when that defire or averfion is fo ftrong, as to produce voluntary 
motions, we begin to awake ; the larger mufclcs of the body are 
brought Sect. XVIII. ry. 
OF SLEEP. 
161 
brought into aftion to remove that irritation or fenfation, which 
a continued pofture has caufed; we ftretch our limb;, and 
yawn, and our fleep is thus broken by the accumulation of vol- 
untary power. 
Sometimes it happens, that the aft of waking is fuddenly pro- 
duced, and this foon after the commencement of fleep; which 
is occafioned by fome fenfation fo difagreeable, as inftantane- 
oufly to excite the power of volition j and a temporary action of 
all the voluntary motions fuddenly fucceeds, and we ftart awake* 
This is fometimes accompanied with loud noife in the ears, and 
with fome degree of fear ; and when it is in great excefs, fo as 
to produce continued convulfive motions of thofe mufcles, 
which are generally fubfervient to volition, it becomes epilepfy t 
the fits of which in fome patients generally commence during 
fleep. This differs from the nightmare defcribed in No. 3. of 
this Section, becaufe in that the difagreeable fenfation is not fo 
great as to excite the power of volition into aftion $ for as foon 
as that happens, the difeafe ceafes. 
Another circumftance, which fometimes awakes people foon 
after the commencement of their fleep, is where the voluntary 
power is already fo great in quantity as almoft to prevent them 
from falling afleep, and then a little accumulation of it foon 
again awakens them ; this happens in cafes of infanity, or 
where the njind has been lately much agitated by fear or anger* 
There is another circumftance in which fleep is likewife of 
(hott duration, which arifes from great debility, as after great 
over-fatigue, and in fome fevers, where the ftrengch of the 
patient is greatly diminilhed: as in thefe cafes the pulfe inter- 
mits or flutters, and the refpiration is previoufly affefted, it 
feems to originate from the want of fome voluntary efforts to 
facilitate refpiration, as when we are awake, and is further 
treated of in Vol. II. Clafs I. 2. 1. 2. on the Difeafcs of the 
Voluntary Power. Art. Somnus interruptus. 
15. We come now to thofe motions which depend on irrita* 
tion. The motions of the arterial and glandular fyftems con- 
tinue in our fleep, proceeding flower indeed, but ftronger and 
more uniformly, than in our waking hours, when they are in- 
commoded by external ftimuli, or by the movements of volition j 
the motions of the mufcles fubfervient to refpiration continue 
to be ftimulatcd into aftion, and the other internal fenfes of hun- 
ger, thirft, and lull, are not only occafionally excited in our fleep, 
but their irritative motions' are fucceeded by their ufual fenfa- 
tions, and make a part of thd farrago of our dreams. Thefe 
fenfations of the want of air, of hunger, thirft, and ly/i, in our 
dreams, contribute to prove, that the nerves ®f the external 
Vol. I. X fenfss 162 
OF SLEEP. 
Sier. XVIII. ly. 
fenfes are alfo alive and excitable in our fleep ; but as the ftimuli 
of external objects are either excluded from them by the dark- 
nefs and filence of the night, or their accefs to them is prevented 
by the fufpenfion of volition, thefe nerves of fenfe fall more 
readily into their connexions with fenfation and with aflbeiation ; 
becaufe much fenforial power, which during the day was ex- 
pended in moving the external organs of fenfe in confequence 
of irritation from external ftimuli, or in confequence of volition, 
becomes now in fome degree accumulated, and renders the in- 
ternal or immediate organs of fenfe more eafily excitable by the 
other fenforial powers. Thus in refpedt to the eye, the irritation 
from external ftimuli, and the power of volition during our 
waking hours, elevate the eyelids, adapt the aperture of the iris 
to the quantify of light, the focus of the cryftalline humour, and 
the angle of the optic axifes to the diftance of the object, all 
which perpetual activity during the day expends much fenforial 
power, which is faved during our fleep. 
Hence it appears, that not only thofe parts of the fyftem, 
which are always excited by internal ftimuli, as the ftomach, 
inteftinal canal, bile-dudls, and the various glands, but the or- 
gans of fenfe alfo may be more violently excited into action by 
the irritation from internal ftimuli, or by fenfation, during our 
fleep than in our waking hours; becaufe during the fufpenfion 
of volition, there is a greater quantity of the fpirit of animation 
to be expended by the other fenforial powers. On this account 
our irritability to internal ftimuli, and our fenfibility to pain or 
plealure, is not only greater in fleep, but increafes as our fleep 
is prolonged. Whence digeftion and fecretion arc performed 
better in fleep, than in our waking hours, and our dreams in the 
morning have greater variety and vivacity, as our fenfibility in- 
creafes, than at night when we firft lie down. And hence epi- 
leptic fits, which are always occafioned by fome difagreeable fen- 
fation, fo frequently attack thofe, who are fubjeft to them, in 
their fleep ; becaufe at this time the fyftem is more excitable by 
painful fenfatian in confequence of internal ftimuli; and the 
power of volition is then fuddenly exerted to relieve this pain, 
as explained Sedl. XXXIV. i. 4. 
There is a difeafe, which frequently atTe&s children in the 
cradle, which is termed eeftafy, and feems to confift in certain 
exertions to relieve painful fenfation, in which the voluntary 
power is not fo far excited as totally to awaken them, and yet is 
fufficient to remove the difagreeable fenfation, which excites 
it; in this cafe changing the pofture of the child frequently 
relieves it. 
I hava at this time under my care an elegant young man 
about Sect. XVIII. 15. 
OF SLEEP. 
163 
about twenty-two years of age, who feldom fleeps more than an 
hour without experiencing a convulfion fit; which ceafes in 
about half a minute without any fubfequent Itupor. Large 
dofes of opium only prevented the paroxyfms, fo long as they 
prevented him from fleeping by the intoxication, which they in- 
duced. Other medicineshad no effect on him. He was gently 
awakened every half hour for one night, but without good ef- 
fect, as he foon flept again, and the fit returned at about the 
fame periods of time, for the accumulated fenforial power, which 
occafioned the increafed fenfibility to pain, was not thus exhauft- 
ed. . This cafe evinces, that the fenfibility of the fyflem to in- 
ternal excitation increafes, as our deep is prolonged; till the 
pain thus occafioned produces voluntary exertion ; which, when 
it is in its ufual degree, only awa-kens us ; but when it is more 
violent, it occafions convulfions. 
The cramp in the calf of the leg is another kind of convul- 
fion, which generally commences in fleep, occafioned by the 
continual increafe of irritability from internal ftimuli, or of fen- 
fibility, during that (late of our exigence. The cramp is a vi- 
olent exertion to relieve pain, generally either of the ikin from 
cold, or of the bowels, as in feme diarrhoeas, or from the muf- 
cles having been previoully overltretched, as in walking up or 
down Reep hills. But in thefe convulfions of the mufcles, which 
form the calf of the leg, the contraction is fo violent as to occa- 
fion another pain in confeq.uence of their own too violent con- 
traCtion, as foon as the original pain, which caufed the contrac- 
tion, is removed. And hence the cramp, or fpafm, of thefe 
mufcles is continued without intermiffion by this new pain, un- 
like the alternate convulfions and remiffions in epileptic fits. 
The reafon, that the contraction of thefe mufcles of the calf of 
the leg is more violent during their convulfion than that of oth» 
ers, depends on the weaknefs of their antagonift mufcles ; for 
after thefe have been contracted in their ufual aCtion, as at every 
ftep in walking, they are again extended, not, as molt other 
mufcles are, by their antagonifis, but by the weight of the whole 
body on the balls of the toes ; and that weight applied to great 
mechanical advantage on the heel, that is, on the other end of 
the bone of the foot, which thus acts as a lever. 
Another difeafe, the periods of which generally commence 
during our fleep, is the althma. Whatever may be the remote 
caufe of paroxyfms of althma, the immediate caufe of the con- 
•vulfive refpiration, whether in the common althma, or in what 
is termed the convulfive althma, which are perhaps only differ- 
ent degrees of the fame difeafe, muft be owing to violent volun- 
tary exertions to relieve pain, as in other convulfions; and the 
increafe 164 
OF SLEEP. 
Sect. XVIII. id. 
jncreafe of irritability to internal ftimuli, or of fcnfibility, during 
fjeep muft occafion them to commence at this time. 
Debilitated people, who have been unfortunately accuftomed 
to great ingurgitation of fpirituous potation, frequently part 
with a great quantity of water during the night, but with not 
more than ufual in the day-time. This is owing to a beginning 
tqrpor of the abforbent fyftem, and precedes anafarca, which 
commences in the day, but is cured in the night by the inoreafe 
of the irritability of the abforbent fyftem during deep, which 
thus imbibes from the cellular membrane the fluids, which had 
Been accumulated there during the day; though it is poflible 
the horizontal pofition of the body may contribute fomething to 
this purpofe, and alfo the greater irritability of fome branches 
of the abforbent veflels, which open their mouths in the cells of 
the cellular membrane, than that of other branches. 
As foon as a perfon begins to fleep, the irritability and fenfi- 
bility of the fyftem begin to increafe, owing to the fufpenfionof 
volition and the exclufion of external ftimuli. Hence the ac- 
tions of the veflels in obedience to internal ftimulation become 
ftronger and more energetic, though lefs frequent in refpeft to 
number. And as many of the fecretions are increafed, fo the 
heat of the fyftem is gradually increafed, and the extremities of 
feeble people, which had been cold during the day, become 
warm. Till towards morning many people become fo warm, as 
to find it neceflary to throw off fome of their bed-clothes, as 
foon as they awake ; and in others fweats are fo liable to occur 
towards morning during their fleep. 
Thus thofe, who are not accuftomed to fleep in the open air, 
Ure very liable to take cold, if they happen to fall afleep on a 
garden bench, or in a carriage with the window open. For as 
the fyftem is warmer during fleep, as above explained, if a cur- 
rent of cold air affects any part of the body, a torpor of that part 
is more effectually produced, as when a cold blaft of air through 
a key-hole or cafement falls upon a perfon in a warm room. In 
thofe cafes the affefted part pofleffes lefs irritability in refpeft to 
heat, from its having previously been expofed to a greater ftim-» 
tilus of heat, as in the warm room, or during fleep ; and hence, 
when the ftimulus of heat is diminifhed, a torpor is liable to en- 
fue; that is, we take cold. Hence people who fleep in the 
open air, generally feel chilly both at the approach of fleep, and 
on their awaking ; and hence many people are perpetually fub- 
jeCt to catarrhs if they fleep in a lefs warm head-drefs, than that 
which they wear in the day. 
16. Not only the fenforial powers of irritation and of ^nft- 
tion, but that of aflcciation alfo appear to aft with greater vig- 
our Sect. XVIII. 16. 
OF SLEEP. 
165 
our during the fufpeniion of volition in fleep. It wilkhe Ihewn 
in another place, that the gout generally firft attacks the liver, 
and that afterwards an inflammation of the ball of the great toe 
commences by aflbciation, and that of the liver ceafes. Now as 
this change or metaftafis of the activity of the fyftem generally 
commences in fleep, it follows, that thefe aflbciations of motion 
exift with greater energy at that time ; that is, that the fenforial 
faculty of aflbciation, like thofeof irritation and of fenfation, be- 
comes in fome meafure accumulated during the fufpeniion of 
volition. 
Other aflbciate tribes and trains of motions, as well as the ir- 
ritative and fenlitive ones, appear to be increafed in their activ- 
ity during the fufpeniion of volition in fleep. As thofe which 
contribute to circulate the blood, and to perform the various 
fecretions; as well as the aflbciate tribes and trains of ideas, 
which contribute to furnifli the perpetual itreams of our dream- 
ing imaginations. 
In fleep the fecretions have generally been fuppofed to be di- 
minifhed, as the expectorated mucus in coughs, the fluids dif- 
charged in diarrhoeas, and in falivation, except indeed the fecre- 
tion of fweat, which is often vifibly increafed. This error 
feems to have arifen from attention to the excretions rather than 
to the fecretions. For the fecretions, except that of fweat, are 
generally received into refervoirs, as the urine into the bladder, 
and the mucus of the inteftines and lungs into their refpcCtive 
cavities ; but thefe refervoirs do not exclude thefe fluids imme- 
diately by their ftimulus, but require at the fame time fome vol- 
untary efforts, and therefore permit them to remain during fleep. 
And as they thus continue longer in thofe receptacles in our 
fleeping hours, a greater part is abforbed from them, and the 
remainder becomes thicker, and fometimes in lefs quantity, 
though at the time it was fecreted the fluid was in greater quan- 
tity than in our waking hours. Thus the urine is higher col- 
oured after long fleep ; which Ihews, that a greater quantity 
has been fecreted, and that more of the aqueous and lahne part 
has been re-abforbed, and the earthy part left in the bladder; 
hence thick urine in fevers fhews only a greater action of the 
veffels which fecrete it in the kidneys, and of thofe which abforb 
it from the bladder. 
The fame happens to the mucus expectorated in coughs, 
which is, thus thickened by abforption of its aqueous and faline 
parts ; and the fame of the faeces of the inteftines. From hence 
it appears, and from what has been faid in No. 15 of this Sec- 
tion concerning the increafe of irritability and of fenfibility du- 
ring fleep, that the fecretions aje in general rather increafed 
than 166 
OF SLEEP. 
Sect. XVIII. 17. 
than dimfirifhed during thefe hours of our exiftence ; and it is 
probable that nutrition is almoft entirely performed in deep ; 
and that young animals grow more at this time than in their 
waking hours, as young plants have long fince been obferved to 
grow more in the night, which is their time of deep. 
17. Two other remarkable circumftances of our dreaming 
ideas are their inconfiftency, and the total abfcnce of furprife. 
Thus we feem to be prefent at more extraordinary metamor- 
phofes of animals or trees, than are to be met with in the fables 
of antiquity ; and appear to be tranfported from place to place, 
which feas divide, as quickly as the changes of feenery are per- 
formed in a play-houfe ; and yet are not fenfible of their in- 
confiftency, nor in the leaft degree afleffed with furprife. 
We muft confider this circumftance more minutely. In our 
waking trains of ideas, thofe that are inconfiftent with the ufual 
order of nature, fo rarely have occurred to us, that their con- 
nexion is the dighteft of all others : hence, when a confiftent 
train of ideas is exhaufted, we attend to the external ftimuli, 
that ufually furround us, rather than to any inconfiftent idea, 
which might otherwife prefent itfelf: and if an inconfiftent 
idea fliould intrude itfelf, we immediately compare it with the 
preceding one, and voluntarily rejeeft the train it would intro- 
duce ; this appears further in the Section on Reverie, in which 
ftate of the mind external ftimuli are not attended to, and yet 
the ftreams of ideas are kept confiftent by the efforts of volition. 
But as our faculty of volition is fufpended, and all external ftim- 
uli are excluded in deep, this dighter connexion of ideas takes 
place ; and the train is faid to be inconfiftent; that is, diflimi- 
lar to the ufual order of nature. 
But, when any confiftent train of fenfitive or voluntary 
ideas is flowing along, if any external ftimulus affects us fo vio- 
lently, as to intrude irritative ideas forcibly into the mind, it 
difunites the former train of ideas, and we are afleefted with fur- 
prife. Thefe ftimuli of unufual energy or novelty not only dif- 
unite our common trains of ideas, but the trains of mufcular mo- 
tions alfo, which have not been long eftablithed by habit, and 
difturb thofe that have. Some people become motionlefs by 
great furprife, the fits of hiccup and of ague have been often re- 
moved by it, and it even affects the movements of the heart, and 
arteries ; but in our deep, all external ftimuli are excluded, and 
in confequence no furprife can exift. See Section XVII. 3. 7. 
18. We frequently awake with pleafure from a dream, which 
has delighted us, without being able to recollect the tranfac- 
tions of it j uniefs perhaps at a diftance of time, fome analogous 
idea may introduce afrclh this forgotten train : and in our wa- 
king Sect. XVIII. 19. 
OF SLEEP. 
167 
king reveries we fometimes in a moment lofe the train rfWrought, 
but continue to feel the glow of pleafure, or the depreifion of 
fpirits, it occafioned : whilft at other times we can retrace with 
cafe thefe hiftories of our reveries and dreams. 
The above explanation of furprife throws light upon this fub- 
ject. When we are fuddenly awaked by any violent ftimulus, 
the furprife totally difunites the trains of our lleeping ideas 
from thofe of our waking onei •, but if we gradually awake* 
this d®es not happen; and we readily unravel the preceding 
trains of imagination. 
19. There are various degrees of furprife ; the more intent 
we are upon the train of ideas, which we are employed about, 
the more violent mult be the ftimulus that interrupts them, and 
the greater is the degree of furprife. I have obferved dogs, who 
have Hept by the fire, and by their obfcure barking and ftrug- 
gling have appeared very intent on their prey, that (hewed great 
furprife for a few feconds after their awaking by looking eagerly 
around them ; which they did not do at other times of waking. 
And an intelligent friend of mine has remarked, that his lady, 
who frequently fpeaks much and articulately in her ileep, could 
never recollect her dreams in the morning, when this happened 
to her: but that when fhe did not fpeak in her fieep, file could 
always recolleft them. 
Hence, when our fenfations act fo ftrongly in deep as to in- 
fluence the larger mufcles, as in thofe, who talk or ftruggle in 
their dreams ; or in thofe, who are affected with complete rev- 
erie (as defcribed in the next Section), great furprife is produ- 
ced, when they awake ; and thefe as well as thofe, who are 
completely drunk or delirious, totally forget afterwards their 
imaginations at thofe times. 
20. As the immediate caufe of fleep confifts in the fufpen- 
fion of volition, it follows, that whatever diminifiies the general 
quantity of fenforial power, or derives it from the faculty of 
volition, will conftitute a remote caufe of fleep ; fuch as fatigue 
from mufcular or mental exertion, which diminifhes the general 
quantity of fenforial power ; or an increafe of the fenfitwe mo- 
tions, as by attending to foft mufic, which diverts the fenforial 
power from the faculty of volition ; or laftly, by increafe of the 
irritative motions, as by wine, or food, or warmth ; which not 
only by their expenditure of fenforial power diminifh the quan- 
tity of volition ; but alfo by their producing pleafurable fenfa- 
tions (which occauon other mufcular or fenfual motions in con- 
fequence), doubly decreafe the voluntary power, and thus more 
forcibly produce fleep. See Se6t. XXXIV. 1. 4. 
Another method of inducing fleep i? delivered in a very mge* 
nious 168 
OF SLEEP. 
Sect. XVIII. 2o. 
nious work lately publiflied by Dr. Beddoes. Who after la- 
menting that opium frequently occafions reflleflhefs, thinks, 
«< that in moll cafes it would be better to induce deep by the 
nbRraClicn of Rimuli, than by exhauRing the excitability and 
adds, " upon this principle we could not have a better foporific 
than an atmofphere with a diminilhed proportion of oxygene 
air, and that common air might be admitted after the patient 
was afieep." (Obferv. on Calculus, &c. by Dr. Beddoes, Mur- 
ray.) If it ihould be found to be true, that the excitability of 
the fyftem depends on the quantity of oxygene abforbed by the 
lungs in refpiration according to the theory of Dr. Beddoes, and 
of M. Girtanner, this idea of deeping in an atmofphere with lefs 
oxygene in its compofition might be of great fervice in epileptic 
cafes, and in cramp, and even in fits of the afthma, where their 
periods commence from the increafe of irritabilitv during deep. 
Sleep is like wife faid to be induced by mechanic prefl'ure on 
the brain in the cafes of fpina bifida. Where there has been 
a defeat of one of the vertebrx of the back, a tumour is protru- 
ded in confequence ; and, whenever this tumour has been com- 
p refled by the hand, deep is faid to be induced, becaufe the 
whole of the brain both within the head and fpine becomes com- 
prefled by the retroceffion of the fluid within the tumour. But 
by what means a compreflion of the brain induces deep has not 
been explained, but probably by diminifhing the fecretion of 
fenforial power, and then the voluntary motions become fuf- 
pended previoufly to the irritative ones, as occurs in moll dying 
perfons. 
Another way of procuring fleep mechanically was related to 
me by Mr. Brindley, the famous canal engineer, who was 
brought up to the bufinefs of a mill-wright ; he told me, that he 
had more than once feen the experiment of a man extending 
himfelf acrofs the large flone of a corn-mill, and that by gradu- 
ally letting the Rone whirl, the man fell asleep, before the Rone 
had gained its full velocity, and he fuppofed would have died 
without pain by the continuance or increafe of the motion. In 
this calc ihe centrifugal motion of the head and feet mufi accu- 
mulate the blood in both thofe extremities of the body, and thus 
comprd's the brain. 
LaRly, we Ihould mention the application of cold; which, 
when in a lefs degree, produces watchfulnefs by the pain it oc- 
cafions, and the tremulous convulfions of the fubcutaneous muf- 
clcs ; but when it is applied in great degree, is faid to produce 
fleep. To explain this effect it has been laid, that as the veflels 
of the fkin and extremities become firR torpid by the want of 
the Rimulus of heat, and as thence lefs blood is circulated 
through Sect. XVIII. 21. 
OF SLEEP. 
169 
through them, as appears from their palenefs, a greater quantity 
of blood poured upon the brain produces deep by its compref- 
fion of that organ. But I fhould rather imagine, that the fenfo- 
rial power becomes exhaufted by the convullive adlions in con- 
fequence of the pain of cold, and of the voluntary exercife pre- 
vioufly ufed to prevent it, and that the deep is only the beginning 
to die, as the fufpenfion of voluntary power in lingering deaths 
precedes for many hours the extintlion of the irritative motions. 
2i. The following are the charadteriftic circumltances at- 
tending perfect deep. 
i. The power of volition is totally fufpended. 
2. The trains of ideas caufed bv fenfation proceed with great- 
er facility and vivacity ; but become inconfident with the ufual 
order of nature. The mufcular motions caufed by fenfation 
continue ; as thofe concerned in our evacuations during infan- 
cy, and afterwards in digeftion, and in priapifmus. 
3. The irritative mufcular motions continue-, as thofe con- 
cerned in the circulation, in fecretion, in refpiration. But the 
irritative fenfual motions, or ideas, are not excited ; as the im- 
mediate organs of fenfe are not ffimulated into adtion by exter- 
nal objedls, which are excluded by the external organs of fenfe; 
which are not in deep adapted to their reception by the power 
of volition, as in our waking hours. 
4. The adbeiate motions continue ; but their firft link is not 
excited into adtion by volition, or by external ftimuli. In all 
refpcdls, except thofe above mentioned, the three left fenforial 
powers are fomewhat increafed in energy during the fufpenfion 
of volition, owing to the confequcnt accumulation of the fpiric 
of animation. 
Vol. I. 
T 
SECT 170 
OF REVERIE. 
Sect. XIX. ii 
SECT. XIX. 
OF REVERIE. 
I. Various degrees of reverie. 2. Sleep-walkers. Cafe of a young 
lady. Great furprife at awaking. And total forgetfulnefs of 
what pa fed in reverie. 3. No fufpetfion of volition in reverie. 
4. Senfitive motions continue, and are confflent. Irritative 
motions continue, but are not fucceeded by fenfation. 6. Volition 
neceffary for the perception of feeble impreffions. y. Affociated mo- 
tions continue. 8. Nerves offenfe are irritable in fieep, but not in 
reverie. 9. Somnambuli are not afeep. Contagion received but 
once. io. Definition of reverie. 
i. When we are employed with great fenfation of pleafure, 
or with great efforts of volition, in the purfuit of feme intereft- 
ing train of ideas, we ceafe to be confcious of our exiftence, 
are inattentive to time and place, and do not diftinguifh this 
train of fenfitive and voluntary ideas from the irritative ones ex- 
cited by the prefence of external objects, though our organs of 
fenfe are furrounded with their accuftomed ftimuli, till at length 
this interelling train of ideas becomes exhaufted, or the appulfes 
of external objects are applied with unufal violence, and we re- 
turn with furprife, or with regret, into the common track of life. 
This is termed reverie or ftudium. 
In fome conftitutions thefe reveries continue a confiderable 
time, and are not to be removed without greater difficulty, but 
are experienced in a lefs degree by us all; when we attend ear- 
neftly to the ideas excited by volition or fenfation, with their af- 
fociated connexions, but are at the fame time confcious at inter- 
vals of the ftimuli of furrounding bodies. Thus in being pref- 
ent at a play, or in reading a romance, fome perfons are fo totally 
abforbed as to forget their ufual time of Heep, and to neglect their 
meals; while others are faid to have been fo involved in volun- 
tary ftudy as not to have heard the difeharge of artillery ; and 
there is a ftory of an Italian politician, who could think fo intenfe- 
ly on other fubjefts, as to be infenfible to the torture of the rack. 
From hence it appears, that thefe catenations of ideas and 
mufcular motions, which form the trains of reverie, are compo- 
fed both of voluntary and fenfitive aflbeiations of them ; and 
that thefe ideas differ from thofe of delirium or of Heep, as they 
are kept confident by the power of volition ; and they differ al- 
fo from the trains of ideas belonging to infanity, as they are as 
frequently excited by fenfatiop as by volition, But laftly, that 
the Sect. XIX. 2. 
OF REVERIE. 
171 
the whole fenforial power is fo employed on thefe trains of com- 
plete reverie, that like the violent, efforts of volition, as in con- 
vulfions or infanity ; or like the great activity of the irritative 
motions in drunkennefs ; or of the fenfitive motions in deliri- 
um ; they preclude all fenfation confequent to external ftimulus. 
2. Thofe perfons, who are faid to walk in their deep, are af- 
fefted with reverie to fo great a degree, that it becomes a for- 
midable difeafe ; the effence of which confifts in the inaptitude 
of the mind to attend to external ftimuli. Many hiftories of 
this difeafe have been publifhed by medical writers ; of which 
there is a very curious one in the Laufanne Tranfadtions. I 
(hall here fubjoin an account of fuch a cafe,'with its cure, for the 
better illuftration of this fubjcct. 
A very ingenious and elegant young lady, with light eyes and 
hair, about the age of feventeen, in other refpe&s well, was fud- 
denly feized foon after her ufual menftruation with this very- 
wonderful malady. The difeafe began with vehement convul- 
fions of almoft every mufcle of her body, with great but vain ef- 
forts to vomit, and the moft violent hiccoughs, that can be 
conceived : thefe were fucceeded in about an hour with a fixed 
fpafm; in which one hand was applied to her head, and the other 
to fupport it: in about half an hour thefe ceafed, and the reverie 
began fuddenly, and was at firft manifeft by the look of her eyes 
and countenance, which feemed to exprefs attention. Then 
(he converfed aloud with imaginary perfons with her eyes open, 
and could not for about an hour be brought to attend to the ftim- 
ulus of external objects by any kind of violence, which it was 
proper to ufe : thefe fymptoms returned in this order every day 
for five or fix weeks. « 
Thefe converfations were quite confident, and we could un- 
derftand, what fhe fuppofed her imaginary companions to anfwer, 
by the continuation of her part of the difeourfe. Sometimes 
fhe was angry, at other times fbewed much wit and vivacity, but 
was moft frequently inclined to melancholy. In thefe reveries 
fhe fometimes fung over fome mufic with accuracy, and repeated 
whole pages from theEnglifh poets. In repeating fome lines from 
Mr. Pope's works fhe had forgot one word, and began again, en- 
deavouring to recollect it; when fhe came to the forgotten word, 
it was fhouted aloud in her ear, and this repeatedly, to no pur- 
pofe ; but by many trials fhe at length regained it herfelf. 
Thefe paroxyfms were terminated with the appearance of in- 
expreflible furprife, and great fear, from which fhe was fome 
minutes in recovering herfelf, calling on her fifter with great ag- 
itation, and very frequently underwent a repetition of convul- 
fions, apparently from the pain of fear. See Seft X.VII. 3. 7. 
After 172 
OF REVERIE. 
Sect. XIX. 3 
After having thus returned for about an hour every day for 
two or three weeks, the reveries feemed to become lefs com- 
plete, and fome of their circumftances varied ; fo that fhe could 
walk about the room in them without running againft any of 
the furniture ; though thcfe motions were at firft very unfteady 
and totlermg. And afterwards fhe once drank a di Hi of tea, when 
the whole apparatus of the tea-table was fet before her 5 and 
exprefled fome fufpicion, that a medicine was put into it, and 
once feemed to fmcll of a tuberofe, which was in flower in her 
chamber, and deliberated aloud about breaking it from the Item, 
faying, « it would make her After fo charmingly angry." At 
another time in her melancholy moments flic heard the found of 
a palling bell, " I with I was dead," fhe cried, liftening to the 
bell, and then taking off one of her (hoes, as fhe fat upon the 
bed, (l I love the colour black," fays fhe, " a little wider, and a 
little longer, even this might make me a coflin !"-Yet it is evi- 
dent, fie was not fenfible at this time, any more than formerly, 
of feeing or hearing any perfon about her ; indeed when great 
light was thrown upon her by opening the {flutters of the win- 
dow, her trains of ideas feemed lefs melancholy ; and when I 
have forcibly held her hands, or covered her eyes, (lie appeared 
to grow impatient, and would fay, (he could not tell what to do, 
for fhe could neither fee nor move. In all thefe circumftances 
her pulfe continued unaffeiSled as in health. And when the par- 
oxyfm was over, (he could never recollect a Angle idea of what 
had pafled in it. 
This aftonilhing difeafe, after the ufe of many other medi- 
cines and applications in vain, was cured by very large dofes of 
opium given about an hour before the expected returns of the 
pardxyfms ; and after a few relapfes, at the intervals of three 
or four months, entirely difappeared. But (he continued at 
times to have other fymptoms of epilepfy. 
3. We (hall only here confider, what happened during the 
time of her reveries, as that is our prefent fubjcT ; the fits of 
convulAoh belong to another part of this treatife. Se£i. XXXIV. 
44^ 
There feems.to have been no fupenfionof volition during the 
fits of reverie, becauie the endeavoured to regain the loll idea in 
repeating the lyres cf poetry, and deliberated about breaking the 
tuberofe, and lufpe&ed the tea to have been medicated. 
4. The ideas and mufcular movements depending on fenfa- 
fation were exerted with their ufual vivacity, and were kept 
from being inccnfiftent by the power of volition, as appeared 
from her whole converfation, and was explained in Sect. XVII. 
3. 7. and XVIII. 16. . 
5. The Sect. XIX. 5. 
OF REVERIE, 
173 
The ideas and motions dependent on irritation during the 
flrlt weeks of her difeafe, whilft the reverie was complete, w^re 
never fucceeded by the fenfation of pleafure or pain; as fhe 
neither law, heard, nor felt any of the furrounding objects. 
Nor was it certain that any irritative motions fucceeded the ftim- 
ulus.of external objeiSts, till the reverie became lefs complete, 
and then me could walk about the room without running agaiml 
the furniture of it. Afterwards, when the reverie became ftill 
kfs complete from the ufe of opium, fome few irritations were at 
times fucceeded by her attention to them. As when ihe fmelt 
at a tuberofe, and drank a difh of tea, but this only when ihe 
feemed voluntarily to attend to them. 
6. In common life when we liften to diftant founds, or with 
to diftinguifh objects in the night, we are obliged flrongly to 
exert our volition to difpofe the organs of fcnfe to perceive them, 
and to fupprefs the other trains of ideas, which' might interrupt 
thefe feeble fenfations. Hence in the prefent hiftory the ftrong- 
eft llimuli were not perceived, except when the faculty of voli- 
tion was exerted on the Organ of fenfe j and then even com- 
mon llimuli were fometimes perceived : for her mind was fa 
ftrenuoufly employed in purfuingit? own trains of voluntary or 
fenfitive ideas, that no common Ibmuli could lb far excite her 
attention as to difunite them ; that is, the quantity of volition or 
of fenfation already exifting was greater than any, which could 
be produced in confequence of common degrees of ftimulation. 
But the few ftimuli of the tuberofe, and of the tea, which Ihe 
did perceive, were fuch, as accidentally coincided with the trains 
of thought, which were palling in her mind ; and hence did not 
difunite thofe trains, and create furprife. And their being per- 
ceived at all was owing to the power of volition preceding or 
coinciding with that of irritation. 
This explication is countenanced by a fact mentioned con- 
cerning a fomnambulift in the Laufanne Tranfaftions, who 
fometimes. opened his eyes for a fhort time to examine, where 
he was, or where his ink-pot flood, and then flint them again, 
dipping his pen into the pot every now and then, and writing 
on, but never opening his eyes afterwards, although he wrote 
on from line to line regularly, and corrected fome errors of the 
pen, or in fpelling: fo much eafier was it to him to refer to his. 
ideas of the pofitions of things, than to his perceptions of them. 
7. The alfociated motions perfifted in their ufual channel, as 
appeared by the combinations of her ideas, and the ufe of her 
mufcles, and the equality of her pulfe ; for the natural motions 
of the arterial fyllem, though originally excited like other mo- 
tions by Rimu^s, feem in part K> continue by their affbeiation 
* with 174 
OF REVERIE. 
Sect. XIX. 8. 
with each other. As the heart of a viper pulfates long after it 
is cut out of the body, and removed from the ftimulus of the 
blood. 
8. In the feftion on Deep, it was obferved that the nerves of 
fenfe are equally alive and fufceptible to irritation in that Hate, 
as when we are awake ; but that they are fecluded from ftimu- 
lating objects, or rendered unfit to receive them : but in com- 
plete reverie the reverfe happens, the immediate organs of fenfe 
are expofed to their ufual ftimuli; but are either not excited into 
action at all, or not into fo great action, as to produce attention 
or fenfation. 
The total forgetfulnefe of what paffes in reveries; and the 
furprife on recovering, from them, are explained in Section 
XVIII. 19. and in Seclion XVII. 3. 7. 
9. It appears from hence, that reverie is a difeafe of the epilep- 
tic orcataleptic kind, fince the paroxyfmsofthis young lady always 
began and frequently terminated withconvulfions; and though in 
its greateft degree it has been called fomnambulation, or fleep- 
walking, it is totally differentfrom fleep; becaufethe eflential char- 
after of fleep con lifts in a total fufpenfion of volition, which in 
reverie is not affefted ; the eflential character of reverie confifts 
not in the abfence of thofe irritative motions of our fenfes, 
which are occafioned by the ftimulus of external objects, but in 
their never being productive of fenfation. So that during a fit 
of reverie that ftrange event happens to the whole fyftem of 
nerves, which occurs only to fome particular branches of them 
in thofe, who are a fecond time expofed to the aftion of conta- 
gious matter. If the matter of the fmall-pox be inferted into 
the arm of one, who has previoufly had that difeafe, it will 
ftimulate the wound, but the general fenfation or inflammation 
of the fyftem does not follow, which conftitutes the difeaf<^< 
See Sect. XII. 7. 6. XXXIII. 2. 8. v 
10. The following is' the definition or character of complete 
reverie. 1. The irritative motions occafioned by internal fti- 
muli continue, thofe from the ftimuli of external objefts are ei- 
ther not produced at all, or are never fucceeded by fenfation or 
attention, unlefs they are at the fame time excited by volition. 
2. The fenfitive motions continue, and are kept confident by the 
power of volition. 3. The voluntary motions continue undif- 
turbed. 4. The aflbeiate motions continue undifturbed. 
Two other cafes of reverie are related in Section XXXIV. 3. 
which further evince, that reverie is an effort'of the mind to re- 
lieve fome painful fenfation, and is hence allied to convulfion, 
and to iafanity. Another cafe is related in Clafs III. 1. 2. 2. 
4 &iCT, Sect. XX. 1.' 
OF VERTIGO. 
175 
SECT. XX. 
OF VERTIGO. 
I. We determine our perpendicularity by the apparent motions of ob- 
jects. A perfon hood-winked cannot walk in a fraight line. 
Dizzinefs on laokingfrom a tower, in a room flained with uni- 
form lozenges $ on riding over fnow. 2. Dizzinefs from moving 
objedls. A whirling wheel. Fluctuations of a river. Experi- 
ment with a child. 3. Dizzinefs from our own motions and 
thofe of other objects. Riding over a broadfream. Seafcknefs. 
5. Of turning round on one foot. Dervifes in Turkey. Atten- 
tion of the mind prevents fight feafeknefs. After a voyage ideas 
of vibratory motions are f ill perceived on fore. 6. Ideas con- 
tinue fome time after they are excited. Circumfances of turning 
on one foot, fanding on a tow er, and walking in the dark, explain- 
ed. 7. Irritative ideas of apparent motions. Irritative ideas of 
founds. Battemens of the found of bells and organ-pipes. Ver- 
tiginous noife in the head. Irritative motions of the fomach, in- 
tefines, and glands. 8. Symptoms that accompany vertigo. Why 
vomiting comes on in frokes of the palfy. By the motion of a flip. 
By injuries on the head. Why motion makes fek people vomit. 
9. Why drunken people are vertiginous. Why a fone in the ure- 
ter or bile-dud, produces vomiting. 1 o. Why after a voyage 
ideas of vibratory motions are perceived on Jhore. 11. Kinds of 
vertigo and their cure. I2« Def nition of vertigo. 
I. In learning to Walk we judge of the distances of the ob- 
jefts, which we approach, by the eye; and by obferving their 
perpendicularity determine our own. This circumftance not 
having been attended to by the writers on vifion, the difeafe 
called vertigo or dizzinefs has been little underftood. 
When any perfon Idfes the power of mufcular action, wheth- 
er he is erect or in a fitting pofture, he finks down upon the 
ground ; as is feen in fainting fits, and other inftances of great 
debility. Hence it follows, that fome exertion of mufcular pow- 
er is neceffary to preferve our perpendicular attitude. This is 
performed proportionally exerting the antagonift mufdes of the 
trunk, neck, and limbs; and if at^any time in our locomotions 
we find ourfelves inclining to one fide, we either reftore our 
equilibrium by the efforts of the mufcles on the othenfide, or 
by moving one of our feet extend the bafe, which we reft upon, 
to the new centre of gravity. 
But the meft eafy and habitual manner of determining our 
want 176 
OF VERTIGO. 
Sect. XX. 2. 
want of perpendicularity, is by attending to the apparent mo- 
tion of the objects within the fphere of oiftindt vifion ; for this 
apparent motion of objects, when we incline from our perpen- 
dicularity, or begin to fall, is as much greater than the real mo- 
tion of the eye, as the diameter of the fphere of diftintt vifion is 
to our perpendicular height. 
Hence no one, who is hood-winked, can walk in a ftraight 
line for a hundred fteps together; for he inclines fo greatly, 
be'ore he is warned of his want of perpendicularity by the fenfe 
of touch, not having the apparent motions of ambient objects 
to meafure this inclination by, that he is neceflitated to move 
one of his feet outwards, to the right or to the left, to fupport 
the new centre of gravity, and thus errs from the line he en- 
deavours to proceed in. 
For the fame reafon many people become dizzy, when they 
look from the fummit of a tower, which is raifed much above 
all other objects, as thefe objects are out of the fphere of dif- 
tinct vifion, and they are obliged to balance their bodies by the 
lefs accurate feelings of their mufclcs. 
There is another curious phenomenon belonging to this place, 
if the circumjacent vifible objects are fo fmall, that we do not 
diftinguifh their minute parts ; or fo fimilar, that we do not 
know them from each other; we cannot determine our perpen- 
dicularity by them. Thus in a room hung with a paper, which 
is coloured over with fimilar fmall black lozenges or rhomboids, 
many people become dizzy; for when they begin to fall, the 
next and the next lozenge fucceeds upon the eye; which they mif- 
take for the firft, and are not aware, that they have any apparent 
motion. But if you fix a fheet of paper, or draw any other fig- 
ure, in the midft or thefe lozenges, the charm ceafes, and no 
dizzinefs is perceptible.-The fame occurs, when we ride over 
a plain covered with fnow without trees or other eminent objects. 
2. But after having compared vifible objects at reft with the 
fenfe of touch, and learnt to diftinguilh their ihapes and (hades, 
and to meafure our want of perpendicularity by their apparent 
motions, we come to confider them in real motion. Here a new 
dilficulty occurs, and we require fome experience to learn the 
peculiar mode of motion of any moving objects, before we can 
make ufc of them for the purpofes of determining our perpen- 
dicularity. Thus fome people become dizzy at the fight of a 
whirling wheel, or by gazing on the fluctuations of a river, if 
no fteady objects are at the fame time within the fphere of their 
diftinft vifion ; and when a child firft can (land eredt upon his 
iegs, if you gain his attention to a white handkerchief fteadily 
extended like a fail, and afterwards make it undulate, he in- 
ftantly Sect. XX. 3. 
OF VERTIGO. 
177 
ftantly lofes his perpendicularity, and tumbles on the ground. 
3. A fecond difficulty we have to encounter is to diftinguiffi 
our own real movements from the apparent motions of objects. 
Our daily practice of walking and riding on horfeback foon in- 
ftrufts us with accuracy to difcern thefe modes of motion, and 
to afcribe the apparent motions of the ambient objects to our- 
felves ; but thofe, which we have have not acquired by repeated 
habit, continue to confound us. So as we ride on horfeback the 
trees and cottages, which occur to us, appear at reft ; we can 
meafure their diftances with our eye, and regulate our attitude 
by them ; yet if we carelefsly attend to diftant hills or woods 
through a thin hedge, which is near us, we obfervethe jumping 
and progreffive motions of them; as this is increafed by the 
parallax of thefe objects; which we have not habituated our- 
felves to attend to. When firft an European mounts an ele- 
phant fixteen feet high, and whofe mode of motion he is not 
accuftomed to, the objects feem to undulate, as he pafles, and 
he frequently becomes fick and vertiginous, as I am well inform- 
ed. Any other unufual movement of our bodies has the fame 
as riding backwards in a coach, fwinging on a rope, turn- 
ing round fwiftly on one leg, fcating on the ice, and a thoufand 
others. So after a patient has been long confined to his bed, 
when he firft attempts to walk, he finds himfelf vertiginous, and 
is obliged by practice to learn again the particular modes of the 
apparent motions of objects, as he walks by them. 
4. A third difficulty, which occurs to us in learning to balance 
ourfelves by the eye, is, when both ourfelves and the circumja- 
cent objects are in real motion. Here it is neceflary, that we 
ffiould be habituated to both thefe modes of motion in order to 
preferve our perpendicularity. Thus on horfeback we accurately 
obferve another perfon, whom we meet, trotting towards us, 
without confounding his jumping and progreffive motion with 
our own, becaufe we have been accuftomed to them both; that 
is, to undergo the one, and to fee the other at the fame tim^. 
But in riding over a broad and fluctuating ftream, though we 
are well experienced in the motions of our horfe, we are liable 
to become dizzy from our inexperience in that of the water. 
And when firft we go on (hip-board, where the movements of 
ourfelves, and the movements of the large waves are both new 
to us, the vertigo is almoft unavoidable with the terrible fick- 
nefs, which attends it. And this I have been afiured has hap- 
pened to feveral from being removed from a large (hip into a 
fmall one ; and again from a fmall one into a man of war. 
5. From the foregoing examples it is evident, that, when we 
are furrounded with unufual motions, we lofe our perpendicu- 
Vol. I. Z larity: 178 
OF VERTIGO. 
Sect. XX. 5. 
larity : but there are Tome peculiar circumftances attending this 
effeCt of moving objects, which we come now to mention, and 
(hall hope from the recital of them to gain fome infight into the 
manner of their production. 
When a child moves round quick upon one foot, the circum- 
jacent objeCts become quite indiftinCt, as their diltance increafes 
their apparent motions ; and this great velocity confounds both 
their forms, and their colours, as is feen in whirling round a 
many coloured wheel; he then lofes his ufual method of bal- 
ancing himfelf by vifion, and begins to ftagger, and attempts to 
recover himfelf by his mufcular feelings. This ftaggering adds 
to the inftability of the vifible objeCls by giving a vibratory mo- 
tion befides their rotatory one. The child then drops upon the 
ground, and the neighbouring objeCls feem to continue for fome 
feconds of time to circulate around him, and the earth under 
him appears to librate like a balance. In fome feconds of time 
thefe fenfations of a continuation of the motion of objeCls van- 
ifh ; but if he continues turning round fomewhat longer, before 
he falls, ficknefs and vomiting are very liable to fucceed. But 
none of thefe circumftances affeCt thofe who have habituated 
themfelves to this kind of motion, as the dervifes in Turkey, 
amongft whom thefe fwift gyrations are a ceremony of religion. 
In an open boat palling from Leith to Kinghorn in Scotland, 
a fudden change of the wind ftiook the undiftended fail, and 
ftopt our boat ; from this unufual movement the paffengers all 
vomited except myfelf. I obferved, that the undulation of the 
(hip, and the inftability of all vifible objeCls, inclined me ftrongly 
to be fick; and this continued or increafed, when I clofed my 
eyes, but as often as I bent my attention with energy on the 
management and mechanifm of the ropes and fails, the ficknefs 
ceafed ; and recurred again, as often as I relaxed this attention ; 
and I am allured by a gentleman of obfervation and veracity, 
that he has more than once obferved, when the veifel has been in 
immediate danger, that the fca-ficknefs of the pafleugers has in- 
ftantaneoufly ceafed, and recurred again, when the danger was 
over. 
Thofe, who have been upon the water in a boat or (hip fo 
long, that they have acquired the neceffary habits of motion up- 
on that unftable element, at their return on land frequently 
think in their reveries, or between fleeping and waking, that 
they obferve the room, they lit in, or fome of its furniture, to 
librate like the motion of the veifel. This I have experienced 
myfelf, and have been told, that after long voyages, it is fome 
time before thefe ideas entirely vanifti. The fame is obfervable 
in a lefs degree after having travelled fome days in a ftage coach, 
and Sect. XX. 6. 
OF VERTIGO. 
179 
and particularly when we lie down in bed, and compofe our- 
felves to ileep ; in this cafe it is obfervable, that the rattling noife 
of the coach, as well as the undulatory motion, haunts us. The 
drunken vertigo, and the vulgar cuftom of rocking children, will 
be confidered in the next Section. 
6. The motions, which are produced by the power of voli- 
tion, may be immediately flopped by the exertion of the fame 
power on the antagonift mufcles; otherwife thefe with all the 
other clafles of motion continue to go on, fome time after they 
are excited, as the palpitation of the heart continues after the 
object of fear, which occafioned it, is removed. But this cir- 
cumftance is in no clafs of motions more remarkable than in 
thofe dependent on irritation; thus if any one looks at the fun, 
and then covers his eyes with his hand, he will for many feconds 
of time perceive the image of the fun marked on his retina : a 
fimilar image of all other vifible objects would remain fome time 
formed on the retina, but is extinguifhed by the perpetual change 
of the motions of this nerve in our attention to other obje&s. To 
this muft be added, that the longer time any movements have 
continued to be excited without fatigue to the organ, the longer 
will they continue fpontaneoufly, after the excitement is with- 
drawn : as the tafte of tobacco in the mouth after a perfon has 
been fmoking it. This tafte remains fo ftrong, that if a perfon 
continues to draw air through a tobacco pipe in the dark, after 
having been fmoking fome time, he cannot diftinguifh whether 
his pipe be lighted or not. 
From thefe two confiderations it appears, that the dizzinefs 
felt in the head, after feeing objects in unufual motion, is no 
other than a continuation of the motions of the optic nerve ex- 
cited by thofe objects, and which engage our attention. Thus 
on turning round on one foot, the vertigo continues for fome 
feconds of time after the perfon is fallen on the ground; and 
the longer he has continued to revolve, the longer will continue 
thefe fucceflive motions of the parts of the optic nerve. 
After revolving with your eyes open till you become vertig- 
inous, as foon as you ceafe to revolve, not only the circumambi- 
ent objects appear to circulate round you in a dire€lion contrary 
to that, in which you have been turning, but you are liable to 
roll your eyes forwards and backwards ; as is well obferved, 
and ingenioufly demonftrated by Dr. Wells in a late publication 
on vifion. The fame occurs, if you revolve with your eyes 
clofed, and open them immediately at the time of your ceafmg 
to turn; and even during the whole time of revolving, as may 
be felt by your hand prefled lightly on your clofed eyelids. To 
thefe movements of the eyes, of which he fuppofes the obferver 
to 180 
OF VERTIGO. 
Sect. XX. 6. 
to be inconfeious, Dr. Wells afcribes the apparent circumgyra- 
tion of objects on ceafing to revolve. 
The caufe of thus turning our eyes forwards, and then back 
again, after our body is at reft, depends, I imagine, on the fame 
circumftance, which induces us to follow the indiftinfl fpeftra, 
which are formed on one fide of the centre of the retina, when 
we obferve them apparently on clouds, as defcribed in Se&. XL. 
2. 2; and then not being able to gain a more diftinft vifion of 
them, we turn our eyes back, and again and again purfue the fly- 
ing (hade. 
But this rolling of the eyes, after revolving till we become 
vertiginous, cannot caufe the apparent circumgyration of objects, 
in a direction contrary to that in which we have been revolv- 
ing, for the following reafons. i. Becaufe in purfuing a fpec- 
trum in the iky, or on the ground, as above mentioned, we per- 
ceive no retrograde motions of objeds. 2. Becaufe the appar- 
ent retrograde motions of objects, when we have revolved till 
we are vertiginous, continues much longer than the rolling of 
the eyes above defcribed. 
3. When we have revolved from right to left, the apparent 
motion of objects, when we ftop, is from left to right; and 
when we have revolved from left to right, the apparent circula- 
tion of objects is from righuto left: yet in both thefe cafes the 
eyes of the revolver are feen equally to roll forwards and back- 
wards. 
4. Becaufe this rolling of the eyes backwards and forwards 
takes place during our revolving, as may be perceived by the 
hand lightly prefled on the clofed eyelids, and therefore exifts 
before the effect afcribed to it. 
And fifthly, I now come to relate an experiment, in which the 
rolling of the eyes does not take place at all after revolving, and 
yet the vertigo is more diftrefling than in the fituations above 
mentioned. If any one looks fteadily at a fpot in the ceiling 
over his head, or indeed at his own finger held up high over his 
head, and in that fituation turns round till he becomes giddy ; 
and then ftops, and looks horizontally; he now finds, that the 
apparent rotation of obje&s is from above downwards, or from 
below upwards; that is, that the apparent circulation of objects 
is now vertical inftead of horizontal, making part of a circle round 
the axis of his eye ; and this without any rolling of his eyeballs. 
The reafon of there being no rolling of the eyeballs perceived 
after this experiment, is, becaufe the images of objects are form- 
ed in rotation round the axis of the eye, and not from one fide 
to the other of the axis of it; fo that, as the eyeball has not 
power to turn in its focket round its own axis, it cannot follow 
the Sect. XX. 6. 
OF VERTIGO. 
181 
the apparent motions of thefe evanefcent fpeftra, either before 
or after the body is at reft. From all which arguments it is 
manifeft, that thefe apparent retrograde gyrations of objects are 
not caufed by the rolling of the eyeballs ; firft, becaufe no ap- 
parent retrogreffion of objects is obferved in other rollings of 
the eyes. Secondly, becaufe the apparent retrogreffion of ob- 
jects continues many feconds after the rolling of the eyeballs 
ceafes. Thirdly, becaufe the apparent retrogreffion of objects is 
fometimes one way, and fometimes another, yet the rolling of 
the eyeballs is the fame. Fourthly, becaufe the rolling of the 
eyeballs exifts before the apparent retrograde motions of objects 
is obferved ; that is, before the revolving perfon ftops. And 
fifthly, becaufe the apparent retrograde gyration of obje&s is 
produced, when there is no rolling of the eyeballs at all. 
Doftor Wells imagines, that no fpedtracan be gained in the 
eye, if a perfon revolves with his eyelids clofed, and thinks this 
a fufficient argument againft the opinion, that the apparent pro- 
greffion of the fpedlra of light or colours in the eye can caufe 
the apparent retrogreffion of objects in rhe vertigo above defcri- 
bed ; but it is certain, when any perfon revolves in a light room 
with his eyes clofed, that he neverthelefs perceives differences of 
light both in quantity and colour through his eyelids, as he turns 
round; and readily gains fpedtra of thofe differences. And thefe 
fpeftra are not very different except in vivacity from tKofe, which 
he acquires, when he revolves with uncloi'ed eyes, fince if he 
then revolves very rapidly the colours and forms of furrounding 
objects are as it were mixed together in his eye; as when the 
prifmatic colours are painted on a wheel, they appear white as 
they revolve. The truth of this is evinced by the ftaggering or 
vertigo of men perfectly blind, when they turn round ; which 
is not attended with apparent circulation of objects, but is a ver- 
tiginous diforder of the fenfe of touch. Blind men balance them- 
felves by their fenfe of touch j which, being lefs adapted for 
perceiving fmall deviations from their perpendicular, occafions 
them to carry themfelves more ereft in walking. This method 
of balancing themfelves by the direction of their preffure againft 
the floor, becomes difordered by the unufual mode of action in 
turning round, and they begin to lofe their perpendicularity, 
that is, they become vertiginous ; but without any apparent cir- 
cular motions of vifible objects. 
It will appear from the following experiments, that the appar- 
ent progreffibn of the occular fpedtra of light or colours is the 
caufe of the apparent retrogreffion of objects, after i perfon has 
revolved, till he is vertiginous. 
Firft, when a perfon turns round in a light room with his 
eyes 182 
OF VERTIGO. 
Sect. XX. 6. 
eyes open, but clofes them before he flops, he will feem to be 
carried forwards in the direction he was turning for a fhort time 
after he flops. But if he opens his eyes again, the objects before 
him inftantly appear to move in a retrograde direction, and he 
lofes the fenfation of being carried forwards. The fame occurs 
if a perfon revolves in a light room with his eyes clofed; when 
he flops, he feems to be for a time carried forwards, if his eyes 
are Rill clofed; but the inflant he opens them, the furrounding 
objects appear to move in retrograde gyration. From hence it 
may be concluded, that it is the fenfation or imagination of our 
continuing to go forwards in the direRion in which we were 
turning, that caufes the apparent retrograde circulation of ob- 
jefts. 
Secondly, though there is an audible vertigo, as is known bv 
the battement, or undulations of found in the ears, which many 
vertiginous people experience ; and though there is alfo a tangi- 
ble vertigo, as when a blind perfon turns round, as mentioned 
above ; yet as this circumgyration of objetls is an hallucination 
or deception of the fenfe of fight, we are to look for the caufe 
of our appearing to move forward, when we flop with our eyes 
clofed after gyration, to fome affection of this fenfe. Now, 
thirdly, if the fpedtra formed in the eye during our rotation con- 
tinue to change, when we Hand Hill, like the fpedlra defcribed 
in Seel. III. 3. 6- fuch changes muff fuggeft to us the idea or 
fenfation of our Hill continuing to turn round ; as is the cafe, 
when we revolve in a light room, and clofe our eyes before we 
flop. And laftly, on opening our eyes in the fituation above 
defcribed, the objedls we chance to view amid thefe changing 
fpeRra in the eye, mutt feem to move in a contrary direction ; 
as the moon fometimes appears to move retrograde,' when fwift- 
gliding clouds arc palling forwards fo much nearer the eye of 
the beholder. 
To make obfervations on faint occular fpeclra requires fome 
degree of habit, and compofure of mind, andeven patience ; fome 
of thofe defcribed in fe£l. XL. were found difficult to fee, by 
many, who tried them ; now it happens, that the mind, during 
the confufion of vertigo, when all the other irritative tribes of 
motion, as well as thofe of vifion, are in fome degree difturbed, 
together with the fear of falling, is in a very unfit (late for the 
contemplation of fuch weak fenfations, as are occafioned by faint 
occular fpeblra. Yet after frequently revolving, both with my 
eyes clofed, and with them open, and attending to the fpedlra 
remaining in them, by (hading the light from my eyelids more 
or lefs with my band, I at length ceafed to have the idea of going 
forward, after I Hopped with my eyes clofed ; and faw changing 
fpeclra Sect. XX. 6. 
OF VERTIGO, 
183 
fpedlra in my eyes, which feemed to move, as it were, over the 
field of vifion j till at length, by repeated trials on funny days, 
I perfuaded myfelf, on opening my eyes, after revolving fome 
time, on a Ihelf of gilded books in my library, that I could per- 
ceive the fpeclra in my eyes move forwards over one or two of 
the books, like the vapours in the air of a fummer's day ; and 
could fo far undeceive myfelf, as to perceive the books to ftand 
Rill. After more trials I fometimes brought myfelf to believe, 
that I faw changing fpeflra of lights and (hades moving in my 
eyes, after turning round for fome time, but did not imagine 
either the fpeiflra or the objects to be in a (late of gyration. I 
fpeak, however, with diffidence of thefe fadls, as I could not al- 
ways make the experiments fucceed, when there was not a ftrong 
light in my room, or when my eyes were not in the molt proper 
ftate for fuch obfervations. 
Fhe ingenious and learned M. Sauvage has mentioned other 
theories to account for the apparent circumgyration of objects in 
vertiginous people. As the retrograde motions of the particles 
of blood in the optic arteries, by fpafm, or by fear, as is feen in 
the tails of tadpoles, and membranes between the fingers of frogs. 
Another caufe he thinks may be from the librations to one fide, 
and to the other, of the cryilalline lens in the eye, by means of 
involuntary actions of the mufcles, which conftitute the ciliary 
procefs. Both thefe theories lie under the fame objection as 
that of Dr. Wells before mentioned ; namely, that the apparent 
motions of objects, after the obferver has revolved for fome time, 
fhould appear to vibrate this way and that; and not to circulate 
uniformly in a direction contrary to that, in which the obferver 
had revolved. 
M. Sauvage has, laftly, mentioned the theory of colours left in 
the eye, which he has termed impreffions on the retina. He fays, 
« Experience teaches us, that imprellions made on the retina by 
a vifible objeft remain fome feconds after the object is removed ; 
as appears from the circle of fire which we fee, when a fire-ltick 
is whirled round in the dark ; therefore when we are carried 
round our own axis in a circle, we undergo a temporary vertigo, 
when we (top ; becaufe the imprelTicfns of the circumjacent ob- 
jedls remain for a time afterwards on the retina." Nofolog. 
Method. Claf. VIII. i. i. We have before obferved, that the 
changes of thefe colours remaining in the eye, evinces them to 
be motions of the fine terminations of the retina, and not impref- 
fions on it; as imprellions on a paflive fubftance muft either re- 
main, or ceafe intirely. 
Having reperufed the ingenious Eflay of Dr. Wells on Single 
Vifion, and his additional obfervations in the Gentleman's Mag- 
azine 184 
OF VERTIGO. 
Sect. XX. 6. 
azine on the apparent retrogreflion of objects in vertigo, I am 
induced to believe, that this apparent retrogrelhon of objects is 
not always owing to the fame caufe. 
When a perfon revolves with his eyes clofed, till he becomes 
vertiginous, and then Rands Rill without opening them, he feems 
for a while to go forward in the fame direction. This halluci- 
nation of his ideas cannot be owing to occular fpectra, becaufe, 
as Dr. Wells obferves, no fuch can have been formed ; but it 
muR arile from a fimilar continuance or repetition of ideas be- 
longing to the fenfe of touch, inRead of to the fenfe of vifion ; 
and Riould therefore be called a tangible, not a vifual, vertigo. 
In common language this belief of continuing to revolve for 
fome time, after he Rands Rill, when a perfon has turned round 
for a minute in the dark, would be called a deception of imagin- 
ation. 
Now at this time if he opens his eyes upon a gilt book, placed 
with other books on a flielf about the height of his eye, the gilt 
book feems to recede in the contrary direction; though his eyes 
are at this time kept quite Rill, as well as the gilt book. For 
if his eyes were not kept Rill, other books would fall on them in 
fuccelfion ; which, when I repeatedly made the experiment, did 
not occur ; and which thus evinces, that no motion of the eyes 
is the caufe of the apparent retroceflion of the gilt book. Why 
then does it happen ?-Certainly from an hallucination of ideas, 
or in common language the deception of imagination. 
The vertiginous perfon Rill imagines, that he continues to re- 
volve forwards, after he has opened his eyes ; and in confe- 
quence that the objects, which his eyes happen to fall upon, are 
revolving backward ; as they would appear to do, if he was ac- 
tually turning round with his eyes open. For he has been ac- 
cuRomed to obferve the motions of bodies, whether apparent or 
real, fo much more frequently by the eye than by the touch ; that 
the prefent belief of his gyration, occafioned by the hallucina-\ 
tions of the fenfe of touch, is attended with ideas of fuch imag- 
ined motions of vifible objects, as have always accompanied his 
former gyrations, and have thus been afibciated with the mufcu- 
lar actions and perceptions of touch, which occurred at the 
fame time. 
When the remains of colours are feen in the eye, they are 
termed occular fpectra ; when remaining founds are heard in 
the ear, they may be called auricular murmurs ; but when the re- 
maining motions, or ideas, of the fenfe of touch continue, as in 
this vertigo of a blind-folded perfon, they have acquired no name, 
but may be termed evanefeent titillations, or tangible hallucina- 
tions. 
Whence Sect. XX. 6. 
OF VERTIGO. 
185 
Whence I conclude, that vertigo may have for its caufe ei- 
ther the occular fpe<5tra of the fenfe of vifion, when a perfon 
revolves with his eyes open ; or the auricular murmurs of the 
fenfe of hearing, if he is revolved near a cafcade ; or the evanef- 
cent titillations of the fenfe of touch, if he revolves blindfold. 
All thefe I fhould with to call vanishing ideas,or fenfual motions, 
of thofe organs of fenfe; which ideas, or fenfual motions, have 
lately been affociated in "a circle, and therefore for a time con- 
tinue to be excited. And what are the ideas of colours, when 
they are excited by imagination or memory, but the repetition 
of finer occular fpe&ra ? What the idea of founds, but the repe- 
tition of finer auricular murmurs ? And what the ideas of tangi- 
ble objects, but the repetition of finer evanefeent titillations ? 
The tangible, and the auricular, and the vifual vertigo, are all 
perceived by many people for a day or two after long travelling 
in a boat or coach; the motions of the veffel, or vehicle, or of 
the furrounding objects, and the noife of the wheels and oars, 
occur at intervals of reverie, or at the commencement of deep. 
See SeCt. XX. 5. Thefe ideas, or fenfual motions, of fight, of 
hearing, and of touch, are fucceeded by the fame effects as the 
occular fpe&ra, the auricular murmurs, and the evanefeent titil- 
lations above mentioned ; that is, by a kind of vertigo, and can- 
not in that refpedi be diftinguifhed from them. Which is a fur- 
ther confirmation of the truth of the doctrine delivered in Sedf. 
III. of this work, that the colours remaining in the eyes, which 
are termed occular fpeClra, are ideas, or fenfual motions, belong- 
ing to the fenfe of vifion, which for too long a time continue 
their activity. 
Any one, who ftands alone on the top of a high tower, if he 
has not been accuftomed to balance himfelf by objects placed at 
fuch diftances and with fuch inclinations, begins to (tagger, and 
endeavours to recover himfelf by his mufcular feelings. During 
this time the apparent motion of objects at a diftance below him 
is very great, and the fpeftra of thefe apparent motions continue 
a little time after he has experienced them; and he is perfuaded 
to incline the contrary way to counteract their effects; and 
either immediately falls, or applying his hands to the building, 
ufes his mufcular feelings to preferve his perpendicular attitude, 
contrary to the erroneous perfuafions of his eyes. Whillt the 
perfon, who walks in the dark, (taggers, but without dizzinefs ; 
for he neither has the fenfation of moving objects to take off his 
attention from his mufcular feelings, nor has he the fpeCtra of 
thofe motions continued on his retina to add to his confufion. 
It happens indeed fometimes to one (landing on a tower, that 
the idea of his not having room to extend his bafe by moving 
Vol. I. A a one 186 
OF VERTIGO. 
Sect. XX. 7. 
one of his feet outwards, when he begins to incline, fuperadds 
fear to his other inconveniencies j which like furprife, joy, or 
any great degree of fenfation, enervates him in a moment, by 
employing the whole fenforial power, and by thus breaking all 
the aflbciated trains and tribes of motion. 
7. The irritative ideas of objects, whilft we are awake, arc 
perpetually prefent to our fenfe of fight; as we view the furni- 
ture of our rooms, or the ground we tread upon, throughout the 
whole day without attending to it. And as our bodies are never 
at perfect reft during our waking hours, thefe irritative ideas of 
objetls are attended perpetually with irritative ideas of their ap- 
parent motions. The ideas of apparent motions are always ir- 
ritative ideas, becaufe we never attend to them, whether we at- 
tend to the objebfs themfelves, or to their real motions, or to 
neither. Hence the ideas of the apparent motions of objecfts are 
a complete circle of irritative ideas, which continue throughout 
the day. 
Alfo during all our waking hours, there is a perpetual con- 
fufed found of various bodies, as of the wind in our rooms, the 
fire, diftant converfations, mechanic bufinefs; this continued 
buzz, as we are feldom quite motionlefs, changes its loudnefs 
perpetually, like the found of a bell; which rifes and falls as 
long as it continues, and feems to pulfate on the ear. This any 
one may experience by turning himfelf round near a waterfall; 
or by ftriking a glafs bell, and then moving the direction of its 
mouth towards the ears, or from them, as long as its vibrations 
continue. Hence this undulation of indiftinct found makes 
another concomitant circle of irritative ideas, which continues 
throughout the day. 
Wc hear this undulating found, when we are perfectly at reft 
ourfelves, from other fonorous bodies befides bells ; as from two 
organ-pipes, which are nearly but not quite in unifon, when they 
are founded together. When a bell is ftruck, the circular form 
is changed into an elliptic one ; the longeft axis of which, as the 
vibrations continue, moves round the periphery of the bell; and 
when either axis of this ellipfe is pointed towards our ears, the 
found is louder; and lefs when the intermediate parts of the 
ellipfe are oppofitc to us. The vibrations of the two organ- 
pipes may be compared to Nonius's rule ; the found is louder, 
when they coincide, and lefs at the intermediate times. But, as 
the found of bells is the moft familiar of thofe founds, which 
have a confiderable battement, the vertiginous patients, who at- 
tend to the irritative circles of founds above dcfcribcd, generally 
compare it to the noife of bells. 
The periftaltic motions of cur ftomach and inteftines, and the 
fecretions Sect. XX. 8. 
OF VERTIGO. 
187 
fecretions of the various glands, are other circles of irritative 
motions, fome of them more or lefs complete, according to our 
abftinence or fatiety. 
So that the irritative ideas of the apparent motions of objects, 
the irritative battements of founds, and the movements of our 
bowels and glands, compofe a great circle of irritative tribes of 
motion : and when one confiderable part of this circle of mo- 
tions becomes interrupted, the whole proceeds in confufion, as 
defcribed in Sedition XVII. i. 7. on Catenation of Motions. 
8. Hence a violent vertigo, from whatever caufe it happens, 
is generally attended with undulating noife in the head, perver- 
fions of the motions of the Itomach and duodenum, unufual ex- 
cretion of bile and gaftric juice, with much pale urine, fome- 
times with yellownefs of the (kin, and a difordered fecretion of 
almoft every gland of the body, till at length the arterial fyftem 
is affected, and fever fucceeds. 
Thus bilious vomitings accompany the vertigo occafioned by 
the motion of a fhip; and when the brain is rendered vertigin- 
ous by a paralytic affection of any part of the body, a vomiting 
generally enfues, and a great difcharge of bile : and hence great 
injuries of the head from external violence are fucceeded by bil- 
ious vomitings, and fometimes by abfcefles of the liver. And 
hence, when a patient is inclined to vomit from other caufes, as 
in fome fevers, any motions of the attendants in his room, or of 
himfelf when he is raifed or turned in his bed, prefently induces 
the vomiting by fuperadding a degree of vertigo. 
9. And converfely it is very ufual v/ith thofe, whofe ftomachs 
are affected from internal caufes, to be afflicted with vertigo, 
and noife in the head ; fuch is the vertigo of drunken people, 
which continues, when their eyes are clofed, and themfelves in a 
recumbent pofture, as well as when they are in an eredl pofture, 
and have their eyes open. And thus the irritation of a ftone in 
the bile-du<T, or in the ureter, or an inflammation of any of the 
inteftines, are accompanied with vomitings and vertigo. 
In thefe cafes the irritative motions of the ftomach, which are 
in general not attended to, become fo changed by fome unnat- 
ural ftimulus, as to become uneafy, and excite our fenfation or 
attention. And thus the other irritative trains of motions, 
which are aflbeiated with it, become difordered by their fympa- 
thy. The fame happens, when a piece of gravel flicks in the 
ureter, or when fome part of the inteftinal canal becomes infla- 
med. In thefe cafes the irritative mufcular motions are firft dif- 
turbed by unufual ftimulus, and a difordered aeftion of the fen- 
fual motions, or dizzinefs enfues. While in fea-ficknefs the dif- 
turbance of the irritative fenfual motions, as vertigo, precedes ; 
and 188 
OF VERTIGO. 
Sect. XX. ie. 
and the difordered irritative mufcular motions, as thofe of the 
ftomach in vomiting, follow. 
io. When thefe irritative motions are difturbed, if the de- 
gree be not very great, the exertion of voluntary attention to 
any other object, or any fudden fenfation, will disjoin thefe new 
habits of motion. Thus fome drunken people have become fo- 
ber immediately, when any accident has ftrongly excited their 
attention ; and fea-ficknefs has vanifhed, when the Chip has been 
in danger. Hence when our attention to other objects is molt 
relaxed, as juft before we fall alleep, or between our reveries 
when awake, thefe irritative ideas of motion and found are moft 
liable to be perceived ; as thofe, who have been at fea, or have 
travelled long in a coach, feem to perceive the vibrations of the 
fhip, or the rattling of the wheels, at thefe intervals; which 
ceafe again, as foon as they exert their attention. That is, at 
thofe intervals they attend to the apparent motions, and to the 
battement of founds of the bodies around them, and for a mo- 
ment miftake them for thofe real motions of the fhip, and noife 
of wheels, which they had lately been accuftomed to : or at thefe 
intervals of reverie, or on the approach of deep, thefe fuppofed 
motions or founds may be produced entirely by imagination. 
We may conclude from this account of vertigo, that fea-fick- 
nefs is not an effort of nature to relieve herfelf, but a neceffary 
confequence of the affociations or catenations of animal motions. 
And may thence infer, that the vomiting, which attends the 
gravel in the ureter, inflammations of the bowels, and the com- 
mencement of fome fevers, has a fimilar origin, and is not al- 
ways an effort of the vis medicatrix naturae. But where the ac- 
tion of the organ is the immediate confequence of the ftimula- 
ting caufe, it is frequently exerted to diflodge that ftimulus, as in 
vomiting up an emetic drug ; at other times, the action of an 
organ is a general effort to relieve pain, as in convulfions of the 
locomotive mufcles ; other actions drink up and carry on the 
fluids, as in abforption and fecretion ; all which may be termed 
efforts of nature to relieve, or to preferve herfelf. 
11. The cure of vertigo will frequently depend on our previ- 
oufly inveftigating the caufe of it, which from what has been 
delivered above may originate from the diforder of any part of 
the great tribes of irritative motions, and of the affociate mo- 
tions catenated with them. 
Many people, when they arrive at fifty or fixty years of age, 
are affected with flight vertigo ; which is generally but wrongly 
afcnbed to indigeftion, but in reality arifes from a beginning de- 
feat of their fight; as about this time they alfo find it neceffary 
to begin to ufe fpedftacles, when they read fmall prints, efpecial- 
■ ■ W \ Sect. XX. 10. 
OF VERTIGO. 
189 
]y in winter, or by candle light, but are yet able to read without 
them during the fummer days, when the light is ftronger. Thefe 
people do not fee objects fo diftinftly as formerly, and by ex- 
erting their eyes more than ufual, they perceive the apparent 
motions of objefts, and confound them with the real motions 
of them ; and therefore cannot accurately balance themfelves lb 
as eafily to preferve their perpendicularity by them. 
That is, the apparent motions of objects, which are at reft, 
as we move by them, fhould only excite irritative ideas: but as 
thefe are now become lefs diftincl, owing to the beginning im- 
perfection of our fight, we are induced voluntarily to attend to 
them ; and then thefe apparent motions become fuccceded by 
fenfation; and thus the other parts of the trains of irritative 
ideas, or irritative mufcular motions, become difordered, as ex- 
plained above. In thefe cafes of flight vertigo I have always 
promifed my patients, that they would get free from it in two 
or three months, as they fhould acquire the habit of balancing 
their bodies by lefs diftinct objects, and have fcldom been mif- 
taken in my prognoftic. 
There is an auditory vertigo, which is called a noife in the 
head, explained in No. 7. of this feCtion, which alfo is very lia- 
ble to affeCt people in the advance of life, and is owing to their 
hearing lefs perfectly than before. This is fometimes called a 
ringing, and fometimes a finging, or buzzing, in the ears, and is 
occafioned by our firft experiencing a difagreeable fenfation from 
our not being able diftinbtly to hear the founds, we ufed former- 
ly to hear diftinCUy. And this difagreeable fenfation excites 
defire and confequent volition ; and when we voluntarily attend 
to fmall indiftimT founds, even the whifpering of the air in a 
room, and the pulfations of the arteries of the ear are fucceeded 
by fenfation ; which minute founds ought only to have produ- 
ced irritative fenfual motions, or unperceived ideas. See Sec- 
tion XVII. 3. 6. Thefe patients after awhile lofe this auditory 
vertigo, by acquiring a new habit of not attending voluntarily 
to thefe indiftinCt founds, but contenting themfelves with the 
lefs accuracy of their fenfe of hearing. 
Another kind of vertigo begins with the difordered aClion of 
fome irritative mufcular motions, as thofe of the ftomach from 
intoxication, or from emetics; or thofe of the ureter, from the 
ftimulus of a ftone lodged in it; and it is probable, that the dif- 
ordered motions of fome of the great congeries of glands, as of 
thofe which form the liver, or of the inteftinal canal, may occa- 
fion vertigo in confequence of their motions being aflbciated or 
catenated with the great circles of irritative motions ; and from 
hence 190 
OF VERTIGO. 
Sect. XX. 12. 
hence it appears, that the means of cure muft be adapted to 
the caufe. 
To prevent fea-ficknefs it is probable, that the habit of fwing- 
ing for a week or two before going on fhip board might be of 
fervice. For the vertigo from failure of fight, fpe&acles may be 
ufed. For the auditory vertigo, aether may be dropt into the ear 
to ftimulate the part, or to diflblve ear-wax, if fuch be a part of 
the caufe. For the vertigo arifing from indigeftion, the peruvi- 
an bark and a blifter are recommended. And for that owing 
to a ftone in the ureter, venefedlion, cathartics, opiates, fal foda 
aerated. 
12. Definition of vertigo. 1. Some of the irritative fenfual, 
or mufcular motions, which were ufually not fucceeded by fen- 
fation, are in this difeafe fucceeded by fenfation ; and the trains 
or circles of motions, which were ufually catenated with them, 
are interrupted, or inverted, or proceed in confufion. 2. The 
fenfitive and voluntary motions continue undifturbed. 3. The 
aflbciate trains or circles of motions continue; but their catena- 
tions with fome of the irritative motions are difordered, or in- 
verted, or dhTevered. 
SECT. Sect. XXL i. 
OF DRUNKENNESS. 
191 
SECT. XXL 
OF DRUNKENNESS. 
I. Sleep from fatiety of hunger. From rocking children. From 
uniform founds. 2. Intoxication from common food after jatigue 
and inanition. 3. From wine or opium. Chiinefs after meals. 
Vertigo. Why pleafure is produced by intoxication, and by fwing- 
ing and rocking children. And why pain is relieved by it. 4. 
Why drunkards Jiagger andJlammer, and are liable to weep. 5. 
And become delirious, feepy and flupid. 6. Or make pale urine 
and vomit. 7. Objects arefeen double. 8. Attention of the mind 
diminijhes drunkennefs. 9. Difordered irritative motions of all 
the fenfes. 1 o. Difeafes from drunkennefs. 11. Definition of 
drunkennefs. 
i. In the ftate of nature when the fenfe of hunger is appeafed 
by the ftimulus of agreeable food, the bufinefs of the day is 
over, and the human favage is at peace with the world, he then 
exerts little attention to external objects, pleafing reveries of im- 
agination fuccecd, and at length fleep is the refult: till the nour- 
ishment which he has procured, is carried over every part of the 
fyftem to repair the injuries of action, and he awakens with 
freih vigour, and feels a renewal of his fenfe of hunger. 
The juices of fome bitter vegetables, as of the poppy and the 
laurocerafus, and the ardent fpirit produced in the fermentation 
of the fugar found in vegetable juices, are fo agreeable to the 
nerves of the ftomach, that, taken in a fmall quantity, they in- 
ftantly pacify the fenfe of hunger ; and the inattention to external 
ftimuli with the reveries of imagination, and fleep, fucceeds, in 
the fame manner as when the ftomach is filled with other lefs 
intoxicating food. 
This inattention to the irritative motions occafioned by ex- 
ternal ftimuli is a very important circumftance in the approach 
of fleep, and is produced in young children by rocking their cra- 
dles : during which all vifible objetls become indiftinfl to them. 
An uniform foft repeated found, as the murmurs of a gentle cur- 
rent, or of bees, are faid to produce the fame effect, by prefenting 
indiftinft ideas of inconfequential founds, and by thus ftealing our 
attention from other objects, whilft by their continued reiterations 
they become familiar themfelves, and we ceafe gradually to at- 
tend to any thing, and fleep enfues. 
2. After great fatigue or inanition, when the ftomach is fud- 
denly filled with flefh and vegetable food, the inattention to ex- 
- ' ternal 192 
OF DRUNKENNESS. 
Sect. XXL 3. 
ternal ftimuli, and the reveries of imagination, become fo confpic- 
ous as to amount to a degree of intoxication. The fame is at any 
time produced by fuperadding a little wine or opium to our com- 
mon meals; or by taking thefe feparately in confiderable quan- 
tity ; and this more efficaciouily after fatigue or inanition; be- 
caufe a lefs quantity of any Simulating material will excite an 
organ into energetic action, after it has lately been torpid from 
defed of ftimulus; as objects appear more luminous, after we 
have been in the dark ; and becaufe the fufpenfion of volition, 
which is the immediate caufe of deep, is fooner induced, after a 
continued voluntary exertion has in part exhaufted the fenforial 
power of volition ; in the fame manner as we cannot contraft 
a fingle mufcle long together without intervals of inaction. 
3. In the beginning of intoxication we are inclined to fleep, 
as mentioned above, but by the excitement of external circum- 
ftances, as of noife, light, bufinefs, or by the exertion of volition, 
we prevent the approaches of it, and continue to take into our 
ftomach greater quantities of the inebriating materials. Bv thefe 
means the irritative movements of the ftomach are excited into 
greater action than is natural ; and in confequence all the irrita- 
tive tribes and trains of motion, which are catenated with them, 
become fufceptible of ftronger adion from their accuftomed 
ftimuli; becaufe thefe motions are excited both by their ufual 
irritation, and by their aflbciation with the increafed actions of 
the ftomach and ladeals. Hence the (kin glows, and the heat 
of the body is increafed, by the more energetic action of the 
whole glandular fyftem ; and pleafure is introduced in confe- 
quence of thefe increafed motions from internal ftimulus. Ac- 
cording to Law 5. Sed. IV. on Animal Caufation. 
From this great increafe of irritative motions from internal 
ftimulus, and the increafed fenfation introduced into the fyftem 
in confequence ; and fecondly, from the increafed fenfitive mo- 
tions in confequence of this additional quantity of fenfation, fo 
much fenforial power is expended, that the voluntary power be- 
comes feebly exerted, and the irritation from the ftimulus of ex- 
ternal objects is lefs forcible; the external parts of the eye are 
not therefore voluntarily adapted to the diftances of objects, 
whence the apparent motions of thofe objects either are feen 
double, or become too indiftind for the purpofe of balancing 
the body, and vertigo is induced. 
Hence we become acquainted with that very curious circum- 
ftance, why the drunken vertigo is attended with an increafe of 
pleafure; for the irritative ideas and motions occafioned by in- 
ternal ftimulus, that were not attended to in our fober hours, 
are now juft fo much increafed as to be fucceeded by plea Curable 
fenfation, Sect. XXL 4. 
OF DRUNKENNESS. 
193 
fcnfation, in the fame manner as the more violent motions of our 
organs are fucceeded by painful fenfation. And hence a greater 
quantity of pleafurable fenfation is introduced into the conftitu- 
tion; which is attended in fome people with an increafe of be- 
nevolence and good humour. 
If the apparent motions of objects is much increafed, as when 
we revolve on one foot, or are fwung on a rope, the ideas of 
thefe apparent motions are alfo attended to, and are fucceeded 
with pleafurable fenfation, till they become familiar to us by fre- 
quent ufe. Hence children are at firft delighted with thefe 
kinds of exercife, and with riding, .and failing, and hence rock- 
ing young children inclines them to fleep. For though in the 
vertigo from intoxication the irritative ideas of the apparent mo- 
tions of objects are indiftinft from their decreafe of energy : yet 
in the vertigo occafioned by rocking or fwinging the irritative 
ideas of the apparent motions of objects are increafed in energy, 
and hence they induce pleafure into the fyftem, but are equally 
indiftimft, and in confequence equally unfit to balance ourielves 
by. This addition of pleafure precludes defire or averfion, and 
in confequence the voluntary power is feebly exerted, and on 
this account rocking young children inclines them to ileep. 
In what manner opium-and wine act in relieving pain is 
another article, that well deferves our attention. There are 
many pains that originate from defeat as well as from excefs of 
ftimulus ; of thefe are thofe of the fix appetites of hunger, thirft, 
luft, the want of heat, of diftention, and of freih air. Thus if 
our cutaneous capillaries ceafe to a£t from the diminilhed ftimu- 
lus of heat, when we are expofed to cold weather, or our ftom- 
ach is uneafy for want of food ; thefe are both pains from defect 
of ftimulus, and in confequence opium, which ftimulates all the 
moving fyftem into increafed action, muft relieve them. But 
this is not the cafe in thofe pains, which arife from excefs of 
ftimulus, as in violent inflammations : in thefe the exhibition of 
opium is frequently injurious by increafing the action of the 
fyftem already too grea't, as in inflammation of the bowels mor- 
tification is often produced by the ftimulus of opium. Where, 
however, no fuch bad confequences follow ; the ftimulus of opi- 
um, by increafing ail the motions of the fyftem, expends fo much 
of the'fenforial power, that the actions of the whole fyftem foon 
become feebler, and in confequence thofe which produced the 
pain and inflammation. 
4. When intoxication proceeds a little further, the quantity 
of pleafurable fenfation is fo far increafed, that all defire cea'es, 
for there is no pain in the fyftem to excite it. Hence the vol- 
untary exertions are diminilhed, ftaggering and Hammering fuc- 
Vol. I. B b ceed ; 194 
OF DRUNKENNESS. 
Sect. XXL 5, 
ceed ; and the trains of ideas become more and more inconfift- 
ent from this defeat of voluntary exertion, as explained in the 
feftions on ileep and reverie, whilft thofe paffions which are un- 
mixed with volition are more vividly felt, and (hewn with lefs 
referve 5 hence pining love, or fuperftitious fear, and the maud- 
ling tear dropped on the remembrance of the moll trifling 
diftrefs. 
5. At length all thefe circumftances are increafed ; the quan- 
tity of pleafure introduced into the fyftem by the increafed irrita- 
tive mufcular motions of the whole fanguiferous, and glandular, 
and abforbent fyftems, becomes fo great, that the organs of fenfe 
are more forcibly excited into adtion by this internal pleafurable 
fenfation, than by the irritation from the ftimulus of external 
objects. Hence the drunkard ceafes to attend to external ftimu- 
li, and as volition is now alfo fufpended, the trains of his ideas 
become totally inconfiftent as in dreams, or delirium : and at 
length a ftupor fucceeds from the great exhauftion of fenforial 
power, which probably does not even admit of dreams, and in 
which, as in apoplexy, no motions continue but thofe from in- 
ternal ftimuli, from fenfation, and from aflbciation. 
6. In other people a paroxyfm of drunkennefs has another ter- 
mination ; the inebriate, as (bon as he begins to be vertiginous, 
makes pale urine in great quantities and very frequently, and at 
length becomes fick, vomits repeatedly, or purges, or has pro- 
fufe fweats, and a temporary fever enfues with a quick ftrong 
pulfe. This in fome hours is fucceeded by deep ; but the un- 
fortunate bacchanalian does not perfectly recover himfelf till 
about the fame time of the fucceeding day, when his courfe of 
inebriation began. As fhewn in Sett. XVII. 1. 7. on Catena- 
tion. The temporary fever with ftrong pulfe is owing to the 
fame caufe as the glow on the Ikin mentioned in the third para- 
graph of this Section : the flow of urine and ficknefs arife from 
the whole fyftem of irritative motions being thrown into confu- 
fion by their aflbeiations with each other ; as in fea-ficknefs, 
mentioned in Se£t. XX. 4- on Vertigo ; and which is more fully 
explained in Seflion XXIX. on Diabetes. 
7. In this vertigo from internal caufes we fee objects double, 
as two candles inftead of one, which is thus explained. Two 
lines drawn through the axes of our two eyes meet at the object 
we attend to : this angle of the optic axes increafes or diminiflies 
with the lefs or greater diflances of objects. All objefts before 
or behind the place where this angle is formed, appear double ; 
as any one may obferve by holding up a pen between his eyes 
and the candle ; when he looks attentively at a fpot on the pen, 
and carelefsly at the candle, it will appear double ; and the re- 
verfe Sect. XXI. 8. 
OF DRUNKENNESS. 
195 
verfe when he looks attentively at the candle and carelefsly at 
the pen; fo that in this cafe the mufcles of the eye, like thofe 
of the limbs, ftagger and are difobedient to the expiring efforts 
of volition. Numerous objects are indeed fometimes feen by 
the inebriate, occafioned by the refractions made by the tears, 
which ftand upon his eye-lids. 
8. This vertigo alfo continues, when the inebriate lies in his 
bed, in the dark, or with his eyes clofed ; and this more power- 
fully than when he is erect, and in the light. For the irrita- 
tive ideas of the apparent motions of objects are now excited by 
irritation from internal ftimulus, or by affociation with other 
irritative motions ; and the inebriate, like one in a dream, be- 
lieves the objects of thefe irritative motions to be prefent, and 
feels himfelf vertiginous. I have obferved in this fituation, fo 
long as my eyes and mind were intent upon a book, the fick- 
nefsand vertigo ceafed, and were renewed again the moment I 
difeontinued this attention ; as was explained in the preceding 
account of fea-ficknefs. Some drunken people have been 
known to become fober inftantly from fome accident, that has 
ftrongly excited their attention, as the pain of a broken bone, or 
the news of their houfe being on fire. 
9. Sometimes the vertigo from internal caufes, as from in- 
toxication, or at the beginning of fomc fevers, becomes fo univer- 
fal, that the irritative motions which belong to other organs of 
fenfe are fucceeded by fenfation or attention, as well as thofe of 
the eye. The vertiginous noife in the ears has been explained 
in SecSt^bn XX. on Vertigo. The tafte of the faliva, which in 
general is not attended to, becomes perceptible, and the patients 
complain of a bad tafte in their mouth. 
The common fmells of the furrounding air fometimes excite 
the attention of thefe patients, and bad fmells are complained of, 
which to other people are imperceptible. The irritative mo- 
tions that belong to the fenfe of preffure, or of touch, are attend- 
ed to, and the patient conceives the bed to librate, and is fear- 
ful of falling out of it. The irritative motions belonging to the 
fenfes of diftention, and of heat, like thofe above mentioned, 
become attended to at this time : hence we feel the pulfation of 
our arteries all over us, and complain of heat, or of cold, in 
parts of the body where there is no accumulation or diminution of 
actual heat. All which are to be explained, as in the laft para- 
graph, by the irritative ideas belonging to the various fenfes be- 
ing now excited by internal ftimuli, or by their afibciations 
with other irritative motions. And that the inebriate, like 
one in a dream, believes the external objects, which ufually 
caufed thefe irritative ideas, to be now prefent. 
10. The 196 
OF DRUNKENNESS. 
Sect. XXL io. 
io. The difeafes in confequence of frequent inebriety, or of 
daily taking much vinous fpirit without inebriety, confift in the 
paralyfis, which is liable to fucceed violent ftimulation. Or- 
gans, whofe actions are aiTociated with others, are frequently 
more affected than the organ, which is ftimulated into too vio- 
lent action. See Se£t. XXIV. 2. 8. Hence in drunken people 
it generally happens, that the fecretory veffels of the liver be- 
come firft paralytic, and a torpor with confequent gall-ftones 
or fcirrhus of this vifcus is induced with concomitant jaundice ; 
otherwife it becomes inflamed in confequence of previous tor- 
por, and this inflammation is frequently transferred to a more 
fenfible part, which is affociated with it, and produces the gout, 
or the rofy eruption of the face, or fome other leprous eruption 
on the head, or arms, or legs. Sometimes the ftomach is firft 
affected, and paralyfis of the lafteal fyftem is induced : whence 
a total abhorrence from flefh-food, and general emaciation. In 
others the lymphatic fyftem is affected with paralyfis, and drop- 
fy is the confequence. In fome inebriates the torpor of the liv- 
er produces pain without apparent fcirrhus, or gall-ftones, or in- 
flammation, or confequent gout, and in thefe epilepfy or infin- 
ity are often the confequence. All which will be more fully 
treated of in the courfe of the work. 
I am well aware, that it is a common opinion, that the gout 
is as frequently owing to gluttony in eating, as to intemperance 
in drinking fermented or fpiritous liquors. To this I anfwer, 
that I have feen no perfon afflicted with the gout, who has not 
drunk freely of fermented liquor, as wine and water, or fmall 
beer; though as the difpofition to all the difeafes, which have orig- 
inated from intoxication,is in fome degree hereditary, a lefs quan- 
tity of fpirituous potation will induce the gout in thefe,-who in- 
herit the difpofition from their parents. To which I mull add, 
that in young people the rheumatifm is frequently miftaken for 
the gout. 
Spice is.feldom taken in fuch quantity as to do any material 
injury to the fyftem, flefli-mcats as well as vegetables are the 
natural diet of mankind ; with thefe a glutton may be crammed 
up to the throat, and fed fat like a ftalled ox ; but he will not 
be difeafed, unlefs he adds fpirituous or fermented liquor to his 
food. This is well known in the diftilleries, where the fwine, 
which are fattened by the fpirituous fediments of barrels, acquire 
difeafed livers. But mark what happens to a man, who drinks 
a quart of wine or of ale, if he has not been habituated to it. 
He lofes tbe ufeof both his limbs and of his underftanding ! He. 
becomes a temporary idiot, and has a temporary ftroke of the 
palfy I And though he flowly recovers after fame hours, is it 
not Sect. XXL 11. 
OF DRUNKENNESS. 
197 
not reafonable to conclude, that a perpetual repetition of <o pow- 
erful a poifon muft at length permanently affeft him ?-If a per- 
fon accidentally becomes intoxicated by eating a few mufhrooms 
of a peculiar kind, a general alarm is excited, and he is faid to 
be poifoned, and emetics are exhibited ; but fo familiarifed are 
we to the intoxication from vinous fpirit, that it occafions laugh- 
ter rather than alarm. 
There is however confiderable danger in too haftily difeontin- 
uing the ufe of fo ftrong a ftimulus, left the torpor of the fyftem, 
or paralyfis, fhould fooner be induced by the omiffion than by 
the continuance of this habit, when unfortunately acquired. A 
golden rule for determining the quantity, which may with fafety 
be difeontinued, is delivered in Scot. XII. 7. 8. 
11. Definition of drunkennefs. Many of the irritative motions 
are much increafed in energy by internal flimulation. 
2. A great additional quantity of pleafurable fenfation is occa- 
fioned by this increafed exertion of the irritative motions. And 
many fenfitive motions are produced in confequence of this in- 
creafed fenfation. 
3. The aflbeiated trains and tribes of motions, catenated with, 
the increafed irritative and fenfitive motions, are difturbed, and 
proceed in confufion. 
4. The faculty of volition is gradually impaired, whence pro- 
ceeds the inftability of locomotion, inaccuracy of perception, and 
inconfiftency of ideas; and is at length totally fufpended, and a 
temporary apoplexy fucceeds. 
SECT. 198 
REPETITION 
Sect. XXII. 1.1. 
SECT. XXII. 
OF PROPENSITY TO MOTION, REPETITION AND IMITATION. 
I. Accumulation offenforial power in hemiplegia, in feep, in cold ft 
of fever, in the locomotive mufcles, in the organs of fenfe. Produ- 
ces propenfity to adtion. II. Repetition by three fenforial powers. 
In rhimes and alliterations, in mufic, dancing, architeclure, land- 
fcape-painting, beauty. III. 1. Perception conf fls in imitation. 
Four kinds of imitation. 2. Voluntary. Dogs taught to dance. 3. 
Senftive. Hencefympathy, and all our virtues. Contagious matter 
of venereal ulcers, of hydrophobia, of jail-fever, offmall-pox, produ- 
ced by imitation, and the fex of the embryon. 4. Irritative imita- 
tion. Imitations refolvable into affociations. 
I. i. In the hemiplegia, when the limbs on one fide have 
loft their power of voluntary motion, the patient is for many 
days perpetually employed in moving thofe of the other. 2. 
When the voluntary power is fufpended during Heep, there com- 
mences a ceafelefs flow of fenfitive motions, or ideas of imagin- 
ation, which compofe our dreams. 3. When in the cold fit of 
an intermittent fever fome parts of the fyftem have for a time 
continued torpid, and have thus expended lefs than their ufual 
expenditure of fenforial power; a hot fit fucceeds, with violent 
action of thofe veffels, which had previoufly been quiefeent. All 
thefe are explained from an accumulation of fenforial power 
during the inactivity of fome part of the fyftem. 
Befides the very great quantity of fenforial power perpetually 
produced and expended in moving the arterial, venous, and glan- 
dular fyftems, with the various organs of digeftion, as defcribed 
in Section XXXII. 3. 2. there is alfo a conftant expenditure of 
it by the aftion of our locomotive mufcles and organs of fenfe. 
Thus the thicknefs of the optic nerves, where they enter the eye, 
and the great expanfion of the nerves of touch beneath the whole 
of the cuticle, evince the great confumption of fenforial power by 
thefe fenfes. And our perpetual mulcular actions in the com- 
mon offices of life, and in conftantly preferring the perpendic- 
ularity of our bodies during the day, evince a confiderable ex- 
penditure of the fpirit of animation by our locomotive mufcles. 
It follows that if the exertion of thefe organs of fenfe and muf- 
cles be for a while intermitted, that fome quantity of fenforial 
power muft be accumulated, and a propenfity to activity of fome 
kind enfue from the increated excitability of the fyftem. Whence 
proceeds Sect. XXII. 2. 1. 
AND IMITATION. 
199 
proceeds the irkfomenefs of a continued attitude, and of an in- 
dolent life. 
However fmall this hourly accumulation of the fpirit of ani- 
mation may be, it produces a propenlity to fome kind of aCtion; 
but it neverthelefs requires either defire or averfion, either pleaf- 
ure or pain, or fome external ftiinulus, or a previous link of af- 
fociation, to excite the fyftem into activity-, thus it frequently 
happens, when the mind and body are fo unemployed as not to 
poflefs any of the three firft kinds of ftimuli, that the laft takes 
place,and confumes the fmall but perpetual accumulation of fen- 
forial. power. Whence fome indolent people repeat the fame 
verfe for hours together, or hum the fame tune. Thus the poet: 
Onward he trudged, not knowing what he fought, 
And whittled as he went, for want of thought. 
IL The repetitions of morions may be at firft produced either 
by volition, or by fen fation, or by irritation, but they foon become 
cafier to perform than any other kinds of action, becaufe they 
foon become affociated together, according to Law the feventh, 
SeClion IV. on Animal Caufation. And becaufe their fre- 
quency of repetition, if as much fenforial power be produced du- 
ring every reiteration as is expended, adds to the facility of 
their production. 
If a Itimulus be repeated at uniform intervals of time, as de- 
fenbed in Se<fl. XII. 3. 3. the aftion, whether of our mufcles or 
organs of fenfe, is produced with ftill greater facility or energy; 
becaufe the fenforial power of aflbeiation, mentioned above, is 
combined with the fenforial power of irritation ; that is, in com- 
mon language, the acquired habit affifts the power of the ftirnulus. 
This not only obtains in the annual, lunar, and diurnal catena- 
tions of animal motions, as explained in Sebt. XXXVI. which 
are thus performed with great facility and energy ; but in every 
lefs circle of actions or ideas, as in the burthen of a long, or the 
reiterations of a dance. To the facility and diftinCtnefs, with 
which we hear founds at repeated intervals, we owe the pleafure, 
which we receive from mulical time, and from poetic time; as 
delcribed in Botanic Garden, P. 2. Interlude 3. And to this 
the pleaiure we receive from the rhimes and alliterations of mod- 
ern verfification ; the fource of which without this key would 
be difficult to difeover. And to this likewife ffiould be afcribed 
the beauty of the duplicature in the perfect tenfe of the Greek, 
verbs, and of fome Latin ones, as tango tetegi, mordeo momordi. 
There is no variety of notes referable to the gamut in the 
beating of the drum, yet if it be performed in mulical time, it is 
agreeable 200 
REPETITION 
Sect, XXII. 2. 1; 
agreeable to our ears ; and therefore this pleafurable fenfation 
muft be owing to the repetition of the divifions of the founds at 
certain intervals of time, or mufical bars. Whether thefe times 
or bars are diftinguiflied by a paufe, or by an emphafis, or accent, 
certain it is, that this diftinftion is perpetually repeated 5 other- 
wife the ear could not determine inftantly, whether the fuccef- 
fions of found were in common or in triple time. In common 
time there is a divifion between every two crotchets, or other 
notes of equivalent time; though the bar in written mufic is put 
after every fourth crotchet, or notes equivalent in time ; in triple 
time the divifion or bar is after every three crotchets or notes equiv- 
alent ; fo that in common time the repetition recurs more fre- 
quently than in triple time. The grave or heroic verfes of the 
Greek and Latin poets are written in common time ; the French 
heroic verfes, and Mr. Anftie's humorous verfes in his Bath 
Guide, are written in the fame time as the Greek and Latin 
verfes, but are one bar ihorter. The Englilh grave or heroic 
verfes are meafured by triple time, as Mr. Pope's tranflation of 
Homer. 
But befides thefe little circles of mufical time, there are the 
greater returning periods, and the (till more diftant chorufles, 
which, like the rhimes at the ends of verfes, owe their beauty 
to repetition ; that is, to the facility and diflinCtnefs with which 
we perceive founds, which we expert to perceive, or have 
perceived before ; or, in the language of this work, to the great- 
er eafe and energy with which our organ is excited by the com- 
bined fenforial powers of affociation and irritation, than by the 
latter fingly. 
A certain uniformity or repetition of parts enters the very com- 
pofition of harmony. Thus two oCtaves neareft to each other 
in the fcale commence their vibrations together after every fec- 
ond vibration of the higher tone. And • where the firft, third, 
and fifth compofe a chord the vibrations concur or coincide fre- 
quently, though lefs fo than in the two octaves. It is probable 
that thefe chords bear fome analogy to a mixture of three alter- 
nate colours in the fun's fpe&rum feparated by a prifm. 
The pleafure we receive from a melodious fuccellion of notes 
referable to the gamut is derived from another fource, viz. to the 
pandiculation or counteraction of antagonift fibres. See Botan- 
ic Garden, P. 2. Interlude 3. If to thefe be added our early af- 
fociations of agreeable ideas with certain proportions of found, 
1 fuppofe, from thefe three fources fpring all the delight of mu- 
fic, fo celebrated by ancient authors, and fo enthufiafticaliy cul- 
tivated at prefent. See SeCt. XVI. No. 10. on InftinCt. 
This kind of pleafure arifing from repetition, that is from the 
facility Sect. XXII. 3. 1. 
AND IMITATION. 
201 
facility and diftin&nefs, with which we perceive and underftand 
repeated fenfations, enters into all the agreeable arts; and when 
it is carried to excefs is termed formality. The art of dancing like 
that of mufic depends for a great part of the pleafure, it affords, 
on repetition; architecture, efpecially the Grecian, confifts of 
one part being a repetition of another ; and hence the beauty of 
the pyramidal outline in landfcape-painting ; where one fide of 
the picture may be faid in fome meafure to balance the other. 
So univerfally does repetition contribute to our pleafure in the 
fine arts, that beauty itfelf has been defined by fome writers to 
confift .in a due combination of uniformity and variety. See 
Sect. XVI. 6. 
III. i. Man is termed by Ariftotle an imitative animal; this 
propenfity to imitation not only appears in the actions of children, 
but in all the cuftoms and faihions of the world : many thou- 
fands tread in the beaten paths of others, for one who traverfes 
regions of his own difcovery. The origin of this propenfity of 
imitation has not, that I recollect, been deduced from any known 
principle ; when any action prefents itfelf to the view of a child, 
as of whetting a knife, or threading a needle, the parts of this ac- 
tion in refpedt of time, motion, figure, are imitated by a part of 
the retina of his eye; to perform this action therefore with his 
hands is eafier to him than to invent any new action, becaufe 
it confifts in repeating with another fet of fibres, viz. with the 
moving mufcles, what he had juft performed by fome parts of 
the retina ; juft as in dancing we transfer the times of motion 
from the actions of the auditory nerves to the mufcles of the limbs. 
Imitation therefore confifts of repetition, which we have ihewn 
above to be the eafieft kind of animal acftion, and which we per- 
petually fall into, when we poflefs an accumulation of fenforial 
power, which is not otherwife called into exertion. 
It has bedn (hewn, that our ideas are configurations of the or- 
gans of fenfe, produced originally in confequence of the ftimu- 
lus of external bodies. And that thefe ideas, or configurations 
of the organs of fenfe, refeinble in fome property a correfpond- 
ent property of external matter; as the parts of the fenfes of 
fight^nd of touch, wdiich are excited into action, refemble in 
figure the figure of the ftimulating body ; and probably alfo the 
colour, ^rd the quantity of denfity, which they perceive. As 
explained i^ Seel. XIV. 2. 2. Hence it appears, that our per- 
ceptions themfelves are copies/*that.is, imitations of fome prop- 
erties of external matter; and the propenfity to imitation is thus 
interwoven with our exiftence, as it is produced by the ftimuli 
©f external bodies, and is afterwards repeated by our volitions 
Vol. I. C c and 202 
REPETITION 
Sect. XXII. 3. 2, 
and fenfations, and thus conftitutes all the operations of our 
minds. 
2. Imitations refolve themfelves into four kinds, voluntary, 
fenfitive, irritative, and aflbciate. The voluntary imitations are, 
when we imitate deliberately the actions of others, either by 
mimicry, as in acting a play, or in delineating a flower; or in 
the common actions of our lives, as in our drefs, cookery, lan- 
guage, manners, and even in our habits of thinking. 
Not only the greateft part of naankind learn all the common 
arts of life by imitating others, but brute animals feem capable 
of acquiring knowledge with greater facility by imitating each 
other, than by any methods by which we can teach them ; as 
dogs and cats, when they are lick, learn of each other to eat 
grafs ; and I fuppofe, that by making an artificial dog perform 
certain tricks, as in dancing on his hinder legs, a living dog 
might be eafily induced to imitate them ; and that the readieft 
way of inftruiling dumb animals is by practifing them with 
others of the fame fpecies, which have already learned the arts 
we wifh to teach them. The important ufe of imitation in ac- 
ouiring natural language is mentioned in Section XVI. 7. and 
8. on InftinCt. 
3. The fenfitive imitations are the immediate confequences 
of pleafure or pain, and thefe are often produced even contrary 
to the efforts of the will. Thus many young men on feeing 
cruel furgical operations become fick, and fome even feel pain 
in the parts of their own bodies, which they fee tortured or 
wounded in others ; that is, they in fome meafure imitate by the 
exertions of their own fibres the violent actions, x^Jaich they 
witnefled in thofe of others. In this cafe a doubfe imitation 
takes place, firft the obl'erver imitates with the extremities of 
the optic nerve the mangled limbs, which are prefent before his 
eyes ; then by a fecond imitation he excites fo violent a&ion of 
the fibres of his own limbs as to produce pain in thofe parts of 
his own body, which he faw wounded in another. In thefe pains 
produced by imitation the effect has fome fimilarity to the caufe, 
which difiinguiihes them from thofe produced by affbeiation ; 
as the pains of the teeth, called tooth-edge, which are produced 
by affbeiation with difagreeable founds, as explained in SeCt. 
XVI. 10. 
The effect of this powerful agent, imitation, in the moral 
world, is mentioned in SeCl. XVI. 7. as it is the foundation of 
all cur intellectual fympathies with the pains and pleafures of 
others, and is in confequence the fource of all our virtues. For 
in what confifts our fympathy with the miferics, or with tire 
joys, of our fellow creatures, but in an involuntary excitation of 
ideas Sect. XXII. 3. 3. 
AND IMITATION. 
203 
ideas in fome meafure fimilar or imitative of thofe, which we 
believe to exift in the minds of the perfons, whom we commit- 
erate or congratulate ? 
There are certain concurrent or fuccelhve aCtions of fome of 
the glands, or other parts of the body, which are poflefled of 
fenftdon, which become intelligible from .this propensity to imi- 
tation. Of thefe are the production of matter by the mem- 
branes of the fauces, or by the fkin, in confequence of the vene- 
real difeafe previoully affeCting the parts of generation. Since 
as no fever is excited, and as neither the blood of fuch patients, 
nor even the matter from ulcers of the throat, or from cutane- 
ous ulcers, will by inoculation produce the venereal difeafe in 
others, as obferved by Mr. Hunter, there is reafou to conclude, 
that no contagious matter is conveyed thither by the blood-vef- 
feis, but that a milder matter is formed by the aCtions of the fine 
v.eflels in thofe membranes imitating each other. See SeCtion 
XXXIII. 2. 9. In this difeafe the actions of thefe veflels pro- 
ducing ulcers on the throat and ficin are imperfeCt imitations of 
thofe producing chancre, or gonorrhoea ; fince the matter produ- 
ced by them is not infe tious, while the imitative aCtions in the 
hydrophobia appear to be perfeCi refemblances, as they produce 
a material equally infeCiious with the original one, which indu- 
ced them. 
The contagion from the bite of a mad dog differs from other 
contagious materials, from its being communicable from other 
animals to mankind, and from many animals to each other ; the 
phenomena attending the hydrophobia are in fome degree expli- 
cable on the foregoing theory. The infeCiious matter does not 
appear to enter the circulation, as it cannot be traced along the 
courfe of the lymphatics from the wound, nor is there any fwell- 
ing of the lymphatic glands, nor does any fever attend, as oc- 
curs in the fmall-pox, and in many other contagious difeafes; yet 
by fome unknown procefs the difeafe is communicated from 
the wound to the throat, and that many months after the injury, 
fo as to produce pain and hydrophobia, with a fecretion of in- 
fectious faliva of the fame kind, as that of the mad dog, which 
infliCted the wound. 
This fubjed is very intricate.-It would appear, that by cer- 
tain morbid aCtions of the falivay glands of the mad dog, a pe- 
culiar kind of faliva is produced ; which being inftilled into a 
wound of another animal ftimulates the cutaneous or mucous 
glands into morbid aCtions, but which are ineffectual in refpeCl 
to the production of a fimilar contagious material; but the fali- 
vary glands by irritative fympathy are thrown into fimilar aCtion, 
ant) 204 
REPETITION 
Sect. XXII. 3.4. 
and produce an infectious faliva fimilar to that inftilled into the 
wound. 
Though in many contagious fevers a material fimilar to that 
which produced the difeafe, is thus generated by imitation ; yet 
there are other infectious materials, which do not thus propagate 
themfelves, but which feem to ad like flow poifons. Of this 
kind was the contagious matter, which produced the jail-fever 
at the aflizes at Oxford about a century ago. Which, though 
fatal to fo many, was not communicated to their nurfes or at- 
tendants. In thefe cafes, the imitations of the fine veffels, as 
above defcribed, appear to be imperfect, and do not therefore pro- 
duce a matter fimilar to that, which ftimulates them j in this 
circumftance refembling the venereal matter in ulcers of the 
throat or fkin, according to the curious difcovery of Mr. Hun- 
ter above related, who found, by repeated inoculations, that it 
would not infect. Hunter on Venereal Difeafe, Part vi. 
ch. i. 
Another example of morbid imitation is in the production of 
a great quantity of contagious matter, as in the inoculated fmall- 
pox, from a fmall quantity of it inferred into the arm. Thefe 
particles of contagious matter ftimulate the extremities of the 
fine arteries of the fkin, and caufe them to imitate the motions 
by which themfelves were produced, and thus to produce a 
thoufand fold of a fimilar material. As different kinds of light 
may be fuppofed to ftimulate parts of the retina into different 
kinds of motion, fo the application of different contagious 
matters may be believed to ftimulate the fine terminations of the 
arteries into different kinds of motion, which may form matters 
fimilar to themfelves. This is truly difficult to underftand, but 
may be conceived to depend on this circumftance ; that thofe 
matters, which ftimulate other bodies into adion, and the bod- 
ies thus ftimulated, mull poffefs fome common properties, as 
fpoken of in Sed. XIV. 4. See Sed. XXXIII. 2. 6. Other 
inftances are mentioned in the Sedion on Generation, which 
fhew the probability, that the extremities of the feminal glands 
may imitate certain ideas of the mind, or actions of the organs 
of fenfe, and thus occafion the male or female fex of the embry- 
pn. See Sed. XXXIX. 6. 
4. We come now to thofe imitations, which are not attended 
with fenfation. Of thefe are all the irritative ideas already ex- 
plained, as when the retina of the eye imitates by its adion or 
configuration the tree or the bench, which I fhun in walking paft 
without attending to them. Other examples of thefe irritative 
imitations are daily obfervable in common life ; thus one yawn- 
ing perfon (hall fet a whole company a yawning j and fome have 
acquired Sect. XXI. 3. 5. 
AND IMITATION. 
205 
acquired winking of the eyes or impediments of fpeech by imita- 
ting their companions without being conl'cious of it. 
5. Bcfides the three fpecies of imitations above defcribed there 
may be fome affociate motions, which may imitate each other in 
the kind as well as in the quantity of their aftion ; but it is 
difficult to diftinguiffi them from the afibciations of motions treat- 
ed of in Section XXXV. Where the actions of other perfons 
are imitated there can be no doubt, or where we imitate a pre- 
conceived idea by exertion of our locomotive mufcles, as in 
painting a dragon; all thefe imitations may aptly be referred to 
the fources above defcribed of the propenfity to abldvity, and the 
facility of repetition ; at the fame time I do not affirm, that all 
thofe other apparent fenfitive and irritative imitations may not be 
refolvable into aflbciations of a peculiar kind, in which certain 
diftant parts of fimilar irritability or fenfibility, and which have 
habitually afted together, may affect each other exactly with the 
fame kinds of motion ; as many parts are known to fympathife 
in the quantity of their motions. And that therefore they may 
be ultimately refolvable into aflbciations of action, as defcribed 
in Sed. XXXV. 
SECT. 206 
PRCULATORY 
Sect. XXIII. i. i. 
SECT. XXIII. 
OF THE CIRCULATORY SYSTEM. 
I. The heart and arteries have no antagonift mufcles. Veins abforb 
the bloody propel it forwards y and diJiend the heart ; contraPlion of 
the heart diJiends the arteries. Vena portarum. IL Glands which 
take their fluids from the blood. With long necks, withJhort necks. 
III. adbforbent fyflem. IV. Heat given out from glandular fe- 
cretions. Blood changes colour in the lungs and in the glands and 
capillaries. V. Blood is abforbed by veins, as chyle by lacteal veflelsy 
other wije they could not join theirJlreamp. VI. Two kinds of flim- 
uluSy agreeable and difagreeable. Glandular appetency. Glands 
originally poflefled fenfation. 
I. i. We now ftep forwards to illuftrate fome of the phenom- 
ena of difeafes, and to trace out their mod efficacious methods 
of cure ; and fhall commence the fubjecl with a Hurt defcrip- 
tion of the circulatory fyftem. 
As the nerves, whofe extremities form our various organs of 
fenfe and mufcles, are all joined, or communicate, by means of 
the brain, for the convenience perhaps of the diltribution of a fub- 
tile ethereal fluid for the purpofe of motion ; fo all thofe veflels 
of the body, which carry the grofler fluids for the purpofes of nu- 
trition, communicate with each other by the heart. 
The heart and arteries are hollow mufcles, and are therefore 
indued with power of contraction in confequence of ftimulus, 
like all other mufcular fibres ; but, as they have no antagonift 
mufcles, the cavities of the veflels, which they form, would re- 
main for eyer clofed, after they have contracted themfelyes, un- 
lefs fome extraneous power be applied to again diftend them. 
This extraneous power in refpeCt to the heart is the current of 
blood which is perpetually abforbed by the veins from the various 
glands and capillaries, and puffied into the heart by a power prob- 
ably very fimilar to that, which raifes the fap in vegetables in 
the fpring, which, according to Dr. Hale's experiment on the 
flump of a vine, exerted a force equal to a column of water 
above twenty feet high. This force of the current of blood in 
the veins is partly produced by their abforbent power, exert- 
ed at the beginning of every fine ramification ; which may be 
conceived to be a mouth abforbing blood, as the mouths of the 
laCleals and lymphatics abforb chyle and lymph. And partly 
by their intermitted compreihon by the pulfations of their gener- 
ally concomitant arteries j by which the blood is perpetually pro- 
pelled Sect. XXIII. 1. 1. 
SYSTEM. 
207 
pelled towards the heart, as the valves in many veins, and the ab- 
forbent mouths in them all, will not fuffer it to return. 
The blood, thus forcibly injeCled into the chambers of the 
heart, diftends this combination of hollow mufcles ; till by the 
ftimulus of detention they contract themfelves; and, puihing 
forwards the blood into the arteries, exert fufficient force to 
overcome in lefs than a fecond of time the vis inertias, and perhaps 
fome elafticity, of the very extenfive ramifications of the two great 
fyftems of the aortal and pulmonary arteries. The power necef- 
fary to do this in fo ihort a time muft be confiderable, and has 
been varioufly eftimated by different phyfiologifts. 
The mufcular coats of the arterial fyftem are then brought into 
aClion by the ftimulus of diftention, and propel the blood to the 
mouths, or through the convolutions, which precede the fecretory 
apertures of the various glands and capillaries. 
In the veffels of the liver there is no intervention of the heart ; 
but the vena portarum, which does the office of an artery, is dif- 
tended by the blood poured into it from the mefenteric veins, and 
is by this diftention ftimulated to contrafl itfelf, and propel the 
blood to the mouths of the numerous glands, which comnofe 
that vifeus. 
The power of abforption in vegetable roots was (hewn by the 
experiments of Dr. Hales on vine-ftumps to be equal to the pref- 
fure of thirty-eight inches of quickfilver. Veg. Staticks, p. 107. 
and from the experiments of Mr. Cooper, who tied the thoracic 
duffs of living dogs, it appeared, that the abforbent power of the 
laiteals and lymphatics always burft the receptaculum chyli. Mr. 
Cooper adds, " The contractile powers of the abforbents are 
proved by thefe experiments to be very ftrong ; for it appears, 
that their a/lion is fufficient to occafion a rupture of their coats. 
It is true, that the receptaculum chyli, which' w'as the part bro- 
ken, is thinner and lefs capable of refiftance than the thoracic 
duct; /et it is able to bear the prefiure of a column of quick- 
filver more than two feet in height. The force therefore exert- 
. ed by the abforbents muft be acknowledged to be greater than 
that of fuch a column of mercury; more efpecially when it is 
remembered, that living parts will refift a force, which will read- 
ily tear them when dead." Medical Refearches. London. 
1798, p. no. 
Dr. Hales made experiments fimilar to thofe on the ftumps 
of vines above mentioned, by opening the crural arteries of a 
horfe, a dog, and a fallow deer, by applying mercurial gauges to 
meafure the projectile impetus of their blood ; and found that of 
the vine-ftump to be five times greater than the force of the 
blood in the great crural artery of a horfe, feven times greater 
than 208 
CIRCULATORY 
Sect. XXIII. 2.1. 
than that of a dog, and eight times greater than that of a fallow 
doe. 
The power of abforption in the animal fydem exerts a force 
fuperior to that of the heart, though perhaps with lefs velocity ; 
and thus removes all difficulty of accounting for the circulation 
in the veins and abforbents ; arvl confequently of the circulation 
in the aortal arteries of fifh, and in the vena portaru m, or the 
bile-fecreting artery of the liver of quadrupeds. 
II. 1. The glandular fyftem of veflels may be divided into thofe, 
which take fome fluid from the circulation ; and thofe, which 
give fomething to it. Thofe, which take their fluid from the cir- 
culation, are the various glands, by which the tears, bile, urine, 
perfpiration, and many other fecretions are produced ; thefe 
glands probably confid of a mouth to felect, a belly to diged, and 
an excretory aperture 60 emit their appropriated fluids; the 
blood is conveyed by the power of the heart and arteries to the 
mouths of thefe glands, it is there taken up by the living power 
of the gland, and carried forwards to its belly, and excretory ap- 
erture, where a part is feparated, and the remainder abforbed 
by the veins for further purpofes. 
Some of thefe glands are furniflied with long convoluted necks 
or tubes, as the feminal ones, which are curioufly feen when 
injected with quickfilver. Others feem to confid of fhorter 
tubes, as that great congeries of glands, which conditute the liver, 
and thofe of the kidneys. Some have their excretory apertures 
opening into refervoirs, as the urinary and gall-bladders. And 
others on the external body, as thofe which fevrete the tears, 
and perfpirable matter. 
Another great fyftem of glands, which have very fhort necks, 
are the capillary veflels ; by which the infenfible perfpiration is 
fecreted on the fkin ; and the mucus of various confidences, 
which lubricates the interdices of the cellular membrane, of the 
mufcular fibres, and of all the larger cavities of the body. From 
the want of a long convolution of veflels fome have doubted, 
whether thefe capillaries (hould be confidered as glands and 
have been led to conclude, that the perfpirable matter rather ex- 
uded than was fecreted. But the fluid of perfpiration is not Am- 
ple water, though that part of it, which exhales into the air may 
be fuch ; for there is another part of it, which in a date of health 
is abforbed again ; but which, when the abforbents are difeafed, 
remains on the furface of the fkin, in the form of feurf, or indu- 
rated mucus. Another thing, which fhews their fimilitude to 
other glands, is their fenfibility to certain affections of the mind ; 
as is feen in the deeper colour of the fkin in the blufh of fhame, 
er the greater palenefs of it from fear. 
IH. Another Sect. XXIII. 3. 
SYSTEM. 
209 
III. Another feries of glandular veflels is called the abforbent 
fyftem ; thefe open their mouths into ail the cavities, and upon 
all thofe furfaces of the body, where the excretory apertures of 
the other glands pour out their fluids. The mouths of the ab- 
forbent fyftem drink up a part or the whole of thefe fluids, and 
carry them forwards by their living power to their refpedive 
glands, which are called conglobate glands. There thefe fluids 
undergo feme change, before they pafs on into the circulation ; 
but if they are very acrid, the conglobate gland fwells, and fome- 
times fuppurates, as in inoculation of the fmall-pox, in the plague, 
and in venereal abforptions ; at other times the fluid may per- 
haps continue there, till it undergoes fome chemical change, that 
renders it-lefs noxious; or, what is more likely, till it is regurgi- 
tated by the retrograde motion of the gland in fpontaneous fweats 
or diarrhoeas, as difagreeing food is vomited from the flomach. 
The powers of abforption are fhewn in No. I. of this Section, 
both thofe of the blood and of the chyle of animals, and of the 
fap-juice of vegetables, to be much greater than has commonly 
been conceived. To which may be added, that the moving 
force of the chyle in the receptaculum chyli and thoracic dufl 
mull be equal to the moving force of the blood in the fubclavian 
vein, as otherwife the chyle could not enter into that vein, un- 
lefs it be fuppofed to poflefs a fyftole and diaflole near the heart; 
which alfo affords an argument to (hew, that the progrefs of the 
blood in the veins, and that of the chyle in the abforbent fyflem, 
originates from a fimilar caufe, that of their abforptive powers. 
IV. As all the fluids, that pafs through thefe glands, and ca. 
pillary veifels, undergo a chemical change, acquiring new com- 
binations, the matter of heat is at the fame time given out; this 
is apparent, fince whatever increafes mfenfible perfpiration, in- 
creafes the heat of the fkin ; and when the action of thefe veflels 
is much increafed but for a moment, as in blufhing, a vivid heat 
on the fkin is the immediate confequence. So when great bil- 
ious fecretions, or thofe of any other gland, are produced, heat 
is generated in the part in proportion to the quantity of the fe- 
cretion. 
The heat produced on the fkin by blufhing may be thought 
by fome too hidden to be pronounced a chemical etF^cl, as the 
fermentations or new combinations taking place in a fluid is in 
general a flower procefs. Yet are there many chemical mixtures 
in which heat is given out as inflantaneoufly ; as in folutions of 
metals in acids, or in mixtures of effential oils and acids, as of 
oil ofcloves and acid of nitre. So the bruifed parts of an un- 
ripe apple become almoft inflantaneoufly fweet ; and if the chem- 
ico-animal procefe of digeftion be flopped for but a moment, as 
Vol. I. Do by 210 
CIRCULATORY 
Sect. XXIII. 
by fear, or even by voluntary eructation, a great quantity of air 
is generated, by the fermentation, which inftantly fucceeds the 
Hop of digeftion. By the experiments of Dr. Hales it appears, 
that an apple during fermentation gave up above fix hundred 
times its bulk of air ; and the materials in the ftomach are fuch, 
and in fuch a fituation, as immediately to run into fermentation, 
when digeftion is impeded. 
As the blood pafles through the fmall veflels of the lungs, 
which connect the pulmonary artery and vein, it undergoes a 
change of colour from a dark to a light red ; which may be term- 
ed a chemical change, as it is known to be eftetted by an ad- 
mixture of oxygene, or vital air ; which, according to a difcov- 
ery of Dr. Prieftley, pafles through the moift membranes, which 
Conftitute the fades of thefe veflels. As the blood pafles through 
the capillary veflels, and glands, which connect the aorta and 
its various branches with their correfponderit veins in the ex- 
tremities of the body, it again lofes the bright red colour, and 
■(Undergoes feme new combinations in the glands cr capillaries, 
in which the matter of heat is given out from the fecreted fluids. 
This procefs therefore, as well as the procefs of refpiration, has 
fome analogy to combuftion, as the vital air or' oxygene feenis 
to become united to fome inflammable bafe, and the matter 
of heat efcapes from the new acid, which is thus produced. 
V. After the blood has pafled thefe glands and capillaries, 
and parted with whatever they chofe to take from it, the re- 
mainder is received by the veins, which are a fet of blood-abforb- 
ing veflels in general correfponding with the ramifications of the 
arterial fyftem. At the extremity of the fine convolutions of the 
glands the arterial force ceafes; this in refpefl to the capillary 
veflels, which unite the extremities of the arteries with the com- 
mencement of the veins, is evident to the eye, on viewing the 
tail of a tadpole by means of a folar, or even by a common mi- 
erofcope, for globules of blood are feen to endeavour to pafs, and 
to return again and again, before they become abforbed by the 
mouths of ihe veins ; which returning of thefe globules evinces, 
that the arterial force behind them has ceafed. The veins are 
furnifhed with valves like the lymphatic abforbents ; and the 
great trunks of the veins, and of the la&eals and lymphatics, 
join together before the ingrefsof their fluids into the left cham- 
ber of the heart; both which evince, that the blood in the veins, 
and the lymph and chyle in the latleals and lymphatics, are car- 
ried on by a fimilar force ; otherwife the ftream, which was pro- 
pelled with a lefs power, could not enter the veflels, which con- 
tained the ftream propelled with a greater power. From whence 
it appears, that the veins are a fyftem of veflels abforbing blood, 
as Sect. XXIIL 6. 
-SYSTEM. 
211 
as the la&eals and lymphatics are a fyftem of veflels abforbing 
chyle and lymph. See Se<ft. XXVII. i. 
VI. The movements of their adapted fluids in the various 
veflels of t;he bedy are carried forwards by the actions of thofe 
veflels in confequence of two kinds of ftimulus, one of which may 
be compared to apleafurable fenfation or deflre inducing the vef- 
fel to feize, and, as it were, to fwallow the particles thus felecl- 
ed from the blood ; as is done by the mouths of the various 
glands, veins, and other abforbents, which may be called glandu- 
lar appetency. The other kind of ftimulus may be compared, 
to difagreeable fenfation, or averfion, as when the heart has re- 
ceived the blood, and is ftimulated by it to pufh it forwards into 
the arteries ; the fame again ftimulates the arteries to contract, 
and carry forwards the blood to their extremities, the glands 
^nd capillaries. Thus the mefenteric veins abforb the blood 
from the inteftines by glandular appetency, and carry it for- 
ward to the vena portarum ; which afling as an artery con- 
trails itfelf by difagreeable ftimulus, and puihes it to its ramified 
extremities, the various glands, which conftitute the liver. 
It feems probable, that at the beginning of the formation of 
thefe veflels in the embryon, an agreeable fenfation was in real- 
ity felt by the glands during fecretion, as is now felt in the act 
of fwallowing palatable food; and that a difagreeable fenfation 
was originally felt by the heart from the diftention occafioned 
by the blood, or by its chemical ftimulus ; but that by habit 
thefe are all become irritative motions ; that is, fuch motions 
as do not affeil the whole fyftem, except when the veflels are 
4ifeafed by inflammation. 212 
OF THE SALIVA 
Sect. XXIV. i. 
SECT. XXIV. 
OF THE SECRETIONS OF SALIVA, AND OF TEARS, AND OF THE 
LACRYMAL SACK. 
I. Secretion of faliva increafed by mercury in the blood. I. By the 
food in the mouth. Drynefs of the mouth not from a deficiency of 
faliva. 2. By fenfative ideas. 3. By volition. 4. By difiafie- 
ful fubfiances. It is fecreted in a dilute and faline date. It then 
becomes more vifeid. C. By ideas of dijlafieful fubfiances. 6. 
By naufea. 7. By averfion. 8. By catenation with fiimulating 
fubfiances in the ear. II. 1. Secretion of tears lefs in fieep. 
From Jlimulation of their excretory duel. 2. Lacrymal fack is a 
gland. 3. Its ufes. 4. Tears are fecreted, when the nafal dull 
is flimulated. 5. Or when it is excited by fenfation. 6. Or by 
volition. 7. The lacrymalfack can regurgitate its contents into 
the eye. 8. Flore tears are fecreted by aflbeiation with the irri- 
tation of the nafal duct of the lacrymal fack, than the panel a lacry- 
malia can imbibe. Of the gout in the liver and fiomach. 
I. The falival glands drink up a certain fluid from the cir- 
cumfluent blood, and pour it into the mouth. They are fome- 
times flimulated into action by the blood, that furrounds their 
origin, or by fome part of that heterogeneous fluid : for when 
mercurial faits, or oxydes, are mixed with the blood, they ftim- 
ulate thefe glands into unnatural exertions; and then an u ufual 
quantity of faliva is Separated. 
i. As the faliva fecreted by thefe glands is moft wanted during 
the maftication of our food, it happens, when the terminations 
of their duels in the mouth are ftimulated into action, the fali- 
val glands themfelves are brought into increafed action at the 
fame time by aflbciation, andfeparate a greater quantity of their 
juices from the blood ; in the fame manner as tears are produ- 
ced in greater abundance during the ftimulus of the vapour of 
onions, or of any other acrid material in the eye. 
The faliva is thus naturally poured into the mouth only du- 
ring the ftimulus of our iood in maftication ; for when there is 
too great an exhalation of the mucilaginous fecretion from the 
membranes, which line the mouth, or too great an abforption of 
it, the mouth becomes dry, though there is no deficiency in the 
quantity of faliva ; as in thofe who fleep with their mouths 
open, and in fome fevers. 
2. Though during the maftication of otir natural food the fa- 
lival glands are excited into ailion by the ftimulus on their ex- 
cretory Sect. XXIV. 1.3. 
AND TEARS. 
213 
crctory ducts, and a due quantity of faliva is feparated from the 
blood, and poured into the mouth ; yet as this maftication of our 
food is always attended with a degree of pleafure; and that 
pleafurable fenfation is alfo connected with our ideas of certain 
kinds of aliment; it follows, that *when thefe ideas arc repro- 
duced, the pleafurable fenfation arifes along with them, and the 
falival glands are excited into action, and nil the mouth with fa- 
liva from this fenfitive aflbeiation, as is frequently feen in dogs, 
who Haver at the light of food. 
3. We have alfo a voluntary power over the action of thefe 
falival glands, for we can at any time produce a flow of faliva 
into our mouth, and fpit out, or fwallow it at will. 
4. If any very acrid material be held in the mouth, as the 
root of pyrethrum, or the leaves of tobacco, the falival glands are 
ftimulated into itrongcr action than is natural, and thence fe- 
crete a much larger .quantity of faliva ; which is at the fame 
time more vifeid than in its natural ftate; becaufe the lymphat- 
ics, that open their mouths into the dufts of the falival glands, 
and on the membranes, which line the mouth, are likewife llim- 
ulated into ftronger action, and abforb the more liquid parts of 
the faliva with greater avidity ; and the remainder is left both in 
greater quantity and more vifeid. 
The increafed abforption in the mouth by fome ftimulating 
fubftances, which are called aftringents, as crab-juice, is evident 
from the inftant drynefs produced in the mouth by a finall 
quantity of them. 
As the extremities of the glands are of exquifite tenuity, a? 
appears by their difficulty of injection, it was neceflary for them 
to fecrete their fluids in a very dilute ftate ; and, probably for the 
purpofe of ftimulating them into adtion, a quantity of neutral 
fait is likewife fecreted or formed by the gland. This aqueous 
and falitie part of all fecreted fluids is again reabforbed into the 
habit. More than half of fome fecreted fluids is thus imbibed 
from the refervoirs, into which they are poured; as in the urin- 
ary bladder much more than half of what is fecreted by the kid- 
neys becomes reabforbed by the lymphatics, which are thickly 
difperfed around the neck of the bladder. This feems to be the 
purpofe of the urinary bladders of fifh, as otherwife fuch a re- 
ceptacle for the urine could have been of no ufc to an animal 
immerfed in water. 
5. The idea of fubftances difagreeably acrid will alfo produce 
a quantity of faliva in the mouth; as when we fmellvery putrid 
vapours, we are induced to fpit out our faliva, as if fomething 
difagreeable was actually upon our palates. 
6. When difagreeable food in the ftomach produces naufea, 
t ' a 214 
OF THE SALIVA 
Sect. XXIV. r. 7 
.a flow of faliva is excited in the mouth by aflbciation ; as efforts 
to vomit are frequently produced by disagreeable drugs in the 
mouth by the fame kind of affociation. 
7. A preternatural flow of faliva is likewife femetimes occa- 
sioned by a difeafe of the voluntary power ; for if we think about 
cur faliva, and determine net to fwallow it, or not to fpit it out, 
an exertion is produced by the will, and more faliva is fecreted 
againft our wilh ; that is, by our averlion, which bears the fame 
analogy to defire, as pain does to pleafure ; as they are only 
modifications of the fame difpofition Qi the fenforium. Sec 
Clafs IV. 3. 2. 1. 
8- The quantity of faliva may alfo be increafed beyond what 
is natural, by the catenation of the motions of lhefe glands with 
other motions, or fenfations, as by an extraneous body in the 
ear ; of which I have known an inftance ; or by the application 
cf ftizolobium, fiiiqua hirfuta, cowhage, to the feat of the paro-» 
tis, as feme writers have affirmed. 
II. 1. The lacrymal gland drinks up a certain fluid from the 
circumfluent blood, and pours it on the ball of the eye, on the 
upper part of the external corner of the eyelids. Though it may 
perhaps be ftimujated into the performance of its natural aftion 
by the blood, which furrounds its origin, or by fome part of that 
heterogeneous fluid ; yet as the tears fecreted by this gland are 
more wanted at fome times than at others, its fecretion is varia- 
ble, like that of the faliva above mentioned, and is chiefly pro- 
duced when its excretory duct is ftimulated ; for in our common 
fbep there feems to be little or no fecretion of tears ; though 
they are occafionally produced by our fenfations in dreams. 
Thus when any extraneous material on the eye-ball, or the 
dj-ynefs of the external covering of it, or the coldnefs of the air, 
or the acrimony of fome vapours, as of onions, ftimulates the 
excretory dudi of the lacrymal gland, it difeharges its contents 
upon the ball; a quicker fecretion take§ place in the gland, and 
abundant tears fucceed, to moiften, clean, and lubricate the eye. 
Thefe by frequent nictitation are diffufed over the whole ball, 
and as the external angle of the eye in winking is clofed fooner 
than the internal angle, the tears are gradually driven forwards, 
apd downwards from the lacrymal gland to the pundta lacryma- 
lia. 
2. The lacrymal fack, with its punfta lacrymalia, and its nafal 
duct, is a complete gland ; and is Angular in this refpeft, that it 
neither derives its fluid from, nor dilgorges it into the circulation. 
The fimplicity of the ftrudlure of this gland, and both the ex- 
tremities of it being on the furfacc of the body, makes it well 
worthy our minuter obfervation ; as the actions of more intricate 
and 8sct. XXIV. 2. 3. 
AND TEARS. 
215 
and concealed glands may be better underftood from their anal- 
ogy to this. 
3. This Ample gland confifts of two abforbing mouth's, abel- 
ly, and an excretory duff. As the tears are brought to the in- 
ternal angle of the eye, thefe two mouths drink them up, being 
ftimulated into adtion by this fluid, which they abforb. The 
belly of the gland, or lacrymal fack, is-thus filled, in which the 
faline part of the tears is abforbed, and when the other end of 
the gland, or nafal duel, is ftimulated by the drynefs, or pained 
by the ccldnefs of the air, or afleHed by any acrimoneous duft 
or vapour in the noftrils, it is excited into aition together with 
the fack, and the tears are difgorged upon the membrane, which 
lines the noftrils; where they ferve a fecond ptirpofe to moiften, 
clean, and lubricate, the organ of fmell. 
4. This gland, when its nafal dudt is ftimulated by any very 
acrid material, as the pow er of tobacco, or volatile fpirits, not on- 
ly difgorgesthe contents of its belly or receptacle (the lacrymal 
fack), and abforbs haftily all the fluid, that is ready for it in the 
Corner of the eye; but by the aflbeiation of its motions with 
thofe of the lacrymal gland, excites that alfo into increafed ac- 
tion, and a large flow of tears is poured into the eye. 
5. This nafal ducSl is like wife excited into ftrong a£Kon by 
fenfitive ideas, as in grief, or joy, and then alfo by its aflbeiations 
with the lacrymal gland it produces a great flow of tears with- 
out any external ftimulus ; as is more fully explained in Seel. 
XVI. 8. on InftincT. 
6. There are fome, famous in the arts of exciting companion, 
who are faid to have acquired a voluntary power of producing a. 
flow of tears in the eye ; which, from what has been faid in the 
febtion on InftinCt above mentioned, I fliould fufpecl, is perform- 
ed by acquiring a voluntary power over the action of this nafal 
duff. 
7. There is another circumftance well worthy our attention, 
that when by any accident this nafal dutft is obftrudted, the lac- 
rymal fack, which is the belly or receptacle of this gland, by 
flight preffurc of the finger rs enabled to difgorge its contents 
again into the eye ; perhaps the bile in the fame manner, when 
the biliary duds are obftruded, is returned into the blood by 
the veflels which fecrete it ? 
8. A very important though minute occurrence muft here be 
obferved, that though the lacrymal gland is only excited into ac- 
tion, when we weep at a diftrefsful tale, by its aflbeiation with 
this nafal du<ft,as is more fully explained in Sedf. XVI. 8 ; yet the 
quantity of tears fecreted at once is more than the purnfta lacry- 
malia can readily abforb ; which (hews that the imtmu accafwned 
by 216 
OF THE SALIVA, &c. Sect. XXIV. 2. S. 
by afpciations are frequently more energetic than the original motionst 
by which they were occaftoneiL Which we fhall have Gccafion to 
mention hereafter, to illuftrate, why pains frequently exift in a 
parr dillant from the caufe of them, as in the other end of the 
urethra, when a ftone ftimulates the neck of the bladder. And 
why inflammations frequently arife in parts diftant from their 
caufe, as the gutta rofea of drinking people, from an inflamed 
liver. 
The inflammation of a part is generally preceded by a torpor 
or quiefcence of it; if this exifts in any larger congeries of glands, 
as in the liver, or any membranous part, as the ftomach, pain 
is produced and chillinefs in confequence of the torpor of the 
vefl'els. In this fituation fometimes an inflammation of the parts 
fucceeds the torpor; at other times a diftant more fenfible part be-* 
comes inflamed ; whofe actions have previoufly been aflociated 
with it: and the torpor of the firlt part ceafes. This I appre- 
hend happens, when the gout of the foot fucceeds a pain of the 
biliary dudt, or of the ftomach. Laftly, it fometimes happens, 
that the pain of torpor exifts without any confcquent inflamma- 
tion of the affedted part, or of any diftant part aflociated with it, 
as in the membranes about the temple and eye-brows in hemi- 
crania, and in thofe pains, which occafion convulfions; if this 
happens to gouty people, when it affects the liver, I fuppofe epi- 
leptic fits are produced ; and, when it affects the ftomach, death 
is the confequence. In thefe cafes the pulfe is weak, and the 
extremities cold, and fuch medicines as ftimulate the quiefcent 
parts into action, or which induce inflammation in them, or in 
any diftant part, which is aflociated with them, cures the pref- 
ent pain of torpor, and faves the patient. 
I have twice feen a gouty inflammation of the liver, attended 
with jaundice ; the patients after a few days were both of them 
affefted with cold fits, like ague fits, and their feet -became af- 
fected with gout, and the inflammation of their livers ceafed. 
It is probable, that the uneafy fenfations about the ftomach, and 
indigeftion, which precedes gouty paroxyfms, are generally ow- 
ing to torpor or flight inflammation of the liver, and biliary 
dutfts ; but where great pain with continued ficknefs, with feeble 
pulfe, and fenfation of cold, affeCl the ftomach in patients debil- 
itated by the gout, that it is a torpor of the ftomach itfelf, and 
deftroys the patient from the great connexion of that vifeus with 
the vital organs. See Sett. XXV. 17. 
SECT. Sect. XXV. i. 
OF THE STOMACH, &c. 
217 
SECT. XXV. 
OF THE STOMACH AND INTESTINES. 
t. Of fwallowing our food. Ruminating animals. 2. A flion of 
the ftomach. 3. Action of the inteftincs. Irritative motions con- 
nected with thefe. 4. Effects of repletion. 5. Strenger a flion 
of the ftomach and inteftines from more ftimulating food. 6. 
Eheir action inverted by ftill greater ftimuli. Or by dfgffful 
ideas. Or by volition. 7. Other glands ftrengthen or invert 
their motions by Jympathy. 8. Vomiting performed by intervals, 
cy. Inverfton of the cutaneous abforbents. 10. Increafed fecretion 
of bile and pancreatic juice, it. Inverfton of the la fleals. 12. 
And of the bile-ducts. 13. Cafe of a cholera. 14. Farther ac- 
count of the inverfton of la fleals. 15 Iliac pftfion. Valve of 
the colon. 16. Cure of the iliac paftlon. 17. Pain of gall- 
flone diftinguijhed from pain of the ftomach. Gout of the ftomach 
from torpor^ from inflammation. Intermitting pufe owing to in- 
digeflion. Io overdofe of foxglove. IVeak pulfe from emetics. 
Death from a blow on theftomach. From gout of theftomach. 
i; The throat, ftomach, and inteftines, may be confidered as 
one great gland ; which like the lacrymal fack above mentioned, 
neither begins nor ends in the circulation. Though the adl of 
mafticating our aliment belongs to the fenfitive clafs of motions, 
for the pleafure of its tafte induces the inufcles of the jaw into 
action ; yet the deglutition of it when mafticated is generally, 
if not always, an irritative motion, occafioned by the application 
of the food already mafticated to the origin of the pharinx; in 
[ the'fame manner as we often fwallow our fpittle without attend- 
ing to it. * t • ' < 
The ruminating clafs of animals have the power to invert th^ 
motion of their gullet, and of their firft ftomach, from the ftim- 
ulus of this aliment, when it is a little further prepared ; as is 
their daily piatlice in chewing the cud; and appears to the eye 
of any one, who attends to them, whilft they are employed in 
this fecond maftication of their food. 
2. When our natural aliment arrives into the ftomach, this or- 
gan is ftimulated into its proper vermicular adlion ; which be- 
ginning at the upper orifice of it, and terminating at the lower 
one, gradually mixes together and pufhes forwards the digefting 
materials into the inteftine beneath it. 
At the fame time the glands, that fupply the gaftric juices, 
which are neceflary to promote the chemical part of the procefs 
Vol. I. I*e of 218 
OF THE STOMACH 
Sect. XXV. > 
of digeftion, arc Simulated to difeharge their contained fluids, 
and to feparate a further fupply from the blood-veflels : and the 
llcfeals or lymphatics, which open their mouths into the ftomach, 
are ftimulated into action, and take up fome part of the digetting 
materials. 
3. The remainder of thefe digefting materials is carried for- 
wards into the upper inteftines, and flimulates them into their 
periftaltic motion fimilar to that of the itomach ; which contin- 
ues gradually to mix the changing materials, and pafs them along 
through the valve of the colon to the excretory end of this great 
gland, the fphindler ani. 
The digefting materials produce a flow of bile, and of pancre- 
atic juice, as they pafs along the duodenum, by ftimulating the 
excretory dudts of the liver and pancreas, which terminate in 
that inteftine : and other branches of the abfoibent or lymphatic 
fyftem, called la&eals, are excited to drink up, as it pafles, thofe 
parts of the digefting materials, that are proper for their purpofe, 
by its ftimulus on their mouths. 
4.|When the ftomach and inteftines are thus filled with their 
proper food, not only the motions of the gaftric glands, the pan- 
creas, liver, and lacteal veflels, are excited into a&ion; but at 
the fame time the whole tribe of irritative motions are exerted 
with greater energy, a greater degree of warmth, colour, plump- 
nefs, and moifture, is given to the fkin from the increafed adtiort 
of thofe glands called capillary veflels; pleafurable fenfation is 
excited, the voluntary motions are lefs eafily exerted, and at 
length fufpended ; and fleep fucceeds, unlefs it be prevented by 
the ftimulus of furrounding objects, or by voluntary exertion, or 
by an acquired habit, which was originally produced by one or 
other of thefe cifcumftanCes, as is explained in Sedt. XXI. on 
Drunkennefs. 
At this time alfo, as the blood-veflels become replete with 
chyle, more urine is feparated into the bladder, and lefs of it is^ 
reabforbed; more mucus poured into the cellular membranes', 
and lefs of it reabforbed : the pulfe becomes fuller, and fofter, 
and in general quicker. The reafon why lefs urine and cellular 
mucus is abforbed after a full meal with fufficient drink is owing 
to the blood-veflels being fuller : hence one means to promote ab- 
forption is'to decreafe the refiftance by emptying the veflels by 
venefedlion. From this decreafed abforption the urine becomes 
pale as- well as copious, and the fkin appears plump as well as 
florid. 
By daily repetition qf thefe movements they all become edn-t 
nested together, and make a diurnal circle of irritative adiion, 
and Sect, XXV. 5. 
AND INTESTINES. 
219 
and if one of this chain be difturbed, the whole is liable to be 
put into diforder. See Sect. XX. on Vertigo. 
5. When the ftomach and inteftines receive a quantity of food, 
whofe ftimulus is greater than ufual, all their motions, and thofe 
of the glands and lymphatics, are ftimulated into ftronger action 
than ufual, and perform their offices with greater vigour and in 
lefs time : fuch are the effects of certain quantities of fpice or of 
vinous fpirit. 
6. But if the quantity or duration of thefe ftimuli are ftill 
further increafed, the ftomach and throat are ftimulated into a 
motion, whofe direction is contrary to the natural one above de- 
fcribed ; and they regurgitate the materials, which they contain, 
inftead of carrying them forwards. This retrograde motion of the 
ftomach may be compared to the ftretchings of wearied limbs the 
contrary way, and is well elucidated by the following experiment. 
Look earneftly for a minute or two on an area an inch fquare of 
pink filk, placed in a Itrong light, the eye becomes fatigued, the 
colour becomes faint, and at length vaniihes, for the fatigued 
eye can no longer be ftimulated into direct motions ; then on 
clofing the eye a green fpeftrum will appear in it, which is a 
colour direftly contrary to pink, and which will appear and dif- 
appear repeatedly, like the efforts in vomiting. See Section 
XXIX. II. 
Hence all thofe drugs, which by their bitter cr aftringent ftim- 
ulus increafe the action of the ftomach, as camomile and white 
vitriol, if their quantity is increafed above a certain dofe become 
emet'cs. 
Thefe inverted motions of the ftomach and throat are gener- 
ally produced from the ftimulus of unnatural food,and are attend- 
ed with the fenfation of naufea or ficknefs : but as this fenfation 
is again connected with an idea of the diftafteful food, which 
induced it; fo an idea of naufeous food will alfo fometimes ex- 
cite the action of naufea ; and that give rife by affociation to the 
inverfion of the motions of the ftomach and throat. As fome, 
whohavehad horfe-flefh or dogs-flefh given them for beef or mut- 
ton, are faid to have vomited many hours afterwards, when they 
have been told of the impofition. 
I have been told of a perfon, who had gained a voluntary com- 
mand over thefe inverted motions of the ftomach and throat, and 
fupported himfelf by exhibiting this curiofity to the public. At 
thefe exhibitions he fwallowed a pint of red rough goofeberries, 
and a pint of white fmooth ones, brought them up in fmall par- 
cels into his mouth, and reftored them feparately to the fpe£ta- 
tors, who called for red or white as they pleafed, till the whole 
were redelivered. 
' ► 7. At 220 
OF THE STOMACH 
Sect. XXV. 7. 
At the fame time that thefe motions of the ftomach and 
throat are ftimulated into inverfion, fome of the other irritative 
motions, that had acquired more immediate connexions with the 
ftomach, as thofe of the gaftric glands, are excited into ftronger 
adlion by this aflociation; and fome other of thefe motions, 
which are more eafily excited, as thofe of the gaftric lymphatics, 
are inverted by their aflociation with the retrograde motions of 
the ftomach, and regurgitate their contents, and thus a greater 
quantity of mucus, and of lymph, or chyle, is poured into the 
ftomach, and thrown up along with its contents. 
8. Thefe inverfipns of the motion of the ftomach in vomiting 
are performed by intervals, for the fame reafon that many other 
motions are reciprocally exerted and relaxed ; for during the 
time of exertion the ftimulus, or fenfation, which caufed this ex- 
ertion, is not perceived ; but begins to be perceived again, as 
loon as the exertion ceafes, and is fome time in again producing 
its effect. As explained in Se<St. XXXIV. on Volition, where 
it is (hewn, that the contia&ions of the fibres, and the fenfation 
of pain, which occafioned that exertion, cannot exift at the fame 
time. The exertion ceafes from another caufe alfo, which is the 
exhauftion of the fcnforial power of the part, and thefe two caufes 
frequently operate together. 
9. At the times of thefe inverted efforts of the ftomach not on- 
ly the lymphatics, which open their mouths into the ftomach, 
but thofe of the fkin alfo, are for a time inverted : for fweats are 
fometimes puflied out during the efforts of vomiting without an 
increafe of heat. 
10. But if by a greater ftimulus the motions of the ftomach 
are inverted ftill more violently or more permanently, the duod- 
enum has its periftaltic motions inverted at the fame time by 
their aflociation with thofe of the ftomach ; and the bile and pan- 
creatic juice, which it contains, are by the inverted motions 
brought up into the ftomach, and difeharged along with its con- 
tents ; while a great quantity of bile and pancreatic juice is pour- 
ed into this inteftine ; as the glands, that fecrete them, are by 
their aflociation with the motions of the inteftine excited into 
ftronger action than ufual. 
11. The other inteftines are by aflociation excited into more 
powerful action, while the lymphatics, that open their mouths 
into them, fuffer an inverfion of their motions correfponding with 
the lymphatics of the ftomach, and duodenum; which with a 
part of the abundant fecretion of bile is carried downwards, and 
contributes both to ftimulate the bowels, and to increafe the quan- 
tity of the evacuations. This inverfion of the motion of the lym- 
phatics appears from the quantity of chyle, which comes away 
by Sect. XXV. 12. 
AND INTESTINES. 
221 
by ftools ; which is otherwife abforbed as foon as produced, 
and by the immenfe quantity of thin fluid, which is evacuated 
along with it. * 
12. But if the ftimulus, which inverts the ftomach, be ftill 
more powerful, or more permanent, it fometirnes happens, that 
the motions of the biliary glands, and of their excretory dudts, 
are at the fame time inverted, and regurgitate their contained 
bile into the blood-vefl'els, as appears by the yellow colour of the 
fkin, and of the urine ; and it is probable the pancreatic fecretion 
may fuller an inverfion at the fame time, though we have yet no 
mark by which this can be afcertained. 
13. Mr. ate two putrid pigeons out of a cold pigeon- 
pye, and drank about a pint of beer and ale along wuth them, 
and immediately rode about five miles. He was then fcized 
with vomiting, which was after a few periods fucceeded by purg- 
ing ; thefe continued alternately for two hours ; and the purg- 
ing continued by intervals for fix or eight hours longer. Du- 
ring this time he could not force himfelf to drink more than one 
pint in the whole ; this great inability to drink was owing to the 
naufea, or inverted motions of tl»e ftomach, which the voluntary 
exertion of fwallowing could feldom and with difficulty over- 
come ; yet he difeharged in the whole at leaft fix quarts; whence 
came this quantity of liquid ? Fir ft, the contents of the ftomach_ 
were emited, then of the duodenum, gall -bladder, and pancreas, 
by vomiting. After this the contents of the lower bowels ; then 
the chyle, that was in the latleal veffels, and in the receptacle 
of chyle, was regurgitated into the inteftmes by a retrograde mo- 
tion of thefe velfels. And afterwards the mucus difpofited in the 
cellular membrane, and on the furface of all the other mem- 
branes, feems to have been abforbed; and with the fluid abforb- 
ed from the air to have been carried by their refpeffive lymphat- 
ic branches by the increafed energy of their natural motions, and 
down the vifceral lymphatics, or lacteals, by the inverfion of 
their motions. 
14. It may be difficult to invent experiments to demonftrate 
the truth of this inver.fion of fome branches of the abfofbent fyf- 
tem, and increafed abforption of others ; but the analogy of thefe 
veflels to the inteftinal canal, and the fymptoms of many difeafes, 
render this opinion more probable than many other received 
opinions of the animal economy. 
In tlfc above inftance, after the yellow excrement was voided, 
the fluid ceafed to have any fmell, and appeared like curdled 
milk, and then thinner fluid, and fome mucus, were evacuated ; 
did not thefe feem to partake of the chyle, of the mucous fluid 
from all the cells of the body, and laftly, of the atmofpheric moif- 
» ' ture ? 222 
OF THE STOMACH 
Sect. XXV. 15. 
tare ? All thefe fafts may be eafily obferved by any one, who 
takes a brilk purge. 
15. Where the ftimulus on the ftomach, or on fome other 
part of the inteftinal canal, is ftill more permanent, not only the 
lafteal veflels, but the whole canal itfe.lf, becomes inverted from 
its aflbeiations : this is the iliac paflion, in which all the fluids 
mentioned above are thrown up by the mouth. At this time 
the valve: in the colon, from the inverted motions of that bowel, 
and the inverted action of this living valve, does not prevent the 
regurgitation of its contents. 
The ftruclure of this valve may be reprefented by a flexile 
leathern pipe (landing up from the bottom of a veflel of water : 
its Iides collapfe by the preflure of the ambient fluid, as a fmall 
part of that fluid pafles through it ; but if it has a living power^ 
and by its inverted a&ion keeps itfelf open, it becomes like a 
rigid pipe, and will admit the whole liquid to pafs. See Se6l, 
XXXIX. 2. 5. 
In this cafe the patient is averfe to drink, from the conftant 
inverfion of the motions* of the ftomach, and yet many quarts 
are daily cjedled from the ftomach, which at length fmell of ex- 
crement, and at laft feem to be only a thin mucilaginous or aque- 
ous liquor. 
From whence is it pothble, that this great quantity of fluid for 
many fucceftive days can be fupplied, after the cells of the body 
have given up their fluids, but from the atmofphere ? When 
the cutaneous branch of abforbents a£ts with unnatural ftrength, 
it is probable the inteftinal branch has its motions inverted, and 
thus a fluid is fupplied without entering the arterial fyftem. 
Could oiling or painting the Ikin give a check to this difeafe ? 
So when the ftomach has its motions inverted, the lymphatics 
of the ftomach, which are moft ftri<5tly aflbeiated with it, invert 
their motions at the fame time. But the more diftant branches 
of lymphatics, which are lefs ftridlly aflbeiated with it, aft with 
increafed energy ; as the cutaneous lymphatics in the cholera, or 
iliac paflion, above dcfcribed. And other irritative' motions be- 
come decreafed, as the pulfations of the arteries, from the extra- 
derivation or exhauftion of the fenforial power. 
Sometimes when ftronger vomiting takes place the more dif- 
tant branches of the lymphatic fyftem invert their motions with 
thofe of the ftomach, and loofe ftools arc produced, and cold 
fweats. 
So when the lafleals have their motions inverted, as during 
the operation of ftrong purges, the urinary and cutaneous ab- 
forbents have their motions increafed to fupply the want of flu- 
ld in the .blood, as in great thirft j but after a meal with fufH- 
cient Sect. XXV. id. 
AND INTESTINES. 
223 
cient potation the urine is pale, that is, the urinary abforbents 
aft weakly, no fupply of water being wanted for the blood. 
And when the inteftinal abforbents aft -too violently, as when 
too great quantities of fluid have been drunk, the urinary abforb- 
ents invert their motions to earry off the fuperfluity, which is 
a new circumftance of aflbciation, and a temporary diabetes fu- 
pervenes. 
16. I have had the opportunity of feeing four patients in the 
iliac paflion, where the ejefted material fmelled and looked like 
excrement. Two of thefe were fo exhaufted at the time I faw 
them, that more blood could not be taken from them, and as 
their pain had ceafed, and they continued to vomit up every 
thing which they drank, I fufpefted that a mortification of the 
bowel had already taken place, and as they were both women 
advanced in life, and a mortification is produced with lefs pre- 
ceding pain in old and weak people, thefe both died. The 
other two, who were both young men, had ftill pain and ftrength 
fufficient for further venefeftion, and they neither of them had 
any appearance of hernia, both recovered by repeated bleeding, 
and a fcruple of calomel given to one, and half a dram to the 
other, in very fmall pills: the ufual means of clyfters, and 
purges joined with opiates, had been in vain attempted. I have 
thought an ounce or two of crude mercury in lefs violent difeaf- 
es of this kind has been of ufe, by contributing to reftore its 
natural motion to fome part of the inteftinal canal, either by its 
weight or ftimulus ; and that hence the whole tube recovered its 
ufual aflbeiations of progreflive periftaltic motion. I have in 
three cafes feen crude mercury given in fmall dofes, as one or 
two ounces twice a day, have great effeft in flopping pertinacious 
vomitings. 
17. Befides the affeftions above defcribed, the ftomach is lia- 
ble, like many other membranes of the body, to torpor without 
confequent inflammation : as happens to the membranes about 
the head in fome cafes of hemicrania, or in general head-ach. 
This torpor of the ftomach is attended with indigeftion, and 
confequent flatulency, and with pain, which is ufually called the 
cramp of the ftomach, and is relievable by aromatics, eflential 
oils, alcohol, or opium. 
The intrufion of a gall-ftone into the common bile-duft from 
the gall-bladder is fometimes miftaken for a pain of the ftomach, 
as neither of them is attended with fever; but in the paflage of 
a gall-ftone, the pain is confined to a lefs fpace, which is exaft- 
ly where the common bile-duft enters the duodenum, as ex- 
plained in Seftion XXX. 3. Whereas in this gaftrodynia the 
pain is diffufed over the whole ftomach; and, like other difeafes 
. ik from 224 
OF THE STOMACH 
Sect. XXV. 17. 
from torpor, the pulfe is weaker, and the extremities colder, and 
the general debility greater, than in the .paiTage of a gall-ftone ; 
for in the former the debility is the confequence of the pain, in 
the latter it is the caufe of it. 
Though the firft fits of the gout, I believe, commence with 
a torpor of the liver ; and the ball of the toe becomes inflamed 
inilead of the membranes of the liver in confequenee of this tor- 
por, as a coryza or catarrh frequently fucceeds a long expofure 
of the feet to cold, as in fnow, or on a moift brick-floor; yet in 
old or exhaufted conftitutions, which have been long habituated 
to its attacks, it fometimes commences with a torpor of the ftom- 
ach, and is transferable to every membrane of the body. When 
the gout begins with torpor of the ftomach, a painful fenfation 
of cold occurs, which the patient compares to ice, with weak 
pulfe, cold extremities, and ficknefs ; this in its flighter degree is 
relievable by fpice, wine, or opium ; in its greater degree it is 
fucceedcd by fudden death, which is owing to the fympathy of 
the ftomach with the heart, as explained below. 
If the ftomach becomes inflamed in confequence of this gouty 
torpor of it, or in confequence of its fympathy with fome oth- 
er part, the danger is lefs. A ficknefs and vomiting continues 
many days, or even weeks, the ftomach rejecting every thing 
ftimulant, even opium or alcohol, together with much vifcid 
mucus; till the inflammation at length ceafes, as happens when 
other membranes, as thofe of the joints, are the feat of gouty in - 
flammation ; as obferved in Se£l. XXIV. 2. 8. 
The fympathy, or aflbciation of motions, between thofe of 
the ftomach and thofe of the heart, is evinced in many difeafes. 
Firft, many people areoccafionally affeded with an intermiflion oP 
their pulfe for a few days, which then ceafes again. In this cafe 
there is a ftop of the motion of the heart, and at the fame time a 
tendency to eruftation from the ftomach. As foon as the patient 
feels a tendency to the intermiflion of the motion of his heart, if 
he voluntarily brings up wind from his ftomach, the ftop of the 
heart does not occur. From hence I conclude that the ftop of di- 
geftion is the primary difeafe ; and that air is inftantly generated 
from the aliment, which begins to ferment, if the digeftive pro- 
cefs is impeded for a moment, (fceSebt. XXIII. 4.) pand that the 
ftop of the heart is in confequence of the aflbciation of the motions 
of thefe vifeera, as explained in Se£L XXXV. 1. 4.; but if the 
little air, which is inftantly generated during the temporary torpor 
of the ftomach, be evacuated, the digeftion recommences, and the 
temporary torpor of the heart does not follow. One patient, 
whom I lately faw, and who had been five or fix days much 
troubled with this intermiflion of a pulfation of his heart, and 
who Sect. XXV. 17. 
AND INTESTINES. 
225 
•who had hemicrania with feme fever, was immediately relieved 
from them all by lofing ten ounces of blood, which had what is 
termed an inflammatory cruft on it. 
Another inftance of this aflbciation between the motions of 
the ftomach and heart is evinced by the exhibition of an over 
dofe of foxglove, which induces an inceflant vomiting, which is 
attended with very flow, and fometimes intermitting pulfe.- 
Which continues in fpite of the exhibition of wine and opium 
for two or three days. To the fame aflbciation muft be afcri- 
bed the weak pulfe, which conftantly attends the exhibition of 
emetics during their operation. And alfo the fudden deaths, 
which have been occafioned in boxing by a blow on the ftom- 
ach ; and laftly, the fudden death of thofe, who have been long 
debilitated by the gout, from the torpor of the ftomach. See 
Sea. XXV. I. 4. 
Vol. I. 
F F 
SECT. 226 
OF GLANDS. 
Sect. XXVI. r. 
SECT. XXVI. 
OF THE CAPILLARY GLANDS AND MEMBRANES. 
I. 1. The capillary veflels are glands. 2. Their excretory duff?* 
Experiments on the mucus oj the intejlines, abdomen, cellular mem- 
brane, and on the humours of the eye. 3. Scurf on the head, cough, 
catarrh, diarrhoea, gonorrhoea. 4. Rheumatifm. Gout. Lop-1 
rofy. If. 1. The mofl minute membranes are unorganized. 2. 
Larger membranes are compofed of the ducts of the capillaries, and 
the mouths of the abforbent s. 3. Mucilaginous fluid is fecreted 
on their furfaces. III. Three kinds of rheumatifm. 
I. i. The capillary veflels are like all the other glands except' 
the abforbent fyftem, inafmuch as they receive blood from the 
arteries, feparate a fluid from it, and return the remainder by 
the veins. 
2. This feries of glands is of the moft extenfive ufe, as their 
excretory dudfs open on the whole external ikin forming its per- 
fpirative pores, and on the internal furfaces of every cavity of 
the body. Their fecretion on the fkin is termed infenfible per- 
fpiration, which in health is in part reabforbed by the mouths 
of the lymphatics, and in part evaporated in the air 5 the fecre- 
tion on the membranes, which line the larger cavities of the 
body, which have external openings, as the mouth and inteftinal 
canal, is termed mucus, but is not however coagulable by heat ; 
and the fecretion on the membranes of thofe cavities of the body, 
which have no external openings, is called lymph or water, as 
in the cavities of the cellular membrane, and of the abdomen ; 
this lymph however is coagulable by the heat of boiling water. 
Some mucus nearly as vifcid as the white of egg, which was dif- 
charged by (tool, did not coagulate, though I evaporated it to one 
fourth of the quantity, nor did the aqueous and vitreous humours 
of a {heep's eye coagulate by the like experiment ; but the fe- 
rofitv from an anafaicous leg, and that from the abdomen of a 
dropfical perfon, and the cryftalline humour of a fheep's eye, 
coagulated in the fame heat. 
3. When any of thefe capillary glands are Simulated into 
greater irritative aebions, than is natural, they fecrete a more 
copious material; and as the mouths of the abforbent fyftem, 
which open in their vicinity, are at the fame time ftimulated in- 
to greater aftion, the thinner and more faline part of the fecre- 
ted fluid is taken up again ; and the remainder is not only more 
copious but alfo more vifcid than natural. This is more or lefs 
troublefome Gzct. XXVI. r. 4. 
OF GLANDS. 
227 
troublefome or noxious according to the importance of the func- 
tions of the part affected : on the fkin and bronchiae, where this 
fecretion ought naturally to evaporate, it-becomes fo vifeid as to 
adhere io the membrane ; on the tongue it forms a pellicle, 
which can with difficulty be fcraped off; produces the feurf or! 
the heads of many people ; and the mucus, which is fpit up by 
others in coughing. On the noftrils and fauces, when the fe- 
cretion of thefe capillary glands is increafed, it is termed fimple 
catarrh ; when in the inteftlnes, a mucous diarrhoea ; and in the 
urethra, or vagina, it has the name of gonorrhoea, or fluor albus. 
4. When thefe capillary glands become inflamed, a full more 
vifeid or even cretaceous humour is produced upon the furfaces 
of the membranes, which is the caufe or the effect of rheumat- 
ifm, gout, leprofy, and of hard tumours of the legs, which are 
generally termed fcorbutic j all which will be trea ted of here- 
after. 
IL 1. The whole furface of the body, with all its cavities and 
contents, are covered with membrane. it lines every veflel, 
forms every cell, and binds together all the mufcular and per- 
haps the offeous fibres of the body ; and is itfelf therefore prob- 
ably a Ampler fubftance than thofe fibres. And as the contain- 
ing veffels of the body from the largeft to the lead are thus lined 
and connected with membranes, it follows that thefe membranes 
themfelves confift of unorganized materials. 
For however fmall we may conceive the diameters of the 
minuteft veffels of the body, which efcape our eyes and glafles, 
vet thefe veffels muft confift of coats or fides, which are made 
up of an unorganized material, and which are probably produ- 
ced from a gluten, which hardens after its production, like the 
filk or web of caterpillars and fpiders. Of this material confift 
the membranes, which line the fhells of eggs, and the fhell itfelf, 
both which are unorganized, and are formed from mucus, which 
hardens after it is formed, either by the abforption of its more 
fluid part, or by its uniting with feme part of the atmofphere. 
Such is alfo the production of the fhells of fnails, and of fhell- 
fifh, and I fuppofe of the enamel of the teeth. 
2. But though the membranes, that compofe the fides of the 
moft minute veffels, are in truth unorganized materials, yet the 
larger membranes, which are perceptible to the eye, feeni to be 
compofed of an intertexture of the mouths of the abforbent fyf- 
tem, and of the excretory dufts of the capillaries, with their con- 
comitant arteries, veins, and nerves : and from this conftruftion 
it is evident, that thefe membranes muft poffefs great irritability 
to peculiar ftimuli, though they are incapable of any motions, 
that are vifible to the naked eye : and daily experience (hews us, 
that 228 
OF GLANDS. 
Sect. XXVI. 2. 3. 
that in their inflamed Rate they have the greateft fenfibility to 
pain, as in the pleurify and paronychia. 
3. On all thefe membranes a mucilaginous or aqueous fluid is 
fecreted, which moiftens and lubricates their furfaces, as was 
explained in Sedion XXIII. 2. Some have doubted, whether 
this mucus is feparated from the blood by an appropriated fet of 
gljfhds, or exudes through the membranes, or is an abrafion or 
deftruftion of the furface of the membrane itfelf, which is con- 
tinually repaired on the other fide of it, but the great analogy 
between the capillary veflels, and the other glands, countenances 
the former opinion j and evinces, that thefe capillaries are the 
glands, that fecrete it ; to which we muft add, that the blood in 
palling thefe capillary veflels undergoes a change in its colour 
from florid to purple, and gives out a quantity of heat ; from 
whence, as in other glands, we muft conclude that fomething 
is fecreted from it. 
HI. The feat of rheumatifm is in the membranes, or upon 
them ; but there are three very diftindt difeafes, which com- 
monly are confounded under this name. Firft, when a mem- 
brane becomes affected with torpor or inactivity of the veflels 
which compofe it, pain and coldnefs fucceed, as in the hemicra- 
nia, and other head-achs, which are generally termed nervous 
rheumatifm ; they exift whether the part be at reft or in motion, 
and are generally attended with other marks of debility. 
Another rheumatifm is faid to exift, when inflammation and 
fwelling, as well as pain, affect fome of the membranes of the 
joints, as of the ancles, wrifts, knees, elbows, and fometimes of 
the ribs. This is accompanied with fever, is analogous to pleu- 
rify and other inflammations, and is termed the acute rheu- 
matifm. 
A third difeafe is called chronic rheumatifm, which is diftin- 
guifhed from that firft mentioned, as in this the pain only af- 
feCts the patient during the motion of the part, and from the 
fecond kind of rheumatifm above defcribed, as it is not attend- 
ed with quick pulfe or inflammation. It is generally believed 
to fucceed the acute rheumatifm of the fame part, and that fome 
coagulable lymph, or cretaceous, or calculous material, has 
been left on the membrane ; which gives pain, when the muf- 
cles move over it, as fome extraneous body would do, which was 
too infoluble to be abforbed. Hence there is an analogy be- 
tween this chronic rheumatifm and the difeafes which produce 
gravel or gout-ftones ; and it may perhaps receive relief from 
the fame remedies, fuch as aerated fal foda. 
SECT §ECT. XXVII. I. I. 
OF HAEMORRHAGES. 
229 
SECT. XXVII. 
OF HAEMORRHAGES. 
J. veins are abforbent veflels. I. Hemorrhages from inflow 
mation. Cafe of hemorrhagefrom the kidney cured by cold bathing. 
Cafe of hemorrhage from the nofe cured by cold immerfton. If. 
Hemorrhage from venous paralyfis. Of piles. Black flools. 
P'etechie. Confumption. Scurvy of the lungs. Blacknefs oj the 
face and eyes in epilepticfits. Cure of hemorrhages from venous 
inability. 
I. As the imbibing mouths of the abforbent fyftem already 
described open on the furface, and into the larger cavities of the 
body, fo there is another fyftem of abforbent veflels, which are 
not commonly efteemed fuch, I mean the veins, which take up 
the blood from the various glands and capillaries, after their prop- 
er fluids or fecretions have been feparated from it. 
The veins refemble the other abforbent veflels ; as the progref- 
fion of their contents is carried on in the lame manner in both, 
they alike abforb their appropriated fluids, and have valves to 
prevent its regurgitation by the accidents of mechanical vio- 
lence. This appears firft, becaufe there is no pulfation in the 
very beginnings of the veins, as is feen by microfcopes ; which 
muft happen, if the blood was carried into them by the actions 
of the arteries. For though the concurrence of various venous 
ftreams of blood from different diftances muft prevent any pul- 
fation in the larger branches, yet in the very beginnings of all 
thefe branches a pulfation muft unavoidably exift, if the circula- 
tion in them was owing to the intermitted force of the arteries. 
Secondly, the venous abforption of blood from the penis, and 
from the teats of female animals after their erection, isftill more 
fmailar to the lymphatic abforption, as it is previoufly poured in- 
to cells, where all arterial impulfe muft ceafe. 
There is an experiment, which feems to evince this venous 
abforption, which confifts in the external application of a ftimu- 
lus to the lips, as of vinegar, by which they become inftantly 
pale ; that is, the bibulous mouths of the veins by this ftimulus 
are excited to abforb the blood fafter, than it can be lupplied by 
the ufual arterial exertion. See Se<ft. XXIII. 5. 
1. There are two kinds of haemorrhages frequent in difeafes, 
one is where the glandular or capillary addion is too powerfully ex- 
erted, and propels the blood forwards more haftily, than the veins 
can abforb it ; and the other is, where the abforbent power of 
the 230 
OF HEMORRHAGES. 
Sect. XXVII. i. rf 
the veins is diminifhed, or a branch of them is become totally 
paralytic. 
The former of thefe cafes is known by the heat of the part, 
and the general fever or inflammation that accompanies the haem- 
orrhage. A haemorrhage from the nofe or from the lungs is 
fometimes a crifis of inflammatory difeafes, as of the hepatitis 
and gout, and generally ceafes fpontaneoufly, when the veflels 
are confiderably emptied. Sometimes the haemorrhage recurs 
by daily periods accompanying the hot fits of fever, and ceafing 
jn the cold fits, or in the intermiflions ; this is to be cured by re- 
moving the febrile paroxyfms, which will be treated of in their 
place. Otherwife it is cured by venefeclion, by the internal or 
external preparations of lead, or by the application of cold, with 
an abflennous diet, and diluting liquids, like other inflammations. 
Which by inducing a quiefcence on thofe glandular parts, that 
are affected, prevents a greater quantity of blood from being 
protruded forwards, than the veins are capable of abforbing. 
Mr. B had a haemorrhage from his kidney, and parted 
•with not lefs than a pint of blood a day (by conjecture) along 
with his urine for above a fortnight: venefedlions, mucilages, 
balfams, preparations of lead, the bark, alum, and dragon's blood, 
opiates, with a large blifter on his loins, were feparately tried, in 
large dofes, to no purpofe. He was then directed to bathe in a 
cold fprlng up to the middle of his body only, the upper part be- 
ing covered, and the haemorrhage diminifhed at the firfl, and 
ceafed at the fecond immerfion. 
In this cafe the external capillaries were rendered quiefeent by 
the «oldnefs of the water, and thence a lefs quantity ©f blood 
was circulated through them ; and the internal capillaries, or 
other glands, became quiefeent from their irritative aflbeiations 
with the external ones ; and the haemorrhage was flopped a fuf- 
ficient time for the ruptured veflels to contract their apertures, 
or for the blood in thofe apertures to coagulate. 
Mrs. K had a continued haemorrhage from her nofe 
for fome days ; the ruptured veflel was not to be reached by plugs 
up the ncflrils, and the fen Ability of her fauces was fuch that 
nothing could be borne behind the uvula. After repeated vene- 
leclion, and other common applications, fhe was diredied to im- 
merfe her whole head into a pail of water, which was made cold- 
er by the addition of feveral handfuls of fait, and the haemorrhage 
immediately ceafed, and returned no more ; but her pulfe con- 
tinued hard, and fhe was neceflitatcd to lofe blood from the arm 
on the fucceeding day. 
Query, might not the cold bath inftantly flop haemorrhages 
from the lungs in inflammatory cafes ?-for the fhortnefs of 
J breath Sect. XXVII. 2. 1. 
OF HEMORRHAGES 
231 
breath of thofe, who go fuddenly into cold water, is not owing- 
to the accumulation of blood in the lungs, but to the quiefcence of 
the pulmonary capillaries from affociation, as explained in Sec- 
tion XXXII. 3. 2. 
IL The other kind of haemorrhage is known from its being at- 
tended with a weakpulfe, and other fymptoms of general debil- 
ity, and very frequently occurs in thofe, who have difealed livers, 
owing to intemperance in the ufe of fermented liquors. Thefe 
conftitutions are (hewn to be liable to paralylis of the lymphatic 
abforbents, producing the various kinds of droplies in Setlion 
XXIX. 5. Now if any branch of the venous fyftem lofes its 
power of abforption, the part fwells, and at length burfts and 
clifeharges the blood, which the capillaries or other glands circu- 
late through them. 
It fometimes happens that the large external veins of the legs 
burft, and effufe their blood ; but this occurs moft frequently in 
the veins of the inteftines, as the vena portarum is liable to fuf- 
fer from a fchirrus of the liver oppoling the progreflion of the 
blood, which is abforbed from the inteltines. Hence the piles 
are a fymptom of hepatic obftrudlion, and hence the copious dif- 
charges downwards or upwards of a black material, which has 
been called melancholia, or black bile; but is no other than the 
blood, which is probably difeharged from the veins of the intef- 
iines. 
J. F. Meckel, in hisExpcrimcnta deFinibusVaforum,publilhed 
at Berlin, 1772, mentions his difeovery of a communication of 
a lymphatic vefTel with the galtric branch of the vena portarum. 
It is poffible, that when the motion of the lymphatic becomes 
retrograde in fome difeafes, blood may obtain a paflage into it, 
where it anaftomofes with the vein, and thus be poured into the 
inteftines. A difeharge of blood with the urine fometimes at- 
tends diabetes, and may have its fource in theTarne manner. 
Mr. A , who had been a hard drinker, and had the 
gutta rofacea on his face and breaft, after a ftroke of the palfy 
voided near a quart of a black vifeid material by ftool : on diluting 
it with water it did not become yellow, as it mult have done if 
it had been infpiffated bile, but continued black like the grounds 
of coffee. 
But any other part of the venous fyftem may become quiefeent 
or totally paralytic as well as the veins of the inteftines : all which 
occur more frequently in thofe who have difeafed livers, than in 
any others. Hence troublefome bleedings of the nofe, or from the 
lungs with a weak pulfe; hence haemorrhages from the kidneys, 
too great menftruation; and hence the oozing of blood from 
every part of the body, and the petechiae in thofe fevers, which 
are 232 
OF HEMORRHAGES. 
Sect. XXVII. 2. 
are termed putrid, and which iserroneoufly afcribed to the thin- 
nefs of the blood : for the blood in inflammatory difeafes is equal- 
ly fluid before it coagulates in the cold air. 
Is not that hereditary confumption, which occurs chiefly in 
darkeyed people about the age of twenty, and commences 
with flight pulmonary haemorrhages without fever, a difeafe of 
this kind ?-Thefe haemorrhages frequently begin during fleep, 
when the irritability of the lungs is not fufficient in thefe patients 
to carry on the circulation without the afliftance of volition ; for 
in our waking hours, the motions of the lungs are in part volun- 
tary, efpecially if any difficulty of breathing renders the efforts 
of volition neceffary. See Clafs I. 2. 1. 3. and Clafs III. 2. 1. 
12. Another fpecies of pulmonary confumption which feems 
more certainly of fcrofulous origin is defcribed in the next Sec- 
tion, No. 2. 
I have feen two cafes of women, of about forty years of age, 
both of whom were feized with quick weak pulfe, with difficult 
refpiration, and who fpit up by coughing much vifeid mucus 
mixed with dark coloured blood. They had both large vibices 
on their limbs, and petechiae ; in one the feet were in danger of 
mortification, in the other the legs were oedematous. To relieve 
the difficult refpiiation, about fix ounces of blood were taken 
from one of them, which to my furprife was fizy, like inflamed 
blood : they had both palpitations or unequal pulfations of the 
heart. They continued four or five weeks with pale and bloat- 
ed countenances, and did not ceafe fpitting phlegm mixed with 
black blood, and the pulfe feldom flower than 130 or 135 in a 
minute. This blood, from its dark colour, and from the many 
vibices and petechise, feems to have been venous blood; the 
quicknefs of the pulfe, and the irregularity of the motion of the 
heart, are to be afcribed to debility of that part of the fyftem ; 
as the extravafation of blood originated from the defeat of ven- 
ous abforption. The approximation of thefe two cafes to fea- 
feurvy is peculiar, and may allow them to be called fcorbutus 
pulmonalis. Had thefe been younger fubjedls, and the paraly- 
fis of the veins had only affected the lungs, it is probable the 
difeafe would have been a pulmonary confumption. 
Laft week I faw a gentleman of Birmingham, who had for 
ten days laboured under great palpitation of his heart, which 
was fo diftimStly felt by the hand, as to difcountcnance the idea 
of there being a fluid in the pericardium. He frequently fpit 
up mucus ftained with dark coloured blood, his pulfe very un- 
equal and very weak, with cold hands and nofe. He could not 
lie down at all, and for about ten days paft could not fleep a min- 
ute together, but waked perpetually with great uneafinefs. 
Could Sect. XXVII. 2. 1. 
OF HEMORRHAGES. 
233 
Could thofe fymptoms be owing to very extenfive adhefions of 
the lungs ? or is this a fcorbutus pulmonalis ? After a few days 
he fuddenly got fo much better as to be able to fleep many hours 
at a time by the ufe of one grain of powder of foxglove twice a 
day, and a grain of opium at night. After a few days longer, the 
bark was exhibited, and the opium continued with fome wine ; 
and the palpitations of his heart became much relieved, and he 
recovered his ufual degree of health, but died fuddenly fome 
months afterwards. 
In epileptic fits the patients frequently become black in the face, 
from the temporary paralyfis of die venous fyftem of this part, 
I have known two inltances where the blacknefs has continued 
many days. M. P , who had drank intemperately, was 
feized with the epilepfy when he was in his fortieth year; in 
one of thefe fits the white part of his eyes was left totally black 
with eflufed blood ; which was attended with no pain or heat, 
and was in a few weeks gradually abforbed, changing colour as 
is ufual with vibices from bruifes. 
The haemorrhages produced from the inability of the veins to 
abforb the refluent blood, are cured by opium, the preparations 
of fteel, lead, the bark, vitriolic acid, and blitters ; but thefe have 
the eflecSt with much more certainty, if a venefedtion to a few 
ounces, and a moderate cathartic with four or fix grains of cal- 
omel be premifed, where the patient is not already too much de- 
bilitated ; as one great means of promoting the abforption of 
any fluid confifts in previoufly emptying the veifels, which are 
to receive it. 
Vol. I. 
G G 
SECT. 234 
PARALYSIS OF 
Sect. XXVHE i. 
SECT. XXVIIL 
OF THE PARALYSIS OF THE ABSORBENT SYSTEM. 
I. Paralyfis of the laPeals, atrophy. Difafe to animal food. IL 
Caufe of dropfy. Caufe of herpes. Scrofula. Mefenteric con* 
fumption. Pulmonary confumption. Why ulcers in the lungs are 
fo diff cult to heal. 
The term paralyfis has generally been ufed to exprefs the lofs 
of voluntary motion, as in the hemiplegia, but may with equal 
propriety be applied to exprefs the d^fobediency of the mufcu- 
lar fibres to the other kinds of ftimulus; as to thole of irritation 
or fenfation. 
I. There is a fpecies of atrophy, which .has not been well un- 
derftood; when the abforbent veffels of the ftomach and intef- 
tines have been long inured to the ftimulus of too much f irit- 
uous liquor, they at length, either by the too fudden omiflpn of 
fermented or fpirituous potation, or from the gradual dec^y of 
nature, become in a certain degree paralytic ; now it is obferv- 
ed in the larger mufcles of the body, when one fide is paralytic, 
the other is more frequently in motion, owing to the lefs expen- 
diture of fenforial power in the paralytic limbs ; fo in this cafe 
the other part of the abforbent fyftem atls with greater force, 
or with greater perfeverance, in confequence of the paralyfis of 
the la<£leals ; and the body becomes greatly emaciated in a fmall 
time. 
I have feen feveral patients in this difeafe, of which the fol- 
lowing are the circumftances. i. They were men about fifty 
vears of age, and had lived freely in refpect to fermented liquors. 
2. They loft their appetite to animal food. 3. They became 
fuddenly emaciated to a great degree. 4. Their fkins were dry 
and rough. 5. They coughed and expectorated with difficulty 
a vifeid phlegm. 6. The membrane of the tongue was dry 
and red, and liable to become ulcerous. 
The inability to digeit animal food, and the confequent dif- 
tafte to it, generally precede the dropfy, and other difeafes, 
which originate from fpirituous potation. I fuppofe when the 
ftomach becomes inirritable, that there is at the lame time a de- 
ficiency of gaftric acid ; hence milk feldom agrees with thefe 
patients, unlefs it be previoufly curdled, as they have not fuffi- 
cient gaftric acid to curdle it; and hence vegetable food, which 
is itfclf acefcent, will agree with their ftomachs longer than an- 
imal food, which requires more of the gaftric acid for its digeftion. 
* In Sect. XXVIII. 2. 
ABSORBENTS. 
235 
In this difeafe the Ikin is dry from the increafed abforption of 
the cutaneoas lymphatics, the fat is abforbed from the increafed 
abforption of the cellular lymphatics, the mucus of the lungs 
is too vifcid to be eafily fpit up by the increafed abforption of 
the thinner parts of it, the membrana fneideriana becomes dr^y, 
covered with hardened mucus, and at length becomes inflamed 
and full of apthae, and either thefe Houghs, or pulmonary ulcers, 
terminate the feene. 
II. The immediate caufe of dropfy is the paralyfis of fome 
other branches of the abforbent fyltem, which are called lym- 
phatics, and which open into the larger cavities of the body, or 
into the cells of the cellular membrane ; whence thofe cavities 
or cells become diltended with the fluid, which is hourly fecre- 
ted into them for the purpole of lubricating their furfaces. As 
is more fully explained in No. 5. of the next Section. 
As thofe lymphatic veflels confift generally of a Jong neck or 
mouth, which drinks up its appropriated fluid, and of a conglob- 
ate gland, in which this fluid undergoes fome change, it hap- 
pem that fometimes the mouth of the lymphatic, and fometimes 
the oelly or glandular part of it, becomes totally or partially par- 
alytic. In tire former cafe, where the mouths of the cutaneous 
lymphatics become torpid or quiefeent, the fluid fecreted on the 
Ikin ceafesto be abforbed, and erodes the ficin by its faline acri- 
mony, and produces eruptions termed herpes, the difeharge from 
which is as fait,as the tears,which arefecreted too faft to be reab- 
forbed, as in grief, or when the punfta lacrymalia are obftructed, 
and which running down the cheek redden and inflame the fkin. 
When the mouths of the lymphatics, which open on the mu- 
cous membrane of the noltrils, become torpid, as on walking into 
the air in a frofty morning ; the mucus, which continues to be fe- 
creted, has not its aqueous and faline part reabforbed which run- 
ning over the upper lip inflames it, and has a fait taite, if it falls 
on the tongue. 
When the belly, or glandulaV part of one of thefe lymphatics, 
becomes torpid, -the fluid abforbed by its mouth ftagnates, and 
forms a tumour in the gland. This difeafe is called the fcrofula. 
If thefe glands fuppurate externally, they gradually heal, a? thofe 
of the neck 5 if they fuppurate without an opening on the ex- 
ternal habit, as the mefenteric glands, a heftic fever enfues, which 
deftroys the patient; if they fuppurate in the lungs, a pulmonary 
confumption enfues, which is believed thus to differ from that 
defcribed in the preceding Section, in refpedt to its feat or prox- 
imate caufe. 
It is remarkable, that matter produced by fuppuration will lie 
concealed in the body many weeks, or even months, without pro- 
ducing 236 
PARALYSIS OF 
Sect. XXVIII. 2. 
ducing heflic fever ;'but as foon as the wound is opened, fo as 
to admit air to the furface of the ulcer, a hectic fever fupervenes, 
even in very few hours, which I formerly conceived to be owing 
to the azotic part of the atmofphere rather than to the oxygene; 
becaufe thofe medicines, which contain much oxygene, as the 
calces or oxydes of metals, externally applied, greatly contribute 
to heal ulcers; of thefe are the folutions of lead, and mercury, 
and copper in acids, or their precipitates ; but have fince believed 
it to be owing to the oxygene. See Clafs II. i. 6. 7. in Vol. II. 
of this work. 
Hence when wounds are to be healed by the firft intention, 
as it is called, it is neceflary carefully to exclude the air from 
them. Hence we have one caufe, which prevents pulmonary ul- 
cers from healing, which is their being perpetually expofed to the 
air. 
Another caufe of the difficulty of healing pulmonary ulcers 
may arife from the inactivity of the veRels of the air-cells, which 
are covered with a membrane differing both from that of the mu- 
cous membranes of other cavities of the body, and from the ex- 
ternal ikin. For it is probable, that the air-cells alone of the 
lungs conftitute the organ of refpiration, and not the internal fur- 
faces of the branching veffels of the trachea which lead to the 
air-cells. And from a vegetable analogy mentioned below they 
probably exhale or perfpire either nothing or much lefs than the 
furfaces of the pulmonary veffels, which lead to them. Hence 
the mucus, which in common coughs or fuperficial peripneumo- 
ny is fecreted on the furface of the branching veffels of the lungs, 
is forced up in coughing by the air behind it, which is haftily ex- 
cluded from the air-cells, and Howly inhaled into them. But if 
there was any mucus or matter formed in thefe air-cells, it is not 
eafy to underftand how it could be brought up by coughing, as 
no air could get admittance behind it; which may be one caufe 
of the difficulty of healing pulmonary ulcers if they exift on the 
furface of the air-cells ; but not fo, if they exift in the veffels 
leading to the air-cells, as after a wound with a fword, or when 
a vomica has burft after a peripneumony. 
In the vegetable fyftem, I think, there can be no doubt, but 
that the upper furface of the leaves conftitutes the organ of ref- 
piration, and M. Bonnet in his Ufage des Feuilles Ihows by a 
curious experiment, that the upper furfaces of leaves do not ex- 
hale half fo much as their under furfaces. He placed the ftalks 
of many leaves frefli collected into glafs-tubes filled with water, 
of many of thefe the upper furfaccs were fmeared with oil, and 
the under furfaces of many others of them ; and he uniformly 
found Sect. XXVIII. 2. 
ABSORBENTS. 
237 
found by the finking of the water in the tubes, that the upper 
furfaces exhaled lefs by half than the under furfaces. 
Both the dark-eyed patients, which are.affefted with pulmo- 
nary ulcers from deficient venous abforption, as defcribcd in Sec- 
tion XXVII. 2. and the light-eyed patients from deficient lym- 
phatic abforption, which we are now treating of, have generally 
large apertures of the iris ; thefe large pupils of the eyes are a 
common mark of want of irritability ; and it generally happens, 
that an increafe of fenfibility, that is, of motions in confequence 
of fenfation, attends thefe conftitutions. See Seel. XXXI. 2. 
Whence inflammations may occur in thefe from ftagnated fluids 
more frequently than in thofe conftitutions, which poflefs more 
irritability and lefs fenfibility. 
Great expectations in refpe£l to the cure of confumptipns, 
as well as of many other difeafes, are produced by the very in- 
genious exertions of Dr. Beddoes ; who has eltabliihed an ap- 
paratus for breathing various mixtures of airs or gafles, at the 
hot-wells near Briltol, which well deferves the attention of the 
public. 
Dr. Beddoes very ingenioufly concludes, from the florid col- 
our of the blood of confumptive patients, that it abounds in ox- 
ygene ; and that the rednefs of their tongues, and lips, and the 
fine blufh of their cheeks, fliew the prefence of the fame prin- 
ciple, like flefh reddened by nitre. And adds, that the circum- 
ftance of the confumptions of pregnant women being flopped 
in their progrefs during pregnancy, at which time their blood 
may be fuppofed to be in part deprived of its oxygene, by ox- 
ygenating the blood of the foetus, is a forcible argument in fa- 
vour of this theory ; which mult foon be confirmed or con- 
futed by his experiments. See Eflay on Scurvy, Confumption, 
&c. by Dr. Beddoes. Murray. London. Alfo Letter to Dr« 
Darwin by the fame. Murray. London. 
SECT. 238 
RETROGRADE 
Sect. XXIX. i. i. 
SEC T. XXIX. 
ON THE RETROGRADE MOTIONS OF THE ABSORBENT SYSTEM 
I. Account of the abforbent fy/lem. II. The valves of the abforbent 
vefels may fuffer their fluids to regurgitate in fame difeafes. III. 
Communication from the alimentary canal to the bladder by means 
of the abforbent veffels. IV. The phenomena of diabetes explained. 
'V. i. The phenomena of dropfies explained. 2- Cafes of the ufe 
of foxglove. VI. Of cold fweats. VIL Tranfations of matter , 
oj chyle, of milk, of urine, operation of purging drugs applied ex- 
ternally. VIII. Circumfances by 'which the fluids^ that are ef- 
fifed by the retrograde motions of the abforbent vefels, are dfin- 
guifhed. IX. Retrograde motions of vegetabe juices. X- Ob- 
jections anfwered. XI. The caufes, which induce the retrograde 
motions of animal veffels, and the medicines by which the natural 
motions are refored. 
IT. B. The following Section is a tranfation of apart of a Latin the- 
Jis written by the late Mr. Charles Darwin, which was printed 
with his prize-differtation on a criterion between matter and mu- 
cus in 1780. Sold by Cadell, London. 
I. Account of the Alfrbent Syfcm. 
i. The abforbent fyftem of vefiels in animal bodies confifts 
of feveral branches, differing in refpeft to their fituations, and 
to the fluids, which they abforb. 
The inteftinal abforbents open their mouths on the internal 
furfaccs of the inteflines ; their office is to drink up the chyle 
and rhe other fluids from the alimentary canal; and they are 
termed la&eals, to diftinguifh them from the other abforbent vef- 
fels, which have been termed lymphatics. 
Thofe, whofe mouths are difperfed on the external fkin, im- 
bibe a great quantity of water from the atmofphere, and a part 
of the perfpirable matter, which does not evaporate, and are 
termed cutaneous abforbents. 
Thofe, which arife from the internal furface of the bronchia, 
and which imbibe moifture from the atmofphere, and a part of 
the bronchial mucus, are called pulmonary abforbents. 
Thofe, which open their innumerable mouths into the cells of 
the whole cellular membrane ; and whofe ufe is to take up the 
fluid, which is poured into thofe cells, after it has done its of. 
lice there ; may be called cellular abforbents. 
Thofe, which arife from the internal furfaces of the mem. 
branesj Sect. XXIX. 1. 2. 
ABSORBENTS. 
239 
branes, which line the larger cavities of the body, as the thorax, 
abdomen, fcrotum, pericardium, take up the mucus poured in- 
to thofe cavities ; and are diftinguifhed by the names of their re- 
fpeftive cavities. 
Whilft thole, which arife from the internal furfaces of the 
urinary bladder, gall-bladder, falivary du<fts, or other receptacles 
of fecreted fluids, may take their names from thofe fluids ; the 
thinner parts of which it is their office to abforb : as urinary, 
bilious, or falivary abforbents. 
2- Many of thefe abforbent veflels, both la£teals and lymphat- 
ics, like fome of the veins, are replete with valves : which feem 
dtfigned to affift the progrefs of their fluids, or at leaft to pre- 
vent their regurgitation ; where they are fubjefted to the inter-* 
mitted preflure of the mufcular, or arterial actions in their 
neighbourhood. 
Thefe valves do not however appear* to be neceflary to all the 
abforbents, any more than to all the veins ; fince they are not 
found to exif! in the abforbent fyitem of fiffi ; according to the 
difeoveries of the ingenious, and much lamented Mr. Hewfon. 
Philof. Tranf. v. 59, Enquiries into the Lymph. Syft. p. 94. 
3. Thefe abforbent veflels are alfo furnifhed with glands, 
which are called conglobate glands ; whofe ufe is not at prefent 
fufficiently inveftigated ; but it is probable that they refemble 
the conglomerate glands both in ftrudlure and in ufe, except that 
their abforbent mouths are for the conveniency of fituation placed 
at a greater diftance from the body of the gland. The con- 
glomerate glands; open their mouths immediately into the fan- 
guiferous veflels, which bring the blood, from whence they ab- 
forb their refpeefive fluids, quite up to the gland ; but thefe 
conglobate glands collect their adapted fluids from very diftant 
membranes, or cyfts, by means of mouths furnifhed with long 
necks for this purpofe ; and which are called ladfeals, or lym- 
phatics. 
4. The fluids, thus collected from various parts of the body, 
pafs by means of the thoracic dudl into the left fubclavian near 
the jugular vein ; except indeed that thofe collected from the 
right fide of the head and neck, and from the right arm, are car- 
ried into the right fubclavian vein : and fometimes even the 
lymphatics from the right fide of the lungs are inferted into 
the right fubclavian vein : whilft thofe of the left fide of the 
head open but juft into the fummit of the thoracic du<T. 
5 . In the abforbent fyftem there are many anaftomofes of the 
veflels, which feem of great confequence to the prefervation of 
health. Thefe anaftomofes are difeovered by dilfe£lion to be 
very 240 
RETROGRADE 
Sect. XXIX. i.6> 
very frequent between the inteflinal and urinary lymphatics, as 
mentioned by Mr. Hewfon, (Phil. Tranf. v. 58.) 
6. Nor do all the inteflinal abforbents feem to terminate in the 
thoracic duel, as appears from fome curious experiments of D. 
Munro, who gave madder to fome animals, having previoufly 
put a ligature on the thoracic dudl, and found their bones and 
the ferum of their blood coloured red. 
II. The Valves of the Abforbent S\fem may fufer their Fluids to re- 
gurgitate in fame Difeafes. 
i. The many valves, which occur in the progrefs of the lym - 
phatic and lacteal vefiels, would feem infuperable obstacles to 
the regurgitation of their contents. But as thefe valves are 
placed in vefiels, which are indued with life, and are themfelves 
indued with life alfo •, and are very irritable into thofe natural 
motions, which abforb, or propel the fluids they contain ; it is 
poflible, in fome difeafes, where thefe valves or vefiels are ftimu- 
lated into unnatural exertions, or are become paralytic, that dur- 
ing the diaftole of the part of the veflel to which the valve is at- 
tached, the valve may not fo completely clofe, as to prevent the 
relapfe of the lymph or chyle. This is rendered more probable, 
by the experiments of injecting mercury, or water, or fuet, or by 
blowing air down thefe vefiels : all which pafs the valves very 
eafily, contrary to the natural courfe of their fluids, when the 
vefiels are thus a little forcibly dilated, as mentioned by Dr. Hal- 
ler, Elem. Phyfiol. t. iii. f. 4. 
" The valves of the thoracic dudt are few, fome afiert they 
are not more than twelve, and that they do not very accurately 
perform their office, as they do not clofe the whole area of the 
duft, and thence may permit chyle to repafs them downwards. 
Tn living animals, however, though not always, yet more frequent- 
ly than in the dead, they prevent the chyle from returning. The 
principal of thefe valves is that, which prefides over the infer- 
tion or the thoarcic duct, into the fubclavian vein •, many have 
believed this alfo to perform the office of a valve, both to admit 
the chyle into the vein, and to preclude the blood from entering 
the dudt; but in my opinion it is fcarcely fufficient for this pur- 
pofe." Haller, Elem. Phyf. t. vii. p. 226. 
2. The mouths of the lymphatics feem to admit water to pafs 
through them after death, the inverted way, eafier than the nat- 
ural one ; fmee an inverted bladder readily lets out the water 
with which it is filled ; whence it may be inferred, that there is 
no obftacle at the mouths of thefe vefiels to prevent the regurgi- 
tation of their contained fluids. 
I Sect. XXIX. 2. 3. 
ABSORBENTS. 
241 
I was induced to repeat this experiment, and having accurate- 
ly tied the ureters and neck of a frefh ox's bladder, 1 made an 
opening at the fundus of it ; and then, having turned it infide 
outwards, filled it half full with water, and was furprifed to fee 
it empty itfelf fo haftily. I thought the c?<periment more ap- 
pofite to my purpofe by fufpending the bladder with its neck 
downwards, as the lymphatics are chiefly fpread upon this part 
of it, as (hewn by Dr. Watfon, Philof. Tranf. v. 59. p. 392. 
3. In fome difeafes, as in the diabetes, and fcrofula, it is prob- 
able the valves themfelves are difeafed, and are thence incapable 
of preventing the return of the fluids they fhould fupport. Thus 
the valves of the aorta itfelf have frequently been found feirrhous, 
according to the difleClions of Monf. Lieutaud, and have given 
rife to an interrupted pulfe, and laborious palpitations, by buffer- - 
ing a return of part of the blood into the heart. Nor are any 
parts of the body fo liable to feirrhofity as the lymphatic glands 
and veflels, infomuch that their feirrhofities have acquired a dif- 
tinft name, and been termed fcrofula. 
4. There are valves in other parts of the body, analogous to 
thofe of the abforbent byftem, and which are liable, when difeaf- 
ed, to regurgitate their contents : thus the upper and lower orifi- 
ces of the ftomach are clofed by valves, which, when too great 
quantities of warm water have been drunk with a deflgn to pro- 
mote vomiting, have fometimes refilled the utmoft efforts of the 
abdominal mufcles, and diaphragm : yet, at other times, the up- 
per valve, or cardia, eafily permits the evacuation of the contents 
of the ftomach ; whilft the inferior valve, or pylorus, permits the 
bile, and other contents of the duodenum, to regurgitate into 
the ftomach. 
5. 'Ihe valve of the colon is well adapted to prevent the re- 
trograde motion of the excrements ; yet, as this valve is poflefl- 
ed of a living power, in the iliac paifion, either from bpafin, or 
other unnatural exertions, it keeps itfelf open, and either buffers 
or promotes the retrograde movements of the contents of the 
inteftines below ; as in ruminating animals the mouth of the 
firft ftomach feems to be fo conftruCied, as to facilitate or affift 
the regurgitation of the food ; the rings of the oebophagus after- 
wards contracting themfelves in inverted order. De Ilaen, bv 
means of a fyringe, forced fo much water into the reClum intef- 
tinum of a dog, that he vomited it in a full ftream from his 
mouth ; and in the iliac paflion above mentioned, excrements 
and clyfter are often evacuated by the rtiouth. bee Sctlioii 
XXV. 15. 
6. The punCta lacrymalia, with the lacrymal fack and nabat 
dm% compofe a complete gland, and much refemble the inteb- 
Vol. I. W h tinal 242 
RETROGRADE 
Sect. XXIX. 2. 
tinal canal: the punfta lacrymalia are abforbent mouths, that 
take up the tears from the eye, when they have done their of* 
lice there, and convey them into the noftrils ; but when the naf- 
al dud is obflruded, and the lacrymal fack diftended with its 
fluid, on preflure with the finger the mouths of this gland 
(punda lacrymalia) will readily difgorge the fluid, they had pre- 
vioufly abforbed, back into the eye. 
7. As the capillary veflels receive blood from the arteries, 
and feparating the mucus, or perfpirable matter from it, convey 
the remainder back by the veins ; thefe capillary veflels are a fee 
of glands, in every refped fimilar to the fecretory veflels of the 
liver, or other large congeries of glands. The beginnings of 
thefe capillary veflels have frequent anaftomofis into each other, 
in which circumftance they are refembled by the ladeals ; and 
like the mouths or beginnings of other glands, they are a fet 
of abforbent veflels, which drink up the blood which is brought 
to them by the arteries, as the chyle is drunk up by the ladeals : 
for tfie circulation of the blood through the capillaries is proved 
to be independent of arterial impulfe; fince in the blufh of 
ihame, and in partial inflammations, their adion is increafed, 
without any increafe of the motion of the heart. 
8. Yet not only the mouths, or beginnings of thefe anaflomo- 
fing capillaries are frequently feen by microicopes, to regurgitate 
fome particles of blood, during the ftruggles of the animal; but 
retrograde motion of the blood, in the veins of thofe animals, 
from the very heart to the extremity of the limbs, is obfervable, 
by intervals, during the diftrefles of the dying creature. Haller, 
Elem. Phyfiol. t. i. p. 216. Now, as the veins have perhaps 
all of them a valve fomewhere between their extremities and 
the heart, here is ocular demonftration of the fluids in this difeaf- 
ed condition of the animal, repafling through venous valves : 
and it is hence highly probable, from the ftridefl analogy, that 
if the courfe of the fluids, in the lymphatic veflels, could be fub- 
jeded to microfcopic obfervation, they would allo, in the difeai- 
ed Hate of the animal, be feen to repafs the valves, and the 
mouths of thofe veflels, which had previoufly abforbed them, or 
promoted their progreflion. 
Mr. Cooper relates fome curious inflances of difeafed valves 
of the abforbent fyflem, and found on difleding dogs, who had 
died fome hours after he had put a ligature on the receptaculum 
chyli, that in the cellular membrane of thofe dogs, which had 
their Homachs full previous to the application of the ligature, 
much chyle was effufed on many of the vifeera, and into the 
cellular membrane conncding the laminae of the mefentery, 
and on the anterior furfaces of the pancreas, and of the kidneys ; 
part Sect. XXIX. 3.1. 
ABSORBENTS. 
243 
part of which might have efeaped from a rupture of the recep- 
taculum chyli; yet other parts of this general effufion of chyle 
muft feem to have been occafioned by their retrograde action 
in the dying hate of the animals. Medical Refearches, p. 106. 
There is a curious cafe of ifehuria related by Dr. J. Senter 
in the TranfaCtions of the College of Philadelphia, Vol. I. 1793, 
which continued more than three years, during which time, if 
the urine was not drawn off by a catheter, it was frequently void- 
ed by vomiting, and fometimes by the ficin ; which could not 
be accounted for, as Dr. Senter juftly obferves, but by fuppo- 
fing the exiftence of the retrograde action of fome parts of the 
lymphatic fyftem. 
III. Communication from the Alimentary Canal to the Bladdery by 
means of the Abforbent V ejfels. 
Many medical philofophers,both ancient and modern,have fuf- 
pefted that there was a nearer communication between the ftom- 
ach and the urinary bladder, than that of the circulation : they 
were led into this opinion from the great expedition with which 
cold water, when drunk to excefs, pafles off by the bladder ; 
and from the fimilarity of the urine, when produced in this hafly 
manner, with the material that was drunk. 
The former of thefe circumftances happens perpetually to 
thofe who drink abundance of cold water, when they arc much 
heated by exercife, and to many at the beginning of intoxication. 
Of the latter, many inftances are recorded by Etmuller, t. xi. 
p. 716. where Ample water, wine, and wine with fugar, and 
cmulfions, were returned by urine unchanged. 
There are other experiments, that feem to demonftrate the 
exiftence of another paffage to the bladder, befides that through 
the kidneys. Thus Dr. Kratzenftein put ligatures on the ure- 
ters of a dog, and then emptied the bladder by a catheter ; yet 
in a little time the deg drank greedily, and made a quantity cf 
water, (Difputat. Morbor. Halleri. t. iv. p. 63.) A Amilar ex- 
periment is related in the Philofophical Tranfaclions, with the 
fame event, (No. 65, 67, for the year 1670.) 
Add to this, that in fbme morbid cafes the urine has continu- 
ed to pafs, after the fuppuration or total deftruftion of the kid- 
neys ; of which many inftances are referred to in the Elem. 
Phy Aoi. t. vii. p. 379. of Dr. Haller. 
From all which it muft be concluded, that fome fluids have 
palled from the ftomach or abdomen, without having gone 
through the fanguiferous circulation : and as the bladder is fup- 
plied with many lymphatics, asdcfcribed by Dr. Watfon, in th« 
Phil 244 
RETROGRADE 
Sect. XXIX. 3. 1. 
Philof. Tranf. v. 59. p. 392. and as no other veffels open into it be-, 
fides thefe and the ureters, it feems evident, that the unnatural 
urine, produced as above defcribed,when the ureters were tied, or 
the kidneys obliterated, was carried into the bladder by the retro- 
grade motions of the urinary branch of the lymphatic fyftem. 
The more certainly to afcertain the exigence of another commu- 
nication between the ftomachand bladder, befidesthatof the circu- 
lation, thefollowingexperiment wasmade,towhichl muftbeg your 
patient attention :-A friend of mine ( June 14, 1772) on drink- 
ing repeatedly of cold fmall punch, till he began to be intoxica- 
ted, made a quantity of colourlefs urine. He then drank about 
two drams of nitre diflblved in fome of the punch, and ate about 
twenty italks of boiled afparagus : on continuing to drink more 
of the punch, the next urine that he made was quite clear, and 
without fmell ; but in a little time another quantity was made, 
which was not quite fo colourlefs, and had a ftrong fmell of the 
afparagus : he then loft about four ounces of blood from the arm. 
The fmell of afparagus was not at all perceptible in the blood, 
neither when freih taken, not the next morning, as myfelf and 
two others accurately attended to ; yet this fmell was ftrongly 
perceived in the urine, which was made juft before the blood 
was taken from his arm. 
Some bibulous paper, moiftened in the ferum of this blood, 
and fuffered to dry, fhewed no figns of nitre by its manner of 
burning. But fome of the fame paper, moiftened in the urine, 
and dried, on being ignited, evidently fhewed the prefence of ni- 
tre. This blood and the urine ftood fome days expofed to the 
fun in the open air, till they were evaporated to about a fourth of 
their original quantity, and began to ftink : the paper, which 
was then moiftened with the concentrated urine, fhewed the pref- 
cnce of much nitre by its manner of burning ; whilft that moif- 
tened with the blood fhewed no fuch appearance at all. 
Hence it appears, that certain fluids at the beginning of in- 
toxication, find another paffage to the bladder befides the long 
courfe of the arterial circulation ; and as the inteftinal abforb- 
ents are joined with the urinary lymphatics by frequent anafto- 
mofes, as Hewfon has demonftrated ; and as there is no other 
road, we may juftly conclude, that thefe fluids pafs into the blad- 
der by the urinary branch of the lymphatics, which has its mo- 
tions inverted during the difeafed ftate of the animal. 
A gentleman, who had been fome weeks affected with jaun- 
dice, and whofe urine was in confequence of a very deep yejlow, 
took fome cold fmall punch, in which was diflblved about a 
dram of nitre ; he then took repeated draughts of the punch, 
and kept hirnfelf in a cool room, till on the approach of flight 
intoxication Sect. XXIX. 4. 1. 
ABSORBENTS. 
245 
intoxication he made a large quantity of water ; this water had a 
fli Jit yellow tinge, as might be expected from a fmall admix- 
ture of bile fecreted from the kidneys ; but if the 'whole of it 
had palled through the fanguiferous vefl'els, which were now re- 
plete with bile (his whole fkin being as yellow as gold) would 
not this urine alfo, as well as that he had made for weeks before, 
have been of a deep yellow ? Paper dipped in this water, and 
dried, and ignited, fhewed evident marks of the prefence of ni- 
tre, when the flame was blown out. 
IV. The Phenomena of the Diabetes explained^ and of fome Diar- 
rhoeas. 
The phenomena of many difcafes are only explicable from 
the retrograde motions of fome of the branches of the lymphat- 
ic fyftem ; as the great and immediate flow of pale urine in the 
beginning of drunkennefs; in hyfteric paroxyfms ; from being 
expofed to cold air ; or to the influence of fear or anxiety. 
Before we endeavour to illuftrate this doctrine, by defcribing 
the phenomena of thefe difeafes, we muft premife one circum- 
ftance ; that all the branches of the lymphatic fyftem have a cer- 
tain fympathy with each other, infomuch that when one branch 
is ftimulated into unufual kinds or quantities of motion, fome 
other branch has its motions either increafed, or decreafed, or 
inverted at the fame time. This kind of fympathy can only be 
proved by the concurrent teftimony 'of numerous fa<Ts, which 
will be related in the courfe of the work. I (hall only add here, 
that it is probable, that this fympathy does not depend on any 
communication of nervous filaments, but on habit ; owing to 
the various branches of this fyftem having frequently been ftim- 
ulated into a&ion at the fame time. 
There are athoufand inftances of involuntarv motions aflbeiated 
in this manner ; as in the act of vomiting, while the motions of 
the ftomach and oefophagus are inverted, the pulfations of the 
arterial fyftem by a certain fympathy become weaker ; and 
when the bowels or kidneys are ftimulated by poifon, a ftone, or 
inflammation, into more violent action ; the ftomach and cefoph- 
agus by fympathy invert their motions. 
I. When any one drinks a moderate quantity of vinous fpir- 
it, the whole fyftem a<Ts with more'energy by .confent with the 
ftomach and inteftines, as is feen from the glow on the fkin, and 
the increafe of ftrength and activity ; but when a greater quan- 
tity of this inebriating material is drunk, at the fame time that 
the ladteals are excited into greater action to abforb it; it fre- 
quently happens, that the urinary branch of abforbents, which is 
connected 246 
RETROGRADE 
Sect. XXIX. 4. 2. 
connedled with the la&eals by many anaftomofes, inverts its mo- 
tions, and a great quantity of pale unanimalized urine is dif- 
charged. By this wife contrivance too much of an unnecefTary 
fluid is prevented from entering the circulation-This may be 
called the drunken diabetes, to diftinguifh it from the other tem- 
porary diabetes, which occur in hyfteric difeafes, and from con- 
tinued fear or anxiety. 
2. if this idle ingurgitation of too much vinous fpirit be dai- 
ly pradtifed, the urinary branch of abforbents at length gains a 
habit of inverting its motions, whenever the laiTeals are much 
ftimulated ; and the whole or a great part of the chyle is thus 
daily carried to the bladder without entering the circulation, and 
the body becomes emaciated,. This is one kind of chronic dia- 
betes, and may be diftinguilhed from the others by the tafte and 
appearance of the urine ; which is fweet, and of the colour of 
whey, and may be termed the chyliferous diabetes. 
3. Many children have a fimilar depofition of chyle in their 
urine, from the irritation of worms in their inteftines, which 
Simulating the mouths of the lacteals into unnatural action, the 
urinary branch of the abforbents becomes inverted, and carries 
part of the chyle to the bladder : part of the chyle alfo has been 
carried to the iliac and lumbar glands, of which inftances are 
recorded by Haller, t. vii. 225. and which can be explained on 
no other theory : but the difledlions of the lymphatic fyftem of 
the human body, which have yet been publilhed, are not fufli- 
ciently extenfive for our purpofe ; yet if we may reafon from 
comparative anatomy, this tranflation of chyle to the bladder is 
much illuftrated by the account given of this fytlem of vefTels in 
a turtle, by Mr. Hewfon, who obferved, "That the latfeals near 
the root of the mefentery anaftomofe, fo as to form a net-work, 
from which feveral large branches go into fome confiderable, 
lymphatics lying near the fpine ; and which can be traced al- 
moit to the anus, and particularly to the kidneys. Philof- 
Tranf. v. 59. p. 199-Enquiries, p. 74. 
4. At the fame time that the urinary branch of abforbents, in 
the beginning of diabetes, is excited into inverted action, the 
cellular branch is excited by the fympathy above mentioned, in- 
to more energetic adtion ; and the fat, that was before depofited, 
is reabforbed and thrown into the blood veflels ; where it floats, 
and was miftaken for chyle, till the late experiments of the inge- 
nious Mr. Hewfon demonftrated it to be fat. 
This appearance of what was miflaken for chyle in the blood, 
which was drawn from thefe patients, and the obftructed liver, 
which very frequently accompanies this difeafe, feems to have 
led Dr. Mead to fufpedt the diabetes was owing to a defeat of 
fanguification ; Sect. XXIX. 4. 5. 
ABSORBENTS. 
247 
fanguification ; and that the fcirrhofity o£ the liver was the orig- 
inal caufe of it: but as the fcirrhus of the liver is moft frequent- 
ly owing to the fame caufes, that produce the diabetes and drop- 
lies ; namely, the great ufe of fermented 1 iquors ; there is no 
wonder they fhould exift together, without being the confe- 
quence of each other. 
r. If the cutaneous branch of abforbents gains a habit of being 
excited into ftronger aft ion, and imbibes greater quantities of 
moifture from the atmofphere, at the fame time that the urina- 
ry branch has its motions inverted, another kind of diabetes is 
formed, which may be termed the aqueous diabetes. In this 
diabetes the cutaneous abforbents frequently imbibe an amazing 
quantity of atmofpheric moifture ; infomuch that there are au- 
thentic hiftories, where many gallons a day, for many weeks to- 
gether, above the quantity that has been drunk, have been dif- 
charged bv urine. 
Dr. Keil, in his Medicina Statica, found that he gained eigh- 
teen ounces from the moift air of one night; and Dr. Percival 
affirms, that one of his hands imbibed, after being well chafed, 
near an ounce and half of water, in a quarter of an hour. 
(Tranfaft. of the College, London, vol. ii. p. 102.) Home's 
Medic. Fadis, p. 2. feft. 3. 
Dr. Rollo in his work on Diabetes has (hewn, that one patient, 
whom he weighed after being ten minutes in the warm bath,- 
did not weigh heavier on his leaving it. Dr. Currie, I think, 
mentions a fimilar fact. I fufpeft, that if the bath be made very 
hot, perhaps much above animal heat, the bather may perfpire 
more than he abforbs, and become in reality lighter. And that 
in a more moderate heat, if the patient has been previoufly ex- 
haufted by abftinence or fatigue, that he will abforb much ; but 
that if his fyftem be already full of fluids, from the food and flu- 
ids, which he has previoufly eaten and drunk, he may not abforb 
anything. See Clafs I. 3. 2. 6. 
The pale urine in hyfterical women, or which is produced by 
fear or anxiety, is a temporary complaint of this kind ; and it 
would in reality be the fame difeafe, if it was confirmed by habit. 
6. The purging itools, and pale urine, occafioned by expofing 
the naked body to cold air, or fprinkling it with cold water, orig- 
inate from a fimilar caufe ; for the mouths of the cutaneous 
lymphatics being fuddenly expofed to cold become torpid, and 
ceafe, or nearly ceafe, to aft j whilfl, by the fympathy above de- 
fcribed, not only the lymphatics of the bladder and inteftines 
ceafe alfo to abforb the more aqueous and faline part of the flu- 
ids fecreted into them ; but it is probable that thefe lymphatics 
invert their motions, and return the fluids, which were previ- 
oufly 248 
RETROGRADE 
Sect. XXIX. 4. 7. 
bully abforbed, into the inteftines and bladder. At the very 
inftant that the body is expofed naked to the cold air, an unu- 
fual movement is felt in the bowels ; as is experienced by boys 
going into the cold bath: this could not occur from an obftruc- 
tion of the perfpirable matter, fince there is not time for that 
to be returned to the bowels by the courfe of the-circulation. 
There is alfo a chronic aqueous diarrhoea, in which the atmof- 
pheric moifture, drunk up by the cutaneous and pulmonary lym- 
phatics, is poured into the inteftines, by the retrograde motions 
of the ladleals. This difeafe is moft fimilar to the aqueous di- 
abetes, and is frequently exchanged for it: a diftimft inftance 
of this is recorded by Benningerus, Cent. v. Obf. 98. in which 
an aqueous diarrhoea fucceeded an aqueous diabetes, and deftroy- 
ed the patient. There is a curious example of this, defcribed by 
Sympfon (De Re Medica)-" A young man (fays he) was feiz- 
ed with a fever, upon which a diarrhoea came on, with great 
ftupor ; and he refufed to drink any thing, though he was 
parched up with exceflive heat : the better to fupply him 
with moifture, I directed his feet to be immerfed in cold water ; 
immediately I obferved a wonderful decreafe of water in the vef- 
fel, and then an impetuous ftream of a fluid, fcarcely coloured, 
was difeharged by ftool, like a cataract." 
7. There is another kind of diarrhoea, which has been called 
cceliaca ; in this difeafe the chyle, drunk up by the lafteals of 
the fmall inteftines, is probably poured into the large inteftines, 
by the retrograde motions of their lafleals : as in the chyliferous 
diabetes, the chyle is poured into the bladder, by the retrograde 
motions of the urinary branch of abforbents. 
The chyliferous diabetes, like this chyliferous diarrhoea, pro- 
duces fudden atrophy ; fince the nourilhment, which ought to 
fupply the hourly wafte of the body, is expelled by the bladder, 
cr reihum : whilft the aqueous diabetes, and the aqueous diar- 
rhoea produce exceflive thirft ; becaufe the moifture, which is 
obtained from the atmofphere, is not conveyed to the thoracic 
receptacle, as it ought to be, but to the bladder, or lower intel- 
tines ; whence the chyle, blood, and whole fyftem of glands, are 
robbed of their proportion of humidity. 
8. There is a third fpecies of diabetes, in which the urine is 
mucilaginous, and appears ropy in pouring it from one veflel 
Into another ; and will fometimes coagulate over the fire. This 
difeafe appears by intervals, and ceafes again, and feems to be 
occafioned by a previous dropfy in fome part of the body. 
When fuch a colleiTion is reabforbed, it is not always returned 
into the circulation ; but the fame irritation that ftimulates one 
lymphatic branch to ruabforb the depofited fluid, inverts the 
urinary Sect. XXIX. 4. 9. 
ABSORBENTS. 
249 
urinary branch, and pours it into the bladder. Hence this mu- 
cilaginous diabetes is a cure, or the conlequence of a cpre, of a 
worfe difeafe, rather than a difeafe itfelf. 
Dr. Cotunnius gave half an ounce of cream of tartar, every 
morning, to a patient, who had the anafarca ; and he voided a 
great quantity of urine ; a part of which, put over the fire, co- 
agulated, on the evaporation of half of it, fo as to look like the 
white of an egg. De Ifchiade Nervos. 
This kind of diabetes frequently precedes a dropfy ; and has 
this remarkable circumflance attending it, that it generally hap- 
pens in the night; as during the recumbent ftate of the body, 
the fluid, that was accumulated in the cellular membrane, or in 
the lungs, is more readily abforbed, as it is lefs impeded by its 
gravity. I have feen more than one inftance of this difeafe. 
Mr. D. a man in the decline of life, who had long accudomed 
himfelf to fpirituous liquor, had (welled legs, and other fymp- 
toms of approaching anafarca : about once in a week or ten days, 
for feveral months, he was feized, on going to bed, with great 
general uneafinefs, which his attendants refembled to an hylteric 
fit; and w'hich terminated in a great difeharge of vifeid urine ; 
his legs became lefs fwelled, and he continued in better health 
for feme days afterwards. I had not the opportunity to trv if 
this urine would coagulate over the fife, when part of it was 
evapqrated, which I imagine would be the criterion of this kind 
of diabetes ; as the mucilaginous fluid depofited in the cells and 
cyilsof the body, which have no communication with the exter- 
nal air, feems to acquire, by ftagnation, this property of coagula- 
tion by heat, which the fecreted mucus of the inteftines and blad- 
der do not appear to poffefs ; as I have found by experiment: 
and if any one (hould fuppofe this coagulable urine was fepa- 
rated from the blopd by the kidneys, he may recollect, that in the 
moft inflammatory difeafes, in which the blood is molt replete 
or molt ready to part with the coagulable lymph, none of this 
appears in the urine. 
9. Different kinds of diabetes require different methods of 
cure. For the firft kind, or chyliferous diabetes, after clearing 
the ftomach and inteftincs, by ipecacuanha and rhubarb, to 
evacuate any acid material, which may too powerfully Itimulate 
the mouths of the la&eals, repeated and large dofes of tinfture 
of cantharides have been much recommended. The fpecific 
flimulus of this medicine, on the neck of the bladder, is likely 
to excite the numerous abforbent veffels, which are fpread on 
that part, into ftronger natural attions, and by that means pre- 
vent their retrograde ones ; till, by perfilling in the ufe of the 
medicine, their natural habits of motions might again be eftab- 
Vol. I. 11 lilhed. 250 
RETROGRADE 
Sect. XXIX. 4. $ 
liffied. Another indication of cure, requires fuch medicines, as by 
lining the inteftines with mucilaginous fubftances, or with fuch as 
confilt of fmooth particles, or which chemically deftroy the acri- 
mony of their contents, may prevent the too great ablion of the 
i'nteftinal abforbents. For this purpofe, I have found the earth 
precipitated from a folution of alutn,by means of fixed alcali, given 
in rhe dofe of half a dram every fix hours, of great advantage, 
with a few grains of rhubarb, fo as to produce a daily evacuation. 
The food fhould confilt of materials that have the leait ftim- 
ulus, w'ith calcareous water, as of Briftol and Matlock; that the 
mouths of the la€teals may be as little Itimulated as is neceflary 
for their proper absorption; left with their greater exertions, 
ihould be connected by fympathy, the inverted motions of the 
urinary lymphatics. 
The fame method may be employed with equal advantage in 
the aqueous diabetes, fo great is the fympathy between the ikin 
and the ftomach. To which, however, fome application to the 
Ikin might be ufefully added ; as rubbing the patient all over 
with oil, to prevent the too great action of the cutaneous abforb- 
ents. I knew an experiment of this kind made upon one pa- 
tient with apparent advantage. 
The mucilaginous diabetes will require the fame treatment, 
which is moll efficacious in the dropfy, and will be defcribed be- 
low. I mull add, that the diet and medicines ^bove mentioned, 
are ftrongly recommended by various authors, as by Morgan, 
Willis, Harris, and Etmuller 5 but more hiilories of the fuccefsful 
treatment of thefe difeafes are wanting to fully afeertain the molt 
efficacious methods of cure. 
In a letter from Mr. Charles Darwin, dated April 24, 1778, 
Edinburgh, is the fubfequent pafiage :-" A man who had long 
laboured under a diabetes died yefterday in the clinical ward. 
He had for fome time drunk four, and palled twelve pounds of 
fluid daily : each pound of urine contained an ounce of fugar. 
lie took, without confiderable relief, gum kino, fanguis draconis 
melted with alum, tinHure of cantharides, ifmglafs, gum arabic, 
crab's eyes, fpirit of hartlhorn, and eat ten or fifteen oyllers 
thrice a day. Dr. Home, having read my thefis, bled him, and 
found that neither the freih blood nor the ferum tailed fwect. 
His bodv was opened this morning-every vifeus appeared in a 
found and natural flate, except that the left kidney had a very 
fmall pelvis, and that there was a confiderable enlargement of 
molt of the mefenteric lymphatic glands. I intend to infert this 
in my theGs, as it coincides with the experiment, where fome 
afparagus was eaten at the beginning of intoxication, and its 
fmell perceived in the urine, though not in the wlood." 
Tho Sect. XXIX. 4. 9. 
ABSORBENTS. 
251 
The following cafe of chyliferous diabetes is extracted from 
{ome letters of Mr. Hughes, to whofe unremitted care the in- 
firmary at Stafford for many years was much indebted. Dated 
October io, 1778. 
Richard Davis, aged 33, a whitefmithby trade,had drunkhard 
by intervals ; was much troubled with fweating of his hands, 
which incommoded him in his occupation, but which ceafed on 
his frequently dipping them in lime. About feven months ago 
he began to make large quantities of water ; his legs are cedem- 
atous, his belly tenfe, and he complains of a riling in his throat, 
like the globus hyftericus : he eats twice as much as other peo- 
ple, drinks about fourteen pints of fmall beer a day, befides a 
pint of ale, fome milk-porridge, and a bafon of broth, and he 
makes about eighteen pints of water a day. 
He tried alum, dragon's blood, Reel, blue vitriol, and canthar- 
ides in large quantities, and duly repeated, under the care of 
Dr. Underhill, but without any effe£t; except that on the day 
after he omitted the cantharides, he made but twelve pints of 
water, but on the next day this good effect ceafed again. 
November 21 ■-He made eighteen pints of water, and he 
now, at Dr. Darwin's requelt, took a grain of opium every four 
hours, and five grains of aloes at night 5 and had a flannel Ihirt 
given him. 
22.-Made fixteen pints. 23.-Thirteen pints : drinks lefs. 
24.-Increafed the opium to a grain and quarter every four 
hours : he made twelve pints. 
25.-Increafed the opium to a grain and half: he now makes 
ten pints; and drinks eight pints in a day. 
The opium was gradually increafed during the next fortnight, 
till he took three grains every four hours, but without any fur- 
ther dimunition of his water. During the ufe of the opium he 
fweat much in the nights, fo as to have large drops ftand on his 
face and all over him. The quantity of opium was then grad- 
ually decreafed, but not totally omitted, as he continued to take 
about a grain morning and evening. 
January 17.-He makes fourteen pints of water a day. Dr. 
Underhill now directed him two fcruplesof common refin tritu- 
rated with as much fugar, every fix hours ; and three grains of 
opium every night. 
19.-Makes fifteen pints of water : fweats at night. 
21.-Makes feventeen pints of water ; has twitchings of his 
limbs in a morning, and pains of his legs : he now takes a dram 
of refin for a dofe, and continues the opium. 
23.-Water more coloured, and reduced to fixteen pints, and 
he thinks has a brackifli tafte. 
26.-W^te? 252 
RETROGRADE 
Sect. XXIX. 4. 9. 
26.-Water reduced to fourteen pints. 
28.-Water thirteen pints : he continues the opium, and 
takes four fcruples of the refin for a dofe. 
February 1.-Water twelve pints. 
4.-Water eleven pints : twitchings lefs ; takes five fcruples 
for a dofe. 
8.-Water ten pints : has had many ftools. 
12.-Appetite lefs : purges very much. 
After this the refin either purged him, or would not ftay on 
his ftomach ; and he gradually relapfed nearly to his former 
condition, and in a few months funk under the difeafe. 
October 3, Mr. Hughes evaporated two quarts of the water, 
and obtained from it four ounces and half of a hard and brittle 
faccharine mafs, like treacle which had been feme time boiled. 
Four ounces of blood, which he took from his arm with defign 
to examine it, had, the common appearances, except that the fe- 
rum refembled cheefe-whey ; and that on the evidence of four 
perfons, two of whom did not know what it was they tailed, the 
ferum had a faltijb tajh. 
From hence it appears, that the faccharine matter, with which 
the urine of thefe patients fo much abounds, decs not enter the 
blood-veffels like the nitre and afparagus mentioned above ; but 
that the procefs of digeilion refembles the procefs of the ger- 
mination of vegetables, or of making barley into malt; as the 
vaft quantity of fugar found in the urine mail be made from 
the food which he took (which was double that taken by others), 
and from the fourteen pints of fmall beer which he drank. And, 
fecondly, as the ferum of the blood was not fweet, the chyle ap- 
pears to have been conveyed to the bladder without entering the 
circulation of the blood, fince fo large a quantity of fugar, as 
was found in the urine, namely, twenty ounces a day, could not 
have previoully exifted in the blood without being perceptible to 
the tafte. 
November 1. Mr. Hughes diflblved two drams of nitre in a 
pint of a decoction of the roots of afparagus, and added to it two 
ounces of tincture of rhubarb : the patient took a fourth part 
of this mixture every five minutes, till he had taken the whole. 
-In about half an hour he made eighteen ounces of water, 
which was very manifeflly tinged with the rhubarb ; the finell 
of afparagus was doubtful. 
He then loft four ounces of blood, the ferum of which was 
not fo opaque as that drawn before, but of a yellowifh call, as 
the ferum of the blood ufually appears. 
Paper, dipped three or four times in the tinged urine and dri- 
ed again, did not fcintillatc when it was let on fire ; but when 
the Sect. XXIX. 5. 1. 
ABSORBENTS. 
253 
the flame was blown out, the fire ran along the paper for half an 
inch ; which, when the lame paper was unimpregnated, it 
would not do ; nor when the fame paper was dipped in urine 
jnade before he took the nitre, and dried in the fame manner. 
Paper, dipped in the ferum of the blood and dried in tl;e fame 
manner as in the urine, did not fcintillate when the flame was 
blown cut, but burnt exactly in the fame manner as the fame 
paper dipped in the femm of blood drawn from another perfon. 
This experiment, which is copied from a letter of Mr. Hughes, 
as well as the former, feems to evince the exiflence of another 
paflage from the inteftinesto the bladder, in this difeafe, befides 
that of the fanguiferous fyfiem ; and coincides with the curious 
experiment related in feclion the third, except that the fmell of 
the afparagus was not here perceived, owing perhaps to the 
roots having been made ufe of inftead of the heads. 
The rifing in the throat of this patient, and the twitchings of 
his limbs, feem to indicate fome fimilarity between the diabetes 
and the hyfleric difeafe, befides the great flow of pale urine, 
which is con^mon to them both. 
Perhaps if the mefcnteric glands were nicely infpeefted in the 
difledions of thefe patients ; and if the thoracic duct, and the 
larger branches of the ladeals, and if the lymphatics, which 
arife from the bladder, were well examined bv injection, -or by 
the knife, the caufe of diabetes might be more certainly under- 
ftood. 
The opium alone, and the opium with the refin, feem much 
to have ferved this patient, and might probably have effected a 
cure, if the difeafe bad been {lighter, or the medicine had been 
exhibited, before it had been confirmed by habit during the fev- 
cn months it had continued. The increafe of the quantity of 
water on beginning the large dofes of refin was probably owing 
to his omitting the morning dofes of opium. 
As the urine in chyliferous diabetes abounds fo much with 
faccharine matter, as appears from the above cafe of Davis, Dr. 
Rollo has ingeniously recommended a diet of animal food alone ; 
this, with a diminution of the quantity of fluid, which the pa- 
tient was previoufly atcuftomed to, is find to have changed the 
quality of the urine, and to have diminilhed its quantity. See 
Part IL Clafs I. 3. 2. 6. of this work. 
V. 27>? Phenomena cj Dropfies explained. 
I. Some inebriates have their paroxyfms of inebriety termin- 
ated by much pale urine, or profufe fweats, or vomiting, or 
ftools 5 254 
RETROGRADE 
Sect. XXIX. 5. 1. 
llools ; others have their paroxyfms terminated by ftupor, or 
■fleep, without the above evacuations. 
The former kind of thefe inebriates have been obferved to be 
more liable to diabetes and dropfy ; and the latter to gout, 
gravel, and leprofy. Evoe ! attend ye bacchanalians I ftrrt at 
this dark train of evils, and amid your immodeft jefts, and idiot 
laughter, recollect, 
Quem Deus vuit perdere, prius dementat. 
In thofe who are fiibjeft to diabetes and dropfy, the abforbent 
veflels are naturally more irritable than in the latter ; and by be- 
ing frequently difturbed or inverted by violent ftimulus, and by 
their too great fympathy with each other, they become at length 
either entirely paralytic, or are only fufceptible of motion from 
the ftimulus of very acrid materials ", as every part of the body, 
after having been ufed to great irritations, becomes lefs afleCted 
by fmaller ones. Thus we cannqt diftinguilh objects in the 
night, for feme time after we come out of a ftrong light, though 
the iris is prefently dilated ; and the air of a fummer evening 
appears cold, after we have been expofed to the heat of the day. 
There are no cells in the body, where dropfy may not be pro- 
duced, if the lymphatics ceafe to abforb that mucilaginous fluid, 
which is perpetually depofitpd in them, for the purpofe of lubri- 
cating their furfaces. 
If the lyrnphatic branch, which opens into the cellular mem- 
brane, either does its office imperfectly, or not all; thefe cells 
become replete with a mucilaginous fluid, which, after it has 
ftagnated fome time in the cells, will coagulate over the fire ; 
and is erroneoufly called water. Wherever the feat of this dif- 
eafe is, (unlefs in the lungs or other pendent vifeera) the mucilag- 
inous liquid above mentioned will fubfide to the molt depend- 
ing parts of the body, as the feet and legs, when thofe are lower 
than the head and trunk j for all thefe cells have communica- 
tions with each other. 
When the cellular abforbents are become infenfible to their 
ufual irritations, it moft frequently happens, but not always, 
that the cutaneous branch of abforbents, which is ftriCtly aflbei- 
ated with them, fullers the like inability. And then, as no wa- 
ter is abforbed from the atmofpherc, the urine is not only lefs 
diluted at the time of its fecretion, and confequently in lefs 
quantity and higher coloured : but great thirft is at the fame 
time induced, for as no water is abforbed from the atmofphere 
to dilute the chyle and blood, the laCleals and other abforbent 
veflels, which have not loft their powers, are excited into more 
eonftant or more violent action, to fupplv this deficiency ; 
whence Sect. ZXIX 5. 1. 
ABSORBENTS. 
255 
whence the urine becomes dill lefs in quantity, and of a deeper 
colour, and turbid like the yolk of an egg, owing to a greater ab- 
iorption of its thinner parts. From this ftronger action of thofe 
abforbents, which ftiil retain their irritability, the fat is alfo ab-' 
forbed, and the whole body becomes emaciated. This increafed 
exertion of fome branches of the lymphatics, while others aie 
totally or partially paralytic, is refembled by what conftantly oc- 
curs in the hemiplegia ; when the patient has loft the ufe of the 
limbs on one fide, lie is inceffantly moving thofe of the other j 
for the moving power, not having accefs to the paralytic limbs, 
becomes redundant in thofe which are not difeafed. 
The paucity of urine and thirft cannot be explained from a 
greater quantity of mucilaginous fluid being depoiited in the 
cellular membrane : for though thefe fymptoms have continued 
many weeks, or even months, this coiledlion frequently d.oes 
not amount to more than very few pints. Hence aifo the dif- 
ficulty of promoting copious fweats in anafarca is accounted for, 
as well as the great thirft, paucity of urine, and lofs of fat; fince, 
■when the cutaneous branch of abforbents is paralytic, or nearly 
fo, there is already too fmall a quantity of aqueous fluid in the 
blood : nor can thefe torpid cutaneous lymphatics be readily ex- 
cited into retrograde motions. 
Hence likewife we underftand, why in the afeites, and fome 
other dropfies, there is often no thirft, and no paucity of urine ; 
in thefe cafes the cutaneous abforbents continue to do their oilice. 
Some have believed, that dropfies were occafioned by the in- 
ability of the kidneys, from having only obferved the paucity of 
urine ; and have thence laboured much to obtain diuretic medi- 
cines ; but it is daily obfervable, that thofe who die of a total itiJ 
ability to make water, do not become dropfical in confequence 
of it: Fernelius mentions one, who laboured under a perfect fup- 
preflion of urine during twenty days before his death, and yet 
had no fymptoms of dropfy. Pathol. 1. vi. c. 8. From the 
fame idea many phyficians have reftrained their patients from 
drinking, though their thirft has been very urgent; and fome 
cafes have been publilhed, where this cruel regimen has been 
thought advantageous : but others of nicer obfervation are of 
opinion, that it has always aggravated the diftrefles of the patient; 
and though it has abated his fwcllings, yet by inducing afever it 
has haftened his diflTolution. See Tranfadtions of the College, 
London, vol. ii. p. 235. Cafes of Dropfy by Dr. G. Baker. 
The cure of anafarca, fo far as refpedts the evacuation of the 
accumulated fluid, coincides with the idea of the retrograde ac- 
tion of the lymphatic fyftem. It is well known that vomits, and 
ether drugs, which induce ficknefs or naufea, at the lame time 
that 256 
RETROGRADE 
Sect. XXIX. 5. 2<- 
that they evacuate the ftomach, produce a great abforption of 
the lymph accumulated in the cellular membrane. In the op- 
eration of a vomit, not only the motions of the ftomach and du- 
odenum become inverted, but alfo thofe of the lymphatics and, 
la&eals, which belong to them ; whence a great quantity of 
chyle and lymph is perpetually poured into the ftomach and in- 
teftines, during the operation, and evacuated by the mouth. 
Now at the fame time, other branches of the lymphatic fyftem, 
viz. thofe which open on the cellular membrane, are brought in- 
to more energetic aflion, by the fympathy above mentioned, and 
an increafe of their abforption is produced. 
Hence repeated vomits, and cupreous faits, and fmall dofes of 
fquill or foxglove, are fo efficacious in this difeafe. And as draf- 
tic purges aft alfo by inverting the motions of the lafteals ; and 
thence the other branches of lymphatics are induced into more 
powerful natural aflion, by fympathy, and drink up the fluids 
from all the cells of the body ; and by their anaftomofes, pour 
them into the ladteal branches ; which, by their inverted actions, 
return them into the inteftines ; and they are thus evacua- 
ted from the body :-thefe purges alfo are ufed with fuccefs in 
difeharging the accumulated fluid in anafarca. 
II. The following cafes are related with defign to afeertain 
the particular kinds of dropfy in which the digitalis purpurea, or 
common foxglove, is preferable to fquill, or other evacuants, 
and were firft publifhed in 1780, in a pamphlet entitled Exper- 
iments on mucilaginous and purulent Matter, &c. Cadell. Lon- 
don. Other cafes of dropfy, treated with digitalis, were after- 
wards publifhed by Dr. Darwin in the Medical Tranfafiions, 
vol. hi. in which there is a miftake in refpecl to the dole of the 
powder of foxglove, which fhould have been from five grains to 
one, in dead of from five grains to ten. 
.Anafarca of the Lungs. 
i. A lady, between forty and fifty years of age, had been in- 
difpofed fomc time, was then feized with cough and fever, and 
afterwards expectorated much digefted mucus. This expecto- 
ration fuddenly ceafed, and a confiderable difficulty of breathing 
fupervened, with a pulfe very irregular both in velocity and 
ftrength; ihe was much diftrcffed at fir ft lying down, and at 
fir ft nfing ; but after a minute or two bore either of thofe attitudes 
with eafe. She had no pain or numbnefs in her arms; fhe had 
no hectic fever, nor any cold fhiverings, and the urine was in 
due quantity, and of the natural colour. 
The difficulty of breathing was twice confiderably relieved by 
imaH Sect. XXIX. 5. 2. 
ABSORBENTS. 
257 
fmall dofes of ipecacuanha, which operated upwards and down- 
wards, but recurred in a few days : ffie was then directed a de- 
coction of foxglove, (digitalis purpurea) prepared by boiling four 
ounces of the freffi leaves from two pints of water to one pint; 
to which werd added two ounces of vinous fpirit: ffie took three 
large fpoonfuls of this mixture every two hours, till ffie had 
taken it four times ; a continued ficknefs fupervened, with fre- 
quent vomiting, and a copious flow of urine: thefe evacuations 
continued at intervals for two or three days, and relieved the 
difficulty of breathing.-She had fome relapfes afterwards, which 
were again relieved by the repetition of the decodlion of foxglove. 
2. A gentleman, about fixty years of age, who had been ad- 
dicted to an immoderate ufe of fermented liquors, and had been 
very corpulent, gradually loft his ftrength and flelh, had great 
difficulty of breathing, with legs fomewhat fwclled, and a very 
irregular pulfe. He was very much diftrefled at lirft lying down, 
and at firft riling from his bed, yet in a minute or two was eafy 
in both thefe attitudes. He made ftraw-coloured urine in due 
quantity, and had no pain or numbnefs of his arms. 
He took a large fpoonful of the deception of foxglove, as above, 
every , hour, for ten or twelve fucceffive hours, had inceffiant fick- 
nefs for about two days, and palled a large quantity of urine; 
upon wffiich his breath became quite eafy, and the fwelling of 
his legs fubfided ; but as his whole conftitution was already link- 
ing from the previous intemperance of his life, he did not fur- 
vive more than three or four months. 
Hydrops Pericardii. 
3. A gentleman of temperate life and fedulo'us application to 
bulinefs, between thirty and forty years of age, had long been 
fubjeft, at intervals, to an irregular pulfe ; a few months ago he 
became weak, with difficulty of breathing, and dry cough. In 
this fituation a phyfician of eminence directed him to abftain from 
ail animal food and fermented liquor, during which regimen ail 
his complaints increafed ; he now became emaciated, ami total- 
ly loft his appetite ; his pulfe very irregular both in velocity and 
ftrength ; with great difficulty of breathing, and fofne fu elling 
of his legs ; yet he could he down horizontally in his bed, though, 
he got little fleep, and palled a due quantity of urine, and of the 
ziatural colour : no fullnefs or hardnefs could be perceived about 
the region of the liver ; and he had no pain or numbnefs in his 
arms. 
One night he h^d a moft profufe fweat all over his body and 
limbs, which quite deluged his bed, and for a day or two fome- 
Vol. I. K k what 258 
RETROGRADE 
Sect. XXIX 5. xJ 
what relieved his difficulty of breathing, and his pulfe became 
lefs irregular: this copious fweat recurred three or four times at 
the intervals of five or fix days, and repeatedly alleviated his- 
fymptoms. 
He was direfled one large fpoonful of the above decoflion of 
foxglove every hour, till it procured fome confiderable evacua- 
tion : after he had taken it eleven fucceffive hours he had a 
few liquid ftools, attended with a great flow of urine, which laft 
had a dark tinge, as if mixed with a few drops of blood : he 
continued fick at intervals for two days, but. his breath became 
quite eafy, and his pulfe quite regular, the fwelling of his legs 
difappeared, and his appetite and fleep returned. 
He then took three grains of white vitriol twice a day, with 
fome bitter medicines, and a grain of opium with five grains of 
rhubarb every night; was advifed to eat flelh meat, and fpice, 
as his ftomach would bear it, with fmall beer, and a few glafles 
of wine ; and had ifiues made in his thighs ; and has fullered, 
no relapfe. 
4. A lady, about fifty years of age, had for fome weeks great 
difficulty of breathing, with very irregular pulfe, and confidera- 
ble general debility: (he could lie down in bed, and the urine 
was in due quantity and of the natural colour, and (he had no 
pain or numbnefs of her arms. 
She took one large fpoonful of the above decoflion of foxglove 
every hour, for ten or twelve fucceffive hours-, was fick, and 
made a quantity of pale urine for about two days, and was quite 
relieved both of the difficulty of breathing, and the irregularity 
of her pulfe. She then took a grain of opium, and five grains 
of rhubarb, every night, for many weeks ; with fome flight cha- 
lybeate and bitter medicines, and has fuffered no relapfe. 
Hydrops Thoracis. 
5. A tradefman, about fifty years of age, became weak and 
fhort of breath, efpecially on increafe of motion, with pain in 
one arm, about the infertion of the biceps mufcle. He obferv- 
ed he fometimes in the night made an unufual quantity of pale- 
water. He took calomel, alum, and peruvian bark, and all his 
fymptoms increased : his legs began to fwell confiderably ; his 
breath became more difficult, and he could not lie down in bed; 
but all this time he made a due quantity of ftraw-coloured 
water. 
The decotdion of foxglove was given as in the preceding ca- 
fes, which operated chiefly by purging, and feemed to relieve 
his breath for a day or two ; but allo teemed to contribute to 
weaken Sect. XXIX. 5. 2. 
ABSORBENTS. 
259 
weaken him.-He became after fomc weeks univerfally dropflcal, 
and died comatofe. 
6. A young lady of delicate conftitution, with light eyes and 
hair, and who had perhaps lived too abftcmioufly both in refpect 
to the quantity and quality of what (lie ate and drank, was feiz- 
ed with great diflaculty of breathing, fo as to threaten immedi- 
,ate death. Her extremities were quite cold, and her breath felt 
cold to the back of one's hand. She had no fweat, nor could 
lie down for a fingle moment; and had previoufly, and at pref- 
ent, complained of great weaknefs and pain and numbnefs of 
both her arms ; had no fwelling of her legs, no thirft, water in 
due quantity and colour. Her fifter, about a year before, was 
aflliCled with fimilar fymptoms, was repeatedly blooded, and di- 
ed univerfally dropfical. 
A grain of opium was given immediately, and repeated every 
fix hours with evident and amazing advantage ; afterwards a 
biifter, with chalybeates, bitters,-and eflential oils, were exhibit- 
ed, but nothing had fuch eminent efleCt in relieving the difficul- 
ty of breathing and coldnefs of her extremities as opium, by 
the ufe of which in a few weeks (he perfectly regained her 
iiealth, and Iras fullered no relapfe. 
Afcrtes. 
A young lady of delicate conftitution having been expo- 
■fed to great fear, cold, and fatigue, by the overturn of a chaife 
in the night, began with pain and tumour in the right hypo- 
chondrium : in a few months a fluctuation was felt throughout 
the whole abdomen, more diftinCtly perceptible indeed about the 
region of the ftomach ; fince the integuments of the lowet part 
of the abdomen generally become thickened in this difeafe by a 
degree of anafarca. Her legs were not fwelled, no thirft, water 
in due quantity and colour.-She took the foxglove fo as to in- 
duce ficknefs and (tools, but without abating the fwelling, and 
was obliged at length to fubmit to the operation of tapping. 
8. A man about fixty-feveu, who had long been accuftomed 
to fpirituous potation, had fome time laboured under afcites ; 
his legs fomewhat fwelled ; his breath eafy in all attitudes ; no 
appetite ; great thirft ; urine in exceedingly fmall quantity, very 
deep coloured, and turbid ; pulfe equal. He took the foxglove 
in fuch quantity as vomited him, and induced ficknefs for two 
days ; but procured no flow of urine, or diminution of his fweli- 
ing j but was thought to leave him confiderably weaker. 
9. A corpulent man, accuftomed to a large potation of fer- 
mented liquors, had vehement cough, difficult breathing, ana- 
farca 260 
RETROGRADE 
Sect. XXIX. 5. 2. 
farca of his legs, thighs, and hands, and confiderable tumour, 
with evident fluctuation of his abdomen ; his pulfe was equal; 
his urine in fmall quantity, of deep colour, and turbid. Theft 
fwellings had been twice confiderably abated by draftic cathar- 
tics. He took three ounces of a decoction of foxglove (made 
by boiling one ounce of the frefli leaves in a pint of water) every 
three hours, for two whole days ; it then began to vomit and 
purge him violently, and promoted a great flow of urine; he 
was by thefe evacuations completely emptied in twelve hours. 
After two or three months all thefe fymptoms returned, and 
were again relieved by the ufe of the foxglove ; and thus in the 
fpace of about three years he was about ten times evacuated, 
and continued all that time his ufual potations : excepting at 
firft, the medicine operated only by urine, and did not appear 
confiderably to weaken him.-The Lift time he took it, it had 
no effeCt; and a few weeks afterwards he vomited a great quan- 
tity of blood, and expired. 
QJJ ERIES. 
i. As the firfl: fix of thcfe patients had a due difcharge of 
urine, and of the natural colour, was not the feat of the difeafe 
confined to fome part of the thorax, and the fwelling of the legs 
rather a fymptom of the obftructed circulation of the blood, 
than of a paralyfis of the cellular lymphatics of thofe parts ? 
2. When the original difeafe is a general anafarca, do not the 
cutaneous lymphatics always become paralytic at the fame time 
with the cellular ones, by their greater fympathy with each oth- 
er ? and hence the paucity of urine, and the great thirft, diftin- 
guifn this kind of dropfy ? 
3. In the anafarca of the lungs, when the difeafe is not very 
great, though the patients have confiderable difficulty of breath- 
ing at their firft lying down, yet after a minute or two their 
breath becomes eafy again ; and the fame occurs at their firft 
rifing. Is not this owing to the time neceflary for the fluid in 
the cells of the lungs to change its place, fo as the leaft to incom- 
mode refpiration in the new attitude ? 
4. In the dropfy of the pericardium does not the patient bear 
the horizontal or perpendicular attitude with equal eafe ? Does 
this circumftance diftinguiffi the dropfy of the pericardium from 
that of the lungs and of the thorax ? 
5. Do the univerfal fweats diftinguifh the dropfy of the peri- 
cardium, or of the thorax ? and thofe, which cover the upper 
parts of the body only, the anafarea of the lungs ? 
6. When in the dropfy of the thorax, the patient endeavour^; 
to Sect. XXIX. 5. 2. 
ABSORBENTS. 
261 
to lie down, does not the extravafated fluid com prefs the upper 
parts of the bronchia, and totally preclude the accefs of air to 
every part of the lungs ; whilft in the perpendicular attitude the 
inferior parts of the lungs only are comprefled ? Does not fomc- 
thing fimilar to this occur in the anaiarca of the lungs, when 
die difeafe is very great, and thus prevent thofe patients alfo 
from lying down ? 
7. As a principal branch of the fourth cervical nerve of the 
left fide, after having joined a branch of the third and of the fec- 
ond cervical nerves, defcending between the fubclavian vein and 
artery, is received in a groove formed fdr it in the pericardium, 
and is obliged to make a confiderable turn outwards to go over 
the prominent part of it, where the point of the heart is lodged, 
in its courfe to the diaphragm ; and as the other phrenic nerve 
of the right fide has a ftraight courfe to the diaphragm ; and as 
many other confiderable branches of this fourth pair of cervical 
nerves are fpread on the arms 5 does not a pain in the left arm 
diftinguifh a difeafe of the pericardium, as in the angina pefto- 
ris, or in the dropfy of the pericardium ? and does not a pain 
or weaknefs in both arms diftinguifh the dropfy of the thorax ? 
8. Do not the dropfies cf the thorax and pericardium fre- 
quently exift together, and thus add to the uncertainty and fa- 
tality of the difeafe ? 
9. Might not the foxglove be ferviceable in hydrocephalus in- 
ternus, in hydrocele, and in white fwellings of the joints ? 
VI. Of cold Sweats. 
There have been hiftories given of chronical immoderate 
Sweatings, which bear fome analogy to the diabetes. Dr. Willis 
mentions a lady then living, whofe fweats were for many years 
fo profufe, that all her bed-clothes were not only moiftened, 
bgt deluged with them every night; and that many ounces, and 
fornetimes pints, of this fweat, were received in vefle^s properly 
placed,'as it trickled down her body. He adds, that Ihe had 
great thirft, had taken many medicines, and fubmitted to various 
rules of* life, and changes of climate, but ftill continued to have 
thefe immoderate fweats. Pharmac. ration, de fudore anglico. 
Dr. Willis has alfo obferved, that the fudor anglicanus which 
appeared in England, in 1483, and continued till 1551, was in 
fome refpe&s fimilar to the diabetes; and as Dr. Caius, who 
faw this difeafe, mentions the vifcidity, as well as the quantity 
of thefe fweats, and adds, that th§ extremities were often cold, 
when the internal parts were burnt up with heat and thirft, 
with great and fpeedy emaciation and debility : there is great 
reafun 262 
RETROGRADE 
Sect. XXIX. 6. 
teafon to believe, that the fluids were abforbed from the cells of 
the body by the cellular and cyftic branches of the lymphatics, 
and poured on the Ikin by the retrograde motions of the cuta- 
neous ones. 
Sydemiam has recorded, in the ftationary fever of the year 
z68^, the vifeid fweats flowing from the head, which were prob- 
ably from the fame fource as thofe in the fweating plague above 
mentioned. 
It is very common in dropfies of the cheft or lungs to have 
the difficulty of breathing relieved by copious fweats, flowing 
from the head and neck. Mr. P. about fifty years of age, had 
for many weeks been afflicted V Uh anafarca of his logs and thighs, 
attended with difficulty of breathing ; and had repeatedly been 
relieved by fquill, other bitters, and chalybeates.-One night 
the difficulty of breathing became fo great, that it was thought 
he muff have expired ; bet fo copious a fweat came out of his 
head and neck, that in a few hours fome pints, by eftimation, 
were wiped off from thofe parts, and his breath was for a time 
relieved. This dvfpnoea and thefe fweats recurred at intervals, 
and after fome weeks he ceafed to exift. The fkin of his head 
and neck felt cold to the hand, and appeared pale at the time thefe 
fweats flowed fo abundantly ; which is a proof, that they were 
produced by an inverted motion of the abforbents of thofe parts : 
fpr fweats, which are the confequence of an increafed action of 
the fangujferous fyltem, are always attended with a warmth of 
the fkin, greater than is natural, and a more florid colour; as 
the fweats from exercife, or thofe that fucceed the cold fits of 
agues. Can any one explain how thefe partial fweats fhould re- 
lieve the difficulty of breathing in anafarca, but by fuppofing that 
the pulmonary branch of abforbents drank up the fluid in the 
cavity of the thorax, or in the cells of the lungs, and threw it on 
the fkin, by the retrograde motions of the cutaneous branch ? 
for, if we could fuppofe, that the increafed action of the cuta- 
neous glands or capillaries poured upon the fkin this fluid, pre- 
vioufly abforbed from the lungs ; why is not the whole furface of 
the body covered with fweat ? why is not the fkin warm ? Add 
to this, that the fweats above mentioned were clammy or gluti- 
nous, which the condenfed perfpirable matter is not; whence it 
would feem to have been a different fluid from that of common 
perfpiration. 
Dr. Dobfon, of Liverpool, has given a very ingenious expla- 
nation of the acid fweats, wffiich he obferved in a diabetic patient 
-he thinks part of the chyle is fecreted by the ikin, and after- 
wards undergoes an acetous fermentation.-Can the chyle get 
thither, but by an inverted motion of the cutaneous lymphatics ? 
in Sect. XXIX. 7. 1. 
ABSORBENTS. 
263 
in the fame manner as it is carried to the bladder, by the inverted 
motions of the urinary lymphatics. Medic. Obfervat. and 
Enq. London, voJ.v. 
Are not the cold fweats in fome fainting fits, and in dying 
people, owing to an inverted motion of the cutaneous lymphat- 
ics ? for in thefe there can be no increafed arterial or glandular 
a (flion. 
Is the difficulty of breathing, arifing from anafarca of the lungs, 
relieved by fweats from the head and neck.; whilft that difficul- 
ty of breathing, which arifes from a dropfy of the thorax, or peri- 
cardium, is never attended with thefe fweats of the head ? and 
thence can thefe difeafes be diftinguifhed from each other ? Do 
the periodic returns of nocturnal althma rife from a temporary 
dropfy of the lungs, collected during their more torpid ftate in 
found fleep, and then re-abforbed by the vehement efforts of the 
difordered organs of refpitation, and carried off by the copious 
fweats about the head and neck ? 
More extenfive and accurate diffeffions of the lymphatic fyf- 
tem are wanting to enable us to unravel thefe knots of fcience. 
VIL Tranflations of Matter, of Chyle, of Milk, of Urine. Oper* 
ation of purging Drugs applied externally. 
i. The tranflations of matter from one part of the body to 
another, can only receivfe an explanation from the doctrine of 
the occafional retrograde motions of fome branches of the lymph- 
atic fyftcm : for how can matter, abforbed and mixed with the 
whole mafs of blood, be fo haftily collected again in any oile 
part ? and is it not an immutable law, in animal bodies, that 
each gland can fecrete no other, but its own proper lluid ? which 
is, in part, fabricated in the very gland by an animal procefs, 
which it there undergoes: of thefe purulent tranflations innu- 
merable and very remarkable inltances are recorded. 
2. The chyle, which is feen among the materials thrown up 
by violent vomiting, or in purging ftools, can only come thither 
by its having been poured into the bowels by the inverted mo- 
tions of the lacteals : for our aliment is not converted into chyle 
in the ftomach or inteltines by a chemical procefs, but is made 
in the very mouths of the ladteals ; or in the mefenteric glands; 
in the fame manner as other fecreted fluids are made by an ani- 
mal procefs in their adapted glands. 
Here a curious phrenomenon in the exhibition of mercury is 
worth explaining :-If a moderate dofe of calomel, as fix or ten 
grains, be fwallowad, and within one or two days a cathartic is 
given, a falivation is prevented : but after three or four days, a 
falivation 264 
RETROGRADE 
Sect. XXIX. 7. 3-. 
falivation having come on, repeated purges every day, for a week 
or two, are required to eliminate the mercury from the conftitu- 
tion. For this acrid metallic preparation, being abforbed by the 
mouths of the ladleals, continues, for a time arrefted by the mef- 
enteric glands, (as the variolous or venereal poifons fwell the 
fubaxillar or inguinal glands): and, during the operation of a 
cathartic, is returned into the inteftines by the inverted action 
of the ladteals, and thus carried out of the fyftem. 
Hence we understand the ufe of vomits or purges, to thofe 
who have fwallowed either contagious or poifonous materials, 
even though exhibited a day or even two days after fuch acci- 
dents ; namely, that by the retrograde motions of the Jafteals 
and lymphatics, the material Hill arrefted in the mefenteric, or 
other glands, may be eliminated from the body. 
3. Many inftances of milk and chyle found in ulcers are giv- 
en by Haller, El. Phyfiol. t. vii. p. 12, 23, which admit of no 
other explanation than by fuppofmg, that the chyle, imbibed by 
one branch of the abforbent fyftem, was carried to the ulcer, by 
the inverted motions of another branch of the fame fyftem. 
4. Mrs. P. on the fecond day after delivery, was feized with 
a violent purging, in which, though opiates mucilages, the bark, 
and teftacea were profufely ufed, continued many days, till at 
length (he recovered. During the time of this purging, no milk 
could be drawn from her breafts ; but the ftools appeared like 
the curd of milk broken into fmall pieces. In this cafe, was not 
the milk taken up from the follicles of the pectoral glands, and 
thrown on the inteftines, by a retrogrelhon of the inteftinal ab- 
forbents ? for how can we for a moment fufpect that the mucous 
glands of the inteftines could feparate pure milk from the blood ? 
Dr. Smellie has obferved, that loofe ftools, mixed with milk, 
which is curdled in the inteftines, frequently relieves the tur- 
gefcency of the breafts of thofe who ftudioufly repel their milk. 
Cafes in Midwifery, 43, No. 2. I. 
5. J. F. Meckel obferved in a patient, whofe urine was in fmall 
quantity and high coloured, that a copious fweat under the arm- 
pits, of a perfectly urinous fmell, ftained the linen ; which ceaf- 
ed again when the ufual quantity of urine was difeharged by the 
urethra. Here we mu ft believe from analogy, that the urine 
was fnft fecreted in the kidneys, then re-abforbed by theincreaf- 
ed ailion of the urinary lymphatics, and laftly carried to the ax- 
illoe by the retrograde motions of the lymphatic branches of 
thofe parts. As in the jaundice it is neceifary, that the bile 
fhould firft be fecreted by the liver, and re-abforbed into the cir- 
culation, to produce the yellownefs of the Ikin ; as was form- 
erly demonftrated by the late Dr. Munro, (Edin. Medical Ef- 
fays) Sect. XXIX. 7. 6. 
ABSORBENTS. 
265 
fays) and if in this patient the urine had been reabforbed into 
the mafs of blood, as the bile in the jaundice, why was it not de- 
tedled in other parts of the body, as well as in the arm-pits ? 
6. Cathartic and vermifuge medicines applied externally to 
the abdomen, feem to be taken up by the cutaneous branch of 
lymphatics, and poured on the inteftines by the retrograde mo- 
tions of the latleals, without having pafled the circulation. 
For when the draftic purges are taken by the mouth, they ex- 
cite the Lufteals of the inteftines into retrograde motions, as ap- 
pears from the chyle, which is found coagulated among the fae- 
ces, as was fhewn above, ^fecl. 2 and 4.) And as the cutaneous 
lymphatics are joined with the ladteals of the inteftines, by fre- 
quent anaftomofes ; it would be more extraordinary, when a 
ftrong purging drug, abforbed by the fkin, is carried to the anaf- 
tomofing branches of the lafdeals unchanged, if it fhould not 
excite them into retrograde action as efficacioufly, as if it was 
taken by the mouth, and mixed with the food of the ftomach. 
VIII. Circumfances by •which the Fluids^ that arc ejfufed by the 
Retrograde Motions of the Abforbent Ffelsi are dfinguijhed. 
t. We frequently obferve an unfual quantity of mucus or 
Other fluids in fome difeafes, although the action of the glands, 
by which thofe fluids are feparated from the blood, is not un- 
ufually increafed j b.ut when the power of abforption alone is di- 
minifhed. Thus the catarrhal humour from the noltrils of 
fome, w'ho ride in frofty weather ; and the tears, which run 
dow'ii the cheeks of thofe, who have an obftrutlion of the punc- 
ta lacrymalia ; and the ichor of thofe phagedenic ulcers, which 
are not attended with inflammation, arc all inftances of this cir- 
cum'tance. 
Thefe fluids however are eafily diltinguifhed from others by 
their abounding in ammbniacal or muriatic faits ; whence they 
inflame the circumjacent ikin : thus in the catarrh the upper lip 
becomes red and fwelled from the acrimony of the mucus, and. 
patients complain of jhe faltnefs of its taife. The eyes and 
Cheeks are red with the corrofive tears, and the ichor of fome 
herpetic eruptions erodes far and wide the contiguous parts, and 
is pungently fait to the tafte, as fome patients have informed me. 
Whilft, on the contrary, thofe fluids, which are effufed by 
the retrograde action of the lymphatics, are for the moft part 
mild and innocent ; as water, chyle, and the natural mucus : 
or they take their properties from the materials previoufly ab- 
forbed, as in the coloured or vinous urine, or that feented with 
afparagus, defer!bed before. ' 
Vol. I. L l 2. Whenever 266 
RETROGRADE 
Sect. XXIX. 8. 
2. Whenever the fecretion of any fluid is increafed, there is 
at the fame time an increafed heat in the part; for the fecreted 
fluid, as the bile, did not previoufly exift in the mafs of blood, 
but a new combination is produced in the glands Now^s folu- 
tions are attended with cold, fo combinations are attended with 
heat ; and it is probable the fum of the heat given out by all the 
fecreted fluids of animal bodies may be the caufe of their gen- 
eral heat above that of the atmofphere. 
Hence the fluids derived from increafed fecretions are read- 
ily diftinguifhed from thofe originating from the retrograde mo- 
tions of the lymphatics : thus an increafe of heat either in the 
difeafed parts, or diflufed over the whole body, is perceptible, 
when copious bilious flools are confequent to an inflamed liver ; 
or a copious mucous falivation from the inflammatory angina. 
3. When any fecreted fluid is produced in an unufual quanti- 
ty, and at the fame time the power of abforption is increafed in 
equal proportion, not only the heat of the gland becomes more 
intenfe, but the fecreted fluid becomes thicker and miider, its 
thinner and faline parts being re-abforbed : and thefe are dif- 
tinguifhable both by their greater confiftence, and by their heat, 
from the fluids, which are effufed by the retrograde motions of 
the lymphatics ; as is'obfervable towards the termination of gon- 
orrhoea, catarrh, chincough, and in thofe ulcers, which are faid 
to abound with laudable pus. 
4. When chyle is obferved in flools, or among the materials 
ejected by vomit, we may be confident it muft have been 
brought thither by the retrograde motions of the ladeals ; for 
chyle does not previoufly exift amid the contents of the intef- 
tines, but is made in the very mouths of the ladeals, as was be- 
fore explained. 
5. When chyle, milk, or other extraneous fluids are found in 
the urinary bladder, or in any other excretory receptacle of a 
gland ; no one can for a moment believe, that thefe have been 
colleded from the mafs of blood by a morbid fecretion, as it con- 
tradids all analogy. 
Aurea duraa 
Mala ferant quercus ? Narcifco floreat alnus? 
Piuguia corticibus fudent eledtra myricae ? 
Virgil. 
IX. Retrograde Motions oj Vegetable Juices. 
There are befldes feme motions of the fap of vegetables, 
which bear analogy to our prefent fubjed ; and as the vegeta- 
ble tribes are by many philofophtrs held to be inferior animals, 
it Sect. XXIX. io. i. 
ABSORBENTS. 
267 
it may be a matter of curiofity at leaft to obferve, that their ab- 
forbent veflels feem evidently, at times, to be capable of a retro- 
grade motion. Mr. Perault cut off a forked branch of a tree., 
with the leaves on ; and inverting one of the forks into a vefl'el 
of water, observed, that the leaves on the other branch continu- 
ed green much longer than thofe of a fimilar branch, cut of7 
from the fame tree ; which Ihews, that the water from the vef- 
fel was carried up one part of the forked branch, by the retro- 
grade motion of its veflels, and fupplied nutriment fome time to 
the other part of the branch, which was out of the water. And 
the celebrated Dr. Hales found, by numerous very accurate ex- 
periments, that the fap of trees rofe upwards during the warmer 
hours of the day, and in part defeended again during the cooler 
ones. Vegetable Statics. 
It is well known that the branches of willows, and of many 
other trees, will either take root in the earth or ingraft on other 
trees, fo as to have their naturaljdiredfion inverted, and yet flour- 
ilh with vigour. 
Dr. Hope has alfo made this pleafing experiment, after the 
manner of Hales-he has placed a forked branch, cut from one 
tree, erect between two others ; then cutting off a part of the 
bark from one fork applied it to a fimilar branch of one of the 
trees in its vicinity ; and the fame of the other fork ; fo that a 
tree is feen to grow fufpended in the air, between two other 
trees ; which fupply their folter friend with due nouriOmaent. 
Miranturque novas frondet, et non fua poma. 
All thefe experiments clearly evince, that the juices of vege- 
tables can occafionally pafs either upwards or downwards in 
their abforbent fyftem of veflels. 
X. Objections an/wered. 
The following experiment, at firft view, would feem to in- 
validate this opinion of the retrograde motions of the lymphatic 
veflels, in fome difeafes. 
About a gallon of milk having been given to a hungry fwine,he 
was fuffered to live about an hour, and was then killed by a ftroke 
or two on his head with an axe.-On opening his belly the lac- 
teals were well feen filled with chyle ; on irritating many of 
the branches of them with a knife, they did not appear to emp- 
ty themfclves haftily ; but they did however carry forwards 
their contents in a little time. 
I then palled a ligature round fevcral branches of lafieals, 
and irritated them much with a knife beneath the ligature, but 
could 268 
RETROGRADE 
Sect. XXIX. 11. i. 
could not make them regurgitate their contained fluid into the 
bowels. 
I am not indeed certain, that the nerve was not at the fame 
time included in the ligature, and thus the lymphatic rendered 
unirritable or lifelefs ; but this however is certain, that it is not 
any quantity of any ftimulus, which induces the veifels of animal 
bodies to revert their motions ; but a certain quantity of a cer- 
tain ftimulus. as appears from wounds in the ftomach, which do 
not produce vomiting ; and wounds of the inteftjnes, which do 
not produce the cholera morbus. 
At Nottingham, a few years ago, two fhoemakers quarrelled, 
and one of them with a knife, which they ufe in their occupation, 
llabbed his companion about the region of the ftomach. On 
opening the abdomen of the wounded man after his death the 
food and medicines he had taken were in part found in the cav- 
ity of the belly, on the outfide of the bowels ; and there was a 
wound about half an inch long at the bottom of the ftomach ; 
which I fuppofe was diftended with liquor and food at the time 
of the accident ; and thence was more liable to be injured at its 
bottom : but during the whole time he lived, which was about 
ten days, he had no efforts to vomit, nor ever even complained of 
being tick at the ftomach ! Other cafes fimilar to this are men- 
tioned in the philofcphical tranfadlions. 
Thus, if you vellicate the throat with a feather, naufea is pro- 
duced ; if you wound it with a penknife, pain is induced, but 
not ficknefs. So if the foies of the feet of children or their arm- 
pits are tickled, convulfive laughter is excited, which ceafes the 
moment the hand is applied, fo as to rub them more forcibly. 
The experiment therefore above related upon the ladteals of 
a dead pig, which were included in a ftrict ligature, proves 
nothing ; as it is not the quantity, but the kind of ftimulus, 
which excites the lymphatic veifels into retrograde motion. 
XI. The Caufes which induce the Ret regrade Motions of Animal Vef 
fels ; and the Medicines by which the Natural Motions are refiored. 
i. Such is the conftrudlion of animal bodies, that all their 
parts, which are fubje&ed to lefs ftimuli than nature defigned, 
perform their functions with lefs accuracy : thus, when too wa- 
tery or too acefcent food is taken into the ftonrach, indigeftion, 
and flatulency, and heartburn fucceed. 
2. Another law of irritation, connate with our ekiftcnce, is, 
that all thofe parts of the body, which have previoufly been ex- 
pofed to too great a quantity of fuch ftimuli, as ftrongly affect' 
them, become for fome time afterwards difebedient to the nat- 
ural pH CT. XXIX. II. 3. 
ABSORBENTS. 
269 
ural quantity of their adapted ftimuli.-Thus the eye is inca-r 
pab.'e of feeing objects in an obfeure room, though the iris is 
quite dilated, after having been expoled to the meridian fun. 
3. There is a third law of irritation, that all the parts of our 
bodies, which have been lately fubjected to lefs Rimulus, than 
they have been accuftomcd to, when they are expoled to their 
dual quantity of ftimulus, are excited into more energetic mo- 
tions : .thus when we come from adufky cavern into the glare of 
daylight, cur eyes are dazzled ; and after emerging from the cold 
bath, rhe fkin becomes warm and red. 
4. There is a fourth law of irritation, that all the parts of our 
bodies, which are fubjefted to ftill ftronger ftimuli for a length 
of time, become torpid, and refufe to obey even thefe ftronger 
ftimuli ; and thence do their offices very imperfectly.-Thus, if 
any one locks earneftly for fome minutes on an area, an inch di- 
ameter, of red fiik, placed on a fheet of white paper, the image 
of the filk will gradually become pale, and at length totally vanifh. 
5. Nor is it the nerves of fenfe alone, as the optic and audi- 
tory nerves, that thus become torpid, when the ftimulus is with- 
drawn or their irritability decrcafed ; but the motive mufcles, 
when they are deprived of their natural ftimuli, or of their irri- 
tability, become torpid and paralytic ; as is feen in the tremulous 
hand of the drunkard in a morning ; and in the awkward ftep 
of age. 
The hollow mufcles alfo, of which the various veflels of the 
body arc conftrudied, when they are deprived of their natural 
ftimuli, or of their due degree of irritability, not only become 
tremulous, as the arterial pulfations of dying people ; but alfo 
frequently invert their motions, as in vomiting, in hyfteric fufro- 
cations, and diabetes above defcribed. 
I muft beg your patient attention, for a few moments, whilfi: 
I endeavour to explain, how the retrograde actions of our hol- 
low mufcles are the confequence of their debility; as the tremu- 
lous actions of the folid mufcles are the confequence of their de- 
bility. When, through fatigue, a mufcle can a£l no longer ; the 
antagonift mufcles, cither by their inanimate clafticiry, or by 
their animal action, draw the limb into a contrary direction : in 
the folid mufeies, as thofe of locomotion, their actions are aflb- 
ciated in tribes, which have been accuftomed to fynchronous ac- 
tion only ; hence when they are fatigued, only a fmgle contrary 
effort takes place ; which is either tremulous, when the fatigued 
mufcles are again immediately brought into aCtion ; or it is a 
pandiculation, or ftretching, where they are not immediately 
again brought into action. 
Now the motions of the hollow mufcles, as they in general 
propel 270 
RETROGRADE 
Sect. XXIX. 11. & 
propel a fluid along their cavities, are aflbciated in trains, which 
have been accuftomed to fucceffive anions : hence when one 
ring of fuch a mufcle is fatigued from its too great debility, and 
is brought into retrograde adion, the next ring from its aflbcia- 
tion falls fucceflively into retrograde adion ; and fo on through- 
out the whole canal. See Sed. XXV. 6. 
6. But as the retrograde motions of the ftomach, oefophagus, 
and fauces in vomiting are, as it were, apparent to the eye ; we 
fhall confider this operation more minutely, that the fimilar op- 
erations in the more recondite parts of our fyftem may be eafier 
under flood. 
From certain naufeous ideas of the mind, from an ungrateful 
tafte in the mouth, or from foetid fmells, vomiting is fometimes 
anftantly excited ; or even from a ftroke on the head, or from 
the vibratory motions of a flrip ; all which originate from aflbei- 
ation, or fympathy. See Sed. XX. on Vertigo. 
But when the ftomach is fubjeded to a lefs ilimulus than is 
natural, according to the firft law of irritation mentioned above, 
its motions become difturbed, as in hunger ; firft pain is produ- 
ced, then ficknefs, and at length vain efforts to vomit, as many 
authors inform us. 
But when a great quantity of wine, or of opium, is fwallow- 
ed, the retrograde motions of the ftomach do not occur till after 
feveral minutes, or even hours ; for when the power of fo ftrong 
a ftimulus ceafes, according to the fecond law of irritation, men- 
tioned above, the periftaltic motions become tremulous, and at 
length retrograde ; as is well known to the drunkard, who on 
the next morning has ficknefs and vomitings. 
When a ftill greater quantity of wine, or of opium,"br when 
naufeous vegetables, or ftrong bitters, or metallic faits, ?re taken 
into the ftomach, they quickly induce vomiting ; though all 
thefe in lefs dofes excite the ftomach into more energetic adion, 
and ftrengthen the digeftion ; as the flowers of chamomile, and 
the vitriol of zinc : for, according to the fourth law of irritation, 
the ftomach will not long be obedient to a ftimulus fo much great- 
er than is natural j but its adion becomes firft tremulous and 
then retrograde. 
7. When the motions of any veflels become retrograde, lefs heat 
of the body is produced ; for in paroxyfms of vomiting, of hyf- 
teric affedions, of diabetes, of afthma, the extremities of the 
body are cold: hence we may conclude, that thefe fyrnptoms 
arife from the debility of the parts in adion ; for an increafe of 
mufcular adion is always attended with increafe of heat. 
8. But as animal debility is owing to defed of ftimulus, or to 
defed of irritability, as fliewn above, the method of cure is eafily 
deduced ; Sect. XXIX. n. 8. 
ABSORBENTS. 
271 
deduced: when the vafcular mufcles are not excited into their 
due aft ion by the natural ftimuli, we {hould exhibit thofe med- 
icines, which poilefs a ftill greater degree of ftimulus ; amongtt 
thefe are the foetids, the volatiles, aromatics, bitters, metallic 
faits, opiates, wine, which indeed fhould be given in fmall dofes, 
and frequently repeated. To thefe {hould be added conftant, 
but moderate exercifei cheerfulnefs of mind, and change of coun- 
try to a warmer climate ; and perhaps occafionally the external 
Itimulus of blitters. 
It is alfo frequently ufeful to diminiffi the quantity of natur- 
al Itimulus for a (hort time, by which afterwards the irritability 
of the fyltem becomes increafed ; according to the third law of 
irritation above mentioned, hence the ufe of baths fomevvhat coldx 
er than animal heat, and of equitation in the open air. 
^The catalogue of difeafes owing to the retrograde motions of lymphat- 
ics is here omitted^ as it will appear in another place in this 
work. 'The following is the concltifion to this thefts of Mr. 
Charles Darwin. 
Thus have I endeavoured in a concife manner to explain the 
numerous difeafes, which deduce their origin from the inverted 
motions of the hollow mufcles of our bodies : and it is probable, 
that Saint Vitus's dance, and the ftammering of fpeech, origin- 
ate from a fimilar inverted order of the affociated motions of 
feme of the folid mufcles ; which, as it is foreign to my prefent 
purpofe, I fhall not here difeufs. 
I beg, illuttrious profeflbrs, and ingenious fellow-ttudents, that 
you will recoiled! how difficult a talk I have attempted, to evince 
the retrograde motions of the lymphatic veffels, when the vettels 
themfelves for fo many ages efcaped the eyes and glafles of phi- 
lofophers : and if you are not yet convinced of the truth of this 
theory, hold, I entreat you, your minds in fufpenfe, till Anat- 
omy draws her fword wjth happier omens, cuts afunder the knots, 
which entangle Physiology ; and, like an augur infpedting the 
immolated victim, announces to mankind the wifdom of 
heaven. 
SECT. 272 
PARALYSIS 
Sect. XXX. 1, n 
SEC T. XXX. 
PARALYSIS CF THE LIVER AND KIDNEYS. 
I. Hile-duels lefs irritable after having been [simulated much. 2- 
Jaundice from paralyfts of the bile-dudls cured by electric foocks. 
3. From bile-fones. Experiments on bile-fones. Oil vomit. 
4. Palfy of the liver, tivo cafes. $. Scirrbofty of the liver. 
6. Large livers of getfi. II. Paralyfis of the kidneys. III. 
Story of Prometheus. 
t. From the ingurgitation of fpirituous liquors into the Hom*- 
ach and duodenum, the termination of the common bile-dud in 
that bowel becomes Simulated into unnatural action, and a 
greater quantity of bile is produced from ail the fecretory vcflek 
of the liver, by the aflbciation of tHeir motions with thofe of 
their excretory duds; as has been explained in Sedion XXIV. 
and XXV. but as all parts of the body, that have been affeded 
with ftronger ftimuli for any length of time, become lefs fuf- 
ceptible of motion, from their natural weaker ftimuli, it follows, 
that the motions of the fecretory veflels, and in confequence the 
fecretion of bile, is lefs than is natural during the intervals of 
fobriety. 2. If this ingurgitation of fpirituous liquors has been 
daily continued in confiderable quantity, and is then fuddenly 
intermitted, a languor or paralyfis of the common bile-dud is 
induced ; the bile is prevented from being poured into the in- 
teltines ; and as the bilious abforbents are ilimulated into ftrong- 
er adion by its accumulation, and by the acrimony or vifeidity, 
which it acquires by delay, it is abforbed, and carried to the 
receptacle of the chyle ; or otherwife the fecretory veflels of the 
liver, by the above-mentioned ftimulus, invert their motions, and 
regurgitate their contents into the blood, as fometimes happens 
to the tears in the lacrymal fack, fee Sed. XXIV. 2. 7. and one 
kind of jaundice is brought on. 
There is reafon to believe, that the bile is moft frequently re- 
turned into the circulation by the inverted motions of thefe he- 
patic glands, for the bile does not feem liable to be abforbed by 
the lymphatics, for it foaks through the gall-duds, and is fre- 
quently found in the cellular membrane. This kind of jaundice 
is not generally attended with pain, neither at the extremity of 
the bile-dud, where it enters the duodenum, nor on the region 
of the gall-bladder. 
Mr. S. a gentleman between forty and fifty years of age, bad 
had the jaundice about fix weeks, without pain, ficknefs, or fe- 
ver ; Sect. XXX. 1. 3. 
OF THE LIVER. 
273 
ver ; and had taken emetics, cathartics, mercurials, bitters, 
chalybeates, eflential oil, and aether, without apparent advan- 
tage. On a fuppofition that the obftrufHon of the bile might 
be owing to the paralyfis, or torpid action of the common bile- 
du€l, and the Itimulants taken into the ftomach feeming to have 
no effect, 1 directed half a fcore fmart electric fhocks from a 
coated bottle, which held about a quart, to be paifed through 
the liver, and along the courfe of the common gall-duft, as near 
as could be guefled, and on that very day the (tools became yel- 
low ; he continued the elsttric (hocks a few days more, and 
his (kin gradually became clear. 
3. The bilious vomiting and purging, that affeftj fome peo- 
ple by intervals of a few weeks, is a lefs degree of this difeafe ; 
the bile-duft is lefs irritable than natural, and hence the bile 
becomes accumulated in the gall-bladder, and hepatic du£ts, 
till by its quantity, acrimony or vifcidity, a greater degree of 
irritation is produced, and it is fuddenly evacuated, or laftly 
from the abforption of the more liquid parts of the bile, the re- 
mainder becomes infpiifated, and chryftallizes into mafies too 
large to pafs, and forms another kind of jaundice, where the 
bile-du€t is not quite paralytic, or has regained its irritability. 
This difeafe is attended with much pain, which at firft is felt 
at the pit of the ftomach, exa&ly in the centre of the body, 
where the bile-dudt enters the duodenum ; afterwards, when 
the fize of the bile-ftones increafe, it is alfo felt on the right 
(ide, where the gall-bladder is fituated. The former pain at the 
pit of the ftomach recurs by intervals, as the bile-ftone is pu(h- 
ed againft the neck of the duft ; like the paroxyfms of the (tone 
in the urinary bladder, the other is a more dull and conftant pain. 
Where thefe bile-ftones are too large to pafs, and the bile- 
du<fts pofl'efs their fenfibility, this becomes a very painful and 
hopelefs difeafe. I made the following experiments with a view 
to their chemical folution. 
Some fragments of the fame bile-ftone were put into the weak 
fpirit of marine fait, which is fold in the (hops; and into folu- 
tion of mild alcali; and into a folution of cauftic alcali; and 
into oil of turpentine ; without their being diffolved. All thefe 
mixtures were after fome time put into a heat of boiling water, 
and then the oil of turpentine diffolved its fragments of bile- 
ftone, but no alteration was produced upon thofe in the other 
liquids except fome change of their colour. 
Some fragments of the fame bile-ftone were put into vitriolic 
aether, and were quickly diifolved without additional heat. 
Might not aether mixed with yolk of egg or with honey be given 
advantageoufly in bilious concretions ? 
Vol. I. Mm I 274 
PARALYSIS 
Sect. XXX. 1. 4* 
I have in two inftances feen from thirty to fifty bile-ftones 
come away by ftool, about the fize of large peas, after having 
given fix grains of calomel in the evening, and four ounces of 
oil of almonds or olives on the fucceeding morning. I have 
alfo given half a pint of good olive or almond oil as an emetic 
during the painful fit, and repeated it in half an hour, if the 
firft did not operate, with frequent good effect. 
4. Another difeafe of the liver, which I have feveral times ob- 
ferved, confifts in the inability or paralyfis of the fecretory vef- 
fels. This difeafe has generally the fame caufe as the preceding 
one, the too frequent potation of fpirituous liquors, or the too 
fudden omiffion of them, after the habit is confined ; and is 
greater or lefs in proportion, as the whole or a part of the liver 
is affected, and as the inability or paralyfis is more or lefs com- 
plete. 
This paTfy of the liver is known from thefe fymptoms, the pa- 
tients have generally palled the meridian of life, have drunk 
fermented liquors daily, but perhaps not been opprobrious 
drunkards; they lofe their appetite, then their flelh and ftrength 
diminilh in confequence, there appears no bile in their (tools, 
nor in their urine, nor is any hardnefs or fwelling perceptible 
in the region of the liver. But what is peculiar to this difeafe, 
and diftinguifhes it from all others at the firft glance of the eye, 
is the bombycinous colour of the Ikin, which, like that of full- 
grown filk worms, has a degree of tranfparency with a yellow 
tint not greater than is natural to the fcrum of the blood. 
Mr. C. and Mr. B. both very ftrong men, between fifty and 
fixty years of age, who had drunk ale at their meals inftead of 
fmall beer, but were not reputed hard-drinkers, fuddenly became 
weak, loft their appetite, flelh and ftrength, with all the fymp- 
toms above enumerated, and died in about two months from the 
beginning of their malady. Mr. C. became anafarcous a few 
days before his death, and Mr. B. had frequent and great hem- 
orrhages from an ilfue, and fome parts of his mouth, a few 
days before his death. In both thefe cafes calomel, bitters, and 
chalybeates were repeatedly ufed without effect. 
One of the patients defcribed above, Mr. C. was by trade a 
plumber ; both of them could digeft no food, and died apparent- 
ly for want of blood. Might not the transfufion of blood be 
ufed in thefe cafes with advantage ? 
5. When the paralyfis of the hepatic glands is lefs complete, 
or lefs univerfal, a feirrhofity of fome part of the liver is indu- 
ced ; for the fecretory veifels retaining fome of their living pow- 
er take up a fluid from the circulation, without being fufficient- 
ly irritable to carry it forwards to their excretory dufts; hence 
the Sect. XXX. 1.6. 
OF THE LIVER. 
275 
the body, or receptacle of each gland, becomes inflated, and this 
diftention increafes, till by its very great Itimulus inflammation is 
produced, or till thofe parts of the vifcus become totally paralyt- 
ic. This difeafe is diftinguilhable from the foregoing by the 
palpable hardnefs or largenefs of the liver ; and as the hepatic 
glands are not totally paralytic, or the whole liver not affedled, 
fome bile continues to be made. The inflammations of this 
vifcus, confequent to the fcirrhofity of it, belong to the difeafes 
of the fenfitive motions, and will be treated of hereafter. 
6. The ancients are faid to have poffefled an art of increafing 
the livers of geefe to a fize greater than the remainder of the 
goofe. Martial. 1. 13. epig. 58.-This is faid to have been done 
by fat and figs. Horace. 1. 2. fat. 8.-Juvenal fets thefe large 
livers before an epicure as a great rarity. Sat. 5. 1. 114; and 
Perfius, fat. 6.1. 71. Pliny fays thefe large goofe-livers were 
foaked in mulled milk, that is, I fuppofc, milk mixed with honey 
and wine; and adds, " that it is uncertain whether Scipio 
Metellus, of confular dignity, or M. Seftius, a Roman knight, 
was the great difcoverer of this excellent dilh." A modern 
traveller, I believe Mr. Brydone, aflerts that the art of enlarging 
the livers of geefe ftill exifts in Sicily ; and it is to be lamented 
that he did not import it into his native country, as fome meth- 
od of affecting the human liver might perhaps have been col- 
lefted from it; befides the honor he might have acquired in 
improving our giblet pies. 
Our wifer caupones, I am told, know how to fatten their 
fowls, as well as their geefe', for the London markets, by mix- 
ing gin inftead of figs and fat with their food ; by which they 
are faid to become fleepy, and to fatten apace, and probably ac- 
quire enlarged livers; as the fwine are aflerted to do, which are 
fed on the fediments of barrels in the diltilleries ; and which fo 
frequently obtains in thofe, who ingurgitate much ale, or wine, 
or drams. 
II. The irritative difeafes of the kidneys, pancreas, fpleen, 
and other glands, are analogous to thofe of the liver above dc- 
fcribed, differing only in the confequences attending their ina- 
bility to action. For inftance, when the fecretory veflels of the 
kidneys become difobedient to the ftimulus of the palling cur- 
rent of blood, no urine is feparated or produced by them ; their 
excretory mouths become filled with concreted mucus, or cal- 
culous matter, and in eight or ten days ftupor and death fuper- 
vene in confequence of the retention of the feculent part of the 
blood. 
This difeafe in a flighter degree, or when only a part of the 
■kidney is affedted, is fucceeded by partial inflammation of the 
kidney 276 
PARALYSIS, &c. 
Sect. XXX. 3. 
kidney in confequence of previous torpor. In that cafe greater 
actions of the fecretory veflels occur, and the nucleus of gravel 
is formed by the inflamed mucous membranes of the tubuli 
uriniferi, as farther explained in its place. 
This torpor, or paralyfis of the fecretory veflels of the kid- 
neys, like that of the liver, owes its origin to their being previ- 
oufly habituated to too great ftimulus; which in this country 
is generally owing to the alcohol contained in ale or wine ; and 
hence muft be regiftered amongft the difeafes owing to inebrie- 
ty ; though it may be caufed by whatever occafionally inflames 
the kidney; as too violent riding on horfeback, or the cold from 
a damp bed, or by fleeping on the cold ground ; or perhaps by 
drinking in general too little aqueous fluids. 
III. I fhall conclude this feftion on the difeafes of the liver 
induced by fpirituous liquors, with the well known (lory of 
Prometheus, which feems indeed to have been invented by phy. 
ficians in thofe ancient times, when all things were clothed in 
hieroglyphic, or in fable. Prometheus was painted as llealing 
fire from heaven, which might well reprefent the inflammable 
fpirit produced by fermentation ; which may be faid to animate 
or enliven the man of clay : whence the conquefts of Bacchus, 
as well as the temporary mirth and noife of his devotees. But 
the after punishment of thofe, who ileal this accurfed fire, is a 
vulture gnawing the liver; and well allegorifes the poor inebri- 
ate lingering for years under painful hepatic difeafes. When 
the expediency of laying a further tax on the diflillation of fpir- 
ituous liquors from grain was canvafled before the Houfe of 
Commons fome years ago, it was faid of the di (tillers, with great 
truth, <( They take the bread from the people, and convert it into 
poifon!" Yet is this manufactory of difeafe permitted to con- 
tinue, as appears by its paying into the treafury above 900,000/. 
near a million of money annually. And thus, under the names 
of rum, brandy, gin, whilky, ufquebaugh, wine, cyder, beer, and 
porter, alcohol is become the banc of the Chriftian world, as 
opium of the Mahometan. 
Evoe ! parce, Liber, 
Farce, gravi metuende thyrfo ! 
Hor. 
SECT. Sect. XXXI. 1. 
OF TEMPERAMENTS. 
277 
SECT. XXXI. 
OF TEMPERAMENTS. 
1. The temperament of decreafed irritability known by weak pulfe, 
large pupils of the eyes, cold extremities. Are generally fuppofed 
to be too irritable. Bear pain better than labour. Natives of 
Nor th-America contrafed with thofe upon the coaf of Africa. 
Narrow and broad fjoulderedpeople. Irritable confitutions bear 
labour better than pain. . II. Temperament oj increafedfenfbility. 
Liable to intoxication, to infammation, hamoptoe, gutta ferena, en- 
thtfiafm, delirium, reverie. Thefe conf itutions are indolent to 
voluntary exertions, and dull to irritations. The natives of South- 
America, and brute animals of this temperament. 111. Of in- 
creafed voluntarity ; thefe are fubjelt to locked jaw, convuifohs, 
epilepfy, mania. Are very active, bear cold, hunger, fatigue. 
Are fuited to great exertions. This temperament difinguifaet 
mankind from other animals. IV. Of increafed afociation. 
Thefe have great memories, are liable to quartan agues, and 
fronger fympathies of parts with each other. V. Change of 
temperaments into one another. 
Ancient writers have fpoken much of temperaments, but 
without fufficient precifion. By temperament of the fyftem 
fhould be meant a permanent predifpofition to certain claifes cf 
difeafes: without this definition a temporary predifpofition to 
every diftinct malady might be termed a temperament. There 
are four kinds of conftitution, which permanently deviate from 
good health, and are perhaps fufficiently marked to be diltin- 
guiihed from each other, and confiitute the temperaments or 
predifpofitions to the irritative, fenfitive, voluntary, and alfoci- 
ate claifes of difeafes. 
I. The Temperament of decreefed Irritability. 
The difeafes, which are caufed by irritation, moft frequently 
originate from the defeat of it; for thofe, which are immedi- 
ately owing to the excefs of it, as the hot fits of fever, are gener- 
ally occafioned by an accumulation of fenforial power in confe- 
quence of a previous defeat of irritation, as in the preceding 
cold fits of fever. Whereas the difeafes, which are caufed by 
fenfation and volition, molt frequently originate from the excefs 
of thofe fenforial powers, as will be explained below. 
The temperament of decreafcd irritability appears from the 
following 278 
OF TEMPERAMENTS. 
Sect. XXXI. 1. 
following circumstances, which (hew that the mufcular fibres 
or organs of fenfe are liable to become torpid or quiefcent from 
lefs defeat of Stimulation than is productive of torpor or quief- 
cence in other constitutions. 
i. The firft is the weak pulfe, which in fome constitutions 
is at the fame time quick. 2. The next molt marked criterion 
of this temperament is the largenefs of the aperture of the iris, 
or pupil of the eye, which has been reckoned by fome a beauti- 
ful feature in the female countenance, as an indication of deli- 
cacy, but to an experienced obferver it is an indication of de- 
bility, and is therefore a defeft, not an excellence. The third 
moft marked circumstance in this constitution is, that the ex- 
tremities, as the hands and feet, or nofe and ears, are liable to 
become cold and pale in fituations in refpeCt to warmth, where 
thofe of greater Strength are not affefted. Thofe of this tem- 
perament are fubject to hyfteric affeCtions, nervous fevers, hy- 
drocephalus, fcrofula, and confumption, and to all other difeafes 
of debility. 
Thofe, who poflefs this kind of constitution, are popularly 
fuppofed to be more irritable than is natural, but are in reality 
lets fo. This miftake has arifen from their generally having a 
greater quicknefs of pulfe, as explained in Sect. XII. 1. 4. XII. 
3. 3 ; but this frequency of pulfe is not neceflary to the temper- 
ament, like the debility of it. 
Perfons of this temperament are frequently found amongSt 
the fofter fex, and amongSt narrow Shouldered men ; who are 
faid to bear labour worfe, and pain better than others. This 
laft circumftance is fuppofed to have prevented the natives of 
North America from having been made Slaves by the Europeans. 
They are a narrow-Shouldered race of people, and will rather 
expire under the laih, than be made to labour. Some nations 
of Afia have fmall hands, as may be feen by the handles of their 
feymetars; which with their narrow Shoulders Shew, that they 
have not been accultomed to fo great labour with their hands 
and arms, as the European nations in agriculture, and thofe on 
the coalls of Africa in fwimming and rowing. Dr. Manning- 
ham, a popular accoucheur in the beginning of this century, 
obferves in his aphorifms, that broad-Shouldered men procreate 
broad-Shouldered children. Now as labour Strengthens the 
mufcles employed, and increafes their bulk, it would feem that 
a few generations of labour or of indolence may in this refpeft 
change the form and temperament of the body. 
On the contrary, thofe who are happily pofTcfled of a great de- 
gree of irritability, bear labour better than pain ; and arc Strong, 
active, and ingenious. But there is not properly a temperament 
of Sect. XXXI. 1. 
OF TEMPERAMENTS. 
279 
of increafed irritability tending to difeafe, becaufe an increafed 
quantity of irritative motions generally induces an increafe of 
pleafure or pain, as in intoxication, or inflammation 5 and then 
the new motions are the immediate confequences of increafed 
fenfation, not of increafed irritation ; which have heijce been fo 
perpetually confounded with each other. 
II. Temperament of Senftbility. 
There is not properly a temperament, or a predifpofition to 
difeafe, from decreafed fenfibility, fince irritability and not fenfi- 
bility is immediately neceflary to bodily health. Hence it is the 
excefs of fenfation alone, as it is the defetfl of irritation, that molt 
frequently produces difeafe. This temperament of increafed fen- 
fibility is known from the increafed activity of all thofe motions 
of the organs of fenfe and mufcles, which are exerted in confe- 
quence of pleafure or pain, as in the beginning of drunkennefs, 
and in inflammatory fever. Hence thofe of this conftitution 
are liable to inflammatory difeafes, as hepatitis ; and to that 
kind of confumption which is hereditary, and commences with 
flight repeated htemoptoe. They have high-coloured lips, fre- 
quently dark hair and dark eyes with large pupils, and are in 
that cafe fubject to gutta ferena. They are liable to enthufiafm, 
delirium, and reverie. In this laft circumflance they are liable 
to flart at the clapping of a door ; becaufe the more intent any 
one is on the palling current of his ideas, the greater furprife he 
experiences on their being difl'evered by fome external violence, 
as explained in Sedt. XIX. on reverie. 
As in thefe conftitutions more than the natural quantities of 
fenfitive motions are produced by the increafed quantity of fen- 
fation exifting in the habit, it follows, that the irritative motions 
will be performed in fome degree with lefs energy, owing to the 
great expenditure of fenforial power on the fenfitive ones. 
Hence thofe of this temperament do not attend to flight ftimu- 
lations, aS explained in Seift. XIX. But when a ftimulus is fo 
great as to excite fenfation, it produces greater fenfitive actions 
of the fyftem than in others ; fuch as delirium or inflammation. 
Hence they are liable to be abfent in company ; fit or lie long 
in one pofture ; and in winter have the fkin of their legs burnt 
into various colours by the fire. Hence alfo they are fearful of 
pain ; covet mufic and fleep 5 and delight in poetry and romance. 
As the motions in confequence of fenfation are more than nat- 
ural, it alfo happens from the greater expenditure of fenforial 
power on them, that the voluntary motions are lefs eafily exerted. 
Hence 280 
OF TEMPERAMENTS. 
Sect. XXXI. > 
Hence the fubjebts of this temperament are indolent in refpebt 
to all voluntary exertions, whether of mind or body. 
A race of people of this defcription feems to have been found 
by the Spaniards in the iflands of America, where they firft 
landed, ten of whom are faid not to have confumed more food 
than one Spaniard, nor to have been capable of more than one 
tenth of the exertion of a Spaniard. Robertfon's Hiftory.-In 
a Rate fimilar to this the greateft part of the animal world pafs 
their lives, between fleep and inactive reverie, except when they 
are excited by the call of hunger. 
III. The Temperament of increafed Voluntarily. 
Those of this conftitution differ from both the laft mentioned 
in this, that the pain, which gradually fubfides in the firlt, and 
is productive of inflammation or delirium in the fecond, is in 
this fucceeded by the exertion of the mufcles or ideas, which 
are moll frequently connected with volition; and they arc 
thence fubjedt to locked jaw, convulfions, epilepfy, and mania, 
as explained in Se€t. XXXIV. Thofe of this temperament at- 
te/id to the flighted: irritations or fenfations, and immediately ex- 
ert themfelves to obtain or avoid the objects of them ; they can 
at the fame time bear cold and hunger better than others, of 
W'hich Charles the Twelfth of Sweden was an inftance. They 
are fuited and generally prompted to all great exertions of genius 
or labour, as their defires are more extenfive and more vehe- 
ment, and their powers of attention and of labour greater. It is 
this facility of voluntary exertion, which dilhnguiflies men from 
brutes, and w'hich has made them lords of the creation. 
IV. The Temperament of increafed Affociation. 
This cohftitution confifts in the too great facility, with which 
the fibrous motions acquire habits of afl'ociation, and by which 
thefe affociations become proportionably itronger than in thofe 
of the other temperaments. Thofe of this temperament are flow 
in voluntary exertions, or in thofe dependent on fenfation, 
or on irritation. Hence great memories have been faid to be 
attended with lefs fenfe and lefs imagination from Ariibatle 
down to the prefent time ; for by the word memory thefe writers 
only underftood the unmeaning repetition of words or numbers 
in the order they were received, without any voluntary efforts 
of the mind. 
In this temperament thofe affociations of motions, which are 
commonly termed fympathies, act with greater certainty and 
energy. Sect. XXXI. 5. 
OF TEMPERAMENTS. 
281 
energy, as thofe between difturbed vifion and the inverfion of 
the motion of the ftomach, as in fea ficknefs ; and the pains in 
the fhoulder from hepatic inflammation. Add to this, that the 
catenated circles of actions are of greater extent than in the other 
conftitutions. Thus if a«ftrong vomit or cathartic be exhibited 
in this temperament, a fmaller quantity will produce as great 
an effect, if it be given tome weeks afterwards; whereas in other 
temperaments this is only to be expected, if it be exhibited in a 
few days after the firft dofe. Hence quartan agues are formed 
in thofe of this temperament, as explained in Seilion XXXII. 
on difeafes from irritation, and other intermittents are liable to 
recur from flight caufes many weeks after they have been cured 
by the bark. 
V. The firft of thefe temperaments differs from the ftandard 
of health from defeat, and the others from excefs of fenforial 
power ; but it fometimes happens that the fame individual, from 
the changes introduced into his habit by the different feafons of 
the year, modes or periods of life, or by accidental difeafes, 
paffes from one of thefe temperaments to another. Thus a long 
ufe of too much fermented liquor produces the temperament of 
increafed fenfibility; great indolence and folitude that of de- 
creafed irritability ; and want of the neceffaries of life that of 
increafed voluntarity. 
Vol., I. 
N k 
SECT. 282 
DISEASES 
Sect. XXXII. i. 
SECT. XXXII. 
DISEASES OF IRRITATION. 
I. Irritative fevers with firong pulfe. With weak pulfe. Symp- 
toms of fever. Their fource. IL I. ^uick pulfe is owing to 
decreafed irritability. 2. Not in feep or in apoplexy. 3. From 
inanition. Owing to deficiency of fenforial power. III. 1. Cattfes 
of fever. From defect of heat. Heat from fecretions. Pain of 
cold in the loins and forehead. 2. Great expenfe offenforial power 
in the vital motions. Immerfton in cold water. Succeeding glow 
of heat. Difficult refpiration in cold bathing explained. Why 
the cold bath invigorates. Bracing and relaxation are mechanical 
terms. 3. Ufes of cold bathing. Ufes of cold air in fevers. 4. 
Ague fits from cold air. Whence their periodical returns. IV. 
Def eEi of difiention a caufe offever. Deficiency of blood. Trans- 
fufion of blood. V. 1. Defect of momentum of the blood from me- 
chanic ftimuli. 2. Air injeEled into the blood-veffels. 3. Exer- 
cife increafes the momentum of the blood. 4. Sometimes bleeding 
increafes the momentum of it. VI. Influence of the fun and moon 
on difeafes. The chemical ftimulus of the blood. Menfiruation 
obeys the lunations, ^tieries. VII. ^uiefcence of large glands 
a caufe offever. Swelling of the pracordia. VIII. Other caufes 
of quiefcence, as hunger, bad air, fear, anxiety. IX. I. Symp- 
toms of the cold fit. 2. Of the hot fit. 3. Second cold fit why. 
4. Inflammation introduced, or delirium, or fiupor. X. Recap- 
itulation. Fever not an effort of nature to relieve herfelf. Doc- 
trine of fpafm. 
I. When the contractile fides of the heart and arteries per- 
form a greater number of pulfations in a given time, and move 
through a greater area at each pulfation, whether thefe motions 
are occafioned by the ftimulus of the acrimony or quantity of the 
blood, or by their aflbciation with other irritative motions, or by 
the increafed irritability of the arterial fyftem, that is, by an in- 
creafed quantity of fenforial power, one kind of fever is produ- 
ced ; which may be called Synocha irritativa, or Febris irritativa 
pulfu forti, or irritative fever with ftrong pulfe. 
When the contractile fides of the heart and arteries perform 
a greater number of pulfations in a given time, but move through 
a much lefs area at each pulfation, whether thefe motions are 
occafioned by defect of their natural ftimuli, or by the defect of 
other irritative motions with which they are aflbciated, or from 
the inirritability of the arterial fyftem, that is, from a decreafed 
quantity XXXII. 2. I. 
OF IRRITATION. 
283 
quantity of fenforial power, another kind of fever arifes; which 
may be termed, Typhus irritativus, or Febris irritativa pulfu de- 
bili, or irritative fever with weak pulfe. The former of thefe 
fevers is the fynocha of nofologifts, and the latter the typhus mi- 
tior, or nervous fever. In the former there appears to be an 
increafe of fenforial power, in the latter a deficiency of it ; 
which is (hewn to be the immediate caufe of ftrength and weak- 
nefs, as defined in Se€t. XII. 1.3. 
It fhould be added, that a temporary quantity of ftrength or 
debility may be induced by the defect or excefs of ftimutus above 
what is natural; and that in the fame fever debility always exifs 
during the cold fit, though jlrength does not always exif during the 
hot fit. 
Thefe fevers are always connected with, and generally indu- 
ced by, the difordered irritative motions of the organs of fenfe, 
or of the inteftinal canal, or of the glandular fyftem, or of the 
abforbent fyftem ; and hence are always complicated with fome 
or many of thefe difordered motions, which are termed the fymp- 
toms of the fever, and which compofe the great variety in thefe 
difeafes. 
The irritative fevers both with ftrong and with weak pulfe, 
as well as the fenfitive fevers with ftrong and with weak pulfe, 
which are to be defcribed in the next feftion, are liable to peri- 
odical remiflions, and then they take the name of intermittent 
fevers, and are diftinguiftied by the periodical times of their 
accefs. 
II. For the better illuftration of the phenomena of irritative 
fevers we muft refer the reader to the circumftances of irritation 
explained in Setft. XII. and (hall commence this intricate fubject 
by fpeaking of the quick pulfe, and proceed by confidering many 
of the caufes, which either feparately or in combination moft 
frequently produce the cold fits of fevers. 
1. If the arteries are dilated but to half their ufual diameters, 
though they contract twice as frequently in a given time, they 
will circulate only half their ufual quantity of blood : for as 
they are cylinders, the blood which they contain muft be as the 
fquares of their diameters. Hence when the pulfe becomes 
quicker and fmaller in the fame proportion, the heart and arte- 
ries ad! with lefs energy than in their natural ftate. See Setft. 
XII. 1. 4. 
That this quick fmall pulfe is owing to want of irritability, 
appears, firft, becaufe it attends other fymptoms of want of ir- 
ritability ; and, fecondly, becaufe on the application of a ftimu- 
lus greater than ufual, it becomes flower and larger. Thus in 
fold fits of agues, in hyfteric palpitations of the heart, and when 
the 284 
DISEASES 
Sect. XXXII. 2. a. 
the body is much exhausted by haemorrhages, or by fatigue, as 
well as in nervous fevers, the pulfe becomes quick and fmall; 
and fccondly, in all thofe cafes if an increafe of ftimulus be ad- 
ded, by giving a little wine or opium ; the quick fmall pulfe be- 
comes flower and larger, as any one may eafdy experience on 
himfelf, by counting his pulfe after drinkitjg one or two glafles 
of wine, when he is faint from hunger or fatigue. 
Now nothing can fo ftrongty evince that this quick fmall 
pulfe is owing to defeat of irritability, as that an additional 
ftimulus, above what is natural, makes it become flower and 
larger immediately : for what is meant by a defeft of irritabili- 
ty, but that the arteries and heart are not excited into their ufual 
exertions by their ufual quantity of ftimulus ? but if you increafe 
the quantity of ftimulus, and they immediately aft with their 
ufual energy, this proves their previous want of their natural de- 
gree of irritability. Thus the trembling hands of drunkards in 
a morning become fteady, and acquire ftrength to perform their 
ufual offices, by the accuftomed ftimulus of a glafs or twp of 
brandy. 
2. In fleep and in apoplexy the pulfe becomes flower, which 
is not owing to defect of irritability, for it is at the fame time 
larger ; and thence the quantity of the circulation is rather in- 
creafed than diminiflied. In thefe cafes the organs of fenfe are 
clofed, and the voluntary power is fufpended, while the motions 
dependent on internal irritations, as thofe of digeftion and fccre- 
tion, are carried on with more than their ufual vigour ; which 
has led fuperficial dbfervers to confound thefe cafes with thofe 
arifing from want of irritability. Thus if you lift up the eyelid 
of an apopleftic patient, who is not aftually dying, the iris 
will, as ufual, contraft itfelf, as this motion is aflbeiated with 
the ftimulus of light; but it is not fo in the laft ftages of ner- 
vous fevers, where the pupil of the eye continues expanded in 
the broad day-light: in the former cafe there is a want of volun- 
tary power, in the latter a want of irritability. 
Hence alfo thofe conftitutions which are deficient in quantity 
of irritability, and which poflefs too great fenfibility, as during 
the pain of hunger, 01 hyfteric fpafms, or nervous headachs, are 
generally fuppofed to have too much irritability; and opium, 
which in its due dofe is a moft powerful ftimulant, is erronq.- 
oufly called a fedative; becaufe by increafing the irritative mo- 
tions it decreafes the pains arifing from defeft of them. 
Why the pulfe ftiould become quicker both from an increafe 
of irritation, as in the fynocha irritativa, or irritative fever with 
ftrong pulfe ; and from the decreafe of it, as in the typhus irrita- 
tivus, or irritative fever with weak pulfe ; feems paradoxical. 
The Sect. XXXII. 2. 3. 
OF IRRITATION. 
285 
The former circumftance needs no illuftration; fince if the ftimu- 
lus of the blood, or the irritability of the fanguiferous fyftem be 
increafed, and the ftrength of the patient not diminfhed, it is 
plain that the motions mull be performed quicker and ftronger. 
In the latter circumllance the weaknefs of the mufcular pow- 
er of the heart is foon over-balanced by the elafticity of the 
coats of the arteries, which they poflefs befides a mufcular power 
of contraction ; and hence the arteries are diftended to lefs than 
their ufual diameters. The heart being thus flopped, when it 
is but half emptied, begins fooner to dilate again; and the ar- 
teries being dilated to lefs than their ufual diameters, begin fo 
much fooner to contract themfelves; infomuch, that in the laft 
ftages of fevers with weaknefs the frequency of pulfation of the 
heart and arteries become doubled ; which, however, is never 
the cafe in fevers with ftrength, in which they feldom exceed 
118 or 120 pulfations in a minute. It muft be added, that in 
thefe cafes, w'hile the pulfe is very fmall and very quick, the 
heart often feels large, and labouring to one's hand ; which co- 
incides with the above explanation, fhewing that it does not 
completely empty itfelf. 
3. In cafes however of debility from paucity of blood, as in 
animals which are bleeding to death in the flaughter-houfe, the 
quick pulfations of the heart and arteries may be owing to their 
not being diftended to more than half their ufual diaftole •, and 
in confequence they muft contraCt fooner, or more frequently, 
in a given time. As weak people are liable to a deficient quan- 
tity of blood, this caufe may occafionally contribute to quicken 
the pulfe in fevers with debility, which may be known by ap- 
plying one's hand upon the heart as above ; but the principal 
caufe I fuppofe to confift in the diminution of fenforial power. 
When a mufcle contains, or is fupplied with but little fenforial 
power, its contraCiion foon ceafes, and in conefquence may foon 
recur, as is feen in the trembling hands of people weakened by 
age or by drunkennefs. See SeCt. XII. 1. 4. XII. 3. 4. 
It may neverthclefs frequently happen, that both the deficiency 
of ftimulus, as where the quantity of blood is leffened (as de- 
fcribed in No. 4. of this feCtion), and the deficiency of fenforial 
pow'er, as in thofe of the temperament of inirritabilty, defcribed 
in SeCt. XXXI. occur at the fame time; which will thus add 
to the quicknefs of the pulfe and to the danger of the difeafe. 
III. 1. A certain degree of heat is neceflary to mufcular mo- 
tion, and is, in confequence, efl'ential to life. This isobferved 
in thofe animals and infeCls which pafs the cold feafon in a tor- 
pid ftate, and which revive on being warmed by the fire. This 
neceflary ftimulus of heat has two fources ; one from the fluid 
atmoiphere 286 
DISEASES 
Sect. XXXII. 3. 2. 
atmofphere of heat, in which all things are immerfed, and the 
other from the internal combinations of the particles, which 
form the various fluids, which are produced in the extenfive 
fyftems of the glands. When either the external heat, which 
furrounds us, or the internal production of it, becomes leflened 
to a certain degree, the pain of cold is perceived. 
This pain of cold is experienced moft fenfibly by our teeth, 
when ice is held in the mouth ; or by our whole fyftem after 
having been previously accuftomed to much warmth. It is 
probable, that this pain does not arife from the mechanical or 
chemical effects of a deficiency of heat; but that, like the or- 
gans of fenfe by which we perceive hunger and thirft, this fenfe 
of heat fuffers pain, when the ftimulus of its objeCt is wanting 
to excite the irritative motions of the organ ; that is, when the 
fenforial power becomes too much accumulated in the quiefeent 
fibres. See Sect. XII. 5. 3. For as the periftaltic motions of 
the ftomach are leflened, when the pain of hunger is great, fo 
the action of the cutaneous capillaries are leflened during the 
pain of cold ; as appears by the palenefs of the fkin, as explain- 
ed in SeCI. XIV. 6. on the production of ideas. 
The pain in the fmall of the back and forehead in the cold 
fits of the ague, in nervous hemicrania, and in hyfteric parox- 
yims, when all the irritative motions are much impaired, feems 
to arife from this caufe ; the veflels of thefe membranes or 
mufcles become torpid by their irritative aflbeiations with other 
parts of the body, and thence produce lefs of their accuftomed 
fecretions, and in confequence lei's heat is evolved, and they 
experience the pain of cold ; which coldnefs may often be felt 
by the hand applied upon the affected part. 
2. The importance of a greater or Jefs deduction of heat 
from the fyftem will be more eafy to comprehend, if we firit 
confider the great expenfe of fenforial power ufed in carrying 
on the vital motions ; that is, which circulates, abforbs, fecretes, 
aerates, and elaborates the whole mafs of fluids with unceafing 
afliduity. The fenforial power, or fpirit of animation, ufed in 
giving perpetual and ftrong motion to the heart, which over- 
comes the elafticity and vis inertia of the whole arterial fyftem ; 
next the expenfe of fenforial power in moving with great force 
and velocity the innumerable trunks and ramifications of the 
arterial fyftem ; the expenfe of fenforial power in circulating 
the whole mafs of blood through the long and intricate intor- 
tions of the very fine veflels, which compofe the glands and 
capillaries ; then the expenfe of fenforial power in the exer- 
tions of the abforbent extremities of all the laifleals, and of all 
the lymphatics, which open their mouths on the external fur- 
face Sect. XXXII. 3. 2. 
OF IRRITATION. 
287 
face of the fkin, and on the internal furfaces of every cell or 
interftice of the body ; then the expenfe of fenforial power in 
the venous abforption, by which the blood is received from the 
capillary veflels, or glands, where the arterial power ceafes, and 
is drunk up, and returned to the heart ; next the expenfe of 
fenforial power ufed by the mufcles of refpiration in their of- 
fice of perpetually expanding the bronchia, or air-veflels, of the 
lungs ; and laftly in the unceafing periflaltic motions of the 
Itomach^md whole fyftcm of inteftines, and in all the fecre- 
tions of bile, gaftric juice, mucus, perfpirable matter, and the 
various excretions from the fyltem. If we confider the ceafe- 
lefs expenfe of fenforial power thus perpetually employed, it 
will appear to be much greater in a day than all the voluntary 
exertions of our mufcles and organs of fenfe confume in a 
week ; and all this without any fenfible fatigue ! Now, if but 
a part of thefe vital motions are impeded, or totally flopped for 
but a fhort time, we gain an idea that there mull be a great ac- 
cumulation of fenforial power ; as its production in thefe or- 
gans, which are fubjcCl to perpetual activity, is continued dur- 
ing their quiefccnce, and is in confequence accumulated. 
While, on the contrary, where thofe vital organs ad too for- 
cibly by increafe of flimulus without a proportionally-increafed 
production of fenforial power in the brain, it is evident, that a 
great deficiency of aCtion, that is torpor, muft foon follow, as 
in fevers ; whereas the locomotive mufcles, which aCt only by 
intervals, are neither liable to fo great accumulation of fenforial 
power during their times of inactivity, por to fo great an ex- 
hauftion of it during their times of aCtion. 
Thus, on going into a very cold bath, fuppofe at 33 degrees 
of heat on Fahrenheit's fcale, the aCtion of the fubcutaneous 
capillaries, or glands, and of the mouths of the cutaneous ab- 
forbents is diminifhed, or ceafes for a time. Hence lefs or no 
blood pafles thefe capillaries, and palenefs fucceeds. But foon 
after emerging from the bath, a more florid colour and a greater 
degree of heat are generated on the fkin than was poflefled be- 
fore immerfion ; for the capillary glands, after this quiefeent 
ftate, occafioned by the want of ftimulus, become more irritable 
than ufual to their natural ftimuli, owing to the accumulation of 
fenforial power, and hence a greater quantity of blood is tranf- 
mitted through them, and a greater fecretion of perfpirable 
matter; and, in confequence, a greater degree of heat fucceeds. 
During the continuance in cold water the breath is cold, and 
the aCl of refpiration quick and laborious ; which have gener- 
ally been afcribed to the obftruCtion of the circulating fluid by 
a fpafrn of the cut;- ■ nd by a consequent accumu- 
lation 288 
DISEASES 
Sect. XXXII. 3. 3. 
lation of blood in the lungs, occafioned by the preflure as well 
as by the coldnefs of the water. This is not a fatisfaftory ac- 
count of this curious phenomenon, fince at this time the 
whole circulation is lefs, as appears from the fmallnefs of the 
pulfe and coldnefs of the breath ; which fhew that lefs blood 
pafles through the lungs in a given time ; the fame laborious 
breathing immediately occurs when the palenefs of the fkin is 
produced by fear, where no external cold or preflure are applied. 
The minute veflels of the bronchia, through which the blood 
pafles from the arterial to the venal fyflem, and which corref- 
pond with the cutaneous capillaries, have frequently been ex- 
pofed to cold air, and become quiefeent along with thofe of the 
ikin ; and hence their motions are fo aflbeiated together, that 
when one is affected either with quiefcence or exertion, the 
other fympathizes with it, according to the laws of irritative 
aflbeiation. See Seel. XXVII. I. on haemorrhages. 
Befides the quiefcence of the minute veflels of the lungs, 
there are many other fyftems of veflels which become torpid 
from their irritative aflbeiations with thofe of the fkin, as the 
abforbents of the bladder and inteftines ; whence an evacuation 
of pale urine occurs, when the naked ikin is expofed only to 
the coldnefs of the atmofphere ; and fpiinkling the naked body 
with cold water is known to remove even pertinacious confti- 
pation of the bowels. From the quiefcence of fuch extenfive 
fyftems of veflels as the glands and capillaries of the ikin, and 
the minute veflels of the lungs, with their various abforbent fe- 
ries of veflels, a great accumulation of fenforial powers is occa- 
fioned ; part of which is again expended in the increafed ex- 
ertion of all thefe veflels, with an univerfal glow of heat in con- 
fequence of this exertion, and the remainder of it adds vigour 
to both the vital and voluntary exertions of the whole day. 
If the activity of the fubcutaneous veflels, and of thofe with 
which their actions are aflbeiated, was too great before cold im- 
meriion, as in the hot days of fummcr, and by that means the 
fenforial power was previoufly diminiflied, we fee the caufe 
why the cold bath gives fuch prefent ftrength ; namely, by flop- 
ping the unneceflary activity of the fubcutaneous veflels, and 
thus preventing the too great exhauftion of fenforial power ; 
which, in metaphorical language, has bden called bracing the 
fyftem : which is, however, a mechanical term, only applicable 
to drums, or mufical ftrines : as on the contrary the word re- 
taxation^ when applied to living animal bodies, can only mean 
too fmall a quantity of ftimulus, or too fmall a quantity of 
fenforial power ; as explained in Sebt. XII. i. 
3. This experiment of cold bathing prefents us with a fimple 
fever-fit ; Sect. XXXII. 3. 4. 
OF IRRITATION. 
289 
fever-fit; for the pulfe is weak, fmall, and quick during the 
cold immerfion ; and becomes ftrong, full, and quick during 
the fubfequent glow of heat ; till in a few minutes thefe fymp- 
toms fubfide, and the temporary fever ceafes. 
In thofe conftitutions where the degree of inirritability, or of 
debility, is greater than natural, the coldnefs and palenefs of 
the Ikin with the quick and weak pulfe continue a long time 
after the patient leaves the bath ; and the fubfequent heat ap- 
proaches by unequal flulhings, and he feels himfelf difordered 
for many hours. Hence the bathing in a cold fpring of water, 
where the heat is but forty eight degrees on Fahrenheit's ther- 
mometer, much difagrees with thofe of weak or inirritable hab- 
its of body ; who poflefs fo little fenforial power, that they 
cannot without injury bear to have it diminilhed even for a 
ihort time ; but who can neverthelefs bear the more temperate 
coldnefs of Buxton bath, which is about eighty degrees of heat, 
and which ftrengthens them, and makes them by habit lefs lia- 
ble to great quiefcence from fmall variations of cold ; and thence 
lefs liable to be difordered by the unavoidable accidents of life. 
Hence it appears, why people of thefe inirritable conftitutions, 
which is another expreffion for fenforial deficiency, are often 
much injured by bathing in a cold fpring of water ; and why 
they Ihould continue but a very fhort time in baths, which are 
colder than their bodies ; and fhould gradually increafe both 
the degree of the coldnefs of the water, and the time of their 
continuance in it, if they would obtain falutary effefts from cold 
immerfions. See Se&. XII. 2. 1. 
On the other hand, in all cafes where the heat of the exter- 
nal furface of the body, or of the internal furface of the lungs, 
is greater than natural, the ufe of expofure to cool air may be 
deduced. In fever-fits attended with ftrength, that is with 
great quantity of fenforial power, it removes the additional ftim- 
ulus of heat from the furfaces above mentioned, and thus pre- 
vents their excefs of ufelefs motion ; and in fever-fits attended 
with debility, that is with a deficiency of the quantity of fenfo- 
rial power, it prevents the great and dangerous wafte of fenfo- 
rial power expended in the unneceflary increafe of the actions 
of the glands and capillaries of the Ikin and lungs. 
4. In the fame manner, when any one is long expofed to 
very cold air, a quiefcence is produced of the cutaneous and 
pulmonary capillaries and abforbents, owing to the deficiency 
of their ui'ual ftimulus of heat ; and this quiefcence of fo great 
a quantity of veffels affefts, by irritative aflbeiation, the whole 
abforbent and glandular fyftem, which becomes in a greater or 
lefs degree quiefeent, and a cold fit of fever is produced. 
Vol. I. O o If 290 
DISEASES 
Sect. XXXII. 4. t. 
I£ the deficiency of the ftimulus of heat is very great, the qui- 
efcence becomes fo general as to exftinguifh life, as in thofe who 
are frozen to death. 
If the deficiency of heat be in lefs degree, but yet fo great as 
in fome meafure to diforder the fyftem, and Ihould occur the 
fucceeding day, it will induce a greater degree of quiefcence 
than before, from its acting in concurrence with the period of 
the diurnal circle of actions, explained in Sedl. XXXVI. Hence 
from a fmall beginning a greater and greater degree of quief- 
cence may be induced, till a complete fever-fit is formed ; and 
which will continue to recur at the periods by which it was 
produced. See Sect. XVII. 3.6. 
If the degree of quiefcence occafioned by defect of the ftimu- 
lus of heat be very great, it will recur a fecond time by a {light- 
er caufe, than that which firft induced it. If the caufe, which 
induces the fecond fit of quiefcence, recurs the fucceeding day, 
the quotidian fever is produced ; if not till the alternate day, the 
tertian fever ; and if not till after feventy-two hours from the 
firft fit of quiefcence, the quartan fever is formed. This laft 
kind of fever recurs lefs frequently than the other, as it is a dif- 
eafe only of thofe of the temperament of affociability, as men- 
tioned in Sect XXXI.; for in other conftitutions the capability 
of forming a habit ceafes, before the new caufe of quiefcence is 
again applied, if that does not occur fooner than in feventy-two 
hours. 
And hence thofe fevers, whofe caufe is from cold air of the 
night or morning, are more liable to obferve the folar day in 
their periods; while thofe from other caufes frequently obferve 
the lunar day in their periods, their paroxyfms returning near an- 
hour later every day, as explained in Sect. XXXVI. 
IV. Another frequent caufe of the cold fits of fever is the 
defect of the ftimulus of diftention. The whole arterial fyftem 
would appear, by the experiments of Haller, to be irritable by 
no other ftimulus, and the motions of the heart and alimentary 
canal are certainly in fome meafure dependent on the fame caufe. 
See Se<!ft. XIV. 7. Hence there can be no wonder, that the 
diminution of diftention ihould frequently induce the quief- 
cence, which conftitutes the beginning of fever-fits. 
Monfieur Lieutaud has judicioully mentioned the deficiency 
of the quantity of blood amongft the caufes of difeafes, which 
he fays is frequently evident in diflections : fevers are hence 
brought on by great haemorrhages, diarrhoeas, or other evacua- 
tions ; or from the continued ufe of diet, which contains but 
little nouriihment; or from the exhauftion occafioned by vio- 
lent fatigue, or by thofe chronic difeafes in which the d'geftion 
is Sect. XXXII. 5. 1. 
OF IRRITATION. 
291 
is much impaired ; as where the ftomach has been long affected 
with the gout or fcirrhus ; or in the paralyfis of the liver, as de. 
fcribed in Se€L XXX. Hence a paroxyfm of gout is liable to 
recur on bleeding or purging ; as the torpor of fome vifcus, 
which precedes the inflammation of the foot, is thus induced by 
the want of the ftimulus of diftention. And hence the extremi- 
ties of the body, as the nofe and fingers, are more liable to be- 
come cold, when we have long abftained from food ; and hence 
the pulfe is increafed both in ftrength and velocity above the 
natural ftandard after a full meal by the ftimulus of diftention. 
However, this ftimulus of diftention, like the ftimulus of heat 
above defcribed, though it contributes much to the due action 
not only of the heart, arteries, and alimentary canal, but feems 
neceffary to the proper fecretion of all the various glands ; yet 
perhaps it is not the foie caufe of any of thefe numerous mo- 
tions : for as the lafleals, cutaneous abforbents, and the various 
glands appear to be ftimulated into action by the peculiar pun- 
gency of the fluids they abforb, fo in the inteftinal canal the 
pungency of the digefting aliment, or the acrimony of the faeces, 
feems to contribute, as well as their bulk, to promote the perif- 
taltic motions ; and in the arterial fyftem, the momentum of the 
particles of the circulating blood, and their acrimony, ftimulate 
the arteries, as well as the diftention occafioned by it. Where 
the pulfe is fmall this defeat of diftention is prefent, and con- 
tributes much to produce the febris irritativa pulfu debili, or ir- 
ritative fever with weak pulfe, called by modern writers nervous 
fever, as a predifponent caufe. See Secft. XII. i. 4. Might 
not the transfufion of blood, fuppofe of four ounces daily from 
a ftrong man, or other healthful animal, as a fheep or an afs, be 
ufed in the early ftate of nervous or putrid fevers with great 
profpedt of fuccefs ? 
V. The defeat of the momentum of the particles of the circu- 
lating blood is another caufe of the quiefcence, with which the 
cold fits of fever commence. This ftimulus of the momentum 
of the progreflive particles of the blood does not aft over the 
whole body like thofe of heat and diftention above defcribed, 
but is confined to the arterial fyftem; and differs from the 
ftimulus of the diftention of the blood, as much as the vibra- 
tion of the air does from the currents of it. Thus are the dif- 
ferent organs of our bodies ftimulated by four different mechan- 
ic properties of the external world : the fenfe of touch by the 
preflure of folid bodies fo as to diftinguilh their figure ; the 
mufcular fyftem by the diftention, which they occafion ; the in- 
ternal furface of the arteries, by the momentum of their moving 
particles; and the auditory nerves, by the vibration of them : 
and 292 
DISEASES 
Sect. XXXII. 5. 2. 
and thefe four mechanic properties are as different from each 
other as the various chemical ones, which are adapted to the 
numerous glands, and to the other organs of fenfe. 
2. The momentum of the progreffive particles of blood is 
compounded of their velocity and their quantity of matter: hence 
whatever circumftances diminifh either of thefe without propor- 
tionally increaling the other, and without fuperadding either of 
the general ftimuli of heat or diftention, will tend to produce a 
quiefcence of the arterial fyftem, and from thence of all the 
other irritative motions, which are connected with it. 
Hence in all thofe conftitutions or difeafes where the blood 
contains a greater proportion of ferum, which is the lighted part 
of its compofition, the pulfations of the arteries are weaker, as in 
nervous fevers, chlorofis, and hyfteric complaints; for in thefe 
cafes the momentum of the progreffive particles of blood is lefs ; 
and hence, where the denfer parts of its compofition abound, as 
the red part of it, or the coagulable lymph, the arterial pulfations 
are ftronger ; as in thofe of robuft health, and in inflammatory 
difeafes. 
That this ftimulus of the momentum of the particles of the 
circulating fluid is of the greateft confequence to the arterial 
action, appears from the experiment of injecting air into the 
blood veffels, which feems to deftroy animal life from the 
want of this ftimulus of momentum ; for the diftention of the 
arteries is not diminifhed by it, it poflefles no corrofive acrimony, 
and is lefs liable to repafs the valves than the blood itfelf; fince 
air-valves in all machinery require much lefs accuracy of con- 
ftrudlion than thofe which are oppofed to water. 
3. One method of increafing the velocity of the blood, and in 
confequence the momentum of its particles, is by the exercife 
of the body, or by the friftion of its furface ; fo, on the contra- 
ry, too great indolence contributes to decreafe this ftimulus of 
the momentum of the particles of the circulating blood, and thus 
tends to induce quiefcence; as is feen in hyfteric cafes, and 
chlorofis, and the other difeafes of fedentary people. 
4. The velocity of the particles of the blood in certain cir- 
cumftances is increafed by venefe&ion, which, by removing a 
part of it, diminifhes the refiftance to the motion of the other 
part, and hence the momentum of the particles of it is increaf- 
ed. This may be eafily underftood by confidering it in the ex- 
treme, fince, if the refiftance was greatly increafed, fo as to over- 
come the propelling power, there could be no velocity, and in 
confequence no momentum at all. From this circumftance 
arifes that curious phenomenon, the truth of which I have been 
more than once witnefs to, that venefe&ion will often inftanta- 
neoufly Sect. XXXII. 6. 1. 
OF IRRITATION. 
293 
neoufly relieve thofe nervous pains, which attend the cold peri- 
ods of hyfteric, afthmatic, or epileptic difeafes ; and that even 
where large dofes of opium have been in vain exhibited. In 
thefe cafes the pulfe becomes ftronger after the bleeding, and 
the extremities regain their natural warmth ; and an opiate then 
given aCts with much more certain effect. 
VI. There is another caufe, which teems occafionally to in- 
duce quiefcence into fome part of our fyftem, I mean the influ- 
ence of the fun and moon; the attraction of thefe luminaries, 
by decreafing the gravity of the particles of the blood, cannot af- 
feCt their momentum, as their vis inertiae remains the fame; 
but it may neverthelefs produce fome chemical change in them, 
becaufe whatever affeCts the general attractions of the particles 
of matter may be fuppofed from analogy to affect their fpecific 
attractions or affinities : and thus the ftimulus of the particles 
of blood may be diminiffied, though not their momentum. As 
the tides of the fea obey the fouthing and northing of the moon 
(allowing for the time neceffary for their motion, and the ob- 
ItruCtions of the fhores), it is probable, that there are alfo at- 
mofpheric tides on both Tides of the earth, which to the inhab- 
itants of another planet might fo defied the light as to refemble 
the ring of Saturn. Now as thefe tides of water, or of air, are 
xaifed by the diminution of their gravity, it follows, that thek 
preflure on the furface of the earth is no greater than the preflure 
of the other parts of the ocean, or of the atmofphere, where no 
fuch tides exift ; and therefore that they cannot affeft the mer- 
cury in the barometer. In the fame manner, the gravity of all 
other terreftrial bodies is diminiffied at the times of the fouth- 
ing and northing of the moon, and that in a greater degree when 
this coincides with the fouthing and northing of the fun, and 
this in a ftill greater degree about the times of the equinoxes. 
This decreafe of the gravity of all bodies during the time the 
moon paffes our zenith or nadir might poffibly be (hewn by the 
flower vibrations of a pendulum, compared with a fpring clock, 
or with aftronomical obfervation. Since a pendulum of a cer- 
tain length moves flower at the line than near the poles, becaufe 
the gravity being diminiffied and the vis inertix continuing the 
fame, the motive power is lefs, but the refillanceto be overcome 
continues the fame. The combined powers of the lunar and 
folar attraction are eftimated by Sir Ifaac Newton not to exceed 
one 7,868,850th part of the power of gravitation, which feems 
indeed but a fmall circumftance to produce any confiderable ef- 
feCt on the weight of fublunary bodies, and yet this is fufficient 
to raife the tides at the equator above ten feet high; and if it be 
confidered, what fmall impulfes of other bodies produce their 
effeCts 294 
DISEASES 
Sect. XXXII. 6. r. 
effects on the organs of fenfe adapted to the perception of them, 
as of vibration on the auditory nerves, we (hall ceafe to be fur- 
prifed, that fo minute A diminution in the gravity of the parti- 
cles of blood Ihould fo far affedt their chemical changes, or their 
Simulating quality, as, joined with other caufes, fometimes to 
produce the beginnings of difeafes. 
Add to this, that if the lunar influence produces a very fmall 
degree of quiefcence at firft, and if that recurs at certain peri- 
ods even with lefs power to produce quiefcence than at firft, yet 
the quiefcence will daily increafe by the acquired habit acting 
at the fame time, till at length fo great a degree of quiefcence is 
induced as to produce phrenfy, canine madnefs, epilepfy, hyfter- 
ic pains or cold fits of fever, inftances of many of which are to 
be found in Dr. Mead's work on this fubjeft. The folar influ- 
ence alfo appears daily in feveral difeafes ; but as darknefs, fi- 
Jence, fleep, and our periodical meals mark the parts of the fo- 
lar circle of actions, it is fometimes dubious to which of thefe 
the periodical returns of thefe difeafes are to be afcribed. 
As far as I have been able to obferve, the periods of inflam- 
matory difeafes obferve the folar day; as the gout and rheuma- 
tifm have their greateft quiefcence about noon and midnight, 
and their exacerbations fome hours after; as they have more 
frequently their immediate caufe from cold air, inanition, or fa- 
tigue, than from the effects of lunations: whilft the cold fits of 
hvfteric patients, and thofe in nervous fevers, more frequently 
occur twice a day, later by near half an hour each time, accord- 
ing to the lunar day ; whilft fome fits of intermittents, which 
are undifturbed by medicines, return at regular folar periods, 
and others at lunar ones ; which may, probably, be owing to the 
difference of the periods of thofe external circumftances of cold, 
inanition, or lunation, which immediately caufed them. 
We muft, however, obferve, that the periods of quiefcence 
and exacerbation in difeafes do not always commence at the times 
of the fyzygies or quadratures of the moon and fun, or at the 
times of their palling the zenith or nadir ; but as it is probable, 
that the ftimulus of the particles of the circumfluent blood is 
gradually diminilhed from the time of the quadratures to that of 
the fyzygies, the quiefcence may commence at any hour, when 
co-operating with other caufes of quiefcence, it becomes great 
enough to produce a difeafe : afterwards it will continue to re- 
cur at the fame period of the lunar or folar influence ; the fame 
caufe operating conjointly with the acquired habit, that is with 
the catenation of this new motion with the diffevered links of 
the lunar or folar circles of animal aftion. 
In this manner the periods of menftruafion obey the lunar 
month Sect. XXXII. 7. 1. 
OF IRRITATION. 
295 
month with great exa&nefs in healthy patients (and perhaps the 
venereal orgafm in brute animals does the fame), yet thefe pe- 
riods do not commence either at the fyzygies or quadratures of 
the lunations, but at whatever time of the lunar periods they be- 
gin, they obferve the fame in their returns till feme greater 
caufe difturbs them. 
Hence, though the bell way to calculate the time of the ex- 
pected returns of the paroxyfms of periodical difeafes is to count 
the number of hours between the commencement of the two 
preceding fits, yet the following obfervations may be worth at- 
tending to, when we endeavour to prevent the returns of maniac- 
al or epileptic difeafes ; whole periods (at the beginning of them 
efpecially) frequently obferve the fyzygies of the moon and fun, 
and particularly about the equinox. 
The greatell of the two tides happening in every revolution 
of the moon, is that when the moon approaches neareft to the 
zenith or nadir; for this reafon, while the fun is in the northern 
figns, that is during the vernal and fummer months, the greater 
of the two diurnal tides in our latitude is that, when the moon 
is above the horizon ; and when the fun is in the fouthern figns, 
or during the autumnal and winter months, the greater tide is 
that, which arifes when the moon is below the horizon ; and 
as the fun approaches fomewhat nearer the earth in winter than 
in fummer, the greatell equinoctial tides are obferved to be a lit- 
tle before the vernal equinox, and a little after the autumnal one. 
Do not the cold periods of lunar difeafes commence a few 
hours before the fouthing of the moon during the vernal and 
fummer months, and before the northing of the moon during 
the autumnal and winter months ? Do not palfies and apoplex- 
ies, which occur about the equinoxes, happen a few days before 
the vernal equinoctial lunation, and after the autumnal one ? 
Are not the periods of thofe diurnal difeafes more obflinate, 
that commence many hours before the fouthing or northing of 
the moon, than of thofe which commence at thofe times ? Are 
not thofe palfies and apoplexies more dangerous which com- 
mence many days before the fyzygies of the moon, than thofe 
which happen at thofe times ? See Secfl. XXXVI. on the peri- 
ods of difeafes. 
VII. Another very frequent caufe of the cold fit of fever is 
the quiefcence of fome of thofe large congeries of glands, which 
compofe the liver, fpleen, or pancreas ; one or more of which 
are frequently fo enlarged in the autumnal intermittents as to 
be perceptible to the touch externally, and are called by the vul- 
gar ague-cakes. As thefe glands are llimulated into acflion by 
the fpecific pungency of the fluids, which they abforb, the gener- 
- > al 296 
DISEASES 
Sect. XXXII. 8. r. 
al caufe of their quiefcence feems to be too great infipidity of 
the fluids of the body, co-operating perhaps at the fame time 
with other general caufes of quiefcence. 
Hence, in marffiy countries at cold feafons, which have fuc- 
ceeded hot ones, and amonglt thofe, who have lived on innutri- 
tions and unftimulating diet, thefe agues are moft frequent. 
The enlargement of thefe quiefcent vifcera, and the fwelling of 
the praecordia in many other fevers, is, moft probably, owing to 
the fame caufe ; which may confift in a general deficiency of 
the production of fenforial power, as well as in the diminiftied 
ftimulation of the fluids ; and when the quiefcence of fo great 
a number of glands, as conftitute one of thofe large vifcera, 
commences, all the other irritative motions are affeCted by their 
connexion with it, and the cold fit of fever is produced. 
VIII. There are many other caufes, which produce quiefcence 
of fome part of the animal fyftem, as fatigue, hunger, thirft, bad 
diet, disappointed love, unwholefome air, exhauftion from evacu- 
ations, and many others ; but the laft caufe, that we Ihall men- 
tion, as frequently productive of cold fits of fever, is fear or 
anxiety of mind. The pains, which we are firft and moft gen- 
erally acquainted with, have been produced by defeCt of fome 
ftimulus ; thus, foon after our nativity we become acquainted 
with the pain from the coldnefs of the air, from the want of 
refpiration, and from the want of food. Now all thefe pains 
occafioned by defeCt of ftimulus are attended with quiefcence of 
the organ, and at the fame time with a greater or lefs degree of 
quiefcence of other parts of the fyftem : thus, if we even en- 
dure the pain of hunger fo as to mifs one meal inftead of our 
daily habit of repletion, not only the periftaltic motions of the 
ftomach and bowels are diminiftied, but we are more liable to 
coldnefs of our extremities, as of our nofes, and ears, and feet, 
than at other times- 
Now, as fear is originally excited by our having experienced 
pain, and is itfelf a painful affeCtion, the fame quiefcence of 
other fibrous motions accompanies it, as has been moft frequent- 
ly conneCled with this kind of pain, as explained in SeCl. XVI. 
S. i. as the coldnefs and palenefs of the fkin, trembling, difficult 
refpiration, indigeftion, and other fymptoms, which contribute 
to form the cold fit of fevers. Anxiety is fear continued through 
a longer time, and, by producing chronical torpor of the fyftem, 
extinguiffies life (lowly, by what is commonly termed a broken 
heart. 
IX. i. We now ftep forwards to confider the other fymp- 
toms in confequence of the quiefcence which begins the fits of 
fever. If by any of the circumftances before defcribed, or by 
two Sect. XXXII. 9. 1. 
OF IRRITATION. 
297 
two or more of them a£Hng at the fame time, a great degree of 
quiefcence is induced on any confiderable part of the circle of 
irritative motions, the whole clafs of them is more or lefs dif- 
turbed by their irritative aflbciations. If this torpor be occa- 
fioned by a deficient fupply of fenforia! power, and happens to 
any of thofe parts of the fyftem, which are accuftomed to per- 
petual a&ivity, as the vital motions, the torpor increafes rapidly, 
becaufe of the great expenditure of fenforial power by the in- 
ceflant activity of thofe parts of the fyftem, as ihewn in No. 3. 
2. of this Section. Hence a deficiency of all the fecretions fuc- 
ceeds, and as animal heat is produced in proportion to the quan- 
tity of thofe fecretions, the eoldnefs of the (kin is the firft cir- 
cumftance, which is attended to. Dr. Martin aflerts, that fome 
parts of his body were warmer than natural in the cold fit of 
fever; but it is certain, that thofe, which are uncovered, as the 
fingers, and nofe, and ears, are much colder to the touch, and 
paler in appearance. It is pofiible, that his experiments were 
made at the beginning of the fubfequent hot fits ; w'hich com- 
mence with partial distributions of heat, owing to fome parts of 
the body regaining their natural irritability fooner than others. 
From the quiefcence of the anaftomofing capillaries a pale- 
nefs of the ficin fucceeds, and a lefs fecretion of the perfpirable 
matter ; from the quiefcence of the pulmonary capillaries a dif- 
ficulty of refpiration arifes; and from the quiefcence of the oth- 
er glands lefs bile, lefs gaftric and pancreatic juice, are fecreted 
into the ftomach and inteftines, and lefs mucus and faliva are 
poured into the mouth; whence arifes the dry tongue, coftive- 
nefs, dry ulcers, and paucity of urine. From the quiefcence of 
the abforbent fyftem arifes the great thirft, as lefs moifture is ab- 
forbed from the atmofphere. The abforption from the atmof- 
phere was obferved by Dr. Lifter to amount to eighteen ounces 
in one night, above what he had at the fame time infenfibly per- 
fpired. See Langrifh. On the fame account the urine is pale, 
though in fmall quantity, for the thinner part is not abforbed 
from it; and when repeated ague-fits continue long, the legs 
fwell from the diminifhed abforption of the cellular abforbents. 
From the quiefcence of the inteftinal canal a lofs of appetite 
and flatulencies proceed. From the partial quiefcence of the 
glandular vifcera a fwelling and tenfion about the praecordia be- 
come fenfible to the touch ; which are occafioned by the delay 
of the fluids from the defeat of venous or lymphatic abforption. 
The pain of the forehead, and of the limbs, and of the fmall of 
the back, arifes from the quiefcence of the membranous fafcia, 
or mufcles of thofe parts, in the fame manner as the fkin be- 
comes painful, when the veflels, of which it is compofed, be- 
Vol. I. Pf come 298 
DISEASES 
Sect. XXXII. 9. 2, 
come quiefcent from cold. The trembling in confequence of 
the pain of coldnefs, the reftleflhefs, and the yawning, and 
ftretching cf the limbs, together with the fhuddering, or rigors, 
are convulfive motions ; and will be explained amongft the dif- 
eafes of volition ; Sedl. XXXIV. 
Sicknefs and vomiting are a frequent fymptom in the begin- 
nings of fever-fits, the mufcular fibres of the ftomach ihare the 
general torpor and debility of the fyftem ; their motions become 
firft leflened, and flop, and then become retrograde; for the act of 
vomiting, like the globus hyftericus and the borborigmi of hypo- 
chondiiafis, is always a fymptom of debility, either from want of 
ftimulus, as in hunger ; or from want of fenforial power, as af- 
ter intoxication; or from fympathy with feme other torpid ir- 
ritative motions, as in the cold fits of ague. See Sect. XII. 5. 
5. XXIX. 11. and XXXV. 1.3. where this act of vomiting is 
further explained. 
The fmall pulfe, which is faid by fome writers to be flow at 
the commencement of ague-fits, and which is frequently trem- 
bling and intermittent, is owing to the quiefcence of the heart 
and arterial fyftem, and to the refiftance oppofed to the circu- 
lating fluid from the inactivity of all the glands and capillaries. 
The great weaknefs and inability to voluntary motions, with the 
infenfibility of the extremities, are owing to the general quief- 
cence of the whole moving fyftem ; or, perhaps, limply to the 
deficient production of fenforial power. 
If all thefe fymptoms are further increafed, the quiefcence of 
all the mufcles, including the heart and arteries, becomes com- 
plete, and death enfues. This is, moft probably, the cafe of 
thofe who are ftarved to death with cold, and of thofe who are 
faid to die in Holland from long Ikating on their frozen canals. 
2. As foon as this general quiefcence of the fyftem ceafes, 
either by the diminution of the caufe, or by the accumulation of 
fenforial power, (as in fyncope, Sedt. XII. 7. 1.) which is the 
natural confequence of previous quiefcence, the hot fit com- 
mences. Every gland of the body is now ftimulated into 
ftronger aCtion than is natural, as its irritability is increafed by 
accumulation of fenforial power during its late quiefcence, a fu- 
perabundance of all the fecretions is produced, and an increafe 
of heat in confequence of the increafe of thefe fecretions. The 
fkin bccotnes red, and the perfpiration great, owing to the in- 
creafed action of the capillaries during the hot part of the par- 
oxyfm. The fecretion of perfpirable matter is perhaps greater 
during the hot fit than in the fweating fit which follows ; but 
as the abforption of it alio is greater, it does not ftand on the 
fkin in vifiblc drops : add to this, that the evaporation of it alfo 
is Sect. XXXII. 9. 2. 
OF IRRITATION. 
299 
is greater, from the increafed heat of the ikin. But at the de- 
cline of the hot fit, as the mouths of the abforbents of the Ikin 
are expofed to the cooler air, or bed-clothes, thefe vefiels fooner 
lofe their increafed activity, and ceafe to abforb more than their 
natural quantity : but the fecerning vefiels for feme time longer, 
being kept warm by the circulating blood, continue to pour out 
an increafed quantity of perfpirable matter, which now Hands 
cn the ikin in large vifible drops ; the exhalation of it allo being 
leflened by the greater coolncfs of the Ikin, as well as its abforp- 
tion by the diminiflied action of the lymphatics. See Clals I. 
I- 2. 3. 
The increafed fecretion of bile and of other fluids poured in- 
to the inteftines frequently induces a purging at the decline of 
the hot fit; for as the external abforbent vefiels have their 
mouths expofed to the cold air, as above mentioned, they ceafe 
to be excited into unnatural activity fooner than the fecretory 
vefiels, whofe mouths are expofed to the warmth of the blood : 
now, as the internal abforbents fympathize with the external 
ones, thefe alfo, which during the hot fit drank up the thinner 
part of the bile, or of other fecreted fluids, lofe their increafed 
activity before the gland lofes its increafed activity, at the de- 
cline of the hot fit;' and the loofe dejections' are produced from 
the fame caufe, that the increafed perfpiration Hands on the fur- 
face of the Ikin, from the increafed abforption ceafing fooner 
than the increafed fecretion. 
The urine during the cold fit is in fmall quantity and pale, 
both from a deficiency of the fecretion and a deficiency of the 
abforption. During the hot fit it is in its ufual quantity, but 
very high coloured and turbid, becaufe a greater quantity had 
been fecreted by the increafed adlion of the kidneys, and alfo a 
greater quantity of its more aqueous part had been abforbed from 
it in the bladder by the increafed adtion of the abforbents ; and 
laHly, at the decline of the hot fit it is in large quantity and lefs 
coloured, or turbid, becaufe the abforbent vefiels of the bladder, 
as obferved above, lofe their increafed adlion by fympathy with 
the cutaneous ones fooner than the fecretory vefiels of the kid- 
neys lofe their increafed activity. Hence the quantity of the fedi- 
ment, and the colour of the urine, in fevers, depend much on the 
quantity fecreted by the kidneys, and the quantity abforbed from 
it again in the bladder : the kinds of fediment, as the lateritious, 
purulent, mucous, or bloody fediments, depend on other caufes. 
It fhould be obferved, that if the fweating be increafed by the 
heat of the room, or of the bed-clothes, a paucity of turbid urine 
will continue to be produced, as the abforbents of the bladder 
will have their adbivity increafed by their fympathy with the 
yeflel? 300 
DISEASES 
Sect. XXXII. 9. 3. 
veflels of the {kin, for the purpofe of flipplying the fluid expend- 
ed in perfpiration. 
The pulfe becomes ftrong and full, owing to the increafed ir- 
ritability of the heart and arteries, from the accumulation of fcn- 
forial power during their quiefcence, and to the quickness of 
the return of the blood from the various glands and capillaries. 
This increafed action of all the fecretory veflels does not occur 
very fuddenly, nor univerfally at the fame time. The heat feems 
to begin about the centre, and to be diffufed from thence irregu- 
larly to the other parts of the fyftem. This may be owing to 
the fituation of the parts which firft became quiefcent and caufed 
the fever-fit, efpecially when a hardnefs or tumour about the 
praecordia can be felt by the hand ; and hence this part, in 
"whatever vifcus it is feated, might be the firft to regain its nat- 
ural or increafed irritability. 
3. It muft be here noted, that, by the increafed quantity of 
heat, and of the impulfe of the blood at the commencement of 
the hot fit, a great increafe of ftimulus is induced, and is now 
added to the increafed irritability of the fyftem, which was oc- 
cafioned by its previous quiefcence. This additional ftimulus 
of heat and momentum of the blood augments the violence of 
the movements of the arterial and glandular fyftem in an in- 
creafing ratio. Thefe violent exertions ft ill producing more 
heat and greater momentum of the moving fluids, till at length 
the fenforial power becomes wafted by this great ftimulus be- 
neath its natural quantity, and predifpofes the fyftem to a fec- 
ond cold fit. 
At length all thefe unnatural exertions fpontaneoufly fubfide 
with the increafed irritability that produced them ; and which 
was itfelf produced by the preceding quiefcence, in the fame 
manner as the eye, on coming from darknefs into day-light, in 
a little time ceafes to be dazzled and pained-, and gradually re- 
covers its natural degree of irritability. 
4. But if the increafe of irritability, and the confequent in- 
creafe of the ftimulus of heat and momentum, produce more 
violent exertions than thofe above dcfcribed ; great pain arifes 
in fome part of the moving fyftem, as in the membranes of the 
brain, pleura, or joints ; and new motions, of the veflels are pro- 
duced in confequence of this pain, which are called inflamma- 
tion ; or delirium or ftnpor arifes ; as explained in Sedt. XXL 
and XXXIII.: for the immediate effect is the fame, whether 
the great energy of the moving organs arifes from an increafe of 
ftimulus or an increafe of irritability ; though in the former cafe 
the wafte of fenforial power lcad& to debility, and in the latter 
to health. 
Recapitulation. Sect. XXXII. 10. 1. 
OF IRRITATION. 
301 
Recapitulation. 
X. Thofe mufcles, which are lefe frequently exerted, and 
whofe actions are interrupted by fleep, acquire lefs accumulation 
of fenforial power during their quicfcent ftate, as the mufcles 
of locomotion. In thefe mufcles after great exertion, that is, 
after great exhauftion of the fenforial power, the pain of fatigue 
enfues 5 and during reft there is a renovation of the natural 
quantity of fenforial power ; but where the reft, or quiefcence 
of the mufck, is long continued, a quantity of fenforial power 
becomes accumulated beyond what is necelfary; as appears by 
the uneabnv.K occafioned by want of exercife; and which in 
young an mils is one caufe exciting them into action, as is feen 
in the play of puppies and kittens. 
But when thofe mufcles, which are habituated to perpetual 
actions, as thofe of the ftomach by the ftimulus of food, thofe 
of the vell'els of the fkinby the ftimulus of heat, and thofe which 
conftitute the arteries and glands by the ftimulus of the blood, 
become for a time quiefcent, from the want of their appropria- 
ted ftimuli, or by their aflbciations with other quiefcent parts of 
the fyftem ; a greater accumulation of fenforial power is ac- 
quired during their quiefcence, and a greater or quicker ex- 
hauftion of it is produced during their increafed action. 
This accumulation of fenforial power from deficient action, 
if it happens to the ftomach from want of food, occafions the 
pain of hunger ; if it happens to the vefiels of the Ikin from 
want of heat, it occafions the pain of cold ; and if to the arterial 
fyftem from the want of its adapted ftimuli, many difagreeable 
fenfations are occafioned, fuch as are experienced in the cold fits 
of intermittent fevers, and are as various, as there are glands or 
membranes in the fyftem, and are generally termed univerfal 
uneafinefs. 
When the quiefcence of the arterial fyftem is not owing to de- 
feat of ftimulus as above, but to the defective quantity of fcnfo- 
rial power, as in the commencement of nervous fever, or irrita- 
tive fever with weak pulfe, a great torpor of this fyftem is 
quickly induced ; becaufe both the irritation from the ftimulus 
of the blood, and the afibciation of the vafcular motions with 
each other, continue to excite the arteries into action, and thence 
quickly exhauft the ill-fupplied vafcular mufcles; for to reft 
is death; and therefore thole vafcular mufcles continue to pro- 
ceed, though with feebler action, to the extreme of wearinefs 
or faintnefs: while nothing fimilar to this affects the locomo- 
tive mufcles, whofe actions are generally caufed by volition, and 
not 302 
DISEASES 
Sect. XXXII. io. r, 
not much fubjcdt either to irritation or to other kinds of aflb- 
ciations bcfides the voluntary ones, except indeed when they 
are excited by the 1 afh of flavery. 
In theie vafcular mufcles, which are fubjedt to perpetual ac- 
tion, and thence liable to great accumulation of fenforial power 
during their quiefcence from want of ftimulus, a great increafe 
of activity occurs, either from the renewal of their accuftomed 
ftimulus, or even from much lefs quantities of ftimulus than ufu-r 
al. This increafe of adlion conftitutes the hot fit of fever, 
which is attended with various increafed fecretions, with great 
concomitant heat, and general uneafinefs. The uneafinefs at- 
tending this hot paroxyfm of fever, or fit of exertion, is very dif- 
ferent from that, which attends the previous cold fit, or fit of 
quiefcence, and is frequently the caufe of inflammation, as in 
pleurify, which is treated of in the next fedtion. 
A fimilar effedt occurs after the quiefcence of our organs of 
fenfe; thofe which are not fubjedl to perpetual adlion, as the 
tafte and fmell, are lefs liable to an exuberant accumulation of 
fenforial power after their having for a time been inadtive ; but 
the eye, which is in perpetual adiion during the day, becomes 
dazzled, and liable to inflammation after a temporary quiefcence. 
Where the previous quiefcence has been owing to a defedt of 
fenforial power, and not to a defedt of ftimulus, as in the irrita- 
tive fever with weak pulfe, a fimilar increafe of activity of the 
arterial fyftem fucceeds, either from the ufual ftimulus of the 
blood, or from a ftimulus lefs than ufual; but as there is in 
general in thefe cafes of fever with weak pulfe a deficiency of 
the quantity of the blood, the pulfe in the hot fit is weaker than 
in health, though it is ftronger than in the cold fit, as explained 
in No. 2. of this fedtion. But at the fame time in thofe fevers, 
where the defect of irritation is owing to the defect of the 
quantity of fenforial power, as well as to the defect of ftimulus, 
another circumftance occurs ; which confifts in the partial dif- 
tribution of it, as appears in partial flulhings, as of the face or 
bofom, while the extremities are cold; and in the increafe of 
particular fecretions, as of bile, faliva, infenfible perfpiraticn, 
with great heat of the Ikin, or with partial fweats, or diarrhoea. 
There are alfo many uneafy fenfations attending thefe in- 
creafed adtions, which like thofe belonging to the hot fit of fe- 
ver with ftrong pulfe, are frequently followed by inflammation, 
as in fcarlet fever ; which inflammation is neverthelefs accom- 
panied with a pulfe weaker, though quicker, than the pulfe dur 
ring the remiffion or intermifiion of the paroxyfms, though 
ftronger than that of the previous cold fit. , 
From hence 1 conclude, that both the cold and hot fits of fe- 
ver Sect. XXXII. n. i. 
OF IRRITATION. 
303 
ver are neceflary confequences of the perpetual and inceffant 
a&ion of the arterial and glandular fyftem ; fince thofe mufcu- 
lar fibres and thofe organs of feme, which are moll frequently 
exerted, become necefl'arily mofi affected both with defect and. 
accumulation of fenforial power : and that hence fever-fits are 
not an effort of nature to relieve herjelf and that therefore they 
lliould always be prevented or diminilhed as much as poflible, 
by any means which decreafe the general or partial vafcular ac- 
tions, when they are greater, or by increafmg them when they 
are lefs than in health, as defcribed in Sedt. XII. 6. i. 
Thus have I endeavoured to explain, and I hope to the fatis- 
faction of the candid and patient reader, the principal fymp- 
toms or circumflances of fever without the introduction of the 
fupernatural power of fpafm. To the arguments in favour of 
the doctrine of fpafm it may be fuflicient to reply, that in the 
evolution of medical as well as of dramatic cataftrophe, 
Nec Deus interfit, nifi dignus vindice nodus 
Incident. Hor. 
XL i. Since I pi inted the above in the firft edition of this 
work, I am told, that the fpafmodic doctrine of fever has yet its 
advocates ; who believe that the coldnefs at the beginning of in- 
termittent fevers is owing to a fpafm of the cutaneous veflels. 
But as the ikin is at that time lax and foft, the mufcular fibres 
of thofe cutaneous veflels cannot be in action or contraction, 
which conftitute fpafm. Whence we have the evidence both 
of our fight and touch againft this wild imagination. 
Others have advanced, that this fpafmodic contraction of the 
cutaneous veflels or pores confines the heat, or drives it to the 
heart; which in the hot fit of fever repels the heat again to the 
Ikin by its readlion. Thofe, who efpoufe this dodlrine, feem to 
conceive, that the particles of heat are as large as Ihot-corns, or 
as the globules of blood ; and not that it is an ethereal fluid, in 
which all things are immerfed, and by which all things are 
penetrated ; an opinion which originated from Galen, and muft 
have been founded on a total ignorance of chemiftry, and natu- 
ral philofophy. Others, I hear, Hill fuppofe cold to be a flimu- 
lus, not underllanding that it is fimply the abfence of heat; and 
that darknefs might as well be called a Him ulus to the eye, or 
hunger a Ilimulus to the Itomach, as cold to our fenfe, which 
perceives heat ; which is commonly confounded with our fenfe 
of touch, which perceives figure. The pain, which we experi- 
ence on being expofed to a want of heat, which is termed chill- 
nefs, or coldnefs ; and the pain we experience in our organs of 
digellion 304 
DISEASES 
Sect. XXXII. n. i. 
digeftion from the want of food, which is termed hunger; both 
arife from the inactivity of thofe veflels, which ought to be either 
perpetually, or at periodical times ftimulated into action. See 
Sett. XIII. 3. 2. And the {hivering or actions of the fubcuta- 
neous mufcles, when we are cold, are in confequence of the 
pain, or voluntary exertion to relieve that pain, and originate 
from the want of ftimulus, not from the excefs of it. 
In this age of reafon it is not the opinions of others, but the 
natural phenomena, on which thofe opinions are founded, 
which deferve to be canvafled. And with the fuppofed exift- 
ence of ghofts or apparitions, witchcraft, vampyrifin, aftrology, 
animal magnetifm, and American tradlors, fuch theories as the 
above muft vanilh like the fcenery of a dream ; as they confift 
of fuch combinations of ideas, as have no prototype or corref- 
pondent combinations of material objects exilting in nature. 
SECT. Sect. XXXIII. i. i. 
OF SENSATION. 
305 
SECT. XXXIII. 
DISEASES OF SENSATION. 
I. I. Motions excited by fenfation. Digeftion. Generation. Pleaf- 
ure of txiftence. Hypochondriacifm. 2. Pain introduced. Sen- 
fitive fevers of two kinds. 3. Two fenforial powers exerted in 
fenfitive fevers. Size of the blood. Nervous fevers dijlinguifhed 
from putrid ones. The feptic and antifeptic theory. 4. Two 
kinds of delirium. 5. Other animals are lefs liable to delirium, 
cannot receive our contagious difeafes, and are lefs liable to madnefs. 
II. 1. Senfttive motions generated. 2. Inflammation explained. 
3. Its remote caufes from excefs of irritation, or of irritability, not 
from thofe pains which are owing to defeat of irritation. New vef- 
fels produced, and much heat. 4. Purulent matter fecreted. 5. Con- 
tagion explained. 6. Received but once. If common matter 
be contagious ? 8. T^hy fame contagions are received but once. 9. 
Why others may be received frequently. Contagions of fmall-pox 
and meaftes do not aft at the fame time. Two cafes of fuch pa- 
tients. 1 o. The blood from patients in the fmall-pox will not in- 
fecl others. Cafes of children thus inoculated. The variolous con- 
tagion is not received into the blood. It alls by fenfitive affectation 
between theJlomach andfkin. III. 1. Abferptioti of folids and 
fluids. 2. Art of healing ulcers. 3. Mortification attended 
with lefs pain in weak people. 
I. i. As many motions of the body are excited and continu- 
ed by irritations, fo others require, either conjun&ly with thefe, 
or feparately, the pleafurable or painful fenfations, for the pur- 
pofe of producing them with due energy. Amongft thefe the 
bufinefs of digeftion fupplies us with an inftance : if the food, 
which we fwallow, is not attended with agreeable fenfation, it 
digefts lefs perfectly; and if very difagreeable fenfation accom- 
panies it, fuch as a naufeous idea, or very difguftful tafte, the 
digeftion becomes impeded ; or retrograde motions of the ftom- 
ach and cefophagus fucceed, and the food is ejected. 
The bufinefs of generation depends fo much on agreeable fen- 
fation, that, where the objetSI is difguftful, neither voluntary ex- 
ertion nor irritation can effect the purpofe ; which is alfo liable 
to be interrupted by the pain of fear or-bafhfulnefs. 
Befidcs the pleafure, which attends the irritations produced by 
the objects of luft and hunger, there feems to be a fum of pleaf- 
urable affection accompanying the various fecretions of the nu- 
merous glands, which conftitute the pleafure of life, in contradif- 
Vol. I. Q» < tindion 306 
DISEASES 
Sect. XXXIII. i. 2, 
tinCfion to the tedium vitse. This quantity or fum of pleafura* 
ble affection feems to contribute to the due or energetic per-* 
formance of the whole moveable fyftem, as well that of the heart 
and arteries, as of digeftion and of abforption; fince without 
the due quantity of pleafurable fenfation, flatulency and hypo- 
chondriacifm affect the inteftines, and a languor feizes the arte- 
rial pulfations and fecretions ; as occurs in great and continued 
anxiety of the mind. 
2. Befides the febrile motions occafioned by irritation, de- 
fcribed in SeCt. XXXII. and termed irritative fever, it frequent- 
ly happens that pain is excited by the violence of the fibrous 
contractions ; and other new motions are then fuperadded, in 
confequence of fenfation, which we (hall term febris fenfitiva, 
or fenfitive fever. It mufl be obferved, that moft irritative fe- 
vers begin with a decreafed exertion of irritation, owing to de- 
fe£t of ftimulus; but that on the contrary the fenfitive fevers 
or inflammations, generally begin with the increafed exertion of 
fenfation, as mentioned in SeCt. XXXI. on temperaments : for 
though the cold fit, which introduces inflammation, commences 
with decreafed irritation, yet the inflammation itfelf commences 
in the hot fit during the increafe of fenfation. Thus a common 
puftule, or phlegmon, in a part of little fenfibility does not ex- 
cite an inflammatory fever ; but if the ftomach, inteftines, or 
the tender fubftance beneath the nails, be injured, great fenfa- 
tion is produced, and the whole fyftem is thrown into that kind 
of exertion, which conftitutes inflammation. 
Thefe fenfitive fevers, like the irritative ones, refolve them- 
felves into thofe with arterial ftrength, and thofe with arterial 
debility, that is with excefs or defect of fenforial power ; thefe 
may be termed the febris fenfitiva pulfu forti, fenfitive fever 
with ftrong pulfe, which is the fynocha, or inflammatory fever; 
and the febris fenfitiva pulfu debili, fenfitive fever with weak 
pulfe, which is the typhus gravior, or putrid fever of fome 
writers. 
3. The inflammatory fevers, which are here termed fenfitive 
fevers with ftrong pulfe, are generally attended with fome topical 
inflammation, as pleurify, peripneumony, or rheumatifm, which 
diftinguifhes them from irritative fevers with ftrong pulfe. The 
pulfe is ftrong, quick, and full; for in this fever there is great 
irritation, as well as great fenfation, employed in moving the 
arterial fyftem. The fize, or coagulable lymph, which appears 
on the blood, is probably an increafed fecretion from the in- 
flamed internal lining of the whole arterial fyftem, the thinner 
part being taken away by the increafed abforption of the in- 
flamed lymphatics. 
The Sect. XXXIII. 1.4. 
OF SENSATION. 
307 
The fenfitive fevers with weak pulfe, which are termed putrid 
or malignant fevers, are diftinguilhed from irritative fevers with 
weak pulfe, called nervous fevers, defcribed in the 1aft fection, 
as the former confift of inflammation joined with debility, and 
the latter of debility alone. Hence there is greater heat and 
more florid colour of the (kin in the former, with petechiae, or 
purple fpots, and aphthae, or floughs in the throat, and generally 
with previous contagion. 
When animal matter dies, as a flough in the throat, or the 
mortified part of a carbuncle, if it be kept mbift and warm, as 
during its adhefion to a living body, it will foon putrefy. This 
and the origin of contagion from putrid animal fubftances, feem 
to have given rife to the feptic and antifeptic theory of thefe fevers. 
The matter in puftules and ulcers is thus liable to become 
putrid, and to produce microfcopic animalcula; the urine, if too 
long retained, may alfo gain a putrefeent fmell, as well as the 
alvine feces; but fome writers have gone fo far as to believe, 
that the blood itfelf in thefe fevers has fmelt putrid, when drawn 
from the arm of the patient; but this feems not well founded ; 
fince a fingle particle of putrid matter taken into the blood can 
produce fever, how can we conceive that the whole mafs could 
continue a minute in a putrid ftate without deftroying life ? 
Add to this, that putrid animal fubftances give up air, as in 
gangrenes; and that hence if the blood was putrid, air ihould 
be given out, which in the blood-veflels is known to occafioq, 
immediate death. 
In thefe fenfitive fevers with ftrong pulfe (or inflammations) 
there are two fenforial faculties concerned *in producing the dif- 
eafe, viz. irritation and fenfation; and hence, as their combined 
action is more violent, the general quantity of fenforial power 
becomes further exhaufted during the exacerbation, and the 
fyftem more rapidly weakened than in irritative fever with 
ftrong pulfe ; where the fpirit of animation is weakened by but 
one mode of its exertion : fo that this febris fenfitiva pulfu forti 
(or inflammatory fever) may be confidered as the febris irritativa 
pulfu forti, with the addition of inflammation ; and the febris 
fenfitiva pulfu debili (or malignant fever) may be confidered as 
the febris irritativa pulfu debili (or nervous fever, with the addi- 
tion of inflammation. 
4. In thefe putrid or malignant fevers a deficiency of irrita- 
bility accompanies the increafe of fenfibility ; and by this wafte 
of fenforial power by the excefs of fenfation, which was already 
toofmall, arifes the delirium and ftupor which fo perpetually at- 
tend thefe inflammatory fevers with arterial debility. In thefe 
cafes the voluntary power firft ceafes to atft from deficiency of 
fenforial 308 
DISEASES 
Sect. XXXIII. i. 4. 
fenforial fpirit; and the ftimuli from external bodies have no effed 
on the exhaufted fenforial power, and a delirium like a dream is 
the confequence. At length the internal ftimuli ceafe to excite 
fufficient irritation, and the fecretions are either not produced at 
all, or too parfimonious in quantity. Amongft thefe the fecre- 
tion of the brain, or production of the fenforial power, becomes 
deficient, till atlaft all fenforial power ceafes, except what is juft 
neceflary to perform the vital motions, and a ftupor fucceeds; 
which is thus owing to the fame caufe as the preceding delirium 
exerted in a greater degree. 
This kind of delirium isowing to a fufpenfion of volition, and 
to the difobedience of the fenfes to external ftimuli, and is always 
occafioned by great debility, or paucity of fenforial power; it 
is therefore a bad fign at the end of inflammatory fevers, which 
had previous arterial ftrength, as rheumatifm, or pleurify, as it 
Ihews the prefence of great exhauftion of fenforial power in a 
fyftem, which having lately been expofed to great excitement, is 
not fo liable to be ftimulated into its healthy aClion, either by 
additional ftimulus of food and medicines, or by the accumula- 
tion of fenforial power during its prefent torpor. In inflamma- 
tory fevers with debility, as thofe termed putrid fevers, deliri- 
um is fometimes, as well as ftupor, rather a favourable fign ; as 
lefs fenforial power is wafted during its continuance (fee Clafs 
II. 1. 6. 8.), and the conftitution not having been previoufly ex- 
pofed to excefs of ftimulation, is more liable to be excited after 
previous quiefccnce. 
When the fum of general pleafurable fenfation becomes too 
great, another kind of delirium fupervenes, and the ideas thus 
excited are miftaken for the irritations of external objects : fuch 
a delirium is produced for a time by intoxicating drugs, as fer- 
mented liquors, or opium : a permanent delirium of this kind is 
fometimes induced by the pleafures of inordinate vanity, or by 
the enthufiaftic hopes of heaven. In thefe cafes the power of 
volition is incapable of exertion, and in a great degree the exter- 
nal fenfes become incapable of perceiving their adapted ftimuli, 
becaufe the whole fenforial power is employed or expended on 
the ideas excited by pleafurable fenfation. 
This kind of delirium is diftinguifhed from that which at- 
tends the fevers above mentioned from its not being accompani- 
ed with general debility, but Amply with excefs of pleafurable 
fenfation ; and is therefore in fome meafure allied to madnefs 
or to reverie ; it differs from the delirium of dreams, as in this 
the power of volition is not totally fufpended, nor are the fenfes 
precluded from external ftimulation ; there is therefore a degree 
of confiftencv, in this kind of delirium, and a degree of attention 
tc Sect. XXXIII. 1. 5. 
OF SENSATION. 
309 
to external objects, neither of which exifts in the delirium of 
fevers or in dreams. 
5. It would appear, that the vafcular fyftems of other animals 
are lefs liable to be put into action by their general fum of 
pleafurable or painful fenfation; and that the trains of their 
ideas, and the mufcular motions ufually aflbeiated with them, 
are lefs powerfully connected than in the human fyllem. For 
other animals neither weep, nor fmile, nor laugh ; and are 
hence feldom fubjeCl to delirium, as treated of in Sc6t. XVI. on 
Inftindt. Now as our epidemic and contagious difeafes arc 
probably produced by difagiceable fenfation, and not Pimply by 
irritation ; there appears a reafen why brute animals are lefs 
liable to epidemic or contagious difeafes; andfecondiy, why 
none of our contagions, as the fmali-pcx or mcafles, can be com- 
municated to them, though one of theirs, viz. the hydrophobia, 
as well as many of their poifons, as thofe of fnakes and of in- 
fefts,communicate their deleterous or painful effects to mankind. 
Where the quantity of general painful fenfation is too great 
in the fyftem, inordinate voluntary exertions are produced either 
of our ideas, as in melancholy and madnefs, or of our mufcles, 
as in convulsion. From thefe maladies alfo brute animals arc 
much more exempt than mankind, owing to their greater inapti- 
tude to voluntary exertion, as mentioned in Sedt. XVI.onlnftinCt. 
II. 1. When any moving organ is excited into fuch violent 
motions, that a quantity of pleafurable or painful fenfation is 
produced, it frequently happens (but not always) that new mo- 
tions of the affected organ are generated in confequence of the 
pain or pleafure, which are termed inflammation. 
Thefe new motions are of a peculiar kind, tending to diftend 
the old, and to produce new fibres, and thence to elongate the 
flraight mufcles, which ferve locomotion, and to form new vef- 
fels at the extremities or fidesof the vafcular mufcles. 
2. Thus the pleafurable fenfations produce an enlargement of 
the nipples of nurfes, of the papillae of the tongue, of the penis, 
and probably produce the growth of the body from its embryo1! 
ftate to its maturity ; whilft the new motions in confequence of 
painful fenfation, with the growth of the fibres or veflels, which 
they occafion, are termed inflammation. 
Hence when the ftraight mufcles are inflamed, part of their 
tendons at each extremity gain new life and fenfibility, and thus 
the mufcle is for a time elongated ; and inflamed bones become 
foft, vafcular, and fenfible. Thus new veflels fboot ever the 
cornea of inflamed eyes, and into feirrhous tumours, when they 
become inflamed ; and hence all inflamed parts grow together 
by intermixture, and inofculation of the new and old veflels. 
' The 310 
DISEASES 
Sect. XXXIII. 2. 3. 
The heat is occ-afioned from the increafed fecretions either of 
mucus, or of the fibres, which produce or elongate the veflels. 
The red colour is owing to the pellucidity of the newly formed 
veflels, and as the arterial parts of them are probably formed be- 
fore their correfpondent venous parts. 
3. Thefe new motions are excited either from the increafed 
quantity of fenfation in confequence of greater fibrous contrac- 
tions, or from increafed fenfibility, that is, from the increafed 
quantity of fenfcrial power in the moving organ. Hence they 
are induced by great external ftimuli, as by wounds, broken 
bones ; and by acrid or infectious materials ; or by common 
ftimuli on thofe organs, which have been fome time quiefcent; 
as the ufual light of the day inflames the eyes of thofe, who have 
been confined in dungeons ; and the warmth of a common fire 
inflames thofe, who have been previoufly expofed to much cold. 
But thefe new motions are never generated by that pain, 
which arifes from defect of ftimulus, as from hunger, thirft, 
cold, or inanition, with all thofe pains, which are termed ner- 
vous. Where thefe pains exift, the motions of the affected part 
are lefiened ; and if inflammation fucceeds, it is in fome diftant 
parts; as coughs are caufed by coldnefs and moifture being long- 
applied to the feet; or it is in confequence of the renewal of the 
ftimulus, as of heat or food, which excites our organs into 
ftronger adiion after their temporary quiefcence 5 as kibed heels 
after walking in fnow. 
4. But when thefe new motions of the vafcular mufcles are 
exerted'with greater violence, and thefe veflels are either elonga- 
ted too much or too haftily, a new material is fecreted from their 
extremities, which is of various kinds according to the peculiar 
animal morions of this new kind of gland, which fecretes it; 
fuch is the pus laudabile or common matter, the variolous mat- 
ter, venereal matter, catarrhous matter, and many others. 
5. Thefe matters are the product of an animal procefs; they 
are fecreted or produced from the blood by certain difeafed mo- 
tions of the extremities of the blood-veflels, and are on that ac- 
count all of them contagious ; for if a portion of any of thefe 
is tranfmitted into-the circulation, or perhaps only inferred into 
the ficin, or beneath the cuticle of a healthy perfon, its ftimulus 
in a certain time produces the kune kind of morbid motions, by 
which itfelf was produced ; and hence a fimilar kind is genera- 
ted. See SeT. XXXIX. 6. 1. 
6-. It is remarkable, that many of thefe contagious matters are 
capable of producing a fimilar difeafe but once ; as the fmall- 
pox and mealies ; and I fuppofe this is true of all thofe conta- 
gioos difeafes^ which are fpontauconliy cured by nature in a cer- 
tain Sect. XXXIII. 2. 7. 
OF SENSATION. 
311 
tain time ; for if the body was capable of receiving the difeafe a 
fecond time, the patient muft perpetually infeCt himfelf by the 
very matter, which he has himfelf produced, and is lodged about 
him ; and hence he could never become free from the difeafe. 
Something fimilar to this is feen in the fecondary fever of the 
confluent fmall-pox; there is a great abforption of variolous 
matter, a very minute part of which would give the genuine 
, fmall-pox to another perfon ; but here it only ftimulates the 
fyftem into common fever ; like that which common pus, or 
any other acrid material might occafion. 
7. In the pulmonary confumption, where common matter is 
daily abforbed, an irritative fever only, without new inflam- 
mation, is generally produced ; which is terminated like other 
irritative fevers by fweats or loole (tools. Hence it does not 
appear, that this abforbed matter always aCts as a contagious ma- 
terial producing frefli inflammation or new abfcefles. Though 
there is reafon to believe, that the fir ft time any common matter 
is abforbed, it has this effect, but not the fecond time, like the 
variolous matter above mentioned. 
This accounts for the opinion, that the pulmonary confump- 
tion is fometimes infectious, which opinion was held by the an- 
cients, and continues in Italy at prefent; and I have myfelf feen 
three or four inftances, where a huiband and wife, who have 
flept together, and have thus much received each other's breath, 
who have infected each other, and both died in confequence of 
the original taint of only one of them. This alfo accounts for 
tl\e abfcefles in various parts of the body, that are fometimes 
produced after the inoculated fmall-pox is terminated ; for this 
fecond abforption of variolous matter aCts like common matter, 
and produces only irritative fever in thofe children, whofe confti- 
tutions have already experienced the abforption of common mat- 
ter ; and inflammation with a tendency to produce new abfcefles 
in thofe, whofe conftitutions have not experienced the abforp- 
tions of common matter. 
It is probable* that more certain proofs might have been found 
to fhew, that common matter is infectious the firlt time it is 
abforbed, tending to produce fimilar abfcefles, but not the fec- 
ond time of its abforption, if this fubjeCt had been attended to. 
8. Thefe contagious difeafes are very numerous, as the 
plague, fmall-pox, chicken pox, meafles, fcarlet-fever, pemphi- 
gus, catarrh, chin-cough, venereal difeafe, itch, trichoma, tinea. 
The infectious material does not feem to be diflblved by the air, 
but only mixed with it perhaps in fine powder, which foon fub- 
fides ; fmee many of thefe contagions can only be received by 
actual contaCl; and others of them only at fmall diftances from 
the 312 
DISEASES 
Sect. XXXIII. 2.^ 
the infected nerfon ; aS is evident from many perfons having 
been near patients of the fmall-pox without acquiring the 
difeafe. 
The reafon, why many of thefe difeafes are received but once, 
and others repeatedly, is not well underftood ; it appears to me, 
that the conftitution becomes fo accuftomed to the ftimuli of 
thefe infectious materials, by having once experienced them, 
that though irritative motions, as hectic fevers, may again be 
produced by them, yet no fenfation, and in confequence no 
general inflammation fucceeds; as difagreeablc fmells or taftes 
by habit ceafe to be perceived ; they continue indeed to excite 
irritative ideas on the organs of fenfe, but thefe are not fucceed- 
ed by fenfation. 
There are many irritative motions, which were at firft fuc- 
ceeded by fenfation, but which by frequent repetition ceafe to ex- 
cite fenfation, as explained in Seft. XX. on Vertigo. And, that 
this circumflance exifts in refpeft to infectious matter appears 
from a known fact; that nurfes, who have had the fmall-pox, 
are liable to experience fmall ulcers on their arms by the contact 
of variolous matter in lifting their patients; and that when pa- 
tients, who have formerly had the fmall-pox have been inocula- 
ted in the arm, a phlegmon, or inflamed fore, has fucceeded, but 
no fubfequent fever. Which (hews, that the contagious matter 
of rhe fmall-pox has not loft its power of ftimulating the part it 
is applied to, but that the general fyflem is not affected in con- 
fequence. See Section XII. 7.6. XIX. 10. 
9. From the accounts of the plague, virulent catarrh, and 
putrid dyfentery, it feems uncertain, whether thefe difeafes are 
experienced more than once ; but the venereal difeafe and itch 
are doubtlefs repeatedly infeffious; and as thefe difeafes are 
never cured fpontaneoufly, but require medicines, which aft 
without apparent operation, fome have fufpecled, that the con- 
tagious material produces fimilar matter rather by a chemical 
change ofthe fluids,than by an animal procefs; and thatthe fpecif- 
ic medicines deftroy their virusby chemically combining withit. 
This opinion is fuecefsfully combated by Mr. Hunter, in his 
Treatife on Venereal Difeafe; Part I. c. i. 
But this opinion wants the fupport of analogy, as there is nt? 
known procefs in animal bodies, which is purely chemical, not 
evendigeflion ; nor can any of thefe matters be produced by 
chemical procefles. Add to this, that it is probable, that the 
infefts, obferved in the puftules of the itch, and in the ftoolsof 
dyfenteric patients, are the confequcnces, and not the caufes of 
thefe difeafes. And that the fpecific medicines, which cure the 
itch, and lues venerea, as brimflone and mercury, aft only by in- 
creafing Sect. XXXIII. 2. 9. 
OF SENSATION. 
313 
creafing the abforption of the matter in the ulcufcles of thofe 
difeafes, and thence difpofing them to heal ; which would other- 
wife continue to fpread. 
Why the venereal difeafe, and itch, and tinea, or fcald head, 
are repeatedly contagious, while thofe contagions attended with 
fever can be received but once, feems to depend on their being 
rather local difeafes than univerfal ones, and are hence not at- 
tended with fever, except the purulent fever in their laft flages, 
when the patient is deftroyed by them. On this account the 
whole of the fyftem does not become habituated to thefe morbid 
actions, fo as to ceafe to be affected with fenfation by a repetition 
of the contagion. Thus the contagious matter of the venereal 
difeafe, and of the tinea, affeCts the lymphatic glands, as the in- 
guinal glands, and thofe about the roots of the hair and neck, 
where it is arretted, but does not feem to affeCl the blood-veifels, 
fince no fever enfues. 
Hence it would appear, that thefe kinds of contagion are prop- 
agated not by means of the circulation, but by fympathy of dif- 
tant parts with each other ; fince if a diftant part, as the palate, 
fhould be excited by fenfitive aflbciation into the fame kind of 
motions, as the parts originally affected by the contact of infec- 
tious matter ; that dittant part will produce the fame kind of 
infectious matter ; for every fecretion from the blood is formed 
from it by the peculiar motions of the fine extremities of the 
gland, which fecretes it; the various fecreted fluids, as the bile, 
faliva, gaftric juice, not previoufly exitting, as fuch, in the blood- 
veflels. 
And this peculiar fympathy between the genitals and the 
throat, owing to fenfitive aflbciation, appears not only in the 
production of venereal ulcers in the throat, but in a variety of 
other inttances, as in the mumps, in the hydrophobia, fome coughs, 
ftrangulation, the production of the beard, change of voice at 
puberty, which are further defcribed in Oafs IV. r. 2. 7. 
To evince that the production of fuch large quantities of con- 
tagious matter, as are feen in fome variolous patients, fo as to 
cover the whole ikin almoft with puftules, does not arife from 
any chemical fermentation in the blood, but that it is owing to 
morbid motions of the fine extremities of the capillaries, or 
glands, whether thefe be ruptured or not, appears from the quan- 
tity of this matter always correfponding with the quantity of the 
fever ; that is, with the violent exertions of thofe glands and 
capillaries, which are the terminations of the arterial fyttem. 
The truth of this theory is evinced further by a circumttance 
obferved by Mr. J. Hunter, in his Treatife on Venereal Difeafe ; 
that in a patient, who was inoculated for the fmall-pox, and 
Vol. I. R r who 314 
DISEASES 
Sect. XXXIII. 2. 9- 
who appeared afterwards to have been previoufly infected with 
the meafles, the progrefs of the fmall-pox was delayed till the 
meafles had run their courfe, and that then the fmall-pox went 
through its ufual periods. 
Two fimilar cafes fell under my care, which I (hall here re- 
late, as it confirms that of Mr. Hunter, and contributes to illuf- 
trate this part of the theory of contagious difeafes. 1 have tranf- 
cribedthe particulars from a letter of Mr. Lightwood, of Yoxal, 
the furgeon who daily attended them, and at my requeft, after I 
had feen them, kept a kind of journal of their cafes. 
Mifs H. and Mifs L. two filters, the one about four and the 
other about three years old, were inoculated Feb. 7, 1791. On 
the 10th there was arednefs on both arms difcernible by a glafs. 
On the 11 th their arms were io much inflamed, as to leave no 
doubt of the infection having taken place. On the 12th lefs 
appearance of inflammation on their arms. In the evening Mifs 
L. had an eruption, which refembledthe meafles. On the 13 th 
the eruption on Mifs L. was very full on the face and breaft, 
like the meafles, with confiderable fever. It was now known, 
that the meafles were in a farm houfe in the neighbourhood. 
Mifs H.'s arm lefs inflamed than yefterday. On the 14th Mifs 
L.'s fever great, and the eruption univerfal. The arm appears 
to be healed. Mifs H.'s arm fomewhat redder. They were 
now put into feparate rooms. On the 15th Mifs L.'s arms as 
yefterday. Eruption continues. Mifs H.'s arms have varied 
but little. 16th, the eruptions on Mifs L. are dying away, her 
fever gone. Begins to have a little rednefs in one arm at the 
place of inoculation. Mifs H.'s arms get redder, but fhe has no 
appearance of complaint. 20th, Mifs L's arms have advanced 
flowly till this day, and now a few puftules appear. Mifs H.'s 
arm has made little progrefs from the 16th to this day, and now 
Ihe has fome fever. 21ft, Mifs L. as yefterday. Mifs H. has 
much inflammation, and an increafe of the red circle on one arm 
to the fize of half-a-crown, and had much fever at night, with 
fetid breath. 22d, Mifs L.'s puftules continue advancing. Mifs 
H.'s inflammation of her arm and red circle increafes. A few 
red fpots appear in different parts with fome degree of fever this 
morning. 23d, Mifs L. has a larger crop of puftules. Mifs 
H. has fmall puftules and great inflammation of her arms, with 
but one puftule likely to fuppurate. After this day they gradu- 
ally got well, and the puftules difappeared. 
In one of thefe cafes the meafles went through their common 
courfe with milder fymptoms than ufual, and in the other the 
meafly contagion feemed juft fufficicnt to ftop the progrefs of 
variolous contagion, but without itfelf throwing the conftitution 
z into Sect. XXXIII. 2. 10. 
OF SENSATION. 
315 
into any diforder. At the fame time both the mealies and fmall- 
pox feem to have been rendered milder. Does not this give an 
idea, that if they were both inoculated at the fame time, that 
neither of them might afleft the patient ? 
From thefe cafes I contend, that the contagious matter of 
thefe difeafes does not affeft the conftitution by a fermentation, 
or chemical change of the blood, becaufe then they mult have 
proceeded together, and have produced a third fomething, not 
exactly fimilar to either of them : but that they produce new 
motions of the cutaneous terminations of the blood-vefl'els, 
which for a time proceed daily with increasing activity, like 
fome paroxyfms of fever, till they at length fecrete or form a 
fimilar poifon by thefe unnatural actions. 
Now as in the mealies one kind of unnatural motion takes 
place, and in the fmall-pox another kind, it is eafy to conceive, 
that thefe different kinds of morbid motions cannot exift togeth- 
er ; and therefore, that that which has firft begun will continue 
till the fyftem becomes habituated to the ftimulus which occa- 
fions it, and has ceafed to be thrown into action by it; and then 
the other kind of ftimulus will in its turn produce fever, and 
new kinds of motions peculiar to itfelf. 
io. On further confidering the action of contagious matter, 
fince the former part of this work was fent to the prefs; where 
I have aflerted, in Se£t. XXII. 4. 3. that it is probable, that the 
variolous matter is diffufed through the blood ; I prevailed on 
my friend Mr. Power, furgeon at Bofworth, in Leicefterfhire, to 
try, whether the fmall-pox could be inoculated by ufing the blood 
of a variolous patient inftead of the matter from the puftules ; 
as I thought fuch an experiment might throw fome light at 
leaft on this interefting fubjeft. The following is an extract 
from his letter :- 
"March 11, 1793. I inoculated two children, who had not 
had the Imall-pox, with blood ; which was taken from a patient 
on the fecond day after the eruption commenced, and before it 
was completed. And at the fame time I inoculated myfelf with 
blood from the fame perfon, in order to compare the appearances, 
which might arife in a perfon liable to receive the infection, and 
in one not liable to receive it. On the fame day I inoculated 
four other children liable to receive the infection with blood 
taken from another perfon on the fourth day after the com- 
mencement of the eruption. The patients from whom the blood 
was taken had the difeafe mildly, but had the moft puftules of 
any I could feleQ from twenty inoculated patients ; and as 
much of the blood was infinuated under the cuticle, as I could 
introduce by elevating the Ikin without drawing blood ; and 
three 316 
DISEASES 
Sect. XXXIII. 2. 1*. 
three or four fuch puntlures were made in each of their arms, 
and the blood was ufed in its fluid ftate. 
" As the appearances in all thefe patients, as well as in myfelf, 
were fimilar, I fhall only mention them in general terms. 
March 13. A flight fubcuticular difcoloration, with rather a 
livid appearance, without forenefs or pain, was vifible in them 
all, as well as in my own hand. 15. The difcoloration fome- 
what lefs, without pain or forenefs. Some patients inoculated 
on the fame day with variolous matter have confiderable inflam- 
mation. 17. The difcoloration is quite gone in them all, and 
from my own hand, a dry mark only remaining. And they 
were all inoculated on the 1 8th, with variolous matter, which 
produced the difeafe in them all." 
Mr. Power afterwards obferves, that, as the patients from 
whom the blood was taken had the difeafe mildly, it may be 
fuppofed, that though the contagious matter might be mixed 
with the blood, it might ftill be in too dilute a ftate to convey 
the infection ; but adds at the fame time, that he has diluted 
recent matter with at leaft five times its quantity of water, and 
which has ftill given the infeilion ; though he has fometimes 
diluted it fo far as to fail. 
The following experiments were inftituted at my requeft by 
my friend Mr. Hadley, furgeon in Derby, to afcertain whether 
the blood of a perfon in the fmall-pox be capable of communi- 
cating the difeafe. " Experiment 1 ft. October 1 §th, 1793. I 
took fome blood from a vein in the arm of a perfon who had 
the fmall-pox, on the fecond day of the eruption, and introdu- 
ced a fmall quantity of it immediately with the point of a lancet 
between the fcarf and true fkin of the right arm of a boy nine 
years old in two or three different places ; the other arm was 
inoculated with variolous matter at the fame time. 
" 19th. The pumTured parts of the right arm were furround- 
ed with fome degree of fubcuticular inflammation. 20th. 'Die 
inflammation more confiderable, with a flight degree of itching, 
but no pain upon prellure. 21ft. Upon examining the arm 
this day with a lens, I found the inflammation lets extenfive, 
and the rednefs changing to a deep yellow or orange-colour. 
22d. Inflammation nearly gone. 23d. Nothing remained, except 
a flight difcoloration and a little feurfy appearance on the punc- 
tures. At the fame time the inflammation of the arm inoculated 
with variolous matter was increafing faft, and he had the difeafe 
mildly at the ufual time. 
" Experiment 2d. 1 inoculated another child at the fame 
time and in the fame manner, with blood taken on the firft day 
pf the eruption ; but as the appearance and effects were fimilar 
to Sect. XXXIII. 2. 10. 
OF SENSATION. 
317 
to thofe in the preceding experiment, I Ihall not relate them 
minutely. 
" Experiment 3d. Odlober 20th. Blood was taken from a 
perlon who had the fmall-pox, on the third day of the eruption, 
and on the fixth from the commencement of the eruptive fever. 
I introduced fome of it in its fluid Hate into both arms of a boy 
feven years old. 21. There appeared to be fome inflammation 
under the cuticle, where the pundlures were made. 22d. In- 
flammation more confiderable. 23d. On this day the inflamma- 
tion was fomewhat greater, and the cuticle rather elevated. 
24th. Inflammation much lefs, and only a brown or orange- 
colour remained. 25th. Scarcely any difcoloration left. On 
this day he was inoculated with variolous matter, the progrefs of 
rhe infection went on in the ufual way, and he had the fmall- 
pox very favourably. 
" At this time I was requefted to inoculate a young perfon, 
who was thought to have had the fmall-pox, but his parents were 
not quite certain ; in one arm I introduced variolous matter, and 
in the other blood, taken as in experiment 3d. On the fecond 
day after the operation, the pundtured parts were inflamed, 
though I think the arm in which I had inferred variolous mat- 
ter was rather more fo than the other. On the third the inflam- 
mation was increafed, and looked much the fame as in the pre- 
ceding experiment. 4th. The inflammation was much dimin- 
ilhed, and on the 5th almoft gone. He was expoi'ed at the fame 
time to the natural infedtion, but has continued perfectly well. 
" I have frequently obferved (and believe molt practitioners 
have done the fame), that if variolous matter be inferted in the 
arm of a perfon who has previously had the fmall-pox, the in- 
flammation on the fecond or third day is much greater, than if 
they had not had the difeafe, but on the fourth or fifth it dif- 
appears. 
" On the 23d I introduced blood into the arms of three more 
children, taken on the third and fourth days of the eruption. 
The appearances were much the fame as mentioned in experi- 
ments firft and third. They were afterwards inoculated with 
variolous matter, and had the difeafe in the regular way. 
" The above experiments were made with blood taken from a 
fmall vein in the hand or foot of three or four different patients, 
whom I had at that time under inoculation. They were feledt- 
ed from 160, as having the greateft number of puftules. The 
part was walhed with warm water before the blood was taken, 
to prevent the polhbility of any matter being mixed with it from 
the lurface." 
Shall we conclude from hence, that the variolous matter never 
eaters 318 
DISEASES 
Sect. XXXIII. 2. io. 
enters the blood-veflels; but that the morbid motions of the vef- 
fels of the fkin around the infertion of it continue to increafe in 
a larger and larger circle for fix or feven days; that then their 
quantity of morbid atftion becomes great enough to produce a 
fever-fit, and to affeCt the ftomach by aflbciation of motions ? 
and finally, that a fecond aflbciation of motions is produced be- 
tween the ftomach and the other parts of the fkin, inducing 
them into morbid actions fimilar to thofe of the circle round 
the infertion of the variolous matter ? Many more experiments 
and obfervations are required before this important queftion can 
be fatisfactorily anfwered. 
It may be adduced, that as the matter inferted into the fkin of 
the arm frequently fwells the lymphatic in the axilla, that in that 
circumftance it feems to be there arrefted in its progrefs, and 
cannot be imagined to enter the blood by that lymphatic gland 
till the fwelling of it fubfides. Some other phenomena of the 
difeafe are more eafily reconcileable to this theory of fympathet- 
ic motions than to that of abforption ; as the time taken up be- 
tween the infertion of the matter, and the operation of it on the 
fyftem, as mentioned above. For the circle around the infertion 
is feen to increafe, and to inflame; and I believe, undergoes a 
kind of diurnal paroxyfm of torpor and palenefs with a fucceed- 
ing increafe of aCtion and colour, like a topical fever-fit. 
Whereas if the matter is conceived to circulate for fix or feven 
days with the blood, without producing diforder, it ought to be 
rendered milder, or the blood-veflels more familiarized to its 
acrimony. 
It is much eafier to conceive from this doctrine of aflbciated 
or fympathetic motions of diftant parts of the fyftem, how it 
happens, that the variolous infection can be received but once, 
as before explained ; than by fuppofing, that a change is effect- 
ed in the mafs of blood by'any kind of fermentative procefs. 
The curious circumftance of the two contagions of fmall-pox 
and meafles not aCting at the fame time, but one of them refting 
or fufpending its aCtion till that of the other ceafes, may be much 
eafier explained from fympathetic or aflbciated aCtions of the in- 
fected part with other parts of the fyftem, than it can from fup- 
pofing the two contagions to enter the circulation. 
The fkin of the face is fubjeCt to more frequent viciflitudes of 
heat and cold, from its expofure to the open air, and is in con- 
fequence more liable to fenfitive aflbciation with the ftomach 
than any other part of the furface of the body, becaufe their ac- 
tions have been more frequently thus aflbciated. Thus in a 
furfeit from drinking cold water, when a perfon is very hot and 
fatigued, an eruption is liable to appear on the face in confe- 
quence Sect. XXXIII. 3. 1. 
OF SENSATION. 
319 
quence of this fympathy. In the fame manner the rofy eruption 
on the faces of drunkards more probably arifes from the fympathy 
of the face with the ftomach, rather than between the face and 
the liver, as is generally fuppofed. 
This fympathy between the ftomach and the Ikin of the face is 
apparent in the eruption of the fmall-pox ; fince, where the dif- 
eafe is in conliderable quantity, the eruption on the face firft 
fucceeds the ficknefs of the ftomach. In the natural difeafe the 
ftomach feems to be frequently primarily affected, either alone 
or along with the tonfils, as the matter feems to be only diffufed 
in the air, and by being mixed with the faliva, or mucus of the 
tonfils, to be fwallowed into the ftomach. 
After fome days the irritative circles of motions become dif- 
ordered by this new ftimulus, which afts upon the mucous li- 
ning of the ftomach; and ficknefs, vertigo, and diurnal fever 
fucceed. Thefe difordered irritative motions become daily in- 
creafed for two or three days, and then by their increafed action 
certain fenfitive motions, or inflammation, is produced, and at 
the next cold fit of fever, when the ftomach recovers from its 
torpor, an inflammation of the external flein is formed in points 
(which afterwards fuppurate), by fenfitive aflbeiation, in the 
fame manner as a cough is produced in confequence of expofing 
the feet to cold, asdefcribed in Sect. XXV. i. I. and Clafs IV. 
2. 1.7. If the inoculated fkin of the arm, as far as it appears 
inflamed, was to be cut out, or deftroyed by cauftic, before the 
fever commenced, as fuppofe on the fourth day after inoculation, 
would this prevent the difeafe ? as it is fuppofed to prevent the 
hydrophobia. 
III. 1. Where the new veflels, and enlarged old ones, which 
conftitute inflammation, are not fo haftily diftended as to burft. 
and form a new kind of gland for the fecretion of matter, as 
above mentioned ; if fuch circumftances happen as diminifh the 
painful fenfation, the tendency to growth ceafes, and by and by 
an abforption commences, not only of the fuperabundant quan- 
tity of fluids depofited in the inflamed part, but of the folids 
likewife, and this even of the hardeft kind. 
Thus during the growth of the fecond fet of teeth in children, 
the roots of the firft fet are totally abforbed, till at length noth- 
ing of them remains but the crown ; though a few weeks before, 
if they are drawn immaturely, their roots are found complete. 
Similar to this Mr. Hunter has obferved, that where a dead 
piece of bone is to exfoliate, or to feparate from a living one, 
the dead part does not putrefy, but remains perfeftly found, 
while the furface of the living part of the bone, which is in con- 
tact with the dead part, becomes abforbed, and thus eflefts its 
feparation. 320 
DISEASES 
Sect. XXXIII. 3. 2. 
reparation. Med. Comment. Edinb. V. i. 425. In the fame 
manner the calcareous matter of gouty concretions, the coagula- 
ble lymph depofited on inflamed membranes in rheumatifm and 
extravafated blood become abforbed; which are all as folid and as 
indiflbluble materials as the new veflels produced in inflammation. 
This abforption of the new veflels and depofited fluids of in- 
flamed parts is called refolution : it is produced by firfl: ufing 
fuch internal means as decreafe the pain of the part, and in con- 
fequence Its new motions, as repeated bleeding, cathartics, dilu- 
ent potations, and warm bath. 
After the veflels are thus emptied, and the abforption of the 
new veflels and depofited fluids is evidently begun, it is much 
promoted by ftimulating the part externally by folutions of lead, 
or other metals, and internally by the bark, and fmall dofes of 
opium. Hence when an ophthalmy begins to become paler, 
any acrid eye water, as a folution of fix grains of white vitriol 
in an ounce of water, haftens the abforption, and clears the eye 
in a very fhort time. But the fame application ufed a few days 
fooncr would have increafed the inflammation. Hence after 
evacuation opium in fmall dofes may contribute to promote the 
abforption of fluids depofited on the brain, as obferved by Mr. 
Bromfield in his treatife of furgery. 
2. Where an abfeefs is formed by the rupture of thefe new* 
veflels, the violence of inflammation ceafes, and a new gland 
feparates a material called pus : at the fame time a lefs degree 
of inflammation produces new veflels called vulgarly proud 
flefh; which, if no bandage confines its growth, nor any other 
circumftance promotes abforption in the wound, would rife to a 
great height above the ufual fizc of the part. 
Hence the art of healing ulcers conlilts in producing a ten- 
dency to abforption in the wound greater than the depofition. 
Thus when an ill-conditioned ulcer feparates a copious and thin 
difeharge, by the ufe of any ftimulus, as of faits of lead, or mer- 
cury, or copper externally applied, the difeharge becomes dimin- 
ifhed in quantity, and becomes thicker, as the thinner parts are 
firfl: abforbed. 
To which in ulcerations of the lungs, and in fome catarrhs, a 
pertinacious abftinence from fluids has been recommended, as 
well as in dropfies, and diabetes, which in the former as well as 
in the latter, may have a tendency to increafe abforption from 
the affetled parts, and may thus be moderately employed with 
advantage ; but may have a dangerous tendency if ufed to an 
extreme, by inducing too great third:, and confequent fever or 
inflammation. Lower de Catarrhis. Davidfon on Pulmonary 
Syllem. Rollo on Diabetes. 
But Sect. XX^III. 3. 3. 
OF SENSATION. 
321 
But nothing fo much contributes to increafc the abforption in 
a wound as covering the whole limb above the fore with a band- 
age, which fhould be fpread with fome plafter, as with emplaf- 
trum de minio, to prevent it from flipping. By this artificial 
tightnefs of the ikin, the arterial pulfations aft with double their 
ufual power in promoting the afeending current of the fluid in 
the valvular lymphatics. 
Internally the abforption from ulcers fhould be promoted firft 
by evacuation, then by opium, bark, mercury, fteel. 
3. Where the inflammation proceeds with greater violence 
or rapidity, that is, when by the painful fenfation a more inordi- 
nate aftivity of the organ is produced, and by this great aftivity 
an additional quantity of painful fenfation follows in an increafing 
ratio, till the whole of the fcnforial power, or fpirit of animation, 
in the part becomes exhaufted, a mortification enfues, as in a 
carbuncle, in inflammations of the bowels, in the extremities of 
old people, or in the limbs of thofe who are brought near a 
fire after having been much benumbed with cold. And from 
hence it appears, why weak people are more fubjeft to mortifi- 
cation than ftrong ones, and why in weak perfons lefs pain will 
produce mortification, namely, becaufe the fenforial power is 
fooner exhaufted by any excels of aftivity. I remember feeing 
a gentleman who had the preceding day travelled two ftages in 
a chaife with what he termed a bearable pain in his bowels ; 
which when I faw him had ceafed rather Suddenly, and without 
2 paflage through him •, his pulfe was then weak, though not 
very quick ; but as nothing which he fwallowed would continue 
in his ftomach many minutes, I concluded that the bowel was 
mortified ; he died on the next day. It is ufual for patients 
finking under the fmall-pox with mortified puftules, and with 
purple fpots intermixed, to complain of no pain, but to fay they 
•are pretty well to the laft moment. 
Recapitulation. 
IV. When the motions of any part of the fyftem, in confe- 
quence of previous torpor, are performed with more energy 
than in the irritative fevers, a difagreeable fenfation is produced, 
and new aft ions of fome part of the fyftem commence in con- 
fequence of this fenfation conjointly with the irritation : which 
motions conftitute inflammation. If the fever be attended with 
a ftrong pulfe, as in pleurify, or rheumatifm, it is termed fyno- 
cha fenfitiva or fenfitive fever with ftrong pulfe ; which is ufu- 
ally termed inflammatory fever. If it be attended with weak 
Vol. I. S s pulfe. 322 
DISEASES 
Sect. XXXIII. 4. 1. 
pulfe, it is termed typhus fenfitivus, or fenfitive fever with weak 
pulfe, or typhus gravior, or putrid malignant fever. 
The fynocha fenfitiva, or fenfitive fever with ftrong pulfe, is 
generally attended with fome topical inflammation, as in perip- 
neumony, hepatitis, and is accompanied with much coagulable 
lymph, or fize; which rifes to the furface of the blood, when 
taken into a bafin, as it cools; and which is believed to be the 
increafed mucous fecretion from the coats of the arteries, infpif- 
fated by a greater abforption of its aqueous and faline part, and 
perhaps changed by its delay in the circulation. 
The typhus fenfitivus, or fenfitive fever with weak pulfe, is 
frequently attended with delirium, which is caufed by the de- 
ficiency of the quantity of fenforial power, and with variety of 
cutaneous eruptions. 
Inflammation is caufed by the pains occafioned by excefs of 
action, and not by thofe pains which are occafioned by defeat of 
action. Thefe morbid actions, which are thus produced by two 
fenforial powers, viz. by irritation and fenfation, fecrete new 
living fibres, which elongate the old veflels, or form new ones, 
and at the fame time much heat is evolved from thefe combina- 
tions. By the rupture of thefe veflels, or by a new conftruction 
of their apertures, purulent matters are fecreted of various kinds ; 
which are infectious the firft time they are applied to the (kin 
beneath the cuticle, or fwallowed with the faliva into the ftom- 
ach. This contagion acts not by its being abforbed into the 
circulation, but by the fympathies, or aflbeiated actions, between 
the part firft ftimulated by the contagious matter and the other 
parts of the fyftem. Thus in the natural fmall-pox the conta- 
gion is fwallowed with the faliva, and by its ftimulus inflames the 
ftomach ; this variolous inflammation of the ftomach increafes 
every day, like the circle round the puncture of an inoculated 
arm, till it becomes great enough to diforder the circles of irrita- 
tive and fenfitive motions, and thus produces fever-fits, with 
ficknefs and vomiting. Laftly, after the cold paroxyfm, or fit 
of torpor, of the ftomach has increafed for two or three fuccef- 
five days, an inflammation of the fkin commences in points ; 
which generally firft appear upon the face, as the aflbeiated ac- 
tions between the fkin of the face and that of the ftomach have 
been more frequently exerted together than thofe of any other 
parts of the external furface. 
Contagious matters, as thofe of the meafles and fmall-pox, do 
not aft upon the fyftem at the fame time ; but the progrefs of 
that which was laft received is delayed, till the aclion of the for- 
mer infection ceafes. All kinds of matter, even that from com- 
mon ulcers, are probably contagious the firft time they arc in- 
ferted Sect. XXXIII. 4- i- 
OF SENSATION. 
323 
ferted beneath the cuticle or fwallowed into the ftomach; that 
is, as they were formed by certain morbid a&ions of the ex- 
tremities of the veflels, they have the power to excite fimilar 
morbid actions in the extremities of other veflels, to which they 
are applied ; and thefe by fympathy, or aflbciations of motion, 
excite fimilar morbid actions in diftant parts of the fyftem, with- 
out entering the circulation ; and hence the blood of a patient 
in the fmall-pox will not give that difeafe by inoculation to others. 
When the new fibres or veflels become again abforbed into 
the circulation, the inflammation ceafes; which is promoted, 
after fufficient evacuations, by external ftimulants and bandages : 
but where the action of the veflels is very great, a mortification 
of the part is liable to enfue, owing to the exhauftion of fenfori- 
al power; which however occurs in weak people without much 
pain, and without very violent previous inflammation ; and, like 
partial paralyfis, may be efteemed one mode of natural death 
of old people, a part dying before the whole. 
SECT. 324 
DISEASES 
Sect. XXXIV. i. 
SECT. XXXIV. 
DISEASES OF VOLITION. 
I. I. Volition defined. Motions termed involuntary are caufed by 
volition. Defires oppofed to each other. Deliberation. Afs be- 
tween two hay-cocks. Saliva /wallowed againft one's defitre. 
Voluntary motions dijlinguifhed from thofe ajfociated with fenfitive 
motions. 2. Pains from excefs, and from defect of motion. No 
pain is felt during vehement voluntary exertion ; as in cold fits of 
ague, labour-pains, firangury, tenefmus, vomiting, rejllefinefs in 
fevers, convulfion of a wounded tnufcle. 3. Of holding the breath 
andfireaming in pain ; why fwine and dogs cry out in pain, and 
not jheep and horfes. Of grinning and biting in pain ; why mad 
animals bite others. 4. Epileptic convulfions explained, why the 
fits begin with quivering of the under jaw, biting the tongue, and 
fitting the teeth ; why the convulfive motions are alternately relax- 
ed. Thephenomenon of laughter explained. Why children can- 
not tickle themfelves. How fame have died from immoderate 
laughter, g. Of cataleptic fpafms, of the locked jaw, of painful 
cramps. 6. Syncope explained. Why no external objects are 
perceived in fyncope. q. Of palfy and apoplexy from violent exer- 
tions. Cafe of Mrs. Scot. From dancing, /eating, fwimming. 
Cafe of Mr. Nairne. Why palfies are not always immediately 
preceded by violent exertions. Pal/y and epilep/y from difeafed 
livers. Why the right arm more frequently paralytic than the 
left. How paralytic limbs regain their motions. IL Difia/es of 
the finfual motions from excefs or defect of voluntary exertion. 
1. Madnefi. 2. Dijlinguifhed from delirium 3. Why man- 
kind more liable to infinity than brutes. Sufpicion. Want of 
jhame, and of cleanUnefs. 5. They bear cold, hunger, and fatigue. 
Charles XII. of Sweden. 6. Pleafurable delirium, and infinity. 
Child riding on a flick. Pains of martyrdom not felt. q. Drop- 
fy. 8. Inflammation cured by infinity. III. I. Pain relieved 
by reverie. Reverie is an exertion of voluntary and fenfitive mo- 
tions. 2. Cafe of reverie. 3. Lady fuppofed to have two fouls. 
4. Methods of relieving pain. 
I. i. Before we commence this Section on Difeafed Vol- 
untary Motions, it may be neceflary to premife, that the word 
volition is not ufed in this work exactly in its common accepta- 
tion. Volition is faid in Seilion V. to bear the fame analogy to 
defire and averfion, which fenfation does to pleafure and pain. 
And hence that, when dcfire or averfion produces any aition of 
the .Sect. XXXIV. i. i. 
OF VOLITION. 
325 
the mufcular fibres, or of the organs of fenfe, it is termed voli- 
tion ; and the actions produced in confequence are termed vol- 
untary actions. Whence it appears, that motions of our muf- 
cles or ideas may be produced in confequence of defire or aver- 
fion without our having the power to prevent them, and yet thelc 
motions may be termed voluntary, according to our definition of 
the word ; though in common language they would be called 
involuntary. 
The objects of defire and averfion are generally at a diftance, 
whereas thofe cf pleafure and pain are immediately acting upon 
our organs. Hence, before defire or averfion is exerted, fo as 
to caufe any actions, there is generally time for deliberation ; 
which confifts in difeovering the means to obtain the objeCl ot 
defire, or to avoid the object of averfion ; or in examining the 
good or bad confequences, which may refult from them. In 
this cafe it is evident, that we have a power to delay the pro- 
pofed aflion, or to peiformitj and this power of chooling, 
whether we (hail aft or not, is in common language exp; tiled 
by the word volition, or will. Whereas in this work the word 
volition means fimply the aflive ftate of the fenforial faculty ra 
producing motion in confequence of defire or averfion ; whether 
we have the power of retraining that action, or not; that is, 
whether we exert any actions in confequence of opposite de tires 
or averfions or not. 
For if the objects of defire or averfion are prefent, there is no 
necefhty to inveftigate or compare the means of obtaining them., 
nor do we always deliberate about their confequences ; that is, 
no deliberation neceffarily intervenes, and in ccnfequence the 
power of choofing to aft or not is not exerted. It is probable, 
that this two-fold ufe of the word volition in all languages ha« 
confounded the metaphyficians, who have difputed about free 
will and neceffity. Whereas from the above analyfis it would 
appear, that during our fleep, we ufe no voluntary exertions at. 
all ; and in our waking hours, that they are the confequence of 
.defire or averfion. 
To will is to aft in confequence of defire ; but to defire 
means to defire fomething, even if that fomething be only to be- 
come free from the pain, which caufes the defire ; for to defire 
nothing is not to defire ; the word defire, therefore, includes 
both the aflion and the objeft or motive; for the objeft and 
motive of defire are the fame thing. Hence to defire without an 
objeft, that is, without a motive, is a folecifm in language. As 
if one fhould alk, if you could eat without food, or breathe 
'without air. 
From this account of volition it appears, that convulfions of 
the 326 
DISEASES 
Sect. XXXIV. 1. 1. 
the mufcles, as in epileptic fits, may in the common fenfe of that 
word be termed involuntary; becaufe no deliberation is interpo- 
fed between the defire or averfion and the confequent aflion ; 
but in the fenfe of the word, as above defined, they belong to the 
clafs of voluntary motions, as delivered in Vol. I. Clafs III. 
If this ufe of the word be difcordant to the ear of the reader, 
the term morbid voluntary motions, or motions in confequence 
of averfion, may be fubftituted in its ftead. 
If a perfon has a defire to be cured of the ague, and has at the 
fame time an averfion (or contrary defire) to fwallowing an ounce 
of Peruvian bark; he balances defire againft defire, or averfion 
againft averfion ; and thus he acquires the power of choofing, 
which is the common acceptation of the word 'tuiUing. But in 
the cpld fit of ague, after having difcovered that the act of 
(huddering, or exerting the fubcutaneous mufcles, relieves the 
pain of cold ; he immediately exerts this aft of volition, and 
ihudders, asfoon as the pain and confequent averfion return, 
without any deliberation intervening ; yet is this aft, as well as 
that of fwallowing an ounce of the bark, caufed by volition ; and 
that even though he endeavours in vain to prevent it by a weak- 
er contrary volition. This recalls to our minds the flory of the 
hungry afs between two hay-ftacks, where the two defires are 
fuppofed fo exaflly to counterafl each other, that he goes to 
neither of the flacks, but perifhes by want. Now as two equal 
and oppofite defires are thus fuppofed to balance each other, 
and prevent all aflion, it follows, that if one of thefe hay-flacks 
was fuddenly removed, the afs would irrefiflibly be hurried to 
the other, which in the common ufe of the word might be call- 
ed an involuntary afl ; but which, in our acceptation of it, 
would be claffed amongfl voluntary aftions, as above explained. 
Hence to deliberate is to compare oppofing defires or aver- 
fions, and that which is the moil interefting at length prevails, 
and produces aflion. Similar to this, where two pains oppofe 
each other, the flronger or more interefting one produces ac- 
tion ; as in pleurify the pain from fuffocation would produce 
expanfion of the lungs, but the pain occafioned by extending 
the inflamed membrane, which lines the cheft, oppofes this ex- 
panfion, and one or the other alternately prevails. 
When any one moves his hand quickly near another perfon's 
eyes, the eye-lids inftantly clofe ; this afl in common language 
is termed involuntary, as we have not time to deliberate or to 
exert any contrary defire or averfion, but in this work it would 
be termed a voluntary afl, becaufe it is caufed by the faculty of 
volition, and after a few trials the niflitation can be prevented 
by a contrary or oppofing volition. 
The Sect. XXXIV. 1. 1. 
OF VOLITION. 
327 
The power of oppofing volitions is beft exemplified in the 
ftory of Mutius Scsevola, who is faid to have thruft his hand 
into the fire before Porcenna, and to have fuffered it to be con- 
fumed for having failed him in his attempt on the life of that 
general. Here the averfion for the lofs of fame, or the unfatis- 
fied defire to ferve his country, the too prevalent enthufiafms at 
that time, were more powerful than the defire of withdrawing 
his hand, which muft be occafioned by the pain of combuftion 5 
of thefe oppofing volitions 
Vincit amor patriae, laudumque immenfa cupido. 
If any one is told not to fwallow his faliva for a minute, he 
foon fwallows it contrary to his will, in the common fenl'e of that 
word ; but this alfo is a voluntary action, as it is performed by 
the faculty of volition, and is thus to be underftood. When 
the power of volition is exerted on any of our fenfes, they be- 
come more acute, as in our attempts to hear fmall noifes in the 
night. As explained in Setflion XIX. 6. Hence by our atten- 
tion to the fauces from our dcfire not to fwallow our faliva ; 
the fauces become more fenfible ; and the flimulus of the fali- 
va is followed by greater fenfation, and confequent de fire of 
fwallowing it. So that the defire or volition in confequence of 
the increased fen Cation of the faliva is more powerful, than the 
previous defire not to fwallow it. See Vol. I. Deglutitio in- 
vita. In the fame manner if a modeft man willies not to want 
to make water, when he is confined with ladies in a coach or art 
affembly-room ; that very act of volition induces the circum- 
ftance, which he wifhes to avoid, as above explained j infomuch 
that I once faw a partial infanity, which might be called a vol- 
untary diabetes, which was occafioned by the fear (and confe- 
quent averfion) of not being able to make water at all. 
It is further neceflary to obferve here, to prevent any confu- 
fion of voluntary, with fenfitive, or aflbeiate motions, that in ail 
the inftances of violent efforts to relieve pain, thole efforts are 
at firft voluntary exertions ; but after they have been frequent- 
ly repeated for the purpofe of relieving certain pains, they be- 
come affociated with thofe pains, and cqafe at thofe times to be 
fubfervient to the will ; as in coughing, freezing, and flrangu- 
ry. Of thefe motions thofe which contribute to remove or dif- 
lodge the offending caufe, as the actions of the abdominal muf- 
cles in parturition or in vomiting, though they were originally 
excited by volition, are in this work termed fenfitive motions ; 
but thofe actions of the mufcles or organs of fenfe, which do 
not contribute to remove the offending caufe, as in general con- 
vulfions or in madnefs, are in this work termed voluntary mo- 
tions. 328 
DISEASES 
Sect. XXXIV. i. 2. 
tions, or motions in confequence of averfion, though in common 
language they arc called involuntary ones. Thofe fenfitive un- 
reftrainable actions, which contribute to remove the caufe of 
pain are uniformly and invariably exerted, as in coughing or 
fneezing ; but thofe motions which are exerted in confequence 
of averfion without contributing to remove the painful caufe,but 
only to prevent the fenfation of it, as in epileptic or cataleptic 
fits, arc not uniformly and invariably exerted, but change from 
one fet of mufcles to another, as will be further explained : 
and may by this criterion alfo be diftinguiflied from the former. 
At the fame time thofe motions, which are excited by per- 
petual ftimulus, or by affociation with each other, or immedi- 
ately by p'eafurable or painful fenfation, may properly be term- 
ed involuntary motions, as thofe of the heart and arteries : as 
the faculty of volition feldom affefts thofe, except when it exifts 
in unnatural quantity, as in maniacal people. 
2. It was obferved in Section XIV. on the Production of 
Ideas, that thop parts of the fyltem, which are ufually termed 
the organs of fenfe, are liable to be excited into pain by the ex- 
cels of the ftimulus of thofe objects, which are by nature adap- 
ted to affect them ; as of too great light, found, or preffure. But 
that thefe organs receive no pain from the defect or abfence of 
thefe ftimuli, as in darknefs or filence. But that our other or- 
gans of perception, which have generally been called appetites, 
as of hunger, third, want of heat, want of frefh air, are liable to 
be affefted with pain by the defeat, as well as by the excefs of 
their appropriated ftimuli. 
This excefs or defect of ftimulus is however to beconfidered 
only as the remote caufe of the pain, the immediate caufe being 
the excefs or defect of the natural adion of the affeeffed part, 
accordmg toSeft. IV. 5. Hence all the pains of the body may 
be divided into thofe from excefs of motion, and thofe from de- 
fect of motion, which diftinflion is of great importance in the 
knowledge and the cure of many difeafes. For as the pains 
from the excefs of motion either gradually fubfide, or are in 
general fucceeded by inflammation ; fo thofe from defed of 
motion either gradually fubfide, or are in general fucceeded by 
convulsion, or madnefs. Thefe pains are eafily diftinguifhable 
from each other by this circumftance, that the former are attend- 
ed wuth heat of the pained part, or of the whole body ; where- 
as the latter exift without mcreafe of heat in the pained part, 
and are generally attended with coldnefs of the extremities of 
the body ; which is the true criterion of what have been called 
nervous pains. 
Thus when any acrid material, a< fnuff or lime, falls into the 
eye. Sect. XXXIV. 1. 2. 
OF VOLITION. 
329 
eye, pain and inflammation and heat are produced from the ex- 
cefs of ftimulus ; but violent hunger, hemicrania, or the clavas 
hyftericus, are attended with coldnefs of the extremities, and de- 
feat of circulation. When we are expofed to great cold, the 
pain we experience from the deficiency of heat is attended With 
a quiefcence of the motions of the vafcular fyltem ; fo that no 
inflammation is produced, but a great defire of heat, and a.trem- 
ulous motion of the fubcutaneous mufcles, which is properly a 
convulfion in confequence of this pain from defect of the ftimu- 
lus of heat. 
It was before mentioned, that as fenfation confifts in certain 
movements of the fenforhim, beginning at fome ol the extremi- 
ties of it, and propagated to the central parts of it ; fo volition 
confifts of certain other movements of the fenforium, commenc- 
ing in the central parts of it, and propagated to fome of itsextremi- 
ties. This idea of thefe two great powers of motion in the ani- 
mal machine is confirmed from observing, that they never exift 
in a great degree or univerfally at the fame time ; for while we 
ftrongly exert our voluntary motions, we ceafe to feel the pains 
or uneafinefles, which occalioned us to exert them. 
Hence during the time of fighting with lifts or fwords no 
pain is felt by the combatants, till they ceafe to exert themfelves. 
Thus in the beginning of ague-fits the painful fenfation of cold 
is diminilhed, while the patient exerts himfelf in the fhivering 
and gnafhing of his teeth. He then ceafes to exert himfelf, and 
the pain of cold returns ; and he is thus perpetually induced 
to reiterate thefe exertions, from which he experiences a tempo- 
rary relief. The fame occurs in labour-pains, the exertion of 
the parturient woman relieves the violence of the pains for a 
time, which recur again foon after ihe has ceafed to ufe thofe 
exertions. The fame is true in many other painful difeafes, as 
in the ftrangury, tenefmus, and the efforts of vomiting ; all 
thefe difagreeable fenfations are diminilhed or removed for a 
time by the various exertions they occafion, and recur alternately 
with thofe exertions. 
The reftleflhefs in fome fevers is an almoft perpetual exertion 
of this kind, excited to relieve fome difagreeable fenfations j the 
reciprocal oppofite exertions of a wounded worm, the alternate 
emprofthotonos and opifthotonos of fome fpafmodic difeafes, and 
the intervals of all convulfions, from whatever caufe, feem to be 
owing to this circumftance of the laws of animation ; that great 
or univerfal exertion cannot exift at the fame time with great 
or univerfal fenfation, though they can exift reciprocally ; which 
is probably refolvable into the more gdher.il law, that the whole 
fenforial power being expended in one mode of exertion, there 
Vol. I. T t is 330 
DISEASES 
Sect. XXXIV. i. 3. 
is none to fpare for any other. Whence fyncope, or temporary 
apoplexy, fucceeds to epileptic convulfions. 
3. Hence when any violent pain afflicts us, of which we cart 
neither avoid nor remove the caufe, we foon learn to endeavour 
to alleviate it, by exerting fome violent voluntary effort, as men. 
tioijed above ; and are naturally induced to ufe thofe mufcles 
for this purpofe, which have been in the early periods of our 
lives moft frequently or moft powerfully exerted. 
Now the firft mufcles, which infants ufe moft frequently, are 
thofe of refpiration ; and on this account we gain a habit of 
holding our breath, at the fame time that we ufe great efforts 
to exclude it, for this purpofe of alleviating unavoidable pain; 
or we prefs out our breath through a fmall aperture of the 
larynx, and fcream violently, when the pain is greater than is 
relievable by the former mode of exertion. Thus children 
fcream to relieve any pain either of body or mind, as from 
anger, or fear of being beaten. 
Hence it is'curious to obferve, that thofe animals, who have 
more frequently exerted their mufcles of refpiration violently, 
as in talking, barking, or grunting, as children, dogs, hogs, fcream 
much more, when they are in pain, than thofe other animals, 
who ufe little or no language in their common modes of life j 
as horfes, fheep, and cows. 
The next moft frequent or moft powerful efforts, which in- 
fants are firft tempted to produce, are thofe with the mufcles in 
biting hard fubftances ; indeed the exertion of thefe mufcles is 
very powerful in common maftication, as appears from the pain 
we receive, if a bit of bone is unexpectedly found amongft our 
fofter food ; and further appears from their aCiling to fo great 
mechanical difadvantage, particularly when we bite with the in- 
ciforcs, or canine teeth ; which are firft formed, and thence are 
firft ufcd to violent exertion. 
Hence when a perlon is in great pain, the caufe of which he 
cannot remove, he fets his teeth firmly together, or bites fome 
fubftance between them with great vehemence, as another 
mode of violent exertion to produce a temporary relief. Thus 
we have a proverb where no help can be had in pain, " to grin 
and abide and the tortures of hell are faid to be attended with 
(i gnafhingof teeth." 
Hence in violent fpafmodic pains I have feen people bite not 
only their tongues, but their arms or fingers, or thofe of the at- 
tendants, or any object which was near them ; and alfo ftrike, 
pinch, or tear, others or themfelves, particularly the part of 
their own body, which is painful at the time. Soldiers, who 
die of painful wounds in battle, are faid in Homer to bite the 
ground. Sect. XXXIV. 1.4. 
OF VOLITION. 
331 
ground. Thus alfo in the bellon, or colica faturnina, the pa- 
tients are faid to bite their own flelli, and dogs in this difeafe to 
bite up the ground they lie upon. It is probable that the great 
endeavours to bite in mad dogs, and the violence of other mad 
animals, are owing to the fame caufe. 
4. If the efforts of our voluntary motions are exerted with 
ftill greater energy for the relief of fome difagreeable fenfation, 
convulfions are produced ; as the various kinds of epilepfy, and 
in fome hyfteric paroxyfms. In all thefe difeafes a pain or difa- 
greeable fenfation is produced, frequently by worms,' or acidity 
in the bowels, or by a difeafed nerve in the fide, or head, or by 
the pain of a difeafed liver. 
In fome conftitutions a more intolerable degree of pain is 
produced in fome part at a diftance from the caufe bv fenfitive 
affociation, as before explained ; thefe pains in fuch conftitutions 
arife to fo great a degree, that I verily believe no artificial tor- 
tures could equal fome, which I have witneffed; and am confi- 
dent life would not have long been preferved, unlefs they had 
been foon diminifhed or removed by the univerfal convulfion of 
the voluntary motions, or by temporary madnefs. 
In fome of the unfortunate patients I have obferved, the pain 
has rifen to an inexpreflible degree, as above defcribed, before 
the convulfions have fupervened ; and which were preceded by 
fereaming, and grinning; in others, as in the common epilepfy, 
the convulfion has immediately fucceeded the commencement of 
the difagreeable fenfations; and as a ftupor frequently fucceeds 
the convulfions, they only feemed to remember that a pain at the 
ftomach preceded the fit, or fome other uneafy feel; or more 
frequently retained no memory at all of the immediate caufe of 
the paroxyfm. But even in this kind of epilepfy, where the pa- 
tient does not recollect any preceding pain, the paroxyfms gen- 
erally are preceded by a quivering motion of the under jaw, 
with a biting of the tongue; the teeth afterwards become preff- 
ed together with vehemence, and the eyes are then convulfed, 
before the commencement of the univerfal convulfion 5 which 
are all efforts to relieve pain. 
The reafon why thefe convulfive motions are alternately exerted 
and remitted was mentioned above, and in Se<ft. XII. 1. 3. 
when the exertions are fuch as give a temporary relief to the 
pain, which excites them, they ceafe for a time, till the pain is 
again perceived; and then new exertions are produced for its 
relief. We fee daily examples of this in the loud reiterated 
laughter of fome people ; the pleafurable fenfation, which ex- 
cites this laughter, arifes for a time fo high as to change its name 
and become painful: the convulfive motions of the refpiratory 
mufcle^ 332 
DISEASES 
Sect. XXXIV. i. 4. 
mufcles relieve the pain for a time ; we are, however, unwil- 
ling to lofe the pleafure, and prefently put a flop to this exer- 
tion, and immediately the pleafure recurs, and again as inflantly 
rifes into pain. All of us have felt the pain of immoderate 
laughter; children have been tickled into convulfions of the 
whole body ; and others have died in the aft of laughing; 
probably from a paralyfis fucceeding the long continued aftions 
of the mufcles of refpiration. 
Hence we learn the reafon, why children, who are fo eafdy 
excited to laugh by the tickling of other people's fingers, cannot 
tickle themfelves into laughter. The exertion of their hands in 
the endeavour to tickle themfelves prevents the neceffity of any 
exertion of the refpiratory mufcles to relieve the excefs of pleaf- 
urable affeftion. See Seft. XVII. 3. 5. 
Chryfippus is recorded to have died laughing, when an afs 
was invited to fup with him. The fame is related of one of the 
popes, who, when he was ill, faw a tame monkey at his bed-fide 
put on the holy tiara. Hall.. Phyf. T. III. p. 306. 
There are inftances of epilepfy being produced by laughing 
recorded by Van Swieten, T. III. 402 and 308. And it is well 
known, that many people have died inflantaneoufly from the 
painful excefs of joy, which probably might have been prevent- 
ed by the exertions of laughter. 
Every combination of ideas, which we attend to, occafions 
pain or pleafure ; thofe which occafion pleafure, furnifh either 
focial or felfifh pleafure, either malicious or friendly, or lafcivi- 
ous, or fublime pleafure; that is, they give us pleafure mixed 
with other emotions, or they give us unmixed pleafure, without 
occafioning any other emotions or exertions at the fame time. 
This unmixed pleafure, if it be great, becomes painful, like all 
other animal motions from ftimuli of every kind; and if no 
other exertions are occafioned at the fame time, we ufe the ex- 
ertion of laughter to relieve this pain. Hence laughter is occa- 
fioned by fuch wit as excites fimply pleafure without any other 
emotion, fuch as pity, love, reverence. For fublime ideas are 
mixed with admiration, beautiful ones with love, new ones with 
furprife ; and thefe exertions of our ideas prevent the aftion of 
laughter from being neceflary to relieve the painful pleafure 
above defcribed. Whence laughable wit confifts of frivolous 
ideas, without connexions of any confequence, fuch as puns on 
words, or on phrafes, incongruous junftions of ideas j on which 
account laughter is fo frequent in children. 
Unmixed pleafure lefs than that, which caufes laughter, caufes 
Deep, as in finging children to deep, or in flight intoxication from 
wine or food. See Seft. XVIII. 12. 
5- Sect. XXXIV. i. 5. 
OF VOLITION. 
333 
If the pains, or difagreeable fenfations, above defcribed do 
not obtain a temporary relief from thefe convulfive exertions of 
the mufcles, thofe convulfive exertions continue without remif- 
fion, and one kind of catalepfy is produced. Thus when a nerve 
or tendon produces great pain by its being inflamed or wounded, 
the patient fets his teeth firmly together, and grins violently, to 
diminifh the pain ; and if the pain is not relieved by this exer- 
tion, no relaxation of the maxillary mufcles takes place, as in 
the convulfions above defcribed, but the jaws remain firmly 
fixed together. This locked jaw is the molt frequent inllance 
of cataleptic fpafm, becaufe we are more inclined to exert the 
mufcles fubfervicnt to maftication from their early obedience to 
violent efforts of volition. 
But in the cafe related in Seif. XIX. on Reverie, the catalep- 
tic lady had pain in her upper teeth ; and prefling one of her 
hands vehemently againft, her cheek bone to diminifh this pain, 
it remained in that attitude for about half an hour twice a day, 
till the painful paroxyfm was over. 
I have this very day feen a young lady in this difeafe, (with 
which file has frequently been afflicted ;) fhe began to-day with 
violent pain fhooting from one fide of the forehead to the occi- 
put, and after various druggies lay on the bed with her fingers 
and wrifts bent and Iliff for about two hours ; in other refpeCts 
fhe feemcd in a fyncope with a natural pulfe. She then had in- 
tervals of pain and of fpafm, and took three grains of opium 
every hour till fhe had taken nine grains, before the pains and 
fpafm ceafed. 
There is, however, another fpecies of fixed fpafm, which dif- 
fers from the former, as the pain exifts in the contracted mufcle, 
and would feem rather to be the confequence than the caufe of 
the contraCiion, as in the cramp in the calf of the leg, and in 
many other parts of the body. 
In thefe fpafms it fhould feem, that the mufcle itfelf is firft 
thrown into contraCtion by fome difagreeable fenfation, as of 
cold ; and that then the violent pain is produced by the great 
contraCiion of the mufcular fibres extending its own tendons, 
which are faid to be fenfible to extenfion only ; and is further 
explained in SeCt. XVIII. 15. 
6. Many inltances have been given in this work, where after 
violent motions excited by irritation, the organ has become qui- 
efcent to lefs, and even to the great irritation, which induced it 
into violent motion; as after looking long at the fun or any 
bright colour, they ceafe to be feen ; and after removing from 
bright day-light into a gloomy room, the eye cannot at firft per- 
ceive the objeCls, which Simulate it lefs. Similar to this is the 
' fyncope, 334 
DISEASES 
Sect. XXXIV. 1. 7; 
fyncope, which fucceeds after the violent exertions of our vol- 
untary motions, as after epileptic fits, for the power of volition 
adts in this cafe as the ftimulus in the other. This fyncope is a 
temporary palfy, or apoplexy, which ceafes after a time, the muf- 
cles recovering their power of being excited into action by the 
efforts of volition ; as the eye in the circumftance above men- 
tioned recovers in a little time its power of feeing objects in a 
gloomy room; which were invifible immediately after coming 
out of a (tronger light. This is owing to an accumulation of 
fenforia! power during the inaction of thofe fibres, which were 
before accuftomed to perpetual exertions, as explained in Se<£l. 
XII. 7. i. A (lighter degree of this difeafe is experienced by 
every one after great fatigue, when the mufcles gain fuch inabili- 
ty to further a&ion, that we are obliged to reft them for a while, 
or to fummon a greater power of volition to continue their 
motions. 
In all the fyncopes, which I have feen induced after convul- 
Cve fits, the pulfe has continued natural, though the organs of 
fenfe, as well as the locomotive mufcles, have ceafed to perform 
their funflions; for it is neceffary for the perception of objects, 
that the external organs of fenfe fliould be properly excited by 
the voluntary power, as the eye-lids mull be open, and perhaps 
the mufcles of the eye put into afiion to diftend, and thence 
give greater pellucidity to the cornea, which in fyncope, as in 
death, appears flat and lefs tranfparent. The tympanum of the 
ear alfo feems to require a voluntary exertion of its mufcles, to 
gain its due tenfion, and it is probable the other external organs 
of fenfe require a fimilar voluntary exertion to adapt them to 
the diftinff perception of objects. Hence in fyncope as in fleep, 
as the power of volition is fufpended, no external objects are 
perceived. See Seft. XVIII. 5. During the time which the 
patient lies in a fainting fit, the fpirit of animation becomes ac- 
cumulated ; and hence the mufcles in a while become irritable 
bv their ufual ftimulation, and the fainting fit ceafes. See Seft. 
XII. 7. 1. 
7. If the exertion of the voluntary motions has been {till more 
energetic, the quiefcence, which fucceeds, is fo complete, that 
they cannot again be excited into aition by the efforts of the 
will. In this manner the palfy, and apoplexy (which is an uni- 
verfal palfy) are frequently produced after convulfions, or other 
violent exertions ; of this I fhall add a few inftances. 
Platnerus mentions fome, who have died apoplectic from vio- 
lent exertions in dancing ; and Dr. Mead, in his efl'ay on Poi- 
fons, records a patient in the hvdrophobia, who at one effort 
broke the cords which bound him, an*d at the fame inftant ex- 
pired. Sect. XXXIV. 1.7. 
OF VOLITION. 
335 
pired. And it is probable, that thofe, who have expired from 
immoderate laughter, have died from this paralyfis confequent 
to violent exertion. Mrs. Scott of Stafford was walking in her 
garden in perfeCl health with her neighbour Mrs. j the lat- 
ter accidentally fell into a muddy rivulet, and tried in vain to 
difengage herfelf by the afliftance of Mrs. Scott's hand. Mrs. 
Scott exerted her utmoft power for many minutes, firft to affilb 
her friend, and next to prevent herfelf from being pulled into 
the morafs, as her diftreffed companion would not difengage 
her hand. After other afliftance was procured by their united 
fcreams, Mrs. Scott walked to a chair about twenty yards from 
the brook, and was feized with an apoplectic ftroke : which 
continued many days, and terminated in a total lofs of her right 
arm, and her fpeech ; neither of which fhe ever after perfectly 
recovered. 
It is faid, that many people in Holland have died after Ikating 
too long or too violently on their frozen canals ; it is probable 
the death of thefe, and of others, who have died fuddenly in 
fwimming, has been owing to this great quiefcence or paralyfis; 
which has fucceeded very violent exertions, added to the con- 
comitant cold, which has had greater effeCt after the fuffcrers 
had been heated and exhaufted by previous exercife. 
I remember a young man of the name of Nairne at Cambridge, 
who walking on the edge of a barge fell into the river. His 
coufin and fellow-ftudent of the fame name, knowing the other 
could not fwim, plunged into the water after him, caught him. 
by his clothes, and approaching the bank by a vehement exertion 
propelled him fafe to the land, but that inftant, feized, as was 
fuppofed, by the cramp, or paralyfis, funk to rife no more. The 
reafon why the cramp of the mufcles, which compofe the calf 
of the leg, is fo liable to affeCt fwimmers, is, becaufe thefe muf- 
cles have very weak antagonifts, and are in walking generally 
elongated again after their contraCtion by the weight of the body 
on the ball of the toe, which is very much greater than the re- 
fiftance of the water in fwimmjng. See Section XVIII. 15. 
It does not follow that every apopleCtic or paralytic attack is 
immediately preceded by vehement exertion; the quiefcence, 
which fucceeds exertion, and which is not fo great as to be term- 
ed paralyfis, frequently recurs afterwards at certain periods ; 
and by other caufes of quiefcence, occurring with thofe periods, 
as was explained in treating of the paroxyfms of intermitting 
fevers; the quiefcence at length becomes fo great as to be in- 
capable of again being removed by the efforts of volition, and 
complete paralyfis is foriped. SeeSeClion XXXII. 3. 2. 
Many of the paralytic patients, whom I have feen, have evi- 
dently 336 
DISEASES 
Sect. XXXIV. 2. 1. 
dently had difeafed livers from the too frequent potation of 
fpirituous liquors; tome of them have had the gutta rofea on 
their faces and breafts ; which has in fome degree receded either 
fpontaneoufly, or by the ufe of external remedies, and the para- 
lytic ftroke has fucceeded ; and as in feveral perfons, who have 
drunk much vinous fpirits, I have obferved epileptic fits to com- 
mence at about forty or fifty years of age, without any heredita- 
ry taint, from the ftimulus, as I believed, of a difeafed liver ; I 
was induced to afcribe many paralytic cafes to the fame fource ; 
which were not evidently the effect of age, or of unacquired de- 
bility. And the account given before of dropfies, which very 
frequently are owing to a paralyfis of the abforbent fyftem, and 
are generally attendant on free drinkers of fpirituous liquors, 
confirmed me in this opinion. 
The difagreeable irritation of a difeafed liver produces exer- 
tions and confequent quiefcence; thefe by the accidental con- 
currence of other caufes of quiefcence, as cold, folar or lunar 
periods, inanition, the want of their ufual portion of fpirit of 
wine, at length produces paralyfis. 
This is further confirmed by obferving, that the mufcles, we 
molt frequently, or moft powerfully exert, are molt liable to 
palfy ; as thofe of the voice and of articulation, and of thofe 
paralytics which I have feen, a much greater proportion have 
loft the ufe of their right arm ; which is fo much more gener- 
ally exerted than the left. 
I cannot difmifs this fubject without obferving, that after a 
paralytic ftroke, if the vital powers are not much injured, the 
patient has all the movements of the affected limb to learn over 
again, juft as in early infancy ; the limb is firft moved by the 
irritation of its mufcles, as in ftretching, (of which a cafe was 
related in Section VII. i. 3.) or by the electric concuffion ; 
afterwards it becomes obedient to fenfation, as in violent danger 
or fear ; and laftly, the mufcles become again affociated with 
volition, and gradually acquire their ufual habits of acting to- 
gether. 
Another phenomenon in palfies is, that when the limbs of one 
fide are difabled, thofe of the other are in perpetual motion. 
This can only be explained from conceiving that the power of 
motion, whatever it is, or wherever it refides, and which is capa- 
ble of being exhaufted by fatigue, and accumulated in reft, is 
now lefs expended, whilft one half of the body is incapable of 
receiving its ufual proportion of it, and is hence derived with 
greater eafe or in greater abundance into the limbs, which re- 
main unaffected. 
II. 1. The excefsor defect of voluntary exertion produces 
fimilar Sect. XXXIV. 2. 2. 
OF VOLITION. 
337 
Similar cflecTs upon the fenfual motions, or ideas of the mind, as 
thofe already mentioned upon the mufcular fibres. Thfis when 
any violent pain, arifing from the defeat of fome peculiar ftimu- 
lus, exifts either in the mufcular or fenfual fyftems of fibres, and 
which cannot be removed by acquiring the defective ftimulus; 
as in fome conftitutions convulfions of the mufcles are produced 
to procure a temporary relief, fo in other conftitutions vehement 
voluntary exertions of the ideas of the mind are produced for 
the fame purpofe ; for during this exertion, like that of the muf- 
cles, the pain either vanishes or is diminifhed : this violent ex- 
ertion conftitutes madnefs 5 and in many cafes I have feen the 
madnefs take place, and the convulfions ceafe, and reciprocally 
the madnefs ceafe, and the convulfions fupervene. See Section 
III. 5. 8. 
2. Madnefs is diftinguifhable from delirium, as in the latter 
the patient knows not the place where he refides, nor the per- 
fons of his friends or attendants, nor is confcious of any external 
objects, except when fpoken to with a louder voice, or ftimu- 
lated with unufual force, and even then he foon relapfes into a 
ftate of inattention to every thing about him. Whilft in the 
former he is perfetlly fenfible to every thing external, but has 
the voluntary powers of his mind intenfely exerted on fome par- 
ticular object of his defire or averfion, he harbours in his 
thoughts a fufpicion of all mankind, left they fhould counteract 
his defigns; and while he keeps his intentions, and the motives 
of his actions profoundly fecret; he is perpetually ftudying the 
means of acquiring the objed: of his wifh, or of preventing or 
revenging the injuries he fufpects. 
3. A late French philosopher, Mr. Helvetius, has deduced al- 
moft all our actions from this principle of their relieving us 
from the ennui or t tedium vitae 5 and true it is, that our defires 
or averfions are the motives of all our voluntary actions ; and 
human nature feems to excel other animals in the more facile 
ufe of this voluntary power, and on that account is more liable 
to infanity than other animals. But in mania this violent exer- 
tion of volition is expended on miftaken objects, and would not 
be relieved, though we were to gain or efcape the objects, that 
excite it. Thus I have feen two inftances of madmen, who con- 
ceived that they had the itch, and Several have believed they had 
the venereal infection, without in reality having a fymptom of 
either of them. They have been perpetually thinking upon this 
Subject, and fome of them were in vain Salivated with defign of 
convincing them to the contrary. 
4. In the minds of mad people thofe volitions alone exift, 
which are unmixed with fenfation; immoderate fufpicion is 
Voj,. I. U v generally 338 
DISEASES 
Sect. XXXIV. 2. 
generally the firft fymptom, and want of fhame, and want of 
delicacy about cleanlinefs. Sufpicion is a voluntary exertion of 
the mind arifing from the pain of fear, which it is exerted to 
relieve : (hame is the name of a peculiar difagreeable fenfation, 
fee Fable of the Becs, and delicacy about cleanlinefs arifes from 
another difagreeable fenfatron. And therefore are not found in 
the minds of maniacs, which are employed folely in voluntary 
Exertions. Hence the moft modeft women in this difeafe walk 
naked amongft men without any kind of concern, ufe obfcene 
difcourfe, and have no delicacy about their natural evacuations. 
5. Nor are maniacal people more attentive to their natural 
appetites, or to the irritations which furround them, except as far 
as may relpect their fufprcions or defigns ; for the violent and 
perpetual exertions of their voluntary powers of mind prevent 
their perception of almoft every other object, either of irritation 
or of fenfation. Hence it is that they bear cold, hunger, and fa- 
tigue, with much greater pertinacity than in their fober hours, and 
are lefs injured by them in refpedf to their general health. Thus 
it is aflerted by hiftorians, that Charles the Twelfth of Sweden 
flept on the fnow, wrapped only in his cloak, at the fiege of 
Frederickftad, and bore extremes of cold and hunger, and fatigue, 
under which numbers of his foldiers perifhed ; becaufe the king 
was infane with ambition, but the foldier had no fuch powerful 
ftimulus to preferve his fyftem from debility and death. 
6. Befides the infanities arifing from exertions in confequencc 
of pain, there is alfo a plcafurable infanity, as well as a pleafura- 
ble delirium ; as the infanity of perfonal vanity, and that of re- 
ligious fanaticifm. When agreeable ideas excite into motion the 
fenforial power of fenfation, and this again caufes other trains of 
agreeable ideas, a conftant Rream of pleafurable ideas fucceeds, 
and produces pleafurable delirium. So when the fenforial power 
of volition excites agreeable ideas, and the pleafure thus produ- 
ced excites more volition in its turn, a conftant flow of agreea- 
ble voluntary ideas fucceeds; which when thus exerted in the 
extreme conftitutes infanity. 
Thus when our mufcular actions are excited by our fenfations 
of pleafure, it is termed play ; when they are excited by our 
volition, it is termed work ; and the former of thefe is attended 
with lets fatigue, becaufe the mufcular actions in play produce 
in their turn more pleafurable fenfation ; which again has the 
property of producing more mufcular action. An agreeable in- 
itance of this I faw this morning. A little boy, who was tired 
with walking, begged of bis papa to carry him. " Here," fays 
the reverend dodlor, " ride upon my gold-headed cane and 
the pleated child, putting it between his legs, gallopped away 
with Sect. XXXIV. 2. 7. 
OF VOLITION. 
339 
with delight, and complained no more of his fatigue. Here the 
aid of another fenforial power, that of pleafurable fenfation, fu- 
peradded vigour to the exertion of exhaulted volition. Which 
could otherwife only have been excited by additional pain, as by 
the lath of llavery. On this account where the whole fenforial 
power has been exerted on the contemplation of the promifed 
joys of heaven, the faints of all perfecuted religions have borne 
the tortures ofmartyrdom with otherwife unaccountable iirmnefs. 
7. There are fome difeafes, which obtain at leaft a temporary 
relief from the exertions of infanity ; many inftances of dropfies 
being thus for a time cured are recorded. An elderly woman 
labouring with afcites I twice faw relieved for fome weeks by 
infanity, the dropfy ceafed for feveral weeks, and recurred again 
alternating with the infanity. A man afflicted with difficult ref- 
piration on lying down, with very irregular pulfe, and ocdemar- 
tous legs, whom I faw this day, has for above a week been much 
relieved in refpetl to all thofe fymptoms by the acceffion of in- 
fanity, which is ihewn by inordinate fulpicion, and great anger. 
In cafes of common temporary anger the increafed action of 
the arterial fyltem is feen by the red fkin, and increafed pulfe, 
with the immediate increafe of mufcular activity. A friend of 
mine, when he was painfully fatigued by riding on hqrfeback, 
was accuftomed to call up ideas into his mind, which ufed to ex- 
cite his anger or indignation, and thus for a time at leaft relieved 
the pain of fatigue. By this temporary infanity, the effect of 
the voluntary power upon the whole of his fyftem was increafed ; 
as in the cafes of dropfy above mentioned, it would appear, that 
the increafed aftion of the voluntary faculty of the lenforium 
affected the abforbeiit fyftem, as well as the fecerning one. 
B. In refpeeft to relieving inflammatory pains, and removing 
fever, 1 have feen many inftances, as mentioned in Sedt. XII. 
2. 4. One lady, whom I attended, had twice at fome years in- 
terval a locked jaw, which relieved a pain on her fternum with 
peripneumony. Two other ladies I faw, who towards the end 
of violent peripneumony, in which they frequently loft blood, 
were at length cured by infanity fupervening. In the former 
the increafed voluntary exertion of the mufcles of the jaw, in the 
latter that of the organs cf fenfe, removed .the difeafe ; .that is, 
the difagreeable fenlation, which had produced the inflamma- 
tion, now excited the voluntary power, and thefe new voluntary 
exertions employed or expended the fuperabundant fenforial 
power, which had previoufly been exerted on the arterial fyftem, 
and caufed inflammation. 
Another cafe which I think worth relating, was of a young 
inan about twenty; he had laboured under an irritative fever 
with 340 
DISEASES 
Sect. XXXIV. 3. r. 
with debility for three or four weeks, with very quick and very 
feeble pulfe, and other ufual fymptoms of that fpecies of typhus, 
but at this time complained much and frequently of pain of his 
legs and feet. When thofe who attended him were nearly in 
defpair of his recovery, I obferved with pleafure an infanity of 
mind fupervene : which was totally different from delirium, as 
he knew his friends, calling them by their names, and the room 
in which he lay, but became violently fufpicious of his attend- 
ants, and calumniated with vehement oaths his tender mother, 
who fat weeping by his bed. On this his pulfe became flower 
and firmer, but the quicknefs did not for fome time intirely 
ceafe, and he gradually recovered. In this cafe the introduction 
of an increafed quantity of the power of volition gave vigour to 
thofe movements of the fyflem, which are generally only actu- 
ated by the power of irritation, and of aflbciation. 
Another cafe I recollect of a young man, about twenty-five, 
who had the fcarlet-fever, with very quick pulfe, and an univer- 
fal eruption on his ikin, and was not without reafon efteemed to 
be in great danger of his life. After a few days an infanity fu- 
pervened, which his friends miftook for delirium, and he gradu- 
ally recovered, and the cuticle peeled off. From thefe and a 
few other cafes I have always efteemed infanity to be a favoura- 
ble fign in fevers, and have cautioufly diftinguiflied it from de- 
lirium. 
III. Another mode of mental exertion to relieve pain, is by 
producing a train of ideas not only by the efforts of volition, as 
in infanity ; but by thofe of fenfation likewife, as in delirium 
and deep. This mental effort is termed reverie, or fomnambula- 
tion, and is defcribed more at large in SeCt. XIX. on that fub- 
je£E But I (hall here relate another cafe of that wonderful dif- 
eafe, which fell yefterday under my eye, and to which I have 
feen many analogous alienations of mind, though not exactly 
fimilarin all circumftances. But as all of them either began or 
terminated with pain or convulfion, there can be no doubt but 
that they are of epileptic origin, and conftitute another mode of 
mental exertion to relieve fome painful fenfation. 
i. Matter A. about nine years old, had been feized at feven 
every morning for ten days with uncommon fits, and had had 
flight returns in the afternoon. They were fuppofed to origi- 
nate from worms, and had been in vain attempted to be removed 
by vermifuge purges. As his fit was expeClcd at feven yefter- 
day morning, I faw him before that hour ; he was afleep, feemed 
free from pain, and his pulfe natural. About feven he began 
to complain of pain about his navel, or more to the left fide, 
and in a few minutes had exertions of his arms and legs like 
fwimming. Sect. XXXIV. 3. 2. 
OF VOLITION. 
341 
fwimming. He then for half an hour hunted a pack of hounds; 
as appeared by his hallooing, and calling the dogs by their names, 
and difcourfing with the attendants of the chafe, defcribing ex- 
actly a day of hunting, which (I was informed) he had witneffed 
a year before, going through all the molt minute circumftances 
of it calling to people, who were then prefent, and lamenting 
the abfence of others, who were then alfo abfent. After this 
feene he imitated, as he lay in bed, feme of the plays of boys, 
as fwimrning and jumping. He then lung an Englifh and then 
an Italian fong; part of which with his eyes open, and part with 
them clofed, but could not be awakened or excited by any vio- 
lence, which it was proper to ufe. 
After about an hour he came fuddenly to himfelf with ap- 
parent furprife, and feeined quite ignorant of any part of what 
had pafled, and after being apparently well for half an hour, he 
fuddenly fell into a great ftupor, with Hower pulfe than natural, 
and a flow moaning refpiration, in which he continued about 
another half hour, and then recovered. 
The fequel of this difeafe was favourable; he was directed 
one grain of opium at fix every morning, and then to rife out of 
bed ; at half paft fix he was directed fifteen drops of laudanum 
in a glafs of wine and water. The firft day the paroxyfm be- 
came fliorter, andlefs violent. The dofe of opium was increas- 
ed to one-half more, and in three or four days the fits left him. 
The bark and filings of iron were alfo exhibited twice a day ; 
and I believe the complaint returned no more. 
2. In this paroxyfm it mull be obferved, that he began with 
pain, and ended with ftupor, in both circumftances refernbling 
a fit of epilepfy. And that therefore the exertions both of mind 
and body, both the voluntary ones, and thofe immediately excited 
by pleafurable fenfation, were exertions to relieve pain. 
The hunting feene appeared to be rather an act of memory 
than of imagination, and was therefore rather a voluntary exertion, 
though attended with the pleafurable eagernefs, which was the 
confequence of thofe ideas recalled by recollection, and not the 
caufe of them. 
Thefe ideas thus voluntarily recollected were fucceeded by fen- 
fations of pleafure, though his fenfes were unaffected by the 
ftimuli of vifible or audible objects ; or fo weakly excited by 
them as not to produce fenfation or attention. And the pleaf- 
ure thus excited by volition produced other ideas and other mo- 
tions in confequence of the fenforial power of fenfation. 
Whence the mixed catenations of voluntary and fenfitive ideas 
and mufcular motions in reverie ; which, like every other kind 
of 342 
DISEASES 
Sect. XXXIV. 3. 3. 
of vehement exertion, contribute to relieve pain, by expending 
a large quantity of fenforial power. 
Thofe fits generally commence during fleep, from whence I 
fuppofe they have been thought to have fome connexion with 
fleep, and have thence been termed Somnambulifm; but their 
commencement during fleep is owing to our increafed excita- 
bility by internal fenfations at that time, as explained in Sect. 
XVIII. 14 and 15, and not to any fimilitude between reverie 
and fleep. 
3. I was once concerned for -a very elegant and ingenious 
young lady, who had a reverie on alternate days, which continu- 
ed nearly the whole day ; and as in her days of difeafe fhe took 
up the fame kind of ideas, which (he had converted about on 
the alternate day before, and could recollect nothing of them on 
her well day ; fhe appeared to her friends to poflefs two minds. 
This cafe alfo was of the epileptic kind, and was cured, with 
fome relapfes, by opium adminiftered before the commencement 
of the paroxyfm. 
4. Whence it appears, that the methods of relieving inflam- 
matory pains^ is by removing all ftimulus, as by venefe&ion, 
cool air, mucilaginous diet, aqueous potation, filence, darknefs. 
The methods of relieving pains from defeat of ftimulus is by 
fupplying the peculiar ftimulus required, as of food, or warmth. 
And the general method of relieving pain is by exciting into 
action fome great part of the fyftem for the purpofe of expend- 
ing a part of the fenforial power. This is done either by ex- 
ertion of the voluntary ideas and mufcles, as in infanity and 
convulsion; or by exerting both voluntary and fenfitive mo- 
tions, as in reverie ; or by exciting the irritative motions by 
wine or opium internally, and by the warm bath or blifters ex- 
ternally ; or laftly, by exciting the fenfitive ideas by good news, 
affe&ing ftories, or agreeable paflions. 
SECT. Sect. XXXV. 1. 1. 
4SSOCIATtoN. 
343 
SECT. XXXV. 
Diseases of association. 
I. I. Sympathy or confent of parts. Primary and fecondary parts 
of an affociated train of motions reciprocally affect each other. 
Parts of irritative trains of motion affebt each'other in four ways. 
Sympathies ofthefkin and fomach. Flufhing of the face after a 
meal. Eruption of the fmall-pox on the face. Chilnefs after a 
meal. 2. Vertigo from intoxication. 3. Abforplion from the 
lungs and pericardium by emetics. In vomiting the actions of the 
foniach are decreafed^ not increafid^ Digefiion flrengthened after 
an emetic. Vomiting from deficiency f fenforial power. 4. 
Dyfpnuea from cold bathing. Slow pulfe from digitalis. Death 
from gout in the fiomach. II. 1. Primary and fecondary parts 
of fenfitive afficiations affect each other. Pain from gall-flone, 
from urinary fione. Hemicrania. Painful epilepfy. 2. Gout 
and redfacefrom inflamed liver. Shingles from inflamed kidney. 
3. Coryza from cold applied to the feet. Hepatitis. 4. Pain of 
/boulders from inflamed liver. III. Difeafes from the affocia- 
tions of ideas. 
I. i. Many fynchronous and fuoceflive motions of out muf- 
cular fibres, and of our organs of fenfe, or ideas, become affoci- 
ated fo as to form indiflbluble tribes or trains of action, as fhewii 
in Scftion X. on Affociate Motions. Some conftitutions more 
eafily eftablifh thefe aflbciations, whether by voluntary, fenfitive, 
or irritative repetitions, and fome more eafily lofe them again, 
as fhewn in Section XXXI. on Temperaments. 
When the beginning of fuch a train of aftions becomes by 
any means difordered, the fucceeding part is liable to become 
dilturbed in confequence, and this is commonly termed fympa- 
thy or confent of parts by the writers of medicine. For the 
more clear underftanding of thefe fympathies we mult confider 
a tribe or train of actions as divided into two parts, and call one 
of them the primary or original motions, and the other the 
fecondary or fympathetic ones. 
The primary and fecondary parts of a train of irritative actions 
may reciprocally affeft each other in four different manners. 
I. They may both be exerted with greater energy than natural. 
2. The former may aft with greater, and the latter with lefs 
energy. 3. The former may aft with lefs, and the latter with 
greater energy. 4. They may both aft with lefs energy than 
natural. I Ihall now give an example of each kind of thefe 
modes 344 
DISEASES 
Sect. XXXV. i. 2. 
modes o£ aft ion, and endeavour to fhew, that though the pri- 
mary and fecondary parts of thefe trains or tribes of motion are 
connected by irritative aflbciation, or their previous habits of 
acting together, as defcribed in Sect. XX. on Vertigo. Yet 
that their acting with fimilar or diflimilar degrees of energy, 
depends on rhe greater or lefs quantity of fenforial power, which 
the primary part of the train expends in its exertions. 
The actions of the ftomach conftitute fo important a part of 
the aflbciations of both irritative and fenfitive motions, that it is 
faid to fympathize with ahnoft every part of the body j the firft 
example, which I fha.lt adduce to fhew that both the primary 
and fecondary parts of a train of irritative aflbciations of motion 
act with increafed energy, is taken from the confent of the fkin 
with this organ. When the action of the fibres of the ftomach 
is increafed, as by the itimulus of a full meal, the exertions of 
the cutaneous arteries of the face become increafed by their ir- 
ritative aflbciations with thofe of the ftomach, and a glow or 
fluihing of the face fucceeds. For the fmall veflels of the ikin' 
of the face having been more accuftomed to the varieties of ac- 
tion, from their frequent expofure to various degrees of cold and 
heat, become more eaffly excited into increafed action, than thofe 
of the covered parts of our bodies, and thus ack with more ener- 
gy from their irritative or fenfitive aflbciations with the ftom- 
ach. On this account in fmall-pox the eruption in confequence 
of the previous afFeftion of the ftomach breaks out a day fooner 
on the face than on the hands, and two days fooner than on the 
trunk, and recedes in fimilar times after maturation. 
But fecondly, in weaker conftitutions, that is, in thofe who 
poflefs lefs fenforial power, fo much of it is expended in the in- 
creafed actions of the fibres of the ftomach excited by the ftimu- 
lus of a meal, that a fenfe of chilnefs fucceeds inftead of the uni- 
verfal glow above mentioned ; and thus the fecondary part of 
the aflbeiated train of motions is diminifhed in energy, in confe- 
quence of the increafed activity of the primary part of it. 
2. Another inftance of a fimilar kind, where the fecondary 
part of the train ails with lefs energy in confequence of the 
greater exertions of the primary part, is the vertigo attending in- 
toxication ; in this circumftance fo much fenforial power is ex- 
pended on the ftomach, and on its neareft or more ftrongly aflb- 
eiated motions, as thofe of the fubcutaneous veflels, and proba- 
bly of the membranes of fome internal vifeera, that the irritative 
motions of the retina become imperfectly exerted from defi- 
ciency of fenforial power, as explained in Sect. XX. and XXL 
3. on Vertigo and on Drunkenncfs, and hence the ftaggering ine- 
briate cannot completely balance himlelf by fuch indiltinCt vifion. 
3- An Sect. XXXV. i. 3. 
OF ASSOCIATION. 
345 
3« An inftance of the third circumftance, where the primary 
part of a train of irritative motions a&s with lefs, and the fec- 
ondary part with greater energy, may be obferved by making 
the following experiment. If a perlon lies with his arms and 
fhoulders out of bed, till they become cold, a temporary coryza 
or catarrh is produced ; fo that the paflage of the noftrils be- 
comes totally obftrudled ; at leaft this happens to many people ; 
and then on covering the arms and fhoulders, till they become 
warm, the paflage of the noftrils ceafes again to be obftrudled, 
and a quantity of mucus is difcharged from them. In this cafe 
the quiefcence of the veflels of the Ikinof the arms and (boul- 
ders, occafioned by expofure to cold air, produces by irritative 
aflbciation an increafed aftion of the veflels of the membrane of 
the noftrils ; and the accumulation of fenforial power during the 
torpor of the arms and fhoulders is thus expended in producing 
a temporary coryza or catarrh. 
Another inftance maybe adduced from the fympathyor con- 
fent of the motions of the ftomach with other more diftant links 
of the very extenfive tribes or trains of irritative motions aflbci- 
ated with them, defcribed in Scdl. XX. on Vertigo. When 
the actions of the fibres of the ftomach are diminifhed or invert- 
ed, the actions of the abforbcnt veflels, which take up the mucus 
from the lungs, pericardium, and other cells of the body, be- 
come increafed, and abforb the fluids accuhrulated in them with 
greater avidity, as appears from the exhibition of foxglove, anti- 
mony, or other emetics, in cafes of anafarca, attended with un- 
equal pulfe and difficult refpiration. 
That the act of naufea and vomiting is a decreafed exertion 
of the fibres of the ftomach may be thus deduced ; when an 
emetic medicine is adminiftered, it produces the pain of ficknefs, 
as a difagreeable tafte in the mouth produces the pain of naufea ; 
thefe pains, like that of hunger, or of cold, or like thofe, which 
are ufually termed nervous, as the head-ach or hemicrania, do 
not excite the organ into greater aft ion ; but in this cafe I im- 
agine the pains of ficknefs or of naufea counteract or deftroy 
the pleafurable fenfation, which feems neceflary to digeftion, as 
(hewn in SeCt. XXXIII. I. i. The periftaltic motions of the 
fibres of the ftomach become enfeebled by the want of this 
flimulus of pleafurable fenfation, and in confequence ftop for a 
time, and then become inverted ; for they cannot become invert- 
ed without being previoufly flopped. Now that this inverfion 
of the trains of motion of the fibres of the ftomach is owing to 
the deficiency of pleafurable fenfation is evinced from this cir- 
cumftance, that a naufeous idea excited by words will produce 
vomiting as effectually as a naufeous drug. 
Vol. I. W w 346 
DISEASES 
Sect. XXXV. 1.4. 
Hence it appears, that the aft of naufea or vomiting expends 
lefs fenforial power than the ufual periftaltic motions of the 
ftomach in the digeftion of our aliment; and that hence there 
is a greater quantity of fenforial power becomes accumulated 
in the fibres of the ftomach, and more of it in confequence to 
fpare for the aftion of thofe parts of the fyftem, which are thus 
aflbciated with the ftomach, as of the whole abforbent feries of 
veifels, and which are at the fame time excited by their ufual 
ftimuli. 
From this we can underftand, how after the operation of an 
emetic the ftomach becomes more irritable and fenfible to the 
ftimulus, and the pleafure of food ; fmce as the fenforial power 
becomes accumulated during the naufea and vomiting, the digef- 
tive power is afterwards exerted more forcibly for a time. It 
ihould, however, be here remarked, that though vomiting is in 
general produced by the defeft of this ftimulus of pleafurable 
fenfation, as when a naufeous drug is adminiftered j yet in long- 
continued vomiting, as in fea-ficknefs, or from habitual dram- 
drinking, it arifes from deficiency of fenforial power, which in 
the former cafe is exhaufted by the increafed exertion of the ir- 
ritative ideas of vifion, and in the latter by the frequent applica- 
tion of an unnatural ftimulus. 
4. An example of the fourth eircumftance above mentioned, 
where both the primary and fecondary parts of a train of mo- 
tions proceed with energy lefs than natural, may be obferved in 
the dyfpnoea, which occurs in going into a very cold bath, and 
which has been dcfcribed and explained in Scft. XXXII. 3. 2. 
And by the increafed debility of the pulfations of the heart 
and arteries during the operation of an emetic. Secondly, from 
the flownefs and intermiffion of the pulfations of the heart from 
the inceffant efforts to vomit oceafioned by an over-dofe of dig- 
italis. And thirdly, from the total ftoppage of the motions of 
the heart, or death, in confequence of the torpor of the ftomach, 
when affiefted with the commencement or cold paroxyfm of the 
gout. See Soft. XXV. 17. 
II. 1. The primary and fecondary parts of the trains of fen- 
fitive affociation reciprocally affeft each other in different man- 
ners. 1. The increafed fenfation of the primary part may ceafe, 
when that of the fecondary part commences. 2. The increafed 
aftion of the primary part may ceafe, when that of the fecondary 
part commences. 3. The primary part may have increafed fen- 
fation, and the fecondary part increafed aftion. 4. The pri- 
mary part may have increafed aftion, and the fecondary part in- 
creafed fenfation. 
Examples of the firft mode, where the increafed fenfation of Sect. XXXV. 2. 1, 
OF ASSOCIATION. 
347 
the primary part of a train of fenfitive affociation ceafes, when 
that of the fecondary part commences, are not unfrequent; as 
this is the general origin of thofe pains, which continue fome 
time without being attended with inflammation, fuch as the pain 
at the pit of the ftomach from a hone at the neck of the gall- 
bladder, and the pain of lirangury in the glans penis from a ftc-ne 
at the neck of the urinary bladder. In boththefe cafes the part, 
which is affected fecondarily, is believed to be much more fen- 
£ble than the part primarily affected, as defcribed in the cata- 
logue of difeafes, Clafs II. r. j. 11. and IV. 2. 2. 2. and IV. 
2. 2. 4. 
The hemicrania, or nervous head-ach, as it is called, when it 
originates from a decaying tooth, is another difeafe of this kind ; 
as the pain of the carious tooth always ceafes, when the pain 
over one eye and temple commences. And it is probable, that 
the violent pains, which induce convulfions in painful epilepGes, 
are produced in the fame manner, from a more .fepfible part 
fympathizing with a difeafed one of lefs fenGbility. See Cata- 
logue of difeafes, Clafs IV. 2. 2. 8. and IIJ. 1. 1. 6. 
The laR tooth, or dens fapientiap, of the upper jaw mo/l fre- 
quently decays firfl, and is liable to produce pain over the eye 
and temple of that fide. The laft tooth of the under jaw is alfo 
liable to produce a fimilar hemicrania, when it begins to decav. 
When a tooth in the upper jaw is the caufe of tire headach, a 
{lighter pain is fometimes perceived on the cheek-bone. And 
when a tooth in the lower jaw is the caufe of headach, a pain 
fometimes affects the tendons of the mufcles of the neck, which 
are attached near the jaws. But the clavus hyftericup, or pain 
about the middle of the parietal bone on one fide of the head, I 
have feen produced by the fecond of the molares,or grinders, of 
the under jaw; of which I fhall relate the following cafe. See 
Clafs IV. 2. 2. 8. 
Mrs. , about 30 years of age, was feized with great pain 
about the middle of the right parietal bone, which had continu- 
ed a whole day before I faw her, and was fo violent as to threat- 
en to occafion convulfions. Not being able to detedt a decay- 
ing tooth, or a tender one, by examination with my eye, or by 
ftriking them with a tea-fpoon, and fearing bad confequences 
from her tendency to convulfion, I advifed her to extract the 
laft tooth of the under-jaw on the affected fide; which was 
done without any good effect. She was then directed to lofe 
blood, and to take a brifk cathartic; and after that had operated, 
about 6s drops of laudanum were given her, with large doles 
•f bark ; by which the pain was removed. In about a fortnight 
Ihe took a cathartic medicine by ill advice, and the pain returned 
with 348 
DISEASES 
Sect. XXXV. 2. i. 
with greater violence in the fame place; and, before I could ar- 
rive, as the lived 30 miles from me, the fuffered a paralytic 
ftroke; which affected her limbs and her face on one fide, and 
relieved the pain of her head. 
About a year afterwards I was again called to her on account 
of a pain, as violent as before, exactly on the fame part of the 
other parietal bone. On examining her mouth I found the fecond 
molaris of the under-jaw on the fide before affected was now 
decayed, and concluded, that this tooth had occafioned the ftroke 
of the palfy by the pain and confeq uent exertion it had caufed. 
On this account I earneftly entreated her to allow the found mo- 
laris of the fame jaw oppofite to the decayed one to be extract- 
ed ; which was forthwith done, and the pain of her head im- 
mediately ceafed, to the aftoniihment of her attendants. 
In the cafes above related of the pain exifting in a part dif- 
tant from the feat of the difeafe, the pain is owing to defect of 
the ufual motions of the painful part. This appears from the 
coldnefs, palenefs, and emptinefs of the affected vefi'els, or of 
the extremities of the body in general, and from their being no 
tendency to inflammation. The increafed aCtion of the prima- 
ry part of thefe aflbeiated motions, as of the hepatic termination 
of the bile-duft from the ftimulus of a gall-ftone, or of the inte- 
rior termination of the urethra from the ftimulus of a (tone in 
the bladder, or laftly, of a decaying tooth in hemicrania, de- 
prives the fecondary part of thefe aflbeiated motions, namely, 
the exterior terminations of the bile-duct or urethra, or the pain- 
ed membranes of the head in hemicrania, of their natural fhare 
of fenforial power: and hence the fecondary parts of thefe fen- 
fitive trains of aflbeiation become pained from the deficiency of 
their ufual motions, which is accompanied with deficiency of 
fecretions and of heat. See SeCt. IV. 5. XII. 5. 3. XXXIV. 1. 
Why does the pain of the primary part of the aflbeiation 
ceafe, when that of the fecondary part commences ? This is a 
queftion of intricacy, but perhaps not inexplicable. The pain 
of the primary part of thefe aflbeiated trains of motion was ow- 
ing to too great ftimulus, as of the ftone at the neck of the blad- 
der, and was confequently caufed by too great action of the 
pained part. This greater action than natural of the primary 
part of thefe aflbeiated motions, by employing or expending the 
fenforial power of irritation belonging to the whole aflbeiated 
train of motions, occafioned torpor, and confequent pain in 
the fecondary part of the aflbeiated train ; which was poflefled 
of greater fenfibility than the primary part of it. Now the great 
pain of the fecondary part of the train, as foon as it commences, 
employs or expends the fenforial power of fenfat-ion belonging 
to Sect. XXXV. 2. 2. 
OF ASSOCIATION. 
349 
to the whole affociated train of motions ; and in confequence 
the motions of the primary part, though increafed by the ftimu- 
lus of an extraneous body, ceafe to be accompanied with pain 
or fenfation. 
If this mode of reafoning be juft it explains a curious fafl, 
why when two parts of the body are ftrongly ftimulated, the 
pain is only felt in one of them, though it is poflible by volunta- 
ry attention it may be alternately perceived in them both. In 
the fame manner, when two new ideas are prefented to us from 
the ftimulus of external bodies, we attend to but one of them at 
a time. In other words, when one fet of fibres, whether of the 
mufcles or organs of fenfe, contrafl; fo ftrongly as to excite 
much fenfation ; another fet of fibres contrafling more weakly 
do not excite fenfation at all, becaufe the fenlbrial power of fen- 
fation is pre-occupied by the firft fet of fibres. So we cannot 
will more than one effefl at once, though by affociations previ- 
oufly formed we can move many fibres in combination. 
Thus in the inftances above related, the termination of the 
bile duct in the duodenum, and the exterior extremity of the 
urethra, are more fenfible than their other terminations. When 
thefe parts are deprived of their ufual motions by deficiency of 
fenforial power, as above explained, they become painful ac- 
cording to law the fifth in Seflion IV. and the lefs pain orig- 
inally excited by the ftimulus of concreted bile, or of a ftone at 
their other extremities cafes to be perceived. Afterwards, how- 
ever, when the concretions of bile, or the ftone in the urinary 
bladder, become more numerous or larger, the pain from their 
increafed ftimulus becomes greater than the affociated pain ; and 
is then felt at the neck of the gall bladder or urinary bladder ; 
and the pain of the glans penis, or at the pit of the ftomach, 
ceafes to be perceived. 
2. Examples of the fecond mode, where the increafed aflion 
of the primary part of a train of fenfitive affociation ceafes, when 
that of the fecondary part commences, are alfo not unfrequent ; 
as this is the ufual manner of the tranflation of inflammations 
from internal to external parts of the fyftem, fuch as when an 
inflammation of the liver or ftomach is tranflated to the mem- 
branes of the foot, and forms the gout; or to the fkin of the 
face, and forms the rofy drop ; or when an inflammation of the 
membranes of the kidneys is tranflated to the Ikin of the loins, 
and forms one kind of herpes, called flfingles; in thefe cafes by 
whatever caufe the original inflammation may have been pro- 
duced, as the fecondary part of the train of fenfitive affociation 
is more fenfible, it becomes exerted with greater violence than 
the firft part of it; and by both its increafed pain, and the in- 
crealed 350 
DISEASES 
Sect. XXXV. 2. 3. 
creafed motion of its fibres, fo far diminifhes or exhaufts the fen- 
forial power of fenfation ; that the primary part of the train be- 
ing lefs fenfible ceafes both to feel pain, and to abt with un- 
natural energy. 
3. Examples of the third mode, where the primary part of a 
train of fenfitive aflbeiation of motions may experience increafed 
fenfation, and the fecondary part increafed action, are likewife 
not unfrequent $ as it is in this manner that molt inflammations 
commence. Thus, after (landing fome time in fnow, the feet 
become affefted with the pain of cold, and a common coryza, 
or inflammation of the membrane of the noftrils, fucceeds. It 
is probable that the internal inflammations, as pleurifies, or he- 
patitis, which are produced after the cold paroxyfm of fever, 
originate in the fame manner from the fympathy of thofe parts 
with fome others, which were previoufly pained from quief- 
cence; as happens to various parts of the fyltem during the cold 
fits of fevers. Ip thefe cafes it would feem, that the fenforial 
power of fenfation becomes accumulated during the pain of cold, 
as the torpor of the veflels occafioned by the defeat of heat con- 
tributes to the increafe or accumulation of the fenforial power of 
irritation, and that both thefe become exerted on fome internal 
part, which war. not rendered torpid by the cold which affected 
the external parts, nor by its aflbeiation with them ; or which 
fooner recovered its fenfibility. This requires further con- 
fideration. 
4. An example of the fourth mode, or where the primary 
part of a fenfitive aflbeiation of motions may have increafed ac- 
tion, and the fecondary part increafed fenfation, may be taken 
from the pain of the fhoulder, which attends inflammation of the 
membranes of the liver, fee Clafs IV. 2. 2. 9.; in this circum- 
llance fo much fenforial power feems to be expended in the vio- 
lent "aftions and fenfations of the inflamed membranes of the 
liver, that the membranes aflbeiated with them become qtjief- 
cent to their ufual ftimuli, and painful in confequence. 
There may be other modes in which the primary and feconda- 
ry parts of the trains of aflbeiated fenfitive motions may recipro- 
cally affetSl each other, as may be feen by looking over Clafs IV. 
in the catalogue of difeafes ; all which may probably be refolved 
into the plus and minus of fenforial power, but we have not yet 
had fuflicient obfervations made upon them with a view to this 
doctrine. 
III. The aflbeiated trains of our ideas may have fympathies, 
and their primary and fecondary parts atFe£t each other in fome 
manner fimilar to thofe above defcribed ; and may thus occafion 
various curious phenomena not yet adverted te, befides thofe ex- 
plained Sect. XXXV. 3. 1. 
OF ASSOCIATION. 
351 
plained in the Sections on Dreams, Reveries, Vertigo, and 
Drunkennefs ; and may thus difturb the deductions of our rea- 
fonings, as well as the ftreams of our imaginations; prefent us 
with falfe degrees of fear, attach unfounded value to trivial cir- 
cumftances; give occafion to our early prejudices and antipa- 
thies ; and thus embarrafs the happinefs of our lives. A copi- 
ous and curious harveft might be reaped from this province of 
fcience, in which, however, 1 (hall not at prefent wield my 
fickle. 
SECT 352 
PERIODS 
Sect. XXXVI. 1. 1. 
SECT. XXXVI. 
OF THE PERIODS OF DISEASES. 
I. Mufcles excited by volition foon ceafe to contrafl, or by fenfation, 
or by irritation, owing to the exhaufion of fenforial power. Muf- 
cles fubjefted to lefs ftimulus have their fenforialpower accumula- 
ted. Hence the periods of feme fevers. Want of irritability 
after intoxication. II. I. Natural actions catenated with daily 
habits of life. 2. With folar periods. Periods of feep. Of 
evacuating the bowels. 3. Natural actions catenated with lunar 
periods. Menfruation. Venereal orgafn of animals. Barren- 
nefs. III. Periods of difeafed animal afiicns from fated returns 
of nocturnal cold, from folar and lunar influence. Periods of 
diurnal fever, hectic fever, quotidian, tertian, quartan fever. 
Periods of gout, pleurify, of fevers with arterial debility, and with 
arterial frength. Periods of rhaphania, of nervous cough, hemi- 
crania, arterial hemorrhages, hemorrhoids, hemoptoe, epilepfy, 
palfy, apoplexy, madnefs. IV. Critical days depend on lunar 
periods. Lunar periods in the fmall-pox. 
I. If any of our mufcles be made to contract violently by the 
power of volition, as thofe of the fingers, when any one hangs 
by his hands on a fwing, fatigue foon enfues; and the mufcles 
ceafe to aft owing to the temporary exhauftion of the fpirit of 
animation ; as foon as this is again accumulated in the mufcles, 
they are ready to contrafl again by the efforts of volition. 
Thofe violent mufcular actions induced by pain become in 
the fame manner intermitted and recurrent; as in labour-pains, 
vomiting, tenefmus, ftrangury ; owing likewife to the temporary 
exhauftion of the fpirit of animation, as above mentioned. 
When any ftimulus continues long to aft with unnatural vi- 
olence, fo as to produce too energetic aftion of any of our 
moving organs, thofe motions foon ceafe, though the ftimulus 
continues to aft; as in looking long on a bright objeft, as on an 
inch-fquare of red filk laid on white paper in the funfhine. See 
Plate I. in Seft. III. I. 
On the contrary, where lefs of the ftimulus of volition, fenfa- 
tion, or irritation, has been applied to a mufcle than ufual; 
there appears to be an accumulation of the fpirit of animation in 
the moving organ ; by which it is liable to aft with greater 
energy from lefs quantity of ftimulus, than was previoufly nec- 
efiary to excite it into fo great aftion ; as after having been im- 
merfed in fnow the cutaneous veflels of our hands are excited 
into Sect. XXXVI. 2. 1. 
OF DISEASES. 
353 
into ftronger action by the ftimulus of a lefs degree of heat, 
than would previoully have produced that effect. 
From hence the periods of fome fever-fits may take their ori- 
gin, either fimply, or by their accidental coincidence with lunar 
and folar periods, or with the diurnal periods of heat and cold, 
to be treated of below ; for during the cold fit at the commence- 
ment of a fever, from whatever caufe that cold fit may have 
been induced, it follows, i. That the fpirit of animation muft 
become accumulated in the parts, which exert during this cold 
fit lefs than their natural quantity of action. 2. If the caufe 
producing the cold fit does not increafe, or becomes diminifbed ; 
the parts before benumbed or inactive become now excitable by 
finaller ftimulus, and are thence thrown into more violent ac- 
tion than is natural ■, that is a hot fit fucceeds the cold one. 3. 
By the energetic action of the fyftem during the hot fit, if it 
continues long, an exhauftion of the fpirit of animation takes 
place ; and another cold fit is liable to fucceed, from the moving 
fyftem not being excitable into adtion from its ufual ftimulus. 
This inirritability of the fyftem from a too great previous ftimu- 
lus, and confequent exhauftion of fenforial power, is the caufe of 
the general debility, and ficknefs, and head-ach, fome hours af- 
ter intoxication. And hence we fee one of the caufes of the 
periods of fever-fits; which however are frequently combined 
with the periods of our diurnal habits, or of heat and cold, or of 
folar or lunar periods. 
When befides the tendency to quiefcence occafioned by the 
expenditure of fenforial power during the hot fit of fever, fome 
other caufe of torpor, as the folar or lunar periods, is necefiary 
to the introduction of a fecond cold fit; the fever becomes of 
the intermittent kind ; that is, there is a fpace of time intervenes 
between the end of the hot fit, and the commencement of the 
next cold one. But where no exterior caufe is nccefl'ary to the 
introduction of the fecond cold fit ; no fuch interval of health 
intervenes ; but the fecond cold fit commences, as foon as the 
fenforial power is fufficiently exhaufted by the hot fit ; and the 
fever becomes continual. 
II. 1. The following are natural animal actions, which are 
frequently catenated with our daily habits of life, as well as ex- 
cited by their natural irritations. The periods of hunger and 
third become catenated with certain portions of time, or degrees 
of exhauftion, or other diurnal habits of life. And if the pain 
of hunger be not relieved by taking food at the ufual time, it is 
liable to ceafe till the next period of time or other habits recur ; 
this is not only true in refpect to cur general defire of food, but 
the kinds of it alfo are governed by this periodical habit ; info- 
Vou I. X x much 354 
PERIODS 
Sect. XXXVI. 2. 2. 
much that beer taken to breakfaft will difturb the digeftion of 
thofe, who have been accuftomed to tea ; and tea taken at din- 
ner will difagree with thofe, who have been accuftomed to beer. 
Whence it happens, that thofe, who have weak ftomachs, will 
be able to digeft more food, if they take their meals at regular 
hours ; becaufe they have both the ftimulus of the aliment they 
take, and the periodical habit, to aflift their digeftion. 
The periods of emptying the bladder are not only dependent 
-on the acrimony or diftention of the water in it, but are fre- 
quently catenated with external cold applied to the Ikin, as in 
cold bathing, or wafhing the hands ; or with other habits of 
life, as many are accuftomed to empty the bladder before going 
to bed, or into the houfe after a journey, and this whether it be 
full or not. 
Our times of refpiration are not only governed by the ftimu- 
lus of the blood in the lungs, or our defire of frefh air, but alfo 
by our attention to the hourly objects before us. Hence when 
a perfon is earneftly contemplating an idea of grief, he forgets to 
breathe, till the fenfation in his lungs becomes very urgent ; 
and then a figh fucceeds for the purpofe of more forcibly pufti- 
ing forwards the blood, which is accumulated in the lungs. 
Our times of refpiration are alfo frequently governed in part 
by our want of a fteady fupport for the actions of our arms, 
and hands, as in threading a needle, or hewing wood, or in 
fwimming ; when we are intent upon thefe objects, we breathe 
at the intervals of the exertion of the pectoral mufcles. 
2. The following natural animal actions are influenced by fo- 
lar periods. The periods of fleep and of waking depend much 
on the folar period, for we are inclined to fleep at a certain hour, 
and to awake at a certain hour, whether we have had more or 
lefs fatigue during the day, if within certain limits ; and are li- 
able to wake at a certain hour, whether we went to bed earlier 
or later, within certain limits. Hence it appears, that thofe who 
complain of want of fleep, will be liable to fleep better or longer, 
if they accuftom themfelves to go to reft, and to rife at certain 
hours. 
The periods of evacuating the bowels are generally connected 
with fome part of the folar day, as well as with the acrimony or 
diftention occafioned by the feces. Hence one method of cor- 
recting coftivenefs is by endeavouring to eftablifh a habit of 
evacuation at a certain hour of the day, as recommended by Mr. 
Locke, which maybe accomplifhcd by ufing daily voluntary ef- 
forts at thofe times, joined with the ufual ftimulus of the mate- 
rial to be evacuated. 
3. The following natural animal aCtions are connected with 
lunar Sect. XXXVI. 3. 1. 
OF DISEASES. 
355 
lunar periods, i. The periods of female menftruation are con- 
nected with lunar periods to great exactnefs, in fome inftances 
even to a few hours. Thefe do not commence or terminate at 
the full or change, or at any other particular part of the luna- 
tion, but after they have commenced at any part of it, they con- 
tinue to recur at that part with great regularity, unlefs difturbed 
by fome violent circumftance, as explained in Sect. XXXII. No. 
6. their return is immediately caufed by deficient venous ab- 
forption, which is owing to the want of the ftimulus, defigned 
by nature, of amatorial copulation, or of the growing fetus. 
When the catamenia returns fooner than the period of lunation, 
it (hews a tendency of the constitution to irritability ; that is to 
debility, or deficiency of fenforial power, and is to be relieved 
by fmall dofes of fteel and opium. 
The venereal orgafm of birds and quadrupeds feems to com- 
mence, or return about the moll powerful lunations at the vernal 
or autumnal equinoxes ; but if it be difappointed of its objeCt, 
it is faid to recur at monthly periods ; in this refpeCt refembling 
the female catamenia. Whence it is believed, that women are 
more liable to become pregnant at or about the time of their cat- 
amenia, than at the intermediate times ; and on this account 
they are feldom much miftaken in their reckoning of nine lunar 
periods from the laft menftruation; the inattention to this may 
fometimes have been the caufe of fuppofed barrennefs, and is 
therefore worth the obfervation of thofe, who wifli to have 
children. 
III. We now come to the periods of difeafed animal actions. 
The periods of fever-fits, which depend on the ftated returns of 
nocturnal cold, are difcufled in SeCl. XXXII. 3. Thofe which 
originate or recur at folar or lunar periods, are alfo explained in 
Section XXXII. 6. Thefe we (hall'here enumerate; obferv- 
ing, however, that it is not more furprifing, that the influence of 
the varying attractions of the fun and moon, fhould raife the 
ocean into mountains, than that it fhould affeCt the nice fenfi- 
bilities of animal bodies ; though the manner of its operation on 
them is difficult to be underftood. It is probable however, that 
as this influence gradually leflens during the courfe of the day, 
or of the lunation, or of the year, fome actions of our fyftem be- 
come lefs and lefs ; till at length a total quiefcence of fome part 
is induced ; which is the commencement of the paroxyfms of 
fever, of menftruation, of pain with dccreafed aCtion of the af- 
fected organ, and of consequent convulfion. 
1. A diurnal fever in fome weak people is diftinCtly obferved 
to come on towards evening, and to ceafe with a moift ikin early 
in the morning, obeying the folar periods. Perfons of weak 
conftitutions 356 
PERIODS 
Sect. XXXVI. 3. 2. 
conftitutions are liable to get into better fpirits at the accefs of 
the hot fit of this evening fever; and are thence inclined to fit 
up late ; which by further enfeebling them increa.es the dif- 
eafe ; whenCe they lofe their ftrength and their colour. 
Hence delicate ladies, who do not ufe rouge, are obferved to 
become paler in the evening; which is probably owing to the 
circulation through the whole fyftem being lefs frequently per- 
formed in a given time, though the pulfe is quicker ; and hence 
the mafs of blood becomes lefs frequently oxygenated in the 
lungs, and in confequence has a lefs florid colour. This pale 
colour therefore arifes from debility, which occurs to delicate 
people in the evening from the exliauftion of fenforial power 
during the day, and is generally attended by quicknefs of pulfe ; 
by which circumftance the debility may in fome degree be 
meafured. 
Another caufe of the colour of the fk'n may occafionally de- 
pend on the increafed aClion of the cutaneous capillaries, as in 
the hot fit of fever; or by the production of new blood veflels, 
as in topical inflammations. And palenefs may arife from the 
contrary fituations, as from inaction of the cutaneous capillaries 
in the cold paroxyfm of fever, and from the concretion ol the 
fides of the fmall cutaneous arteries, as in old age. 
2. The periods of heCtic fever, fuppofed to arife from ab- 
forption of matter, obey the diurnal periods like the above, 
having the exacerbefcence towards evening, and the remif- 
fion early in the morning, with fweats, or diarrhoea, or urine 
with white fediment. 
3. The periods of quotidian fever are either catenated with 
folar time, and return at the intervals of twenty-four hours ; or 
with lunar time, recurring at the intervals of about twenty-five 
hours. There is great ufe in knowing with what circumftances 
the periodical return or newr morbid motions are conjoined, *as 
the mofl effectual times of exhibiting the proper medicines arc 
thus determined. So if the torpor, which ufhers in an ague fit, 
is catenated with the lunar day; it is known when the bark or 
opium muft be given, fo as to exert its principal efleCt about the 
time of the expeCled return. Solid opium fhould be given about 
an hour before the expeCled cold fit ; liquid opium and wine 
about half an hour ; the bark repeatedly for fix or eight hours 
previous to the expeCled return. 
4. The periods of tertian fevers, reckoned from the com- 
mencement of one cold fit to the commencement of the next 
cold fit, recur with folar intervals oi forty-eight hours, or with 
lunar ones of about fifty hours. When the recurrence of thefe 
begins one or tu^o hours earlier than the folar period, it Ihews, 
that Sect. XXXVI. 3. 5. 
OF DISEASES. 
357 
that the torpor or cold fit is produced by lefs external influence ; 
and therefore that it is more liable to degenerate into a fever 
with only remiflions ; fo when menftruation recurs fooner than 
the period of lunation, it fliews a tendency of the habit to tor- 
por or in irritability. 
5. 'rhe periods of quartan fevers return at folar intervals of 
feventy-two hours, or at lunar ones of about feventy-four hours 
•and a half. This kind of ague appears moft in moift cold au- 
tumns, and in cold countries replete with marfhcs. It is at- 
tended with greater debility, and its cold aecefs more difficult 
to prevent. For where there is previoufly a deficiency of fenfo- 
rial power the conilitution is liable to run into greater torpor 
from any further diminution of it; two ounces of bark and feme 
fteel fhould be given on the day before the return of the cold 
paroxyfm, and a pint of wine by degrees a few hours before its 
return, and thirty drops of laudanum one hour before the ex- 
pefted cold fit. 
6. The periods of the gout generally commence about an 
hour before fun-rife, which is ufually the coldeft part of the 
twenty-four hours. The greater periods of the gout feem allo 
to obferve the folar influence, returning about the fame feafon 
of the year. 
7. The periods of the pleurify recur with exacerbation of the 
pain and fever about fun-fet, at which time venefetdion is of molt 
fervice. The fame may be obferved of the inflammatory rheu- 
matifm, and other fevers with arttrial firength, which feem to 
obey folar periods ; and thofe with debility feem to obey lunar 
ones. 
8. The periods of fevers with arterial debility feem to obey 
the lunar day, having their accefs daily nearly an hour later ; 
and have fometimes two accedes in a day, refembling the lunar 
effects upon the tides. 
9. The periods of rhaphania, or convulfions of the limbs from 
rheumatic pain, feem to be connected with folar influence, re- 
turning at nearly the fame hour for weeks together, unlefs dif- 
turbed by the exhibition of powerful dofes of opium. 
So the periods of tuflis ferina, or violent cough with flow 
pulfe, called nervous cough, recur by folar periods. Five grains 
of opium given at the time the cough commenced dillurbed the 
period, from feven in the evening to eleven, at which time it 
regularly returned for fome days, during which time the opium 
was gradually omitted. Then 120 drops of laudanum were 
givenan hour before theaccefs of the cough, and it totally ceafed. 
The laudanum was continued a fortnight, and then gradually 
difeontinued. 
10. The 358 
PERIODS 
Sect. XXXVI. 3. 10. 
io. The periods of hemicrania, and of painful epilepfy, are 
liable to obey lunar periods, both in their diurnal returns, and 
in their greater periods of weeks, but are allo induced by other 
exciting caufes. 
11. The periods of arterial haemorrhages feem to return at 
folar periods about the fame hour of the evening or morning. 
Perhaps the venous haemorrhages obey the lunar periods, as the 
catamenia, and haemorrhoids. 
12. The periods of the haemorrhoids, or piles, in fome recur 
monthly, in others only at the greater lunar influence about the 
equinoxes. 
13. The periods of haemoptoc fometimes obey folar influence, 
recurring early in the morning for leveral days ; and fometimes 
lunar periods, recurring monthly; and fometimes depend on 
our hours of fleep. See Clafs I. 2. 1. 9. 
14. Many of the firft periods of epileptic fits obey the month- 
ly lunation with fome degree of accuracy ; others recur only at 
the moft powerful lunations before the vernal equinox, and after 
the autumnal one ; but when the conftitution has gained a 
habit of relieving difagreeable fenfations by this kind of exertion, 
the fit recurs from any flight caufe. 
15. The attack of palfy and apoplexy are known to recur with 
great frequency about the equinoxes. 
16. There are numerous inftances of the effedt of the luna- 
tions upon the periods of infanity, whence the name of lunatic 
has been given to thofe afflicted with this difeafe. 
IV. The critical days, in which fevers are fuppofed to termi- 
nate, have employed the attention of medical philofophers from 
the days of Hippocrates to the prefent time. In whatever part 
of a lunation a fever commences, which owes either its whole 
caufe to folar and lunar influence, or to this in conjunction with 
other caufes ; it would feem, that the effect would be the great- 
eft at the full and new moon, as the tides rife highelt at thofe 
times, and would be the leaft at the quadratures; thus if a fe- 
ver-fit fhould commence at the new or full moon, occafioned 
by the folar and lunar attraction diminilhing fome chemical af- 
finity of the particles of blood, and thence decreafing their ftimu- 
lus on our fanguiferous fyltem, as mentioned in Sect. XXXII. 
6. this eftedt will daily decreafe for the firlt feven days, and 
will then increafe till about the fourteenth day, and will again 
decreafe till about the twenty-firll day, and increafe again till 
the end of the lunation. If a fever-fit from the above caufe 
ihould commence on the feventh day after either lunation, the 
reverie of the above circumftances would happen. Now it is 
probable, that thofe fevers, whofe crifis or terminations are in- 
fluenced Sect. XXXVI. 4. 1. 
OF DISEASES. 
359 
fluenced by lunations, may begin at one or other of the above 
times, namely at the changes or quadratures ; though fufficient 
obfervations have not been made to afcertain this circumftance. 
Hence I conclude, that the fmall-pox and mealies have their 
critical days, not governed by the times required for certain 
chemical changes in the blood, which afTedt or alter the ftimu- 
lus of the contagious matter, but from the daily increafing or 
decreafmg effect of this lunar link of catenation, as explained in 
Section XVII. 3.3. And as other fevers terminate moll fre- 
quently about the feventh, fourteenth, twenty-firft, or about the 
end of four weeks, when no medical afliftance has difturbed 
their periods, I conclude, that thefe crifes, or terminations, are 
governed by periods of the lunations, though we are ftill igno- 
rant of their manner of operation. 
In the diftinft fmall-pox the veftiges of lunation are very ap- 
parent ; after inoculation a quarter of a lunation precedes the 
commencement of the fever, another quarter terminates with 
the complete eruption, another quarter with the complete matu- 
ration, and another quarter terminates the complete abforption. 
of a material now rendered inoffenfive to the conftitution. 
SECT. 360 
DIGESTION, 
Sect. XXXVII. i. 
SECT. XXXVII. 
OF DIGESTION, SECRETION, NUTRITION, 
I. Cryflals increafe by the greater attraction of their fides. Accre- 
tion by chemical precipitations, by welding, by preffure, by aggluti- 
nation. II. Hunger, digef ion, why it cannot be imitated out of 
the body. LaCleals abforb by animal [election, or appetency. III. 
The glands and pores abforb nutritious particles by animalfeleCtion. 
Organic particles of Buffon. Nutrition applied at the time of 
elongation of fibres. Like inflammation. IV. It feems eafier to 
have preferved animals than to reproduce them. Old age and death 
from inirritability. Three caufes of this. Original fibres of the 
organs offenfe and mufcles unchanged. V. Art of producing 
long life. 
I. The larger cryftals of faline bodies may be conceived to 
arife from rhe combination of fmaller cryftals of the fame form, 
owing to the greater attractions of their fides than of their an- 
gles. Thus if eight cubes were floating in a fluid, whofe fric- 
tion or refiftance is nothing, it is certain the fides of thefe cubes 
would attract each other ftronger than their angles ; and hence 
that thefe eight fmaller cubes would fo arrange themfelves as to 
produce one larger one. 
There are other means of chemical accretion, fuch as the de- 
pofitionsof dilTolved calcareous or fiiiceous particles, as are fe^n 
in the formation of the ftalaclites of limeftone in Derby (hire, or 
ofcalcedone in Cornwall. Other means of adhefion are produ- 
ced by heat and prefl'ure, as in the welding of iron-bars ; and 
other means by Ample prefl'ure, as in forcing two pieces of ca- 
outchou, or elaftic gum, to adhere; and laftly, by the aggluti- 
nation of a third fubftance penetrating the pores of the other 
two, as in the agglutination of wood by means of animal gluten. 
Though the ultimate particles of animal bodies are held togeth- 
er during life, as well as after death, by their fpecific attraction 
of cohelion, like all other matter ; yet it does not appear, that 
their original organization was produced by chemical laws, and 
their production and increafe mull therefore only be looked for 
from the laws of animation. 
II. When the pain of hunger requires relief, certain parts of 
the material world, which furround us, when applied to our 
palates, excite into action the mufcles of deglutition ; and the 
material is fwallowed into the ftomach. Here the new aliment 
becomes mixed with certain animal fluids, and undergoes a 
chemical Sect. XXXVII. 3. 1. 
SECRETION, &c. 
361 
chemical procefs, termed digeftion ; which, however, chemiftry 
has not yet learnt to imitate out of the bodies of living animals 
or vegetables. This procefs feems very fimilar to the faccharine 
procefs in the lobes of farinaceous feeds, as of barley, when it 
begins to germinate ; except that, along with the fugar, oil and 
mucilage are alfo produced j which form the chyle of ani- 
mals, which is very fimilar to their milk. 
The reafon, 1 imagine, why this chyle-making, or faccharine 
procefs, has not yet been imitated by chemical operations, is 
owing to the materials being in fuch a fituation in refpect to 
warmth, moillure, and motion ; that they will immediately 
change into the vinous or acetous fermentation ; except the 
new fugar be abforbed by the numerous lacteal or lymphatic 
veflels, as focn as it is produced ; which is not eafy to imitate 
in the laboratory. 
Thefe ladle al veflels have mouths, which are irritated into ac- 
tion by the ftimulus of the fluid which furrounds them ; and by 
animal feledtion, or appetency, they abforb fuch part of the flu- 
id as is agreeable to their palate ; thofe parts, for instance, 
which are already converted into chyle, before they have time 
to undergo another change by a vinous or acetous fermentation. 
This animal abforption of fluid is almoft vifible to the naked eye 
in the adlion of the pun cl a lachrymalia ; which imbibe the tears 
from the eye, and discharge them again into the noftrils. 
III. The arteries conftitute another refervoir of a changeful 
fluid ; from which, after its recent oxygenation in the lungs, a 
further animal feledlion of various fluids is abforbed by the nu- 
merous glands ; thefe feledt their refpedlive fluids from the 
blood, which is perpetually undergoing a chemical change but 
the feleclion by thefe glands, like that of the ladleals, which 
open their mouths into the digeiting aliment in the ftomach, is 
from animal appetency, not from chemical affinity ; fecretion 
cannot therefore be imitated in the laboratory, as it confiils in a 
feleclion of part of a fluid during the chemical change of that 
fluid. 
The mouths of the ladleals, and lymphatics, and the ultimate 
terminations of the glands, are finer than can eafily be conceived ; 
yet it is probable, that the pores, or interftices of the parts, or 
coats, which conftitute thefe ultimate veflels, may ftill have 
greater tenuity j and that thefe pores from the above analogy 
muft poflefs a fimilar power of irritability, and abforb by their 
living energy the particles of fluid adapted to their purpofes, 
whether to replace the parts abraded or diflblved, or to elongate 
and enlarge themfelves. Not only every kind of gland is thus 
endued with its peculiar appetency, and feledls the material 
Vol. I. Y y agreeable 362 
DIGESTION, 
Sect. XXXVII. 3. r. 
Agreeable to its tafte from the blood, but every individual pore 
acquires by animal fele&ion the material, which it wants ; and 
thus nutrition feems to be performed in a manner fo fimilar to 
fecretion ; that they only differ in the one retaining, and the 
other parting again with the particles, which they have ielected 
from the blood. 
They may, indeed, differ in another circumftance ; that in 
nutrition certain particles of the circulating blood, which have 
not previoufly been ufed in the fyftem, are embraced, and form 
a folid part of the animal. Whereas in fome of the fecretions, 
thofe particles appear to be imbibed by the glands, which have 
already been ufed in the fyftem, and probably abraded or de- 
tached from it into the circulation : thefe are depofited in refer- 
voirs for future ufe, as bile and mucus ; or excluded for other 
purpofes, as femen and tears; or evacuated fimply as feces and 
urine. And it fhould be obferved, that all thefe fecretions are 
produced from their glands, in a very dilute ftate, mingled, I be- 
lieve, with mucus diffolved in water; which is in part re-ab- 
forbed from the refervoirs of the glands, or from the cells or 
furfaces of the body, that no unneceffary wafte of animal mat- 
ter may occur ; which accounts for the urinary bladders of fifh, 
which would otherwife appear to be unneceffary, according to 
the obfervation of Munro. 
This way of accounting for nutrition from ftimulus, and the 
confequent animal fele&ion of particles, is much more analo- 
gous to other phenomena of the animal microcofm, than by 
having recourfe to the microfcopic animalcula, or organic par- 
ticles of Buffon and Needham ; which being already compound- 
ed muft themfelves require nutritive particles to continue their 
own exiftence. And muft be liable to undergo a change by our di- 
geftive or fecretory organs; otherwife mankind would loon refem- 
ble by their theory the animals, which they feed upon. He, who 
is nourifhed by beef or venifon, would in time become horned ; 
and he, who feeds on pork or bacon, would gain a nofe proper 
for rooting into the earth, as well as for the perception of odours. 
The whole animal fyftem may be confidered as confifting of 
the extremities of the nerves, or of having been produced from 
them ; if we except perhaps the medullary part of the brain 
refiding in the head and fpine, and in the trunks of the nerves. 
Thefe extremities of the nerves are either of thofe of locomotion, 
which are termed mufcular fibres; or of thofe of fenfation, 
which conftitute the immediate organs of fenfe, and which have 
alfo their peculiar motions. Now as the fibres, which confti- 
tute the bones and membranes, poflefTed originally fenfation and 
motion; and are liable again topofiefs them, when they become 
inflamed ; Sect. XXXVII. 3.1. 
SECRETION, &c. 
363 
inflamed; it follows, that thofe were, when fir ft formed, ap- 
pendages to the nerves of fenfation or locomotion, or were 
formed from them. And that hence all thefe folid parts of the 
body, as they have originally confided of extremities of nerves, 
require an appofition of nutritive particles of a fimilar kind, 
contrary to the opinion of Buffon and Needham above recited. 
JLaftly, as all thefe filaments have poffeffed, or do poffefs, the 
power of contraction, and of confequent inertion or elongation ; 
it feems probable, that the nutritive particles are applied during 
their times of elongation ; when their original conftituent par- 
ticles are removed to a greater diftance from each other. For 
each mufcular or fenfual fibre may be confidered as a row or 
firing of beads ; which approach, when in contraCtion, and re- 
cede during its reft or elongation ; and our daily experience 
ihews us, that great aCtion emaciates the fyftem, and i.hat.it.js. 
repaired during reft. 
Something like .this is feen out of the body; for if a hair, or 
a fingle untwifted fibre of flax or filk, be foaked in water ; it be- 
comes longer and thicker by the water, which is abforbed into 
its pores. Now if a hair.could be fuppofed to be thus immerfed 
in a folution of particles fimilar to thofe, which compofe it 5 
one may imagine, that it might be thus increafed in weight and 
magnitude; as the particles of oak-bark increafe the fubftance 
of the hides of beafts in the procefs of making leather. I men- 
t;on thefe not as philofophic analogies, but as fimilies to facili- 
tate our ideas, how an accretion of parts may be efteCted by 
animal appetences, or fele&ions, in a manner fomewhat fimilar 
to mechanical or chemical attractions. 
If thofe new particles of matter, pxevioufly prepared by di- 
geftion and fanguification, only fupply the places of thofe, which 
have been abraded by the aCtions of the fyftem, it is properlv 
termed nutrition. If they are applied to the extremities of the 
nervous fibrils, or in fuch quantity as to increafe rhe length or 
craflitude of them, the body becomes at the fame time enlarged, 
and its growth is increafed, as well as its deficiencies repaired. 
In this laft cafe fomething more than a fimple appofition or 
feleCtion of particles feems to be neceffary ; as many parts of 
the fyftem during its growth are caufed to recede from thofe, 
with which they were before in contact; as the ends of the 
bones, or cartilages, recede from each other, as their growth 
advances: this procefs refembles inflammation, as appears in 
ophthalmy, or in the production of new fleih in ulcers, where 
pid veffels are enlarged, and new ones produced ; and like that 
is attended' with fenfation. In this fituation the veflels become 
4iftended with blood, and acquire greater fenfibility, and may 
th us 364 
DIGESTION, 
Sect. XXXVII. 4.f; 
thus be compared to the creation of the penis, or of the nipples 
of the breafts of women ; while new particles become added at 
the fame time ; as in the procefs of nutrition above defcribed. 
When only the natural growth of the various parts of the 
body is produced, a pleafurable fenfation attends it, as in youth, 
and perhaps in thofe, who are in the progrefs of becoming fat. 
When an unnatural growth is the confequence, as in inflam- 
matory difeafes, a painful fenfation attends the enlargement of 
the fyftem. 
IV. This appofition of new parts, as the old ones difappear, 
fele<Sled from the aliment we take, firft enlarges and ftrength- 
ens our bodies for twenty years; for another twenty years it 
keeps us in health and vigour, and adds ftrength andfolidity to 
the fyftem, and then gradually ceafes to nourilh us properly; 
an^kfor -another twenty years we gradually fink into decay, and 
finally ceafe to act, and to exift. 
On confidering this fubjeft one (hould have imagined at firft 
view, that it might have been eafier for nature to have fup- 
ported her progeny for ever in health and life, than to have per- 
petually reproduced them by the wonderful and myfterious 
procefs of generation. But it feems our bodies by Jong habit 
ceafe to obey the ftimulus of the aliment, which fhould fupport 
us. After we have acquired our height and folidity we make 
no more new parts, and the fyftem obeys the irritations, fen- 
fations, volitions, and aflbciations, with lefs and lefs energy, till 
the whole finks into inaftion. 
Three caufes may confpire to render our nerves lets excitable, 
which have been already mentioned, i. If a ftimulus be greater 
than natural, it produces too great an exertion of the ftimulated 
organ, and in confequence exhaufts the fpirit of animation ; and 
the moving organ ceafes to a6l, even though the ftimulus be 
continued. And though reft will recruit this exhauftion, yet 
fome degree of permanent injury remains, as is evident after ex- 
pofing the eyes long to too ftrong a light. 2. If excitations 
weaker than natural be applied, fo as not to excite the organ 
into action, (as when finall dofes of aloes or rhubarb are ex- 
hibited,) they may be gradually increafed, without exciting the 
organ into action ; which will thus acquire a habit of difobedi- 
ence to the ftimulus ; thus by increasing the dofe by degrees, 
great quantities of opium or wine may be taken without intoxi- 
cation. See Se<ft. XII. 3. 1. 
3. Another mode, by which life is gradually undermined, is 
when irritative motions continue to be produced in confequence 
of ftimulus, but are not fucceeded by fen fation ; hence the 
ftimulus of contagious matter is not capable of producing fever 
3 Sect. XXXVII. 5. 1. 
SECRETION, &«. 
365 
a fecond time, beeaufe it is not fucceeded by fenfation. See 
Sert. XII. 3. 6. And hence, owing to the want of the gener- 
al pleafurable fenfation, which ought to attend digeftion and 
glandular fecretion, an irkfomenefs of life enfues ; and, where 
this is in greater excefs, the melancholy of old age occurs, with 
torpor or debility. 
From hence I conclude, that it is probable that the fibrillae, 
or moving filaments at the extremities of the nerves of fenfe, and 
the fibres which conftitute the mufcles (which are perhaps the 
only parts of the fyltem that are endued with contractile life) 
are not changed, as we advance in years, like the other parts of 
the body ; but only enlarged or elongated with our growth ; 
and in confequence they become lefs and lefs excitable into ac- 
tion. Whence, inftcad of gradually changing the old animal, 
the generation of a totally new one becomes necefiary with un- 
diminilhed excitability ; which many years will continue to ac- 
quire new parts, or new folidity, and then lofing its excitability 
in time, perifh like its parent. 
V. From this idea the art of preferving long health and life 
maybe deduced; which mull confift in ufing no greater ftimu- 
lus, whether of the quantity or kind of our food and drink, or 
of external circumftances, fuch as heat, and exercife, and wake- 
fulnefs, than is fufficient to preferve us in vigour ; and gradual- 
ly, as we grow old to increafe the llimulus of our aliment, as 
the inirritability of our fyftem increafes. 
The debilitating effects afcribed by the poet Martial to the 
excefiive ufe of warm bathing in Italy, may with equal propriety 
be applied to the warm rooms of England ; which, with the 
general excefiive ftimulus of fpirituous or fermented liquors, 
and in fome inftances of immoderate venery, contribute t» 
fhorten our lives. 
Balnea, vina, Venus, corrumpunt corpora nojlra: 
At faciunt vitam balnea, njina, Venus ! 
Wine, women, warmth, againft our lives combine; 
But what is life, without warmth, women, wine! 
SECT. 366 
OXYGENATION 
Sect. XXXVIIT. i. rJ 
SECT. XXXVIII. 
•F THE OXYGENATION OF THE BLOOD IN THE LUNGS, AND 
IN THE PLACENTA. 
I- Bloodabforbs oxygene from the air, whencephofphoric acid, change} 
its colour, gives out heat, and fome phlogiftic material, and acquires 
an ethereal fpirit, which is dffipated in fibrous motion. II. The 
placenta is a pulmonary organ like the gills of fifth. Oxygenation of 
the blood from air, from water, by lungs, by gills, by the placenta ; 
necejflty of this oxygenation to quadrupeds, to fifth, to the fetus in 
utero. Placental veffels inferted into the arteries of the mother. 
Ufe of cotyledons in cows. Why quadrupeds have not fanguifer- 
ous lochia. Oxygenation of the chick in the egg, of feeds. III. 
The liquor amnii is not excrementitious. It is nutritious. It is 
found in the efophagus and ftomach, and forms the meconium. 
Monftrous births without heads, eft ion of Dr. Harvey. 
I. From the recent difcoveries of many ingenious philofo* 
phers it appears, that during refpiration the blood imbibes the 
vital part of the air, called oxygene, through the membranes of 
the lungs ; and that hence refpiration may be aptly compared to 
a flow combuftion. As in combuftion the oxygene of the at- 
mofphere unites with fome phlogiftic or inflammable body, and 
forms an acid (as in the production of vitriolic acid from fulphur, 
or carbonic acid from charcoal, giving out at the fame time a 
quantity of the matter of heat; fo in refpiration the oxygene of 
the air unites with the phlogiftic part of the blood, and proba- 
bly produces phofphoric or animal acid, changing the colour of 
the blood from a dark to a bright red ; and probably fome of the 
matter of heat is at the fame time given out according to the 
theory of Dr. Crawford. But as the evolution of heat attends 
almoft all chemical combinations, it is probable, that it alfo at- 
tends the fecretions of the various fluids from the blood ; and 
that the conftant combinations or productions of new fluids by 
means of the glands conftitute the more general fource of ani- 
mal heat; this feems evinced by the univerfal evolution of the 
matter of heat in the blufh of ihame or of anger ; in which at 
the fame time an increafed fecretion of the perfpirable matter 
occurs ; and the partial evolution of it from topical inflamma- 
tions, as in gout or rhcumatifm, in which there is a fecretion of 
new blood-vefiels. 
Some medical philofophers have afcribed the heat of animal 
bodies to the iriCtion of the particles of the blood againft the 
fides S£ct. XXXVIII. 2. 1. 
OF BLOOD. 
367 
Iides of the veflels. But no perceptible heat has ever been pro- 
duced by the agitation of water, or oil, or quickfilver, or other 
fluids; except thofe fluids have undergone at the fame time fome 
chemical change, as in agitating milk or wine, till they become 
four. 
Befides the fuppofed production of phofphoric acid, and 
change of colour of the blood, and the production of carbonic 
acid, there would appear to be fomething of a more fubtile na- 
ture perpetually acquired from the atmofphere ; which is too 
fine to be long contained in animal veflels, and therefore re- 
quires perpetual renovation ; and without which perfeCt life 
cannot continue longer than a minute or two ; this ethereal flu- 
id is probably fecreted from the blood by the brain, and perpetu- 
ally diflipated in the aCtions of the mufcles and organs of fenfe, 
but which neverthelefs may remain for a longer time, where 
there is little or no exertion of the animal fibres, as in fyncope, 
and in thofe infeCts and other animals, which remain during the 
winter in a torpid ftate, and may not entirely evaporate from 
defeCl of warmth, or moifture, or other circumftances, as fnails 
are faid to have revived after having been many years in a dry 
cabinet, and flies after having been many months drowned in 
wine, and other infeCts after having been frozen. 
That the blood acquires fomething from the air, which is im- 
mediately neceifary to life, appears from an experiment of Dr. 
Hare, (Philof. TranfaCt. abridged, Vol. III. p. 239.) who 
found, " that birds, mice, &c. would live as long again in a 
veflel, where he had crowded in double the quantity of air by a 
condenfing engine, than they did when confined in air of the 
common denfity." Whereas if fome kind of deleterious vapour 
only was exhaled from the blood in refpiration ; the air, when 
condenfed into half its compafs, could not be fuppofed to receive 
fo much of it. 
II. Sir Edward Hulfe, a phyfician of reputation at the begin- 
ning of the prefent century, was of opinion, that the placenta 
was a refpiratory organ, like the gills of fifh ; and not an organ 
to iupply nutriment to the foetus; as mentioned in Derham's 
Phyfico-theology. Many other phyficians feem to have efpoufed 
the fame opinion, as noticed by Haller. Elem. Phyfiologiie, T. 
I. Dr. Gipfon publifhed a defence of this theory in the Medi- 
cal Eflays of Edinburgh, Vol. I. and II. which doCtrine is 
there controverted at large by the late Alexander Monro ; and 
iince that time the general opinion has been, that the placenta 
is an organ of nutrition only, owing perhaps rather to the au- 
thority of fo great a name, than to the validity of the arguments 
adduced in its fupport. The fubjcCt has lately been relumed by 
Dr. 368 
OXYGENATION 
Sect. XXXVI1L 2. i. 
Dr. James Jeffray, and by Dr. Forefter French, in their inaugu- 
ral diflertations at Edinburgh and at Cambridge ; who have de-, 
fended the contrary opinion in an able and ingenious manner ; 
and from whofe Thefes I have extracted many of the following 
remarks. 
Firft, by the late difeoveries of Dr. Prieftley, M. Lavoifier, 
and other philofophers, it appears, that the bafis of atmofpher- 
ical air, called oxygene, is received by the blood through the 
membranes of the lungs; and that by this addition the colour 
of the blood is changed from a dark to a light red. Secondly, 
that water poflefles oxygene alio as a part of its compofition, 
and contains air likewife in its pores ; whence the blood of fifh 
receives oxygene from the water, or from the air it contains, by 
means of their gills, in the fame manner as the blood is oxygena- 
ted in the lungs of air-breathing animals; it changes its colour 
at the fame time from a dark to a light red in the veflels of their 
gills, which conilitute a pulmonary organ adapted to the medi- 
um in which they live. Thirdly, that the placenta confifts of 
arteries carrying the blood to its extremities, and a vein bringing 
it back, refembling exactly in Itrudlure the lungs and gills above 
mentioned ; and that the blood changes its colour from a dark 
to a light red in palling through thefe veflels. 
This analogy between the lungs and gills of animals, and the 
placenta of the fetus, extends through a great variety of other 
circumftances; thus air-breathing creatures and fifh can live 
but a few minutes without air or water; or when they are con- 
fined in fuch air or water, as has been fpoiled by their own 
refpiration ; the fame happens to the fetus, which, as foon as 
the placenta is feparated from the uterus, muft either expand its 
lungs, and receive air, or die. Hence from the ftru&ure, as 
well as the ufe of the placenta, it appears to be a refpiratory or- 
gan, like the gills of filh, by which the blood in the fetus be- 
comes oxygenated. 
From the terminations of the placental veflels not being ob- 
ferved to bleed after being torn from the uterus, while thofe of 
the uterus effufe a great quantity of florid arterial blood, the 
terminations of the placental veflels would feem to be inferted 
into the arterial ones of the mother ; and to receive oxygenation 
from the palling currents of her blood through their coats or 
membranes ; which oxygenation is proved by the change of the 
colour of the blood from dark to light red in its paflage from 
the placental arteries to the placental vein. 
The curious Itrudture of the cavities or lacunas of the placen- 
ta, demonllrated by Mr. J. Hunter, explains this circumftance. 
That ingenious philofopher has Ihewn, that there are numerous 
cavities Sect. XXXVIII. 2. 1. 
OF BLOOD. 
369 
cavities or lacunae formed on that fide of the placenta, which is 
iti contact with the uterus ; thofe cavities or cells are filled with 
blood from the maternal arteries, which open into them ; which 
blood is again taken up by the maternal veins, and is thus per- 
petually changed. While the terminations of the placental ar- 
teries and veins are fpread in fine reticulation on the fides of 
thefe cells. Ami thus, as the growing fetus requires greater 
oxygenation, an apparatus is produced refembling exactly the 
air-cells of the lungs. 
In cows, and other ruminating animals, the internal furface 
of the uterus is unequal like hollow cups, which have been 
called cotyledons ; and into thefe cavities the prominences of 
the numerous placentas, with which the fetus of thofe animals 
is furnifhed, are inferted, and ftriflly adhere ; though they may 
be extracted without effufion of blood. Thefe inequalities of 
the uterus, and the numerous placentas in confequence, feem to 
be defigned for the purpofe of expanding a greater furface for 
the terminations of the placental vefiels for the purpof* or re- 
ceiving oxygenation from the uterine ones ; as the progeny of 
this clafs of animals are more completely formed before their 
nativity, than that of the carnivorous clafles, and mull thence in 
the latter weeks of pregnancy require greater oxygenation. 
Thus calves and lambs can walk about in a few minutes after 
their birth ; while puppies and kittens remain many days with- 
out opening their eyes. And though on the feparation of the 
cotyledons of ruminating animals no blood is eflufed, yet this is 
owing clearly to the greater power of contraftion of their ute- 
rine lacunae or alveoli. See Medical Eflays, Vol. V. page 144. 
And from the fame caufe they are not liable to a fanguiferous 
menftruation. 
The neceflity 6f the oxygenation of the blood in the fetus is 
farther illuftratcd bv the analogy of the chick in the egg ; which 
appears to have its blood oxygenated at the extremities of the 
veflels furrounding the yolk; which are fpread on the air-bag 
at the broad end of the egg, and may abforb oxygene through 
that moift membrane from the air confined behind it j and which 
is (hewn by experiments in the exhaufted receiver to be change- 
able through the (hell. See Phytologia, Se6t. III. 
This analogy may even be extended to the growing feeds of 
vegetables ; which were (hewn by Mr. Scheele to require a reno- 
vation of the air over the water, in which they wqre confined. 
Many vegetable feeds are furrounded with air in their pods or 
receptacles, as peas, the fruit of (taphylea, and lichnis veficaria ; 
but it is probable, that thofe feeds after they are filed, as well as 
the fpawn of fiflt. by the.fituation of the former on or near the 
Vol. I. Z 1. moift 370 
OXYGENATION 
Sect. XXXVIII. 3.1, 
moift and aerated furfacc of the earth, and of the latter in the 
ever-changing and ventilated water, may not be in need of an 
apparatus for the oxygenation of their firft blood, before the 
leaves of one, and the gills of the other, are produced for this 
purpofe. See Phytologia, Sect. III. 
III. i. There are many arguments, befides the ftrift analogy 
between the liquor amnii and the albumen ovi, which (hew the 
former to be a nutritive fluid; and that the fetus in the latter 
months of pregnancy takes it into its ftomach ; and that in con- 
fequence the placenta is produced for fome other important 
purpofe. 
Firft, that the liquor amnii is not an excrementitious fluid is 
evinced, becaufe it is found in greater quantity, when the fetus 
is young, decreafing after a certairf period till birth. Haller af- 
ferts, " that in forne animals but a fmall quantity of this fluid re- 
mains at the birth. In the eggs of hens it is confumed on the 
eighteenth day, fo that at the exclufion of the chick fcarcely any 
remains. In rabbits before birth there is none." Elem. Phyfiol. 
Had this been an excrementitious fluid, the contrary would 
probably have occurred. Secondly, the fkin of the fetus is cov- 
ered with a whitiih cruft or pellicle, which would feem to pre- 
clude any idea of the liquor amnii being produced by any exfu- 
dation of perfpixable matter. And it cannot confift of urine, 
becaufe in brute animals the urachus pafles from the bladder to 
the alantois for the exprefs purpofe of carrying off that fluid ; 
which however in the human fetus feems to be retained in the 
diftended bladder, as the feces are accumulated in the bowels of 
all animals. 
2. The nutritious quality of the liquid, which furrounds the 
fetus, appears from the following confiderations. i. It is co- 
agulable by heat, by nitrous acid, and by fpirit of wine, like 
milk, ferum of blood, and other fluids, which daily experience 
evinces to be nutritious. 2. It has a faltilh tafte according to 
the accurate Baron Haller, not unlike the whey of milk, which 
it even refembles in fmell. 3. The white of the egg which 
conftitutes the food of the chick, is fhewn to be nutritious by 
our daily experience ; befides the experiment of its nutritious 
effects mentioned by Dr. Fordyce in his late Treatife on Di- 
geftion, p. 178 j who add«, that it much refembles the effcntial 
parts of the ferum of blood. 
3. A fluid fimilar to the fluid, with which the fetus is fur- 
rounded, e.^ept what little change may be produced by a begin- 
ning digeftion, is found in the fame manner in the ftomach of 
the chick. 
Numerous hairs, fimilar to thofe of its fkin, are perpetually 
. ■ found. Sect. XXXVIII.'3. 3. 
OF BLOOD. 
371 
found among the contents of the ftomach in new-born calves ; 
which mult therefore have licked themfelves before their nativi- 
ty. Blafii Anatom. See Seft. XVI. 2. on Inftimft. 
The chick in the egg is feen gently to move in its furround- 
ing fluid, and to open and (hut its mouth alternately. The 
fame has been observed in puppies. Haller's El. Phyf. I. 8. 
p. 201. 
A column of ice has been feen to reach down the cefophagus 
from the mouth to the ftomach in a frozen fetus ; and this ice 
was the liquor amnii frozen. 
The meconium, or firft feces, in the bowels of new-born in- 
fants evince, that fomething has been digefted.; and what could 
this be but the liquor amnii together with the recrements of the 
gaftric juice and gall, which were neceflary for its digeftion ? 
Another argument to evince, that the fetus is nourifhed by ali- 
ment taken into the ftomach and inteftines by the mouth during 
the latter months of pregnancy, may be deduced from the liver 
of the fetus ; which Haller obferves to be very large ; not like 
the lungs, as if defigned for the future man after nativity. Phy- 
fiol. Vol. VI. p. 6 j 8. Whence a fecretion of bile muft al- 
ready exift, which can ferve no purpofe but to be mixed with 
the digefting aliment. 
There have been recorded feme monftrous births of animals 
without heads, and confequently without mouths, which feem 
to have been delivered on doubtful authority, or from inaccurate 
obfervation. There are two of fuch monftrous productions 
however better attefted ; one of a human fetus, mentioned by 
Gipfon in tire Scots Medical Eflays; which having the gula im- 
pervious was furnifhed with an aperture into the wind-pipe, 
which communicated below into the gullet; by means of which 
the liquor amnii might be taken into the ftomach before nativity 
without danger of Juffecation, while the fetus had no occafion 
to breathe. The other monftrous fetus is defcribed by Vander 
Wiel, who afl'erts that he faw a monftrous lamb, which had no 
mouth ; but inftead of it was furnifhed with an opening in the 
lower part of the neck into the ftomach. Both thefe inftances 
evidently favour the doCbrine of the fetus being nourifhed by the 
mouth j as otherwife there had been no neceflity for new or 
unnatural apertures into the ftomach, when the natural ones 
were deficient. 
From thefe facts and obfervations we may fafely infer, that 
the fetus in the womb is nourifhed by the fluid which furrounds 
it; which during the firft period of geftation is abforbed by the 
naked laCleals; and is afterwards fwallowed into the ftomach 
4nd bowels, when thefe organs are perfected; and laftly that 
th? 372 
OXYGENATION, &c. 
Sect. XXXVIII. 3. 3. 
the placenta is an organ for the purpofe of giving due oxygena- 
tion to the blood of the fetus ; which is more necellary, or at 
Icalt more frequently neceifary, than even the fupply of food. 
The queftion of the great Harvey becomes thus eafdy anfwer- 
ed. « Why is not the fetus in the womb fuffocated for want 
of air, when it remains there even to the tenth month without 
refpiration: yet if it be born in the feventh or eighth month, 
and has once refpired, it becomes immediately fulfocatcd for 
want of air, if its refpiration be obltrudled ?" 
For further information on this fubject, the reader is referred 
to the Tentamen Medicum of Dr. Jeft'ray, printed at Edinburgh 
in 1786. And it is hoped that Dr. Forefter will fome time 
give his thefes on this fubjeft to the public. 
SECT. Sect. XXXIX. 
GENERATION. 
373 
SECT. XXXIX. 
OF GENERATION. 
Felix, qui caufas aka caligine merfas 
Pandit, et evokit tenuilkrru vincula return. Anon. 
I. Habits of ailing and feeling of individuals attend the foul into a 
future life, and attend the new embryon at the lime of its produc- 
tion. The new fpeck of entity abforbs nutriment, and receives 
cxygene. Spreads the terminations of its veffds on cells, which 
communicate with the arteries of the uterus ; fometimes with thofe 
of the peritoneum. Afterwards it f wallows the liquor amnii, 
which it produces by its irritation from the uterus, or peritoneum. 
Like infects in the heads of calves and fneep. Why the white of 
egg is of two conffencies. Why nothing is found in quadrupeds 
fimilar to the yolk, nor in mojl vegetable feeds. II. I. Eggs 
oj frogs and Jijh impregnated out of their bodies. Fggs of fowls 
which are not fecundated, contain only the nutriment for the embry- 
on. The embryon is produced by the male, and the nutriment by 
the female. Animalcula in femine. Profufion of nature's births. 
2. Vegetables viviparous. Buds and bulbs have each a father but 
no mother. Veffels oj the leaf and bud inofculate. The paternal 
offspring exactly refembles the parent. 3. In feels impregnated for 
fix generations. Polypus branches like buds. Creeping roots. 
Viviparous fowers. Tania, volvox. Eve from Adam's rib. 
Semen not a jlimulus to the egg. 111. 1. Embryons not original- 
ly created within other embryons. Organized matter is not fo mi- 
nute. 2. All the parts of the embryon are not formed in the male 
parent. Crabs produce their legs, worms produce their heads and 
tails. In wens, cancers, and inf animations, new veffels are form- 
ed. Mules partake of the forms of both parents. Hair and 
nails grow by elongation, not by difention. 3. Organic particles 
of Buffon. IV. 1. Rudiment of the embryon a fimple living fla- 
ment, becomes a living ring, and then a living tube. 2. It ac- 
quires new irritabilities, and fenfibilities with new organizations, 
as in wounded fnails, polypi, moths, gnats, fad-poles. Hence new 
parts are acquired by addition not by detention. 3. Ail parts of 
the body grow if not confined. 4. Eetufes deficient at their ex- 
tremities, or have a duplicaiure of parts. Monfirous births. 
Double parts of vegetables. 5. Mules cannot be formed by dif- 
tention of the feminal ens. 6. Families oj animals from a mix- 
ture of their orders. Mules imperfect. 7. Animal appetency 
fike chemical affinity. Vis fabricatrix and medicatrix oj' nature. 
8. The 374 
GENERATION. 
Sect. XXXIX, 
8. The changes of animals before and after nativity. Similarity 
of their JlruAure. Changes in them from lufi, hunger, and 
danger. All warm-blooded animals derivedfrom one living filament. 
Cold-blooded animals, infeAs, worms, vegetables, derived alfo from 
one living filament, Male animals have teats. Male pigeon gives 
milk. The world itfelf generated. The caufe of cattfes. A fate of 
probation and refponfibility. V. i. Efficient caufe of the colours of 
birds' eggs, and of hair and feathers, which become white in fnowy 
countries. Imagination of the female colours the egg. Ideas or 
motions of the retina imitated by the extremities of the nerves of 
touch, or ret e mucofum. 2. Nutriment fupplied by the female of 
three kinds. Her imagination can only affect the firfi kind. 
Mules how produced, and mulattoes. Organs of reproduction why 
deficient in mules. Eggs with double yolks. VI. I. Various fe- 
cretions produced by the extremities of the veffcls, as in the glands. 
Contagious matter. Many glands affected by pleafurable ideas, 
as thofe which fecrete the fetnen. 2. Snails and worms are her- 
maphrodite, yet cannot impregnate themfelves. Final caufe of 
this. 3. The imagination of the male forms the fex. Ideas, or 
motions of the nerves of vifion or of touch, are imitated by the ulti- 
mate extremities of the glands of the tefles, which mark the fex. 
This effect of the imagination belongs only to the male. The fex of 
the embryon is not owing to accident. 4. Caufes of the changes in 
animals from imagination as in monfiers. From the male. Front 
the female. 5. Mifcarriages from fear. 6. Power of the 
imagination of the male, over the colour, form, and fex of the prog- 
eny. An infiance of. 7. Act of generation accompanied with 
ideas of the male or female form. Art of begetting beautiful chil- 
dren of either fex. VIL Recapitulation. VIII. 1. Appendix. 
Buds are individuals. Confifi of plumula caudex and radicle. 
Every part of the caudex can germinate. A triple tree by ingraft- 
ment. A lateral vegetable mule produced by three parents. Con- 
ferva fentin alls. 2. Lateral propagation of polypus, and hydra 
ftentorea. The halves of two polypi made to unite. Ingraft ment 
of vegetables. Lateral mule. 3. New bud of a doubly ingrafted 
tree has three kinds of caudex. Triple mule producedfrom vari- 
ous parts of the parent tree. 4. Earthworms cut afunder gener- 
ate a new head, and a new tail. So the caudexes of the buds of 
trees. The whole embryon not formed at the fame time. 5. Parts 
of the long caudex of the new bud are fecreted from correfpondent 
parts of the parent bud, and unite beneath the cuticle. Every 
part of the caudex can germinate. Thefe new buds refemble the 
part of the flock, •tvhere they arife. Lateral mule from many 
parents. If a triple fexual mule P 6. Gravitation, chemical 
affinity, electricity, magnetifm. Power to attracl. Aptitude to 
be Sect. XXXIX. 
GENERATION. 
375 
be attracted. A magnet pffiffes power to attract, iron an aptitude 
to be attracted. So of elechified bodies, and chemical affinities. 
Or two bodies may reciprocally attract each other. 7. Union of 
animal with inanimate matter. Union of two living particles. 
The animal ferfe pffeffes appetency to unite, the inanimate materi- 
al p off effes aptitude to be united. Vitality of the blood. Fibrils 
with appetencies, molecules with propen/ities. 8. Fibrils with 
formative appetencies. Molecules with formative propensities. 
Like fingle and double affinities. Pafftons of hunger and of love. 
Thirfl. Suckling children. Mode of lateral propagation. <j. 
Superfluous vital particles produced in the blood. Secreted by fex- 
ual glands. Combine beneath the cuticle of trees. Acquire new 
appetencies, and form fecondary parts of the embryon. So the 
paffton for generation, and def re for animal food, and the new at- 
tr actions of bodies chemically combined. New molecules are form- 
ed by the fexual glands at puberty, and in the pectoral ones. IQ. 
Different f brils and molecules are detached from different parts 
of the parent caudex to form the filial one : fo in the f exual propa- 
gation of vegetables : and by their combination produce an embry- 
cn, and acquire new appetencies and form fecondary parts, ms in 
dioecious flowers. 11. Threefold lateral mules. So fexual mules 
referable parts of their parents according to the combinations of the 
fibrils and molecules, and produce fecondary parts, otherwife they 
would refemble the father only. Epigram from Martial. IX. 
I. Various parts of the new embryon produced at the fame time. 
Organized bodies too large to be fecreted. Primary andfecondary 
formation of parts of the fetus. M. Buffon's theory differs from 
this. Moles and monfrous births. An embryon is not an in- 
dividual, till the nerves unite in the brain. 2. The brain and 
heart generated at the fame time. 3. Organic particles too large 
to pafs the glands and capillaries. Not fo the formative particles. 
Hence the latter cannot combine in the blood. 4. Formative par- 
ticles do not combine in the receptacles of the fexualglands, asthefe 
of the male differ from thofe of the female. Not Jo in Buffoiis 
theory. 5. The whole embryon not produced at the fame time. 
Primary and fecondary parts. Secondary formation of the caudex 
of buds, of diffevered earth worms, of the legs of crabs, of human 
teeth, and of a thumb. X. I. Solitary lateral generation, and 
folitary internal generation. Animalized particles of primary 
combination, are fecreted, combine, andform primary organizations. 
The caudex gemma produces fecondary parts, and commences its 
formation in feveral places at the fame time. Refembles the parent 
more than a fexual progeny. The polypus and hydra. 2. Solita- 
ry internal generation of aphis, tenia, actinia, volvox, produces a 
viviparous offspring, not an oviparous one. Difference of lateral 
and 376 
GENERATION. 
Sect. XXXIX. 
and intimal generation. 3. Hermaphrodite fexunl generation 
in mofl flowerSy and fame infeEts. Summit-bulbs offline vegeta- 
bles are a fexual progeny. Sexual organs in hermaphi odites are 
flparatey but flerete the mafculine and feminine formative particles 
from the fame mafs of blood. Why feedlihg apple-trees flmetimes 
referable the parent,flmetimes not. Number offpecies increafedby 
reciprocal generation. 4. In fimple fexual generation the mafcu- 
line and feminine fleretions are from different muffles of blood. 
Thefle animals were originally hermaphrodites. The mode of the 
production of the new embryon. Secretion differs from nutrition. 
New embryon begins in more parts than one. Acquires new ap- 
petencieSy andfabricates fecondary parts. Sexual organs are fleon- 
dary partSy not primary ones. So is the difference of the male and 
female forms. Vegetable and animal fecondary product ions. 5. 
Seeds. Eggs. Spawn differs from eggSy as it enlarges along with 
the embryon like the membranes of the fetus in utero. XI. 1. In- 
animate crflals. Animated organization. Microflopic animal- 
ctda from flagnation of vegetable and animal fluids. Do not 
generate. 2. Second kind of animal production commences in more 
points than one : not like microflopic animals ; as truffles, fungi, 
polypiy hydra. 3. Other vegetables are hermaphrodite, but both 
their flxual glands flerete from the fame mafs of blood. 4. Other 
vegetables have acquired feparate flexes y and flerete the prolific flu- 
ids front different muffles of blood. The embryon begins in more 
points in the more complicated animals. The primary parts fabri- 
cate fecondary ones, as in the clafs dioecia of vegetablesy and in flxu- 
al animals. Nature is yet in her infancy, g. Spontaneous pro- 
duction of microfcopic animalcules. Is fimilar to actual generation. 
The firfi animalcules generate others, and improve. Seedling tu- 
lip-root. Aphis. Immutable laws impreffd on matter. XII. 
Conclufton. Of caufe and effect. The atomic philoflphv leads to 
a firfl caufe. 
I. The ingenious Dr. Hartley in Ins work on man, and Come 
ether philofophers, have been of opinion, that our immortal 
part acquires during this life certain habits of action or of fenti- 
ment, which become for ever indiffbluble, continuing after death 
in a future Rate of exigence ; and add, that if ihele habits are 
of the malevolent kind, they muft render the pofleffor miferable 
even in Heaven. I would apply this ingenious idea to ti e gener- 
ation or production of the embryon, or new animal, which 
partakes fo much of the form and propensities of the parent. 
Owing to the imperfeClion of language the offspring is termed 
a tew animal, but is in truth a branch or elongation of the par- 
ent ; finee a part of the embryon-animal is, or was, a part of the 
parent ; Sect. XXXIX. i. i. 
GENERATION. 
377 
parent; and therefore in ftrict language it cannot be faid to be 
entirely new at the time of its production ; and therefore it may 
retain fome of the habits of the parent-fyftem. 
At the earlieft period of its exiftence the embryon, as fecreted 
from the blood of the male, would feem to confit of a living 
filament with certain capabilities of irritation, fenfation, voli- 
tion, and affociation ; and alfo with fome acquired habits or 
propenfities peculiar to the parent : the former of thefe are in 
common with other animals ; the latter feem to .diftinguilh or 
produce the kind of animal, whether man or quadruped, with 
the fimilarity of feature or form to the parent. It is difficult to 
be conceived, that a living entity can be feparated or produced 
from the blood by the aflion of a gland ; and which ihali after- 
wards become an animal fimilar to that in whofe veflels it is 
formed; even though we Ihould fuppofe with fome modern 
theorifts, that the blood is alive ; yet every other hypothefis con- 
cerning generation refts on principles bill more difficult to our 
comprehenfion. 
At the time of procreation this fpeck of entity is received in- 
to an appropriated nidus, in which it mult acquire two circum- 
ftances neceflary to its life and growth ; one of thefe is food or 
fuftenancei which is to be received by the abforbent mouths of 
its veflels ; and the other is that part of atmofpherical air, or of 
water, which by the new chemiftry is termed oxygene, and 
which affects the blbod by palling through the coats of the vef- 
fels which contain it. The fluid furrounding the embryon in its 
new habitation, which is called liquor ammi, fupplies it with 
nourilhment; and as fome air cannot but be introduced into the 
uterus along with a new embryon, it would feem that this fame 
fluid would for a fhort time, fuppofe for'a few hours, fupply 
likcwife a fufficient quantity of the oxygene for its immediate 
exiftence. 
On this account the vegetable impregnation of aquatic plafits 
is performed in the air ; and it is probable that the honey-cup 
or nectary of vegetables requires to be open to the air, that the 
anthers and ftigmas of the flower may have food of a more 
oxygenated kind than the common vegetable fap-juice. 
On the introduction of this primordium of entity into the 
uterus the irritation of the liquor amnii, which furroundsit, ex- 
cites the abforbent mouths of the new veflels into action ; they 
drink up a part of it, and a pleafurable fenfation accompanies 
this new action ; at the fame time the chemical affinity of the 
oxygene adts through the veflels of the rubefcqnt blood ; and a 
previous want, or difagrceable fenfation, is relieved by this 
procefs. 
Vol- I. A a a As 378 
GENERATION. 
Sect. XXXIX. i .r. 
As tie want of this oxygenation of the blood is perpetual, (as 
appears from the inceflant neceflity of breathing by lungs or 
gills,) the veffels become extended by the efforts of pain or defire' 
to feek this neceffary object of oxygenation, and to remove the 
difagreeable fenfation, which that want occafions. At the fame 
time new particles of matter are abforbed, or applied to thefe 
extended veffels, and they become permanently elongated, as the 
fluid in contact with them foon lofes the oxygenous part, which 
it at firft poffeffed, which was owing to the introduction of air 
along with the embryon. Thefe new blood-veffels approach the 
fides of the uterus, and penetrate with their fine terminations 
into the veffels of the mother j or adhere to them, acquiring 
oxygene through their coats from the paffing currents of the ar- 
terial blood of the mother. See SeCl. XXXVIII. 2. 
This attachment of the placental veffels to the internal fide of 
the uterus by their own proper efforts appears further illuftrated 
by the many inftances of extra-uterine fetufes, which have thus 
attached or inferted their veffels into the peritoneum ; or on the 
vifeera, exactly in the fame manner as they naturally infert or 
attach them to the uterus. 
The abforbent veffels of the embryon continue to drink up 
nouriibment from the fluid in which they fwim, or liquor am- 
nii; and which at firft needs no previous digeftive preparation ; 
but which, when the whole apparatus of digefticn becomes com- 
plete, is fwallowed by the mouth into the ftomach, and being 
mixed with faliva, gaftric juice, bile, pancreatic juice, and mucus 
of the inteftines, becomes digefted, and leaves a recrement, 
which produces the firft feces of the infant, called meconium. 
The liquor amnii is fecreted into the uterus^ as the fetus re- 
quires it, and may probably be produced by the irritation of the 
fetus as an extraneous body ; fince a fimilar fluid is acquired 
from the peritoneum in cafes of extra-uterine geftation. The 
young caterpillars of the'gad-fly placed in the fkins of cows, and 
the young of the ichneumon-fly placed in the backs of the cater- 
pillars on cabbages, feem to produce their nourifhment by their 
irritating the fides of their nidus. A vegetable fecretion and 
concretion arc thus produced on oak-leaves by the gall-infect, 
and by the cynips in the bedeguar of the rofe ; and by the young 
grafshopper on many' plants, by which the animal furrounds it- 
felf with froth. But in no circumftance is extra-uterine gefta- 
tion fo exactly refembled as by the eggs of a fly, which are de- 
pofited in the frontal Gnus of fheep and calves. Thefe eggs float 
in ibrne ounces of fluid collected in a thin pellicle or hydatid. 
This bag of fluid comprefles the optic nerve on one fide, by which 
the vifion being lefs diftinft in that eye, the animal turns in per- 
petual Sect. XXXIX. i.i. 
GENERATION. 
379 
petual circles towards the fide affe&ed, in order to get a more 
accurate view of objects ; for the fame reafon as in fquinting 
•the affe&ed eye is turned away from the object contemplated. 
Sheep in the warm months keep their nofes clofe to the ground 
to prevent this fly from fo readily getting into their noftrils. 
The liquor amnii is fecreted into the womb as it is required, 
not only in refpeeft to quantity, but, as the digeftive powers of the 
fetus become formed, this fluid becomes of a different confift- 
ence and quality, till it is exchanged for milk after nativity. 
Haller. Phyfiol. V. i. In the egg the white part, which is 
analogous to the liquor amnii of quadrupeds, confifts of two 
diftinct parts; one of which is more vifeid, and probably more 
difficult of digeftion, and more nutritive than the other ; and 
this latter is ufed in the laft week of incubation. The yolk of 
the egg is a ftill ftronger or more nutritive fluid, which is drawn 
up into the bowels of the chick juft at its exclufion from the 
(hell, and ferves it for nourilhment for a day or two, till it is 
able to digeft, and has learnt to choofe the harder feeds or grains, 
which are to afford it fuftenance. Nothing analogous to this 
yolk is found in the fetus of lactiferous animals, as the milk is 
another nutritive fluid ready prepared for the young progeny; 
it is alfo a curious circumftance, that the firft milk of female ani- 
mals after parturition is much thicker, like the yolk of egg, and 
much more coagulable, than that which is fecreted after a few 
days, when the digeftive powers of the offspring are become 
ftronger. 
The yolk therefore is not neceffary to the fpawn of fifh, the 
eggs of infefts, or for the feeds of vegetables; as their embry- 
ons have probably their food prefented to them as foon as they 
are excluded from their fhells, or have extended their roots. 
Whence it happens that fome infects produce a living progeny 
in the fpring and fummer, and eggs in the autumn ; and fome 
vegetables have living roots or buds produced in the place of 
feeds, as the polygonum viviparum, and magical onions. See 
Botanic Garden, p. ii. art. Anthoxanthum. 
There feems however to be a refervoir of nutriment prepared 
for fome feeds befides their cotyledons or feed-leaves, which may 
be fuppofed in fome meafure analogous to the yolk of the egg. 
Such are the faccharine juices of apples, grapes, and other fruits, 
which fupply nutrition to the feeds after they fall on the ground. 
And fuch is the milky juice in the centre of the cocoa-nut, and 
part of the kernel of it; the fame I fuppofe of all other monoco- 
tyledon feeds, as of the palms, graffes, and lilies. The milky 
juice in the centre of the cocoa-nut feems curioufly to refemble 
the chyle of animals, as it contains oil diffuied with mucilage 
apd 380 
GENERATION. 
Sect. X3EXIX. 2. if 
and fugar, whence arifes its white colour; whereas the chyle or 
lap-juice of vegetables, which exudes from wounds of birch or 
maple-trees in the vernal months, is tranfparent, and confifts on- 
ly of fugar and mucilage, and in this circumftance differs from 
the chyle of animals. 
II. i. The procefs of generation is (till involved in impene- 
trable obfcurity, conjectures may neverthelefs be formed con- 
cerning fome of its circum(lances. Firft, the eggs of fifh and 
frogs are impregnated, after they leave the body of the female ; 
becaufe they are depolited in a fluid, and are not therefore 
covered with a hard fhell. It is however remarkable, that neither 
frogs nor fifh will part with their fpawn without the prefence 
of the male ; on which account female carp and gold-fifh in 
Imall ponds, where there are no males, frequently die from the 
diftention of their growing fpawn. 2. The eggs of fowls, 
which are laid without being impregnated, are feen to contain 
only the yolk and white, which are evidently the food or fuf- 
tenance for the future chick. 3. As the cicatricula of thefe 
eggs is given by the cock, and is evidently the rudiment of the 
new animal; we may conclude, that the embryon is produced 
by the male, and the proper food and nidus by the female. For 
if the female be fuppofed to form an equal part of the embryon, 
why fhould fhe form the whole of the apparatus for nutriment 
and for oxygenation ? The male in many animals is larger, 
llronger, and digefts more food than the female, and therefore 
fhould contribute as much or more towards the reproduction of 
the fpecies; but if he contributes only half the embryon and 
none of the apparatus for fuftenance and oxygenation, the di- 
vifion is unequal; the ftrength of the male, and his confump- 
tion of food are too great for the efieCt, compared with that of 
the female, which is contrary to the ufual courfe of nature. 
It has been fuppofed by fome inquirers into the procefs of 
generation, that the male femen in many animals could not come 
into contaCl with the ovum of the female, and they have hence 
fuppofed, that an aerial or ethereal emanation from the femen 
virile might ferve the purpefe of ftimulating into life the ovum 
muliebre, becaufe in the vegetable ftigma of fome flowers no 
veflels have been feen to receive and tranfmit the burfting an- 
ther-duft ; and becaufe it is not poflible, that the ejaculatio 
feminis in quadrupeds could fend it through the fallopian tubes 
to the veficles of the ovaria. 
In refpeCl to the analogies from other animals, ift, It may 
be obferved, that in the generation of frogs, it is well known, 
that the male fperm is effufed in contaCl with the female fpawn, 
as it leaves her bodv, and that in fifh the male fperm is likewife 
effufed Sect. XXXIX. 2. 1. 
GENERATION. 
381 
effufed on the female fpawn after its production. 2d. In refpeft 
to vegetables, it mutt be recollected, that their vefl'els are fo mi- 
nute in diameter, that they have not in general been of futheient 
fize to be injeCted by coloured fluids ; and are not thence fo 
vifible by microfcopes as thofe of animals, and that it is probable, 
thofe of the ftigma or piftillum of flowers, which are defigned 
to abforb the folution of the anther-dud, which adheres to the 
moift ftigma, may be always empty, or have their mouths doled, 
except when they are ftimulated into aftion by the anther-duft, 
and may thence more eafily efcape obfervation. Nor do I know, 
that any one has endeavoured to deteCf thefe veflels by experi- 
ments with coloured liquids applied along with the male farina 
on the ftigma for its abforption, or by difleding the piftillum as 
in its recent or dry ftate, or by obferving it in a ftate of charcoal. 
la regard to quadrupeds, Dr. Haighton has (hewn by a num- 
ber of curious experiments on rabbits, publilhed in the Philo- 
foph. TranfaCh for the year 1797, that the male femen does 
not permeate the fallopian tubes, and confequently never arrives 
at the female ova, either in a liquid or aerial ftate ; but that it 
is by the ftimulus of the femen in the neck of the uterus ; that 
the velicles of the ovaria fwell, and difeharge the material, which 
has been called an ovum, though it does not poffefs a diftinguifh- 
able form ; and that this is acquired and carried into the uterus 
by the periftaltic motions of the fallopian tubes, fome hours af- 
ter copulation. Here I fuppofe it finds the male femen, and 
that thus the new animal produced by the fecretion of the male 
finds correfponding nutriment and fituation in the female in all 
fexual progeny. But that no female apparatus is required in the 
production of the buds of trees, or in the adherent fetus of the 
polypus, or of the coral-infeCts. 
In obje&ion io this theory of generation it may be faid, if the 
animalcula in femine, as feen by the microfcope, be ail of them 
rudiments of homunculi, when but one of them can find a nidus, 
what a waile nature has made of her productions ? I do not af- 
fert that thefe moving particles, vifible by the microfcope, are 
homunciones; perhaps they may be the creatures of ftagnation or 
putridity, or perhaps no creatures at all ; but if they are fup- 
pofed to be rudiments of homunculi, or embryons, fuch a pro- 
fufion of them correfponds with the general efforts of nature to 
provide for the continuance of her fpecies of animals. Every 
individual tree produces innumerable feeds, and every individual 
filh innumerable fpawn, in fuch inconceivable abundance as 
would in a Ihort fpace of time crowd the earth and ocean with 
inhabitants; and thefe are much more perfeCl animals than the 
animalcula in femine can be fuppofed to be, and perifli in un- 
counted 382 
GENERATION. 
Sect. XXXIX. 2. 2. 
Counted millions. This argument only (hews, that the produc- 
tions of nature are governed by general laws; and that by a 
wile fuperfluity of provifion fhe has enfured their continuance. 
2. That the embryon is fecreted or produced by the male, 
and not by the conjunction of fluids from both male and female, 
appears from the analogy of vegetable feeds. In the large flow- 
ers, as the tulip, there is no fimilarity of apparatus between the 
anthers and the ftigma: the feed is produced according to the 
obfervations of Spallanzani long before the flowers open, and in 
confecfuence long before it can be impregnated, like the egg in 
the pullet. And after the prolific dull is ihed on the ftigma, 
the feed becomes coagulated in one point firft, like the cicatricu- 
la of the impregnated egg. See Botanic Garden, Part I. addi- 
tional note 38. Now in thefe Ample products of nature, if the 
female contributed to produce the new embryon equally with 
the male, there would probably have been feme vifible fimilarity 
of parts for this purpofe, befides thofe neceflary for the nidus 
and fuftenance of the new progeny. Befides in many flowers 
the males are more numerous than the females, or than the fepa- 
rate uterine cells in their germs, which would fhew, that the of- 
fice of the male was at leaft as important as'that of the female ; 
whereas if the male, befides producing the egg or feed, was to 
produce an equal part of the embryon, the office of reproduction 
would be unequally divided between them. 
Add to this, that in the moft fimple kind of vegetable repro- 
duction, I mean the buds of trees, which are the viviparous 
offspring, the leaf is evidently the parent of the bud, which rifes 
in its bofom, according to the obfervation of Linmeus. This 
leaf confifts of abferbent veffels, and pulmonary ones, to obtain 
its nutriment, and to impregnate it with oxygene. This fimple 
piece of living organization is alfo furnifhed with a power of re- 
production ; and as the new offspring is thus fupported adhering 
to its father, it needs no mother to fupply it with a nidus, and 
nutriment, and oxygenation; and hence no female leaf has 
exiftence. 
I did conceive that the veffels between the bud and the leaf 
communicated or inofculated ; and that the bud was thus ferved 
with vegetable blood, that is, with both nutriment and oxygena- 
tion, till the death of the parent-leaf in autumn. And that in 
this refpeCt it differed from the fetus of viviparous animals. 
But, fince the former editions of this work were publifhed, I 
have been induced to change that opinion ; as on diffeCting the 
bud of the horfe-chefnut, sefculus hippocaftanum, as mentioned 
below, no communication of veffels between the leaf and the bud 
generated in its bofom could be perceived, fo that it is more 
probably Sect. XXXIX. 2. 2. 
GENERATION. 
383 
probably nourifhed by abforbing the fluid, with which it is fur* 
rounded, like the fetus of animals, as fhewn in my work on. 
vegetation, termed Phytologia. Se6t. VII. i. 2. Secondly, I 
conceive that theft the bark-veflels belonging to the dead leaf, and 
in which I fuppofe a kind of manna to have been depofited, be- 
come now the placental veflels, if they may be fo called, of the 
new bud. From the vernal fap thus produced of one fugar-ma- 
ple-tree in New-York and in Pennfylvania, five or fix pounds of 
good fugar may be made annually without deftroying the tree. 
Account of maple-fugar by B. Rufh. London, Phillips. (See 
Botanic Garden, Part I. additional note on vegetable placenta- 
tion.) 
Thefe veflels, when the warmth of the vernal fun hatches the 
young bud, ferve it with a faccharine nutriment, till it acquires 
leaves of its own, and fhoots a new lyftem of abforbents down 
the bark and root of the tree, juft as the farinaceous or oily mat- 
ter in feeds, and the faccharine matter in fruits, ferve their em- 
bryons with nutriment, till they acquire leaves and roots. This 
analogy is as forcible in fo obfcurc a fubject, as it is curious, and 
may in large buds, as of the horfe-chefnut, be almoft feen by the 
naked eye; if with a penknife the remaining rudiment of the 
laft year's leaf, and of the new bud in its bofom, be cut away 
flice by flice. The feven ribs of the laft year's leaf will be fecn 
to have arifen from the pith in feven diftindl points making a 
curve ; and the new bud to have been produced in their centre, 
and to have pierced the alburnum and cortex, and grown with- 
out the affiftance of a mother. A fimilar procefs may be feen 
on diflerTing a tulip-root in winter ; the leaves, which enclofed 
the laft year's flower-ftalk, were not neceffary for the flower ; 
but each of thefe was the father of a new bud, which may be 
now found at its bafe; and which, as it adheres to the parent, 
required no mother. 
This paternal offspring of vegetables, I mean their buds and 
bulbs, is attended with a very curious circumftance ; and that 
is, that they exactly refemble their parents, as is obfervable in 
grafting fruit trees, and in propagating flower-rooti; whereas 
the feminal offspring of plants, being fupplied with nutriment 
by the mother, is liable to perpetual variation. Thus alfo in the 
vegetable clafs dioecia, where the male flowers are produced on 
one tree, and the female ones on another ; the buds of the male 
trees uniformly produce either male flowers, or other buds fimi- 
lar to themfelves ; and the buds of the female trees produce 
either female flowers, or other buds fimilar to themfelves ; 
whereas the feeds of thefe trees produce either male or femals 
plants. From this analogy of the production of vegetable buds 
without 384 
GENERATION. 
Sect. XXXIX. 2. 3, 
without a mother, I contend that the mother does not contribute 
to the formation of the living ens in animal generation, but is 
fjeceffary only for fupplying its nutriment and oxygenation. 
There is another vegetable fatt publifhed by M. Koelreuter,- 
which he calls " a complete metamorphofis of one natural fpe- 
qies of plants into another," which (hews, that in feeds as well 
as in buds, the embryon proceeds from the male parent, though 
the form of the fubfequent mature plant is in part dependent on 
the female. M. Koelreuter impregnated a lligma of the nico- 
tiana ruflica with the farina of the nicotiana paniculata, and ob- 
tained prolific feeds from it. With the plants which fprung 
from thefe feeds, he repeated the experiment, impregnating them 
with the farina of the nicotiana paniculata. As the mule plants 
which he thus produced were prolific, he continued to impreg- 
nate them for many generations with the farina of the nicotiana 
paniculata, and they became more and more like the male par- 
ent, till he at length obtained fix plants in every refpedt perfect- 
ly fimilar to the nicotiana paniculata; and in no refpect refem- 
bling their female parent the nicotiana rullica. Blumenbacb on 
Generation. 
3. It is probable that the infefls, which are faid to require but 
one impregnation for fix generations, as the aphis (fee Amenit., 
Academ.) produce their progeny in the manner above defcribed, 
that is, without a mother, and not without a father ; and thuo 
experience a lucina fine concubitu. Thofe who have attended 
to the habits of the polypus, which is found in the llagnant wa- 
ter of our ditches in July, affirm, that the young ones branch out 
from the fide of the parent like the buds of trees, and after a 
time feparate themfelves from them. This is fo analogous to 
the manner in which the buds of trees appear to be produced, 
that thefe polypi may be conlidered as all male animals, produ- 
cing embryons, which require no mother to fupply them with a 
nidus, or with nutriment, and oxygenation. 
This lateral or lineal generation of plants, not only obtains in 
the buds of trees, which continue to adhere to them, but is 
beautifully feen in the wires of knot-grafs, polygonum aviculare, 
and in thofe of ftrawberries, fragaria vefca. In thefe an elonga- 
ted creeping bud is protruded, and, where it touches the ground, 
takes root, and produces a new plant derived from its father, 
from which it acquires both nutriment and oxygenation ; and 
in confequence needs no maternal apparatus for thefe purpofes. 
In viviparous flowers, as thofe of allium magicum, and polygo- 
num viviparum, the anthers and the itigmas become effete and 
perifh ; and tire lateral or paternal offspring fuccecd inllead of 
feeds, Sect. XXXIX. 3. 1. 
GENERATION. 
385 
feeds, which adhere till they are fufficiently mature, and then fall 
upon the ground, and take root like other bulbs. 
The lateral production of plants by wires, while each new 
plant is thus chained to its parent, and continues to put forth 
another and another, as the wire creejf& onward on the ground, 
is exaCtly refembled by the tape-worm, or taenia, fo often found 
in the bowels, ftretching itfelf in a chain quite from the ftom- 
ach to the reClum. Linnaeus aflerts, " that it grows old at one 
extremity, while it continues to generate young ones at the oth- 
er, proceeding ad infinitum, like a root of grafs. The feparate 
joints are called gourd-worms, and propagate new joints like the 
parent without end, each joint being furnifhed with its proper 
mouth, and organs of digeftion." Syftema naturae. Vermes 
tenia. In this animal there evidently appears a power of repro- 
duction without any maternal apparatus for the purpofe of fup- 
plying nutriment and oxygenation to the embryon, as it remains 
attached to its father till its maturity. The volvox globator, 
which is a tranfparent animal, is faid by Linnaeus to bear within 
it fons and grand-fons to the fifth generation. Thefe are prob- 
ably living fetufes, produced by the father, of different degrees 
of maturity, to be detruded at different periods of time, like the 
unimpregnated eggs of various fizes, which are found in poul- 
try ; and as they are produced without any known copulation, 
contribute to evince, that the living embryon in other orders of 
animals is formed by the male parent, and not by the mother, as 
one parent has the power to produce it. 
This idea of the reproduction of animals from a tingle living 
filament of their fathers, appears to have been fhadowed or al- 
legorized in the curious account in facred writ of the formation 
of Eve from a rib of Adam. 
From all thefe analogies I conclude, that the embryon is pro- 
duced folely by the male, and that the female fupplies it with a 
proper nidus, with fuftenance, and with oxygenation; and that 
the idea of the femen of the male conftituting only a ftimulus to 
the egg of the female, exciting it into life, (as held by fome phi- 
lofophers) has no fupport from experiment or analogy. 
III. i. Many ingenious philofophers have found fo great 
difficulty in conceiving the manner of the reproduction of ani- 
mals, that they have fuppofed all the numerous progeny to have 
exifted in miniature in the animal originally created ; and that 
thefe infinitely minute forms are only evolved or diftended as 
the embryon increafes in the womb. This idea, befides its being 
unfupported by any analogy we are acquainted with, afcribes a 
greater tenuity to organized matter, than we can readily admit; 
as thefe included embryons are fuppofed each of them to confift 
Vol. I.. B b b of 386 
GENERATION. 
Sect. XXXIX. 3. 2. 
of the various and complicate parts of animal bodies : they mull 
poffefs a much greater degree of minutenefs, than that which 
was afcribed to the devils that tempted St. Anthony ; of whom 
20,000 were faid to have been able to dance a faraband on the 
point of the fineft needle without incommoding each other. 
2. Others have fuppofed, that all the parts of the embryon are 
formed in the male, previous to its being depofited in the egg or 
uterus ; and that it is then only to have its parts evolved or dif- 
tended as mentioned above ; but this is only to get rid of one 
difficulty by propofing another equally incomprehenfible: they 
found it difficult to conceive, how the embryon could be formed 
in the uterus or egg, and therefore wiffied it to be formed before 
it came thither. In anfwer to both thefe doctrines it may be ob- 
ferved, ift. that fome animals, as the crab-fifh, can reproduce 
a whole limb, as a leg which has been broken off; others, as 
worms and fnails, can reproduce a head, or a tail, when either 
of them has been cut away j and that hence in thefe animals at 
lealt a part can be formed anew, which cannot be fuppofed to 
have exifted previoufly in miniature. 
Secondly, there are new parts or new veffels produced in 
many difeafes, as on the cornea of the eye in ophthalmy, in wens 
and cancers, which cannot be fuppofed to have had a prototype 
or original miniature in the embryon. 
Thirdly, how could mule-animals be produced, which partake 
of the forms of both the parents, if the original embryon was a 
miniature exifting in the femen of the male parent ? if an em- 
bryon of the male afs was only expanded, no refemblance to the 
mare could exift in the mule. 
This miftaken idea of the extenfion of parts feems to have had 
its rife from the mature man refembling the general form of the 
fetus ; and from thence it was believed, that the parts of the 
fetus were diftended into the man ; whereas they have increafed 
100 times in weight, as well as too times in fize ; now no one 
will call the additional ninety-nine parts a diftention of the 
original one part in refpeft to weight. Thus the uterus during 
pregnancy is greatly enlarged in thicknefs and folidity as well as 
in capacity, and hence mutt have acquired this additional fize 
by accretion of new parts, not by an extenfion of the old ones; 
the familiar aft of blowing up the bladder of an animal recently 
llaughtered has led our imaginations to apply this idea of dif- 
tention to the increafe of fize from natural growth ; which 
however muff be owing to the appofition of new parts; as it is 
evinced from the increafe of weight along with the increafe of 
dimenfion ; and is even vifible to our eyes in the elongation of 
our hair from the colour of its ends ; or when it has been dyed 
on Sect. XXXIX. 3. 3. 
GENERATION. 
387 
on the head; and in the growth of our nails from the fpecks 
fometimes obfervable on them; and in the increafe of the white 
crefcent at the roots, and in the growth of new flefh in wounds, 
which confifts of new nerves as well as of new blood-veflels. 
3. Laftly, Mr. Buffon has with great ingenuity imagined the 
exiftence of certain organic particles, which are fuppofed to be 
partly alive, and partly mechanic fprings. The latter of thefe 
were difcovered by Mr. Needham in the milt or male organ of a 
fpecies of cuttie fifh, called calmar; the former, or living animal- 
cula, are found in both male and female fecretions, in the infufions 
of feeds, as of pepper, in the jelly of roafted veal, and in all other 
animal and vegetable fubltances. Thefe organic particles he 
fuppofes to exift in the fpermatic fluids of both fexes, and that 
they are derived thither from every part of the body, and muft 
therefore refemble, as he fuppofes, the parts from whence they 
are derived. Thefe organic particles he believes to be in con- 
flant activity, till they become mixed in the womb, and then 
they inftantly join and produce an embryon or fetus fimilar to 
the two parents. 
Many objections might be adduced to this ingenious theory; 
I fhall only mention two. Firft, that it is analogous to no 
known animal laws. And fecondly, that as thefe fluids, replete 
with organic particles derived both from the male and female 
organs, are fuppofed to be fimilar ; there is no reafon why the 
mother fhould not produce a female embryon without the af- 
fiftance of the male, and realize the lucina fine concubitu. See 
No. 8 and 9 of this feCtion, and SeCt. XXXVII. 3. 
IV. 1. I conceive the primordium, or rudiment of the em- 
bryon, as fecreted from the blood of the parent, to confifl. of a 
Ample living filament as a mufcular fibre ; which I fuppofe to 
be an extremity of a nerve of locomotion, as a fibre of the reti- 
na is an extremity of a nerve of fenfation ; as for inftance one 
of the fibrils, which conipofe the mouth of an abforbent veflel; 
I fuppofe this living filament, of whatever form it may be, wheth- 
er fphere, cube, or cylinder, to be endued with the capability of 
being excited into atlion by certain kinds of ftimulus. By the 
ftimulus of the furrounding fluid, in which it is received from 
the male, it may bend into a ring : and thus form thebeginning 
of a tube. Such moving filaments, and fuch rings, are defcribed 
by thofe, who have attended to microfcopic animalcula. This 
living ring may now embrace or abforb a nutritive particle of 
the fluid, in which it fwims ; and by drawing it into its pores, or 
joining it by compreflionto its extremities, may increafe its own 
length or craflitude ; and by degrees the living ring may become 
a living tube. 
2. With 388 
GENERATION. 
Sect. XXXIX. 4. 2. 
2. With this new organization, or accretion of parts, new 
kinds of irritability may commence ; for fo long as there was 
but one living organ, it could only be fuppofed to poflefs irrita- 
bility ; fince fenfibility may be conceived to be an extenfion of 
the effect of irritability over the reft of the fyftem. Thefe new 
kinds of irritability and of fenfibility in confequence of new or- 
ganization, appear from variety of facts in the more mature ani- 
mal ; thus the formation of the tefles, and confequent fecretion 
of the femen, occafion the paflion of luft; the lungs mult be 
previoufly formed before their exertions to obtain frelh air can 
exift; the throat or cefophagus muft be formed previous to the 
fenfation or appetites of hunger and thirft; one of which feems 
to refide at the upper end, and the other at the lower end of 
that canal. 
Thus alfo the glans penis, when it is dillended with blood, 
acquires a new fenfibility, and a new appetency. The fame oc- 
curs to the nipples of the breafts of female animals ; when they 
are diftended with blood, they acquire the new appetency of 
giving milk. So inflamed tendons and membranes, and even 
bones, acquire new fenfations; and the parts of mutilated ani- 
mals, as of wounded fnails, and polypi, and crabs, are reprodu- 
ced ; and at the fame time acquire fenfations adapted to their 
fituations. Thus when the head of a fnail is reproduced after 
decollation with a fharp rafor, thofe curious telefcopic eyes are 
alfo reproduced, and acquire their fenfibility to light,' as well 
as their adapted mufcles for retraction on the approach of 
injury. 
With every new change, therefore, of organic form, or addir 
tion of organic parts, I fuppofe a new kind of irritability or of 
fenfibility to be produced ; fuch varieties of irritability or of fen- 
fibility exift in our adult ftate in the glands ; every one of which 
is furniftied with an irritability, or a tafte, or appetency, and a 
confequent mode of action peculiar to itfelf. 
In this manner I conceive the veflels of the jaws to produce 
the teeth, thofe of the fingers to produce the nails, thofe of the 
Ikin to produce the hair j in the fame manner as afterwards 
about the age of puberty the beard and other great changes in 
the form of the body, and difpofition of the mind, are produced 
in confequence of the new fecretion of femen ; for if the animal 
is deprived of this fecretion thofe changes do not take place. 
Thefe changes I conceive to be formed not by elongation or dif- 
tention of primeval ftamina, but by appofition of parts ; as the 
mature crab-fifh, when deprived of a limb, in a certain fpace of 
time has power to regenerate it; and the tadpole puts forth its 
feet long after its exclufion from the ipawn; and the caterpil- 
lar Sect. XXXIX. 4. 2. 
GENERATION. 
389 
lar in changing into a butterfly acquires a new form, with new 
powers, new fenfations, and new defires. 
The natural hiftory of butterflies, and moths, and beetles, 
and gnats, is full of curiofity ; fome of them pafs many months, 
and others even years, in their caterpillar or grub ftate; they 
then reft many weeks without food, fufpended in the air, buried 
in the earth, or fubmerfed in water : and change themfelves 
during this time into an animal apparently of a different nature ; 
the ftomachs of fome of them, which before digefted vegetable 
leaves or roots, now only digeft honey ; they have acquired 
wings for the purpofe of feeking this new food, and a long pro- 
bofcis to collect it from flowers, and I fuppofe a fenfe of fmell to 
detect the fecret places in flowers, where it is formed. The 
moths, which fly by night, have a much longer probofcis rolled 
up under their chins like a watch fpring ; which they extend to 
coiled the honey from flowers in their fleeping ftate ; when they 
are clofed, and the nectaries in confequence more difficult to be 
plundered. The beetle kind are furniflied with an external 
covering of a hard material to their wings, that they may occa- 
fionally again make holes in the earth, in which they palled the 
former ftate of their exiftence. 
But what molt of all diftinguifhes thefe new animals is, that 
they are now furnilhed with the powers of reproduction ; and 
that they now differ from each other in fex, which does not ap- 
pear in their caterpillar or grub ftate. In fome of them the 
change from a caterpillar into a butterfly or moth feems to he 
accomplifhed for the foie purpofe of their propagation ; fmce 
they immediately die after this is finilhed, and take no food in 
the interim, as the filk-worm in this climate; though it.is poffi- 
ble it might take honey as food, if it was prefented to it. For 
in general it would feem, that food of a more ftimulating kind, 
the honey of vegetables inftead of their leaves, was neceflary for 
the purpofe of the feminal reproduction of thefe animals, exaCtiy 
fimilar to what happens in vegetables ; in thefe the juices of the 
earth are fufficient for their purpofe of reproduction by buds or 
bulbs; in which the new plant feems to be formed by irritative 
motions, like the growth of their other parts, as their leaves or 
roots ; but for the purpofe of feminal or amatorial reproduction, 
where fenfation is required, a more ftimulating food becomes 
neceflary for the anther and ftigma ; and this food is honey 
as explained in Sect. XIII. on Vegetable Animation. 
The gnat and the tadpole refemble each other in their change 
from natant animals with gills into aerial animals with lungs.; 
and in their change of the element in which they live; and proba- 
bly of the food, with which they are fappotted ; and laftly, with 
their 390 
GENERATION. 
Sect. XXXIX. 4. j. 
their acquiring in their new hate the difference of fex, and the 
organs of feminal or amatorial reproduction. While the poly- 
pus, who is their companion in their former ftate of life, not 
being allowed to change his form and clement, can only propa- 
gate like vegetable buds by the fame kind of irritative motions, 
which produces the growth of his own body, without the femi- 
nal or amatorial propagation, which requires fenfation ; and 
which in gnats and tadpoles feems to require a change both of 
food and of refpiration. 
From hence I conclude, that with the acquifition of new parts, 
new fenfations, and new defires, as well as new powers, are 
produced ; and thi§ by accretion to the old ones, and not by dif- 
tention of them. And finally, that the molt effential parts of 
the fyftem, as the brain for the purpofe of diftributing the pow- 
er of life, and the placenta for the purpofe of oxygenating the 
blood, and the additional abforbent veffels for the purpofe of ac- 
quiring aliment, are firft formed by the irritations above men- 
tioned, and by the pleafurable fenfations attending thofe irrita- 
tions, and by the exertions in confequence of painful fenfations, 
fimilar to thofe of hunger and fuffocation. After thefe an ap- 
paratus of limbs for future ufes, or for the purpofe of moving 
the body in its prefent natant ftate, and of lungs for future ref- 
piration, and of teftes for future reproduction, are formed by the 
irritations and fenfations, and confequent exertions of the parts 
previoufly exifting, and to which the new parts are to be attached. 
3. In confirmation of thefe ideas it may be obferved, that all 
the parts of the body endeavour to grow, or to make additional 
parts to thcmfclves throughout our lives ; but are reftrained by 
the parts immediately containing them ; thus, if the fkin be taken 
away, the flelhy parts beneath foon fhoot out new granulations, 
called by the vulgar proud fleih. If the periolteum be removed, 
a fimilar growth commences from the bone. Now in the cafe 
of the imperfect embryon, the containing or confining parts are 
not yet fuppofed to be formed, and. hence there is nothing to re- 
ftrain its growth. 
4. Bv the parts of the embryon being thus produced by new 
appofitions, many phenomena both of animal and vegetable pro- 
ductions receive an eaficr explanation ; fuch as that many fctul- 
es are deficient at the extremities, as in a finger or a toe, or in 
the end of the tongue, or in what is called a hare-hp with de- 
ficiency of the palate. For if there Ihould be a deficiency in 
the quantity of the firft nutritive particles laid up in the egg lor 
the reception of the firft living filament, the extreme parts, as 
being laft formed, mult fhew this deficiency by their being im- 
nerfeCt. 
This Sect. XXXIX. 4. 5. 
GENERATION. 
391 
This idea of the growth of the embryon accords allo with the 
production of fome monftrous births, which confift of a duplica- 
ture of the limbs, as chickens with four legs; which could not 
occur, if the fetus was formed by the diftention of an original 
ftamen, or miniature. For if there fhould be a fuperfluity of 
the firft nutritive particles laid up in the egg for the firit living 
filament; it is eafy to conceive, that a duplicature of fome parts 
may be formed. And that fuch foperfluous nourilhment fome- 
times exilts, is evinced by the double yoiks in fome eggs, which 
I fuppofe were thus formed previous to their impregnation by the 
exuberant nutriment of the hen. 
This idea is confirmed by the analogy of the mongers in the 
vegetable world alfo; in which a duplicate or triplicate produc- 
tion of various parts of the flower is obfervable, as a triple neCla- 
ry in fome columbines, and a triple petal in fome ptimrofes ; 
and which are fuppofed to be produced by abundant nourifh- 
ment. 
5. If the embryon be received into a fluid, the ftimulus of 
which is different in fome degree from the natural, as in the 
production of mule-animals, the new irritabilities or fen Abilities 
acquired by the increafing or growing organized parts may differ, 
and thence produce parts not fimilar to the father, but of a kind 
belonging in part to the mother ; and thus, though the original 
ftamen or living ens was derived totally from the father, yet new 
irritabilities or lenfibilities being excited, a change of form cor- 
Tefponding with them will be produced. Nor could the pro- 
duction of mules exift, if the ftamen or miniature of all the 
parts of the embryon is previoufly formed in the male femen., 
and is only diftended by nourilhment in the female uterus. 
Whereas this difficulty ceafcs, it the embryon be fuppofed to 
confift of a living filament, which acquires or makes new parts 
with new irritabilities, as it advances its growth. 
The form, folidity, and colour, of the particles of nutriment 
laid up for the reception of the firft living filament, as well as 
their peculiar kind of ftimulus, may contribute to produce a dif- 
ference in the form, folidity, and colour of the fetus, fo as to re- 
femble the mother, as it advances in life. This alfo may el- 
pecially happen during the firft ftate of the exiftence of the 
embryon, before it has acquired organs, which can charge thefe 
firft nutritive particles, as explained in No. 5. 2. of this SeCtion. 
And as thelc nutritive particles are fuppofed to be fimilar to 
thole, which are formed for her own nutrition, it follows that 
the fetus Ihould fo far refemble the mother. 
This explains, why hereditary difeafes may be derived either 
hom the male or female parent, as well as the peculiar form of 
. -either 392 
GENERATION. 
Sect. XXXIX. 4.6-. 
either of their bodies. Some of thefe hereditary difeafes are 
fimply owing, to a deficient activity of a part of the fyftem, as of 
rhe abforbem veflels, which open into the cells or cavities of the 
body, and thus occafion dropfies. Others are at the fame time 
owing to an increafe of fenfation, as in fcrofula and confump- 
tion ; in thefe the obftrullion of the fluids is firft caufed by the 
inirritability of the veflels, .and the inflammation and ulcers 
which fucceed, are caufed by the conftquent increafe of fen fa- 
tion in the obftrufted part. Other hereditary difeafes, as the 
epilepfy, and other convuliions, confift in too great voluntary 
exertions in confequencc of difagreeablc fenfation in fome par- 
ticular difeafed part. Now as the pains, which occafion thefe 
convulfions, are owing to defeat of the aflion of the difeafed 
part, as (hewn in Se<ft. XXXIV. it is plain, that all thefe heredi- 
tary difeafes may have their origin either from defective irrita- 
bility derived from the father, or from deficiency of the ftimu- 
lus of the nutriment derived from the mother. In either cafe 
the effect. would be fimilar; as a fcrofulous race is frequently 
produced among the poor from the deficient ftimulus of bad 
diet, or of hunger ; and among the rich, by a deficient irritabili- 
ty from their having been long accuftomed to too great ftimulus, 
as of vinaus fpirit. 
6. From this account of reproduction it appears, that all ani- 
mals have a fimilar origin, viz. from a fingle living filament ; 
and that the difference of their forms and qualities has arifen 
only from the different irritabilities and fenfibilities, or volunta- 
rities, or affbeiabilities, of this original living filament; and per- 
haps in fome degree from the different forms of the particles of 
the fluids, by which it has been ar firit ftimulated into activity. 
And that from hence, as Linneus has conjectured in rcfpect to 
the vegetable world, it is not imycffible, but the great variety of 
fpecies of animals, which now tenant the earth, may have had 
their origin from the mixture of a few natural orders. And 
that thofe animal and vegetable mules, which could continue 
their fpecies, have done fo, and conftitute the numerous families 
of animals and vegetables which now exift ; and that thofe 
mules, which were produced with imperfect organs of genera- 
tion, perifhed without reproduction, according to the obferva- 
tion. of Ariftotle ; and are the animals, which we now call mules. 
Sec Botanic Garden, Part IL Note on Diamhus. 
Such a promifeuous intercourfe of animals is laid to exift at 
this day in New South Wales by Captain Hunter. And that 
not only amongft the quadrupeds and birds of different kinds, 
but even amongft the fifh, and, as he believes, amongft the 
vegetables. He fpcaks of an animal between the opoffum and 
the. Sect. XXXIX. 4. 7. 
GENERATION. 
393 
the kangaroo, from the fize of a fheep to that of a rat. Many 
fiffi feemed to partake of the (hark ; fome with a ikait's head 
and (boulders, and the hind part of a (hark ; others with a 
(bark's head and the body of a mullet; and fome with a (hark's 
head and the flat body of a (ting-ray. Many birds partake of 
the parrot; fome have the head, neck, and bill of a parrot, with 
long (iraight feet and legs; others with legs and feet of a par- 
rot, with head and neck of a fea-gull. Voyage to South "Wales 
by Captain John Hunter, p. 68. 
7. All animals therefore, I contend, have a fimilar caufe of 
their organization, originating from a (ingle living filament, en- 
dued indeed with different kinds of irritabilities and fenfibilitiesi 
or of animal appetencies ; which exift in every gland, and in 
every moving organ of the body, and are as effential to living 
organization as chemical affinities are to certain combinations of 
inanimate matter. 
If I might be indulged to make a fimile in a philofophical 
work, I fhould fay, that the animal appetencies, are not only per- 
haps lefs numerous originally than the chemical affinities; but 
that like thefe latter, they change with every new combination ; 
thus vital air and azote, when combined, produce nitrous acid ; 
which now acquires the property of diflblving filver ; fo with 
every new additional part to the embryon, as of the throat or 
lungs, I fuppofe a new animal appetency to be produced. 
In this early formation of the embryon from the irritabilities, 
fenfibilities, and aflbciabilities, and confeqUent appetencies, the 
faculty of volition can fcarcely be fuppofed to have had its birth. 
For about what can the fetus deliberate when it has no choice of 
objects ? But in the more advanced date of the fetus, it evident- 
ly poflefles volition ; as it frequently changesits attitude, though 
it feems to deep the greateft part of its time ; and afterwards 
the power of volition contributes to change or alter many parts 
of the body during its growth to manhood, by our early modes 
of exertion in the various departments of life. All thefe facul- 
ties then confl.itute the vis fabricatrix, and the vis confervatrix, 
as well as the vis medicatrix of nature, fo much fpoken of, but 
fo little underflood by philofophers. 
8. When we revolve in our minds, firft, the great changes, 
which we fee naturally produced in animals after their nativity, 
as in the production of the butterfly with painted wings from 
the crawling caterpillar; or of the relpiring frog from the fub- 
natant tadpole ; from the feminine boy to the bearded man, and 
from the infant girl to the laCtefcent woman; both which 
changes may be prevented by certain mutilations of the glands 
neceflary to reproduction. 
Vol. I. Ccc Secondly, 394 
GENERATION. 
Sect. XXXIX. 4. Si 
Secondly, when we think over the great changes introduced in-* 
to various animals by artificial or accidentalcultivation, as in horfes> 
which we have exercifed for the different purpofes of ftrength or 
fwiftnefs, in carrying burthens or in running races ; or in dogs, 
which have been cultivated for ftrength and courage, as the bull- 
dog ; or for acutenefs of his fenfe of fmell, as the hound and 
fpaniel; or for the fwiftnefs of his foot, as the greyhound ; or for 
bis fwimming in the water, or for drawing fnow-ffedges, as the 
rough-haired dogs of the north ; or laftly, as a play-dog for 
children, as the lap-dog; with the changes of the forms of the 
cattle, which have been domefticated from the greateft antiquity^ 
as camels, and fheep ; which have undergone fo total a transfor- 
mation, that we are now ignorant from what fpecies of wild ani- 
mals they had their origin. Add to thefe the great changes of 
ihape and colour, which we daily fee produced in fmaller ani- 
mals from our domeftication of them, as rabbits, or pigeons ; or 
from the difference of climates and even of feafons; thus the 
fheep of warm climates are covered with hair inftead of wool; 
and the hares and partridges of the latitudes, which are long buri- 
ed in fnow, become white during the winter months; add to 
thefe the various changes produced in the forms of mankind, by 
their early modes of exertion ; or by the difeafes occafioncd by 
their habits of life j both of which became hereditary, and that 
ti rough many generations.- Thofe who labour at the anvil, the 
oar, or the loom, as well as thofe who carry fedan-chairs, or who 
have been educated to dance upon the rope, are diftinguifhable 
by the fhape of their limbs ; and the difeafes occafioned by in- 
toxication deform the countenance with leprous eruptions, or the 
body with tumid vifeera, or the joints with knots and diftortions. 
Thirdly, when we enumerate the great changes produced in 
the fpecies of animals before their nativity ; thefe are fuch as 
refemble the form or colour of their parents, which have been 
altered by the cultivation or accidents above related, and are 
thus continued to their pofterity. Or they are changes produ- 
ced by the mixture of fpecies as in mules ; or changes produced 
probably by the exuberance of nourifhment fupplied to the fe- 
tus, as in monftrous births with additional limbs ; many of thefe 
enormities of fhape arc propagated, and continued as a variety 
at leaft, if not as a new fpecies of animal. I have feen a breed 
of cats with an additional claw on every foot; of poultry alfo 
with an additional claw, and with wings to their feet ; and of 
others without rumps. Mr. Buffon mentions a breed of dogs 
without tails, which arc common at Rome and at Naples, which 
he fuppoles to have been produced by a cuftom long eftabhflicd 
of cutting their t ails clofe off. There are many kinds of pigeons, 
admired Sect. XXXIX. 4. 8. 
GENERATION. 
395 
admired for their peculiarities, which are monitors thus produ- 
ced and propagated. And to thefe mutt be added, the changes 
produced by the imagination of the male parent, as will be treat- 
ed of more at large in No. VI. of this Section. 
When we conlider all thefe changes of animal form, and in- 
numerable others, which may be colietied from the books of nat- 
ural hiftory ; we cannot but be convinced, that the fetus or em- 
■bryon is formed by apportion of new parts, and not by the dis- 
tention of a primordial neft of germes, included one within an- 
other, like the cups of a conjurer. 
Fourthly, when we revolve in our minds the great fimilarity 
of ftrucSlure which obtains in all the warm blooded animals, as 
well quadrupeds, birds, and amphibious animals, as in mankind ; 
from the moufe and bat to the elephant and whale; one is led. 
to conclude, that they have alike been produced from a fimilar 
living filament. In fome this filament in its advance to maturi- 
ty has acquired hands and fingers, with a fine fenfe of touch, as 
in mankind. In others it has acquired claws or talons, as in 
tygcrs and eagles. In others, toes with an intervening web, or 
membrane, as in feals and geefe. In others it has acquired clo- 
ven hoofs, as in cows and fwine ; and whole hoofs in others, as 
in the horfe. While in the bird kind this original living fila- 
ment has put forth wings inftead of arms or legs, and feathers 
inftead of hair. In fome it has protruded horns on the fore- 
head inftead of teeth in the fore part of the upper jaw; in 
others tulhes inftead of horns ; and in others beaks inftead of 
either. And all this exactly as is daily feen in the tranfmuta- 
tions of the tadpole, which acquires legs and lungs, when he 
wants them ; and lofes his tail, when it is no longer of fervice 
to him. 
Fifthly, from their firft rudiment, or primordium, to the ter- 
mination of their lives, all animals undergo perpetual transform- 
ations ; which are in part produced by their own exertions in 
confequence of their defires and averfions, of their pleafures and 
their pains, or of irritations, or of aflbciations ; and many of 
thefe acquired forms or propenfities are tranfmitted to their 
pofterity. See Se6t. XXXI. i. 
As air and water are fupplied to animals in fuflicient profu- 
fion, the three great objects of defire, which have changed the 
forms of many animals by their exertions to gratify them, are 
thofe of lull, hunger, and lecurity. A great want of one part 
of the animal world has confifted in the defire of the exclufive 
poffeflion of the females ; and thefe have acquired weapons to 
combat each other for this purpofe, as the very thick, fhield-like, 
horny fkin on the fhoulder of the boar is a defence only againft 
animals 396 
GENERATION. 
Sect. XXXIX. 4. 8. 
animals of his own fpecies, who (trike obliquely upwards, nor 
are his tufhes for other purpofes, except to defend himfelf, as he 
is not naturally a carnivorous animal. So the horns of the flag 
are {harp to offend his adverfary, but are branched for the pur- 
pofe of parrying or receiving the thrufts of horns fimilar to his 
own, and have therefore been formed for the purpofe of com- 
bating other flags for the exclufive pofleflion of the females ; 
who are obferved, like the ladies in the times of chivalry, to at- 
tend the car of the viftor. 
The birds, which do not carry food to their young, and do 
not therefore marry, are armed with fpurs for the purpofe of 
fighting for the exclufive poffeffion of the females, as cocks and 
quails. It is certain that thefe weapons are not provided for 
their defence againft other adverfaries, becaufe the females of 
thefe fpecies are without this armour. The final caufe of this 
contcfi amongft the males feems to be, that the ftrongeft and 
molt active animal fhould propagate the fpecies, which fhould 
thence become improved. 
Another great want confifts in the means of procuring food, 
which has diverfified the forms of all fpecies of animals. Thus 
the nofe of the fwine has become hard for the purpofe of turn- 
ing up the foil in fearch of infects and of roots. The trunk of 
the elephant is an elongation of the nofe for the purpofe of pull- 
ing down the branches of trees for his food, and for taking up 
water without bending his knees. Beafts of prey have acquired 
llrong jaws or talons. Cattle have acquired a rough tongue 
•and a rough palate to pull off the blades of grafs, as cows and 
fheep. Some birds have acquired harder beaks to crack nuts, as 
the parrot. Others have acquired beaks adapted to break the 
harder feeds, as fparrows. Others for the fofter feeds of flowers, 
or the buds of trees, as the finches. Other birds have acquired 
long beaks to penetrate the moilter foils in fearch of infects or 
roots, as woodcocks ; and others broad ones to filtrate the water 
of lakes, and to retain aquatic infects, as ducks. All which 
feem to have been gradually produced during many generations 
by the perpetual endeavour of the creatures to fupnly the want 
of food, and to have been delivered to their pofterity with conftant 
improvement of them for the purpofes required. 
The third great want amongft animals is that of fecurity, 
which feems much to have diverfified the forms of their bodies 
and the colour of them ; thefe confift in the means ofefcaping 
other animals more powerful than themfelves. Hence fome 
animalshave acquired wings inftead of legs, as the fmaller birds, 
for the purpofe of efcape. Others great length of fin, or of mem- 
brane, as the flying filh, and the bat. Others great fwifmefs 
of Sect. XXXIX. 4. 8. 
GENERATION. 
397 
of foot, as the hare. Others have acquired hard or armed (hells, 
as the tortoife and the echinus matinus. - 
Mr. Ofbeck, a pupil of Linnaeus, mentions the American 
frog-fifh, lophius hiftrio, which inhabits the large floating iflands 
of fca-weed about the Cape of Good Hope, and has fulcra re- 
fembling leaves, that the fifties of prey may miftake it for the 
lea-wee 1, which it inhabits. Voyage to China, p. 113. 
The contrivances for the purpofes of fecurity extend even to 
vegetables, as is feen in the wonderful and various means of 
their concealing or defending their honey from infers, and their 
feeds from birds. On the other hand fwiftnefs of wing has 
been acquired by hawks and fwallows to purfue their prey ; and 
a probofcis of admirable ftructurc has been acquired by the bee, 
the moth, and the humming bird, for the purpofe of plundering 
the netSlaries of flowers. All which feem to have been formed 
by the original living filament, excited into action by the necef- 
fities of the creatures, which poflefs them, and on which their 
exiftence depends. 
From thus meditating on the great flmilarity of the ftruclurc 
of the warm-blooded animals, and at the fame time of the great 
changes they undergo both before and after their nativity ; and 
by confidering in how minute a portion of time many of the 
changes of animals above defcribcd have been produced ; would 
it be too bold to imagine, that in the great length of time, fincc 
the earth began to exift, perhaps millions of ages before the 
commencement of the hiftory of mankind, would it be too bold 
to imagine, that all warm-blooded animals have arifen from one 
living filament, which the great First Cause endued with an- 
imality, with the power of acquiring new parts attended with new 
propenfities, directed by irritations, fenfations,volitions, and affb- 
ciations ; and thus pofl'efiing the faculty of continuing to improve 
by its own inherent activity, and of delivering down thofe im- 
provements by generation to its pofterity, world without end ? 
Sixthly, The cold-blooded animals, as the fifh-tribes, which 
are furniflied with but one ventricle of the heart, and with gills 
inftead of lungs, and with fins inftead of feet or wings, bear a 
great fimilarity to each other ; but they differ, neverthelefs, fo 
much in their general ftruefture from the warm-blooded animals, 
that it may not feem probable at firft view, that the fame living 
filament could have given origin to this kingdom of animals, as 
to the former. Yet are there fome creatures, which unite or 
partake of both thefe orders of animation, as the whales and 
feals ; and more particularly the frog, who changes from an 
aquatic animal furnifhed with gills to an aerial one furnifhed 
with lungs. 
The 398 
GENERATION. 
Sect. XXXIX. 4. 8. 
The numerous tribes of infects without wings, from the fpi- 
der to the fcorpion, from the flea to the lobfler ; or with wings, 
from the gnat and the ant to the wafp and the dragon-fly, dif- 
fer fo totally from each other, and from the red-blooded clafles 
above defcribed, both in the forms of their bodies, and their 
modes of life ; befides the organ of fenfe, which they feem to 
poflefs in their antennae or horns, to which it has been thought 
by fome naturalifts, that other creatures have nothing fimilar ; 
that it can fcarcely be fuppofed that this nation of animals could 
have been produced by the fame kind of living filament, as the 
red-blooded clafles above mentioned. And yet the changes 
which many of them undergo in their early date to that of their 
maturity, are as different, as one animal can be from another. 
As thofe of the gnat, which pafles bis early Rate in water, and 
then ftretching out his new wings, and expanding his new 
Jungs, rifes in the air ; as of the caterpillar, and bee-nymph, 
■which feed on vegetable leaves or farina, and at length burfting 
from their felf-formed graves, become beautiful winged inhab- 
itants of the fkies, journeying from flower to flower, andmounfh- 
cd by the ambrofial food of honey. 
There is ftill another clais of animals, which are termed ver. 
mesby Linnaeus, which are without feet, or brain, and are her- 
maphrodites, as worms, leeches, fnails, fhell-fifh, coralline infects, 
and fponges ; which poflefs the fimplelt llrufture of all animals, 
and appear totally different from thofe already defcribed. The 
fimplicity of their ftrutSlure, however, can afford no argument 
againft their having been produced from a living filament as 
above contended. 
Laft of all the various tribes of vegetables are to be enumera- 
ted amongft the inferior orders of animals. Of thefe the an- 
thers and ffigmas have already been (hewn to poflefs fome organs 
of fenfe, to be nourilhed by honey, and to have the power of 
generation like infects, and have thence been announced amongll 
the animal kingdom in Se£t. XIII. and to thefe muft be added 
the buds and bulbs which conffitute the viviparous offspring of 
vegetation. The former I fuppofe to be beholden to a Angle 
living filament for their feminal or amatorial procreation; and 
the latter to the fame caufe for their lateral or branching gener- 
ation, which they poflefs in common with the polypus, taenia, 
and volvox ; and the fimplicity of which is an argument in fa- 
vour of the fimilarity of its caufe. 
Linnaeus fuppoles, in the Introduction to his Natural Orders, 
that very few vegetables were at firlt created, and that their 
numbers were increafed by their intermarriages, and adds, fua- 
dent ha?c Creatoris leges a fimplicibus ad compofita. Many 
other Sect. XXXIX. 4. 8. 
GENERATION. 
399 
other changes feem to have arifen in them by their perpetual 
eonteft for light and air above ground, and for food or moifture 
beneath the foil. As noted in Botanic Garden, Part II. Note 
on Cufcura. Other changes of vegetables from climate, or 
other caufes, are remarked in the Note on Curcuma in the fame 
work. From thefe one might be led to imagine, that each plant 
at firft confifted of a fmgle bulK or flower to each root, as the 
gentianella and daify ; and that in the eonteft for air and light 
new buds grew on the old decaying flower item, (hooting down 
their elongated roots to the ground, and that in procefs of ages 
tall trees were thus formed, and an individual bulb became a 
fwarm of vegetables. Other plants, which in this eonteft for 
light and air were too flender to rife by their own ftrength, 
learned by degrees to adhere to their neighbours, either by put-* 
ting forth roots like the ivy, or by tendrils like the vine, or by 
fpiral contortions like the honey-fuckle ; or by growing upon 
them like the mifleto, and taking nourilhment from their barks ; 
or by only lodging or adhering on them, and deriving nouriflr- 
nrent from the air, as tillandfia. 
Shall we then fay that the vegetable living filament was orig- 
inally different from that of each tribe of animals above defcri- 
bed ? And that the productive living filament of each of thofe 
tribes was different originally from the other ? Or, as the earth- 
and ocean were probably peopled with vegetable productions 
long before the exiftence of animals ; and many families of thefe 
animals long before other families of them, (hall we conjecture 
that one and the fame kind of living filaments is and has been 
the caufe of all organic life ? 
If this gradual production of the fpecies and genera of animals 
be affented to, a contrary circumftance may be fuppofed to 
have occurred, namely, that fome kinds by the great changes of 
the elements may have been deftroyed. This idea is (hewn to 
our fenfes by contemplating the petrifactions of (hells, and of 
vegetables, which may be laid, Eke bufts and medals, to record 
the hiftory of remote times. Of the myriads of belemnites, cor- 
nua ammonis, and numerous other petrified (hells, which are 
found in the maifes of lime-ftone, which have been produced 
by them, none now are ever found in our feas, or in the feas of 
other parts of the world, according to the obfervations of many 
naturalifts. Some of whom have imagined, that moft of the 
inhabitants of the fea and earth of very remote times are now 
extinCf ; as they fcarcely admit, that a fmgle foffil (hell bears a 
ftriCt fimilitude to any recent ones, and that the vegetable im- 
preflions or petrifadlions found in iron-ores, clay, or fandftone, 
of which there are many of the fern kind, are not fimilar to any 
plants 400 
generation. 
Sect. XXXIX. 4. g. 
plants of this country, nor accurately correfpond with thofe 01 
other climates, which is an argument countenancing the chang- 
es in the forms, both of animals and vegetables, during the pro- 
greflive ftrudture of the globe, which we inhabit. See Town- 
fon's Philo f. of Mineralogy, p. no. 
This idea of the gradual formation and improvement of the 
animal world accords with the obfervations of ibme modern phi- 
lofophers, who have fuppofcd that the continent of America has 
been raifed out of the ocean at a later period of time than the 
other three quarters of the globe, which they deduce from the 
greater comparative heights of its mountains, and the confe- 
quent greater coldnefs of its refpetfive climates, and from the 
lefs fize and flrength of its animals, as the tygers and allegators 
compared with thofe of Afia or Africa. And laftly, from the 
lefs progrefs in the improvements of the mind of its inhabitants 
in refped: to voluntary exertions. 
This idea of the gradual formation and improvement of the 
animal world feems not to have been unknown to the ancient 
philofophers. Plato having probably obferved the reciprocal 
generation of inferior animals, as fnails and worms, was of opin- 
ion, that mankind with all other animals were originally herma- 
phrodites during the infancy of the world, and were in procefs 
of time feparated into male and female. The breafts and 
teats of all male quadrupeds, to which no ufe can be now af- 
figned, adds perhaps fome fhadow of probability to this opinion. 
Linnaeus excepts the horfe from the male quadrupeds, who have 
teats ; which might have fhewn the earlier origin of his exift- 
cnce ; but Mr. J. Hunter afferts, that he has difcovered the vef- 
tiges of them on his fheath, and has at the fame time enriched 
natural hiftory with a very curious fad: concerning the male 
pigeon ; at the time of hatching the eggs both the male and fe- 
male pigeon undergo a great change in their crops ; which thick- 
en and become corrugated, and fecrete a kind of milky fluid, 
which coagulates, and with which alone they for a few days 
feed their young, and afterwards feed them with this coagulated 
fluid mixed with other food. How this refembles the breafts 
of female quadrupeds after the production of their young ! and 
how extraordinary, that the male fhould at this time give milk 
as well as the female 1 See Botanic Garden, Part II. Note on 
Curcuma. 
The late Mr. David Hume, in his pofthumous works, places 
the powers of generation much above thofe of our boafted rea- 
fon ; and adds, that reafon can only make a machine, as a clock 
or aihip, but the power of generation makes the maker of the 
machine; and probably from having obferved, that the grcateft 
put Sect. XXXIX. 5. 1. 
GENERATION. 
401 
part of the earth has been formed out of organic recrements; 
as the immenfe beds of limeftone, chalk, marble, from the fhells 
of fifli; and the extenfive provinces of clay, fandftone, ironftone, 
coals, from decompofed vegetables; all which have been firlt 
produced by generation, or by the fecretions of organic life ; he 
concludes that the world itfelf might have been generated, rath- 
er than created ; that is, it might have been gradually produced 
from very fmall beginnings, increafing by the activity of its in- 
herent principles, rather than by a fudden evolution of the 
whole by the Almighty fiat.-What a magnificent idea of the 
infinite power of the Great Architect ! The Cause of 
Causes I Parent of Parents ! Ens Entium ! 
For if we may compare infinities, it would feem to require a 
greater infinity of power to caufe the caufes of efledis, than to 
caufe the effects themfelves. This idea is analogous to the im- 
proving excellence obfervable in every part of the creation; 
fuch as in the progreflive increafe of the folid or habitable parts 
of the earth from water ; and in the progreflive increafe of the 
wifdom and happinefs of its inhabitants; and is confonant to 
the idea of our prefent fituation being a ftatc of probation, which 
by our exertions we may improve, and are confequently refpon- 
fible for our actions. 
V. i. The efficient caufe of the various colours of the eggs 
of birds, and of the hair and feathers of animals, is a fubjeft fo 
curious, that I fhall beg to introduce it in this place. The 
colours of many animals feem adapted to their purpofes of con- 
cealing themfelves either to avoid danger, or to fpring upon their 
prey. Thus the fnake, and wild cat, and leopard, are fo colour- 
ed as to refemble dark leaves and their lighter interftices; birds 
refemble the colour of the brown ground, or the green hedges, 
which they frequent; and moths and butterflies are coloured 
like the flowers which they rob of their honey. Many inftances 
are mentioned of this kind in Botanic Garden, Part II. Note 
on Rubia. 
Thefe colours have, however, in fome inftances another ufe, 
as the black diverging area from the eyes of the fwan ; which, 
as his eyes are placed lefs prominent than thofe of other birds, 
for the convenience of putting down his head under water, pre- 
vents the rays of light from being reflected into his eyes, and 
thus dazzling his fight, both in air and beneath the water; which 
muft have happened, if that furface had been white like the reft 
of his feathers. 
There is a ftill more wonderful thing concerning thefe colours 
adapted to the purpofe of concealment ; which is, that the eggs 
ofbirds are fo coloured as to referable the colour of the adjacent 
Vol, I. Dod objects 402 
GENERATION. 
Sect. XXXIX. 5. 1, 
objeCts and their interftices. The eggs of hedgebirds are green- 
ifh with dark fpots ; thofe of crows and magpies, which are feen 
from beneath through wicker nefts, are white with dark fpots ; 
and thofe of larks and partridges are ruffet or brown, like their 
nefts or fituations. 
A thing ftill more aftonilhing is, that many animals in coun- 
tries covered with fnow become white in winter, and are faid to 
change their colour again in the warmer months, as bears, hares, 
and partridges. Our domefticated animals lofe their natural 
colours, and break into great variety, as horfes, dogs, pigeons. 
The final caufe of thefe colours is eafily underftood, as they 
ferve fomc purpofes of the animal, but the efficient caufe would 
feem almoft beyond conjecture. 
Firft, the choroid coat of the eye, on which the femitranfpa- 
rent retina is expanded, is of different colour in differnt ani- 
mals ; in thofe which feed on grafs it is green; from hence 
there would appear fome connexion between the colour of the 
choroid coat and of that conftantly painted on the retina by the 
green grafs. Now, when the ground becomes covered with 
fnow, it would feem, that that aCtion of the retina, which is 
called whitenefs, being conftantly excited in the eye, may be 
gradually imitated by the extremities of the nerves of touch, or 
rete mucofum of the fkin. And if it be fuppofed, that the ac- 
tion of the retina in producing the perception of any colour 
confifts in fo difpofing its own fibres or furface, as to reflect 
thofe coloured rays only, and tranfmit the others like foap-bub- 
bles ; then that part of the retina, which gives us the perception 
of fnow, muft at that time be white ; and that which gives us 
the perception of grafs, muft be green. 
Then if by the laws of imitation, as explained in Section XII. 
33. and XXXIX. 6. the extremities of the nerves of touch in 
the rete mucofum be induced into fimilar action, the Ikin or 
feathers, or hair, may in like manner fo difpofe their extreme 
fibres, as to reflect white ; for it is evident, that all thefe parts 
were originally obedient to irritative motions during their 
growth, and probably continue to be fo ; that thofe irritative 
motions are not liable in a healthy ftate to be fucceeded by fen- 
fation ; which however is no uncommon thing in their difeafed 
ftate, or in their infant ftate, as in plica polonica, and in very 
young pen -feathers, which are ftill full of blood. 
It was (hewn in Section XV. on the Production of Ideas, that 
the moving organ of fenfe in fome circumftances refembled the 
objedl which produced that motion. Hence it may be conceiv- 
ed, that the rete mucofum, which is the extremity of the nerves 
of touch, may by imitating the motions of the retina become 
coloured. Sect. XXXIX. 5. 2. 
GENERATION. 
403 
coloured. And thus, like the fable of the chameleon, all ani- 
mals may poflefs a tendency to be coloured fomewhat like the 
colours they moft frequently infpeft, and finally, that colours 
may be thus given to the egg-fhell by the imagination of the fe- 
male parent; which fhell is previoufly a mucous membrane, in- 
dued with irritability, without which it could not circulate its 
fluids, and increafe in its bulk. Nor is this more wonderful than 
that a Angle idea of imagination fliould in an inftant colour the 
whole furface of the body of a bright fcarlet, as in the blufh of 
fhame, though by a very different procefs. In this intricate fub- 
ject nothing but loofe analogical conjectures can be had, which 
may however lead to future difcoveries ; but certain it is that 
both the change of the colour of animals to white in the winters 
of fnowy countries, and the fpots on birds' eggs, mult have fome 
efficient caufe ; fince the uniformity of their production flicws 
it cannot arife from a fortuitous concurrence of circumftances ; 
and how is this efficient caufe to be detected, or explained, but 
from its analogy to other animal facts ? 
2. The nutriment fupplied by the female parent in vivipa- 
rous animals to their young progeny may be divided into three 
kinds, correfponding with the age of the new creature, i. The 
nutriment contained in the ovum as previoufly prepared for the 
embryon in the ovary. 2. The liquor amnii prepared for the 
fetus in the uterus, and in which it fwims ; and laftly, the milk 
prepared in the peCtoral glands for the new-born child. There 
is reafon to conclude that variety of changes may be produced 
in the new animal from all thefe fources of nutriment, but par- 
ticularly from the firft of them. 
The organs of digeftion and of fanguification in adults, and 
afterwards thofe of fecretion, prepare or feparate the particles 
proper for nourilhment from other combinations of matter, or 
recombine them into new kinds of matter, proper to excite into 
aClion the filaments, which abforb or attraCt them by animal ap- 
petency. In this procefs we muft attend not only to the action 
of the living filament which receives a nutritive particle to its 
bofom, but alfo to the kind of particle, in refpect to form, or 
fize, or colour, or hardnefs, which is thus previoufly prepared for 
it by digeftion, fanguification, and fecretion. Now as the firft 
filament of entity cannot be furnilhed with the preparative or- 
gans above mentioned, the nutritive particles, which are at firft 
to be received by it, are prepared by the mother; and depofited 
in the ovum ready for its reception. Thefe nutritive particles 
muft be fuppofed to differ in fome refpedts, when thus prepared 
by different animals. They may differ in fize, folidity, colour, 
and form 5 and yet may be fufficiently congenial to the living 
filament, 404 
GENERATION. 
Sect. XXXIX. 5.2. 
filament, to which they are applied, as to excite its activity by 
their ftimulus, and its animal appetency to receive them, and to 
combine them with itfelf into organization. 
By this firft nutriment thus prepared for the embryon is not 
meant the liquor amnii, which is produced afterwards, nor the 
larger exterior parts of the white of the egg ; but the fluid pre- 
pared, I fuppofe, in the ovary of viviparous animals, and that 
which immediately furrounds the cicatricula of an impregnated 
egg, and is vifible to the eye in a boiled one. 
Now thefe ultimate particles of animal matter prepared by the 
glands of the mother may be fuppofed to,refemble the fimilar 
ultimate particles, which were prepared for her own nourifh- 
ment; that is, to the ultimate particles of which her own or- 
ganization confifts. And that hence when thefe become com- 
bined with a new embryon, which in its early ftate is not fur- 
niflied with ftomach, or glands, to alter them ; that new embry- 
on will bear fome refemblance to the mother. 
This feems to be the origin of the compound forms of mules, 
which evidently partake of both parents, but principally of the 
male parent. In this production of chimeras the ancients feem 
to have indulged their fancies, whence the fphinxes, griffins, 
dragons, centaurs, and minotaurs, which are vanifhed from mod- 
ern credulity. 
It would feem, that in thefe unnatural conjunctions, when the 
nutriment depofited by the female was lb ill adapted to ftimu- 
late the living filament derived from the male into aCtion, and 
to be received, or embraced by it, and combined with it into 
organization, as not to produce the organs neceflary to life, as 
the brain, or heart, or ftomach, that no mule was produced. 
Where all the parts neceflary to life in thefe compound animals 
were formed fufficiently perfeCt, except the parts of generation, 
thofe animals were produced which are now called mules. 
The formation of the organs of fexual generation, in contra- 
diftinCtion to that by lateral buds, in vegetables, and in fome 
animals, as the polypus, the taenia, and the volvox, feems the 
chef d'oeuvre, the mafter-piece of nature; as appears from ma- 
ny flying infcCts, as in moths and butterflies, who feem to un- 
dergo a general change of their forms folely for the purpofe of 
fexual reproduction, and in all other animals this organ is not 
complete till the maturity of the creature. Whence it happens 
that, in the copulation of animals of different fpecics, the parts 
neceflary to life are frequently completely formed ; but thofe 
for the purpofe of generation are defective, as requiring a nicer 
organization ; or more exaCt coincidence of the particles of nu- 
triment to the irritabilities or appetencies of the original living 
filament. Sect. XXXIX. 5.2. 
GENERATION. 
405 
filament. Whereas thofe mules, where all the 'part* tould be 
perfe&ly formed, may have been predated in early periods of 
lime, and may have added to the numbets of our various fpecieS 
of animals, as before obferved. 
As this production of mules is a cohfta'nt effect from the con- 
junction of different fpecies of animats, thofe between the horfe 
and the female afs always refembli'ng the horfe more than the 
afs ; and thofe on the contrary, between the male afs and the 
mare, always relembling the afs more than the mare; it cannot 
be afcribed to the imagination of the male animal which cann'ot 
be fuppofed to operate fo uniformly ; but to the form of the 
firft nutritive particles, and to their peculiar ftirnulus exciting 
the living filament to feleCt and combine them with itfeff. 
There is a fimilar uniformity of effect in refpeCt to the colour 
of the progeny produced between a white man, and a black 
woman, which, if I am well informed, is always of the mulatto 
kind, or a mixture of the two ; which may perhaps be imputed 
to the peculiar form of the particles of nutriment fupplied to 
the embryon by the mother at the early period of its exiltence, 
and their peculiar ftirnulus ; as this effect, like that of the mule 
progeny above treated of, is uniform and confident, and cannot 
therefore be afcribed to the imagination of cither of the parent's. 
Dr. Thunberg obferves, in his Journey to the Cape of Good 
Hope, that there are fome families, which have defeended from 
blacks in the female line for three generations. The firft genera- 
tion proceeding from an European, who married a tawny Have, 
remains tawny, but approaches to a white complexion; but the 
children of the third generation, mixed with Europeans, become 
quite white, and are often remarkably beautiful. Vol. i. p. 111. 
When the embryon has produced a placenta, and furnifhed 
itfelf with veffels for feleftion of nutritious particles, and for 
oxygenation of them, no great change in its form or colour is 
likely to be produced by the particles of fuftenance it now takes 
from the fluid, in which it is immerfed ; becaufe it ha; now ac- 
quired organs to alter or new' combine them. Hence it con- 
tinues to grow whether this fluid, in w'hich it fwims, be formed 
by the uterus or by any other cavity of the body, as in extra- 
uterine geftation ; and wdiich would feem to be produced by 
the ftirnulus of the fetus on the Tides of the cavity, where it is 
found, as mentioned before. And thirdly, there is ftill lefs rea- 
fon to expeeft any unnatural change to happen to the child after 
its birth from the difference of the milk it now takes ; becaufe 
it has acquired a ftomach, and lungs, and glands, of fufficient 
power to decompofe and recombine the milk; and thus to pre- 
pare from it the various kinds of nutritious particles, which the 
appetencies of the various fibrils or nerves may require. 
From 406 
GENERATION. 
Sect. XXXIX. 6. i. 
From all this reafoning I would conclude, that though the 
imagination of the female may be fuppofed to affeCt the embry- 
on by producing a difference in its early nutriment; yet that no 
fuch power can affeCt it after it has obtained a placenta, and 
other organs; which may feleCt or change the food, which is 
prefented to it either in the liquor amnii, or in the milk. Now 
as the eggs in pullets, like the feeds in vegetables, are produced 
gradually, long before they are impregnated, it does not appear 
how any fudden effect of imagination of the mother at the time 
of impregnation can produce any confiderable change in the nu- 
triment already thus laid up for the expected or defired embr /on. 
And that hence any changes of the embryon, except thofe uni- 
form ones in the production of mules and mulattoes, more 
probably depend on the imagination of the male parent. At 
the fame time it feems manifeft, that thofe monftrous births, 
which confift in fome deficiencies only, or fome redundancies 
of parts, originate from the deficiency or redundance of the firft 
nutriment prepared in the ovary, or in the part of the egg im- 
mediately furrounding the cicatricula, as described above ; and 
which continues fome time to excite the firft living filament 
into action, after the fimple animal is completed; or ceafes to 
excite it, before the complete form is accomplifhed. The for- 
mer of thefe circumftances is evinced by the eggs with double 
yolks, which frequently happen to our domefticated poultry, and 
which, I believe, are fo formed before impregnation, but which 
would be well worth attending to, both before and after im- 
pregnation ; as it is probable, fomething valuable on this fubjeft 
might be learnt from them. The latter circumftance, or that 
of deficiency of original nutriment, may be deduced from re- 
verfe analogy. 
There are, however, other kinds of monftrous births, which 
neither depend on deficiency of parts, or fupernumerary ones ; 
nor are owing to the conjunction of animals of different fpecies ; 
but which appear to be new conformations, or new difpofitions 
of parts in refpcCt to each other, and which, like the variation 
of colours and forms of our domefticated animals, and probably 
the fexual parts of all animals, may depend on the imagination 
of the male parent, which we now come to confider. 
VI. i. The nice aClions of the extremities of our various 
glands are exhibited in their various productions, which are be- 
lieved to be made by the gland, and not previoufly to exift as 
fuch in the blood. Thus the glands, which conftitute the liver, 
make bile ; thofe of the ftomach make gaftric acid ; thofe be- 
neath the jaw, faliva ; thofe of the ears, ear-wax ; and the like. 
Every kind of gland muft poffefs a peculiar irritability, and 
probably Sect. XXXIX. 6. 1. 
GENERATION. 
407 
probably a fenfibility, at the early ftate of its exigence ; and 
muft be furnifhed with a nerve of fenfe, or of motion, to per- 
ceive, and to feleCt, and to combine the particles, which com- 
pofe the fluid it fecretes. And this nerve of fenfe which per- 
ceives the different articles which compofe the blood, mult at 
leaft be conceived to be as fine and fubtile an organ, as the op- 
tic or auditory nerve, which perceives light or found. See 
Seft. XIV. 9. 
But in nothing is this nice aClion of the extremities of the 
blood-veflels fo wonderful, as in the production of contagious 
matter. A fmall drop of variolous contagion diffufed in the 
blood, or perhaps only by being inferred beneath the cuticle, 
after a time, (as about a quarter of a lunation,) excites the ex- 
treme veflels of the fkin into certain motions, which produce a 
fimilar contagious material, filling with it a thoufand puftules. 
So that by irritation, or by fenfation in confequence of irrita- 
tion, or by aflbciation of motions, a material is formed by the 
extremities of certain cutaneous veflels, exaClly fimilar to the 
ftimulating material, which caufed the irritation, or confequent 
fenfation, or aflbciation. 
Many glands of the body have their motions, and in confe- 
quence their fecreted fluids, affeCled by pleafurable or painful 
ideas, fince they are in many inftances influenced by fenfitive aflb- 
ciations, as well as by the irritations of the particles of the pafling 
blood. Thus the idea of meat, excited in the minds of hungry 
dogs, by their fenfe of vifion, or of fmell, increafcs the difchargc 
of faliva, both in quantity and vifcidity ; as is feen in its hanging 
down in threads from their mouths, as they ftand round a din- 
ner-table. The fenfations of pleafure, or of pain, of peculiar 
kinds, excite in the fame manner a great difcharge of. tears; 
which appear alfo to be more faline at the time of their fecretion, 
from their inflaming the eyes and eye-lids. The palenefs from 
fear, and the blufh of fhame, and of joy, are other inftances of 
the effects of painful or pleafurable fenfations^ on the extremi- 
ties of the arterial fyflem. 
It is probable, that the pleafurable fenfation excited in the 
ftomach by food, as well as its irritation, contributes to excite 
into aCtion the gaftric glands, and to produce a greater fecre- 
tion of their fluids. The fame probably occurs in the fecretion 
of bile ; that is, that the pleafurable fenfation excited in the 
ftomach, affeCts this fecretion by fenfitive aflbciation, as well as 
by irritative aflbciation. 
And laftly it would fcem, that all the glands in the body 
have their fecreted fluids affeCted, in quantity and quality, by 
the pleafurable or painful fenfations, which produce or accom- 
pany 408 
GENERATION. 
S£ct. XXXIX. 6.* 
pany thofe fecretions. And that the pleafurable fenfations 
arifing from thefe fecretions may conftitute the unnamed pleaf-. 
ure of exiftence, which is contrary to what is meant by taedium 
vita:, or ennui; and by which we fometimes feel ourfelves hap- 
py, without being able to afcribe it to any mental caufe, as af-. 
ter an agreeable meal, or in the beginning of intoxication. 
Now it would appear that no fecrction or excretion of fluid 
is attended with fo much agreeable fenfation, as that of the 
femen ; and it would thence follow, that the glands which per- 
form this fecretion, are more likely to be much affected by their 
catenations with pleafurable fenfations. This circumftance is 
certain, that much more of this fluid is produced in a given 
time, when the object of its exclullon is agreeable to the mind. 
2. A forcible argument, which (hews the neceflity of pleafura- 
blc fenfation. to copulation, is, that the act cannot be performed 
without it.; it is calily interrupted by the pain of fear or bafh- 
fulnefs ; and no. efforts of volition or of irritation can effect 
this.procefs, except fuch as induce pleafurable ideas or fenfa- 
tions. See Se£t. XXXIIE i. i. 
A curious analogical circumftance attending hermaphrodite 
infects, as fnails and worms, dill further iiluftrates this theory ; 
if the fnail or worm could have impregnated itfelf, there might 
have been a faying of a large male apparatus ; but 41s this is 
not fo ordered by nature, but each fnail and worm reciprocally 
receives and gives impregnation, it appears, that a pleafurable 
excitation feems alfo.to have been required. 
This wonderful circumftance of many, infeefts being her- 
maphrodites, and at the fame time not having power to im- 
pregnate themfelves, is attended to by Dr. Lifter, in his Exer- 
citationes. Anatom, de Limacibus, p. 145 ; who, amongft many 
other final caufes, which he adduces to account for it, adds, ut 
tarn triftibus et frigidis animalibus majori cum voluptate perfi- 
ciatur venus. 
There is, however, another final caufe, to which this circum- 
ftance may be imputed : it was obferved above, that vegetable 
buds and bulbs, which are produced without a mother, are al- 
ways exatl reiemblances of their parent; as appears in grafting 
fruit trees, and in the flower-buds of the dioiceous plants, 
which are always of the fame fex on the fame tree ; hence 
thofe hermaphrodite infects, if they could have produced young 
without a mother, would not have been capable of that change 
or improvement, which is feen in all other animals, and in thofe 
vegetables, which are procreated by the male embryon received 
and nourifhed by the female. And it is hence probable, that 
if vegetables could only have been produced by buds and bulbs, 
and Sect. XXXIX. 6. 3. 
GENERATION* 
409 
and not by fexual generation, that there would not at this time 
have exifted one thoufandth part of their prefent number of fpe- 
cies ; which have probably been originally mule-prod unions ; 
nor could any kind of improvement or change have happened 
to them, except by the difference of foil or climate. 
3. I conclude that the imagination of the male at the time 
of copulation, or at the time of the fecretion of the femen, may 
fo affeCI this fecretion by irritative or fenfitive affociation, as 
defcribed in No. V. 1. of this feCtion, as to caufe the produc- 
tion of fimilarity of form and of features, with the diftinCtion 
of fex ; as the motions of the chiflel of the turner imitate or 
correfpond with thofe of the ideas of the artift. It is not here 
to be underftood, that the firft living fibre, which is to form an 
animal, is produced with any fimilarity of form to the future an- 
imal ; but with propenfities, or appetences, which fhall produce 
by accretion of parts the fimilarity of form, feature, or fex, cor- 
refponding to the imagination of the father. 
Our ideas are movements of the nerves of fenfe, as of the 
optic nerve in recollecting vifible ideas, fuppofe of a triangular 
piece of ivory. The fine moving fibres of the retina aCt in a 
manner to which I give the name of white ; and this action is 
confined to a defined part of it; to which figure I give the 
name of triangle. And it is a preceding pleafurable fenfa- 
tion exifting in my mind, which occafions me to pro- 
duce this particular motion of the retina, when no triangle is 
prefent. Now it is probable, that the aCting fibres of the ulti- 
mate terminations of the fecreting apertures of the veflels of 
the teftes, are as fine as thofe of the retina; and that they are 
liable to be thrown into that peculiar aClion, which marks the 
fex of the fecreted embryon, by fympathy with the pleafurable 
motions of the nerves of vifion or of touch; that is, with certain 
ideas of imagination. From hence it would appear, that the 
world has long been miftaken in afcribing great power to the 
imagination of the female, whereas from this account of it, the 
real power of imagination, in the aCt of generation, belongs 
folely to the male. See SeCt. XII. 3-3. 
It may be objected to this theory, that a man may be fuppof- 
ed to have in his mind, the idea of the form and features of the 
female, rather than his own, and therefore there fhould be a 
greater number of female births. On the contrary, the general 
idea of our own form occurs to every one almolt perpetually, 
and is termed confcioufnefs of our existence, and thus may ef- 
fefl, that the number of males furpaffes that of females. See 
SeCL XV. 3. 4. and XVIII. 13. And what further con- 
firms this idea is, that the male chiibren mod frequently 
Vol. I. Etc refemble 410 
GENERATION. 
Sect. XXXIX. 6. 4. 
refemble the father in form, or feature, as well as in fex ; and 
the female molt frequently refemble the mother, in feature, and 
form, as well as in fex. 
It may again be objected, if a female child fometimes refem- 
bles the father, and a male child the mother, the ideas of the 
father, at the time of procreation, muft fuddenly change from 
himfelf to the mother, at the very inftant, when the embryon is 
fecreted or formed. This difficulty ceafes when we confider, 
that it is as eafy to form an idea of feminine features with male 
organs of reproduction, or of male features with female ones, 
as the contrary ; as we conceive the idea of a fphinx or mer- 
maid as eafdy and as diftimftly as of a woman. Add to this, 
that at the time of procreation the idea of the male organs, and 
of the female features, are often both excited at the fame time, 
by contact, or by vifion. 
I alk, in my turn, is the fex of the embryon produced by ac- 
cident ? Certainly whatever is produced has a caufe ; but when 
this caufe is too minute for our comprehenfion, the effect is faid 
in common language to happen by chance, as in throwing a 
certain number on dice. Now what caufe can occafionally pro- 
duce the male or female character of the embryon, but the pe- 
culiar actions of thofe glands, which form the embryon ? And 
what can influence or govern thefe actions of the gland, but its 
affociations or catenations with other fenfitive motions ? Nor is 
this more extraordinary, than that the catenations of irritative 
motions with the apparent vibrations of objects at fea Ihould 
produce ficknefs of the ftomach ; or that a naufeous ftory fhould 
occafion vomiting. 
4. An argument which evinces the effect of imagination on 
the firft rudiment of the embryon, maybe deduced from the 
production of fome peculiar monfters. Such, for inftance, as 
thofe which have two heads joined to one body, and thofe which 
have two bodies joined to one head ; of which frequent exam- 
ples occur amongft our domefticated quadrupeds, and poultry. 
It is abfurd to fuppofe, that fuch forms could exift in primordial 
germes, as explained in No. IV. 4. of this feCtion. Nor is it 
poffible, that fuch deformities could be produced by the growth 
of two embryons, or living filaments; which fhould afterwards 
adhere together ; as the head and tail part of different polypi 
are faid to do (Blumenbach on Generation. Cadell, London); 
iince in that cafe one embryon, or living filament, muft have 
begun to form one part firft, and the other another part 
firft. But fuch monftrous conformations become lefs difficult 
to comprehend, when they are confidered as an effeCt of the im- 
agination, as before explained, on the living filament at the time 
of Sect. XXXIX. 6. 5. 
GENERATION. 
411 
of its fecretion ; and that fuch duplicature of limbs was pro- 
duced by accretion of new parts, in confequence of propenfi- 
ties, or animal appetencies, thus acquired from the male parent 
For inftance, I can conceive, if a turkey-cock fhould behold a 
rabbit, or a frog, at the time of procreation, that it might hap- 
pen, that a forcible or even a pleafurable idea of the form of a 
quadruped might fo occupy his imagination, as to caufe a tenden- 
cy in the nafcent filament to refemble fuch a form, by the appo- 
rtion of a duplicature of limbs. Experiments on the production 
of mules and monfters would be worthy the attention of a Spal- 
lanzani, and might throw much light upon the fubjed, which 
at prefent muft be explained by conjectural analogies. 
The wonderful effect of imagination, both in the male and 
female parent, is (hewn in the production of a kind of milk in 
the crops both of the male and female pigeons after the birth of 
their young, as obferved by Mr. Hunter, and mentioned before. 
To this fhould be added, that there are fome infiances of men 
having had milk fecreted in their breafts, and who have given 
fuck to children, as recorded by Mr. Buffon. This effeCt 
of imagination, of both the male and female parent, feems to 
have been attended to in very early times ; Jacob is faid not on- 
ly to have placed rods of trees, in part ftripped of their bark, fo 
as to appear fpotted, but alfo to have placed fpotted lambs before 
the flocks, at the time of their copulation. Genelis, chap. xxx. 
verfe 40. 
5. In refpeCl to the imagination of the mother, it is diffi- 
cult to comprehend, how this can produce any alteration in the 
fetus, except by affeCting the nutriment laid up for its firfl re- 
ception, as defcribed in No. V. 2. of this feClion, or by afl'ed- 
ing the nourifhment or oxygenation with which fhe fupplies it 
afterwards. Perpetual anxiety may probably affeCl the fecre- 
tion of the liquor amnii into the uterus, as it enfeebles the 
whole fyftem ; and fudden fear is a frequent caufe of mifcar- 
riage ; for fear, contrary to joy, decreafes for a time the aftion 
of the extremities of the arterial fyflem ; hence fudden pale- 
nefs fucceeds, and a fhrinking or contraCiion of the veflels of 
the fkin, and other membranes. By this circumflance, I im- 
agine, the terminations of the placental veflels are detached 
from their adhefions, or infertions, into the membrane of the 
uterus ; and the death of the child fucceeds, and confequent 
mifcarriage. 
Of this I recoiled a remarkable inftance, which could be af- 
cribed to no other caufe, and which I fhall therefore relate in 
few words. A healthy young woman, about twenty years of 
age, had been about five months pregnant, and going down in- 
to 412 
GENERATION. 
Sect. XXXIX. 6.6. 
to her cellar to draw fome beer, was frighted by a forvant boy 
Harting up from behind the barrel, where he had concealed 
himfclf with defign to alarm the maid-fervant, for whom he 
millook his miftrefs. She came with difficulty up flairs, began 
to flood immediately, and mifcarried in a few hours. She has 
fince borne feveral children, nor ever had any tendency to mif- 
carry of any of them. 
In refpefl to the power of the imagination of the male over 
the form, colour, and fex of the progeny, the following in- 
llances have fallen under my obfervation, and may perhaps be 
found not very unfrequent, if they were more attended to. I 
am acquainted with a gentleman, who has one child with dark 
hair and eyes ; though his lady and himfelf have light hair 
and eyes ; and their other four children are like their parents. 
On obferving this diffimilarity of one child to the others he 
affured me, that he believed it was his own imagination, that 
produced the difference ; and related to me the following ftory. 
He faid, that when his lady lay in of her third child, he became 
attached to a daughter of one of his inferior tenants, and offer- 
ed her a bribe for her favours in vain ; and afterwards a greater 
bribe, and was equally unfuccefsful; that the form of this girl 
dwelt much in his mind for fome weeks, and that the next child, 
which was the dark-eyed young lady above mentioned, was ex- 
ceedingly like, in both features and colour, to the young woman 
who refufed his addreffes. 
To this inftance I mull add, that I have known two families, 
in which, on account of an intailed eftate in expectation, a male 
heir was molt eagerly defired by the father; and on the con- 
trary, girls were produced to the feventh in one, and to the ninth 
in another; and then they had each of them a fon. I conclude, 
that the great defire of a male heir by the father produced rath- 
er a difagreeable than an agreeable fenfation ; and that his ideas 
dwelt more on the fear of generating a female, than on the pleaf- 
urable fenfations or ideas of his own male form or organs at the 
time of copulation, or of the fecretion of the femen ; and that 
hence the idea of the female character was more prefent to his 
mind than that of the male one ; till at length indefpair of gen- 
erating a male thefe ideas ceafed, and thofe of the male charac- 
ter prefided at the genial hour. 
6. Hence I conclude, that the aft of generation cannot ex- 
ill without being accompanied with ideas, and that a man mull 
have at that time either a general idea of his own male form, or 
of the form of his male organs ; or an idea of the female form, 
or of her organs ; and that this marks the fex, and the peculiar 
refemblances of the child to either parent. From whence it 
would Sect. XXXIX. 7. 1. 
GENERATION. 
413 
would appear, that the phalli, which were hung round the necks 
of the Roman ladies, or worn in their hair, might have effedt 
in producing a greater proportion of male children ; and that 
the calipredia, or art of begetting beautiful children, and of pro- 
creating either males or females, may be taught by aftedling the 
imagination of the male-parent ; that is, by the fine extremities 
of the feminal glands imitating the actions of the organs of fenfe 
either of fight or touch. But the manner of aocomplifhing this 
cannot be unfolded with fuflicient delicacy for the public eye ; 
but may be worth the attention of thofe, who are ferioufly in- 
terefted in the procreation of a male or female child. 
Recapitulation. 
VII. i. A certain quantity of nutritive particles are produ- 
ced by the female parent before impregnation, which require 
no further digeftion, fecretion, or oxygenation. Such are feen 
in the unimpregnated eggs of birds, and in the unimpregnated 
feed-veffels of vegetables. 
2. A living filament is produced by the male, which being 
inferted amidft thefe firft nutritive particles, is ftimulated into 
action by them ; and in confequence of this action, fome of the 
nutritive particles are embraced, and added to the original liv- 
ing filament; in the fame manner as common nutrition is per- 
formed in the adult animal. 
3. Then this new organization, or additional part, becomes 
flimulated by the nutritive particles in its vicinity, and fenfation 
is now fuperadded to irritation ; and other particles are in con- 
fequence embraced, and added to the living filament; as is feen 
in the new granulations of flefh in ulcers. 
By the power of aiTociation, or by irritation, the parts already 
produced continue their motions, and new ones are added by 
fcnfation, as above mentioned ; and laftly by volition, which 
laft fenforial power is proved to exift in the fetus in its maturer 
age, becaufe it has evidently periods of activity and of fleeping ; 
which laft is another word for a temporary fufpenfion of volition. 
The original living filament may be conceived to poffefs a 
power of repulfing the particles applied to certain parts of it, as 
well as of embracing others, which ftimulate other parts of it ; 
as thefe powers exift in different parts of the mature animal ; 
thus the mouth of every gland embraces the particles or fluid, 
which fuit its appetency ; and its excretory du<St repulfes thole 
particles, which are difagreeable to it. 
4. Thus the outline or miniature of the new animal is pro- 
duced gradually, but in no great length of time •, becaufe the 
original 414 
GENERATION. 
Sect. XXXIX. 7. 5. 
original nutritive particles require no previous preparation by di- 
geftion, fecretion, and oxygenation : but require limply the fe- 
leCtion and apportion, which is performed by the living fila- 
ment. Mr. Blumenbach fays, that he poflefles a human fetus of 
only five weeks old, which is the fize of a common bee, and 
has all the features of the face, every finger, and every toe com- 
plete ; and in which the organs of generation are diftin&ly feen. 
P. 76. In another fetus, whofe head was not larger than a pea, 
the whole of the bafis of the fkull with all its depreflions, aper- 
tures, and procefles, were marked in the molt fharp and diftinCt 
manner, though without any oflification. Ib. 
5. In fome cafes by the nutriment originally depofited by the 
mother the filament acquires parts not exactly fimilar to thofe 
of the father, as in the production of mules and mulattoes. In 
other cafes, the deficiency of this original nutriment caufes defi- 
ciencies of the extreme parts of the fetus, which are laft form- 
ed, as the fingers, toes, lips. In other cafes, a duplicature of 
limbs, is caufed by the fuperabundance of this original nutritive 
fluid, as in the double yolks of eggs, and the chickens from 
them with four legs and four wings. But the production of 
other monfters, as thofe with two heads, or with parts placed in 
wrong fituations, feems to arife from the imagination of the 
father being in fome manner imitated by the extreme veflels of 
the feminal glands ; as the colours of the fpots on eggs, and the 
change of the colour of the hair and feathers of animals by do- 
meftication, may be caufed in the fame manner by the imagina- 
tion of the mother. 
6. The living filament is a part of the father, and has there- 
fore certain propenfities, or appetencies, which belong to him; 
which may have been gradually acquired during a million of 
generations, even from the infancy of the habitable earth ; and 
which now poflefles fuch properties, as would render, by the 
appofition of nutritious particles, the new fetus exactly fimilar 
to the father ; as occurs in the buds and bulbs of vegetables, 
ami in the polypus, and ttenia, or tape-worm. But as the firft 
nutriment is fupplied by the mother, and therefore refembles fuch 
nutritive particles, as have been ufed for her own nutriment or 
growth, the progeny takes in part the likenefs of the mother. 
Other fimilarities of the excitability, or of the form of the male 
parent, fuch as the broad or narrow (boulders, or fuch as con- 
ftitute certain hereditary difeafes, as fcrofula, epilepfy, infanity, 
have their origin produced in one or perhaps two generations ; 
as in the progeny of thofe who drink much vinous fpirits ; and 
thofe hereditary propenfities ceafe again, as I have obferved, if 
one or two fober generations fucceed ; otherwife the family 
becomes extimft. This Sect. XXXIX. 7. 7. 
GENERATION. 
415 
This living filament from the father is alfo liable to have its 
propenfities, or appetencies, altered at the time of its production 
by the imagination of the male parent ; the extremities of the 
feminal glands imitating the motions of the organs of fenfe ; 
and thus the fex of the embryon is produced ; which may be 
thus made a male or a female by affeCiing the imagination of 
the father at the time of impregnation. See SeCt. XXXIX. 6. 
3. and 7. 
7. After the fetus is thus completely formed together with 
its umbilical veflels and placenta, it is now fupplied with a dif- 
ferent kind of food, as appears by the difference of confiftency 
of the different parts of the white of the egg, and of the liquor 
amnii, for it has now acquired organs for digeftion or fecretion, 
and for oxygenation, though they are as yet feeble ; which can 
in fome degree change, as well as feleCt the nutritive particles, 
which are now prefented to it. But may yet be affeCted by the 
deficiency of the quantity of nutrition fupplied by the mother, 
or by the degree of oxygenation fupplied to its placenta by the 
maternal blood. 
The augmentation of the complete fetus by additional particles 
of nutriment is not accomplifhed by diftention only, but by ap- 
pofition to every part both external and internal; each of which 
acquires by animal appetencies the new addition of the particles 
which it wants. And hence the enlarged parts are kept fimilar 
to their prototypes, and may be faid to be extended ; but their 
extenfion muft be conceived only as a neceffary confequence of 
the enlargement of all their parts by appofition of new particles. 
Hence the new appofition of parts is not produced by capilla- 
ry attraction, becaufe the whole is extended; whereas capillary 
attraction would rather tend to bring the fides of flexible tubes 
together, and not to diftend them. Nor is it produced by 
chemical affinities, for then a folution of continuity would fuc- 
ceed, as when fugar is diflblved in water ; but it is produced by 
an animal procefs, which is the confequence of irritation, or 
fenfation ; and which may be termed animal appetency. 
This is further evinced from experiments, which have been 
inflituted to fhew, that a living mufcle of an animal body re- 
quires greater force to break it, than a fimilar mufcle of a dead 
body. Which evinces, that befides the attraction of cohefion, 
which all matter poiTefTes, and befides the chemical attractions 
of affinities, which hold many bodies together, there is an ani- 
mal adhefion, which adds vigour to thefe common laws of the 
inanimate world. 
8. At the nativity of the child it depofits the placenta or 
gills, and by expanding its lungs acquires more plentiful oxyge- 
nation 416 
GENERATION. 
Sect. XXXIX. 7.9. 
nation from the currents of air, which it mull now continue 
perpetually to refpire to the end of its life ; as it now quits the 
liquid element, in which it was produced, and like the tadpole, 
when it changes into a frog, becomes an aerial animal. 
9. As the habitable parts of the earth have been, and con- 
tinue to be, perpetually increafing by the production of fea- 
fhells and corallines, and by the recrements of other animals, 
and vegetables ; fo from the beginning of the exiftence of this 
terraqueous globe, the animals, which inhabit it, have conftant- 
ly improved, and are {till in a ftate of progrelfive improvement. 
This idea of the gradual generation of all things feems to 
have been as familiar to the ancient philofophers as to the mod- 
ern ones; and to have given rife to the beautiful hieroglyphic 
figure of the uav, or firft great egg, produced by night, 
that is, whofe origin is involved in obfeurity, and animated by 
that is, by Divine Love ; from whence proceeded all things 
which exift. 
appendix. 
VIII. 1. Since the former publication of the preceding Sec- 
tion on Generation, I have been induced in my treatife on Phyt- 
ologia, to give more attention to the lateral or folitary genera- 
tion of vegetables in the production of their buds, hoping from 
thence to throw fome light on their fexual generation in the pro- 
duction of feeds ; and in confequence on the propogation of 
more perfect animals, which I fhall here relate, believing that 
it may intereft the philofophical reader, obferving only, that by 
the vegetable facts here attended to, I am now induced to be- 
lieve, that the embryons of complicate animal and vegetable 
bodies are not formed from a fingle filament as above delivered ; 
but that their ftructure commences in many parts at the fame 
time, though it is probable, that the inoft fimple or firlt exordi- 
um of animation was begun by a fingle filament, and continues 
to do fo in the fpontaneous production of the fmalleft micro- 
fcopic animals, which do not appear to have been generated 
by other animalcula fimilar to themfelves, as further fpoken of 
in No. ii. 5. of this Section. 
1. It is fnewn at large in the work above mentioned, that 
every bud of a tree is an individual vegetable, and confifts of the 
plumula or leaf at its fummit, of a long caudex extending from 
this fummit downwards to the earth, forming a filament of the 
bark, and laftly of radicles beneath the foil : it is alfo (hewn, 
that every bud poflefies the power of germination or reproduc- 
tion, not only in the axilla of the leaf, which is molt common, 
but Sect. XXXIX. 8. 1. 
GENERATION. 
417 
but from any part of the long caudex gemmse above mentioned, 
as appears from new buds Springing out from any part of the 
bark, when the top of a branch is cut off. 
Now if a feion of a nonpareil apple be ingrafted on a crab 
ftock, and a 'golden-pippin be ingrafted on the nonpareil, what 
happens ?-The caudex of the bud of the golden-pippin confifts 
of its proper abforbent veflels, arteries, and veins, till it reaches 
down to the nonpareil ftock ; and then the continuation of its 
caudex downwards confilts of veflels fimilar to thofe of the non- 
pareil ; and when its caudex defeends ftill lower, it confifts of 
veflels fimilar to thofe of the crab-flock. 
The truth of this is (hewn by two circumflances ; firft, be- 
caufe the lower parts of this compound tree will occafionally put 
forth buds fimilar to the original flock. And fecondly, be- 
caufe in fome ingrafted trees, where a quick-growing feion 
has been inferted into a ftock of flower growth, as is often feen 
in old cherry-trees, the upper part of the trunk of the tree has 
become of almoft double the diameter of the lower part. Both 
which occurrences fhew, that the lower part of the trunk of the 
tree continues to be of the fame kind, though it muft have been 
fo repeatedly covered over with new circles of wood, bark, and 
cuticle. » 
Now as the caudex of each bud, which pafles the whole 
length of the trunk of the tree, and forms a communication from 
the upper part or plumula, to the lower part or radicle, muft 
confift in thefe doubly ingrafted trees of three different kinds of 
caudexes, refembling thofe of the different flocks or feions ; we 
acquire a knowledge of what may be termed a lateral or pater- 
nal mule, in contradiftinflion to a fexual mule. For as in thefe 
trees thus combined by ingraftment every bud has the upper 
part of its caudex that of a golden-pippin, the middle part of it 
that of a nonpareil, and^he lower part of it that of a crab; if 
thefe caudexes, which conftitute the filaments of the bark could 
be feparated intire from the tree with their plumules and radi- 
cles, they would exhibit fo many lateral or paternal mules, con- 
fifting of the connected parts of their three parents ; the plu- 
mula belonging to the upper parent, and the radicle to the low- 
er one, and the triple caudex to them all. 
A feparation of thefe buds from the parent plant is faid to 
have been obferved by Mr. Blumenbach, in the conferva fonti- 
nalis, a vegetable which confifts of finall fhort {lender threads, 
which grow in our fountains, and fix their roots in the mud. 
He obferved by magnifying glafles, that the extremities of the. 
threads fwell, and form finall tubcra or heads ; which gradually 
feparate from the parent threads, attach themfelvcs to the 
Vol. I. ,F f f ground, 418 
GENERATION. 
Sect. XXXIX. 8. 2. 
ground, and become perfect vegetables ; the whole progrefs of 
their formation can be obferved in forty-eight hours. Obfer- 
vations on plants by Von Uflar. Creech, Edinb. 
2. The lateral propagation of the polypus found in our ditches 
in July, but more particularly that of the hydra ftentorea, is won- 
derfully analogous to the above idea of the lateral generation of 
vegetables. The hydra ftentorea, according to the account of 
hlonf. Trembley, multiplies itfelf by fplitting lengthwife ; and 
in twenty-four hours thefe divifions, which adhere to a common 
pedicle, refplit, and form four diftindt animals. Thefe four in 
an equal time fplit again, and thus double their number daily ; 
till they acquire a figure fomewhat refembling a nofegay. The 
young animals afterwards feparate from the parent, attach them- 
felves to aquatic plants, and give rife to new colonies. 
Another curious animal fact is related by Blumenbach in his 
Treatife on Generation concerning the frefh water polypus. He 
cut two of them in halves, which were of different colours, and 
applying the upper part of one to the lower part of the other by 
means of a glafs tube, and retaining them thus for feme time in 
contact with each other, the two divided extremities united, and 
became one animal. The facil union of the divided halves of 
different polypi is alfo afferted by Mr. Adams. Treatife on 
Microfcopes. 
The intelligent reader has already anticipated me in applying 
thefe wonderful modes of lateral animal reproduction and con- 
junction, to the lateral propagation and ingraftment of vegeta- 
bles. The junction of the head part of one polypus to the tail- 
part of another is exactly reprefented by the ingraftment of a 
feion on the flock of another tree, the plumula or apex of each 
bud with the upper part of its caudex joins to the long caudex 
of the Hock, which palling down the trunk terminates in the 
radicles of it. And if this compound vegetable could be fepa- 
rated longitudinally from the other long filaments of the bark in 
its vicinity, like the fibres of the bark of the mulberry tree pre- 
pared at Otaheite, or as the bark of hemp and flax are pre- 
pared in this country, as the young ones of the hydra ftentorea 
Separate from their parents, it might claim the name of a lateral 
or paternal mule, as above mentioned. 
3. It hence appears, that every new bud of a tree, where two 
feions have been inferted over each other on a Hock, if it could 
be feparated from the plume to the radicle, mult confift of three 
different kinds of caudex ; and might therefore be called a triple 
Literal mule. And that hence it follows, that every part of this 
new triple caudex muff have been feparated or fecrcted laterally 
from the adjoining part of the trunk of the tree ; and that it 
could Sect. XXXIX. 8. 4. 
GENERATION. 
419 
'could not be formed, as I formerly believed, from the roots of 
the plume of the bud defcending from the upper part of the cau- 
dex of it to the earth. A circumftance of great importance in 
the inveftigation of the curious fubjett of the lateral generation 
of vegetables, and of infers. 
One might hence fufpect, that if Blumenbach had attended to 
the propagation of the polypus, which he had compofed of two 
half polypi, that the young progeny might have poffeffed two 
colours refembling the compound parent, like the different cau- 
dexes of ingrafted trees ; an experiment well worthy repeated 
obfervation. 
4. Another animal faft ought alfo to be here mentioned, 
that many infefts, as common earth worms as well as the poly- 
pus, are faid to poffefs fo much life throughout a great part of 
their fyftem ; that they may be cut into two or more pieces 
without deftroying them ; as each piece will acquire a new head, 
or a new tail, or both, and the infefl will thus become multi- 
plied ! How exactly this is refembled by the long caudex of the 
buds of trees ; which poffefs fuch vegetable life from one ex- 
tremity to the other, that when the head or plume is lopped off, 
it can produce a new plume, and when the lower part is cut 
off, it can produce new radicles; and may be thus wonderfully 
multiplied ! 
This curious vegetable phenomenon is worthy our attention 
and remembrance ; for as each filament of the new bark of a 
tree conftitutes a caudex of an embryon bud ; when the fum- 
mit of a twig is lopped off, which contained the plumules or em- 
bryon leaves of many of them ; each embryon caudex can gen- 
erate new plumules or embryon leaves; and new radicles, when 
the lower part of a twig is cut off, and the upper part planted ; 
which demonftrates, that the primary parts of a vegetable em- 
bryon may produce fecondary parts ; and that hence it is not 
neceffary, that the whole of an animal fetus Ihould be formed 
at the fame time. 
5. Hence we acquire fome new and important ideas con- 
cerning the lateral generation of vegetables, and which may 
probably contribute to elucidate their fexual generation. Thefe 
are, firft, that the parts of the long caudex of each new bud of 
an ingrafted tree, and confequently of all trees, are feparated 
or fecreted from the correfpondent or adjoining parts of the 
long caudex of the laft year's bud, which was its parent. And 
not that it confifts of the roots of each new bud fhot down from 
the plumula or apex of it ; as I formerly fuppofed. And that 
thefe various molecules or fibrils fecreted from the caudex of 
the laft year's buds adjoin and grow together beneath the cuticle 
of 420 
GENERATION. 
Sect. XXXIX. 8. 6. 
of the trunk of the tree ; the upper ones forming the plumula 
of the new bud, which is its leaf or lungs to acquire oxygen 
from the atmofphcre ; and the lower ones forming the radicles 
of it, which are abforbent veffels to acquire nutriment from 
the earth. 
Secondly, that every part of the caudex of an ingrafted tree, 
and confequently of all trees, can generate or produce a new 
plumula, when the upper part of it is ftrangulated with a wire 
or cut off; or otherwife when it is fupplied more abundantly 
with nutriment, ventilation, and light. And that each of thefe 
new buds thus produced refembles that part of the Itock in com- 
pound trees, where it arifes. Thus in the triple tree above 
mentioned a bud from the upper part of the long caudexes, 
which form the filaments of the bark, Would become a golden- 
pippin branch, a bud from the middle part of them would 
become a nonpareil branch, and a bud from the lower part a 
crab branch. 
Thirdly, another wonderful property of this lateral mule 
progeny of trees compounded by ingraftment confifts in this, 
that the new mule may confift of parts from three or four or 
many parents ; when fo many different fcions are ingrafted on 
each other, whence a queftion may arife, whether a mixture of 
two kinds of anther-duff previous to its application to the ftigma 
of flowers might not produce a threefold mule partaking of the 
likenefs of both the males ? 
6. On this nice fubjeft of reprodu&ion, fo far removed from 
common apprehenfion, the patient reader will excufe a more 
prolix investigation. The attraction of all matter to the centres 
of the planets, or of the fun, is termed gravitation, that of par- 
ticular bodies to each other is generally called chemical affinity ; 
to which the attractions belonging to eleCtricity and magnetifm 
appear to be allied. 
In thefe latter kinds of attraction two circumflances feem to 
be required, firft, the power to attraCt poffefled by one of the 
bodies, and fecondly, the aptitude to be attraded poffefled by 
the other. Thus when a magnet attracts iron, it may be faid 
to poflefs a fpecific tendency to unite with iron ; and the iron 
may be faid to poflefs' a fpecific aptitude to be united with the 
magnet. The former appears to refide in the magnet, becaufe 
it can be deprived of its attractive power, which can alfo be reftor- 
ed to it. And the iron appears to poflefs a fpecific aptitude to be 
united with the magnet, becaufe no other metal will approach 
it. In the fame manner a rubbed glafs tube or a rubbed ffick 
of fealing wax may be faid to poflefs a fpecific tendency to unite 
with a light flraw, or hair, and the flraw or hair to poflefs a 
fpecific Sect. XXXIX. 8. 7. 
GENERATION. 
421 
fpecific aptitude to unite with the rubbed glafs or fealing wax; 
becaufe the fpecific attraction to the rubbed glafs or fealing wax 
can be withdrawn or reftored; to which maybe added, that 
fome chemical combinations may arife from the fingle attrac- 
tion of one body, and the aptitude to be attracted of another. 
Or they may be owing to reciprocal attractions of the two 
bodies, as in what is termed by the chemifts double affinity, 
which is known to be fo powerful as to feparate thofe bodies, 
which are held together by the fimple attraction probably of 
one of them to the other; which other poflefles only an apti- 
tude to be attracted by the former. 
It is probable, that in fome of the mod fimple combinations 
of the particles of inanimate matter, two of them may be 
flrongly united by reciprocal attractions to each other ; that in 
other fimple combinations two particles may be held together, 
though lefs firmly, by the attraction of one and the aptitude to be 
attracted of the other. Thus I fufpeCt that carbon and oxygen ruflt 
together by their reciprocal attractions producing explofion, and 
being afterwards not eafily feparable ; while azote or nitrogen is 
lefs firmly united with oxygen by the attraction of one of them, 
and only the aptitude to be attracted of the other. If this cir- 
cumftance could be nicely afcertained, the theory of chemical 
affinities might poffibly advance a ftep further in the explana- 
tion of fome difficult phenomena, as of the heat generated in 
the explofion df various materials, with which oxygen is more 
loofely united, when applied to ignited carbon ; as of the acid 
of nitre, and feveral metallic oxydes ; as well as of the general 
circumftances of combuition and inflammation, as of p'hofpho- 
rus in the atmofphere, and of oil of cloves with nitrous acid. 
7. The above account of the tendencies to union of unor- 
ganized or inanimate matter is not given as a philofophical 
analogy, but to facilitate our conception of the adjunctions or 
concretions obfervable in organized or animated bodies ; which 
conftitute their formation, their nutrition, and their growth. 
Thefe may be divided into two kinds •, firft the junction or 
union of animated bodies with inanimate matter, as when fruit 
or flefh is fwallowed into the ftomach, and becomes abforbed 
by the ladeals; and the fecond, where living particles coalefce or 
concrete together ; as in the formation, nutrition, or conjunc- 
tion of the parts of living animals. 
In refpect to the former the animal parts, as the noftrils and 
palate, poflefs an appetency, when ftimulated by the feent and 
flavour of agreeable food, to unite themfelves with it; and the 
inanimate material poffefl'es an aptitude to be thus united with 
the animal organ. The fame occurs, when the food is fwal- 
lowed 422 
GENERATION. 
Sect. XXXIX. 8. 8. 
lowed into the ftomach ; the mouths of the laCteal veflels be- 
ing agreeably ilimulatcd pofl'efs an appetency to abforb the par- 
ticles of the digefting mafs ; which is in a fituation of under- 
going chemical changes, and poflefles at fome period of them 
an aptitude to flimulate, and to be united with the mouths of 
the abforbent laCteals. 
But when thefe abforbed particles of inanimate matter have 
been circulated in the blood, they feem gradually to obtain a 
kind of vitality ; whence Mr. John Hunter, and I believe fome 
antient philofophers, and the divine Mofes, aflerted, that the 
blood is alive ; that is, that it poflefles fome degree of organi- 
zation, or other properties, different from thole of inanimate 
matter ; which are not producible by any chemical procefs, and 
which ceafe to exift along with the life of the animal. Hence 
for the purpofe of nutrition there is reafon to fufpeCt, that two 
circumftances are necefl'ary, both dependent upon life, and con- 
fequent activity ; thefe are firfl: an appetency of the fibrils of 
the fixed organization, which wants nutrition ; and fecondly a 
propenfity of the fluid molecules exifting in the blood, or fe- 
creted from it, to unite with the organ now flimulated into ac- 
tion. So that nutrition may be faid to be effected by the em- 
brace or coalefcence of the fibrils, which pofl'efs nutritive appe- 
tencies, with the molecules, which pofl'efs nutritive propenfities, 
or in other words of particles, which pofl'efs reciprocal appeten- 
cies to embrace each other. 
8. If the philofopher, who thinks on this fubjedt, fhould not 
be inclined to believe, that the whole of the blood is alive, he 
cannot eafily deny life to that part of it, which is fecreted by 
the organs of generation, and conveys vitality to the new em- 
bryon, which it produces. Hence though in the procefs of nu- 
trition the activity of two kinds of fibrils or molecules may be 
fufpedted, yet in the procefs of the generation of a new vegeta- 
ble or animal, there feems great reafon to believe, that both the 
combining and combined particles are endued with vitality ; 
that is, with fome degree of organization or other properties not 
exifting in inanimate matter, which we beg leave to denom- 
inate fibrils with formative appetencies, and molecules with 
formative propenfities ; as the former may feem to pofl'efs a 
greater degree of organization than the latter. 
And thus it appears, that though nutrition may be conceived 
to be produced by the animated fibrils of an organized part be- 
ing ftimulated into aCtion by inanimate molecules, which they 
then embrace ; and may thus be popularly compared to the 
fimple attractions of chemiftry ; yet that in the production of 
a new embryon, whether vegetable or animal, both the fibrils 
with Sect. XXXIX. 8. 9. 
GENERATION. 
423 
with formative appetencies and the molecules with formative pro- 
penfities reciprocally ftimulate-and embrace each other, and in- 
ffantly coalefce; and may thus popularly be compared to the recip- 
rocal attractions of fome of the atoms of inanimate matter, or to 
the double affinities of chemiltry. But there are animal fads, 
which may be compared to both thefe, and are thence more 
philofophically analagous to them ; and thefe are the two great 
fupports of animated nature, the paffions of hunger of and love. 
In the former the appetency refides only in the ftomach, or per- 
haps in the cardia ventriculi, but the objeCt confifts of inani- 
mate matter ; in the latter there exift reciprocal appetencies 
and propenfities in the male and female, which mutually ex- 
cite them to embrace each other. Two other animal faCts are 
equally analogous ; the thirft, which refides at the upper end 
of the efophagus, and though it poffeffes appetency itfelf, its ob- 
je£t is inanimate matters ; but in laClefcent females, when they 
give fuck to their young, there exifts a reciprocal appetency in 
the mother to part with her milk, and in the young offspring to 
receive it. 
This then finally I conceive to be the manner of the produc- 
tion of the lateral progeny of vegetables. The long caudex of 
an exifting bud of a tree, which conftitutes a fingle filament of 
the prefent bark, is furniffied with glands numerous as the perfpi- 
rative or mucous glands of animal bodies ; and that thefe are of 
two kinds, the one fecreting from the vegetable blood the fibrils 
with formative appetencies, correfpondent to the mafeuline fe- 
cretion of animals ; and the other fecreting from the vegetable 
blood the molecules with formative propenfities, correfpon- 
dent to the feminine fecretion of animals, and then that both 
thefe kinds of formative particles are depofited beneath the cu- 
ticle of the bark along the uffiole courfe of it, and inllantly em- 
brace and coalefce, forming a new caudex along the fide of its 
parent, with vegetable life, and with the additional powers of 
nutrition, and of growth. 
9. This then is the great fecret of nature. More living 
particles, fome with appetencies, and fome with propenfities, 
are produced by the powers of vitality in the fabrication of the 
vegetable blood, than are neceffary for nutrition, or for the ref- 
toration of decompofing organs. Thefe are fecreted by differ- 
ent glands, and detruded externally, and produce by their com- 
bination a new vital organization beneath the cuticles of trees 
over the old one. Thefe new combinations of vital fibrils and 
molecules acquire new appetencies, and fabricate molecules 
with new propenfities ; and thus poffefs the power of forming 
the leaf or lungs at one extremity of the new caudex 5 and the 
radicles 424 
GENERATION. 
Sect. XXXIX. 8.1©. 
radicles or abforbent veffels at the other end ; and Tome of them, 
as in the central buds, which terminate the branches, finally 
form the fexual organs of reproduction, which conftitute the 
flower ; all which are fecondary parts of the new embryon or 
fetus, as (hewn in number 9. 4. of this feCiion. 
That new organizations of the growing fyftem acquire new 
appetencies appears from the production of the paffion for gen- 
eration, as foon as the adapted organs are complete, and alfo 
from the variation of the palate, or defire for particular kinds 
of food, as we advance in life, as from milk to flelh ; thus as a 
popular allufion, not as a philofophical analogy, we may again 
be allowed to apply to the combinations of chemiftry. Where 
two different kinds of particles unite, as acids and alkalies, a 
third fomething is produced, which poffeffes attractions diflimi- 
lar to thofe of either of them. 
And that new organizations form new molecules, appears 
from the fecretions of the feminal and uterine glands, when 
they have acquired their maturity ; and from the peCloral ones 
of ladefcent females. 
10. In the lateral propagation of vegetable buds, as the fu- 
perfluous fibrils or molecules, which were fabricated in the 
blood, or detached from living organs, and poffefs nutritive or 
formative appetencies and propenfities ; and which were more 
abundant, than were required for the nutrition of the parent 
vegetable bud, when it had obtained its full growth, were fe- 
creted by innumerable glands on the various parts of its furface 
beneath the general cuticle of the tree, and there embracing and 
coalefcing, form a new embryon caudex, which gradually pro- 
duces a new phimula and radicles. And as the different parts 
of the new caudex of a compound tree refemble the parts of 
the parent caudex, to which it adheres, this important circum- 
itance is (hewn beyond all doubt, that different fibrils or mole- 
cules were detached from different parts of the parent caudex 
to form the filial one. 
So in the fexual propagation of vegetables the fuperfluous liv- 
ing fibrils or molecules detached from various parts of the fyf- 
tem, and floating in the blood, appear to be fecreted from it by 
two kinds of glands only, thofe which conftitute the anthers, 
and thofe which conftitute the pericarp of flowers. By the for- 
mer I fuppofe the fibrils with formative appetencies and with 
nutritive appetencies to be fecreted ; and by the latter the mole- 
cules with formative and with nutritive propenfities. After- 
wards, that thefc fibrils with formative and nutritive appeten- 
cies become mixed in the pericarp of the flower with the cor- 
refpondent molecules with formative and nutritive propenfities, 
and Sect. XXXIX. 8. 11. 
GENERATION. 
425 
and that a newembryon is inftantly produced by their recipro- 
cal embrace and coalefcence. 
'And that parts of this new organization afterwards acquire 
new appetencies, and form new molecules, and thus gradually 
produce other parts of the growing feed, which do not at firit 
appear, as the plumula, radicles, cuticle, and the glands of re- 
production in the pericarp and anthers, which correfpond in 
the animal fetus to the lungs, inteftines, cuticle, and the organs, 
which diftinguilh the fexes, and are their parts of fecondary 
formation. 
If fecondary parts of a vegetable embryon were not fabrica- 
ted from the primary parts, or firft rudiments of it, the flowers 
of the clafs dicecia of Linneus could not produce both male 
and female feeds, as the male and female organs of reproduction 
refide on different plants. For as the male plants produce buds 
fimilar to themfelves, which may be termed male buds ; and 
the female plants produce buds fimilar to themfelves, which 
may be termed female buds, it would feem impoflible for the 
flowers to generate female feeds according to the theory of re- 
production above delivered. As the male, not being an her- 
maphrodite, cannot be fuppoled to fecrete any fibrils with ap- 
petencies proper to produce female organs, as no fuch can ex- 
ift in his blood, which muft therefore be fabricated afterwards 
by the new appetencies acquired by the new organizations of 
the growing embryon. 
ii. From this new doClrine of a three-fold vegetable mule 
by lateral propagation, as the new bud of a tree, which has had 
two feions ingrafted on it one above another ; in which it is iri- 
conteftibly fhewn, that different fibrils or molecules are detach- 
ed from different parts of the parent caudex to form the filial 
one, which adheres to it; we may fafely conclude, as it is de- 
ducible from the ftrongeft analogy, that in the production of 
fexual mules, fome parts of the new embryon were produced 
by, or detached from, fimilar parts of the parent, which they 
refemble. And that as thefe fibrils or molecules floated in the 
circulating blood of the parents, they were collected feparate- 
ly by appropriated glands of the male or female ; and that fi- 
nally on their mixture in the matrix the newembryon was gen- 
erated, refembling in fome parts the form of the father, and in 
other parts the form of the mother, according to the quantity 
or ad.ivity of the fibrils or molecules at the time of their con- 
junClion. 
And laftly, that various parts of the new organizations after- 
wards acquired new appetencies, and formed molecules with 
new propenfities, and thus gradually produced other .econdary 
Vol. I. G g g parts 426 
GENERATION. 
Sect. XXXIX. 9.1. 
parts of the growing fetus, as the (kin, nails, hair, and the or- 
gans which diftinguiffi the fexes. 
If the molecules fecreted by the female organ into the peri- 
carp of flowers, or into the ovary of animals, were fuppofed to 
confift of only unorganized or inanimate particles ; and the fi- 
brils fecreted by the male organ only to poffefs formative appe- 
tencies to feledl and combine with them ; the new embryon 
mult probably have always refembled the father, and no mules 
could have had exiftence. 
But by the theory above delivered it appears, that the new 
offspring, both in vegetable and animal reproduction, whether 
it be a mule or not, mult fometimes more refemble the male 
parent, and fometimes the female one, and fometimes to be a 
combination of them both, as in the Epigram of Aufonius. 
Bum dubitat Natura marem, faceretne puellam 
Fa&ua es, O pulcher, pene puella, Puer ! 
IX. 1. The foregoing remarks on vegetable generation are 
chiefly tranferibed from my work on Phytologia, SeCt. VII. and 
may be applied to animal reproduction ; fince from this analo- 
gy to the lateral propagation of vegetable buds, if we fuppofe, 
that redundant fibrils with formative appetencies are produced 
by, or detached from, various parts of the male animal, and cir- 
culating in his blood, are fecreted by adapted glands, and con- 
ititute the feminal fluid ; and that redundant molecules with 
formative aptitudes or propenfities are produced by, or detached 
from, various parts of the female, and circulating in her blood, 
are fecreted by adapted glands, and form a refervoir in the ova- 
ry ; and finally that when thefe formative fibrils, and forma- 
tive molecules, become mixed together in the uterus, that they 
coalcfce or embrace each other, and form different parts of the 
new embryon, as in the cicatricula of the impregnated egg ; we 
may more readily comprehend fome circumftances, which are 
difficult to underftand on any other fyftem of generation. 
It muft be obferved that this theory differs from that of M. 
Buffon ; as he conceives the fame organized particles to exift 
in the generative fecretions both of the male and female par- 
ent ; whereas in this theory it is fuppofed, that particles com- 
pletely organized are too large to pafs the glands of either fex, 
and that thofe, which are feen in the femen by microfcopes, are 
the confequence'of the ftagnation of the fluid, as in the puftules 
of the itch, and in the liquid feces of dyfenteric patients. Hence 
the fibrils with formative appetencies and the molecules with 
formative aptitudes or propenfities muft coalefce to produce the 
firft organization. 
Secondly, Sect. XXXIX. 9. 1. 
GENERATION. 
427 
Secondly, in M. Buffon's theory the fetus is fuppofed to be 
inftantaneoufly produced all at once ; whereas in our theory 
there is believed to cxift a primary, and fecondary formation ; 
that is, that many eflential parts, as the brain and the heart, are 
primarily produced from the congrefs of the fibrils with formative 
appetencies, and the molecules with formative aptitudes or pro- 
penfities ; and that thefe combinations acquire new appeten- 
cies, and produce or unite with molecules with new aptitudes, 
and thus generate other parts of fecondary formation, as ribs, 
fingers, inteftines, with the external form, and the glands, which 
conftitute the difference of the fexes. 
One great objection to the theory delivered in the former 
part of this feCtion on generation is removed by this idea of the 
exiffence of formative fibrils, and formative molecules, which 
by their coalefcence generate various parts of the embryon at 
the fame time ; which is, that in fome monffrous or imperfect 
fetufes different parts only are produced, inftead of the whole ; 
and fuch parts as would not appear to be primary ones. Such 
are the teeth and hair, which have been found in moles or falfe 
conceptions, as they exift naturally at a diftance from the brain 
and heart, which are efteemed to be the centre of vitality, and 
are firft vifible in the embryon chick. Many other parts in 
monftrous births are faid to have been completely formed, where 
no brain or heart has exifted ; the production of which on oth- 
er ideas of generation cannot be explained ; unlefs it be fup- 
pofed, that an intire embryon had been at firft generated, all of 
which had perithed, and had been abforbed, except the parts 
which conftitute the monftrous or imperfect fetus at its birth, 
which would be difficult to explain. 
Many inftances of very imperfeift fetufes are recorded by 
Monf. J. J. Sue in his Rechearches fur la Vitalite ; and in the 
Comment, of Leipfic. I. 17. p. 528. M. Sue difleCied a fetus 
of five months old, which had no head, nor cheft, nor llomach, 
nor large inteftines, and yet the inferior half of the lower belly 
was complete, with the umbilical cord, male organs of genera- 
tion, and one completgfctcrior limb, of w'hich a print is given 
in Magazin. Encyclopco. 1797. This monftrous fetus, which 
was only half of it formed, thews, that the embryon is not al- 
ways produced from one beginning, but probably from many : 
as there was no brain or heart, the connection of nerves in the 
lower part of the fpine muft have ferved the purpofe of the 
former; and a junction of the large arteries and veins muft 
have ferved the purpofe of a heart, producing a circulation like 
that in the liver, or in the aorta and vena cava of fiih. For a 
previous production and reabforption of the other more eflen- 
tial 428 
GENERATION. 
Sect. XXXIX. 9.2, 
tial parts of the fetus, as the brain and heart, with all the upper 
yarts of the body, and inteftines, would feem to be attended with 
Rill greater difficulties. 
The miflake of conceiving the embryon to begin its forma- 
tion in one point only might more readily be fallen into from 
our habitually confidering an animal as an individual entity ; 
which it feems not to be, till an union of the nerves from every 
part is formed in the common fenforium, and produces a gener- 
al fenfibility, which is thus diftinguiffied from irritability, 
which may refide in parts even when detached from the fyftem, 
as is feen in the contractions of the heart of a viper taken out 
of the body, or of limbs recently cut off. 
2. Another thing difficult to conceive from thofe theories, 
which fuppofed the firft rudiment to confift of a Tingle entity, 
was to anfwer the curious queftion, whether the brain, or heart 
and arteries were firft formed; as the motions of the arterial 
fyftem previoufly exerted feem to have been neceflary for the 
iecretion of fenforial power in the brain, and converfely thofe 
motions of the arterial fyftem feem previoufly to require 
the fenforial power derived from the brain. 
This difficulty vanifhes, when we believe, that many parts of 
the young embryon can be begun at the fame time, as various 
formative fibrils and formative molecules coalefce, as they come 
jnto contaCl w ith each other ; and thus the rudiments of the brain 
and of the heart may be fabricated at the fame inftant of time. 
3. If fibrils with formative appetencies, and molecules with 
formative aptitudes or propenfities exift in the circulation both 
of males and females, why do they not coalefce there ? This 
feems an unanfwerable objection to M. Buffon's theory, who 
holds, that organic particles exift in the circulation ; but in the 
fyftem above delivered, no organic particles exift in the blood in 
their combined ftate ; and hence no microfcopic animalcula are 
feen in blood recently drawn, though they may appear after fome 
hours flagnation ; but the formative fibrils only and formative 
molecules are believed to exift in the circulation ; and that they 
do not produce combinations there, as cannot reft 5 and as 
fuch combinations wmuld be too large to pafs the capillary vef- 
fels of the aorta, and of the pulmonary artery, and of all the 
glands, and muft there be perpetually diffevered, if they could 
be previoufly formed in the larger veffels. 
4. If fimilar organized particles were fecreted by the fexual 
glands of the male and alfo of the female, why do they not pro- 
duce parts, or rudiments, of an embryon in the male or female 
refervoirs without a reciprocal commixture. This is another 
unanfwerable objection to M. Buffon's theory, but not to that 
above Sect. XXXIX. 9. 5. 
GENERATION. 
429 
above delivered ; which latter fuppofes, that no organized par- 
ticles are fecreted either by the glands of the male or female ; 
but that the fibrils with formative appetencies are fecreted by 
the glands of the male, and the molecules with formative apti- 
tudes or propenfities are fecreted by thole of the female ; and 
that, when thefe combine, the organization commences. 
5. If the whole of the embryon is fuppofed to be fynchron- 
oufly produced, which is faid almoll to be vifible in the cicatric- 
ula of the egg even before incubation, how can this happen 
from a commixture of any kind of particles deduced from both 
the male and female parents, if thofe particles are previoufly de- 
tached from the various parts of their refpeCtive bodies ; fince 
no parts fimilar to the female organs can previoufly exift in the 
male, nor any of thofe of the male organs previoufly exift in the 
female ? This fynchronous production of all the parts of the em- 
bryon is fuppofed by M. Buffon, and militates againft his the- 
ory ; and if it was true, would equally militate againft that 
above delivered ; but from all the hiftories of the beginning and 
growing fetus given by anatomifts there are parts of fecondary 
formation, as well as parts of primary formation ; thus the head 
and fpine of the back are firft feen both in the oviparous and vi- 
viparous embryon, and afterwards the lungs, ribs, limbs, nails, 
hairs, and feathers, and laft of all perhaps the glands which dif- 
tinguilh the fexes ; as thefe are the laft, which afterwards ar- 
rive at their maturity. 
This fecondary formation of parts is evinced in the long cau- 
dexes of the buds of trees, which form a filament of the bark ; 
as from any part of this a new plumula or leaf, which is the 
lungs of the embryon bud, can be produced, when the upper 
part of a branch is lopped off, as (hewn in No. 9. 4. of this 
feCtion ; and is further evinced in fome animals, as when a 
common earth-worm is cut in halves, the tail-part can produce 
a head-part, and the head-part can produce a tail-part; and 
laftly, it is evinced from the power, which crabs poflefs of gen- 
erating a new leg, when one of them is accidentally broken off. 
This power is likewife poffeffed by the human body, as in the 
production of new teeth, and then of a fecond fet, and there are 
fome inftances on record, that a third fet of teeth have been fab- 
ricated in the jaw-bones of age. 
The power of formation of fecondary parts in the human fyf- 
tem is wonderfully (hewn by the following cafe, which is related 
by Mr. White in the Manchefter Memoirs, Vol. I. p. 338. 
" Some years ago I delivered a lady of rank of a fine boy, who 
had two thumbs on one hand, or rather one thumb double from 
the firft joint, the outer one being rather lefs than the inner, 
and 430 
GENERATION. 
Sect. XXXIX. io. i. 
and each of them having a perfeCl nail. When he was about 
three years old, I was defired to take off the leffer one; which I 
did, but to my great aftoniftiment it grew again, and along with 
it the nail. The family afterwards went to refide in London, 
when the father (hewed it to Mr. Bromfield ; who faid, that he 
fuppofed Mr. White, from fear of damaging the joint had not 
taken it wholly out, but that he would difleCk it out entirely, 
and that then it would not returq. He accordingly executed 
his plan, and turned the ball out of the focket. Notwithftand- 
ing this it grew again, a frefli nail was formed, and the thumb 
remains in this ftate." 
Recapitulation. 
X. On confidering the production of vegetable buds and 
feeds, of fome infects, and of more perfect animals, the modes 
of generation may be divided into folitary and fexual. 
i. The firft confifts either in folitary lateral generation, as 
in the reproduction of the buds or bulbs of vegetables, and of the 
young of the polypus, and of the hydra ftentorea,-or of the foli- 
tary internal generation, as of the aphis, vine-fretter, aCtinia, 
fea-anemone, tenia, tape-worm, and the volvox ; all which are 
properly a viviparous progeny, as they are not preceded by feeds, 
or fpawn, or eggs. 
In thefe modes of reproduction I fuppofe, that fibrils with 
formative appetencies, and molecules with formative aptitudes 
or propenfities, produced by, or detached from, various effential 
parts of their refpeCtive fyftems, float in the vegetable or infeCt 
blood. Thefe may be termed animalized particles of primary 
combination, confifting of a folid particle adjoined to a peculiar 
appetency or propenfity; which latter may be efteemed its ethe- 
real part, as magnetifm or electricity maybe added to iron or to 
other inanimate bodies. 
Thefe fibrils with formative appetencies, and molecules with 
formative aptitudes or propenfities, cannot unite, or continue 
united, in the circulating blood, as they are not at reft ; and 
would be too large to pafs the capillaries of the aorta, pulmo- 
nary artery, and glands, if they could be united in the larger 
veflels ; they are therefore feleCted or fecreted feparately by 
adapted glands, and when mixed together combine, and form 
the primary parts of the new organization of an embryon. 
Thofe fecreted from the long caudex of vegetable buds are 
depofited beneath the cuticle of the bark of trees, and there 
uniting form a new caudex gemmae along the fide of the parent 
one ; which has the property of producing fecondary organiza- 
tions Sect. XXXIX. 10. 2. 
GENERATION. 
431 
tions from the new powers it has acquired, fo as to form a leaf 
or lungs either at its fummit in the axilla of the parent leaf, or in 
any other part of its length ; and alfo to form radicles below, 
or from any amputated part. 
This new caudex gemmae is proved to commence its forma- 
tion in feveral places at the ^me time from the triple caudex of 
the bud of a tree, which has been twice fucceffively ingrafted, 
which we have called a triple mule ; but as the new vegetable 
confifts in general of a combination of parts derived from one 
parent, it much more accurately refembles that parent in its 
form, growth, and difeafes, than the progeny from fexual or 
feminal generation. The fame circumftances occur to the vege- 
tables, which poffefs fhort and flat caudexes, which exift be- 
tween the radicles and the root-leaves, as in the bulbs of tulips 
and onions; which might poflibly be ingrafted on each other like 
the buds of different trees, and form curious mule bulbs. 
This lateral or folitary mode of propagation belongs likewife 
to the polypus of our ditches, and to the hydra ftentorea, and 
probably to many other infers. / 
2. There is alfo a folitary internal mode of generation, which 
occurs in the viviparous productions of the aphis, which are 
known to proceed for eight or nine fucceflive generations with- 
out the congrefs of fexes ; but what is extraordinary, a con- 
grefs of fexes appears to be neceffary in their production of an 
oviparous progeny in the autumn for the prefervation of the fpe- 
cies during winter ; whence it would feem, that folitary genera- 
tion always produces a viviparous offspring. For the more par- 
ticular hiftory of this wonderful and important infeCt fee Phyt- 
ologia, SeCt. IX. and XIV. To which may be added, that a 
fimilar internal folitary mode of reproduction probably obtains 
in the tenia, or tape-worm, of the inteftines, which afflicts va- 
riety of animals, and of the aCtinea, or fea-anemone, and of the 
volvox, as defcribed in the Syftema Naturae of Linneus. 
The eflential difference between the folitary lateral generation 
and the folitary internal generation feems to confiit in this; 
that in the former there are many glands, which fecrete or pro- 
duce the fibrils with formative appetencies; and many other 
glands, which fecrete or produce the molecules with formative 
aptitudes or propehfities ; and that thefe numerous fecretions are 
mixed together and combine in one large receptacle beneath the 
cuticle of trees, and of fomc infeCls, and there combining gener- 
ate the organized particles, which conllitute the rudiment of 
the new embryon, producing many of the eflential parts of it at 
the fame time ; whereas in the latter, there probably exifts but 
®ne fet of glands, which fecrete the fibrils with formative appe- 
tencies ; 432 
GENERATION. 
Sect. XXX1X. 10. 3. 
tencies ; and another fet of glands which fecrete the molecules 
with formative propenfities ; and that thefe primary particles 
are received and mingled together in a lefs extenfive refervoir ; 
as an univerfal exiftence of procreative glands, as in the long 
caudexes of vegetable buds, might have been inconvenient to 
locomotive animals. Thefe therefore feem to conftitute a link 
of the chain of nature between the lateral production of buds, 
and the fexual hermaphrodites, which are next to be confidered. 
3. The fexual mode of propagation may be divided firft into 
hermaphrodite or reciprocal fexual generation, as in the flowers 
of moft vegetables, and in fome large infects, as in dew-worms 
and fhell-fnails, and probably in many fmaller ones. Secondly 
into the Ampler fexual generation, which occurs in the larger 
animals. 
The fexual modes of generation may alfo be divided into the 
feminal or oviparous modes, as the feeds of plants, the fpawn 
of fifh, and of infers, and the eggs of birds ; and fecondly into 
the viviparous modes, as the fummit-bulbs of fome vegetables, 
as of polygonum viviparum, magical onions, and the cloves of 
garlic ; as thefe fummit-bulbs fucceed the fexual congrcfs of the 
male and female organs of flowers ; and are not buds, as their 
roots or caudexes do not pafs down the Hem of the plant into 
the ground ; and are therefore a fexual viviparous progeny of 
vegetables : but the principal viviparous fexual productions are 
thofe of quadrupeds and of mankind. 
Next to the internal folitary mode of propagation nature feems 
to have produced the hermaphrodite fyftem of reproduction, as 
in molt flowers, and in fnails and dew-worms ; in thefe the 
mafculine and feminine organs are generally external and totally 
feparated from each other, and conflft of glands, which fecrete 
the fibrils with formative appetencies, and the molecules with 
formative propenfities from the fame mafs of blood. 
Hence in vegetable productions the trees from feed, as apple 
trees, fometimes exaCtly refemble the parent tree, like the buds 
and bulbs, which are produced without fexual intercourfe ; at 
other times they do not exaCtly refemble the parent tree, which 
feems to be owing to the anther-duft fometimes of the fame 
flower, or fometimes of other flowers in its vicinity, caufing the 
impregnation of the ftigma. But in hermaphrodite infeCts, as 
the fhell-fnail, and dew-worm, I have frequently obferved, that 
they impregnate each other reciprocally, though it is attended 
with much danger and inconvenience to them ; and I thence 
conclude, that they have net the power to impregnate them- 
fclves by the conjunction of their own organs of reproduction, 
Cnee if that had happened, the progeny would probably, like the 
, buds Sect. XXXIX. 10.4. 
GENERATION. 
433 
buds of trees, more exaCUy have refembled the parent; and no 
improvement of the fpccies, or no new fpecies from the fame 
genus, could have been procreated ; which latter circumftance 
has probably much increafed the number both of animal and 
vegetable productions. 
4. Laftly, the fimple mode of fexual generation differs from 
the reciprocal or hermaphrodite mode of generation ; as the 
glands, which conflitute the mafculine and feminine organs, fe- 
crete the fibrils with formative appetencies and the molecules 
with formative propenfities from different maffes of blood ; as a 
double fyftem of organs might have been cumberfome, if they 
had exifted together in larger and more active animals: though 
it is not improbable, that all animals were originally hermaphro- 
dite, according to the opinion of Plato in refpedt to human kind, 
as would appear from the teats or nipples, as well as the peCio- 
ral glands, which are ftill to be feen in men and in all male 
quadrupeds. 
In this mode of propagation the fibrils with formative appe- 
tencies detached from feme or many effential parts of the male 
parent, or which were formed from the blood accordant to thofe 
effential parts, are fecreted by the male organ into an adapted 
refervoir ; and the molecules with formative propenfities detachr 
ed from fome or many effential parts of the female parent, 
or which are formed from the blood accordant to thofe effen- 
tial parts, are fecreted by the female organ into an adapted ref- 
ervoir : and in this circumftance fecretion differs from nutri- 
tion ; in the latter certain particles of the blood, which were 
not previoufly ufed in the fyftem, are embraced and become a 
folid part of the animal; in the former certain particles, which 
had previoufly been ufed in the fyftem, and detached from it, 
are imbibed by adapted glands, and depofited in refervoirs, or 
detruded. See SeCt. XXXVII. 3. 
Finally when thefe are mixed together in the aft of copula- 
tion, they embrace and coalefce, and form the effential parts of 
the new embryon ; the production of which commences in 
more places than one ; as the brain and heart, with fome 
nerves, arteries, veins, and abforbent veffels, are probably form- 
ed at the fame time, and almoft inftantaneoufly. 
Thefe new fibrous combinations acquire new appetencies, 
and produce molecules by their vital activity with new aptitudes 
or propenfities , and thus gradually fabricate other fecondary 
parts either fynchronous or fucceflive ones, as the ribs, lungs, 
limbs, and finally the organs, which diftinguilh the fexes, with 
the general difference of the male and female form throughout 
the whole fyftem, according to the prevailing or preponderant 
Vol. I. Huh a&ivity 434 
GENERATION. 
Sect. XXXIX. 10. 5. 
activity or quantity of the fibrils with appetencies derived from 
the male, or the molecules with propenfities derived from the 
female. This idea differs from the theory of M. Buffon, which 
fuppofes the whole embryon to be formed at the fame time, or 
that the fexual organs are firft produced, as a centre of animali- 
zation ; but the fecondary production of thefe organs is agreea- 
ble to all obfervations on the growing chick or fetus, and is 
ftrongly countenanced by the flow progrefs of thefe parts after 
birth, which are not complete till the maturity of the animal, 
which is termed its puberty. 
The power, which the primary or effential parts of the em- 
bryon poffefs, of producing fecondary or lefs effential parts, is 
analogous to the production of a new plumula or new radicles 
by the vegetable embryon, or caudex gemmae mentioned in No. 
8. 4. of this feCtion ; and to the power with which crabs are 
furnifhed to produce a new limb, when one is broken off; and 
to that of earth-worms, which when cut in halves, can acquire 
a new head or a new tail; and to the power in a human infant 
of regenerating a fupernumerary thumb, to the production of 
a new fet of teeth, and the developement of the fexual glands 
at puberty. See No. 9. 5. of this feCtion. 
5. Some of thefe fexual reproductions confift of feeds, or 
eggs, in which the effential parts of the vegetable or of the chick 
are already formed, as may be feen in the corculum of many 
feeds, and in the cicatricula of an egg, as foon as it leaves the 
body of the hen before incubation. In this ftate the embryon 
does not continue to grow, if expofed only to the ufual degree 
of the warmth and moifture of the atmofphere, but may be long 
kept in its ftate of infenfible life ; though it will foon ferment 
or putrefy, if it be deprived of life. 
Otherwife thefe fexual productions confift of fpawn, which 
differs from eggs by the embryon not being included in 2 hard 
unyielding {hell j fo that the receptacle diftends, as the fetus 
increafes in fize ; which is feen in the fpawn of fifh and frogs, 
and in the eggs of fpiders, fnails, and many other infeCts. From 
this diftenfibility of the bag, which contains the embryons of 
fifh and infeCts, it feems more to refemble the uterus of quad- 
rupeds than the eggs of birds; as in the former the receptacle 
increafes in fize along with the fetus, and fupplies the liquor of 
the amnios, as it is wanted ; but differs by its not continuing in 
the matrix of the mother, till the exclufion of the young animal 
into the cold and dry atmofphere. 
XI. 1. Finally* we conclude, that as the inanimate particles 
or atoms of matter unite into cryftals of various forms by the 
various powers of attraction, which tome kinds of them poffefs; 
and Sect. XXXIX. n. i. 
GENERATION. 
435 
and the various aptitudes to be attra&ed, which other kinds 
poflefs ; which may be termed the ethereal properties of inani- 
mate matter ; fo the animated fibrils or molecules, which pof- 
fefs appetencies to embrace, and propenfities -to be embraced, 
which may be called their ethereal properties, coalefce, when 
they approach each other, and form organized bodies. 
When this organization begins only in a Angle point, and 
only enlarges, as it acquires new kinds of appetencies, as ex- 
plained in the former part of this feftion on Generation, I fup- 
pofe an animated being commences ; fuch as the animalcula, 
which are feen by the folar microfcope in variety of fluids, 
which have for a time ftagnated ; as in infufions of the feeds of 
plants, in the femen of animals, and of all other vegetable and 
animal recrements diffufed in water. Thefe microfcopic ani- 
mals I fuppofe are produced by the ftagnation of the femen in 
the veficulx feminales, and by the matter of the itch by ftagna- 
tion in its puftules, and by the feces by their ftagnation in the 
inteftines ; but I believe, that they do not exift in the blood, nor 
in fluids recently fecreted. Thefe microfcopic animals confti- 
tute the primordium vitse, or firft order of animal life, and prob- 
ably are not originally propagated, but Amply arife from the dif- 
folution of all vegetable or animal matter. 
This fpontaneous production of microfcopic animals appears 
from their being difcovered in a few days in all folutions of de- 
compofing vegetable and animal matters, as well after having 
been fubjeCted to the heat of boiling water as before. Thus 
Mr. Reaumur put fome boiling veal broth, and Mr. Baker put 
fome boiling hot mafhed potatoes into hot phials, which were 
clofed with glafs-ftopples ; and both of them in three days be- 
came as full of animalcula, as the fame materials put into other 
phials without being previoufly boiled. Baker on the Microfcope. 
It is probable that there exift microfcopic vegetable produc- 
tions, as well as microfcopic animals, which may not have been 
attended to owing to the quick evaporation of a drop of water 
in a microfcope ; and that thefe are firft formed fpontaneoufly 
from the decompofing recrements of vegetable or animal bodies ; 
and that they afterwards generate others rather more perfect 
than themfelves by lateral reproduction. From this kind of 
ipontaneous microfcopic vegetation, I fuppofe the green matter 
obferved by Dr. Prieftley, which gives up fo much vital air in 
the funlhine, originates ; and that it afterwards generates a fuc- 
ceeding progeny. As it is at firft flowly produced in water in 
any fituation, and afterwards is propagated with great rapidity ; 
and according to the obfervations of Senebicr it is moft quickly 
produced in water in which vegetable or animal fubftances are 
in 436 
GENERATION. 
Sect. XXXIX. u.a. 
in a ftate of diffolution. Whence fome philofophers have late- 
ly fuppofed this green matter to he of animal origin, as it chang- 
es from a globular form to that of a thread ; which has occa- 
fioned much inveftigation by Fontana, Ingenhouz, and Sene- 
bier. Journal de Phyfique par Delametherie, T. 5. 
In the fame manner the mucor, or mould, which grows on 
all decompof;ng vegetable and animal fubftances, which are at 
reft in a proper degree of moifture and warmth, and which 
thence appears to have no parent, is probably firft produced by 
the fpontaneous appetencies and aptitudes or propenfities of the 
decompofed particles of organic bodies ; and probably thefe 
new combinations are at firft microfcopic objects, which pro- 
duce others by lateral or folitary generation, more and more 
perfect and of greater magnitude than themfelvffs, but which 
never acquire the organization ncceffary for fexual reproduc- 
tion. The fungi which grow only on decaying parts of trees 
or other vegetables, as well as the mufhrooms from horfe dung, 
which commence with fmall hair-like roots, and probably never 
produce feeds, feem to arife in a fimilar manner from fpontane- 
ous microfcopic organization, improved and magnified by fuc- 
ceffive folitary generations. 
2. The fecond kind of animal production, which is properly 
generation, commences in more points than one; as in the pro- 
duction of the long caudexes of the buds of trees ; and the ani- 
mated fibrils and molecules firft combine, and form organized 
bodies; and thefe unite again, where they are in contact; and 
thus the new embryon commences in many points at once ; 
and the folitary mode of generation is fecondary to the produc- 
tion of the fmalleft microfcopic animals, which I fuppofe com- 
mence their exiftence in one point only, that is, by the produc- 
tion firft of a fingle living filament, which I formerly believed 
to be the general mode of propagation. This folitary mode of 
generation occurs in the production of the buds of all vegeta- 
bles ; and perhaps the moft imperfeCt vegetables, as truffles, and 
other fungi, are only propagated by buds to this day, not hav- 
ing yet acquired fexual organs, as feems alfo to occur in fome 
imperfeCt animals, as the polypi, hydra, and tenia. 
3. Other vegetables have acquired an hermaphrodite ftate, 
and poffefs external fexual organs, as in moft flowers ; but both 
the male and female organs acquire or produce their adapted 
fluids from the fame mats of blood, and thusrefemble hermaph- 
rodite infeCts, as fnails and worms. 
4. Other vegetables have acquired a leparation of the fexes, 
either on the fame plant, as in the clafs of vegetables termed by 
Linneus, monoecia, or on different plants, as in the clafs dioe- 
cia ; Sect. XXXIX. 1 x. 5. 
GENERATION. 
437 
cia ; the buds of which may properly be called male or female 
vegetables, and differ in ionic degree in their form and colour, 
like male and female animals ; and in this they rtfemble the 
larger animals, as their fexual glands acquire or produce their 
prolific fluids from different maffes of blood ; which is probably 
lefs cumberfome to the individual, than where both the fexual 
glands exilt in one organized fyftem. 
In all thefe vegetable and animal modes of reproduction, I 
fuppofe the new embryon to begin in many points, and in com- 
plicated animals in many more points probably than in the more 
fnnple ones; and finally, that as thefe new organized parts, or 
rudiments of the embryon, acquire new appetencies, and pro- 
duce or find molecules with new propenfities, many fecondary 
parts are afterwards fabricated. 
Thus it would appear, that all nature exifts in a ftate of per- 
petual improvement by laws imprefled on the atoms of matter 
by the great cause of causes; and that the world may (till be 
in its infancy, and continue to improve for ever and ever. 
5. Concerning the fpontaneous production of microfcopic 
animalcules, I beg leave to repeat, firft, that I fuppofe the 
imalleft ones to be formed by the coalefcence or embrace of the 
animal fibrils, which poffefs appetencies, with the animal mole- 
cules, which poffefs correfpondent propenfities ; and that the 
animal fibrils and molecules are found in all vegetable and ani- 
mal matter, as its organization becomes decompofed ; if there 
exilts along with it fullicient moifture and proper warmth. 
Secondly, that this kind of fpontaneous reproduction refem- 
bles aCtual generation in its confifting of the coalefcence of an- 
imal fibrils with appetencies and animal molecules with corref- 
pondent propenfities, that in the former they meet each other 
in the folution of animal matter, as it decompofes by ftagna- 
tian ; whereas in the latter thefe formative fibrils and molecules 
are fecreted by different glands from the blood of the parent. 
Thirdly, that the firfl: animalcules produce other ones by ac- 
tual generation, but without fexes, like the buds of trees, and 
that as many generations may occur in a day, perhaps in an 
hour, I conceive, that they may gradually acquire new organi- 
zations, and improve by addition of new parts, as of fins, mouth, 
inteffines, and finally, perhaps, fexual organs of reproduction. 
Thus the feed of a tulip produces a fmall root the fize of a pea 
the firfl: fummer, with a fummit like a blade of grafs; this dies 
in autumn, having previoufly produced a fucceflbr larger than 
itfelf, and with a ftronger leaf or fummit ; in the autumn this 
Jikewife perifhes, and a third generation is produced, which is 
itiil larger and more perfect ; till the fifth generation from the 
feed 438 
GENERATION. 
Sect. XXXIX. 12.1. 
feed becomes fo much more perfeft as to produce fexual or- 
gans of reproduction, as the flower with its anthers and ftigma. 
This curious analogy is not only fupported by the feedling 
buds of trees, which fucceed each other for ten or twelve gen- 
erations, the parent buds dying in the autumn, before they be- 
come fufficiently perfect to form the fexual organs of reproduc- 
tion in their flowers, as occurs in apple-trees ; but is alfo ob- 
fervable in a complete infect, as in the aphis, which continues 
t© propagate for nine generations from the egg without fex ; 
and then becomes fo perfect as to form fexual organs, and to 
produce an oviparous progeny. Other infects, as the moths 
and butterflies, undergo a great change of form, before they 
acquire the property of fexual reproduction ; and probably in- 
numerable other kinds of infeCts are fubject to the fame law. 
This idea of the production and changes of form of microf- 
copic animalcules is countenanced by the fmaller kinds, never, 
I believe, having been feen in their egg or infant itate ; and by 
fome of them being capable of being revived in a few hours by 
warmth and moifture after having been dry and motionlefs for 
months, as the infect named vorticella. And laftly, from the 
changeful forms, which fome of them aflume, as that which is 
called proteus. See Baker and Adams on the Microfcope. 
Thus as by the attractions, and aptitudes to be attracted, which 
exift in inanimate matter, various new bodies are produced from 
the decompofition of thofe, which previoufly exifted ; fo by the 
appetencies to embrace, and the propenfities to be embraced, in 
animalized matter, various new animalcules are formed from 
the decompofition of thofe, which previoufly exifted ; owing in 
both cafes to the immutable laws imprefl'ed both on inanimate 
and on organized matter by the great first cause. 
XII. 1. Cause and effect may be confidered as the progref- 
fion, or fuccefiive motions, of the parts of the great fyltem of 
Nature. The flate of things at this moment is the efl'ect of the 
ftate of things, which exifted in the preceding moment; and 
the caufe of the ftate of things, which fhall exift in the next 
moment. 
Thefe caufes and efleQs may be more eafily comprehended, 
if motion be confidered as a change of the figure of a group of 
bodies, as propofed in SeCt. XIV. 2. 2. inafmuch as our ideas 
of vifible or tangible objects are more diftind, than our ab- 
ftrafted ideas of their motions. Now the change of the con- 
figuration of the fyftem of nature at this moment muft be an 
effeCt of the preceding configuration, for a change of configur- 
ation cannot exift without a previous configuration ; and the 
proximate caufe of every effect muft immediately precede that 
effect. Sect. XXXIX. 12. 2. 
GENERATION. 
439 
For example, a moving ivory ball could not proceed 
onwards, unlefs it had previoufly begun to proceed ; or unlefs an 
impulfe had been previoufly given it; which previous motion or 
impulfe conftitutes a part of the laft fituation of things. 
As the effects produced in this moment of time become 
caufes in the next, we may confider the progreflive motions of 
objects as a chain of caufes only ; whofe firft link proceeded 
from the great Creator, and which have exifted from the begin- 
ning of the created univerfe, and are perpetually proceeding. 
2. Thefe caufes may be conveniently divided into two kinds, 
efficient and inert caufes, according with the two kinds of enti- 
ty fuppofed to exift in the natural world, which may be termed 
matter and fpirit, as propofed in Sect. I. and further treated of in 
Sedl. XIV. The efficient caufes of motion, or new configura- 
tion, confift either of the principle of general gravitation, which 
actuates the fun and planets; or of the principle of particular 
gravitation, as in electricity, magnetifm, heat; or of the princi- 
ple of chemical affinity, as in combuftion, fermentation, combi- 
nation ; or of the principle of organic life, as in the contraCiion 
of vegetable and animal fibres. The inert caufes of motion, or 
new configuration, confift of the parts of matter, which are in- 
troduced within the fpheres of activity of the principles above 
defcribed. Thus, when an apple falls on the ground, the prin- 
ciple of gravitation is the efficient caufe, and the matter of the 
apple-tree the inert caufe. If a bar of iron be approximated 
to a magnet, it may be termed the inert caufe of the motion, 
which brings thefe two bodies into contaCl ; while the magnetic 
principle may be termed the efficient caufe. In the fame man- 
ner the fibres, which conftitute the retina, may be called the in- 
ert caufe of the motions of that organ in vifion, while the fen- 
forial power may be termed the efficient caufe. 
3. Another more common diftribution of the perpetual chain 
of caufes and effeCts, which conftitute the motions, or chang- 
ing configurations, of the natural world, is into active and paf- 
five. Thus, if a ball in motion impinges againft another ball at 
reft, and communicates its motion to it, the former ball is faid 
to adt, and the latter to be adted upon. In this fenfe of the 
words a magnet is faid to attradf iron ; and the prick of a fpur 
to ftimulate a horfe into exertion ; fo that in this view of the 
works of nature all things may be faid either (imply to exift, or 
to exift as caufes, or to exift as effects ; that is, to exift either 
in an adlive or paffive ftate. 
This diftribution of objedts and their motions, or changes 
of pofition, has been found fo convenient for the purpofes of 
common life, that on this foundation refts the whole conftruc- 
tion 440 
GENERATION. 
Sect. XXXIX. 12. 4. 
tion or theory of language. The names of the things them- 
feives are termed by grammarians Nouns, and their modes of 
cxiftence are termed Verbs. The nouns are divided into fub- 
ftantives, which denote the principal things fpoken of; and in- 
to adjectives, which denote fome circumftances, or lefs kinds 
of things, belonging to the former. The verbs are divided into 
three kinds, fuch as denote tire exigence of things (imply, as, to 
be ; or their exiftence in an active ftate, as, to eat; or their ex- 
iftence in a palhve Hate, as, to be eaten. Whence it appears, 
that all languages confift only of nouns and verbs, with their 
abbreviations for the greater expedition of communicating our 
thoughts; as explained in the ingenious work of Mr. Horne 
Tooke, who has unfolded by a (ingle flafh of light the whole 
theory of language, which had fo long lain buried beneath the 
learned lumber of the fchools. Diverfions of Purley. Johnfon. 
London. 
4. A third divifion of caufes has been into proximate and re- 
mote ; thefe have been much fpoken of by the writers on med- 
ical fubjeCts, but without fufficient precifion. If to proximate 
and remote caufes we add proximate and remote effeCts, we 
fhall include four links of the perpetual chain of caufation ; 
which will be more convenient for the difcuffion of many phi- 
lofophical fubjeCts. 
Thus if a particle of chyle be applied to the mouth of a lac- 
teal veflel, it may be termed the remote caufe of the motions of 
the fibres, which compofe the mouth of that laCleal veflel; the 
fenforial power is the proximate caufe ; the contraCtion of the 
fibres of the mouth of the veflel is the proximate efledt; and 
their embracing the particle of chyle is the remote efFcCt ; and 
thefe four links of caufation conftitute abforption. 
Thus when we attend to the rifing fun, firft the yellow rays 
of light flimulate the fenforial power refidingin the extremities 
of the optic nerve, this is the remote caufe. 2. The fenforial 
power is excited into a ftate of aCtivity, this is the proximate 
caufe. 3. fhe fibrous extremities of the optic nerve are con- 
tracted, this is the proximate efl'cCt. 4. A pleafurable or pain- 
ful fenfation is produced in confequence of the contraCtion of 
thefe fibres of the optic nerve, this is the remote effeCt ; and 
thefe four links of the chain of caufation conftitute the fenfi- 
tive idea, or what is commonly termed the fenfation of the ri- 
fing fun. 
5. Other caufes have been announced by medical writers un- 
der the names of caufa procatarClica, and caufa proegumina, 
and caufa fine qua non. All which are links more or lefs dif- 
tant of the chain of remote caufes. 
To Sect. XXXIX. 12. 6. 
GENERATION. 
441 
To thefe mull be added the final caufe, fo called by many au*. 
thors, which means the motive, for the accomplifhment of which 
the preceding chain of caufes was put into aflion. The idea 
of a final caufe, therefore, includes that of a rational mind, 
which employs means to effect its purpofes; thus the defire of 
preferving himfelf from the pain of cold, which he has frequent- 
ly experienced, induces the favage to conflrufl his hut; the fix- 
ing (takes into the ground for walls, branches of trees for rafters, 
and turf for a cover, are a feries of fucceffive voluntary exer- 
tions ; which are fo many means to produce a certain effect. 
This effect of preferving himfelf from cold, is termed the final 
eaufe ; the confirmation of the hut is the remote effect; the ac- 
tion of the mufcular fibres of the man, is the proximate effect; 
the volition, or activity of defire to preferve himfelf from cold, 
is the proximate caufe; and the pain of cold, which excited 
that defire, is the remote caufe. 
6. This perpetual chain of caufes and effects, the firfl link of 
which is rivetted to the throne of God, divides itfelf into innu- 
merable diverging branches, which, like the nerves arifing from 
the brain, permeate the moft minute and moft remote extremi- 
ties of the fyflem, diffufing motion and fenfation to the whole. 
As every caufe is fuperior in power to the effect, which it has 
produced, fo our idea of the power of the Almighty Creator 
becomes more elevated and fublime, as we trace the opera- 
tions of nature from caufe to caufe, climbing up the links of 
thefe chains of being, till we afcend to the Great Source of all 
things. 
Hence the modern difcoveries in chemiflry and in geology, 
by having traced the caufes of the combinations of bodies to 
remoter origins, as well as thofe in aflronomy, which digni- 
fy the prefent age, contribute to enlarge and amplify our ideas 
of the power of the Great Firfl Caufe. And had thofe ancient 
philofophers, who contended that the world was formed from 
atoms, afcribed their combinations to certain immutable prop- 
erties received from the hand of the Creator, fuch as general 
gravitation, chemical affinity, or animal appetency, inflead of 
afcribing them to a blind chance ; the doctrine of atoms, as con- 
flituting or compofing the material world by the variety of their 
combinations, fo far from leading the mind to atheifm, would. 
(Irengthen the demonitration of the exiftence of a Deity, as the 
firft caufe of all things ; becaufe the analogy refulting from our 
perpetual experience of caufe and effetl would have thus been 
exemplified through univerfal nature. 
'The heavens declare the Glory of God, and the firmament 
fbeivetb his handyivork ! One day telleth another> and one night 
Vol. I. ' I x i sei tifeth 442 
GENERATION. 
Sect. XXXIX. 12. 6. 
ceriifieth another ; they have neither fpeech nor language, yet their 
voice is gone forth into all lands, and their words into the ends of the 
•world. Manifold are thy works, O Lord ! in wifdoin hajl thou 
made them all. Pfal. xix. civ. 
SECT. Sect. XL. 
OCULAR SPECTRA. 
443 
SECT. XL. 
On the Ocular Spectra of Light and Colours, by Dr. R. W. 
Darwin, of Shrewfbury. Reprinted, by permiffion, from the 
Philofophical Tranfa&ions, Vol. LXXVI. p. 313. 
Spectra offour binds. I. Activity of the retina in vifion. 2. Spec- 
tra from defect of fenfibility. 3. Spectra from excefs of fenfibili- 
ty. 4. Of direct ocular fpedtra. 5. Greater fimulus excites 
the retina into fpafmodic adtion. 6. Of reverfe ocular fpectra. 
Greater fimulus excites the retina into various fucceffive fpaf- 
modic actions. 8. Into fixed fpafmodic action. 9. Into tempora- 
ry paralyfis. 1 o. Mfcellaneous remarks ; 1. Direlt and re- 
verfe fpeltra at the fame time. A fpeclral halo. Rule to prede- 
termine the colours of fpectra. 2. Variation of fpectra from ex- 
traneous light. 3. Variation of fpePtra in number, figure > and 
remiffion. 4. Circulation of the blood in the eye is vifible. 5. A 
new way of magnifying objects. Conclufion. 
When any one has long and attentively looked at a bright 
object, as at the fetting fun, on clofing his eyes, or removing 
them, an image, which refembles in form the object he was at- 
tending to, continues fome time to be vifible ; this appearance 
in the eye we (hall call the ocular fpebtrum of that object. 
Thefe ocular fpecSlra are of four kinds : ift, Such as are 
owing to a lets fenfibility of a defined part of the retina ; or 
ipeftra from defect of fenfibility. 2d, Such as are owing to a 
greater fenfibility of a defined part of the retina ; or fpeStra from 
excefs of fenfibility. 3d, Such as refcmble their object in its 
colour as well as form ; which may be termed direct ocular fpec- 
tra. 4th, Such as are of a colour contrary to that of their object; 
which may be termed reverfe ocular fpectra. 
The laws of light have been moll fuccefsfully explained by 
the great Newton, and the perception of vifible objects has been 
ably inveftigated by the ingenious Dr. Berkeley and M. Male- 
branche ; but thefe minute phenomena of vifion have yet been 
thought reducible to no theory, though many philofophers have 
employed a confiderable degree of attention upon them : among 
thefe are Dr. Jurin, at the end of Dr. Smith's Optics ; M. 
jEpinus, in the Nov. Com. Petropol. V. 10.; M. Beguelin, in 
the Berlin Memoires, V. II. 1771 *, M. d'Arcy, in the Hiftoire 
de 1'Acad. des Scienc. 1765 ; M. de la Hire; and, laftly, the 
celebrated M. de Bufibn, in the Memoires de 1'Acad. des Scien. 
who 444 
OCULAR SPECTRA. 
Sect. XL. 1. 1. 
who has termed them accidental colours, as if fubjefted to no 
eftablifhed laws, Ac. Par. 1743. M. p. 215. 
I muft here apprize the reader, that it is very difficult for dif- 
ferent people to give the fame names to various (hades of colours; 
whence, in the following pag<§, fomething muft be allowed, if 
pn repeating the experiments the colours here mentioned (hould 
not accurately correfpond with his own names of them. 
1. Activity of the Retina in Vifon. 
From the fubfequent experiments it appears, that the retina 
is in an active not in a paffive ft ate during the exiftence of thefe 
ocular fpe&ra ; and it is thence to be concluded, that all vifion 
is owing to the activity of this organ. 
i. Place a piece of red filk, about an inch in diameter, as in 
plate i, at Sett. III. i, on a fheet of white paper, in a ftrong 
light; look fteadily upon it from about the diftance of half a 
yard for a minute ; then doling your eyelids cover them with 
your hands, and a green fpe&rum will be feen in your eyes, re- 
fembling in form the piece of red filk : after fome time, this 
fpedrum will difappear and Ihortly reappear ; and this alter- 
nately three or four times, if the experiment is well made, till at 
length it vanilhes' entirely. 
2. Place on a flieet of white paper a circular piece of blue 
filk, about four inches in diameter, in the funlbine ; cover the 
centre of this with a circular piece of yellow filk, about three 
inches in diameter ; and the centre of the yellow filk with a cir- 
cle of pink filk, about two inches in diameter ; and the centre 
of the pink filk with a circle of green filk, about one inch in 
diameter j and the centre of this with a circle of indigo, about 
half an inch in diameter ; make a fmall fpeck with ink in the 
very centre of the whole, as in plate 3, at Sed. III. 3. 6.; look 
fteadily for a minute on this central fpot, and then clofing your 
eyes, and applying your hand at about an inch diftance before 
them, fo as to prevent too much or too little light from palfing 
through the eyelids, you will fee the moft beautiful circles of 
colours that imagination can conceive, which are moft refembled 
by the colours occafioned by pouring a drop or two of oil on a 
ftill lake in a bright day ; but thefe circular irifes of colours are 
not only different from the colours of the filks above mention- 
ed, but are at the fame time perpetually changing as long as 
they exift. 
3. When any one in the dark preffes either corner of his 
eye with his finger, and turns his eye away from his finger, he 
wil] fee a circle of colours like thofe in a peacock's tail: and a 
fudden Sect. XL. 1. 4. 
OCULAR SPECTRA. 
445 
hidden flafh of light is excited in the eye by a ftroke on it. 
(Newton's Opt. Q^i6.) 
4. When any one turns round rapidly on one foot, till he 
becomes dizzy, and falls upon the ground, the fpeftra of the 
ambient objects continue to prefent themfelves in rotation, or 
appear to librate, and he feems to behold them for fome time 
ftill in motion. 
From all thefe experiments it appears, that the fpeftra in the 
eye are not owing to the mechanical impulfe of light imprefled 
on the retina, nor to its chemical combination with that organ, 
nor to the abforption and emiffion of light, as is obferved in 
many bodies ; for in all thefe cafes the fpeftra muft either re- 
main uniformly, or gradually diminifh ; and neither their alter- 
nate prefence and evanefcence as in the firft experiment, nor 
the perpetual changes^of their colours as in the fecond, nor the 
flafh of light or colours in the prefled eye as in the third, nor the 
rotation or libration of the fpeftra as in the fourth, could exift. 
It is not abfurd to conceive, that the retina may be ftimulated 
into motion, as well as the red and white mufcles which form 
our limbs and veflels ; fince it confifts of fibres, like thofe, inter- 
mixed with its medullary fubftance. To evince this ftrufture, 
the retina of an ox's eye was fufpended in a glafs of warm 
water, and forcibly torn in a few places; the edges of thefe 
parts appeared jagged and hairy, and did not contract, and be- 
come fmooth like fimple mucus, when it is diftended till it 
breaks ; which fhews that it confifts of fibres : and its fibrous 
conftruftion became ftill more diftinft to the fight, by adding 
fome cauftic alkali to the water, as the adhering mucus was firft' 
eroded, and the hair-like fibres remained floating in the veflel. 
Nor does the degree of tranfparency of the retina invalidate the 
evidence of its fibrous ftrufture, fince Leeuwenhoek has fhewn 
that the cryftalline humour itfelf confifts of fibres. (Arcana 
Naturae, Vol. I. p. 70.) 
Hence it appears, that as the mufcles have larger fibres inter- 
mixed with a fmaller quantity of nervous medulla, the organ of 
vifion has a greater quantity of nervous medulla intermixed with 
fmaller fibres ; and it is probable that the locomotive mufcles, 
as well as the vafcular ones, of microfcopic animals have much 
greater tenuity than thefe of the retina. 
And befides the fimilar laws, which will be fhewn in this 
paper to govern alike the actions of the retina and of the muf- 
cles, there are many other analogies which exift between them. 
They are both originally excited into aftion by irritations, both 
aft nearly in the fame quantity of time, are alike ftrengthened 
or fatigued by exertion, are alike painful if excited into aftion 
when 446 
OCULAR SPECTRA. 
Sect. XL. 2.1. 
when they are in an inflamed ftate, are alike liable to paralyfis, 
and to the torpor of old age. 
IL Of spectra from defect of sensibility. 
'The retina is not Jo eajdy excited into action by lefs irritation after 
having been lately fubjeEled to greater. 
i. When any one pafles from the bright day-light into a dark- 
ened room, the irifes of his eyes expand themfelves to their ut- 
moft extent in a few feconds of time ; but it is very long before 
the optic nerve, after having been {Emulated by the greater light 
of the day, becomes fenfible of the lefs degree of it in the room ; 
and, if the room is not too obfeure, the irifes will again contrafh 
themfelves in fome degree, as the fenfibility of the retina returns. 
2. Place about half an inch fquare of ^hite paper on a black 
hat, and looking fteadily on the centre of it for a minute, remove 
your eyes to a flieet of white paper; and after a fecond or two 
a dark fquare will be feen on the white paper, which will con- 
tinue fome time. A fimilar dark fquare will be feen in the 
clofed eye, if light be admitted through the eyelids. 
So after looking at any luminous objeft of a fmall fize, as at 
the fun, for a fliort time, fo as not much to fatigue the eyes, 
this part of the retina becomes lefs fenfible to fmaller quantities 
of light; hence, when the eyes are turned on other lefs lumi- 
nous parts of the Iky, a dark fpot is feen refembling the ihape of 
the fun, or other luminous object which we laft beheld. This 
is the fource of one kind of the dark-coloured mufece volitantes. 
If this dark fpot lies above the centre of the eye, we turn our eyes 
that way, expecting to bring it into the centre of the eye, that we 
may view it more diftimStly ; and in this cafe the dark fpeftrum 
feems to move upwards. If the dark fpeftrum is found beneath 
the centre of the eye, we purfue it from the fame motive, and it 
feems to move downwards. This has given rife to various 
conjectures of fomething floating in the aqueous humours of 
the eyes ; but whoever, in attending to thefe fpots, keeps his 
eyes unmoved by looking fteadily at the corner of a cloud, at 
the fame time that he obferves the dark fpeftra, will be thor- 
oughly convinced, that they have no motion but what is given 
to them by the movement of our eyes in purfuit of them. Some- 
times the form of the fpeftrum, when it has been received from 
a circular luminous body, will become oblong; and fometimes 
it will be divided into two circular fpeftra, which is not owing 
to our changing the angle made by the two optic axifes, accord- 
ing to the diftance of the clouds or other bodies to which the 
fpeftrum Sect. XL. 2.3. 
OCULAR SPECTRA. 
447 
fpeclrum is fuppofed to be contiguous, but to other caufes men- 
tioned in No. X. 3. of this feflion. The apparent fize of it 
will alfo be variable according to its fuppofed diftance. 
As thefe fpe&ra are more eafily obfervable when our eyes are 
a little weakened by fatigue, it has frequently happened, that peo- 
ple of delicate conftitutions have been much alarmed at them, 
fearing a beginning decay of their fight, and have thence fallen 
into the hands of ignorant oculifts ; but I believe they never are 
a prelude to any other difeafe of the eye, and that it is from 
habit alone, and our want of attention to them, that we do not 
fee them on all ebj edits every hour of our lives. But as the 
nerves of very weak people lofe their fenfibility, in the fame 
manner as their mufcles lofe their activity, by a fmall time of 
exertion, it frequently happens, that fick people in the extreme 
debility of fevers are perpetually employed in picking fome- 
thing from the bed-clothes, occafioned by their miftaking the 
appearance of thefe mufca •uolitantes in their eyes. Benvenuto 
Celini, an Italian artift, a man of ftrong abilities, relates, that 
having pafled the whole night on a diltant mountain with fome 
companionsand a conjurer, and performed many ceremonies to 
raife the devil, on their return in the morning to Rome, and 
looking up when the fun began to rife, they faw numerous dev- 
ils run on the tops of the houfes, as they pafled along ; fo much 
were the fpeflra of their weakened eyes magnified by fear, and 
made fubfervient to the purpofes of fraud or fuperftition. (Life 
of Ben. Celini.) 
3. Place a fquare inch of white paper on a large piece of 
ftraw-coloured filk ; look fteadily fometime on the white paper, 
and then move the centre of your eyes on the filk, and a fpec- 
trum of the form of the paper will appear on the filk, of a deep- 
er yellow than the other part of it: for the central part of the 
retina, having been fome time expofed to the ftimulus of a greater 
quantity of white light, is become lefs fenfible to a fmaller quan- 
tity of it, and therefore fees only the yellow rays in that part of 
the ftraw-coloured filk. 
Facts fimilar to thefe are obfervable in other parts of our 
fyftem : thus, if one hand be made warm, and the other expofed 
to the cold, and then both of them immerfed in fubtepid water, 
the water is perceived warm to one hand, and cold to the other; 
and we are not able to hear weak founds for fome time after we 
have been expofed to loud ones; and we feel a chillinefs on com- 
ing into an atmofphere of temperate warmth, after having been 
fome time confined in a very warm room : and hence the ftom- 
ach, and other organs of digeftion, of thofe who have been ha- 
bituated to the greater ftimulus of fpirituous liquor, are not ex- 
cited 448 
OCULAR SPECTRA. 
Sect. XL. 3.1. 
cited into their due adion by the lefs ftimulus of common food 
alone ; of which the immediate confequence is indigeftion and 
hypochondriacifm. 
III. Of spectra from excess of sensibility. 
The retina is more eafly excited into action by greater irritation after 
having been lately fubjeHed to lefs. 
i. If the eyes are clofed, and covered perfeftly with a hat, 
for a minute or two, in a bright day ; on removing the hat a 
red or crimfon light is feen through|he eyelids. In this exper- 
iment the retina, after being fome time kept in the dark, becomes 
fo fenfible to a fmall quantity of light, as to perceive diftinftly 
the greater quantity of red rays than of others which pafs through 
the eyelids. A fimilar coloured fight is feen to pafs through the 
edges of the fingers, when the open hand is oppofed to the flame 
of a candle. 
2. If you look for fome minutes fteadily on a window in the 
beginning of the evening twilight, or in a dark day, and then 
move your eyes a little, fo that thofe parts of the retina, on 
which the dark frame-work of the window was delineated, may 
now fall on the glafs part of it, many luminous lines, repre- 
fenting the frame-work, will appear to lie acrofs the glafs panes : 
for thofe parts of the retina, which were before leaft ftimulated 
by the dark frame-work, are now more fenfible to light than the 
other parts of the retina which were expofed to the more lu- 
minous parts of the window. 
3. Make with ink on white paper a very black fpot, about 
half an inch in diameter, with a tail about an inch in length, fo 
as to reprefent a tadpole, as in plate 2, at Sed. III. 8..3. ; look 
fteadily for a minute on this fpot, and, on moving the eye a lit- 
tle, the figure of the tadpole will be feen on the white part of 
the paper, which figure of the tadpole will appear whiter or 
more luminous than the other parts of the white paper ; for the 
part of the retina on w'hich the tadpole was delineated, is now 
more fenfible to light than the other parts of it, which were ex- 
pofed to the white paper. This experiment is mentioned by 
Dr. Irwin, but is not by him afcribed to the true caufe, namely, 
the greater fenfibility of that part of the retina which has been 
expofed to the black fpot, than of the other parts which had re- 
ceived the white field of paper, which is put beyond a doubt by 
the next experiment. 
4. On doling the eyes after viewing the black fpot on the 
white paper, as in the foregoing experiment, a red fpot is feen 
of Sect. XL. 3.5/ 
OCULAR SPECTRA. 
449 
of the form of the black fpot: for that part of the retina, on which 
the black fpot was delineated, being now more fcnfible to light 
than the other parts of it, which were expofed to the white pa- 
per, is capable of perceiving the red rays which penetrate the 
eyelids. If this experiment be made by the light of a tallow 
candle, the fpot will be yellow inftead of red ; for tallow can- 
dles abound much with yellow light, which paffes in greater 
quantity and force through the eyelids than blue light ; hence 
the difficulty of diftinguiffiing blue and green by this kind of 
candle light. The colour of the fpe&rum may poffibly vary in 
the daylight, according to the different colour of the meridian 
or the morning or evening light. 
M. Beguelin, in the Berlin Memoires, V. II. 1771, obferves, 
that when he held a book fo that the fun ffione upon his half- 
clofed eyelids, the black letters, which he had long infpefted, 
became red, which mult have been thus occafioned. Thofe 
parts of the retina which had received for fome time the black 
letters, were fo much more fenfible than thofe parts which had 
been oppofed to the white paper, that to the former the red 
light, which paffed through the eyelids, was perceptible. There 
is a fimilar ftory told, I think, in M. de Voltaire's Hiftorical 
Works, of a Duke of Tufcany, who was playing at dice with 
the general of a foreign army, and, believing he faw bloody 
fpots upon the dice, portended dreadful events, and retired in 
confuiion. The obferver, after looking for a minute on the 
black fpots of a die, and carelefsly clofing his eyes, on a bright 
day, would fee the image of a die with red fpots upon it, as 
above explained. 
5. On emerging from a dark cavern, where we have long 
continued, the light of a bright day becomes intolerable to the 
eye for a confiderable time, owing to the excefs of fenfibility ex- 
iting in the eye, after having been long expofed to little or no 
ftimulus. This occafions us immediately to contrail the iris to 
its fmalleft aperture, which becomes again gradually dilated, as 
the retina becomes accuftomed to the greater ftimulus of the 
daylight. 
The twinkling of a bright ftar, or of a diftant candle in the 
night, is perhaps owing to the fame caufe. While we continue 
to look upon thefe luminous objects, their central parts gradu- 
ally appear paler, owing to the decreafing fenfibility of the part 
of the retina expofed to their light; whilft, at the fame time, 
by the unfteadinefs of the eye, the edges of them are perpetually 
falling on parts of the retina that were juft before expofed to 
the darknefs of the night, and therefore tenfold more fenfible to 
light than the part on which the ftar or candle had been for 
Vol. I. K k k fom® 450 
OCULAR SPECTRA. 
SpcT. XL. 4. n 
fome time delineated. This pains the eye in a fimilar manner 
as when we come fuddenly from a dark room into bright day- 
light, and gives the appearance of bright fcintillations. Hence 
the ftars twinkle molt when the night is darkeft, and do not 
twinkle through telefcopes, as obferved by Mufchenbroeck; and 
it will afterwards be feen why this twinkling is fometimes of 
different colours when the object is very bright, as Mr. Melvill 
obferved in looking at Sirius. For the opinions of others on 
this fubjedt, fee Dr. Prieftley's valuable Hiftory of Light and 
Colours, p. 494. 
Many fa 61s obfervable in the animal fyftem are fimilar to 
thefe ; as the hot glow occafioned by the ufual warmth of the 
air, or our clothes, on coming out of a cold bath ; the pain of 
the fingers on approaching the fire after having handled fnow ; 
and the inflamed heels from walking in fnow. Hence thofe 
who have been cxpofed to much cold have died on being brought 
to a fire, or their limbs have become fo much inflamed as to 
mortify. Hence much food or wine given fuddenly to thofe 
who have almoft perifhed by hunger has deftroycd them ; for 
all the organs of the famifhed body are now become fo much 
more irritable to the ftimulus of food and wine, which they 
have long been deprived of, that inflammation is excited, which 
terminates in gangrene or fever. 
* IV. Of direct ocular spectra. 
A quantity of fnmilus fomewhat greater than natural excites the 
retina Into fpafmodic aHion, which ceafes in a few feconds. 
A certain duration and energy of the ftimulus of light 
and colours excites the perfect action of the retina in vifion ; 
for very quick motions are imperceptible to us, as well as very 
flow ones, as the whirling of a top, or the fhadow on a fun-dial. 
So perfect darknefs does not affect the eye at all ; and excels 
of light produces pain, not vifion. 
i. When a fire-coal is whirled round in the dark, a lucid cir- 
cle remains a confiderable time in the eye ; and that with fo 
much vivacity of light, that it is millaken for a continuance of 
the irritation of the object. In the fame manner, when a fiery 
meteor (hoots acrofs the night, it appears to leave a long lucid 
train behind it, part of which, and perhaps fometimes the whole, 
is owing to the continuance of the acflion of the retina after 
having been thus vividly excited. This is beautifully illuftrated 
by the following experiment : fix a paper fail, three or four 
inches in diameter, and made like that of a fmoke jack, in a tube 
of Sect. XL. 4. 2. 
OCULAR SPECTRA. 
451 
o£ pafteboard ; on looking through the tube at a diftant prof- 
ped, fome difjointcd parts of it will be feen through the nar- 
row intervals between the fails ; but as the fly begins to revolve, 
thefe intervals appear larger ; and when it revolves quicker, the 
whole profped is feen quite as diftind as if nothing intervened, 
though lefs luminous. , 
2. Look through a dark tube, about half a yard long, at the 
area of a yellow circle of half an inch diameter, lying upon a 
blue area of double that diameter, for half a minute ; and on 
doling your eyes the colours of the fpedrum will appear fimiiar 
to the two areas, as in fig. 3.; but if the eye is kept too long 
upon them, the colours of the fpedrum will be the reverfe of 
thofe upon the paper, that is, the internal circle will become 
blue, and the external area yellow ; hence fome attention is re- 
quired in making this experiment. 
3. Place the bright flame of a fpermaceti candle before a black 
object in the night ; look fteadily at it for a fhort time, till it is 
obferved to become fomewhat paler ; and on clofing the eyes, 
and covering them carefully, but not fo as to comprefs them, the 
image of the blazing candle will continue diftindly to be vifible. 
Look fteadily, for a ihort time, at a window in a dark day, as 
in Exp. 2. Sed. III. and then clofing your eyes, and covering 
them with your hands, an exact delineation of the window re- 
mains for fome time vifible in the eye. This experiment re- 
quires a little pradice to make it fucceed well ; fince, if the 
eyes are fatigued by looking too long on the window, or the day 
be too bright, the luminous parts of the window will appear 
dark in the fpedrum, and the dark parts of the frame-work will 
appear luminous, as in Exp. 2. Sed- III. And it is even diffi- 
cult for many, who firft try this experiment, to perceive the 
fpedrum at all; for any hurry of mind, or even too great atten- 
tion to the fpedrum itfelf, will difappoint them, till they have 
had a little experience in attending to fuch fmall fenfations. 
The fpedra defcribed in this fedion, termed dired ocular 
fpedra, are produced without much fatigue of the eye ; the ir- 
ritation of the luminous objed being foon withdrawn, or its 
quantity of light being not fo great as to produce any degree of 
uneafinefs in the organ of vifion ; which diftinguiffies them 
from the nextclafs of ocular fpedra, which are the confequence 
of fatigue. Thefe dired fpedra are belt obferved in fuch cir- 
cumftances that no light, but what comes from the objed, can 
fall upon the eye ; as in looking through a tube, of half a yard 
long, and an inch wide, at a yellow paper on the fide of a room, 
the dired fpedrum was eafily produced on.clofing the eye with- 
out taking it from the tube ; but if the lateral light is admitted 
through 452 
OCULAR SPECTRA. 
Sect. XL. 5.1. 
through the eyelids, or by throwing the fpedrum on white 
paper, it becomes a reverfe fpedrum, as will be explained be- 
low. 
The other fenfes alfo retain for a time the impreffions that 
have been made upon them, or the adions they have been ex- 
cited into. So if a hard body is preffed upon the palm of the 
hand, as is pradifed in tricks of legerdemain, it is not eafy to 
diftinguifh for a few feconds whether it remains or is removed ; 
and taftes continue long to exift vividly in the mouth, as the 
fmoke of tobacco, or the tafte of gentian, after the fapid mate- 
rial is withdrawn. 
V. A quantity of fimulus fomeuhat greater than the laf mentioned 
excites the retina into fpafmodic ahi ion, 'which ceafes and recurs 
alternately. 
i. On looking for a time on the fetting fun, fo as not great- 
ly to fatigue the fight, a yellow fpedrum is feen when the eyes 
are clofed and covered, which continues for a time, and then 
difappears and recurs repeatedly before it entirely vaniihes. 
This yellow fpedrum of the fun when the eyelids are opened 
becomes blue ; and if it is made to fall on the green grafs, or on 
other coloured objects, it varies its own colour by an intermix- 
ture of theirs, as will be explained in another place. 
2. Place a lighted fpermaceti candle in the night about one 
foot from your eye, and look fteadily on the centre of the flame, 
till your eye becomes much more fatigued that in Sed. IV. 
Exp. 3.; and ©n doling your eyes a reddilh fpedrum will be 
perceived, which will ceafe and return alternately. 
The adion of vomiting in like manner ceafes, and is renew- 
ed by intervals, although the emetic drug is thrown up with the 
fir ft effort ; fo after-pains continue fome time after parturition ; 
and the alternate pulfations of the heart of a viper are renew- 
ed for fome time after it is cleared from its blood. 
VI. Of reverse ocular spectra. 
he retina, after having been excited into action by a fimulus [ome- 
•what greater than the laf mentioned, falls into oppofte fpafmodic 
action. 
The adions of every part of animal bodies may be advanta- 
geoufly compared with each other. This ftrid analogy con- 
tributes much to the inveftigation of truth; while thofe loofer 
analogies, which compare the phenomena of animal life with 
tliofe Sect. XL. 6.1. 
OCULAR SPECTRA. 
453 
thofe of chemiftry or mechanics, only ferve to miilead our in- 
cjuiries. 
When any of our larger mufcles have been in long or in violent 
action, and their antagonifts have been at the fame time extend- 
ed, as toon as the action of the former ceafes, the limb is ftretch- 
ed the contrary way for our eafe, and a pandiculation or yawn- 
ing takes place. 
By the following obfervations it appears, that a fimilar cir- 
cumftance obtains in the organ of vifion ; after it has been fa- 
tigued by one kind of action, it fpontaneoufly falls into the op- 
pofite kind. 
i. place a piece of coloured Glk, about an inch in diameter, 
on a fheet of white paper, about half a yard from your eyes ; 
look fteadily upon it for a minute , then remove your eyes up- 
on another part of the white paper, and a fpe&rum will be feen 
of the form of the iilk thus infpe&ed, but of a colour oppolite 
to it. A fpeftrum nearly fimilar will appear if the eyes are 
clofed, and the eyelids fhaded by approaching the hand near 
them, fo as to permit fome, but to prevent too much light fall- 
ing on them. 
Red filk produced a green fpe&rum. 
Green produced a red one. 
Orange produced blue. 
Blue produced orange. 
Yellow produced violet. 
Violet produced yellow. 
That in thefe experiments the colours of the fpeftra are the 
reverfe of the colours which occafioned them, may be feen by 
examining the third figure in Sir Ifaac Newton's Optics, L. II. 
p. i. where thofe thin laminae of air, which reflected yellow, 
tranfmitted violet; thofe which reflected red, tranfmitted a blue 
green ; and fo of the reft, agreeing with the experiments above 
related. 
2. Thefe reverfe fpeclra are fimilar to a colour, formed by a 
combination of all the primary colours except that with which 
the eye has been fatigued in making the experiment: thus the 
reverfe fpedtrum of red muft be fuch a green as would be pro- 
duced by a combination of all the other prifmatic colours. To 
evince this fact the following fatisfaciory experiment was made. 
The prifmatic colours were laid on a circular pafteboard wheel, 
about four inches in diameter, in the proportions defcribed in 
Dr. Prieftley's hiftory of Light and Colours, pl. 12. fig. 83. ex- 
cept that the red compartment was entirely left out, and the 
others proportionably extended fo as to complete the circle. 
1 hen, as the orange is a mixture of red and yellow, and as the 
violet 454 
OCULAR SPECTRA. 
Sect. XL. 6. 3. 
violet is a mixture of red and indigo, it became neceflary to put 
yellow on the wheel inftead of orange, and indigo inftead of vi- 
olet, that the experiment might more exadly quadrate with the 
theory it was defigned to eftablifh or confute ; becaufe in gain- 
ing a green fpedrum from a red objed, the eye is fuppofed to 
have become infenfible to red light. This wheel, by means of 
an axis, was made to whirl like a top ; and on its being put in 
motion, a green colour was produced, correfponding with great 
exadnefs to the reverfe fpedrum of red. 
3. In contemplating any one of thefe reverfe fpedra in the 
clofed and covered eye, it difappears and reappears feveral times 
fucceffively, till at length it entirely vanifhes, like the dired 
fpedra in Sed. V.; but with this additional circumftance, that 
when the fpedrum becomes faint or evanefeent, it is inftantly 
revived by removing the hand from before the eyelids, fo as to 
admit more light : becaufe then not only the fatigued part of 
the retina is inclined fpontaneoufly to fall into motions of a 
contrary diredion, but being ftill fenfible to all other rays of 
light, except that with which it was lately fatigued, is by thefe 
rays at the fame time ftimulated into thofe motions which form 
the reverfe fpedrum. 
From thefe experiments there is reafon to conclude, that the 
fatigued part of the retina throws itfelf into a contrary mode of 
adion, like ofeitation or pandiculation, as foon as the ftimulus 
which has fatigued it is withdrawn ; and that it ftill remains 
fenfible, that is, liable to be excited into adion by any other col- 
ours at the fame time, except the colour with which it has been 
fatigued. 
VII. The retina, after having been excited into aTton by a ftimulus 
fomewhat greater than the I aft mentioned, falls into various fuc- 
ceffive fpapnodic actions. 
i. On looking at the meridian fun as long as the eyes can 
well bear its brightnefs, the dilk firft becomes pale, with a lu- 
minous crefcent, which feems to librate from one edge of it to 
the other, owing to the unfteadinefs of the eye ; then the whole 
phafis of the fun becomes blue, furrounded with a white halo; 
and on doting the eyes, and covering them with the hands, a 
yellow fpedrum is feen, which in a little time changes into a 
blue one. 
M. de la Hire obferved, after looking at the bright fun, that 
the impreflion in his eye firft affumed a yellow appearance, and 
then green, and then blue; and wifhes to afcribe thefe appear- 
ances to fome afiedion of the nerves. (Porterfield on the Eye, 
Vol. I. p. 343-) 2. After Sect. XL. 7. 2. 
OCULAR SPECTRA. 
455 
2. After looking fteadily on about an inch fquare of pink filk, 
placed on white paper, in a bright funfhine, at the diftance of 
a foot from my eyes, and doling and covering my eye-lids, the 
fpedrum of the filk was at firft a dark green, and the fpedrum 
of the white paper became of a pink. The fpedra then both 
difappeared ; and then the internal fpedrum was blue ; and then, 
after a fecond difappearance, became yellow, and laftly pink, 
whilft the fpeCtrum of the field varied into red and green. 
Thefe fucceflions of different coloured fpedra were not exact- 
ly the fame in the different experiments, though obferved, as 
near as could be, with the fame quantity of light and other fim- 
ilar circumftances ; owing, I fuppofe, to trying too many exper- 
iments at a time ; fo that the eye was not quite free from the 
fpedra of the colours which were previoufly attended to. 
The alternate exertions of the retina in the preceding fedion 
refembled the ofcitation or pandiculation of the mufcles, as they 
were performed in directions contrary to each other, and were 
the confequence of fatigue rather than of pain. And in this they 
differ from the fucceifive diffimilar exertions of the retina, men- 
tioned in this fection, which refemble in miniature the more 
violent agitations of the limbs in convulfive difeafes, as epilepfy, 
chorea S. Viti, and opifthotonos ; all which difeafes are perhaps, 
at firft, the confequence of pain, and have their periods after- 
wards eftablifhed by habit. 
VIII. The retina, after having been excited into action by a fiimulus 
fomewhat greater than the lafi mentioned, falls into a fixed fpaf- 
inodic action, which continues forfame days. 
i. After having looked long at the meridian fun, in making 
fome of the preceding experiments, till the dilk faded into a 
pale blue, I frequently obfervcd a bright blue fpedtrum of the 
fun on other objects all the next and the fucceeding day, which 
conftantly occurred when I attended to it, and frequently when 
I did not previoufly attend to it. When I clofed and covered 
my eyes, this appeared of a dull yellow ; and at other times mix- 
ed with the colours of other objects on which it was thrown, 
ft may be imagined, that this part of the retina was become in- 
fenfible to white light, and thence a bluifh fpetSlrum became vif- 
ible on all luminous objects ; but as a yellowifh fpedtrum was alfo 
teen in the clofed and covered eye, there can remain no doubt 
of this being the fpedlrum of the fun. A fimilar appearance 
was obierved by M. ^Epinus, which he acknowledges he could 
give no account of. (Nov. Com. Petrop. V. io. p. 2. and 6.) 
Che locked jaw, and fome cataleptic fpafms, are refembled by 
this 456 
OCULAR SPECTRA. 
Sect. XL. 9. t. 
this phenomenon ; and from hence we may learn the danger to 
the eye by infpefting very luminous objefts too long a time. 
IX. A quantity ofjlimulus greater than the preceding induces a tem- 
porary paralyfis of the organ of vifon. 
i. Place a circular piece of bright red fdk, about half an inch 
in diameter, on the middle of a iheet of white paper ; lay them 
on the floor in a bright funfhine, and fixing your eyes Readily 
on the centre of the red circle, for three or four minutes, at the 
difl.mce of four or fix feet from the objed, the red filk will grad- 
ually become paler, and finally ceafe to appear red at all. 
2. Similar to thefe are many other animal fads ; as purges, 
opiates, and even poifons, and contagious matter, ceafe to ftim- 
ulate our fyftem, after we have been habituated to their ufe. So 
fome people fleep undifturbed by a clock, or even by a forge 
hammer in their neighbourhood : and not only continued irrita- 
tions, but violent exertions of any kind, are fucceedcd by tempo- 
rary paralyfis. The arm drops down after violent adion, and 
continues for a time ufelefs; and it is probable, that thofe who 
have perifhed fuddenly in fwimming, or in fcating on the ice, 
have owed their deaths to the paralyfis, or extreme fatigue, 
■which fucceeds every violent and continued exertion. 
X. Miscellaneous Remarks. 
There were feme circumftances occurred in making thefe ex- 
periments, which were liable to alter the refults of them, and 
which I (hall here mention fur the afliftance of others, who may 
wifli to repeat them. 
I. OJ direct andinverfe fpt^lra exifingat the fame time ; of recipro- 
cal direct fpchtra ; of a combination of direct and inverfe fpeclra ; 
of a fpe^ral halo ; rules to pre- determine the colours offpePtra. 
a. When an area, about fix inches fquare, of bright pink In- 
dian paper, had been viewed on an area, about a foot fquare, of 
white writing paper, the internal fpedrum in the clofed eye was 
green, being the reverfe fpedrum of the pink paper ; and the 
external fpedrum was pink, being the direct fpedrum of the 
pink paper. The fame circumftance happened when the inter- 
nal area was white, and external one pink ; that is, the internal 
fpedrum was pink, and the external one green. All the fame 
appearances» courted when the pink paper was laid on a black 
hat. 
b. When Sect. XL. io. i. 
OCULAR SPECTRA. 
457 
b. When fix inches fquare of deep violet polilhed paper were 
viewed on a foot fquare of white writing paper, the internal 
fpeftrum was yellow, being the reverfe fpeftrum of the violet 
paper, and the external one was violet, being the direct fpeflrum 
of the violet paper. 
c. When fix inches fquare of pink paper were viewed on a 
foot fquare of blue paper, the internal fpeftrum was blue, and 
the external fpeftrum was pink ; that is, the internal one was 
the direft fpeftrum of the external objeft, and the external one 
was the direft fpeftrum of the internal objeft, inftead of their 
being each the reverfe fpeflrum of the objefts they belong- 
ed to. 
d. When fix inches fquare of blue paper were viewed on a 
foot fquare of yellow paper, the interior fpeftrum became a bril- 
liant yellow, and the exterior one a brilliant blue. The vivaci- 
ty of the fpeftra was owing to their being excited both by the 
ftimulus of the interior and exterior objefts ; fo that the interi- 
or yellow fpeftrum was both the reverfe fpeftrum of the blue 
paper, and the direfl one of the yellow paper; and the exteri- 
or blue fpeftrum was both the reverfe fpeftrum of the yellow 
paper, and the direct one of the blue paper. 
e. When the internal area was only a fquare half-inch of red 
paper, laid on a fquare foot of dark violet paper, the internal 
fpeftrum was green, with a reddilh-blue halo. When the red 
internal paper was two inches fquare, the internal fpeftrum 
was a deeper green, and the external one redder. When the 
internal paper was fix inches fquare, the fpeftrum of it became 
blue, and the fpeflrum of the external paper was red. 
f. When a fquare half-inch of blue paper was laid on a fix- 
inch fquare of yellow paper, the fpeflrum of the central paper 
in the clofed eye was yellow, incircled with a blue halo. On 
looking long on the meridian fun, the dilk fades into a pale blue 
furrounded with a whitilh halo. 
Thefe circumftances, though they very much perplexed the 
experiments till they were inveftigated, admit of a fatisfaflory 
explanation ; for while the rays from the bright internal objeft 
in exp. a. fall with their full force on the centre of the retina, 
and, by fatiguing that part of it, induce the reverfe fpeflrum, 
many fcattered rays, from the fame internal pink paper, fall on 
the more external parts of the retina, but not in fuch quantity 
as to occafion much fatigue, and hence induce the direft fpec- 
truin of the pink colour in thofe parts of the eye. The fame re- 
verfe and direfl fpeftra occur from the violet paper in exp. b. .• 
and in exp. c. the fcattered rays from the central pink paper 
produce a direfl ipeftrum of this colour on the external parts 
Vol. I. L l 1 of 458 
OCULAR SPECTRA. 
Sect. XL. 10.1. 
of the eye, while the fcattered rays from the external blue paper 
produce a direct fpedtrum of that colour on the central part of 
the eye, inftead of thefe parts of the retina falling reciprocally 
into their reverfe fpedtra. In exp. d. the colours being the re- 
verfe of each other, the fcattered rays from the exterior objedt 
falling on the central parts of the eye, and there exciting their 
direct fpedtrum, at the fame time that the rdtina was excited in- 
to a reverfe fpedtrum by the central object, and this direct: and 
reverfe fpedtrum being of fimilar colour, the fuperior brilliancy 
of this fpedtrum was produced. In exp. e. the effect of various 
quantities of ftimulus on the retina, from the different refpec- 
tive fizes of the internal and external areas, induced a fpedtrum 
of the internal area in the centre of the eye, combined of the 
reverfe fpedtrum of that internal area and the direct one of the 
external area, in various (hades of colour, from a pale green to 
a deep blue, with fimilar changes in the fpedtrum of the exter- 
nal area. For the fame reafons, when an internal bright objedt 
was fmall, as in exp. f. inftead of the whole of the fpedtrum of 
the external objedt being reverfe to the colour of the internal 
object, only a kind of halo, or radiation of colour, fimilar to 
that of the internal object, was fpread a little way on the exter- 
nal fpedtrum. For this internal blue area being fo fmall, the 
fcattered rays from it extended but a little way on the image of 
the external area of yellow paper, and could therefore produce 
only a blue halo round the yellow fpedtrum in the centre. 
If any one (hould fufpedt that the fcattered rays from the ex- 
terior coloured objedt do not intermix with the rays from the 
interior coloured object, and thus affedt the central part of the 
eye, let him look through an opaque tube, about two feet in 
length, and an inch in diameter, at a coloured wall of a room 
with one eye, and with the other eye naked ; and he will find, 
that by (hutting out the lateral light, the area of the wall feen 
through a tube appears as if illuminated by the funthine, com- 
pared with the other parts of it; from whence arifes the ad- 
vantage of looking through a dark tube at diftant paintings. 
Hence we may fafely deduce the following rules to deter- 
mine before-hand the colours of all fpedtra. i. The diredt 
fpedtrum without any lateral light is an evanefeent reprefenta- 
tion of its objedt in the unfatigued eye. 2. With fome lateral 
light it becomes of a colour combined of the diredt fpedtrum 
of the central objedt, and of the circumjacent objects, in pro- 
portion to their refpedtive quantity and brilliancy. 3. The re- 
verfc fpedtrum without lateral light is a reprefentation in the 
fatigued eye of the form of its objedls, with fuch a colaur as 
would be produced by all the primary colours, except that of the 
:- objedt. Sect. XL. re. 2. 
OCULAR SPECTRA. 
459 
obje6t. 4. with lateral light the colour is compounded of the 
reverfe fpeftrum of the central objeft, and the dire£t fpeftrum 
of the circumjacent objects, in proportion to their refpeftive 
quantity and brilliancy. 
2. Variation and vivacity of the fpefira occafioned by extraneous 
light. 
The reverfe fpeftrum, as has been before explained, is fimi- 
lar to a colour, formed by a combination of all the primary 
colours, except that with which the eye has been fatigued in 
making the experiment; fo the reverfe fpeftrum of red is fuch 
a green as would be produced by a combination of all the other 
prifmatic colours. Now it muft be obferved, that this reverfe 
fpeftrum of red is therefore the dire<St fpeftrum of a combina- 
tion of all the other prifmatic colours, except the red ; whence, 
on removing the eye from a piece of red filk t® a fheet of white 
paper, the green fpectrum which is perceived, may either be 
called the reverfe fpeftrum of the red filk, or the direft fpec- 
trum of all the rays from the white paper, except the red; for 
in truth it is both. Hence we fee the reafon why it is not eafy 
to gain a direct fpeftrum of any coloured object in the day- 
time, where there is much lateral light, except of very bright 
objects, as of the fetting fun, or by looking^through an opaque 
tube: becaufe the lateral external light falling alfo on the cen- 
tral part of the retina, contributes to induce the reverfe fpec- 
trum, which is at the fame time the direft fpeftrum of that lat- 
eral light, dedufting only the colour of the central cbjeft which 
we have been viewing. And for the fame reafon, it is difficult 
to gain the reverfe fpeftrum, where there is no lateral light to 
contribute to its formation. Thus, in looking through an opaque 
tube on a yellow wall, and doling my eye, without admitting 
any lateral light, the fpeftra were all at firft yellow ; but at 
length changed into blue. And on looking in the fame man- 
ner on red paper, I did at length get a green fpeftrum; but 
they were all at firft red ones: and the fame after looking at a 
candle in the night. 
The reverfe fpeftrum was formed with greater facility when 
the eye was thrown from the object on a Ibeet of white paper, 
or when light was admitted through the clofed eyelids ; becaufe 
not only the fatigued part of the retina was inclined fpontane- 
oufly to fall into motions of a contrary direftion ; but being 
ftill fenfible to all other rays of light except that with which it 
was lately fatigued, was by thefe rays ftimulated at the fame 
time into thofe motions which form the reverfe fpeftrum. 
Hence, 460 
OCULAR SPECTRA. 
Sect. XL. io. 2. 
Hence, when the reverfe fpeflrum of any colour became faint, 
it was wonderfully revived by admitting more light through the 
eyelids, by removing the hand from before them : and hence, 
on covering the clofed eyelids, the fpeftrum would often ceafe 
for a time, till the retina became fenfible to the ftimulus of the 
fmaller quantity of light, and then it recurred. Nor was the 
fpeftrum only changed in vivacity, or in degree, by this admif- 
fion of light through the eyelids ; but it frequently happened, 
after having viewed bright objects, that the fpeftrum in the 
clofed and covered eye was changed into a third fpeftrum, when 
light was admitted through the eyelids : which third fpeftrum 
was compofed of fuch colours as could pafs through the eyelids, 
except thofe of the object. Thus, when an area of half an inch 
diameter of pink paper was viewed on a (beet of white paper in 
the funfhine, the fpeftrum with clofed and covered eyes was 
green ; but on removing the hands from before the clofed eye- 
lids, the fpeftrum became yellow, and returned inftantly again 
to green, as often as the hands were applied to cover the eye- 
lids, or removed from them : for the retina being now infenfible 
to red light, the yellow rays palling through the eyelids in great- 
er quantity than the other colours, induced a yellow fpedtrum ; 
whereas if the fpedtrum was thrown on white paper, with the 
eyes open, it became only a lighter green. 
Though a certain quantity of light facilitates the formation of 
the reverfe fpe&rum, a greater quantity prevents its formation, 
as the more powerful ftimulus excites even the fatigued parts of 
the eye into aftion ; otherwife we Ihould fee the fpeflrum of 
the laft viewed object as often as we turn our eyes. Hence 
the reverfe fpeftra are beft feen by gradually approaching the 
hand near the clofed eyelids to a certain diftance only, which 
muft be varied with the brightnefs of the day, or the energy of 
the fpeclrum. Add to this, that all dark fpe£tra, as black, blue, 
or green, if light be admitted through the eyelids, after they 
have been fome time covered, give reddilh fpeitra, for the rea- 
fons given in Se£t. III. Exp. i. 
From thefe circumftances of the extraneous light coinciding 
with the fpoutaneous efforts of the fatigued retina to produce a 
reverfe fpeclrum, as was obferved before, it is not eafy to gain 
a direct fpeftrum, except of objects brighter than the ambient 
light; fuch as a candle in the night, the fetting fun, or viewing 
a bright objeft through an opaque tube ; and then the reverfe 
fpe6trum is inftantaneoufly produced by the admiflion of fome 
external light; and is as inftantly converted again to the direct 
fpe&rum by the exclufion of it. Thus, on looking at the fet- 
ting fun, on clofmg the eyes, and covering them, a yellow fpec- 
trum Sect. XL. 10.3. 
OCULAR SPECTRA. 
461 
trum is feen, which is the direft fpeftrum of the fetting fun ; 
but on opening the eyes on the Iky, the yellow fpeftrum is im- 
mediately changed into a blue one, which is the reverfe fpec- 
trum of the yellow fun, or the direft fpeftrum of the blue iky, 
or a combination of both. And this is again transformed into 
a yellow one on clofmg the eyes, and fo reciprocally, as quick 
as the motions of the opening and doling eyelids. Hence, 
when Mr. Melvill obferved the fcintillations of the ftar Sirius to 
be fometimes coloured, thefe were probably the direft fpeftrum 
of the blue Iky on the parts of the retina fatigued by the white 
light of the ftar. (Eflays Phyfical and Literary, p. 81. V. 2.) 
When a direft fpeftrum is thrown on colours darker than 
itfelf, it mixes with them ; as the yellow fpeftrum of the fet- 
ting fun, thrown on the green grafs, becomes a greener yellow. 
But when a direft fpeftrum is thrown on colours brighter than 
itfelf, it becomes inftantly changed into the reverfe fpeftrum, 
which mixes with thofe brighter colours. So the yellow fpec- 
trum of the fetting fun thrown on the luminous Iky becomes 
blue, and changes with the colour or brightnefs of the clouds 
on which it appears. But the reverfe fpeftrum mixes with ev- 
ery kind of colour on which it is thrown, whether brighter than 
itfelf or not: thus the reverfe fpeftrum, obtained by viewing a 
piece of yellow filk, when thrown on white paper, was a lucid 
blue green ; when thrown on black Turkey leather, becomes a 
deep violet. And the fpeftrdm of blue filk, thrown on white 
paper, was a light yellow ; on black filk was an obfeure orange ; 
and the blue fpeftrum, obtained from orange-coloured filk, 
thrown on yellow, became a green. 
In thefe cafes the retina is thrown into aftivity or fenfation 
by the ftimulusof external colours, at the fame time that it con- 
tinues the aftivity or fenfation which forms the fpeftra ; in the 
fame manner as the prifmatic colours, painted on a whirling 
top, are feen to mix together. When thefe colours of external 
objefts are brighter than the direft fpeftrum which is thrown 
upon them, they change it into the reverfe fpeftrum, like the 
admiflion of external light on a direft fpeftrum, as explained 
above. When they are darker than the direft fpeftrum, they 
mix it, their weaker Rimulus being infufficient to induce the re- 
verfe fpeftrum. 
3. Variation of fyetlra in ref peel to number, and figure, and re- 
miffion. 
When we look long and attentively at any objeft, the eye can- 
not always be kept entirely motionlefs ; hence, on infpefting a 
cncular 462 
OCULAR SPECTRA. 
Sect. XL. 10. 3. 
circular area o£ red filk placed on white paper, a lucid crefcent 
or edge is feen to librate on one fide or other of the red circle : 
for the exterior parts of the retina fometimes falling on the edge 
of the central filk, and fometimes on the white paper, are lefs 
fatigued with red light than the central part of the retina, which 
is conftantly expofed to it; and therefore, when they fall on the 
edge of the red filk, they perceive it more vividly. Afterwards, 
when the eye becomes fatigued, a green fpeftrum in the form 
of a crefcent is feen to librate on one fide or other of the central 
circle, as by the unfteadinefs of the eye a part of the fatigued 
retina falls on the white paper •, and as by the increafing fatigue 
of the eye the central part of the filk appears paler, the edge on 
which the unfatigued part of the retina occafionally falls will ap- 
pear of a deeper red than the original filk, becaufe it is com- 
pared with the pale internal part of it. M. de Buffon in mak- 
ing this experiment obferved, that the red edge of the filk was 
not only deeper coloured than the original filk ; but, on his re- 
treating a little from it, it became oblong, and at length divided 
into two, which mull have been owing to his obferving it either 
before or behind the point of interfeclion of the two optic ax- 
ifes. Thus, if a pen is held up before a diftant candle, when 
we look intenfely at the pen two candles are feen behind it; 
when we look intenfely at the candle two pens are feen. If 
the fight be unfteady at the time of beholding the fun, even 
though one eye only be ufed, many images of the fun will ap- 
pear, or luminous lines, when the eye is clofed. And as fome 
parts of thefe will be more vivid than others, and fome parts of 
them will be produced nearer the centre of the eye than others, 
thefe will difappear fooner than the others j and hence the num- 
ber and fhape of thefe fpeclra of the fun will continually vary, 
as long as they exift. The caufe of fome being more vivid than 
others, is the unfteadinefs of the eye of the beholder, fo that 
fome parts of the retina have been longer expofed to the fun- 
beams. That fome parts of a complicated fpedtrum fade and 
return before other parts of it, the following experiment evinces. 
Draw three concentric circles ; the external one an inch and a 
half in diameter, the middle one an inch, and the internal one 
half an inch j colour the external and internal areas blue, and 
the remaining one yellow, as in Fig. 4. ; after having looked 
about a minute on the centre of thefe circles, in a bright light, 
the fpe&rum of the external area appears firft in the clofed eye, 
then the middle area, and laftly the central one ; and then the 
central one difappears, and the others in inverted order. If con- 
centric circles of more colours are added, it produces the beau- 
tiful ever changing fpeftrum in Sect. I. Exp. 2. 
From Sect. XL. 10.4. 
OCULAR SPECTRA. 
463 
From hence it would feem, that the centre of the eye produ- 
ces quicker remiffions of fpectra, owing perhaps to its greater 
fenfibility ; that is to its more energetic exertions. Thefe re- 
miffions of fpeClra bear fome analogy to the tremors of the 
hands, and palpitations of the heart, of weak people : and per- 
haps a criterion of the ftrength of any mufcle or nerve may be 
taken from the time it can be continued in exertion. 
4. Variation of fpeclra in refpeB to brilliancy ; the vfibiUty of the 
circulation of the blood in the eye. 
i. The meridian or evening light makes a difference in the 
colours of fome fpeclra ; for as the fun defeends, the red rays, 
which are lefs refrangible by the convex atmofphere, abound in 
-great quantity. Whence the fpeCtrum of the light parts of a 
window at this time, or early in the morning, is red ; and be- 
comes blue either a little later or earlier ; and white in the me- 
ridian day ; and is alfo variable from the colour of the clouds 
or fky which are oppofed to the window. 
2. All thefe experiments are liable to be confounded, if they 
are made too foon after each other, as the remaining fpeCtrum 
will mix with the new ones. This is a very troublefome cir- 
cumftance to painters, who are obliged to look long upon the 
fame colour; and in particular to thofe whofe eyes, from natur- 
al debility, cannot long continue the fame kind of exertion. 
For the fame reafon, in making thefe experiments, the refult be- 
comes much varied if the eyes, after viewing any object, are re- 
moved on other objects for but an inftant of time, before we 
clofe them to view the fpeCtrum -, for the light from the objeCt, 
of which we had only a tranfient view, in the very time of clo- 
fing our eyes aCts as a ftimulus on the fatigued retina ; and for 
a time prevents the defired fpeCtrum from appearing, or mixes 
its own fpeCtrum with it. Whence, after the eyelids are clofed, 
either a dark field, or fome unexpected colours, are beheld for a 
few feconds, before the defired fpeCtrum becomes diftinCtly vifible. 
3. The length of time taken up in viewing an objeCt, of 
which we are to obferve the fpeCtrum, makes a great difference 
in the appearance of the fpeCtrum, not only in its vivacity, but 
in its colour ; as the direCt fpeCtrum of the central objeCt, or of 
the circumjacent ones, and alfo the reverfe fpeCtra of both, with 
their various combinations, as well as the time of their duration 
in the eye, and of their remiffions or alterations, depend upon 
the degree of fatigue the retina is fubjefted to. The Chevalier 
d'Arcy conltruCled a machine by which a coal of fire was 
whirled round in the dark, and found, that when a luminous 
body 464 
OCULAR SPECTRA. 
Sect. XL. 10.4. 
body made revolution in eight thirds of time, is prefented to the 
eye a complete circle of fire ; from whence he concludes, that 
the imprelfion continues on the organ about the feventh part of 
a fecond. (Mem. de 1'Acad. des Sc. 1765.) This, however, 
is only to be confidered as the fhorteft time of the duration of 
thefe dired fpedra ; fince in the fatigued eye both the dired 
and reverfe fpedra, with their intermifhons, appear to take up 
many feconds of time, and feem very variable in proportion to 
the circumftances of fatigue or energy. 
4. It fometimes happens, if the eyeballs have been rubbed 
hard with the fingers, that lucid fparks are feen in quick mo- 
tion amidft the fpedrum we are attending to. This is fimilar 
to the flafhes of fire from a ftroke on the eye in fighting, and is 
refembled by the warmth and glow, which appears upon the fkin 
after fridion, and is probably owing to an acceleration of the ar- 
terial blood into the vefiels emptied by the previous preflure. By 
being accuftomed to obferve fuch fmall fenfations in the eye, it 
is eafy to fee the circulation of the blood in this organ. I have 
attended to this frequently, when I have obferved my eyes more 
than commonly fenfible to other fpedra. The circulation may 
be feen either in both eyes at a time, or only in one of them ; 
for as a certain quantity of light is necefiary to produce this 
curious phenomenon, if one hand be brought nearer the clo- 
fed eyelids than the other, the circulation in that eye will for a 
time difappear. For the eafier viewing the circulation, it is 
fometimes necefiary to rub the eyes with a certain degree 
of force after they are doled, and to hold the breath rather 
longer than is agreeable, which, by accumulating more blood 
in the eye, facilitates the experiment; but in general it may be 
feen diltindly after having examined other fpedra with your 
back to the light till the eyes become weary ; then having cover- 
ed your clofed eyelids for half a minute, till the fpedrum is fa- 
ded away which you were examining, turn your face to the light, 
and removing your hands from the eyelids, by and by again 
{hade them a little, and the circulation becomes curioufly diftind. 
The ftreams of blood are however generally feen to unite, 
which ihews it to be the venous circulation, owing, I fuppofe, 
to the greater opacity of the colour of the blood in thefe vefiels ; 
for this venous circulation is alfo much more eafily feen by the 
microfcope in the tail of a tadpole. 
Variation offpeclra in refpedl to diflinctnefs andJize ; with a new 
way of magnifying objects. 
1. It was before obferved, that when the two colours viewed 
together Sect. XL. 10.5. 
OCULAR SPECTRA. 
465 
together were oppofite to each other, as yellow and blue, red 
and green, &c. according to the table of reflections and tranfmif-. 
fions of light in Sir Ifaac Newton's Optics, B. II. Fig. 3. the 
fpeCtra of thofe colours were of all others the molt brilliant, and 
beft defined ; becaufe they were combined of the reverfe fpec- 
trum of one colour, and of the direCt fpeCtrum of the other. 
Hence, in books printed with fmall types, or in the minute grad- 
uation of thermometers, or of clock-faces, which are to be feen 
at a diftance, if the letters or figures are coloured with orange, 
and the ground with indigo; or the letters with red, and the 
ground with green; or any other lucid colour is ufed for the 
letters, the fpeCtrum of which is fimilar to the colour of the 
ground; fuch letters will be feen much more diftinClly, and 
with lefs confufion, than in black or white : for as the fpeCtrum of 
the letter is the fame colour with the ground on which they are 
feen, the unfteadinefs of the eye in long attending to them will 
not produce coloured lines by the edges of the letters, which is 
the principal caufe of their confufion. The beauty of colours 
lying in vicinity to each other, whofe fpeCtra are thus recipro- 
cally fimilar to each colour, is owing to this greater eafe that 
the eye experiences in beholding them diftinCtly; and it is prob- 
able, in the organ of hearing, a fimilar circumftance may confti- 
tute the pleafure of melody. Sir Ifaac Newton obferves, that 
gold and indigo were agreeable when viewed together ; and 
thinks there may be fome analogy between the fenfations of light 
and found. (Optics, Qu. 14.) 
In viewing the fpeCtra of bright objects, as of an area of red 
filk of half an inch diameter on white paper, it is eafy to mag- 
nify it to tenfold its fize : for if, when the fpeCtrum is formed, 
you ftill keep your eye fixed on the filk area, and remove it a 
few inches further from you, a green circle is feen round the 
red filk ; for the angle now fubtended by the filk is lefs than 
it was when the fpeCtrum was formed, but that of the fpeCtrum 
continues the fame, and our imagination places them at the 
fame diftance. Thus when you view a fpeCtrum on a iheet of 
white paper, if you approach the paper to the eye, you may di- 
minifh it to a point ; and if the paper is made to recede from 
the eye, the fpeCtrum will appear magnified in proportion to the 
diftance. 
I was furprifcd, and agreeably amufed, with the following ex- 
periment. I covered a paper about four inches fquare with 
yellow, and with a pen filled with a blue colour wrote upon the 
middle of it the word BANKS in capitals, as in fig. 5, and fit- 
ting with my back to the fun, fixed my eyes for a minute exadly 
on the centre of the letter N in the middle of the word ; after 
Vol. I. M m m doling 466 
OCULAR SPECTRA. 
Sect. XL. 10. 6. 
clofing my eyes, and (hading them fomewhat with my hand, 
the word was diftin&ly feen in the fpeftrum in yellow letters 
on a blue field ; and then, on opening my eyes on a yellowifh 
wall at twenty feet diftance, the magnified name of BANKS 
appeared written on the wall in golden characters. 
6. Conclufton. 
It was obferved by the learned M. Sauvages (Nofol. Method. 
Cl. VIII. Ord. i.) that the pulfations of the optic artery might 
be perceived by looking attentively on a white wall well illumin- 
ated. A kind of net-work, darker than the other parts of the 
wall, appears and vanifhes alternately with every pulfation. 
This change of the colour of the wall he well afcribes to the 
compreflion of the retina by the diaftole of the artery. The va- 
rious colours produced in the eye by the preflure of the finger, 
or by a (troke on it, as mentioned by Sir Ifaac Newto'n, feem 
like wife to originate from the unequal preflure on various parts 
of the retina. Now as Sir Ifaac Newton has (hewn, that all 
the different colours are reflected or tranfmitted by the laminae 
of foap bubbles, or of air, according to their different thicknefs 
or thinnefs, is it not probable, that the effeCt of the a&ivity of the 
retina may be to alter its thicknefs or thinnefs, fo as better to 
adapt it to reflect or tranfmit the colours which (limulate it into 
aftion ? May not mufcular fibres exilt in the retina for this pur- 
pofe, which may be lefs minute than the locomotive mufclesof mi- 
crofcopic animals ? May not thefe mufcular actions of the ret- 
ina coriftitute the fenfation of light and colours ; and the volun- 
tary repetitions of them, when the objeCt is withdrawn, confti- 
tutc our memory of them ? And laftly, may not the laws of the 
fenfations of light, here invelligated, be applicable to all our oth- 
er fenfes, and much contribute to elucidate many phenomena of 
animal bodies both in their healthy and difeafed (late ; and thus 
render this inveftigation well worthy the attention of the phyfi- 
cian, the metaphyfician, and the natural philofopher ? 
November i, 1785. 
Bum, Liber ! aftra petis volifans trepidantibus alis, 
Irruis immemori, parvula gutta, inari. 
Me quoque, me currentc rota revolubilis aetas 
Volverit in tenebras,-i, Liber, ipfe fequor. 
END Or THE FIRST PART. ZOONOMI A; 
OR, 
THE LAWS OF ORGANIC LIFE, 
*. 
PART 111. 
CONTAINING 
THE ARTICLES OF THE MATERIA MEDICA, 
t 
WITH AN ACCOUNT OF THE 
OPERATION OF MEDICINES. 
IN VIVUM CORPUS 
ACUNT MEDICAMENTA. PREFACE. 
The Materia Medic a includes all thofe fubftan- 
ces, which may contribute to the reftoration of health. 
Thefe may be conveniently diftributed under feven ar- 
ticles according to the diverfity of their operations. 
i. Nutrientia, or thofe things which preferve 
in their natural ftate the due exertions of all the irrita- 
tive motions. 
2. Incitantia, or thofe things which increafe the 
exertions of all the irritative motions. 
3. Secernentia, or thofe things which increafe 
the irritative motions, which conftitute fecretion. 
4. Sorbentia, or thofe things which increafe the 
irritative motions, which conftitute abforption. 
5. Invertentia, or thofe things which invert the 
natural order of the fucceflive irritative motions. 
6. Revertentia, or thofe things which reftore 
the natural order of the inverted irritative motions. 
7. Tor pent 1 a. 4 
PREFACE. 
7. Tor pen tia, thofe things which diminifh the 
exertions of all the irritative motions. 
♦ 
It is neceffary to apprize the reader, that in the 
following account of the virtues of Medicines their 
ufual dofes are always fuppofed to be exhibited; and 
the patient to be expofed to the degree of exterior 
heat, which he has been accuftomed to, (where the 
contrary is not mentioned), as any variation of either of 
thefe circumftances varies their effects. 
ARTICLES ARTICLES 
OF THE 
MATERIA MEDIC A. 
Art. I. 
NUTRIENTIA. 
I. i. Those things, which preferve in the natural ftate the 
due exertions of all the irritative motions, are termed nutrien- 
tia ; they produce the growth, and reftore the wafte, of the fyf- 
tem. Thefe confift of a variety of mild vegetable and animal 
fubftances, water, and air. 
2. Where ftronger ftimuli have been long ufed, they become 
neceflary for this purpofe, as muftard, fpice, fait, beer, wine, 
vinegar, alcohol, opium. Which however, as they are unnat- 
ural ftimuli, and difficult to manage in refpeCt to quantity, are 
liable to fhorten the fpan of human life, fooner rendering the 
fyftem incapable of being (Emulated into action by the nutrien- 
tia. See SeCt. XXXVII. 4. On the fame account life is (hort- 
er in warmer climates than in more temperate ones. 
IL Observations on the Nutrientia. 
I. i. The flefli of animals contains more nourifhment, and 
{Emulates our abforbent and fecerning veflels more powerfully, 
than the vegetable productions, which we ufe as food ; for the 
carnivorous animals can faft longer without injury than the 
graminivorous ; and we feel ourfelves warmer and Itronger af- 
ter a meal of flefh than of grain. Hence in difeafes attended with 
cold extremities and general debility this kind of diet is prefer- 
red ; as in rickets, dropfy, fcrofula, and in hyfteric and hypochon- 
driac cafes, and to prevent the returns of agues. Night not 
flefh 6 
NUTRIENTIA. 
Art. I. 2. 1. 2. 
flefh in fmall quantities bruifcd to a pulp be more advantageouf- 
ly ufed in fevers attended with debility than vegetable diet ? 
That flefh, which is of the darkeft colour, generally contains 
more nourifhment, and ftimulates our veffels more powerfully, 
than the white kinds. The flefh of the carnivorous and pifeiv- 
orous animals is fo ftimulating, that it feldom enters into the 
food of European nations, except the fwine, the Soland goofe 
(Pelicanus Baffanus), and formerly the fwan. Of thefe the 
fwine and the fwan are fed previoufly upon vegetable aliment ; 
and the Soland goofe is taken in very fmall quantity, only as a 
whet to the appetite. Next to thefe are the birds, that feed up- 
on infers, which are perhaps the moft ftimulating and the moft 
nutritive of our ufual food. 
It is faid that a greater quantity of volatile alkali can be ob- 
tained from this kind of flefh, to which has been afcribed its 
ftimulating quality. But it is more probable, that frefh flefh 
contains only the elements of volatile alkali. 
2. Next to the dark coloured flefh of animals, the various tribes 
of fhell-fifh feem to claim their place, and the wholefdhie kinds 
of mufhrooms, which mull be efteemed animal food, both for 
their alkalefcent tendency, their ftimulating quality,and the quan- 
tity of nourifhment, which they afford; as oyfters, lobfters, crab- 
fifh, fhrimps; mufhrooms ; to which perhaps might be added 
fome of the fifh without fcales ; as the eel, barbolt, tench, fmelt, 
turbot, turtle. 
The flefh of many kinds of fifh, when it is fuppofed to have 
undergone a beginning putrefaction, becomes luminous in the 
dark. This feems to fhew a tendency in the phofphorus to ef- 
capc, and combine with the oxygen of the atmofphere; and 
would hence fhew, that this kind of flefh is not fo perfectly an- 
imalized as thofe before mentioned. This light, as it is fre- 
quently feen on rotten wood, and fometimes on veal, which has 
been kept too long, as I have been told, is commonly fuppofed 
to have its caufe from putrefaCtion; but is neverthelefs moft 
probably of phofphoric origin, like that feen in the dark on 
oyfter-fhells, which have previoufly been ignited and afterwards 
expofed to the fitmfhine, and on the Bolognian ftone. See Bo- 
tan. Gard. Vol. I. Cant. I. line 182, the note, and additional 
note X. 
3. The flefh of young animals, as of lamb, veal, and fucking- 
pigs, fupplies us with a ftill lefs ftimulating food. The broth 
of thefe is faid to become four, and continues fo a confiderable 
time before it changes into putridity ; fo much does their flefh 
p irtake of the chemical properties of the milk, with which thefe 
animals are nourifhed. 
4. The Art. I. 1. 4. 2. 
NUTRIENTIA. 
7 
4- The white meats, as of turkey, partridge, pheafant, fowl, 
with their eggs, feem to be the next in mildnefs; and hence are 
generally firft allowed to convalefcents from inflammatory dif- 
eafes. 
5. Next to thofe fliould be ranked the white river-fifli, which 
have fcales, as pike, perch, gudgeon. 
IL 1. Milk unites the animal with the vegetable fource of our 
nourifhment, partaking of the properties of both. As it con- 
tains fugar, and will therefore ferment and produce a kind of 
wine or fpirit, which is a common liquor in Siberia j or will run 
into an acid by Ample agitation, as in the churning of cream ; 
and laftly, as it contains coagulable lymph, which will undergo 
the procefs of putrefaction like other animal fubftances, as in old 
cheefe. 
2. Milk may be feparated by reft or by agitation into cream, 
butter, butter-milk, whey, curd. The cream is eafier of digeftion 
to adults, becaufe it contains lefs of the coagulum or cheefy part, 
and is alfo more nutritive. Butter confifting of oil between an 
animal and vegetable kind contains ftill more nutriment, and in 
its recent ftate is not difficult of digeftion if taken in moderate 
quantity. See Art. I. 2. 3. 2. Buttermilk if it be not bitter is 
an agreeable and nutritive fluid; if it be bitter it has fome pu- 
trid parts of the cream in it, which had been kept too long ; 
but is perhaps not lefs wholefome for being four to a certain 
degree : as the inferior people in Scotland choofe four milk in 
preference to Ikimmed milk before it is become four. Whey is 
the leaft nutritive and eafieft of digeftion. And in the fpring 
of the year, when the cows feed on young grafs, it contains fo 
much of vegetable properties, as to become a falutary potation, 
when drunk to about a pint every morning, to thofe who du- 
ring the winter have taken too little vegetable nourifhment, and 
who are thence liable to bilious concretions. 
3. Cheefe is of various kinds, according to the greater or lefs 
quantity of cream, which it contains, and according to its age. 
Thofe cheefes, which are eafieft broken to pieces in the mouth, 
are generally eafieft of digeftion, and contain moft nutriment. 
Some kinds of cheefe, though flow of digeftion, are alfo flow in 
changing by chemical procefles in the ftomach, and therefore 
will frequently agree well with thofe, who have a weak digeftion j 
as I have feen toafted cheefe vomited up a whole day after it 
was eaten without having undergone any apparent change, or 
given any uneafinefs to the patient. It is probable a portion of 
fugar, or pf animal fat, or of the gravy of boiled or roafted meat, 
mixed with cheefe at the time of making it, might add to its 
pleafant and nutritious quality. 
Vol. I. N n n ( 4. The 8 
NUTRIENTIA. 
Art. I. 2. 2. 4. 
4- The reafon why autumnal milk is fo much thicker or co- 
agulable than vernal milk, is not eafy to underftand ; but as new 
milk is in many refpedls fimilar to chyle, it .may be confidered 
as food already in part digefted by the animal it is taken from, 
and thence fupplies a nutriment of eafy digeftion. As it requires 
to be curdled by the gaftric acid, before it can enter the lac- 
teals, as is feen in the ftomachs of calves, it feems more fuita- 
ble to children, whofe ftomachs abound more with acidity, than 
to adults; but neverthelefs fupplies good nourifhment to many 
of the latter, and particularly to thofe, who ufe vegetable food, 
and whofe ftomachs have not been much accuftomed to the un- 
natural ftimulus of fpice, fait, and fpirit. See Clafs I. i. 2. 5. 
III. 1. The feeds, roots, leaves, and fruits of plants, confti- 
tute the greateft part of the food of mankind ; the refpeftive 
quantities of nourifhment which thefe contain, may perhaps be 
eftimated from the quantity of ftarch, or of fugar, they can be 
made to produce : in farinaceous feeds, the mucilage feems grad- 
ually to be converted into ftarch, while they remain in our gra- 
naries ; and the ftarch by the germination of the young plant, 
as in making malt from barley, or by animal digeftion, is 
converted into fugar. Hence old wheat and beans contain 
more ftarch than new ; and in our ftomachs other vegetable and 
animal materials are converted into fugar; which conftitutes in 
all creatures a part of their chyle. 
Hence it is probable, that fugar is the moft nutritive part of 
vegetables; and that they are more nutritive, as they are con- 
vertible in greater quantity into fugar by the power of digeftion ; 
as appears from fugar being found in the chyle of all animals, 
and from its exifting in great quantity in the urine of patients 
in the diabetes, of which a curious cafe is related in Secft. XXIX. 
4. where a man labouring under this malady ate and drank an 
enormous quantity, and fometimes voided fixteen pints of water 
in a day, with an ounce of fugar in each pint. 
The nutritive quality of fugar is not only (hewn by the (laves 
in Jamaica, and other animals, becoming fatter in the fugar 
harveft, though they are forced to labour more, but alfo from 
the many inftances of its nourifhing for fome years very old 
people, who could take little of any other food. Many of 
which cafes are recorded in Dr. Mofely's Treatife on Sugar, 
and three I have myfelf witnefled. 
Nor is this to be wondered at, as it conftitutes a part of the 
chyle both of vegetables and animals ; which only feem to dif- 
fer from each other in this circumftance, that the chyle of veg- 
etables eonfifts principally of fugar and mucilage diflolved in 
water; as the juice extracted from birch and maple-trees in 
the Art. I. 2. 3. 2. 
NUTRIENTIA. 
9 
the vernal months, and is therefore tranfparent and colourlefs ; 
but the chyle of animals alfo contains oil, mixed with the fugar 
and mucilage and water, which gives it its milky appearance, 
owing to its imperfect folution. 
2. Oil, when mixed with mucilage or coagulable lymph, as 
in cream or new milk, is eafy of digeftion, and conftitutes prob- 
ably the moft nutritive part of animal diet; as oil is another 
part of the chyle of all animals. As thefe two materials, fugar 
and butter, contain much nutriment under a fmall volume, and 
readily undergo fome chemical change fo as to become acid or 
rancid ; they are liable to difturb weak ftomachs, when taken 
in large quantity, more than aliment, which contains lefs nour- 
ifhment, and is at the fame time lefs liable to chemical changes; 
becaufe the chyle is produced quicker than the torpid lafteals 
can abforb it, and thence undergoes a further chemical procefs. 
Sugar and butter therefore are not fo eafily digefted, when ta- 
ken in large quantity, as thofe things, which contain lefs nutri- 
ment ; hence, where the flomach is weak, they mult be ufed in 
lefs quantity. But the cullom of fome people in reftraining 
children entirely from them, is depriving them of a very whole- 
fome, agreeable, and fubftantial part of their diet. Honey, 
manna, fap-juice, are different kinds of lefs pure fugar. 
3. All the efculent vegetables contain a bland oil, or mucil- 
age, or flarch, or fugar, or acid ; and, as their ftimulus is mod- 
erate, are properly given alone as food in inflammatory difeaf- 
es; and mixed with milk conftitute the food of thoufands. 
Other vegetables poflefs various degrees and various kinds of 
ftimulus; and to thefe we are beholden for the greater part of 
our Materia Medica, which produce naufea, ficknefs, vomiting, 
catharfis, intoxication, inflammation, and even death, if unfkil- 
fully adminillered. 
The acrid or intoxicating, and other kinds of vegetable juices, 
fuch as produce ficknefs, or evacuate the bowels, or fuch even 
as are only difagreeable to the palate, appear to be a part of the 
defence of thofe vegetables, which poflefs them, from the aflaults 
of larger animals or of infefts. As mentioned in the Botanic 
Garden, Part II. Cant. I. line 161, note. This appears in a 
forcible manner from the perufal of fome travels, which have 
been publifhed of thofe unfortunate people, who have fuffered 
fliipwreck on uncultivated countries, and have with difficul- 
ty found food to fubfift, in otherwife not inhofpitable climates. 
4. As thefe acrid and intoxicating juices generally relide in 
the mucilage, and not in the ftarch of many roots, and feeds, 
according to the obfervation of M. Parmentier, the wholefome 
or nutritive parts of fome vegetables may be thus feparated from 
the 10 
NUTRIENTIA. 
Art. I. 2. 3. 5. 
the medicinal parts of them. Thus if the root of white briony 
be rafped into cold water, by means of a bread-grater made of 
a tinned iron plate, and agitated in it, the acrid juice of the root 
along with the mucilage will be diflblved, or fwim, in the water; 
while a ftarch perfectly wholefome and nutritious will fubfide, 
and may be ufed as food in times of fcarcity. 
M. Parmentier further obferves, that potatoes contain too 
much mucilage in proportion to their ftarch, which prevents them 
from being converted into good bread. But that if the ftarch 
be colle&ed from ten pounds of raw potatoes by grating them 
into cold water, and agitating them, as above mentioned ; and 
if the ftarch thus procured be mixed with other ten pounds of 
boiled potatoes, and properly fubje&ed to fermentation like 
wheat flour, that it will make as good bread as the fineft wheat. 
Good bread may alfo be made by mixing wheat-flour with 
boiled potatoes. Eighteen pounds of wheat-flour are faid to 
make twenty-two pounds and a half of bread. Eighteen pounds 
of wheat-flour mixed with nine pounds of boiled potatoes, are 
faid to make twenty-nine pounds and a half of bread. This 
difference of weight muft arife from the difference of the previ- 
ous drynefs of the two materials. The potatoes might proba- 
bly make better flour, if they were boiled in fteam, in a clofe 
veflel, made fome degrees hotter than common boiling water. 
Other vegetable matters may be deprived of their too great 
acrimony by boiling in water, as the great variety of the cab- 
bage, the young tops of white briony, water-creffes, afparagus, 
with innumerable roots, and fome fruits. Other plants have 
their acrid juices or bitter particles diminifhed by covering 
them from the light by what is termed blanching them, as the 
ftems and leaves of cellery, endive, fea-kale. The former 
method either extracts or decompofes the acrid particles, and 
the latter prevents them from being formed. See Botanic 
Garden, Vol. I. additional note XXXIV. on the Etiolation of 
vegetables. 
5. The art of cookery, by expofing vegetable and animal 
fubftances to heat, has contributed to increafe the quantity of 
the food of mankind by other means befides that of deftroying 
their acrimony. One of thefe is by converting the acerb juices 
of fome fruits into fugar, as in the baking of unripe pears, and 
the bruifing of unripe apples ; in both which lituations the life 
of the vegetable is deftroyed, and the convcrfion of the harfh 
juice into a fweet one muft be performed by a chemical procefs ; 
and not by a vegetable one only, as the germination of barley in 
making malt has generally been fuppofed. 
Some circumftances, which feem to injure the life of feveral 
fruits. Art. I. 2. 3. 5. 
NUTRIENTIA. 
11 
fruits, feem to forward the faccharine procefs of their juices. 
Thus if fome kinds of pears are gathered a week before they 
would ripen on the tree, and are laid on a heap and covered, 
their juice becomes fweet many days fooner. The taking off 
a circular piece of the bark from a branch of a pear-tree caufes 
the fruit of that branch to ripen fooner by a fortnight, as I have 
more than once obferved. The wounds made in apples by in- 
fects occafion thofe apples to ripen fooner ; caprification, or the 
piercing of figs, in the ifland of Malta, is faid to ripen them 
fooner ; and I am well informed, that, when bunches of grapes 
in this country have acquired their expected fize, if the ftalk of 
each bunch be cut half through, they will fooner ripen. 
The germinating barley in the malt-houfe I believe acquires 
little fweetnefs, till the life of the feed is deftroyed, and the fac- 
charine procefs then continued or advanced by the heat in dry- 
ing it. Thus in animal digeftion, the fugar produced in the 
ftomach is abforbed by the lafteals as fall as it is made, other- 
wife it ferments, and produces flatulency ; fo in the germina- 
tion of barley in the malt-houfe, fo long as the new plant -lives, 
the fugar, I fuppofe, is abforbed as faft as it is made ; but that, 
which we ufe in making beer, is the fugar produced by a chem- 
ical procefs after the death of the young plant, or which is made 
more expeditioufly, than the plant can abforb it. 
It is probably this faccharine procefs, which obtains in new 
hayflacks too haftily, and which by immediately running into 
fermentation produces fo much heat as to fet them on fire. 
The greateft part of the grain, or feeds, or roots, ufed in the 
diftillcries, as wheat, canary feed, potatoes, are not I believe 
previoufly fubjefted to germination, but are in part by a chemi- 
cal procefs converted into fugar, and immediately fubje€led to 
vinous fermentation ; and it is probable a procefs may fome- 
time be difcovered of producing fugar from ftarch or meal; and 
of feparating it from them for domeflic purpofes by alcohol, 
which diflblves fugar but not mucilage ; or by other means. 
Another method of increafing the nutriment of mankind by 
cookery, is by diflblving cartilages and bones, and tendons, and 
probably fome vegetables, in fleam or water at a much higher 
degree of heat than that of boiling. This is to be done in a 
clofe veflel, which is called Papin's digefler ; in which, it is 
faid, that water may be made redhot, and will then diflblve all 
animal fubflances; and might thus add to our quantity of food 
in times of fcarcity. This veflel fhould be made of iron, and 
fhould have an oval opening at top, with an oval lid of iron 
larger than the aperture ; this lid fhould be flipped in endways, 
when the veflel is filled, and then turned, and raifed by a fcrew 
above 12 
NUTRIENTIA. 
Art. I. 2. 3. 6. 
above it into contact with the under edges of the aperture. 
There fhould alfo be a fmall tube or hole covered with a weight- 
ed valve to prevent the danger of burfting the digefter. 
Where the powers of digeftion are weakened, broths made 
by boiling animal and vegetable fubftances in water afford a nu- 
triment ; though I fuppofe not fo great as the flefh and vegeta- 
bles would afford, if taken in their folid form, and mixed with 
faliva in the act of maftication. The aliment thus prepared 
fhould be boiled but a fhort time, nor fhould be fuffered to con- 
tinue in our common kitchen-utenfils afterwards, as they are 
lined with a mixture of half led and half tin, and are therefore 
unwholefome, though the copper is completely covered. And 
thofe foups, which have any acid or wine boiled in them, un- 
lefs they be made in filver, or in china, or in thofe pot-vef- 
fels, which are not glazed by the addition of lead, are truly poi- 
fonous ; as the acid, as lemon-juice or vinegar, when made hot, 
erodes or diffolves the lead and tin lining of the copper-veffels, 
and the leaden glaze of the porcelain ones. Hence, where fil- 
ver cannot be had, iron veffels are preferable to tinned copper 
ones; or thofe made of tinned iron-plates in the common tin- 
fhops, which are faid to be covered with pure or block tin. 
6. Another circumftance, which facilitates the nourifhment 
of mankind, is the mechanic art of grinding farinaceous feeds 
into powder between mill-ftones ; which may be called the ar- 
tificial teeth of fociety. It is probable, that fome foft kinds of 
wood, efpecially when they have undergone a kind of fermenta- 
tion, and become of loofer texture, might be thus ufed as food 
in times of famine. 
Nor is it improbable, that hay, which has been kept in ftacks, 
fo as to undergo the faccharine procefs, may be fo managed by 
grinding and by fermentation with yeaft like bread, as to ferve 
in part for the fuftenance of mankind in times of great fcarcity. 
Dr. Prieflley gave to a cow for fome time a ftrong infufion of 
hay in large quantity for her drink, and found that (lie produ- 
ced during this treatment above double the quantity of milk. 
Hence if bread cannot be made from ground hay, there is great 
reafon to fufpeft, that a nutritive beverage may be thus prepared 
either in its faccharine ftate, or fermented into a kind of beer. 
In times of great fcarcity there are other vegetables, which 
though not in common ufe, would moft probably afford whole- 
fome nourifhment, either by boiling them, or drying and grinding 
them, or by both thofe proceffes in fucceffion. Of thefe are per- 
haps the tops and the bark of all thofe vegetables, which are 
armed with thorns or prickles, as goofeberry trees, holly, gorfe, 
and perhaps hawthorn. The inner bark of the elm tree makes 
a Art. I. 2. 3. 7. 
NUTRIENTIA. 
13 
a kind of gruel. And the roots of fern, and probably of very 
many other roots, as of grafs and of clover taken up in winter, 
might yield nourifhment either by boiling or baking, and fepa- 
rating the fibres from the pulp by beating them ; or by getting 
only the ftarch from thofe, which poffefs an acrid mucilage, as 
the white briony. And the alburnum of perhaps all trees, and 
efpecially of thofe which bleed in fpring, might produce a fac- 
charine and mucilaginous liquor by-boiling it in the winter or 
fpring. 
7. However the arts of cookery and of grinding may in- 
creafe or facilitate the nourifhment of mankind, the great fource 
of it is from agriculture. In the favage ftate, where men live 
folely by hunting, I was informed by' Dr. Franklin, that there 
was feldom more than one family exifted in a circle of five miles 
diameter; which in a ftate of pafturage would fupport fome 
hundred people, and in a ftate of agriculture man^ thoufands. 
The art of feeding mankind on fo fmall a grain as wheat, which 
feems to have been difcovered in Egypt by the immortal name 
of.Ceres, fhewed greater ingenuity than feeding them with the 
large roots of potatoes, which feem to have been a difcovery of 
ill-fated Mexico. 
This greater production of food by agriculture than by paftur- 
age, (hews that a nation nourifhed by animal food will be lefs nu- 
merous than if nourifhed by vegetable; and the former will there- 
fore be liable, if they are engaged in war, to be conquered by 
the latter, as Abel was (lain by Cain. This is perhaps the only 
valid argument againft inclofing open arable fields. The great 
production of human nourifhment by agriculture and pafturage 
evinces the advantage of fociety over the favage ftate ; as the 
number of mankind becomes increafed a thoufand fold by the 
arts of agriculture and pafturage ; and their happinefs is proba- 
bly under good governments improved in as great a proportion, 
as they become liberated from the hourly fear of beafts of prey, 
from the daily fear of famine, and of the occafional incurfions 
of their cannibal neighbours. 
But pafturage cannot exift without property both in the foil, 
and the herds which it nurtures ; and for the invention of arts, 
and production of tools necefl'ary to agriculture, fome muft think, 
and others labour ; and as the efforts of fome will be crowned 
with greater fuccefs than that of others, an inequality of the 
ranks of fociety muft fucceed ; but this inequality of mankind in 
the prefent ftate of the world is too great for the purpofes of pro- 
ducing the greateft quantity of human nourifhment, and the 
greateft fum of human happinefs ; there fhould be no flavery at 
•ne end of the chain of fociety, and no defpotifm at the other.- 
By 14 
NUTRIENTIA. 
Art. I. 2. 4. 1. 
By the future improvements of human reafon fuch govern- 
ments may poflibly hereafter be eftablilhed, as may a hundred- 
fold increafe the numbers of mankind,and a thoufand-fold their 
happinefs. 
IV. i. Water muft be confidered as a part of our nutriment, 
becaufe fo much of it enters the compofition of our folids as 
well as of our fluids ; and becaufe vegetables are now believed to 
draw almoft the whole of their nourilhment from this fource. 
As in them the water is decompofed, as it is perfpired by them 
in the funlhine, the oxygen gas increafes the quantity and the 
purity of the atmofphere in their vicinity, and the hydrogen 
feems to be retained, and to form the nutritive juices, and con- 
fequent fecretions of refin, gum, wax, honey, oil, and other veg- 
etable productions. See Botanic Garden, Part I. Cant. IV. 
line 25, note. It has however other ufes in the fyllem, befides 
that of a nouVilhing material, as it dilutes our fluids, and lubri- 
cates our folids; and on all thefe accounts a daily fupply of it is 
required. 
2. River-water is in general purer than fpring-water; as the 
neutral faits walhed down from the earth decompofe each other, 
except perhaps the marine fait; and the earths, with which 
fpring-water frequently abounds, is precipitated; yet it is not 
improbable, that the calcareous earth diflblved in the water of 
many fprings may contribute to our nourilhment, as the water 
from fprings, which contain earth, is faid to conduce to enrich 
thofe lands, which are flooded with it, more than river water. 
The Chinefe are faid, by Sir G. Staunton, to purify the water 
of fome muddy rivers or canals, by ftirring them with a hollow 
cane full of fmall holes, in the tube of which are enclofed fome 
pieces of alum. And the bakers in London aflert, that one ufe 
of alum is to clear the New River water, and thus to render 
their bread whiter. Where any volatile alkali is mixed with 
water, as often happens from the liable dung and other ordure 
of populous towns, it will be converted to vitriolic ammoniac by 
a folution of alum ; and calcareous earth may be converted into 
gypfum, and fubfide along with the earth of the alum. See 
Clafs II. 1. 6. 16. 
3. Many arguments feem to Ihew, that calcareous earth con- 
tributes to the nourilhment of animals and vegetables. Firft 
becaufe calcareous earth conftitutes a conliderable part of them, 
and muft therefore either be received from without, or formed 
by them, or both, as milk, when taken as food by a la£lefcent 
woman, is decompofed in the ftomach by the procefs of digef- 
tion, and again in part converted into milk by the pectoral glands. 
Secondly, becaufe from the analogy of all organic life, whatever 
has Art. T. 2.4. 3. 
NUTRIENTIA. 
15 
has compofed a part of a vegetable or animal may again after 
its chemical folution become a part of another vegetable or an- 
imal, fuch is the general tranfmigration of matter. And thirdly, 
becaufe the great ufe of lime in agriculture on almoft all kinds 
of foil and fituation cannot be fatisfaftorily explained from its 
chemical properties alone. Though thefe may alfo in cetrain 
foils and fituations have confiderable effect. 
The chemical ufes of lime in agriculture niay be, i. from its 
deftroying in a Ihort time the cohefion of dead vegetable fibres, 
and thus reducing them to earth, which otherwife is effetfted by 
a flow procefs either by the confumpdon of infedts or by a, 
gradual putrefaction. Thus I am informed that a mixture of 
lime with oak bark, after the tanner has extracted from it what- 
ever is foluble in water, will in two or three months reduce it 
to a fine black earth, which, if only laid in heaps, it would re- 
quire as many years to effeCt by its own fpontaneous fermenta- 
tion or putrefaClion. This effeCt of lime muft be particularly ad- 
vantageous to newly enclofed commons when firft broken up. 
Secondly, lime for many months continues to attraCt moifture 
from the air or earth, which it deprives I fuppofe of carbonic 
acid, and then fuffers it to exhale again, as is feen on the plaf- 
feted walls of new houfes. On this account it muft be advan- 
tageous when mixed with dry or fandy foils, as it attraCls moif- 
ture from the air above or the earth beneath, and this moifture 
is then abforbed by the lymphatics of the roots of vegetables. 
Thirdly, by mixing lime with clays it is believed to make them 
lefs cohefive, and thus to admit of their being more eafily pen- 
etrated by vegetable fibres. A mixture of lime with clays de- 
itroys their fuperabundancy of acid, if fuch exifts, and by unit- 
ing with it converts it into gypfum or alabafter. And laftly, 
frefli lime deftroys worms, fnails, and other infects, with which 
it happens to come in contaCt. , 
Yet do not all thefe chemical properties feeni to account for 
the great ufes of lime in almoft all foils and fituations, as it con- 
tributes fo much to the melioration of the crops, as well as to 
their increafe-and quantity. Wheat from land well limed is 
believed by farmers, millers, and bakers, to be, as they fuppofe, 
thinner Ikinned; that is, it turns out more and better flour ; 
which I fuppofe is owing to its containing more ftarch and 
lefs mucilage. In rcfpeQ to grafs-ground I am informed, that 
if a fpadeful of lime be thrown on a tuflbek, which horfes or 
cattle have refufed to touch for years, they will for many fuc- 
ceeding feafons eat it quite clofe to the ground. 
One property of lime is not perhaps yet well underftood, I 
mean its producing fo much heat, when it is mixed with water, 
Vol. I. O o o which 16 
NUTRIENTIA. 
Art. I. 2. 4. 4, 
which may be owing to the elementary fluid of heat confolidated 
in the lime. It is the Ream occasioned by this heat, when water 
is fprinkled upon lime, if the water be not in too great quan- 
tity or too cold, which breaks the lime into fuch fine powder as 
almoft to become fluid, which cannot be effe&ed perhaps by 
any other means, and which I fuppofe muft give great prefer- 
ence to lime in agriculture, and to the folutions of calcareous 
earth in water, over chalk or powdered lime-ftone, when fpread 
upon the land. 
4. It was formerly believed that waters replete with calcare- 
ous earth, fuch as incruft the infide of tea-kettles, or are faid to 
petrify mofs, were liable to produce or to increafe the ftone in 
the bladder. This miftaken idea has lately been exploded by 
the improved chemiftry, as no calcareous earth, or a very minute 
quantity, was found in the calculi analyfed by Scheele and Berg- 
man. The waters of Matlock and of Carhbad, both which cover 
the mofs, which they pafs through, with a calcareous cruft, are 
fo far from increafing the ftone of the bladder or kidneys, that 
thofe of Carlfbad are celebrated for giving relief to thofe labour- 
ing under thefe difeafes. Philof. Tranf. Thofe of Matlock 
are drunk in great quantities without any fufpicion of injury ; 
and I well know a perfon who for above ten years has drunk 
about two pints a day of cold water from a fpring, which very 
much incrufts the veffcls, it is boiled in, with calcareous earth, 
and affords a copious calcareous fediment with a folution of fait 
of tartar, and who enjoys a ftate of uninterrupted health. 
V. 1. As animal bodies confift much both of oxygen and 
azote, which make up the compofition of atmofpheric air, thefe 
{bould be counted amongft nutritious fubftances. Befides that 
by the experiments of Dr. Prieftley it appears, that the oxygen 
gains admittance into the blood through the moift membranes 
of the lungs ; and feems to be of much more imrpeditte confe- 
quence to the prefervation of our lives than the other kinds of 
nutriment above fpecified. 
As the bafis of fixed air, or carbonic acid gas, is carbone, 
which alio conftitutes a great part both of vegetable and animal 
bodies ; this air ihould likewife be reckoned amongft nutritive 
fubftances. Add to this, that when this carbonic acid air is 
fwallowed, as it efcapes from beer or cyder, or when water is 
charged with it as detruded from limeftone by vitriolic acid, it 
affords an agreeable fenfation both to the palate and ftomach, 
and is therefore probably nutritive. 
The immenfe quantity of carbone and of oxygen which con- 
ftitute fo great a part of the limeftone countries is almoft be- 
vond conception, and, as it has been formed by animals, may 
again Art. I. 2. 6. 1. 
NUTRIENTIA. 
17 
again become a part of them, as well as the calcareous matter 
with which they are united. Whence it may be conceived, 
that the waters, which abound with limeftone in folution, may 
fupply nutriment both to animals and to vegetables, as mention- 
ed above. 
VI. i. The manner, in which nutritious particles are fub- 
ftituted in the place of thofe, which are mechanically abraded, 
or chemically decompofed, or which vanilh by animal abforp- 
tion, muft be owing to animal appetency, as defcribed in Seft. 
XXXVII. 3. and is probably fimilar to the procefs of inflamma- 
tion, which produces new veflels and new fluids; or to that 
which conftitutes the growth of the body to maturity. Thus 
the granulations of new flefh to repair the injuries of wounds 
are vifible to the eye ; as well as the callous matter, which ce- 
ments broken bones; the calcareous matter, which repairs in- 
jured fhail-fhells , and the threads, which are formed by filk- 
worms and fpiders ; which are all fecreted in a fofter ftate, and 
harden by exGecation, or by the Coptadl of the air, or by abforp- 
tion of their more fluid parts. 
Whether the materials, which thus fupply the wafte of the 
fyftem, can be given any other way than by the ftomach, fo as 
to preferve the body for a length of time, is worth our inquiry ; 
as cafes fometimes occur, in which food cannot be introduced 
into the ftomach, as in obftruclions of the oefophagus, inflam- 
mations of the throat, or in hydrophobia ; and other cafes are 
not unfrequent in which the power of digeftion is nearly or to- 
tally deftroyed, as in anorexia epileptica, and in many fevers. 
In the former of thefe circumftances liquid nutriment may 
fometimes be gotten into the ftomach through a flexible cathe- 
ter ; as defcribed in Clafs IJI. 1. 1. 15. In the latter many 
kinds of mild aliment, as milk or broth, have frequently been 
injected «s clyfters, together with a fmall quantity of opium, as 
ten drops of the tincture, three or four times a day ; to which 
alfo might be added very fmall quantities of vinous fpirit. But 
thefe, as far as I have obferved, will not long fuftain a perfon, 
who cannot take any fuftenance by the ftomach. 
2. Another mode of applying nutritive fluids might be by 
extenfive fomentations, or by immerging the whole body in a 
bath of broth, or of warm milk, which might at the fame time 
be coagulated by rennet, or the acid of the calf's ftomach ; broth 
or whey might thus probably be introduced, in part at leaft, into 
the circulation, as a folution of nitre is faid to have been ab- 
forbed in a pediluvium, which was afterwards difeovered by the 
manner in which paper dipped frequently in the urine of the pa- 
tient and dried, burnt and fparkled like touch-paper. Great 
quantity 18 
NUTRIENTIA. 
Art. I. 2. 6. 3, 
quantity of water is alfo known to be abforbed by thofe, who. 
have bathed in the warm bath after exercife and abftinence from 
liquids. Cleopatra was faid.to travel with 4000 milch-affes 
in her train, and to bathe every morning in their milk, 
which flie probably might ufe as a cofmetic rather than a 
nutritive. 
3. The transfufion of blood from another animal into the 
vein of one, who could take no fuftenance by the throat, or di- 
geft none by the ftomach, might long continue to fupport him ; 
and perhaps other nutriment, as milk or mucilage, might be thia 
way introduced into the fyftem, but we have not yet fufficient 
experiments on this fubjeif. See Se£k. XXXII. 4. and Clafs I.. 
2. 3. 25. and Sup. I. 14, 2. 
VII. Various kinds of condiments, or fauces, have been tak- 
en along with vegetable or animal food, and haye been though^ 
by fome to (Lengthen the procefs of digeftion and confequent: 
procefs of nutrition. Of thefe wine, or other fermented liquors, 
vinegar, fait, fpices, and muftard, have been in moft common 
ufe, and I believe to the injury of thoufands. As the ftomach 
by their violent ftimulus at length lofes its natural degree of ir- 
ritability, and indigeftion is the confequence ; which is attend- 
ed vzith flatulency and emaciation. Where any of thefe have 
been taken fo long as to induce a habit, they muft either be 
continued, but not increafed ; or the ufe of them ihould be 
gradually and cautioufly diminiftied or difeontinued, as directed 
in Seft. XII. 7. 8. 
HL Catalogue of the Nutrxentia. 
I. i. Venifon, beef, mutton, hare, goofe, duck, woodcock^ 
fnipe, moor-game. 
2. Oyfters, lob.fters, crabs, (hrimps, muftirooms, eel, 
tench, barbolt, fmelt, turbot, foie, turtle. 
3. Lamb, veal, fucking-pig. 
4. Turkey, partridge, pheafant, fowl, eggs. 
5. Pike, perch, gudgeon, trout, grayling. 
II. Milk, cream, butter, buttermilk, whey, cheefe. 
III. Wheat, barley, oats, peafe, potatoes, turnips, carrots, cab- 
bage, afparagus, artichoke, fpinach, beet, apple, pear, 
plum, apricot, ne&arine, peach, ftrawberry, grape, or- 
ange, melon, cucumber, dried figs,raifins, fugar, honey. 
With a great variety of other roots, feeds, leaves, and 
fruits. 
IV. Water, river-water, fpring-water, calcareous earth. 
V. Air. Art. II. i. i. i. 
INCITANTIA. 
19 
V. Air, oxygene, azote, carbonic acid gas.' 
VI. Nutritive baths and clyfters, transfufion of blood. 
VII. Condiments. 
Art. II. 
INCIT ANTIA. 
I. i. Those things, which increafe the exertions of all 
the irritative motions, are termed incitantia. As alcohol, or 
the fpirituous part of fermented liquors, opium, and many 
drugs, which are ftill eftecmed poifons, their proper dofes not 
being afcertained. To thefe fhould be added the exhilarating 
paflions of the mind, as joy, love : and externally the applica- 
tion of heat, electricity, ether, eflential oils, friCtion, and ex- 
ercife. 
2. Thefe promote both the fecretions and abforptions, in- 
creafe the natural heat, and remove thofe pains, which origin- 
ate from the defect of irritative motions, termed nervous pains ; 
and prevent the convulfions confequent to them. When given 
internally they induce coftivenefs, and deep coloured urine i 
and by a greater dofe intoxication, and its confequenccs. 
II. Observations on the Incitantia, 
I. i. Opium and alcohol increafe all the fecretions and ab~ 
forptions. The increafe of the fecretion of fenforial power ap- 
pears from the violent exertions of drunken people ; the fecre- 
tion of fweat is more certainly excited by opium or wine than 
by any other medicine ; and the increafe of general heat, which 
thefe drugs produce, is an evidence of their effeCt in promoting 
$11 the fecretions; fince an increafe of fecretion is always at- 
tended with increafe of heat in the part, as in hepatic and other 
inflammations. 
2. But as they at the fame time promote abforption ; thofe 
fluids, which are fecreted into receptacles, as the urine, bile, in- 
teftinal and pulmonary mucus, have again their thinner parts 
abforbed; and hence, though the quantity of fecreted fluid 
was increafed, yet as the abforption was alfo increafed, the ex- 
cretion from thefe receptacles is leflened ; at the fame time that 
it is deeper coloured or of thicker confidence, as the urine, al. 
vine 20 
INCITANTIA. 
Art. II. 2. 1.3- 
vine feces, and pulmonary mucus. Whereas the perfpiration 
being fecreted on the furface of the body is vifible in its increaf- 
ed quantity, before it can be reabforbed ; whence arifes that 
erroneous opinion, that opium increafes the cutaneous fecretion, 
and leflens all the others. 
3. It muft however be noted, that after evacuations opium 
feems to promote the abforptions more than the fecretions ; if 
you except that of the fenforial power in the brain, which prob- 
ably fufFers no abforption. Hence its efficacy in reftraining 
haemorrhages, after the veflels are emptied, by promoting vinous 
abforption. 
4. In ulcers the matter is thickened by the exhibition of opi- 
um from the increafed abforption of the thinner parts of it; 
but it is probable, that the whole fecretion, including the part 
which is abfqrbed, is increafed ; and hence qew fibres are fe- 
creted along with the matter, and the ulcer fills with new gran- 
ulations of flelh. But as no ulcer can heal, till it ceafes to dif- 
charge; that is, till the abforption becomes as great as the ex- 
cretion ; thofe medicines, which promote abforption only, are 
more advantageous for the healing an ulcer after it is filled 
with new flefh ; as the Peruvian bark internally, with banda- 
ges and folutions of lead externally. 
5. There are many pains which originate from a want of due 
motion in the part, as thofe occafioned by cold ; and all thofe 
pains which are attended with cold extremities, and are gener- 
ally termed nervous. Thefe are relieved by whatever excites 
the part into its proper actions, and hence by opium and alco- 
hol ; which are the moft univerfal ftimulants we are acquaint- 
ed with. In thefe cafes the effect of opium is produced, as 
foon as the body becomes generally warm ; and a degree of in- 
toxication or deep follows the ceflation of the pain. 
Thefe nervous pains (as they are called) frequently return at 
certain periods of time, and are alfo frequently fucceeded by 
convulfions ; in thefe cafes if opium removes the pain, the con- 
vulfions do not come on. For this purpofe it is belt to exhibit 
it gradually, as a grain every hour, or half hour, till it intoxi- 
cates. Here it muft be noted, that a much lefs quantity will 
prevent the periods of thefe cold pains, than is neceflary to re- 
lieve them after their accefs. As a grain and half of opium 
given an hour before the expected paroxyfm will prevent the 
cold fit of an intermittent fever, but will not foon remove it, 
when it is already formed. For in the former cafe the ufual 
or healthy aflbciations or catenations of motion favour the effect 
of the medicine ; in the latter cafe thefe aflbciations or catena- 
tions Art. II. 2. 1.6. 
INCIT ANTIA. 
21 
lions are difordcred, or interrupted, and new ones are formed, 
which fo far counteract the effeft of the medicine. 
When opium has been required in large dofes to eafe or pre- 
vent convulfions, fome have advifed the patient to omit the ufe 
of wine, as a greater quantity of opium might then be exhibit- 
ed ; and as opium feems to increafe abforption more, and fe- 
cretion lefs, than vinous fpirit; it may in fome cafes be ufeful 
to exchange one for the other ; as in difeafes attended with too 
great evacuation, as diarrhoea, and dyfentery, opium may be 
preferable ; on the contrary in tetanus, or locked-jaw, where 
inflammation of the fyftem might be of fervice, wine may be 
preferable to opium ; fee Clafs III. i. r. 12. I have generally 
obferved, that a mixture of fpirit of wine and warm water, giv- 
en alternately with the dofes of opium, has fooneft and moft 
certainly produced that degree of intoxication, which was necef- 
fary to relieve the patient in the epilepfia dolorifica. 
The external application of opium may alfo be ufed with ad- 
vantage, and efpecially when the ftomach rejefts its internal ufe; 
for this purpofe I have directed the whole fpine of the back to 
be moiftened with tinfture of opium with fuccefs in epileptic 
convulfions. And an extenfive friftion with a liniment confift- 
ing of fix grains of opium, well triturated with an ounce of hog's 
fat, has lately been faid to induce fleep in maniacal cafes, by 
Dr. L. Frank of Florence. 
Injeftions of a folution or tinfture of opium into the reftum 
aft on the general conftitution, but require about double the 
quantity for that purpofe as when taken into the ftomach. In- 
jeftions of a folution of opium into the urethra may be of fervice 
to relieve pain, or to produce the abforption of the new veffels 
produced by inflammation, after fufficient evacuations, as is feen 
when it is applied to an inflamed eye. Or laftly, to alleviate 
the pain from acrid difeharges by increafing their abforption, or 
the pain from torpor of the part, as in fome tooth-achs, by its 
external application. 
6. There is likewife fome relief given by opium to inflamma- 
tory pains, or thofe from excefs of motion in the affefted part; 
but with this difference, that this relief from the pains, and the 
fleep, which it occafions, do not occur till fome hours after the 
exhibition of the opium. This requires to be explained ; after 
the ftimulus of opium or of alcohol ceafes, as after common 
drunkennefs, a confequent torpor comes on; and the whole 
habit becomes lefs irritable by the natural ftimuli. Hence the 
head-achs, ficknefs, and languor, on the next day after intoxica- 
tion, with cold ikin, and general debility. Now in pains from 
excefs of motion, called inflammatory pains, when opium is giv- 
/ cn» 22 
INCITANTIA. 
Art. IL 2. 1. 7 
en, the pain is not relieved, till the debility comes on after the 
ftimulus ceafes to ait; for then after the greater ftimulus of the 
opium has exhaufted much of the fenforial power, the lefs ftim- 
ulus, which before caufed the pain, does not now excite the part 
into unnatural action. 
In thefe cafes the ftimulus of the opium firft increafes the pain; 
and it fometimes happens, that fo great a torpor follows, as to 
produce the death or mortification of the affeited part; whence 
the danger of giving opium in inflammatory difeafes, efpecially 
in inflammation of the bowels; but in general the pain returns 
with its former violence, when the torpor above mentioned 
ceafes. Hence thefe pains attended with inflammation are beft 
relieved by copious Venefection, other evacuations, and the clafs 
of medicines called torpentia. 
7. Thefe pains from excefs of motion are attended with in- 
creafed heat of the whole, or of the affeited part, and a ftrong 
quick pulfe ; the pains from defett of motion are attended with 
cold extremities, and a weak pulfe ; which is alfc generally more 
frequent than natural, but not always fo. 
8. Opium and alcohol are the only two drugs, we are much 
acquainted with, which intoxicate; and by this circumftance 
are eafily diftinguilhed from the fecernentia and forbentia* 
Camphor, and cicuta, and nicotiana, are thought to induce a 
kind of intoxication ; and there are many other drugs of this 
clafs, whofe effeils are lefs known, or their dofes not afeertain- 
ed; as atropa belladonna, hyofeyamus, ftramonium, prunus 
laurocerafus, menifpermum, cynoglofliim, fome fungi, and the 
water diftilled from black cherry-ftones ; the laft of which was 
once much in ufe for the convulfions of children, and was faid 
to have good effeit; but is now improvidently left out of our 
pharmacopoeias. I have known one leaf of the laurocerafus, 
ihred and made into tea, given every morning for a week with 
no ill confequence to a weak hyfteric lady, but rather perhaps 
With advantage. 
It is probable, that other bitter kernels, as thofe of horfe-chef- 
nuts, and of acorns, xfculus hippocaftanum, and quercus robur, 
may poflefs fomewhat of an intoxicating quality ; and by thig 
kind of ftimulus, as well as by their bitter part, may be ufed to 
prevent the paroxyfm of an ague, if adminiftered an hour be- 
fore the expected accefs of it, as is lately affirmed by Dr. Fuchs 
of Jena ; who fays, an extract prepared from the ripe kernels of 
the horfe-chefnut aits like an extrait of Peruvian bark ; and 
adds that the bark alfo of this tree is ufed with fuccefs initead 
of the Peruvian bark. 
9. The pernicious effects of a continued ufe of much vinous 
fpirir. Art. II. 2. 1. 10. 
INCIT ANTIA. 
23 
fpirit is daily feen and lamented by phyficians; iiot only early 
debility, like premature age, but a dreadful catalogue of difeafe* 
is induced by this kind of intemperance ; as dropfy, gout, lep- 
rofy, epiiepfy, infanity, as defcribed in Botanic Garden, Part IL 
Canto III. line 357. The ftronger or lefs diluted the fpirit is 
taken, the fooner it feems to deftroy, as in dram-drinkers ; but 
ft ill fooner, when kernels of apricots, or bitter almonds, or lau- 
rel-leaf, are infufed in the fpirit, which is termed ratafia ; as 
then two poifons are fwallowed at the fame time. And vine- 
gar, as it contains much vinous fpirit, is probably a noxious part 
of our diet. And the diftilled vinegar, which is commonly fold 
in the (hops, is truly poifonous, as it is generally diftilled by 
means of a pewter or leaden alembic-head or worm-tube, and 
abounds with lead ; which any one may detedl by mixing with 
it a folution of liver of fulphur. Opium, when taken as a lux- 
ury, not as a medicine, is as pernicious as alcohol; as Baron 
de Tott relates in his account of the opium-eaters in Turkey. 
10. It muft be obferved, that a frequent repetition of the ufe 
of this clafs of medicines fo habituates the body to their ftimu- 
lus, that their dofe may gradually be increafed to an aftonifliing 
quantity, fuch as otherwife would inftantly deftroy life ; as is 
frequently feen in thofe, who accuftom themfelves to the daily 
ufe of alcohol and opium ; and it would feem, that thefe unfor- 
tunate people become difeafed as foon as they omit their ufual 
potations ; and that the consequent gout, dropfy, palfy, or pim- 
pled face, occur from the debility occafioned from the want of 
accuftomed ftimulus, or to fome change in the contractile fi- 
bres, which requires the continuance or increafe of it. Whence 
the cautions necelfary to be obferved are mentioned in Sect. 
XII. 7. 8. 
11. It is probable, that fome of the articles in the fubfequent 
catalogue do not induce intoxication, though they have been 
efteemed to do fo ; as^ tobacco, hemlock, nux vomica, ftavifa- 
gria ; and on this account Ihould rather belong to other arrange- 
ments, as to the fecernentia, or forbentia, or invertentia. 
IL 1. Externally the application of heat, as the warm bath, 
by its ftimulus on the ikin excites the excretory dudls of the 
perfpirativc glands, and the mouths of the lymphatics, which open 
on its furface, into greater action ; and in confequence many 
other irritative motions, which are aflbeiated with them. To 
this increafed aClion is added pleafurable fenfation, which adds 
further activity to the fyftem ; and thus many kinds of pain re- 
ceive relief from this additional atmofphere of heat. 
The ufe of a warm bath of about 96 or 98 degrees of heat, 
for half an hour once a day for three or four months, I have 
Vol. I. Ppp known 24 
1NC1TANT1A. 
Art. II. 2. 2. 
known o£ great fervice to weak people, and is perhaps the leaft 
noxious of all unnatural ftimuli ; which however, like all other 
great excitement, may be carried to excefs, as complained of by 
the ancients. The unmeaning application of the words relaxation 
and bracing to warm and cold baths has much prevented the 
ufe of this grateful ftimulus ; and the mifufe of the term warm- 
bath, when applied to baths colder than the body, as to thofe of 
Buxton and Matlock, and to artificial baths of lefs than 90 de- 
grees of heat, which ought to be termed cold ones, has contrib- 
uted to miilead the unwary in their application. 
The ftimulus of wine, or fpice, or fait, increafes the heat of 
the fyftem by increafing all or fome of the fecretions ; and hence 
the ftrength is diminilhed afterwards by the lofs of fluids, as 
well as by the increafed aClion of the fibres.' But the ftimulus 
of the warm-bath fupplies heat rather than produces it; and 
rather fills the fyftem by increafed abforption, than empties it 
by increafed fecretion ; and may hence be employed with advan- 
tage in almoft all cafes of debility with cold extremities, perhaps 
even in anafarca, and at the approach of death in fevers. In 
thefe cafes a bath much beneath 98 degrees, as of 80 or 85, 
might do injury, as being a cold-bath compared with the heat 
of the body, though fuch a bath is generally called a warm one. 
The activity of the fyftem thus produced by a bath of 98 de- 
grees of heat, or upwards, does not feem to render the patients 
liable to take cold, when they come out of it; for the fyftem is 
lefs inclined to become torpid than before, as the warmth thus 
acquired by communication, rather than by increafed action, 
continues long without any confequent chillnefs. Which ac- 
cords with rhe obfervation of Dr. Fordyce, mentioned in Sup. 
I. 5. 1. who fays, that thofe who are confined fome time in an 
atmofphere of 120 or 130 degrees of heat, do not feel cold or 
look pale on coming into a temperature of 30 or 40 degrees; 
which would produce great palenefs and fenfation of coldnefs 
in thofe, who had been fome time confined in an atmofphere of 
only 86 or 90 degrees of heat. Treatife on Simple Fever, p. 
168. 
Hence heat, where it can be confined on a torpid part along 
with moifture, as on a fcrofulous tumour, will contribute to 
produce fuppuration or refolution. This is done by applying a 
warm poultice, which fnould be frequently repeated ; or a plat- 
ter of refin, wax, or fat ; or by covering the part with oiled 
filk ; both which laft prevent the pcrfpirable matter from efcap- 
ing as well as the heat of the part, as thefe fubftances repel 
moifture, and are bad conductors of heat. Another great ufe 
*f the ftimulus of heat is by applying it to torpid ulcers, which 
are Art. II. 2. 2. 1. 
INCITANTIA. 
25 
arc generally termed fcrofulous or fcorbutic, and are much eaGer 
inclined to heal, when covered with feveral folds of flannel. 
Mr. had for many months been afflicted with an ulcer 
in perinteo, which communicated with the urethra, through 
which a part of his urine was daily evacuated with confiderable 
pain ; and was reduced to a great degree of debility. He ufed 
a hot-bath of 96 or 98 degrees of heat every day for half an 
hour during about fix months. By this agreeable ftimulus re- 
peated thus at uniform times not only the ulcer healed, contra- 
ry to the expectation of his friends, but he acquired greater 
health and Itrength, than he had for fome years previouily ex- 
perienced. 
Mrs. was affected with tranfient pains, which were call- 
ed nervous fpafms, and with great fear of difeafes which ilie 
did not labour under, with cold extremities, and general debil- 
ity. She ufed a hot-bath every other day of 96 degrees of heat 
for about four months, and recovered a good ftate of health, 
with greater ftrength and courage, than (he had poffeffed for 
many months before. 
Mr. Z. a gentleman about 65 years of age, had lived rather 
intemperately in refpe<Sf to vinous potation, and had for many 
years had annual vifits of the gout, which now became irregu- 
lar, and he appeared to be lofing his ftrength, and beginning to 
feel the effects of age. He ufed a bath, as hot as was agreea- 
ble to his fenfations, twice a week for about a year and half, 
and greatly recovered his health and ftrength with lefs frequent 
and lefs violent returns of regular gout, and is now near 80 years 
of age. 
When Dr. Franklin, the American philofopher, was in En- 
gland many years ago, I recommended to him the ufe of a 
warm-bath twice a week to prevent the too fpeedy accefs of old 
age, which he then thought that he felt the approach of, and 1 
have been informed, that he continued the ufe of it till near his 
death, which was at an advanced age. 
All thefe patients were advifed not to keep themfelves warm- 
er than their ufual habits, after they came out of the bath, wheth- 
er they went into bed or not; as the defign was not to promote 
perfpiration, which weakens all conftitutions, and fcldom is of 
fervice to any. Thus a flannel fliirt, particularly if it be worn 
in warm weather, occafions weaknefs by ftimulating the Ikin by 
its points into too great action, and producing heat in confe- 
quence; and occafions emaciation by increafing the difeharge 
of pcrfpirable matter; and in both thefe refpeCts differs from 
the effect of warm bathing, which communicates heat to the 
fyftem 26 
imr Antia. 
Art. II. 2. 2. 2. 
fyftem at the fame time that it ftimulates it, and caufes abforp- 
tion moie than exhalation. 
Thofe who have remained half an hour in a warm bath, when 
they have previoufly been exhaufted by exercife, or abftinence 
from food or fluids, have abforbed fo much as to increafe their 
weight confiderably. Dr. Jurin found an increafe of weight to 
18 ounces by flecping in a cool room after a day's exercife and 
abftinence, fo much in that fituation was abforbed from the at- 
mofphere. But it has lately been obferved by Dr. Rollo and by 
Dr. Currie, that feme patients did not weigh heavier after com- 
ing out of the warm bath, and being wiped dry. From whence 
we may conclude, that thefe patients were not previoufly in a 
Rate of inannition ; or that they had remained fo long in the 
bath as to lofe fomewhat by the perpetual wafte of the fyftem 
by digeftion, circulation, and fecretion. And certainly as no 
wafte occurs by the ufe of the warm bath, this muft he the moft 
harmlefs, consequently the moft falutary of all increafed ftimuli. 
See Clafs I. i. 2. 3. 
2. The effect of the paflage of an eleCtric fhock through a 
paralytic limb in caufing it to contrail, befides the late experi- 
ments of Galvani and Volta on frogs, entitle it to be clafled 
amongft univerfal ftimulants. Ele&ric fhocks frequently re- 
peated daily for a week or two remove chronical pains, as the 
pleurodyrie chronica, Clafs I. 2. 4. 14. and other chronic pains, 
which are termed rheumatic, probably by promoting the abforp- 
tion of fome extravafated material. Scrofulous tumours are 
fometimes abforbed, and fometimes brought to fuppurate by 
palling eleCtric fhocks through them daily for two or three weeks. 
Mifs , a young lady about eight years of age, had a 
{welling about the Ilze of a pigeon's egg on her neck a little 
below her ear, which long continued in an indolent ftate. 
Thirty or forty fmall eledtric fhocks were palled through it once 
or twice a day for two or three weeks, and it then fuppurated and 
healed without difficulty. For this operation the coated jar of 
{he eleHric machine had on its top an electrometer, which 
meafured the fhocks by the approach of a brafs knob, which 
communicated with the external coating to another, which 
communicated with the internal one, and their diftance was ad- 
jufted by a fcrew. So that the fhocks were fo fmall as not to 
alarm the child, and the accumulated electricity was frequently 
difeharged as the wheel continued turning. The tumour was 
enclofcd between two other brafs knobs, which were fixed on 
wires, which palled through glafs tubes ; the tubes were cement- 
ed in two grooves on a board, fo that at one end they were 
nearer Art. II. 2. 3. 1. 
INCITANTIA. 
27 
nearer each other than at the other, and the knobs were pufhed 
out fo far as exactly to include the tumour. 
Inflammations of the eyes without fever are frequently cured 
by taking a ilream of very fmall ele&ric fparks from them, or 
giving the eleCtric fparks to them, once or twice a day for a 
week or two ; that is, the new veflels, which conflitute inflam- 
mation in thefe inirritable conflitutions, are abforbed by the ac- 
tivity of the abforbents induced by the ftimulus of the electric 
aura. For this operation the eafieft method is to fix a pointed 
wire to a flick of fealing wax, or to an infulating handle of glafs; 
one end of this wire communicates with the prime conductor, 
and the; point is approached near the inflamed eye in every di- 
rection/ 
III. Externally the application of ether, and of eflential oils, 
as of cloves or cinnamon, feems to poflefs a general flimulating 
effect. As they inftantly relieve tooth-ach, and hiccough, 
when thefe pains are not in violent degree •, and camphor in 
large dofes is faid to produce intoxication ; this effect however 
I have not been witnefs to, and have reafon to doubt. 
Ether dropped into the ears of fome deafifh people, feems to 
poflefs a two-fold effect, one of diflblving the indurated ear-wax, 
and the other of flimulating the torpid organ, but it is liable to 
give fome degree of pain, unlefs it be freed from the fulphurous 
acid, fome of which arifes along with it in diflillation ; to pu- 
rify it from this material it fhould be rectified from manganefe. 
See Clafs I. 2. 5. 6. Lime added to impure ether may alfo 
unite with the fulphuric acid, if fuch exilts in it, and form fele- 
nite, and fubfide. 
The manner in which ether and the eflential oil operate on 
the fyftem when applied externally, is a curious quellion, as 
pain is lo immediately relieved by them, that they mufl feem to 
penetrate by the great fluidity or expanfive property of a part of 
them, as of their odoriferous exhalation or vapour, and thus ftim- 
ulate the torpid part, and not by their being taken up by the ab- 
forbent veflels, and carried thither by the long courfe of circula- 
tion ; nor is it probable, that thefe pains are relieved by the 
fympathy of the torpid membrane with the external fkin, which 
is thus ftimulated into action ; as it does not fucceed, unlefs it 
is applied over the pained part. Thus there appears to be three 
different modes by which extraneous bodies may be introduced 
into the fyllem, befides that of abforption. ill. By ethereal 
tranfition, as heat and electricity ; 2d. by chemical attraction, 
as oxygen ; and 3d. by expanfive vapour, as ether and eflen- 
tial oils. 
IV. The perpetual neceflity of the mixture of oxygen gas 
with 28 
INCIT ANTIA. 
Art. II. 2. 4. 1, 
with the blood in the lungs evinces, that it mull aft as a ftimu- 
lus to the fanguiferous fyftem, as the motions of the heart and 
arteries prefently ceafe, when animals are immerfed in airs 
which poffels no oxygen. It may alfo fubfequently anfwer 
another important purpofe, as it is probable that it affords the 
material for the produftion of the fenforial power ; which is 
fuppofed to be fecreted in the brain or medullary part of the 
nerves ; and that the perpetual demand of this fluid in refpira- 
tion is occafioned by the fenforial power, which is fuppofed to 
be produced from it, being too fubtle to be long confined in any 
part of the fyftem. 
Another proof of the ftimulant quality of oxygen appears 
from the increafed acrimony, which the matter of a common 
abfcefs pofl'efles, after it has been expofed to the air of the at- 
mofphere, but not before ; and probably all other contagious 
matters owe their fever-producing property to having been con- 
verted ihto acids by their union with oxygen. See Clafs II. i. 8. 
As oxygen penetrates the fine moift membranes of the air-vef- 
fels of the lungs, and unites with the blood by a chemical at- 
traftion, as is feen to happen, when blood is drawn into a baton, 
the lower furface of the craffamentum is of a very dark red to 
long as it is covered from the air by the upper furface, but be- 
comes florid in a fhort time on its being expofed to the atmof- 
phere ; the manner of its introduftion into the fyftem is not 
probably by animal abforption but by chemical attraction, in 
which circumftance it differs from the fluids before mentioned 
both of heat and eleftricity, and of ether and eflential oils. 
As oxygen has the property of palling through moift animal 
membranes, as firft difeovered by the great Dr. Prieftley, it is 
probable it might be of ufe in vibices, and petechiae in fevers, 
and in other bruifes ; if the Ikin over thofe parts was kept moift 
by warm water, and covered with oxygen gas by means of an 
inverted glafs, or even by expofing the parts thus moiftened to 
the atmofphere, as the dark coloured extravafated blood might 
thus become florid, and by its increafe of ftimulus facilitate its 
reabforption. 
Two weak patients, to whom I gave oxygen gas in as pure a 
ftate as it can eafdy be produced from Exeter manganefe, and 
in the quantity of about four gallons a day, feemed to feel re- 
frelhed, and ftronger, and to look better immediately after ref- 
piring it, and gained ftrength in a Ihort time. Two others, 
one of whom laboured under confirmed hydrothorax, and the 
other under a permanent and uniform difficulty of refpiration, 
were not refrelhed, or in any way ferved by the ufe of oxygen in 
the above quantity of four gallons a day for a fortnight, which Art. II. 2. 5. 1. 
INCITANTIA. 
29 
I afcribed to the inirritability of the difeafed lungs. For other 
cafes the reader is referred to the publications of Dr. Beddoes ; 
Confiderations on the Ufe of Factitious Airs, fold by Johnfon, 
London. 
Its effeCls would probably have been greater in refpedt to the 
quantity breathed, if it had been given in a dilute (late, mixed 
with io or 20 times its quantity of atmofpheric air, as otherwife 
much of it returns by expiration without being deprived of its 
quality, as may be feen by the perfon breathing on the flame of a 
candle, which it enlarges. See the Treatife of Dr. Beddoes 
above mentioned. 
Mr. Scott in his letters in the Bombay Courier gave the black 
calciform ore of manganefe in the quantity, he fays, of feveral 
drachms a day without any inconvenience to a venereal patient, 
hoping to ferve him by the oxygen contained in that calx. I 
have formerly given lapis calaminaris to the quantity of 20 
grains twice a day in confumption, without inconvenience, and I 
fuppofe this calciform ore of zinc, as well as the ruft of iron, 
may be an union of thofe metals with oxygen, and may probably 
be given internally with more fafety than calces of lead, which 
were once famous in confumptions. See Clafs II. 1. 5. 2. and 
Article IV. 2. 7. 1. 
V. Thofc paffions, which are attended with pleafurable fenfa- 
tion, excite the fyftem into increafed aCHon in confequence of that 
fenfation, as joy, and love, as is feen by the flufh of the fkin. 
Thofe pallions, which are attended with difagreeable fenfation, 
produce torpor in general by the expenfe of fenforial power oc- 
cafioned by inactive pain ; unlefs volition be excited in confe- 
quence of the painful fenfation ; and in that cafe an increafed 
activity of the fyftem occurs ; thus palenefs and coldnefs are the 
confequence of fear,but warmth and rednefs are the confequence 
of anger. 
VI. Befides the exertions of the fyftem occafioned by increaf- 
ed flimuli, and confequent irritation, and by the paffions of the 
mind above defcribed, the increafed actions occafioned by exer- 
cife belong to this article. Thefe may be divided into the ac- 
tions of the body in confequence of volition, which is generally 
termed labour ; or fecondly, in confequence of agreeable fenfa- 
tion, which is termed play or fport; thirdly, the exercife occa- 
fioned by agitation, as in a carriage or on horfeback ; fourthly, 
that of fridlion, as with a brufh or hand, fo much ufed in the 
baths of Turkey ; and laftly, the exercife pi twinging. 
The firtt of thefe modes of exercife is frequently carried to 
great excefs even amongft our own labourers, and more fo un- 
der the lafh of flavery ; fo that the body becomes emaciated and 
finks 30 
INCITANTIA. 
Art. II. a. 6. t. 
finks under either the prefent hardlhips, or by a premature old 
age. The fecond mode of exercife is feen in the play of all 
young animals, as kittens, and puppies, and children ; and is fo 
necefiary to their health as well as to their pleafure, that thofe 
children, which are too much confined from it, not only become 
pale-faced and bloated, with tumid bellies, and confequent 
worms, but are liable to get habits of unnatural actions, as 
twitching of their limbs, or fome parts of their countenance ; 
together with an ill-humoured or difeontented mind. 
Agitation in a carriage or on horfeback, as it requires fome 
little voluntary exertion to preferve the body perpendicular, but 
much lefs voluntary exertion than in walking, feems the beft 
adapted to invalids; who by thefe means obtain exercife prin- 
cipally by the ftrength of the horfe, and do not therefore too 
much exhauft their own fenforial power., The ufe of fritSlion 
with a brulh or hand, for half an hour or longer morning and 
evening, is (till better adapted to thofe, who are reduced to ex- 
treme debility; and none of their own fenforial power is thus 
expended, and affords fomewhat like the warm-bath activity 
without feif-exertion, and is ufed as a luxury after warm bathing 
in many parts of Afia. 
Another kind of exercife is that of fwinging, which requires 
fome exertion to keep the body perpendicular, or pointing to- 
wards the centre of the fwing, but is at the fame time attended 
with a degree of vertigo ; and is deforibed in Clafs II. i. 6. 7. 
IV. 2. 1. 10. Sup. I. 3. and 15. 
The neceffityof much exercife has perhaps been more infilled 
upon by phyficians, than nature feems to demand. Few ani- 
mals exercife themfelves fo as to induce vifible fweat, unlefs urg- 
ed to it by mankind, or by fear, or hunger. And numbers of 
people in our market towns, 'of ladies particularly, with fmall 
fortunes, live to old age in health, without any kind of exercife 
of body, or much activity of mind. 
In fummer weak people cannot continue too long in'the air, if 
it can be done without fatigue ; and in winter they fhould go 
out feveral times in a day for a few minutes, ufing the cold air 
like a cold-bath, to invigorate and render them more hardy. 
III. Catalogue of the Incitantia. 
I. Papaver fomniferum ; poppy, opium. 
Alcohol, wine, bser, cyder. 
Prunus lauro-cerafus ; laurel,diftilledwaterfiom the leaves. 
Prunus cerafus; black cherry, dillilled water from the 
kernels. 
Nicotiana Art. lil. 1.1. 
SECERNENTIA. 
31 
Nicotiana tabacunl j tobacco ; the eflential oil, decod ion 
of the leaf. 
Atropa belladonna ; deadly nightlhade, the berries. 
Datura ftramoneum ; thorn-apple, the fruit boiled in milki 
Hyofcyamus reticulatus; henbane, the feeds and leaves. 
Cynogloflum; hounds tongue. 
Menifpermum, cocculus; Indian berry. 
Amygdalus amarus; bitter almond. 
Cicuta ; hemlock. Conium maculatum ? 
Strychnos nux vomica ? 
Delphinium ftavifagria ? 
II. Externally, heat, eleftricity. 
III. Ether, eflential oils. 
IV. Oxygen gas. 
V. Paflions of love, joy, anger. 
VI. Labour, play, agitation, friftion. 
Art. III. 
SECERNENTIA* 
I. Those things which increafe the irritative motions, which 
conftitute fecretion, are termed fecernentia; which are as vari- 
ous as the glands, which they ftimulate into aftion. 
i. Diaphoretics, as aromatic vegetables, eflential oils, ether, 
volatile alkali, neutral faits, antimonial preparations, external 
heat, exercife, friftion, cold water for a time with fubfequent 
warmth, blifters, eleftric fluid. 
2. Sialagogues, as mercury internally, and pyrethrum exter- 
nally. 
3.' Expeftorants, as fquill, onions, gum ammoniac, feneka 
root, mucilage : fome of thefe increafe the pulmonary perfpira- 
tion, and perhaps the pulmonary mucus. 
4. Diuretics, as neutral faits, fixed alkali, balfams, refins, af- 
paragus, cantharides. 
5. Cathartics of the mild kind, as fenna, jalap, neutral faits, 
manna. They increafe the fecretions of bile, pancreatic juice, 
and inteftinal mucus. 
6. The mucus of the bladder is increafed by cantharides, and 
perhaps by oil of turpentine. 
Vol. I 7* The 32 
SECERNENTIA. 
Art. III. 1.1. 7. 
7. The mucus of the return by aloe internally, by clyfters 
and fuppofitories externally. 
8. The mucus of the cellular membrane is increafed by blif- 
ters and finapifms. 
9. The mucus of the noftrils is increafed by errhines of the 
milder kind, as marum, common fnuff. 
10. The fecretion of tears is increafed by volatile faits, the 
Vapour of onions, by grief, and joy. 
11. All thofe medicines increafe the heat of the body, and 
remove thofe pains, which originate from a defeat of motion in 
the veflels, which perform fecretion; as pepper produces a glow 
on the Ikin, and balfam of Peru is faid to relieve the flatulent 
colic. But thefe medicines differ from the preceding clafs, as 
they neither induce coftivenefs nor deep coloured urine in their 
ufual dofe, nor intoxication in any dofe. 
12. Yet if any of thefe are ufed unneceffarily, it is obvious, 
like the incitantia, that they muft contribute to fhorten our lives 
by fooner rendering peculiar parts of the fyftem difobedient to 
their natural flimuli. Of thofe in daily ufe the great excefs of 
common fait is probably the moft pernicious, as it enters all our 
cookery, and is probably one caufe of fcrofula, and of fea-fcur- 
vy, when joined with other caufes of debility. See Botanic 
Garden, Part II. Canto IV. line 221. Spices taken to excefs 
by {Emulating the ftomach, and the veflels of the Ikin by affoci- 
ation, into unneceffary aftion, contribute to weaken thefe parts 
of the fyftem, but are probably lefs noxious than the general ufe 
of fo much fait. 
II. Observations on the Secernentia. 
I. 1. Some of the medicines of this clafs produce abforption 
in fome degree, though their principal effect is exerted on the 
fecerning part of our fyftem. We {hall have occafion to ob- 
ferve a fimilar ciicumftance in the next clafs of medicines term- 
ed Sorbentia ; as of thefe fome exert their effects in a fmaller 
degree on the fecerning fyftem. Nor will this furprife any one, 
who has obferved, that all natural objects are prefented to us 
in a ftate of combination ; and that hence the materials, which 
produce thefe different effects, are frequently found mingled in 
the fame vegetable. Thus the pure aromatics increafe the ac- 
tion of the veflels, which fecrete the perfpirable matter ; and 
the pure aftringents increafe the action of the veflels, which ab- 
forb the mucus from the lungs, and other cavities of the body ; 
hence it muft happen, that nutmeg, which poffeffes both thefe 
qualities, fhould have the double effect above mentioned. 
Other Art. III. 2. 1.2. 
SECERNENTIA. 
33 
Other drugs have this double effect, and belong either to the 
clafs of Secernentia or Sorbentia, according to the dofe in which 
they are exhibited. Thus a fmall dofe of alum increafes ab- 
forption, and induces coltivenefs ; and a large one increafes the 
fecretions into the inteftinal canal, and becomes cathartic. And 
this accounts for the conftipation of the belly left after the pur- 
gative quality of rhubarb ceafes, for it increafes abforption in 
a fmaller dole, and fecretion in a greater. Hence when a part 
of the larger dofe is carried out of the habit by (tools, the fmall 
quantity which remains induces coltivenefs. Hence rhubarb 
exhibited in fmall dofes, as two or three grains twice a day, 
ftrengthens the fyftem by increafing the action of the abtbrbcnt 
veflels, and of the inteftinal canal. 
2. Diaphoretics. The perfpiration is a fecretion from the 
blood in its paflage through the capillary veflels, as other fecre- 
tions are produced in the termination of .the arteries in the va- 
rious glands. After this fecretion the blood lofes its florid 
colour, which it regains in its paflage through the lungs ; which 
evinces that fomething befides water is fecreted on the ikins of 
animals. 
No ftatical experiments can afcertain the quantity of our per- 
fpiration ; as a continued abforption of the moifture of the at- 
mofphere exilts at the fame time both by the cutaneous and pul- 
monary lymphatic. 
3. Every gland is capable of being excited into greater exer- 
tions by an appropriated ftimulus applied either by its mixture 
with the blood immediately to the fecerning veflel, or applied 
externally to its excretory dudl. Thus mercury internally pro- 
motes an increafed falivation, and pyrethrum externally applied 
to the excretory dudls of the falival glands. Aloes himulate 
the redtum internally mixed with the circulating blood ; and 
fea-falt by injedtion externally. Now as the capillaries, which 
fecrete the perfpirable matter, lie near the furface of the body, 
the application of external heat adts immediately on their excre- 
tory dudls, and promotes perfpiration ; internally thofe drugs 
which poflefs a fragrant eflential oil, or fpiritus redtor, produce 
this effect, as the aromatic vegetables, of which the number is 
very great. 
4. It mull be remembered, that a due quantity of fome 
aqueous vehicle muft be given to fupport this evacuation ; oth- 
erwife a burning heat without much vifible fwcat mult be the 
confequence. When the (kin acquires a degree of heat much 
above 108, as appears by Dr. Alexander's experiments, no vifi- 
ble fwcat is produced ; which is owing to the great heat of the 
(kin evaporating it as hallily, as it is fecreted ; and, where the 
fweat 34 
SECERNENTIA. 
Art. HI. 2. r. 5.' 
fweat is fecreted in abundance, its evaporation cannot carry off 
the exuberant heat, like the vapour of boiling water; becaufe a 
great part of it is wiped off, or abforbed by the bed-clothes; or 
the air about the patient is not changed fufliciently often, as it 
becomes faturated with the perfpirable matter. And hence it 
is probable, that the wafte of perfpirable matter is as great, or 
greater, when the Ikin is hot and dry, as when it ftands in 
drops on the Ikin; as appears from the inextinguiihable 
thirft. 
Hence Dr. Alexander found, that when the heat of the body 
was greater than 108, nothing produced fweats but repeated 
draughts of cold water ; and of warm fluids, when the heat 
was much below that degree. And that cold water which pror 
cured fweats inftantaneoufly when the heat was above 108, 
flopped them as certainly when it was below that heat; and 
that flannels, wrung out of warm water and wrapped round the 
legs and thighs, were then moll certainly produ&ive of fweats. 
5. The diaphoretics are all faid to fucceed much better, if given 
early in the morning, about an hour before fun-rife, than at any 
other time; which is owing to the great excitability of every 
part of the fyftem after the fenforial power has been accumu- 
lated during fleep. In thofe, who have heCtic fever, or the fe- 
bricula, or noClurnal fever of debility, the morning fweats are 
owing to the decline of the fever-fit, as explained in SeCt. XXXIL 
9. In fome of thefe patients the fweat does not occur till they 
awake ; becaufe then the fyftem is ftill more excitable than du- 
ring fleep, becaufe the afliftance of the voluntary power in 
refpiration facilitates the general circulation, See Clafs L 
2. 1. 3. 
6. It muft be obferved, that the ikin is very dry and hard to 
the touch, where the abforbents, which open on its furface, do 
not aCt; as in fome dropfies, and other difeafes attended with 
great thirft. This drynefs, and ihrivelled appearance, and rough- 
nefs, are owing to the mouths of the abforbents being empty of 
their accuftomcd fluid, and is diftinguiihable from the drynefs 
of the ikin above mentioned in the hot fits of fever, by its not 
being attended with heat. 
As the heat of the ikin in the ufual temperature of the air 
always evinces an increafed perfpiration, whether vifible or not, 
the heat being produced along with the increafe of fecretion ; 
it follows, that a defect of perfpiration can only exift, when the 
ikin is cold. 
7. Volatile alkali is a very povzerful diaphoretic, and partic- 
ularly if exhibited in wine-whey ; twenty drops of fpirit of 
hartihorn every half hour in half a pint of wine-whey, if the pa- 
tient Art. III. 2. i. 8. 
SECERNENTIA. 
35 
tient be kept in a moderately warm bed, will in a few hours 
elicit moft profufe fweats. 
Neutral faits promote invifible perfpiration, when the fkin is 
not warmed much externally, as is evinced from the great thirft, 
which fucceeds a meal of fait provifions, as of red herrings. 
When thefe are fufiiciently diluted with water, and the ficin 
kept warm, copious fweats without inflaming the habit, are the 
confequence. Half an ounce of vinegar faturated with volatile 
alkali, taken every hour or two hours, well anfwers this pur- 
pofe ; and is preferable perhaps in general to all others, where 
fweating is advantageous. Boerhaave mentions one cured of 
a fever by eating red-herrings or anchovies, which, with repeat- 
ed draughts of warm water or tea, would I fuppofe produce co- 
pious perfpiration. 
Antimonial preparations have alfo been of late much ufed 
with great advantage as diaphoretics. For the hiftory and ufe 
of thefe preparations I fliall refer the reader to the late writers 
on the Materia Medica, only obferving that the ftomach be- 
comes fo foon habituated to its ftimulus, that the fecond dofe 
may be confiderably increafed, if the firft had no operation. 
Where it is advifable to procure copious fweats, the emetics, 
as ipecacuanha, joined with opiates, as in Dover's powder, pro- 
duce this effect with greater certainty than the above. 
8. We muft not difmifs this fubjecSf without obferving, that 
perfpiration is defigned to keep the ficin flexible, as the tears are 
intended to clean and lubricate the eye ; and that neither of 
thefe fluids can be confidered as excretions in their natural Rate, 
but as fecretions. See Clafs I. i. 2. 3. And that therefore 
the principal ufe of diaphoretic medicines is to warm the fkin, 
and thence in confequence to produce the natural degree of in- 
fenfible perfpiration in languid habits. 
9. When the fkin of the extremities is cold, which is always 
a fign of prefent debility, the digeition becomes frequently im- 
paired by aflociation, and cardialgia or heartburn is induced 
from the vinous or acetous fermentation of the aliment. In this 
difeafe diaphoretics, which have been called cordials, by their 
aftion on the ftomach reitore its exertion, and that of the cu- 
taneous capillaries by their aflociation with it, and the fkin be- 
comes warm, and the digeflion more vigorous. 
10. But a blifter afts with more permanent and certain ef- 
fe<£t by ftimulating a part of the fkin, and thence affecting the 
whole of it, and of the ftomach by aflociation, and thence re- 
moves the moft obftinate heartburns and vomitings. From 
this the principal ufe of blitters is underftood, which is to in- 
vigorate the exertions of the arterial and lymphatic veflels of the 
fkin^ 36 
SECERNENTIA. 
Art. III. 2. 2. 1. 
(kin, producing an increafe of infenfible perfpiration, and of cu- 
taneous abforption ; and to increafe the action of the ftomach, 
and the confequent power of digeftion ; and thence by fympa- 
thy to excite all the other irritative motions : hence they relieve 
pains of the cold kind, which originate from defeCt of motion; 
not from their introducing a greater pain, as fome have imagin- 
ed, but by ftimulating the torpid veffels into their ufual aCtion ; 
and thence increafing the aCtion and confequent warmth of the 
whole fkin, and of all the parts which are affociated with it. 
II. i. Sialagogues. The preparations of mercury confift of 
a folution or corrofion of that metal by fome acid ; and, when 
the dofe is known, it is probable that they are all equally effica- 
cious. As their principal ufe is in the cure of the venereal dif- 
eafe, they will be mentioned in the catalogue amongft the for- 
bentia. Where falivation is intended, it is much forwarded by 
a warm room and warm clothes ; and prevented by expofing 
the patient to his ufual habits of cool air and drefs, as the mer- 
cury is then more liable to go off by the bowels. 
2. Any acrid drug, as pyrethrum, held in the mouth aCts as 
a fialagogue externally by ftimulating the excretory duds of the 
falivary glands; and the filiqua hirfuta applied externally to the 
parotid gland, and even hard fubftances in the ear, are faid to 
have the fame effect. Maftich chewed in the mouth emulges 
the falivary glands. 
3. The unwife cuftom of chewing and fmoking tobacco for 
many hours in a day not only injures the falivary glands, pro- 
ducing drynefs in the mouth when this drug is not ufed, but I 
fufpeCt that it allo produces feirrhus of the pancreas. The ufe 
of tobacco in this immoderate degree injures the power of di- 
geftion, by occafioning the patient to fpit out that faliva, which 
he ought to fwallow ; and hence produces that flatulency, which 
the vulgar unfortunately take it to prevent. The mucus, which 
is brought from the fauces by hawking, fhould be fpit out, as 
well as that coughed up from the lungs ; but that which comes 
fpontaneoufly into the mouth from the falivary glands, ihould 
be fwallowed mixed with our food or alone for the purpofes of 
digeftion. Sec Clafs I. 2. 2. 7. 
HI. 1. Expectorants are fuppofed to increafe the fecretion 
of mucus in the branches of the windpipe, or to increafe the 
perfpiration of the lungs fecreted at the terminations of the bron- 
chial artery. 
2. If any thing promotes expectoration toward the end of 
peripneumonies, when the inflammation is reduced by bleeding 
and gentle cathartics, fmall repeated blifters about the cheft, 
with tepid aqueous and mucilaginous or oily liquids, are more 
advantageous Art. III. 2. 3. 3. 
SECERNENTIA. 
37 
advantageous than the medicines generally enumerated under 
this head ; the blifters by ftimulatjng into a&ion the veflels of 
the Ikin produce by affociation a greater activity of thofe of 
the mucous membrane, which lines the branches of the wind- 
pipe, and air-cells of the lungs ; and thus after evacuation they 
promote the abforption of the mucus and contequent healing of 
the inflamed membrane, while the diluting liquids prevent this 
mucus from becoming too vifeid for this purpofe, or facilitate 
its expuition. 
Blifters, one at a time, on the fides or back, or on the fter- 
num, are alfo ufeful towards the end of peripneumonies, by pre- 
venting the evening accefs of cold fit, and thence preventing 
the hot fit by their ftimulus on the Ikin; in the fame manner 
as five drops of laudanum by its ftimulus on the ftomach. For 
the increafed actions of the veflels of the ikin or ftomach excite 
a greater quantity of the fenforial power of aflbeiation, and thus 
prevent the torpor of the other parts of the fyftem; which, 
when patients are debilitated, is fo liable to return in the 
evening. 
3. Warm bathing is of great fervice towards the end of perip- 
neumony to promote expectoration, efpecially in thofe children 
who drink too little aqueous fluids, as it gently increafes the 
action of the pulmonary capillaries by their content with the 
cutaneous ones, and fupplies the fyftem with aqueous fluid, and 
thus dilutes the fecreted mucus. 
Some have recommended oil externally around the cheft, as 
well as internally, to promote expectoration ; and upon the note, 
when its mucous membrane is inflamed, as in common catarrh. 
IV. 1. Diuretics. If the Ikin be kept warm, molt of thefe 
medicines promote fweat inftead of urine ; and if their dote is 
enlarged, moft of them become cathartic. Hence the neutral 
faits are uted in general for all thefe purpotes. Thofe indeed, 
which are competed of the vegetable acid, are moft generally 
uted as fudorifics; thofe with the nitrous acid as diuretics ; and 
thofe with the vitriolic acid as cathartics ; while thofe united 
with the marine acid enter our common nutriment, as a more 
general ftimulus. All thefe increate the acrimony of the urine, 
hence it is retained a lefs time in the bladder; and in conte- 
quence lefs of it is reabforbed into the fyftem, and the apparent 
quantity is greater, as more is evacuated from the bladder; but 
it is not certain from thence, that a greater quantity is fecreted 
by the kidneys. Hence nitre, and other neutral faits, are erro- 
neoufly given in the gonorrhoea; as they augment the pain of 
making wafer by their ftimulus on the excoriated or inflamed 
urethra. They are alfo erroneoufly given in catarrhs or coughs, 
where 38 
SECERNENTtA. 
Art. III. 2. 4. 2, 
where the difeharge is too thin and faline, as they increafe the 
frequency of coughing. 
2. Balfam of Copaiva is thought to promote urine more than 
the other native balfams ; and common refin is faid to aft as a 
powerful diuretic in horfes. Thefe are aifo much recommend- 
ed in gleets, and in fluor albus, perhaps more than they deferve ; 
they give a violet fmell to the urine, and hence probably increafe 
the Accretion of it. 
Calcined egg-lhells are faid to promote urine, perhaps front 
the phofphoric acid they contain. 
3. Cold air and cold water will increafe the quantity of urine 
by decreafmg the abforption from the bladder ; and neutral and 
alkalious faits and cantharides by ftimulating the neck of the 
bladder to difeharge the urine as ibon as fecreted ; and alcohol, 
as gin and rum, at the beginning of intoxication, if the body be 
kept cool, occafion much urine by inverting the urinary lymphat- 
ics, and thence pouring a fluid into the bladder, which never pair- 
ed the kidneys. But it is probable, that thofe medicines, which 
give a feent to the urine, as the balfams and refins, but particu- 
larly afparagus and garlic, are the only drugs, which truly increafe 
the fecretion of the kidneys. Alcohol however, ufed as above 
mentioned, and perhaps great dofes of tinfture of cantharides, 
may be conlidered as draftic diuretics, as they pour a fluid into 
the bladder by the retrograde aftion of the lymphatics, which 
are in great abundance fpread about the neck of it. See Seft. 
XXIX. 3. 
V. Mild Cathartics. The ancients believed that fome purg- 
es evacuated the bile, and hence were termed Cholagogues ; 
ethers the lymph, and were termed Hydragogues; and that in 
fnort each cathartic fclcftcd a peculiar humour, which it dif- 
charged. The moderns have too haftily rejefted this fyftem j 
the fubjeft well deferves further obfervation. 
Calomel given in the dofe from ten to twenty grains, fo as to 
induce purging without the afliftance of other drugs, appears to 
me to particularly increafe the fecretion of bile, and to evacuate 
it; aloe feems to increafe the fecretion of the inteftinal mucus; 
and it is probable that the pancreas and fpleen may be peculiarly 
ftimulated into aftion by fome other of this tribe of medicines ; 
whilft others of them may fimply ftimulate the inteftinal canal 
to evacuate its contents, as the bile of animals. It muft be re- 
marked, that all thefe cathartic medicines are fuppofed to be ex- 
hibited in their ufual dofes, otherwife they become draftic purg- 
es, and are treated of in the Clafs of Invertentia. 
VI. The mucus of the bladder is feen in the urine, when 
cantharides have been ufed, either internally or externally, in 
fuch Art. III. 2. 7.1. 
SECERNE^TIA. 
39 
fuch dofes as to induce the ftrangury. Spirit of turpentine is 
faid to have the fame effect. I have given above a dram of it 
twice a day floating on a glafs of water in chronic lumbago with- 
out this effect, and the patient gradually recovered. Phofpho- 
rus may poflibly affect the mucous glands of the urethra like 
cantharides. See Impotentia, Clafs II. 2. 2. 3. 
VII. Aloe given internally feems to a<Sl chiefly on the reftunl 
and fphiniter ani, producing tenefmus and piles. Externally in 
clyfters or fuppofitories, common fait feems to aft on that bow- 
el with greater certainty. But where the thread worms or afcar- 
ides exift, 60 or 100 grains of aloes reduced to powder and 
boiled in a pint of gruel, and ufed as a clyfter twice a week for 
three months, has frequently deftroyed them. Might not the 
hairs of filiqua hirfuta be ufed in an injection for this purpofe ? 
See Clafs I. 1. 4. 14. 
VIII. The external application of cantharides by ftimulating 
the excretory duffs of the capillary glands produces a great fe- 
cretion of fubcutaneous mucus with pain and inflammation; 
which mucaginous fluid, not being able to permeate the cuticle^ 
raifes it up; a fimilar fecretion and elevation of the cuticle is 
produced by actual fire j and by cauftic materials, as by the ap- 
plication of the juice of the root of white briony, or bruifed muf- 
tard-feed. Experiments are wanting to introduce fome acrid 
application into practice inftead of cantharides, which might not 
induce the ftrangury. 
Muftard-feed alone is too acrid, and if it be fullered to lie on. 
the Ikin many minutes is liable to produce a Hough and confe- 
quent ulcer, and Ihould therefore be mixed with flour when ap- 
plied to cold extremities. Volatile alkali properly diluted might 
ftimulate the fkin without inducing ftrangury. 
IX. The mild errhines are fuch as moderately ftimulate the 
membrane of the noftrils, fo as to increafe the fecretion of 
nafal mucus ; as is feen in thofe, who are habituated to take 
fnuff. The ftronger errhines are mentioned in Art. V. 2. 3. 
X. The fecretion of tears is increafed either by applying acrid 
fubftances to the eye ; or acrid vapours, which ftimulate the 
excretory duff of the lachrymal gland ; or by applying them to 
the noftrils, and ftimulating the excretory duff of the lachrymal 
fack, as treated of in the Section on Inftinft. 
Or the fecretion of tears is increafed by the affociation of the 
motions of the excretory duff of the lachrymal flick with ideas 
of tender pleafure, or of hopelefs diftrefs, as explained in Sett. 
XVI. 8. 2. and 3. 
XI. The fecretion of fenforial power in the brain is proba- 
bly increafed by opium or wine, becaufe when taken in certain 
Vol- I. R r r • quantity 40 
SECERNENTIA. 
Art. III. 1. 1. 1. 
quantity an immediate increafe of flrength and activity fucceeds 
for a time, with confequent debility if the quantity taken be fo 
great as to intoxicate in the leaft degree. The necellity of per- 
petual refpiration (hews, that the oxygen of the atmofphere fup- 
plies the fource of the fpirit of animation j which is conftantly 
expended, and is probably too fine to be long contained in the 
nerves after its production in the brain. Whence it is proba- 
ble, that the refpiration of oxygen gas mixed with common air 
mav increafe the fecretion of fcnforial power ; as indeed would 
appear from its exhilarating effeCt on molt patients. 
III. Catalogue of the Secernentia. 
I. Diaphoretics. 
i. Amomum zinziber, ginger. Carpophyllus aromati- 
cus, cloves. Piper indicum, pepper. Capficum. 
Cardamomum. Pimento, myrtus pimenta. Canella 
alba. Serpentaria virginiana, ariftolochia ferpenta- 
ria, guaiaciim. Saflafras, laurus faflafras. Opium. 
Wine. 
2. ElFential oils of cinnamon, laurus cinnamorftum. Nut- 
meg, myriftica mofchata. Cloves, caryophyllus aro- 
maticus. Mint, mentha. Camphor, laurus campho- 
fa. Ether. 
3. Volatile faits, as of ammoniac and of hartlhorn. Sal 
cornu cervi. 
4. Neutral faits, as thofe with vegetable acid; or with 
marine acid, as common fait. Halex, red-herring, 
anchovy. 
5. Preparations of antimony, as emetic tartar, antimoni- 
um tartarizatUm, wine of antimony. James's pow- 
der. 
6. External applications. Blifters. Warm bath. Warm 
air. Exercife. Friftion. 
7. Cold water with fubfequent warmths 
II. Sialagogues. Preparations of mercury, hydrargyrus. Py- 
rethrum, anthemis pyrethrum, tobacco, cloves, pepper, 
cowhage, ftizolobium fdiqua hirfuta. Maftich, pifta- 
cia lentifeus. 
III. Expectorants. 
1. Squill, fcilla maritima, garlic, leek, onion, allium, afa- 
feetida, ferula afafeetida, gum ammoniac, benzoin, 
tar, pix liquida, balfam of Tolu. 
2. Root of feneka, polygala feneka, of elecampane, inula 
helenium. 
3. Marfh-mallow Art. HI. 3. 3. 3. 
SECERNENTIA. 
41 
3- Marfh-mallow, althaea, coltsfoot, tuflilago farfara, gum 
arabic, mimofa nilotica, gum tragacanth, aftragalus 
tragacantha. Decoition of barley, hordeum diftichon. 
Exprefled oils. Spermaceti, foap. Extract of liquor- 
ice, glycyrrhiza glabra. Sugar. Honey. 
4. Externally blifters. Oil. Warm bath. 
(V. Mild diuretics. 
1. Nitre, kali acetatum, other neutral faits. 
2. Fixed alkali, foap, calcined egg-fhells. 
3. Turpentine. Balfam of Copaiva. Refin. Olibanum. 
4. Afparagus, garlic, wild daucus. Parfley, apium. Fen- 
nel, feniculum, pareira brava, ciflampelos ? 
5. Externally cold air, cold water. 
6. Alcohol. Tindiure of cantharides. Opium. 
V. Mild cathartics. 
1. Sweet fubacid fruits. Prunes, prunus domeftica. Caf- 
fia filtula. Tamarinds, cryftals of tartar, unrefined 
fugar. Manna. Honey. 
2. Whey of milk, bile of animals. 
3. Neutral faits, as Glauber's fait, vitriolated tartar, fea- 
water, magnefia alba, foap. 
4. Gum guaiacum. Balfam of Peru. Oleum ricini, 
caflor-oil, oil of almonds, oil of olives, fulphur. 
5. Senna, caffia fenna, jalap, aloe, rhubarb, rheum pal- 
matum. 
6. Calomel. Emetic tartar, antimonium tartarizatum. 
VI. Secretion of mucus of the bladder is increafed by can- 
tharides, by fpirit of turpentine ? Phofphorus ? 
VII. Secretion of mucus of the redlum is increafed by aloe 
internally, by various clyfters and fuppofitories externally. 
VIII. Secretion of fubcutaneous mucus is increafed by blif- 
ters of cantharides, by application of a thin flice of the 
frefh root of white briony, by finapifms, by root of horfe- 
radifh, cochlearia armoracia. Volatile alkali. 
IX. Mild errhines. Marjoram. Origanum. Marum, tobacco. 
X. Secretion of tears is increafed by vapour of diced onion, 
of volatile alkali. By pity, or ideas of hopelcfs didrefs. 
XI. Secretion of fenforial power in the brain is probably in- 
creafed by opium, by wine, and perhaps by oxygen gas 
added to the common air in refpiration. 
Art. 42 
SORBENTIA. 
Art. IV. 1. 1. 
Art. IV. 
SORBENTIA. 
I. Those things which increafe the irritative motions, 
which conftitute abforption, are termed forbentia; and are as 
various as the abforbent veflels which they ftimulate into action. 
i. Cutaneous abforption is increafed by auftere acids, as of 
vitriol; hence they are believed to check colliquative fweats, 
and to check the eruption of fmall-pox, and contribute to the 
cure of the itch, and tinea ; hence they thicken the faliva in 
the mouth, as lemon-juice, crab-juice, floes. 
2. Abiprptiomfrom the mucous membrane is increafed by opi- 
um, and Peruvian bark, internally ; and by blue vitriol externally. 
Hence the expectoration in coughs, and the mucous difcharge 
from the urethra, are thickened and leflened. 
3. Abforption from the cellular membrane is promoted by 
bitter vegetables, and by emetics, and cathartics. Hence mat- 
ter is thickened and leflened in ulcers by opium and Peruvian 
bark; and ferum is abforbed in anafarca by the operation of 
emetics and cathartics. 
4. Venous abforption is increafed by acrid vegetables ; as 
water-crefs, cellery, horfe-radiffi, muftard. Hence their ufe in 
fea-fcurvy, the vibices of which are owing to a defeat of ven- 
ous abforption j and by external ftimulants, as vinegar, and by 
electricity, and perhaps by oxygen. 
5. Inteftinal abforption is increafed by aftringent vegetables, 
as rhubarb, galls; and by earthy faits, as alum; and by argilla- 
ceous and calcareous earth. 
6. Hepatic abforption is increafed by metallic faits, hence 
calomel and fal martis are fo efficacious in jaundice, worms, 
chlorofis, dropfy. 
7. Venereal virus in ulcers is abforbed by the ftimulus of 
mercury ; hence they heal by the ufe of this medicine. 
8. Venefeclion, hunger, thirft, and violent evacuations, in- 
creafe all abforptions ; hence fweating produces coftivenefs. 
9. Externally bitter aftringent vegetables, earthy and metal- 
lic faits, and bandages, promote the abforption of the parts on 
which they are applied. 
10. All thefe in their ufual dofcs do not increafe the natur- 
al heat •, but they induce coftivenefs, and deep-coloured urine 
with earthy fediment. 
In greater dofes they invert the motions of the flomach and 
JaQeals ; and hence vomit or purge, as carduus benediftus, 
rhubarb. Art.IV. 2. 1.1. 
SORBENTIA. 
43 
rhubarb. They promote perfpiration, if the fkin be kept warm ; 
as camomile tea, and teftaceous powders, have been ufed as 
fudorifics. 
The preparations of antimony vomit, purge, or fweat, either 
according to the quantity exhibited, or as a part of what is giv- 
en is evacuated. Thus a quarter of a grain of emetic tartar (if 
well prepared) will promote a diaphorefis, if the fkin be kept 
warm; half a grain will procure a flool or two fir ft, and fweat- 
ing afterward ; and a grain will generally vomit, and then 
purge, and laftly fweat the patient. In lefs quantity it is prob- 
ble, that this medicine afts like other metallic faits, as fteel, 
zinc, or copper in fmall dofes ; that is, that it ftrengthens the 
fyftem by its ftimulus. As camomile and rhubarb in different 
dofes vomit, or purge, or act as ftimulants fo as to fLengthen 
the fyftem. 
Some of the medicines of this clafs of forbentia have been 
termed tonics by fome authors, as giving due tone to the ani- 
mal fibre. But it fhould be obferved, that tone is a mechanical 
term, applicable only to mufical firings, and like bracing and re- 
laxation, cannot be applied to animal life except metaphorically. 
The fame may be obferved of the word reaction, ufed by fome 
modern authors, which in its proper fignification is a mechan- 
ical term inapplicable to the laws of life except metaphorically. 
IL Observations on the Sorbentia. 
I, i. As there is great difference in the apparent ftruflure 
of the various glands, and of the fluids which they felecl from 
the blood, thefe glands muft poflefs different kinds of irritabili- 
ty, and are therefore ftimulated into ftronger or unnatural ac- 
tions by different articles of the materia medica, as fhewn in the 
fecernentia. Now as the abforbent veffels are likewife glands, 
and drink up or feleft different fluids, as chyle, water, mucus, 
with a part of every different Accretion, as a part of the bile, a 
part of the faliva, a part of the urine, &c. it appears, that thefe 
abforbent veffels muft likewife poffefs different kinds of irrita- 
bility, and in confequence muft require different articles of the 
materia medica to excite them into unufual action. This part 
of the fubject has been fo little attended to, that the candid 
reader will find in this article a great deal to excufe. 
it was obferved, that fome of the fecernentia did in a lefs de- 
gree increafe abforption, from the combination of different prop- 
erties in the fame vegetable body ; for the fame reafon fome of 
the clafs of forbentia produce Accretion in a leAs degree, as thoAe 
bitters which have alfo an aroma in their compofition ; thefe 
ate 44 
SORBENTIA. 
Art. IV. 2. i. 2. 
are known from their increafing the heat of the fyftem above 
its ufual degree. 
It muft alfo be noted, that the adlions of every part of the 
abforbent fyftem are fo aflbciated with each other, that the 
drugs which ftimulate one branch increafe the adlion of the 
whole ; and the torpor or quiefcence of one branch weakens the 
exertions of the whole ; or when one branch is excited into 
ftronger action, fome other branch has its actions weakened or 
inverted. Yet though peculiar branches of the abforbent fyf- 
tem are ftimulated into action by peculiar fubftances, there are 
other fubftances which feem to ftimulate the whole lyftem, and 
that without immediately increafing any of the fecretions ; as 
thofe bitters which poflefs no aromatic fcent, at the head of 
which (lands the famed Peruvian bark, or cinchona. 
2. Cutaneous abforption. I have heard of fome experi- 
ments, in which the body was kept cold, and was thought to 
abforb more moifture from the atmofphere than at any other 
time. This however cannot be determined by ftatical experi- 
ments ; as the capillary veflels, which fecrete the perfpirable 
matter, muft at the fame time have been benumbed by the cold; 
and from their inadlion there could not have been the ufual 
wafte of the weight of the body j and as all other mufcular ex- 
ertions are belt performed, wh£n the body poflefles its ufual de- 
gree of warmth, it is conclufive, that the abforbent fyftem ftiould 
likewife do its office beft, when it is not benumbed by external 
cold. 
The auftere acids, as of vitriol, lemon-juice, juice of crabs and 
floes, ftrengthen digeftion, and prevent that propenfity to fweat 
fo ufual to weak convalefcents, and diminiffi the colliquative 
fweats in hedtic fevers ; all which are owing to their increafing 
the action of the external and internal cutaneous abforption. 
Hence vitriolic acid is given in the fmall-pox to prevent the too 
hafty or too copious eruption, which it eftedls, by increafing the 
cutaneous abforption. Vinegar, from the quantity of alcohol 
which it contains, exerts a contrary effedl to that here defcrib- 
cd, and belongs to the incitantia ; as an ounce of it promotes 
fweat, and a flufhing of the Ikin ; at the fame externally it adds 
as a venous abforbent, as the lips become pale by moiftening 
them with it. And it is faid, when taken internally in great 
and continued quantity, to induce palenefs of the ikin, and foft- 
nefs of the bones. 
The fweet vegetable acids, as of feveral ripe fruits, are among 
the torpentia ; as they are lefs ftimulating than the general food 
of this climate, and are hence ufed in inflammatory difeafes. 
Where the quantity of fluids in the fyftem is much leflened, 
as Art. IV. 2. i. 3* 
SORBENTIA. 
45 
as in heCtic fever, which has been of fome continuance, or in 
fpurious peripneumony, a grain of opium given at night will 
fometimes prevent the appearance of fwcats; which is owing to 
the ftimulus of opium increafing the actions of the cutaneous 
abforbents, more than thofe of the fecerning vefl'cls of the Ikin. 
Whence the fecretion of perfpirable matter is not decreafed, 
but its appearance on the Ikin is prevented by its more facile 
abforption. 
3. There is one kind of itch, which feldom appears between 
the fingers, is the leaft infectious, and moft difficult to eradicate, 
and which has its cure much facilitated by the internal ufe of 
acid of vitriol. This difeafe confifts of fmall ulcers in the fkin, 
which are healed by whatever increafes the cutaneous abforp- 
tion. The external application of fulphur, mercury, and acrid 
vegetables, ads on the fame principle ; for the animalcula, 
which are feen in thefe puftules, are the effect, not the caufe, of 
them ; as all other ftagnating animal fluids, as the femen itfelf, 
abounds with fimilar microfcopic animals. See Dyfentery, 
Clafs II. 1. 3. i8» * 
4. Young children have fometimes an eruption upon the head 
called tinea, which difcharges an acrimonious ichor inflaming 
the parts, on which it falls. This eruption I have feen fubmit 
to the internal ufe of vitriolic acid, when only wheat-flour was 
applied externally. This kind of eruption is likewife frequent- 
ly cured by teftaceous powders ; two materials fo widely differ- 
ent in their chemical properties, but agreeing in their power of 
promoting cutaneous abforption. 
II. Abforption from the mucous membrane is increafed by 
applying to its furface the auftere acids, as of vitriol, lemon-juice, 
crab-juice, floes. When thefe are taken into the mouth, they 
immediately thicken, and at the fame time leflen the quantity of 
the faliva; which laft circumftance cannot be owing to their 
coagulating the faliva, but to their increafing the abforption of 
the thinner parts of it. So alum applied to the tip of the tongue 
does not flop in its action there, but independent of its diffufion 
it induces cohefion and corrugation over the whole mouth. (Cul- 
len's Mat. Med. Art. Aftringentia.) Which is owing to the 
aflociation of the motions of the parts or branches of the abforb- 
cnt fyftem with each other. 
Abforption from the mucous membrane is increafed by opium 
taken internally in fmall dofes more than by any other medicine, 
as is feen in its thickening the expectoration in coughs, and the 
difcharge from the noftrils in catarrh, and perhaps the difcharge 
from the urethra in gonorrhoea. The bark feems next in pow- 
er for all thefe purpofes. 
Externally 46 
sorblntia. 
AHT. IV. 2. 3. t. 
Externally flight folutions of blue vitriol, as two or three 
grains to an ounce of water, applied to ulcers of the mouth, or 
to chancres on the glans penis, more powerfully induce them to 
heal than any other material. 
Where the lungs or urethra are inflamed to a confiderable 
degree, and the abforption is fo great, that the mucus is already 
too thick, and adheres to the membrane from its vifeidity, opi- 
ates and bitter vegetable and auftere acids are improper ; and 
mucilaginous diluent fhould be ufed in their (lead with venefee- 
tion and torpentia. 
III. I. Abforption from the cellular membrane, and from all 
the other cavities of the body, is too flowly performed in fome 
ebnftitutions ; hence the bloated pale complexion ; and when 
this occurs in its greateft degree, it becomes an univerfal dropfy. 
Thefe habits are liable to intermittent fevers, hyfteric paroxyfms, 
cold extremities, indigeftion, and all the fymptoms of debility. 
The abforbent fyftem is more fubjeft to torpor or quiefccnce 
than tire leeerning fyftem, both from the coldnefs of the fluids 
which are applied to it, as the moifture of the atmofphcre, and 
from the coldnefs of the fluids which we drink ; and alfo from 
its being ftimulated only by intervals, as when we take our food > 
whereas the fecerning fyftem is perpetually excited into action 
by the warm circulating blood ; as explained in Sedl. XXXII. 
2. The Peruvian bark, camomile flowers, and other bitter 
drugs, by ftimulating this cellular branch of the abforbent fyftem 
prevents it from becoming quiefeent •, hence the cold paroxyfms 
of thofe agues, which arife from the torpor of the cellular lymph- 
atics, are prevented, and the hot fits in confequence. The 
patient thence preferves his natural heat, regains his healthy 
colour, and his accuftomed ftrength. 
Where the cold paroxyfm of an ague originates in the abforb- 
ents of the liver, fpleen, or other internal vifeus, the addition of 
fteel to vegetable bitters, and efpecially after the ufe of one 
dofe of calomel, much advances the cure. 
And where it originates in any part of the fecerning fyftem, 
as is probably the cafe in fome kinds of agues, the addition of 
opium in the dofe of a grain and half, given about an hour be- 
fore the accefs of the paroxyfm, or mixed with chalybeate and 
bitter medicines, enfures the cure. Or the fame may be effected 
by wine given inftead of opium before the paroxyfm, fo as near- 
ly to intoxicate. 
Thefe three kinds of agues arc thus diftinguifhed ; the firft is 
not attended with any tumid or indurated vifeus, which the peo- 
ple call an ague cake, and which is evident to the touch. The 
fecond is accompanied with a tumid vifeus j and the laft has 
generally. Art. IV. 2. 3.3* 
SORBENT1A. 
47 
generally, I believe, the quartan type, and is attended with forhe 
degree of arterial debility. 
The bark of the broad-leaved willow or falixeaprea of Linnet 
us, is much recommended as equal to the Peruvian bark given 
in the fame or in greater quantity by Mr. White of Bath. Ob- 
ferV. and Expcr. on broad-leafed willow. Vernor and Hood, 
London. A Dr. Gunz in Germany recommends alfo as a fub- 
flitute for Peruvian bark, the bark of fix fpecies of willow, the 
falix alba, pentandra, fragilis, caprea, vitellina, and amygdalinas. 
Dr. Gunz believes fome of thefe barks to be more elhcacious 
than the Peruvian. And as fome of thefe willow-barks may bd 
procured in great quantity, as they are ftripped off from the wil- 
low twigs ufed by the bafket-makers in many parts of the coun- 
try in the vernal months, it would feem to be an article worth 
tittending to. 
The root of geum urbanUm, avens, is recommended as a fub- 
ftitute for Peruvian bark by Dr. Vogel, and faid to cure the 
quartan ague given in the dofe of half a dram every hour through 
the day. The datifea cannabina of Linneus is alfo faid to equal 
the Peruvian bark in its febrifuge virtues. Medical and Phyfical 
Journal, Vol. I. p. ipi. 
3. This clafs of abforbent medicines are faid to decreafe irri- 
tability. After any part of our fyftem has been torpid or qui- 
efoent, by whatever caufe that was produced, it betomds after- 
wards capable of being excited into greater motion by fmall 
ftimuli; hence the hot fit of fever fuceeeds the cold One. As 
thefe medicines preVent torpor or quiefcence of parts of the fyf- 
tem, as cold hands or feet, which perpetually happen to Weak 
conftitutions, the fubfequent increafe Of irritability of thefe parts 
is likewife prevented. 
4. Thefe abforbent medicines, including both the bitters, 
and metallic faits, and opiates, are of great ufe in the dropfy by 
their promoting univerfal abforption ; but here evacuations are 
likewife to be produced, as will be treated of in the Invertentia. 
5. The matter in ulcers is thickened, and thence rendered. 
Jefs cofrofive, the faline part of it being reabforbed by the ufe 
of bitter medicines : hence the bark is ufed with advantage in 
the cure of ulcers. 
6. Bitter medicines ilrengthen digeftion by promoting the 
abforption of chyle ; hence the introduction of hop into the po- 
tation ufed at our meals, which as a medicine may be taken ad- 
vantageoufly, but, like other unneccffary ftimuli, mult be injuri- 
ous as an article of out daily diet. 
'Phe hop may perhaps in fome degree contribute to the pro- 
diufiion of gravel in the kidneys, as our intemperate wine-drink- 
VoLi L 8 3 f ers 48 
SORBENHA. 
Art. IV. 2. 3. 7. 
crs are more fubjeCl to the gout, and ale-drinkers to the gravel; 
in the formation of both which difeafes, there can be no doubt, 
but that the alcohol is the principal, if not the only agent. 
7. Vomits greatly increafe the abforption from the cellular 
membrane, as fquill, and foxglove. The fquill fhould be given 
in the dofe of a grain of the dried root every hour, till it ope- 
rates upwards and downwards. Four ounces of the freffi leaves 
of the foxglove fhould be boiled from two pounds of water to 
one, and half an ounce of the decoCtion taken every two hours 
for four or more dofes. This medicine by ftimulating into in- 
verted a&ion the abforbents of the ftomach, incrcafes the direct 
aCtion of the cellular lymphatics. 
Another more convenient way of afeertaining the dofe of 
foxglove is by making a faturated tincture of it in proof fpirit ; 
which has the twofold advantage of being invariable in its origin- 
al ftrength, and of keeping a long time as a fhop-medicine 
without lofmg any of its virtue. Put two ounces of the leaves 
of purple foxglove, digitalis purpurea, nicely dried, and coarfely 
powdered, into a mixture of four ounces of rectified fpirit of 
wine and four ounces of water 5 let the mixture Rand by the 
fire-fide twenty-four hours frequently (baking the bottle, and 
thus making a faturated tindure of digitalis ; which mud bt 
poured from the fediment or palled through filtering paper. 
Some perfon has lately objected to the quantity of the dried 
leaves of digitalis ufed in this tincture as an unneceffary ex- 
penfe; not knowing that the plant grows fpontaneoufly by cart- 
loads in all fandy Situations, and not recollecting that the cer- 
tainty of procuring this medicine at all times of the year, and 
from all (hops of the fame degree of ftrength, is a circumftance 
of great importance. 
As the fize of a drop is greater or lefs according to the fize of 
the rim of the phial from which it is dropped, a part of this 
faturated tinClure is then directed to be put into a two-ounce 
phial, for the purpofe of afeertaining the fize of the drop. 
Thirty drops of this tincture are directed to be put into an 
ounce of mint-water for a draught to be taken twice or thrice 
a day, till it reduces the anafarca of the limbs, or removes the 
difficulty of breathing in hydrothorax, or till it induces fickncfs. 
And if thefe do not occur in two or three days, the dofe muft 
be gradually increafed to forty or fixty drops, or further. 
A ladv, who was 92 years of age, was feized fuddenly, early 
in the morning, with great difficulty of refpiration, which con- 
tinued in greater or lefs degree in fpite of many medicines for 
two or three weeks. Her legs were then become oedematous, 
and (he could not lie down horizontally. On taking thirty 
drops Art. IV. 2.3. 8. 
SORBENTIA. 
49 
drops of the faturated tinQure of digitalis from a two-ounce 
phial twice a day, (he became free from the difficult refpira- 
tion, and her legs became lefs fwelled, in two or three days. 
She has repeated this medicine about once a month for more 
than a year, with tinflure of bark at intervals, and half a grain 
of opium at night, and retains a tolerable Hate of health. 
From the great ftimulus of this medicine the ftomach is ren- 
dered torpid with confequent ficknefs, which continues many 
hours and even days, owing to the great exhauftion of its fenfo- 
rial power of irritation ; and the action of the heart and arteries 
becomes feeble from the deficient excitement of the fenforial 
power of aflbeiation 5 and laftly, the abforbents of the cellular 
membrane aft more violently in confequence of the accumula- 
tion of the fenforial power of aflbeiation in the torpid heart and 
arteries, as explained in Suppl. I. 12. 
A circumllance curioufly fimilar to this occurs to fome peo- 
ple on fmoking tobacco for a fhort time, who have not been ac- 
cuftomed to it. A degree of ficknefs is prefently induced, and 
the pulfations of the heart and arteries become feeble for a fhort 
time, as in the approach to fainting, owing to the direct fym- 
pathy between thefe and the ftomach, that is from defeft of 
the excitement of the power of aflbeiation. Then there fuc- 
ceed a tingling, and heat, and fometimes fweat, owing to the in- 
creafed action of the capillaries, or perfpirative and mucous 
glands ; which arc occafioncd by the accumulation of the fen- 
forial power of aflbeiation by the weaker action of the heart and 
arteries, which now increafes the ablion of the capillaries. 
8. Another method of mcreafing abforption from the cellu- 
lar membrane is by warm air, or by warm fleam. If the fwell- 
ed legs of a dropfical patient are enclofed in a box, the air of 
which is made warm by a lamp or two, copious fweats are foon 
produced by the increafed ablion of the capillary glands, which 
are feen to fland on the fkin, as it cannot readily exhale in fo 
fmall a quantity of air, which is only changed fo faft as may be 
neceflary to permit the lamps to burn. At the fame time the 
lymphatics of the cellular membrane are ftimulated by the heat 
into greater action, as appears by the fpeedy reduction of the 
tumid legs. 
It would be well worth trying an experiment upon a perfon 
labouring under a general anafarca by putting him into a room 
filled with air heated to 120 or 130 degrees, which would prob- 
ably excite a great general diaphorefis, and a general cellular ab- 
forption both from the lungs and every other part. And that 
air of fo great heat may be borne for many minutes without 
great 50 
SORBLNTIA- 
Art. IV. 2, 3. 9. 
great inconvenience was fhewn by the experiments made in 
heated rooms by Dr. Fordyce and others. Philof, Tranf. 
Another experiment of ufing warmth in anafarca, or in oth- 
er difeafes, might be by immetfing the patient in warm air, or 
in warm Ream, received into an oil-fkin hag, or bathing-tub of 
tin, fo managed, that the current of warm air or fteam fhould 
pafs round aqd cover the whole of the body except the head, 
which might not be expofed to jt; and thus the abforbents of 
the lungs might be induced to aft more powerfully by fympa-* 
thy with the fkin, and not by the ftimulus of heat. See Ufeg 
of Warm Bath, Art. II. 2. 2. I. 
A warm faline pediluvium has often been ufed with fuccels 
to remove fwellings of the legs from deficient action of the ab- 
forbents of the lower extremities; the quantity of fea-falt fhould 
fie about one thirtieth part of the water, which with about one 
eightieth part of fulphuric magnefian fait, called magnefla vitri- 
data, or bitter cathartic fait, conftitutes the medium ftrength of 
the fea-water round this ifland, according to the experiments of 
Mr. Brownrig. In fuch a pediluvium the fwelled legs Ihould 
be immerfed for half an hour every night for a fortnight, at the 
heat of about 90 or 98 degrees. 
Dr. Reid, in a Treatife on Sea-bathing ; Cadell and Davis, 
London ; recommends an univerfal warm-bath of fea-water, in 
oedematous fwellings, apparently with great fuccefs, and well 
advifes friflion to be diligently ufed in the bath on the tumid 
limbs, always rubbing them from their extremities towards the 
trunk of the body, and not the contrary way ; as this mult moff 
facilitate the progrefs of the fluids in the abforbent fyilein ; 
though thefe veflels are furnifhed with valves to prevent its re- 
turn. In thefe baths the ftimulus of the fait is added to that of 
the heat. See Art. II. 2. 2. 1. 
9. Another method of increafing abforption from the celhu 
lar membrane, which has been ufed in dropfics, has been by the 
great or total abflincnce from fluids. This may in fome degree 
be ufed advantageoufly in fubjecSts of too great corpulency, but 
if carried to cxcefs may induce fevers, and greater evils than 
it is defigned to counteract, befjdes the perpetual exiftence 
of a painful thirft. In molt dropfies the thirft already exifting 
(hews, that too little diluent fluid, and not too much, is prefent 
in the circulation. 
IV. 1. Venous abforption. Cellery, watercretTes, cabbages, 
and many other vegetables of the clafs tetradynamia, do not in- 
create the heat of the body (except thofe, the acrimony of which, 
approaches to corrofion), and hence they feem alone, or princL 
pally, to aft on the venous fyllem ; the extremities of which we 
have Art. IV. 2.4.2. 
SORBENTIA. 
51 
have (hewn are abforbents of the red blood, after it has paflcd 
the capillaries and glands. 
2. In the fea-fcurvy and petechial fever the veins do not per- 
fectly perform this office of abforption ; and hence the vibices 
are occafioned by blood ftagnating at their extremities, or ex- 
travafated into the cellular membrane. And this clafs of vegeta- 
bles, ftimulating the veins to perform their natural abforption, 
without increafing the energy of the arterial aClion, prevents 
future petechiae, and may affift the abforption of the blood al- 
ready fiagnated,as foon as its chemical change renders it proper 
for that operation. 
3. The fluids, which are extravafated, and received into the 
cells of the cellular membrane, feem to continue there for many 
days, fo as to undergo fome chemical change, and are then taken 
up again by the mouths of the cellular abforbents. But the 
new veflels produced in inflamed parts, as they communicate 
with the veins, are probably abforbed again by the veins along 
with the blood which they contain in their cavities. Hence the 
blood, which is extravafated in bruifes of vibices, is,gradually 
many days in difappearing; but after due evacuations the in- 
flamed veflels on the white of the eye, if any ftimulant lotion is 
applied, totally difappear in a few hours. 
Amongft abforbents affefting the veins we fhould therefore 
add the external application of flimulant materials ; as of vine- 
gar, which makes the lips pale on touching them. Friction, 
and electricity. 
4. Haemorrhages are of two kinds, either arterial, which arc 
attended with inflammation ; or venous, from a deficiency in 
the abforbent power of this fet of veflels. In the former cafe 
the torpentia are efficacious ; in the latter fleel, opium, alum, 
and all the tribe of forbentia, are ufed with fuccefs. 
5. Sydenham recommends vegetables of the clafs tetradyna- 
mia in rheumatic pains left after the cure of intermittents. 
Thefe pains are perhaps fimilar to thofe of the fea-fcurvy, and 
feem to arife from want of abforption in the afieCled part, and 
hence are relieved by the fame medicines. 
V. 1. Inteftinal abforption. Some afiringent vegetables, as 
yhubatb, may be given in fuch doles as toprove cathartic ; and, 
after a part of it is evacuated from the body, the remaining 
part augments the abforption of the inteftines ; and acls, as if 
a fimilar dofe had been exhibited after the operation of any oth- 
er purgative. Hence 4 grains of rhubarb tirengthen the bow- 
els, 30 grains firft empty them. 
2, The earthy faits, as alum, increafe the inteftinal abforp- 
tiemj and hence induce conflipation in their ufual dole; alum 
is 52 
SORBENTIA. 
Art. IV. 2. 5. 3. 
is faid fometimes to cure intermittents, perhaps when their feat 
is in the inteftines, when other remedies have failed. It is ufe- 
ful in the diabetes, by exciting the abforbents of the bladder in- 
to their natural action ; and combined with refm is efteemed 
in the fluor albus, and in gleets. Lime-ftone or chalk, and 
probably gypfum, poflefs effects in fome degree fimilar, and in- 
creafe the abforption of the inteftines ; and thus in certain do- 
fes reftrain fome diarrhoeas, but in greater dofes alum I fup- 
pofe will aft as a cathartic. Five or ten grains produce confti- 
pation, 20 or 30 grains are either emetic or cathartic. 
3. Earth of alum, tobacco-pipe clay, marl, Armenian bole, 
lime, crab's eyes or claws, and calcined hartfhorn, or bone alli- 
es, reftrain fluxes ; either mechanically by fupplying fomething 
like mucilage, or oil, or rollers to abate the friction of the ali- 
ment over inflamed membranes ; or by increafing their abforp- 
tion. The two laft confift of calcareous earth united to phof- 
phoric acid, and the Armenian bole and marl may contain iron. 
By the confent between the inteftines and the fkin 20 grains of 
Armenian bole given at going into bed to hectic patients will 
frequently check their tendency to fweat as well as to purge, 
and the more certainly if joined with one grain of opium. 
VI. 1. Abforption from the liver, ftomach, and other vifeera. 
When inflammations of the liver are fubdued to a certain de- 
gree by venefeftion, with calomel and other gentle purges, fo 
that the arterial energy becomes weakened, four or eight grains 
of iron-filings, or of fait of fteel, with the Peruvian bark, have 
wonderful effect in curing the cough, and reftoring the liver to 
its ufual fixe and fanity ; which it feems to effect by increafing 
the abforption of this vifeus. The fame I fuppofe happens in 
refpeft to the tumours of other vifeera, as of the fpleen, or pan- 
creas, fome of which are frequently enlarged in agues. 
2. Haemorrhages from the nofe, reffum, kidneys, uterus, and 
other parts, are frequently attendant on difeafed livers ; the 
blood being impeded in the vena portarum from the decreafed 
power of abforption, and in confequence of the increafed fize of 
this vifeus. Thefe haemorrhages after venefe&ion, and a mer- 
curial cathartic, are moft certainly reftrained by fteel alone, or 
joined with an opiate ; which increafe the abforption and di- 
minifh the fize of the liver. 
Chalybeates may alfo reftrain thefe haemorrhages by their 
promoting venous abforption, though they exert their principal 
effect upon the liver. Hence alfo opiates, and bitters, and vit- 
riolic acid are advantageouily ufed along with them. It muff: 
be added that fome haemorrhages recur by periods like the par- 
ox yim^ Art. IV. 2. 6. 3. 
SORBENTIA. 
53 
oxyfms of intermittent fevers, and are thence cured by the fame 
treatment. 
3. The jaundice is frequently caufed by the infipidity of the 
bile, which does not ftimulate the gall-bladder and bile-ducts in- 
to their due action ; hence it ftagnates in the gall-bladder, and 
produces a kind of cryftallization, which is too large to pafs in- 
to the inteftines, blocks up the bile-dutl, and occafions a long 
and painful difeafe. A paralyfis of the bile-du6t produces a 
fimilar jaundice, but without pain. 
4. Worms in (heep called Hukes are owing to the dilute 
Rate of the bile; hence they originate in the inteftines, and 
thence migrate into the biliary du£ts, and corroding the liver 
produce ulcers, cough, and heeftic fever, called the rot. In hu- 
man bodies it is probable the inert ftate of the bile is one caufe 
of the production of worms; which infipid ftate of the bile is 
owing to deficient abforption of the thinner parts of it; hence 
the pale and bloated complexion, and fwelled upper lip, of wormy 
children, is owing to the concomitant deficiency of abforption 
from the cellular membrane. Salt of fteel, or the ruft of it, or 
filings of it, with bitters, increafe the acrimony of the bile by 
promoting the abforption of its aqueous part; and hence deftroy 
worms, as well by their immediate action on the inteftines, as 
on the worms themfelves. The cure is facilitated by premi- 
fing a purge with calomel. See Clafs I. 2. 3. 9. 
5. The chlorofis is another difeafe owing to the deficient ac- 
tion of the abforbents of the liver, and perhaps in feme degree 
alfo to that of the fecretory veflels, or glands, which compofe 
that vifeus. Of this the want of the catamenia, which is gen- 
erally fuppofed to be a caufe, is only a fymptom or confequence. 
In this complaint the bile is deficient perhaps in quantity, but 
certainly in acrimony, the thinner parts not being abforbed from 
it. Now as the bile is probably of great confequence in the pro- 
cefs of making the blood ; it is on this account that the blood 
is fo deftitute of red globules ; which is evinced by the great 
palenefs of thefe patients. As this fcrous blood muft exert lefs 
ftimulus on the heart, and arteries, the pulfe in confequence 
becomes quick as well as weak, as explained in Sedl. XII. 1. 4. 
The quicknefs of the pulfe is frequently fo great and perma- 
nent, that when attended by an accidental cough, the difeafe 
may be miftaken for hecftic fever ; but is cured by chalybeates, 
and bitters exhibited twice a dav ; with half a grain of opium, 
and a grain of aloe every night; and the expelled catamenia 
appears in confequence of a reftoration of the due quantity of 
red blood. This and the two former articles approach to the 
difeafe termed paralyfis of the liver. Seii. XXX. 4. 
a. it 54 
SOHBENTIA. 
Art. IV. 2. 6. & 
6. It feeiYiB paradoxical, that the fame treatment with chalyb- 
eates, bitters, and opiates, which produces menftruation in chlo- 
rotic patients, fhould reprcfs the too great or permanent men* 
ftruation, which occurs in weak conftitutions at the time of life 
when it fhould ceafe. This complaint is a haemorrhage owing 
to the debility of the abforbent power of the veins, and belongs 
to the paragraph on venous abforption above defcribed, and is 
thence curable by chalybeates, alum, bitters, and particularly by 
the exhibition of a grain of opium every night with five grains 
of rhubarbs 
As fteel is foluble in the gaftric acid, perhaps thebefl way of 
giving it may be in fine filings, or in a ftecl-powder prepared in 
the following manner : difiblve green vitriol in water, add a few 
bits of iron to the folution, to precipitate any copper which 
may be accidentally in it; precipitate this folution by fait of tar- 
tar, kali preparatum. Add to the precipitate two or three times 
its quantity of charcoal powder, mix and put them into a cruci- 
ble covered with a tile, and give them a ted heat for an hour. 
An impalpable powder of iron will be produced, which ought 
all of it to obey the magnet. 
7. Metallic faits fupply us with, very powerful remedies for 
promoting abforption in dropfical cafes; which frequently are 
can fed by enlargement of the liver. Fir ft, as they may be giv- 
en in fuch quantities as to prove flrongly cathartic, of which 
more will be laid in the article on invertentia •, and then, when 
their purgative quality ceafes, like the effect of rhubarb, their ab- 
forbent quality continues to act. The faits of mercury, hlver* 
copper, iron, zinc, antimony, have all been ufed in the dropfy ; 
either fingly for the former purpofe, or united with bitters for 
the latter, and occafionally with moderate but repeated opiates. 
8* From a quarter of a grain to half a grain of blue vitriol 
given every four or fix hours, is faid to be very efficacious in ob- 
ftinate intermittents ; which alfo frequently arife from an en- 
larged vifeus, as the liver or fpleen, and are thence owing to the 
deficient abforption of the lymphatics of that vifeus. A quarter 
of a grain of white arfenic, as I was informed by a furgeon of the 
army, cures a quartan ague with great certainty, if it be given 
an hour before the expelled fit. This dofe he faid was for a ro- 
bufl man, perhaps one eighth of a grain might he given and re- 
peated with greater fafety and equal efficacy. 
Dr. Fowler has given many fuccefsful cafes in his treatife 
on this fubjetl. He prepares it by boiling fixty-four grains of 
white arfenic in a Florence flalk along with as much pure vegeta- 
ble fixed alkali in a pint of diltilled water till they are diflblv- 
ed, and then adding as much diltilled water as will make the 
whole AkT. IV. 2.6.9. 
SORBENTIA. 
55 
whole exactly fixteen ounces. Hence there are four grains of 
arfenic in every ounce of the folution. This fhould be put into a 
phial of fuch a fize of the edge of its aperture, that fixty drops 
may weigh one dram, which will contain half a grain of arfenic. 
To children from two years old to four he gives from two to five 
drops three or four times a day. From five years old to feven, 
he dirfts feven or eight drops. From eight years old to twelve, 
he directs from feven to ten drops. From thirteen years old to 
eighteen he directs from ten to twelve drops. From eighteen 
upwards, twelve drops. In fo powerful a medicine it is always 
prudent to begin with fmaller dofes, and gradually to increafe 
them. 
A faturated folution of arfenic in water is preferable 1 think 
to the above operofe preparation of it; as no error can happen 
in weighing the ingredients, and it more certainly therefore pof- 
fefles an uniform ftrength. Put much more white arfenic re- 
duced to powder into a given quantity of diftilled water, than 
can be diflblved in it. Boil it for half an hour in a Florence 
flalk, or in a tin fauce-pan; let it ftand to fubfide, and filter 
it through paper. My friend Mr. Greene, a furgeon at Bree- 
wood in Staffordfhire, aflured me, that he had cured in one fea- 
fon agues without number with this faturated folution ; that he 
found ten drops from a two-ounce phial given thrice a day was 
a full dofe for a grown perfon, but that he generally began 
with five. 
9. The manner, in which arfenic a£ts in curing intermittent 
fevers cannot be by its general ftimulus, becaufe no intoxication 
or heat follows the ufe of it; nor by its peculiar ftimulus on 
any part of the fecreting fyftem, fince it is not in fmall dofes 
fucceeded by any increafed evacuation, or heat, and muft there- 
fore exert its power, like other articles of the forbentia, on the 
abforbent fyftem. In what manner it deftroys life fo fuddenly 
is difficult to underftand, as it does not intoxicate like many 
vegetable poifons, nor produce fevers like contagious matter. 
When applied externally it feems chemically to deftroy the part 
like other cauftics. Does it chemically deftroy the ftomach, 
and life in confequence ? or does it deftroy the action of the 
ftomach by its great ftimulus, and life in confequence of the 
fympathy between the ftomach and the heart ? This laft appears 
to be the moft probable mode of its operation. 
The fuccefs of arfenic in the cure of intermittent fevers I fuf- 
pe<fi to depend on its ftimulating the ftomach into ftronger ac- 
tion, and thus, by the aflbeiation of this vifeus with the heart 
and arteries, preventing the torpor of any part of the fangtiii- 
Vol. I- T T t erous 56 
SORBENTIA. 
Art. IV. 2. 6. 
erous fyftem. I was led to this conclufion from the following 
confiderations. • 
Firft. The effects of arfenic given a long time internally in 
fmall dofes, or when ufed in larger quantities externally feem 
to be fimilar to thofe of other great ftimuli, as of wine or alco- 
hol. Thefe are a bloated countenance, fwelled legs, hepatic tu- 
mours, and dropfy, and fometimes eruptions on the fkin. The 
former of thefe I have feen, where arfenic has been ufed external- 
ly for curing the itch ; and the latter appears on evidence in the 
famous trial of Mifs Blandy at Chelmsford, about forty years ago. 
Secondly. I faw an ague cured by arfenic in a child, who 
had in vain previoufly taken a very large quantity of bark with 
great regularity. And another cafe of a young officer, who had 
lived intcmperately, and laboured under an intermittent fever, 
and had taken the bark repeatedly in confiderable quantities, 
with a grain of opium at night, and though the paroxyfms had 
been thrice thus for a time prevented, they recurred in about a 
week. On taking five drops of a faturated folution of arfenic 
thrice a day the paroxyfms ceafed, and returned no more, and 
at the fame time his appetite became much improved. 
Thirdly. A gentleman about fixty-five years of age had for 
about ten years been fubject to an intermittent pulfe, and to 
frequent palpitations of his heart. Lately the palpitations 
feemed to obferve irregular periods, but the intermiffion of eve- 
ry third or fourth pulfation was almoft perpetual. On giving 
him four drops of a faturated folution of arfenic from a two- 
ounce phial almoft every four hours for one day, not only the 
palpitation did not return, but the intermiffion ceafed entirely, 
and did not return fo long as he took the medicine, which was 
three or four days. 
Nowr as wdien the ftomach has its action much weakened by 
an over-dofe of digitalis, the pulfe is liable to intermit, this evin- 
ces a <lire£t fympathy between thefe parts of the fyftem ; and 
as I have repeatedly obferved, that when the pulfe begins to in- 
termit in elderly people, that an eructation from the ftomach, 
voluntarily produced, will prevent the threatened ftop of the 
heart ; 1 am induced to think, that the torpid ftate of the ftom- 
ach, at the inftant of the production of air occafioned by its 
weak action, caufed the intermiffion of the pulfe. And that 
arfenic in this cafe, as well as in the cafes of agues above men- 
tioned, produced its effects by ftimulating the ftomach into more 
powerful aftion; and that the equality of the motions of the 
heart was thus reftored by increafmg the excitement of the fen- 
forial povrer of affociation. See Sect. XXV. 17* Clafs IV. 
2. 1. x8. 
Arfenic Art. IV. 2. 7. 1. 
SORBENTIA. 
57 
Arfenic has lately been recommended in the hooping cough, 
tuffis convulfiva, by Mr. Simmons, furgeon of Manchefter, 
which he afferts to be attended with the molt falutary effects, 
moderating the difeafe in a few days, and curing it generally in 
a fortnight. He has given it to children of a year old with fafe- 
ty, in the dofes recommended by Dr. Fowler, whofe folution 
he ufed, but fcems to have ufed venefe&ion and emetics occa- 
fionally, and recommends, after the folution has been omitted 
for a week, to repeat it, to prevent a relapfe. Annals of Med- 
icine, 1797. 
10. Where arfenic has been given as poifon, it may be dif? 
covered in the contents of the ftomach by the fmell like garlic, 
when a few grains of it are thrown on a red-hot iron. 2. If 
a few grains are placed between two plates of copper, and fub- 
jeCted to a red heat, the copper becomes whitened. 3. Dif- 
folve arfenic in water along with vegetable alkali, add to this a 
folution of blue vitriol in water, and the mixture becomes of a 
fine green, which gradually precipitates, as difcovered by Berg- 
man. 4. Where the quantity is fufficient, fome wheat may be 
fteeped in a folution of it, which given to fparrows or chickens 
will deftroy them. 
VII. 1. Abforption of the matter from venereal ulcers. No 
ulcer can heal, unlefs the abforption from it is as great as the 
depofition in it. The preparations or oxydes of mercury in the 
cure of the venereal difeafe feem to aft by their increafmg the 
abforption of the matter in the ulcers it occafions; and that: 
whether they are taken into the ftomach, or applied on the fkin, 
or on the furface of the ulcers. And this in the fame manner 
as fugar of lead, or other metallic oxydes, promote fo rapidly 
the healing of other ulcers by their external application ; and 
probably when taken internally, as rult of iron given to children 
affected with fcrofulous ulcers contributes to heal them, and fo- 
lutions of lead were once famous in phthifis. 
The matter depofited in large abfeeffes does not occafion hec- 
tic fever, till it has become oxygenated by being expofed to the 
open air, or to the air through a moift membrane ; the fame 
feems to happen to other kinds of matter, which produce fever, 
or which occafion fpreading ulcers, and are thence termed con- 
tagious. See Oafs II 1.3. II. 1. 5. II. 1. 6. 6. This may 
perhaps occur from thefe matters not being generallv abforbed, 
till they become oxygenated ; and that it is the ftimulus of the 
acid thus formed by their union with oxygen, which occafions 
their abforption into the circulation, and the fever, which they 
then produce. For though collections of matter, and milk, and 
mucus, are fometimes fuddenly abforbed during the aCtion of 
emetics 58 
SORBENTIA. 
Art. IV. 2. 7. 2. 
emetics or in fea-ficknefs, they are probably eliminated from the 
body without entering the circulation; that is, they are taken 
up by the increafed action of one lymphatic branch, and evacu- 
ated by the inverted action of fome other lymphatic branch, and 
thus carried off by ftool or urine. 
2. But as the matter in large abfeefles is in general not ab- 
forbed, till it becomes by fome means expofed to air, there is 
reafon to conclude, that the ftimulus of this new combination 
of the matter with oxygen occafions its abforption ; and that 
hence the abforption of matter in ulcers of all kinds, is ftill more 
powerfully effected by the external application or internal ufe 
of metallic oxydes ; which are alfo acids confifting of the metal 
united with oxygen ; and laftly, becaufe venereal ulcers, and 
thofe of itch, and tinea, will not heal without fome ftimulant 
application ; that is, the fecretion of matter in them continues 
to be greater, than the abforption of it; and the ulcers at the 
fame time continue to enlarge, by the contagion affefling the 
edges of them ; that is, by the ftimulus of the oxygenated mat- 
ter ftimulated the capillary veflels in its vicinity into a&ions 
fimilar to thofe of the ulcer, which produces it. 
This effect of the oxydes of mercury occurs, whether faliva- 
tion attends its ufe or not. Salivation is much forwarded by 
external warmth, when mercury is given to promote this fecre- 
tion ; but as the cure of venereal complaints depends on its ab- 
forbent quality, the at! of falivation is not neceflary or ufeful. 
A quarter of a grain of good corrofive fublimate twice a day 
will feldom fail of curing the moft confirmed pox ; and will as 
feldom falivate, if the patient be kept cool. A quarter of a 
grain thrice a day I believe to be infallible, if it be good fub- 
limate. 
Mercury alone when fwallowed does not a6t beyond the in- 
teftines ; its active preparations are the faits formed by its union 
with the various acids, as mentioned in the catalogue. Its union 
with the vegetable acid, when triturated with manna, is faid to 
compole Keyfer's Pill. Triturated with gum arabic it is much 
recommended by Plenck ; and triturated with fugar and a little 
effential oil, as directed in a former Edinburgh Difpenfatory, it 
probably forms fome of the fyrups fold as noftrums. 
United with fulphur it feldom enters the circulation, as when 
cinnabar, or aethiops mineral, is taken inwardly. But united 
with fat and rubbed on the Ikin, it is readily abforbed. I know 
not whether it can be united to charcoal, nor whether it has 
been given internally when united with animal fat; if fix grains 
only of fulphur be added to two ounces of hog's fat and fix 
drachms Art. IV. 2. 8. i. 
SORBENTtA. 
59 
drachms of mercury, they are faid to unite with much lefs la- 
bour of trituration, than the hog's fat and mercury alone. 
VIII. i. Abforptions in general are increafed by inanition; 
hence the ufe of evacuations in the cure of ulcers. Dr. Jurin 
abforbed in one night, after a day's abftinence and exercife, 
eighteen ounces from the atmofphere in his chamber ; and eve- 
ry one mull have obferved, how foon his fheets became dry, 
after having been moiftened by fweat, if he throws off part of 
the bed-clothes to cool himfelf; which is owing to the increafed 
cutaneous abforption after the evacuation by previous fweat. 
2. Now as opium is an univerfal ftimulant, as explained in 
the article of Incitantia, it muft ftimulate into increafed adlion 
both the fecretory fyltem, and the abforbent one ; but after re- 
peated evacuation by venefedlion, and cathartics, the abforbent 
fyftem is already inclined to a <51 more powerfully ; as the blood- 
veflels being lefs dillended, there is lefs relillance to the progrefs 
of the abforbed fluids into them. Hence after evacuations opi- 
um promotes abforption, if given in fmall dofes, much more 
than it promotes fecretion ; and is thus eminently of fervice at 
the end of inflammations, as in pleurify, or peripneumony, in 
the dofe of four or five drops of the tindlure, given before the 
accefs of the evening paroxyfm ; which I have feen fucceed 
even when the rifus fardonicus has exilted. Some convulfions 
may originate in the want of the abforption of fome acrid fecre- 
tion, which occafions pain ; hence thefe difeafes are fo much 
more certainly relieved by opium after venefecSlion or other 
evacuations. 
IX. i. Abforption is increafed by the calces or folutions of 
mercury, lead, zinc, copper, iron, externally applied ; and by 
arfenic, and by fulphur, and by the application of bitter vegeta- 
bles in fine powder. Thus an ointment confilling of mercury 
and hog's fat rubbed on the [kin cures venereal ulcers; and ma- 
ny kinds of herpetic eruptions are removed by an ointment con- 
filling of fixty grains of white precipitate of mercury and an 
ounce of hog's fat. 
2. The tumours about the necks of young people are often 
produced by the abforption of a faline or acrid material, which 
has been depofitefl from eruptions behind the ears, owing to de- 
ficient abforption in the furface of the ulcer, but which on run- 
ning down on the fkin below becomes abforbed, and fwells the 
lymphatic glands of the neck ; as the variolous matter, when 
inferted into the arm, fwells the gland of the axilla. Some- 
times the perfpirative matter produced behind the ears becomes 
putrid from the want of daily walhing them, and may alfo caufe 
by its abforption the tumours of the lymphatics of the neck. 
In 60 
S0RBENT1A. 
Art. IV. 2. 9. 3. 
In the former cafe the application of a cerate of lapis calamina- 
ris, or of cerufla in dry powder, or of rags dipped in a folution 
of fugar of lead, increafes the abforption in the ulcers, and pre-i 
vents the effufion of the faline part of the fecreted material. 
The latter is to be prevented by cleanlinefs. 
After the eruptions or ulcers are healed a folution of corrofive 
fublimate of one grain to an ounce of water applied for feme 
weeks behind the ear, and amongft the roots of the hair on one 
fide of the head, where the mouths of the lymphatics of the 
neck open themfelves, frequently removes thefe tumours. 
3. Linen rags moiftened with a folution of half an ounce of 
fugar of lead to a pint of water applied on the eryfipelas on ana- 
farcous legs, which have a tendency to mortification, is more 
efficacious than other applications. White vitriol fix grains 
diffolved in one ounce of rofe water removes inflammations of 
the eyes after evacuation more certainly than folutions of lead. 
Blue vitriol two or three grains diflblved in an ounce of water 
cures ulcers in the mouth, and other mucous membranes, and 
a folution of arfenic externally applied cures the itch, but re- 
quires great caution in the ufe of it. See Oafs II. 1. 5. 6. 
A feeble old man with fwelled legs had an eryfipelas on both 
of them ; to one of thefe legs a fine powder of Peruvian bark 
was applied dry, and renewed twice a day ; on the other linen 
rags moiftened with a folution of faccharum faturni were appli- 
ed, and renewed twice a day ; and it was obferved, that the 
latter healed much fooner than the former. 
As the external application of calx of lead Simulates inflam- 
ed parts very violently, if it be applied too early, before the 
vefl'els are emptied by evacuations, or by the continuance of the 
difeafe, it is liable to increafe the inflammation, or to induce 
mortification, as in ophthalmy ; and in a cafe, which was re- 
lated to me of a perfon who much pricked his legs amongft 
gorfe, which, on the application of Goulard's folution of lead, 
mortified with extenfive Roughs. But where the fyftem is pre- 
vioufly emptied, there is lefs refiftance to the progrefs of ab- 
forbed fluids ; and the Rim ulus of lead then increafes the ac- 
tion of the abforbent fyftem more than of the fecerning fyftem, 
4 id the inflamed part prefently difappears. 
4. Bitter vegetables, as the Peruvian bark, quilted between 
two Hurts, or ftrewed in their beds, will cure the ague in chil- 
dren fometimes. Iron in folution, and fome bitter extract, as in 
the form of ink, will cure one kind of herpes called the ringworm. 
And I have feen feven parts of bark in fine powder mixed with 
one part of cerufe, or white lead, in fine powder, applied dry to 
fcrofulous ulcers, and renewed daily, With great advantage. 
q. Ts Art. IV. 2.9.5. 
SORBENTIA. 
61 
5. To thefe fhould be added elefiric fparks and fliocks, 
which promote the abforption of the vefl'cls in inflamed eyes of 
fcrofulous children; and difperfe, or bring to fuppuration, fcrof- 
ulous tumours about the neck. For this laft purpofe fmart 
fhocks fhould be pafled through the tumours only, by enclofing 
them between two brafs knobs communicating with the external 
and internal coating of a charged phial. See Art. IL 2. 2. 2. 
X. 1. Bandages increafe abforption, if they are made to fit 
nicely on the part; for which purpofe it is neceflary to fpread 
fome moderately adhefive plafter on the bandage, and to cut it 
into tails, or into (breads two inches wide ; the ends are to be 
wrapped over each other ; and it muft be applied when the part 
is leaft tumid, as in the morning before the patient rifes, if on 
the lower extremities. The emplaftrum de minio made to cov- 
er the whole of a fwelled leg in this manner, whether the fwell- 
ing is hard, which is ufually termed fcorbutic ; or more eafily 
compreffible, as in anafarca, reduces the limb in two or three 
days to its natural fize; for this purpofe I have fometimes ufed 
carpenter's glue, mixed with one twentieth part of honey to 
prevent its becoming too hard, inftead of a refinous plafter ; but 
the minium plafter of the fhops is in general to be preferred. 
Nothing fo much facilitates the cure of ulcers in the legs, as 
covering the whole limb from the toes to the knee with fuch a 
plafter bandage ; which increafes the power of abforption in the 
furface of the fore. 
2. The lymph is carried along the abforbent veflels, which arg 
replete with valves, by the intermitted preflure of the arteries in 
their neighbourhood. Now if the external fkin of the limb be lax, 
it rifes, and gives way to the preflure of the arteries at every pul fa* 
tion ; and thence the lymphatic veflels are fubject to the preffure 
of but half the arterial force. But when the external fkin is 
tightened by the furrounding bandage, and thence is not elevated 
by the arterial diaftole, the whole of this power is exerted in 
comprelhng the lymphatic veflels, and carrying on the lymph al- 
ready abforbed ; and thence the abforbent power is fo amazing- 
ly increafed by bandage nicely applied. Pains are fometimes 
left in the flefhy parts of the thighs or arms, after the inflamma- 
tion is gone, in the acute rheumatifm, or after the patient is too 
weak for further evacuation ; in this cafe after internal abforbent 
medicines, as the bark, and opiates, have been ufed in vain, I 
have fuccefsfully applied a plafter-bandage, as above defcribed, 
fo as to comprefs the pained part. 
Since the above was written, Mr. Baynton, an ingenious fur- 
geon of Briftol, has publifhed " A Method of Treating Ulcers 
vf the Legs," fold by Robinfon, Loudon. In which he endeav- 
ouM 62 
SORBENTIA. 
Art. IV. 2. 11. n 
ours to bring the lips of thofe ulcers nearer together by means 
of flips of adhefive platter, as above defcribed; which teems to 
have been attended with great fuccefs, without confinement of 
the patient. See Se<St. XXXIII. 3. 2. 
But when flips of adhefive plafter are put over a wound fo as 
to bring the edges of it together nearly, or quite, into contact 
with each other, the part is at the fame time covered, as the flips 
of adhefive plafter are applied, from the eye of the furgeon. I 
have therefore advifed two tin plates a little longer than the 
wound, and about half an inch broad, to be faftened to the ends 
of the pieces of adhefive plafter, and applied one on each lip of 
the wound or ulcer ; and then by a narrow flip of adhefive plaf- 
ter applied at each end of thefe tins, they maybe drawn togeth- 
er, and the whole lips of the wound may be feen at the fame 
time by the furgeon ; and then a comprefsof thin lead, or of lin- 
en, may be applied by other ftrips of plafter fo as to heal recent 
wounds, and even ulcers, without fcarcely any unevennefs or 
width of the fear. 
XI. 1. We (hall conclude by obferving, that the forbentia 
ftrengthen the whole habit by preventing the efcape of the fluid 
part of the fecretions out of the body, before it has given up as 
much nourifhmeut, as it is capable ; as the liquid part of the fe- 
cretion of urine, fweat, faliva, and of all other fecretions, which 
are poured into receptacles. Hence they have been laid to 
brace the body, and been called tonics, which are mechanical 
terms not applicable to the living bodies of animals; as explain- 
ed in Scot. XXXII. 3. 2. 
2. A continued ufe of bitter medicines for years together, as 
of Portland's powder, or of the bark, is fuppoled to induce apo- 
plexy, or other fatal difeafes. Two cafes of this kind have fall- 
en under my obfervation; the patients were both rather intem- 
perate in refpeft to the ufe of fermented liquors, and one of 
them had been previoufly fubject to the gout. Asi believe the 
gout generally originates from a topor of the liver, which, in- 
ftead of being fucceeded by an inflammation of it, is fucceeded 
by an inflammation of fome of the joints ; or by a pimpled face, 
which is another mode, by which the difeafe of the liver is ter- 
minated : I conceive, that the daily ufe of bitter medicines had 
in thefe patients prevented the removal of a gouty inflammation 
from the liver to the membranes of the joints of the extremities, 
or to the ficin of the face, by preventing the neceflary torpor 
of thefe parts previous to the inflammation of them ; in the fame 
manner as cold fits of fever are prevented by the fame medicines ; 
and, as I believe, the returns of the gout have fome times for 
two or three years been prevented by them; 
One Art. iV. 3. i. 
SORBENTIA, 
63 
One of thefe patients died of the apoplexy in a few hours ; 
and the other of an inflammation of the liver, which 1 believe 
was called the gout, and in confequence was rot treated by ven- 
efeftion, and other evacuations. Hence it appears, that the 
daily ufe of hop in our malt liquor mult add to the noxious qual- 
ity of the fpirit in it, when taken to excefs, and contribute to 
the production of apoplexy, or inflammation of the liver. 
III. Catalogue of the SorbentIa. 
I. SorbentIa affecting the (kin. 
I. Acid of vitriol, of fea-falt, lemons, floes, primus fpL 
nofa, crabs, pyrus, quince, pyrus cydonia, opium. 
2. Externally calx of zinc, of lead, or of mercury. 
11. Sorbentia affecting the mucous membranes. 
i. Juice of floes, crabs, Peruvian bark, cinchona, opium. 
2. Externally blue vitriol. 
HI- Sorbentia affecting the cellular membrane. 
i. Peruvian bark, wormwoods, artemifia maritima, arte-' 
mifia abfynthium, worm-feed, artemifia fantonicumi 
chamomile, anthemis nobilis, tanfey, tanacetum, bog- 
bean, menyanthes trifoliata, centaury, gentiana centau- 
rium, gentian, gentiana lutea, artichoke-leaves, cynara 
fcolymus, hop, humulus lupulus, falix caprea, geum 
urbanum, datifea cannabina. 
2. Orange-peel, cinnamon, nutmeg, mace, 
3. Vomits, fquill, digitalis, tobacco. 
4. Bath of warm air, of fteam. 
1V. Sorbentia affefting the veins. 
1. Water-crefs, fifymbrium nafturtium aquaticuiii, muL 
tard, finapis, feurvy-grafs, cochlearia hortenfis, boric - 
radifli, cochlearia armoracia, cuckoo-flower, carda- 
mine, dog's-grafs, dandelion, leontodon, taraxacon, 
cellery, apium, cabbage, braffica. 
2. Chalybeates, bitters, and opium, after fufficient evac- 
uation. 
3. Externally vinegar, friction, electricity. 
V. Sorbentia affecting the inteftines. 
1. Rhubarb, rheum palmatum, oak-galls, galls quetcinse, 
tormentilia ereCta, cinquefoil, potentilla, red-rofes, 
uva urfi, fimarouba. 
2. Logwood, hsematoxylum, campechianum, fuccus 
acacise, dragon's blood, terra japonica, mimofa catechu, 
3. Alum, earth of alum, Armenian bole, chalk, creta, crab's 
Vol, L IT u u claws, 64 
SORBENTIA. 
Art. IV. 3. 6 
claws, cheke cancrorum, white clay, cimolia, calcined 
hartfhorn, cornu cervi calcinatum, bone-aflies. 
VI. Sorbentia affecting the liver, ftomach, and other vifcera. 
Ruit of iron, filings of iron, fait of fteel, fal martis, 
blue vitriol, white vitriol, calomel, emetic tartar, fugar 
of lead, white arfenic. 
VII. Sorbentia affecting venereal ulcers. Mercury diflblved 
or corroded by the following acids : 
i. Diflblved in vitriolic acid, called turpeth mineral, or 
hydrargyrus vitriolatus. 
2. Diflblved in nitrous acid, called hydrargyrus nitratus 
ruber. 
3. Diflblved in muriatic acid, mercurius corrofivus fub- 
limatus, or hydrargyrus muriatus. 
4. Corroded by muriatic acid. Calomel. 
5. Precipitated from muriatic acid, mercurius precipita- 
tus albus, calx hydrargyri alba. 
6. Corroded by carbonic acid ? The black powder on 
crude mercury. 
7. Calcined, or united with oxygen. 
8. United with animal fat, mercurial ointment. 
9. United with fulphur. Cinnabar. 
1 o. Partially united with fulphur. 2Ethiops mineral. 
11. Divided by calcareous earth. Hydrargyrus cum creta. 
12. Divided by vegetable mucilage, by fugar, by balfams. 
VIII. Sorbentia affecting the whole fyftem. Evacuations 
by venefeftion and catharfis, and then the exhibition 
of opium. 
IX. Sorbentia externally applied. 
1. Solutions of mercury, lead, zinc, copper, iron, arfen- 
ic ; or metallic calces applied in dry powder, as ce- 
rufla, lapis calaminaris. 
2. Bitter vegetables in deco&ions and in dry powders, 
applied externally, as Peruvian bark, oak bark, leaves 
of wormwood, of tanfey, chamomile flowers or leaves. 
3. Eleblric fparks, or Ihocks. 
X. Bandage fpread with emplaftrum e minio, or with car- 
penter's glue mixed with one twentieth part of honey. 
XL Portland's powder its continued ufe pernicious, and of 
hops in beer. 
Art. Art. V. 1. 1. 
INVERTENTIA. 
65 
Art. V. 
INVERTENTIA. 
I. Those things, which invert the natural order of the fuc- 
ceflive irritative motions, are termed invertentia. 
1. Emetics invert the motions of the llomach, duodenum, 
and oefophagus. 
2. Violent cathartics invert the motions of the laCleals, and 
inteflinal lymphatics. 
3. Violent errhines invert the nafal lymphatics, and thofe of 
the frontal and maxillary finufes. And medicines producing 
naufea, invert the motions of the lymphatics about the fauces. 
4. Medicines producing much pale urine, as a certain quan- 
tity of alcohol, invert the motions of the urinary abforbents ; if 
the dofe of alcohol is greater, it inverts the ftomach, producing 
the drunken ficknefs. 
5. Medicines producing cold fweats, palpitation of the 
heart, globus hyftericus ; as violent evacuations, fome poifons, 
fear, anxiety, act by inverting the natural order of the vaicular 
motions. 
IL Observations on the Invertentia. 
I. I. The action of vomiting feems originally to have been 
occafioned by difagreeable fenfation from the diftention or acri- 
mony of the aliment; in the fame manner as when any difguft- 
ful material is taken into the mouth, as a bitter drug, and is re- 
jected by the retrograde motions of the tongue and lips ; as 
explained in Clafs IV. i. I. 2. and mentioned in SeCt. XXXV. 
1.3. Or the difagreeable fenfation may thus excite the power 
of volition, which may alfo contribute to the retrograde actions 
of the itomach and oefophagus, as when cows bring up the con- 
tents of their Hrit Itomach to remafticate it. To either of thefe 
is to be attributed the aCtion of mild-emetics, which foon ceafe 
to operate, and leave the Itomach itronger, or more initable, 
after their operation; owing to the accumulation of the fenfo- 
rial power of irritation during its torpid or inverted aCtion. 
Such appears to be the operation of ipecacuanha, or of antimo- 
nium tartarizatum, in fmall dofes. 
2. But there is reafon to believe, that the Itronger emetics, 
as digitalis, firft ftimulate the abforbent veflels of the Itomach 
into greater aCtion; and that the inverted motions of thefe ab- 
forbents next occur, pouring the lymph, lately taken up, or ob- 
tained 66 
INVERTENTIA. 
Art. V. 2. 1. 2. 
tained from other lymphatic branches, into the ftomach; the 
quantity of which in fome difeafes, as in the cholera morbus, is 
inconceivable. '['his inverted motion, firfl of the abforbents of 
the ftomach, and afterwards of the ftomach itfelf, feems to origi- 
nate from the exhauftion or debility, which fucceeds the un- 
natural degree of a<Slion, into which they had been previoufly 
ftimulated. An unufual defeat of ftimulus, as of food without 
(pice or wine in the ftomachs of thofe, who have been much 
accuftomed to fpice or wine, will induce ficknefs or vomiting ; 
in this cafe the defective energy of the ftomach is owing to. 
deleft of accuftomed ftimulus j white the action of vomiting 
from digitalis is owing to a deficiency of fenforial power, which 
is previoufly exhaufted by the excefs of its ftimulus. See Sefb 
XXXV. i. 3. and Clafs IV. 1.1.2. 
For firft, no increafe of heat arifes from this aflion of vomit- 
ing ; which always occurs, when the fecerning fyftem is ftimu- 
Uted into aftion. Secondly, the motions of the abforbent vef- 
fels are as liable to inverfion as the ftomach itfelf; which laft, 
with the oefophagus, may be confidered as the abforbent mouth 
and belly of that great gland, the inteftinal canal. Thirdly, 
the clafs of' forbentia, as bitters and metallic faits, given in large 
dofes, become invertentia, and vomit, or purge. And laftly, 
the ficknefs and vomiting induced by large potations of wine, 
or opium, does not occur till next day in fome people, in none 
till fome time after their ingurgitation. And tinflure of digi- 
talis in the dofe of 30 or 60 drops, though applied in folution, is 
a confiderable time before it produces its effect', though vomiting 
is inftantaneoufly induced by a nafeous idea, or a naufeous taftt; 
in the mouth. At the fame time there feem to be fome mate- 
rials which can immediaely ftimulate the ftomach into fuch pow- 
erful action, as to be immediately fucceeded by paralyfis of it, 
and confequent continued fever, or immediate death ; and thia 
without exciting fenfation, that is, without our perceiving it. 
Of thefe are the contagious matter of fome fevers fwallowed 
with the faliva, and probably a few grains of arfenic taken in fo- 
lution. Sec Suppl. I. 8. 8. Art. IV. 2. 6. 
3. Some branches of the lymphatic fyftem become inverted 
by their fympathy with other branches, which are only ftimu- 
lated into too violent abforption. Thus, when the ftomach and 
duodenum are much ftimulated by alcohol, by nitre, or by 
worms, in fome perfons the urinary lymphatics have their mo- 
tion inverted, and pour that material into the bjadder, which is 
abforbed from the inteftines. Hence the drunken diabetes 
is produced ; and hence chyle is feen in the urine in worm 
vafes.. 
Whcu Art. V?2. 1.4. 
INVERTENTIA. 
67 
When on the contrary feme branches of the abforbent fyftems 
have their motions inverted in confequence of the previous ex- 
hauftion of their fenforial power by any violent Itimulus, other 
branches of it have then* abforbent power greatly increafed. 
Hence continued vomiting, or violent cathartics, produce great 
abforption from the cellular membrane in cafes of dropfy; and 
the fluids thus abforbed are poured into the ftomach and intef- 
tines by the inverted motions of the la&eals and lymphatics. See 
Sed. XXIX. 4. and 5. 
4. The quantity of the dofe of an emetic is not of fo great 
confequence as of other medicines, as the greateft part of it is 
rejected with the firft effort. All emetics are faid to aa with 
greater certainty when given in a morning, if an opiate had 
been given the night before. For the fenforial power of irrita- 
tion of the ftomach had thus been in fame meafure previoufly 
exhaufled by the Itimulus of the opium, which thus facilitates 
the aaion of the emetic; and which, when the dofe of opium 
has been large, is frequently followed on the next day by Spon- 
taneous fleknefs and vomitings, as after violent intoxication. 
Ipecacuanha is the moil certain in its effect from five grains 
to thirty; white vitriol is the moft expeditious in its effect, 
from twenty grains to thirty diflblved in warm water ; but emet- 
ic tartar, antimonium tartari?atum, from one grain to four to 
fane people, and from thence to twenty to infane patients, will 
anfwer mofl of the ufeful purpofes of emetics; but nothing 
equals the digitalis purpurea for the purpofe of abforbing water 
from the cellular membrane in the anafarca pulmonum, or hy- 
drops pedloris, See Art, II. 3. 7. 
IL Violent cathartics. 1, Where violent cathartics are re- 
quired, as in dropfies, the fquill in dried powder made into 
fmall pills of a grain, or a grain and a half, one to be given ev- 
ery hour till they operate brifkly, is very efficacious; or half a 
grain of emetic tartar diflolved in an ounce of peppermint-water, 
and given every hour, till it operates. Scammony, and other 
ftrong purges, are liable to produce hypercatharfis, if they are 
not nicely prepared, and accurately weighed, and are thence 
dangerous in common practice. Gamboge is uncertain in its 
effects, it has otherwife the good property of being taftelefs ; and 
on that account fome preparation of it might be ufeful for chil- 
dren, by which its dofe could be afeertained, and its eflects ren- 
dered more uniform. 
2- In inflammations of the bowels with conftipatlon calomel, 
given in a dofe from ten to twenty grains after due venefetlion, 
is molt eflicacious; and if made into very fmall pills is not lia- 
bk to be rejected by vomiting, which generally attends thole 68 
INVERTENTIA. 
Art. V. 2. 3. u 
cafes. When this fails, a grain of aloes every hour will find its 
way, if the bowel is not deftroyed ; and fometimes, I believe, if 
it be, when the mortification is not extenfive. If the vomiting 
continues after the pain ceafes, and efpecially if the bowels be- 
come tumid with air, which founds on being ftruck with the 
finger, thefe patients feldom recover. Opiates given along 
with the cathartics I believe to be frequently injurious in inflam- 
mation of the bowels, though they may thus be given with ad- 
vantage in the faturnine colic; the pain and conftipation in 
which difeafe are owing to torpor or inactivity, and not to too 
great aClion. See Clafs I. 2. 4. 8. 
III. Violent errhines and fialagogues. 1. Turpeth mineral 
in the quantity of one grain mixed with ten grains of fugar an- 
fwers every purpofe to be expeCted from errhines. Their oper- 
ation is by inverting the motions of the lymphatics of the mem- 
brane, which lines the noftrils, and the caverns of the forehead 
and cheeks ; and may thence pofllbly be of fervice in the hydro- 
cephalus internus. 
Some other violent errhines, as the powder of white hellebore, 
or Cayenne pepper, diluted with fome lefs acrid powder, are faid 
to cure fome cold or nervous head-achs ; which may be effect- 
ed by inflaming the noftrils, and thus introducing the fenforial 
power of fenfation, as well as increafing that of irritation ; and 
thus to produce violent aCtion of the membranes of the noftrils, 
and of the frontal and maxillary finufes, which may by affocia- 
tion excite into aCtion the torpid membranes, which occafion the 
head-ach. They may be ufed on the fame account in amauro- 
fis and in deafnefs. 
2. A copious falivation without any increafe of heat often at- 
tends hyfteric difeafes, and fevers with debility, owing to an in- 
verfion of the lymphatics of the mouth, fee Clafs I. 1. 2. 6. The 
fame occurs in the naufea, which precedes vomiting ; and is alfo 
excitable by difagreeable taftes, as by fquills, or by naufeous 
frnells, or by naufeous ideas. Thefe are very flmilar to the oc- 
cafional difeharge of a thin fluid from the noftrils of fome peo- 
ple, which recurs at certain periods, and differs from defective 
abforption. 
IV. Violent diuretics. 1. If nitre be given frem a dram to 
half an ounce in a morning at repeated draughts, the patient 
becomes fickifti, and much pale water is thrown into the blad- 
der by the inverted action of the urinary lymphatics. Hence the 
abforption in ulcers is increafed and the cure forwarded, as ob- 
ferved by Dr. Rowley. 
2. Cantharides taken inwardly fo ftimulate the neck of the 
bladder as to increafe the difeharge of mucus, which appears in 
the Art. V. 2.4.3. 
INVERTENTIA. 
69 
the urine j but I once faw a large dofe taken by miftake, not lefi 
than half an ounce or an ounce of the tinfture, by which I fup- 
pofe the urinary lymphatics were thrown into violent inverted 
motions, for the patient drank repeated draughts of fubtepid 
water to the quantity of a gallon or two in a few hours; and 
during the greatelt part of that time he was not I believe two 
entire minutes together without making water. A little blood 
was feen in his water the next day, and a forenefs continued a 
day longer without any other inconvenience. 
3. The decodlion of foxglove fhould alfo be mentioned here, 
as great effufions of urine frequently follow its exhibition. See 
Art. IV. 2. 3. 7. And an infufion or tincture of tobacco as 
recommended by Dr. Fowler of York. 
4. Alcohol, and opium, if taken fo as to induce flight intoxi- 
ication, and the body be kept cool, and much diluting liquids 
taken along with them, have flmilar effect in producing for a 
time a greater flow of urine, as moft intemperate drinkers muft 
occafionally have obferved. This circumftance feems to have 
introduced the ufe of gin, and other vinous fpirits, as a diuretic, 
unfortunately in the gravel, amongft ignorant people ; which 
difeafe is generally produced by fermented or fpirituous liquors, 
and always increafed by them. 
5. Fear and anxiety are well known to produce a great fre- 
quency of making water. A perfon who believed he had made 
a bad purchafe concerning an eftate, told me, that he made five 
or fix pints of water during a fleeplefs night, which fucceeded 
his bargain ; and it is ufual, where young men are waiting in 
an antiroom to be examined for college preferment, to fee the 
chamber-pot often wanted. 
V. Cold fweats about the head, neck, and arms, frequently 
attend thofe, whofe lungs are opprefled, as in fome dropfies and 
afthnia. A cold fweat is alfo frequently the harbinger of death* 
Thefe are from the inverted motions of the cutaneous lymphat-* 
ic branches of thofe parts. 
III. Catalogue of Invertentia. 
I. Emetics, ipecacuanha, emetic tartar, antimonium tartan- 
fatum, fquill, fcilla maritima, carduus benedidtus, cni- 
cus acarna, chamomile, anthemis nobilis, white vitriol, 
vitriolum zinci, foxglove, digitalis purpurea, clyfters 
of tobacco. 
II. Violent cathartics, emetic tartar, fquill, buckthorn, rham- 
nus catharticus, fcammonium, convolvulus fcammo- 
nia. 70 
REVERTENTIA. 
Art. VI. t. n 
nia, gamboge, elaterium, colocynth, cucumis colocyn- 
this, veratrum. 
III. Violent errhines and fialagogues, turpeth mineral, hydra* 
gvrus vitriolatus, afarum europaeum, euphorbium, cap- 
Gcum, veratrum, naufeous fmells, naufeous ideas. 
IV. Violent diuretics, nitre, fquill, feneka, cantharides, alco- 
hol, foxglove, tobacco, anxiety. 
V. Cold fudorifics, poifons, fear, approaching death. 
Art. VI. 
REVERTEbTHA. 
L Those things, which reftore the natural order of the in- 
verted irritative motions, are termed Revertentia. 
i. As mufk, caftor, afafoctida, valerian, eflential oils. 
2. Externally the vapour cf burnt feathers, of volatile faits, 
Or oils, blifters, fmapifins. 
Thefe reclaim the inverted motions without increafing the 
heat of the body above its natural ftate, if given in their proper 
dofes, as in the globus hyftericus, and palpitation of the heart, 
The incitantia revert thefe morbid motions more certainly, as 
opium and alcohol: and reftore the natural heat more ; but if 
they induce any degree of intoxication, they are lucceeded by 
debility, when their ftimulus ceafes. 
II. Observations on the Revertentia. 
I. i. The hyfteric difeafe is attended with inverted motions 
feebly exerted of the oefophagus, inteftinal canal and lymphat- 
ics of thebladder. Hence the borborigmi,or rumbling of the bow- 
els, owing to their fluid contents defcending as the air beneath 
alcends. The globus hyftericus confifts in the retrograde mo- 
tion of the oefophagus, and the great flow of urine from that of 
the lymphatics fpread on the neck of the bladder ; and a copious 
falivation fometimes happens to thefe patients from the inverfiort 
of the lymphatics of the mouth ; and palpitation of the heart 
owing to weak or incipient inverfion of its motions ; and fiyn- 
cope, when this occurs in its greateft degree. 
Thefe hyfteric affections are not necefl'arily attended with 
pain ; though it fometimes happens, that pains, which originate 
• from Art. V. 2. 2. i. 
REVERTENTIA. 
71 
from quiefcence, afflicl thefe patients, as the hemicrania, which 
has erroneoufly been termed the clavus hyftericus ; but which is 
owing folely to the inaction of the membranes of that part, like 
the pains attending the cold fits of intermittents, and which fre- 
quently returns like them at very regular periods of time. 
Many of the above fymptoms are'relieved by mufle, caftor, 
the foetid gums, valerian, oleum animale, oil of amber, which 
act in the ufual dofe without heating the body. The pains, 
which fometimes attend thefe conftitutions, are relieved by the 
fecernentia, as eflential oils in common tooth-ach, and balfam of 
Peru, in the flatulent colic. But the incitantia, as opium, or 
vinous fpirit, reclaim thefe morbid inverted motions with more 
certainty than the foetids; and remove the pains which attend 
thefe conftitutions, with more certainty than the fecernentia ; 
but if given in large dofes, a debility and return of the hyfteric 
fymptoms occurs, when theeffeft of the opium or alcohol ceafes. 
Opiates and foetids joined feem beft to anfwer the purpofe of 
alleviating the prefent fymptoms; and the forbentia, by ftimu- 
lating the lymphatics and ladteals into continued adlion, prevent 
a relapfe of their inverfion, as Peruvian bark, and the ruft of 
iron. See Clafs I. 3. 1. 10. 
II. Vomiting confifts in the inverted order of th^motions 
of the ftomach, and cefophagus ; and is alfo attended with the 
inverted motions of a part of the duodenum, when bile is eject- 
ed ; and of the lymphatics of the ftomach and fauces, when 
naufea attends, and when much lymph is evacuated. Perma- 
nent vomiting is for a time relieved by the incitantia, as opium 
or alcohol; but is liable to return when their action ceafes. A 
blifter on the back, or on the ftomach, is more efficacious for re- 
ftraining vomiting by their ftimulating into action the external 
Ikin, and by fympathy affefting the membranes of the ftomach. 
In fome fevers attended with inceflant vomiting Sydenham ad- 
vifed the patient to put his head under the bed-clothes, till a 
fweat appeared on the fkin, as explained in Clafs IV. 1. 1. 3. 
In chronical vomiting I have obferved crude mercury of good 
effect in the dofc of half an ounce twice a day. The vomitings, 
or vain efforts to vomit, which fometimes attend hyfteric or ep- 
ileptic patients, are frequently inftantly relieved for a time by 
applying flour of muftard-feed and water to the fmall of the 
leg ; and removing it, as foon as the pain becomes confiderable. 
If finapifms lie on too long, efpecially in paralytic cafes, they are 
liable to produce troublefome ulcers. A plafter or cataplafm, 
with opium and camphor on the region of the ftomach, will 
fometimes revert its retrogade motions. 
III. Violent catharfis, as in diarrhoea or dyfentery, is attend- 
VoL. I. W w w ed 72 
REVERTENTIA. 
Art. VI. 2.4. 
ed with inverted motions of the lymphatics of the inteftines, and 
is generally owing to fome ftimulating material. This is coun- 
teracted by plenty of mucilaginous liquids, as folutions of gum 
arabic, or fmall chicken broth, to wafh away or dilute the ftim- 
ulating material, which caufes the difeafe. And then by the ufe 
of the inteftinal forbentia, Art. IV. 2. 5. as rhubarb, decoftion 
of logwood, calcined hartfhorn, Armenian bole; and laftly, by 
the incitantia, as opium. 
IV. The diaboetes confifts in the inverted motions of the 
urinary lymphatics, which is generally I fuppofe owing to the 
too great action of fome other branch of the abforbent fyftem. 
The urinary branch fhould be ftimulated by cantharides, turpen- 
tine, refin, (which when taken in larger dofes may poflibly excite 
, it into inverted adftion), by the forbentia and opium. The intef- 
tinal lymphatics fhould be rendered lefs a<ftive by torpentia, 
as calcareous earth, earth of alum ; and thofe of the fkin by 
oil externally applied over the whole body ; and by the warm- 
bath, which fhould be of ninety-fix or ninety-eight degrees of 
heat, and the patient fhould fit in it every day for half an hour. 
V. Inverted motions of the inteftinal canal with all the lymph- 
atics, which open into it, conftitute the ileus, or iliac paffion ; 
in whicl^ifeafe it fometimes happens, that clyfters are returned 
by the mouth. After venefeftion from ten grains to twenty of 
calomel made into very fmall pills ; if thefe be rejected, a grain 
of aloe every hour ; a blifter, crude mercury; warm-bath; if a 
clyfter of it^d water ? 
Many other inverted motions of different parts of the fyftem 
are defcribed in Clafs I. 3. and which are to be treated in a man- 
ner fimilar to thofe above defcribed. It muft be noted, that 
the medicines mentioned under number one in the catalogue of 
revertentia are the true articles belonging to this clafs of medi- 
cines. Thofe enumerated in the other four divifions are chiefly 
fuch things as tend to remove the ftimulating caufes, which 
have induced the inverfion of the motions of the part, as acrimo- 
nious contents, or inflammation, of the bowels in diarrhoea, dia- 
betes or in ileus. But it is probable after thefe remote caufes 
are deftroyed, that the fetid gums, mufk, caftor, and balfams, 
might be given with advantage in all thefe cafes. 
III. Catalogue of Revertentia. 
I. Inverted motions, which attend the hyfteric difeafe, are re- 
claimed, i. By mufk, caftor. 2. By afafoctida, galba- 
num, fagapenum, ammoniacum, valerian. 3. Eflential 
oils of cinnamon, nutmeg, cloves, infufion of penny-roy- 
al. Art. VII. 1.1. 
TORPENTIA. 
73 
al, mentha pulegium, peppermint, mentha piperita, ether, 
camphor. 4. Spirit of hartfhorn, oleum animale, fponge 
burnt to charcoal, black fnuffs of candles, which confift 
principally of animal charcoal, wood-foot, oil of amber. 
5. The incitantia, as opium, alcohol, vinegar. 6. Ex- 
ternally the fmoke of burnt feathers, oil of amber, vola- 
tile fait applied to the noftrils, blifters, finapifms. 
II. Inverted motions of the ftomach are reclaimed by opium, 
alcohol, blifters, crude mercury, finapifms, camphor and 
opium externally, clyfters with afafoetida. 
III. Inverted motions of the inteftinal lymphatics are reclaim- 
ed by mucilaginous diluents, and by inteftinal forben- 
tia, as rhubarb, logwood, calcined hartfhorn, Armenian 
bote ; and laftly by incitantia, as opium. 
IV. Inverted motions of the urinary lymphatics are reclaim- 
ed by cantharides, turpentine, refin, the forbentia, and 
opium, with calcareous earth of alum, by oil externally, 
warm-bath. 
V. Inverted motions of the inteftinal canal are reclaimed by 
calomel, aloe, crude mercury, blifters, warm-bath, clyl- 
ters with afafoetida, clyfters of iced water ? or of fpring 
water further cooled by fait diflblved in water contained 
in an exterior veflel ? Where there exifts an introful- 
ception of the bowel in children, could the patient be 
held up for a time by the feet with his head downwards, 
or be laid with his body on an inclined plane with his 
head downwards, and crude mercury be injected as a 
clyfler to the quantity of two or three pounds ? 
Art. VII. 
TORPENTIA. 
I. Those things, which diminifh the exertion of the irrita- 
tive motions, are termed torpentia. 
1. As mucus, mucilage, water, bland oils, and whatever 
pofTefTes lefs ftimulus than our ufual food. Diminution of heat, 
light, found, oxygen, and of all other ftimuli; venefeftion, nau- 
fea, and anxiety. 
2. Thofe things which chemically deftroy acrimony, as calca- 
reous earth, foap, tin, alkalies, in cardialgia; or which prevent 
chemical 74 
TORPENTIA. 
Art. VII. 2. i. i. 
chemical acrimony, as acid of vitriol in cardialgia, which pre- 
vents the fermentation of the aliment in the ftomach, and its 
confequent acidity. Secondly, which deftroy worms, as calo- 
mel, iron filings or ruft of iron, in the round worms ; or amal- 
gama of quick fil ver and tin, or tin in very large dofes, in the 
tape-worms. Will ether in clyfters deftroy afcarides ? Thirdly, 
by chemically deftroying extraneous bodies, as cauftic alkali, 
lime, mild alkali in the ftone. Fourthly, thofe things which lu- 
bricate the veflels, along which extraneous bodies flide, as oil in 
the ftone in the urethra, and to expedite the expectoration of 
hardened mucus ; or which leflen the friction of the contents 
in the inteftinal canal in dyfentery or aphtha, as calcined hartf- 
horn, clay, Armenian bole,, chalk, bone-afhes. Fifthly, fuch 
things as foften or extend the cuticle over tumors, or phleg- 
mons, as warm water, poultices, fomentations, or by confining 
the perfpirabie matter on the part by cabbage-leaves, oil, fat, 
bee's-wax, plafters, oiled filk, externally applied. 
Thefe decreafe the natural heat and remove pains occafioned 
by excefs of irritative motions. 
II. Observation^ on the Torpentia. 
I. As the torpentia confift of fuch materials as are lefs ftim- 
ulating than our ufual diet, it is evident, that where this clafs of 
medicines is ufed, fome regard muft be had to the ufual manner 
of living of the patient both in refpedt to quantity and quality. 
Hence wounds in thofe, who have been accuftomed to the ufe 
of much wine, are very liable to mortify, unlefs the ufual pota- 
tion of wine be allowed the patient. And in thefe habits I have 
feen a delirium in a fever cured almoft immediately by wine; 
which was occafioned by the too mild regimen directed by the 
attendants. On the contrary in great inflammation, the fub- 
duction of food, and of fpirituous drink, contributes much to the 
cure of the difeafe. As by thefe means both the ftimulus from 
diftention of the veflels, as well as that from the acrimony of 
the fluids, is decreafed; but in both thefe refpe&s the previous 
habits of diet of the patients muft be attended to. Thus if tea 
be made ftronger, than the patient has ufually drunk it, it be- 
longs to the article forbentia; if weaker, it belongs to the tor- 
pentia. 
IL i. Water in a quantity greater than ufual diminifhes the 
aflion of the fyftem not only by diluting our fluids, and thence 
leflening their ftimulus, but by lubricating the folids ; for not 
only parts of our folids have their Hiding over each other facili- 
tated by the interpofition of aqueous particles j but the particles 
of Art. VII. 2. 3.1. 
TORPENTIA. 
75 
of mucaginous or faccharine folutions Aide eafier over each oth- 
er by being mixed with a greater portion of water, and thence 
ftimulate the veflels lefs. 
At the fame time it muft be obferved, that the particles of 
water themfelves, and of animal gluten diflblved in water, as 
the glue ufed by carpenters, Aide eafier over each other by an 
additional quantity of the Auid matter of heat. 
Thefe two fluids of heat and of water may be efteemed the 
univerfal folvents or lubricants in refpect to animal bodies, and 
thus facilitate the circulation, and the fecretion of the various 
glands. At the fame time it is poffible, that thefe two fluids 
may occafionally aflume an aerial form, as in the cavity of the 
cheft, and by comprefling the lungs may caufe one kind of 
afthma, which is relieved by breathing colder air. An increaf- 
ed quantity of heat by adding ftimulus to every part of the fyf- 
iem belongs to the article Incitantia. 
III. i. The application of cold to tire (kin, which is only 
another exprellion for the diminution of the degree of heat we 
are accuftomed to, benumbs the cutaneous abforbents into inac- 
tion ; and by fympathy the urinary and inteilinal abfoibents be- 
come alfo quiefcent. The fecerning veflels continuing their ac- 
tion fomewhat longer, from the warmth of the blood. Hence 
the ufual fecretions are poured into the bladder and inteftines, 
and no abforption is retaken from them. Hence fprinkling the 
fkin with cold water increafes the quantity of urine, which is 
pale j and of ftool, which is fluid j thefe have erroneoufly been 
afcribed to increafed fecretion, or to obftrutted perfpiration. 
The thin difcharge from the noftrils of fome people in cold 
weather is owing to the torpid fl.ate of the abforbent veflels of 
the membrana fchneideriana, which as above are benumbed 
fooner than thofe, which perform the fecretion of the mucus. 
The quick anhelation, and palpitation of the heart, of thofe, 
who are immcrfed in cold water, depends on the quiefcence of 
the external abforbent veflels and capillaries. Hence the cuta- 
neous circulation is diminifhed, and by aflbciation an almolt 
univerfal torpor of the fyftem is induced ; thence the heart be- 
comes incapable to puflr forwards its blood through all the inac- 
tive capillaries and glands ; and as the terminating veflels of the 
pulmonary artery fuffer a fimilar inaction by aflbciation, the 
blood is with difficulty puffied through the lungs. 
Some have imagined, that a fpafmodic conftrirtion of the 
fmaller veflels took place, and have thus accounted for their re- 
fiftance to the force of the heart. But there feems no neceffity 
to introduce this imaginary fpafm ; fince thofe, who are con- 
verfant in injecting bodies, find it neceflary firft to put them 
int® 76 
TORPENTIA. 
Art. VII. 2. 3. 1. 
into warm water to take away the ftiflhefs of the cold dead vef- 
fels; which become inflexible like the other mufcles of dead 
animals, and prevent the injected fluid from palling. 
Before the improved knowledge of chemiltry, and of natural 
philofophy, and of the laws of organic life, fome writers have 
ipoken of cold as a ftimulus to the fyltem, inftead of fpeaking 
of it as a diminution of the ftimulus of heat. But the immedi- 
ate confequence of ftimulus is the exertion of the ftimulated 
fibres ; now an increafed application of heat is followed by an 
increafed adion of the fibres expofed to it; but an increafed 
application of cold is followed by a decreafed action of the fibres 
expofed to it; as appears by the rednefs of our hands when 
warmed by the fire, and the palenefs of them, when they have 
been a while covered with fnow. 
A painful fenfation fucceeds the defeat as well as the excefs 
of the ftimulus of heat, as mentioned in Vol. I. Se6t. IV. 5. 
and the voluntary exertions of the fubcutaneous mufcles called 
fhuddering, are excited to relieve the pain occafioned by the tor- 
por of the fibres expofed to cold ; and thofe of the mufcles 
fubfervient to refpiration are voluntarily excited in fcreaming to 
relieve the pain occafioned by heat, which may have occafioned 
the error above mentioned. 
Others have fpoken of a fedative quality of cold, which is cer- 
tainly an unphilofophical expreflion 5 as a fedative power, if it 
has any diftinft meaning, fhould exprefs a power of diminifhing 
any unnatural or exceflive motions of the fyftem ; but the ap- 
plication of cold diminifhes the activity of the fibres in general, 
which may previoufly be lefs than natural, as well as greater. 
All the fame fymptoms occur in the cold fits of intermit- 
tents ; in thefe the coldnefs and palenefs of the Ikin with thirft 
evince the diminution of cutaneous abforption; and the drynefs 
of ulcers, and fmall fecretion of urine, evince the torpor of the 
fecerning fyftem ; and the anhelation, and coldnefs of the 
breath, ihew the terminations of the pulmonary artery to be 
like wife'affc&ed with torpor. 
After thefe vefl'els of the whole furface of the body both ab- 
forbent and fecretory have been for a time torpid by the appli- 
cation of cold water ; and all the internal fecerning and abforb- 
ent ones have been made torpid from their aflbeiation with the 
external; as foon as their ufual ftimulus of warmth is renewed, 
they are thrown into more than their ufual energy of aftion ; 
as the hands become hot and painful on approaching the fire 
after having been immerfed fome time in fnow. Hence the 
face becomes of a red colour in a cold day on turning from the 
wind, Art. VII. 2.3.2. 
TORPENTIA* 
77 
wind, and the infenfible peripiration increafed by repeatedly go* 
ing into frofty air, but not continuing in it too long at a time. 
2. When by the too great warmth of a room or of clothes 
the fecretion or perfpirable matter is much increafed, the ftrength 
of the patient is much exhaufted by this unneceflary exertion of 
the capillary fyftem, and thence of the whole fecerning and ar- 
terial fyftem by aflbciation. The diminution of external heat 
immediately induces a torpor or quiefcence of thefe unneceflary 
exertions, and the patient inftantly feels himfelf ftrengthened, 
and exhilarated ; "the animal power, which was thus wafted in 
vain, being now applied to more ufeful purpofes. Thus when 
the limbs on one fide are difabled by a ftroke of the pally, thofe 
of the other fide are perpetually in motion. And hence all 
people bear riding and other exercifes beft in cold weather. 
Patients in fevers, where the Ikin is hot, are immediately 
ftrengthened by cold air ; which is therefore of great ufe in fe- 
vers attended with debility and heat; but may perhaps be of 
temporary diflervice, if too haftily applied in fome fituations of 
fevers attended with internal topical inflammation, as in perip- 
neumony or pleurify, where the arterial ftrength is too great al- 
ready, and the increafed action of the external capillaries being 
deftroyed by the cold, the action of the internal inflamed part 
may be fuddenly increafed, unlefs venefeiiion and other evacu- 
ations are applied at the fame time. Yet in moft cafes the ap- 
plication of cold is neverthelefs falutary, as by decreafing the 
heat of the particles of blood in the cutaneous veflels, the ftim- 
ulus of them, and the diftention of the veflels becomes confider- 
ably leflened. In external inflammations, as the fmall-pox, and 
perhaps the gout and rheumatifm, the application of cold air 
muft be of great fervice by decreafing the action of the inflamed 
(kin, though the contrary is too frequently the practice in thofe 
difeafes. It muft be obferved, that for all thefe purpofes the ap- 
plication of it fliould be continued a long time, otherwife an in- 
creafed exertion follows the temporary torpor, before the djfeafe 
is deftroyed. 
The topical application of cold to relieve inflammatory pains, 
or to deftroy the too great action of the veflels, may be ufed 
with great advantage. In local inflammations, as in the pleuri- 
fy, or ophthalmia, or in local pains from the ftimulus of an ex- 
traneous body, as in gravel defcending along the ureter, the ap- 
plication of cold on or near the affected part may be ufed with 
falutary eflebt, as by prefling on the part a bladder full of cold 
water with fait diflblving in it; or by the evaporation of ether 
on it; which may render the veflels torpid or inactive. But the 
application of cold to the whole fkin might increafe the action 
of 80 
TORPENTIA. 
Art. VII. 2. 5. 
ry haemorrhages, every one juftly applies to it, as the certain and 
only cure. 
V. When the circulation is carried on too violently, as in 
inflammatory fevers, thofe medicines, which invert the motions 
of fome parts of the fyftem, retard the motions of fome other 
parts, which are alTociated with them. Hence fmall dofes of 
emetic tartar, and ipecacuanha, and large dofes of nitre, by pro- 
ducing naufea debilitate and leflen the energy of the circulation, 
and are thence ufeful in inflammatory difeafes. It muft be add- 
ed, that if nitre be fwallowed in powder, or foon after it is dif- 
folved, it contributes to leflen the circulation by the cold it gen- 
erates, like ice-water, or the external application of cold air. 
VI. ,The refpiration of air mixed with a greater proportion 
of azote than is found in the common atmofphere, or of air mix- 
ed with hydrogen, or with carbonic acid gas, fo that the quanti- 
ty of oxygen might be lefs than ufual, would probably aft in 
cafes of inflammation with great advantage. In confumptions 
this might be moft conveniently and effeftually applied, if a 
phthifical patient could refide day and night in a porter or ale 
brewery, where great quantities of thofe liquors were perpetu- 
ally fermenting in vats or open barrels; or in fome great manu- 
faftory of wines from raifins or from fugar. 
Externally the application of carbonic acid gas to cancers 
and other ulcers initead of atmofpheric air may prevent their 
enlargement, by preventing the union of oxygen with the mat- 
ter, and thus producing a new contagious animal acid. 
III. Catalogue of Torpentia. 
i. Venefeftion. Arteriotomy. 
2. Cold water, cold air, refpiration of air with lefs oxygen. 
3. Vegetable mucilages. 
a. Seeds.-Barley, oats, rice, young peas, flax, cucumber, 
melon, &c. 
b. Gums.-Arabic, tragacanth, Senegal, of cherry-trees. 
c. Roots.-Turnip, potatoe, althea, orchis, fnow-drop. 
d. Herbs.-Spinach, brocoli, mercury. 
4. Vegetable acids, lemon, orange, currants, goofeberries, 
apples, grape, &c. 
Animal mucus, hartfhorn jelly, veal broth, chicken water, 
oil ? fat ? cream ? 
6. Mineral acids, of vitriol, nitre, fea-falt. 
7. Silence, darknefs. 
3. Invertentia in fmall dofes, nitre, emetic tartar, ipecacuanha 
given fo as to induce naufea. 
> 9. Antacids. Art. VII. 3. 9. 
TORPENTIA. 
81 
9. Antacids.-Soap, tin, alkalies, earths. 
io. Medicines preventive of fermentation, acid of vitriol. 
11. Anthelmintics.-Indian pink, tin, iron, cowhage, amalga- 
ma, fmoke of tobacco. 
12. Lithontriptics, lixiv. faponarium, aqua calcis, fixable air. 
13. Externally, warm bath, and poultices, oil, fat, wax, plafters, 
oiled filk, carbonic acid gas on cancers, and other ulcers. 
END OF THE THIRD PART. INDEX 
TO THE 
SECTIONS OF PART FIRST. 
jZ^BORTION from fear, xxxix. 6. 5. 
Abforption of folids,xxxiii. 3.1.xxxvii. 
of fluids in anafarca, xxxv. 
x. 3* 
in warm bath, xxix. 4. 5. 
Abforbent veffels, xxii. 2. xxix. 1. 
regurgitate their fluids, 
xxix. 2. 
their valves, xxix. 2. 
communicate with vena 
portarum, xxvii. 2. 
Accumulation of fenforial power, iv. 
2. xii. 5. 2. 
Activity of fyflem. too great, cure of, 
xii. 6. 
too fmall, cure of, xx. 7. 
Age, old, xii. 3. 1. xxxvii. 4. 
Ague-fit, xii. 7. 1. xxxii. 3. 4. xxxii. 9. 
how cured by bark, xii. 3. 4. 
periods, how occafioned xii. 
2. 3. xxxii. 3. 4. xvii. 3. 6. 
Ague cakes, xxxii. 7. xxxii. 9. 
Air, fenfe of frefh, xiv. 8. 
injures ulcers, xxviii. 2. 
injeCted into veins, xxxii. 5. 
Air-cells of the lungs, xxviii. 2. 
Alcohol deleterious, xxx. 3. 
Alliterations, why agreeable, xxii. 2. 
Aloes in leffened dofes, xii. 3.1. 
American natives indolent, xxxi. 2. 
narrow iliouldered, 
xxxi. r. 
Analogy intuitive, xvii. 3. 7. 
Animals lefs liable to madnefs, xxxiii. 1. 
lefs liable to contagion, xxxiii. I. 
how to teach, xxii. 3. 2. 
their fimilarity to each other, 
xxxix. 4. 8. 
their changes after nativity, 
xxxix. 4. 8. 
their changes before nativity, 
xxxix. 4 8. 
Vot. I V v y 
Animals, lefs liable to contagious dix* 
eafes, why, xxxiii. I. 5. 
lefs liable to delirium and in* 
fanity, why, xxxiii. I. 5. 
eafier to preferve than to re* 
produce, xxxvih 
electricity, xiv. 5. 
food, diftafte of, xxxviii. T. 
appetency, xxxix, 4. 7. 
Animalcula, xxxix. 11. J, 
from boiling broth, xxxix. 
11. 1. 
Antipathy, x. 2. 2. 
Appetites, xi. 2. 2. xiv. 8. 
Aphthse, xxviii. 
Apoplexy, xxxiv. 1.7. 
not from deficient irrita- 
tion, xxxii. 2. 1. 
Architecture, xii. 3.3. xvi. io. 
Arts, fine, xxii. 2. 
Afparagus, its fmell in urine, xxix. 
Aflociation defined, ii. t.11. iv. 7. v. 2. 
affociate motions, x. 
ftronger than irritative 
ones, xxiv. 2. 8. 
formed before nativity, 
xi. 3. 
with irritative ones, xxiv. 8. 
with retrograde ones, xxV. 
7. xxv. 10. xxv. 15. 
difeafes from, xxxv. 
Afthma, xviii. 15. 
Attention, language of, xvi. 8. 6. 
Atrophy, xxviii. 
Averfion, origin of, xi. 2. 3. 
B. 
Balance ourfelves by vifion. xx. r. 
Bandage increafes abforption. xxx h 
•3- »* . 
Barrennefs, xxxvi. 2. 3. 
Battement of founds, xx. 7. 
Bath, 84 
INDEX TO THE SECTIONS.-Part I. 
Bath, cold. See Cold Bath. 
Bath, warm, xxix. 4. 5. 
Beauty, fenfe of, xvi 6. xxii. i. 
Bile-dudts, xxx. 
Bones, xxx. 3. 
regurgitates into the blood, xxiv. 
a. 7. 
vomiting of, xxx. 3. 
Birds of paffage, xvi. 12. 
nefts of, xvi. 13. 
colour of their eggs, xxxix. 5. 
Biting in pain, xxxiv. 1. 3. 
of mad animals, xxxiv. 1. 3, 
Black fpots on dice appear red, xl. 3. 
Bladder, communication of with the 
inteffines, xxix. 3, 
of fifh, xxiv. 1. 4. 
Blood, transfufion of in nervous fevers, 
xxxii. 4, 
deficiency of, xxxii. 2. and 4. 
from the vena portarum into 
the intellines, xxvii. 2. 
its momentum, xxxii. 5. 2. 
momentum increafed by vene- 
feCtion, xxxii. 5. 4. 
drawn in nervous pains, xxxii. 
5- 4- 
its oxygenation, xxxviii. 
Breathing, how learnt, xv. 4. 
Breafts of men, xiv. 8. 
Brutes differ from men, xi. 2. 3. xvi. 17. 
See Animals. 
Buxton bath, why ■ it feels warm, xii. 
2. 1. xxxii. 3. 3. 
C. 
Capillary veffels are glands, xxvi. 1. 
Catalepfy, xxxiv. 1. 5. 
Catarrh from cold fkin, xxxv. 1. 3. 
xxxv. 2. 3. 
from thin caps in fleep,xviii. 15. 
Catenation of motions defined, ii. ji, 
iv. 7. 
caufe of them, xvii. r. 3. 
defcribed, xvii. 
continue fome time after 
their production, xvii. 
voluntary ones diffevered 
in fleep, xvii. 1. 12. xvii. 
3« r3* 
Cathartics, external, their operation, 
xxix. 7. 6. 
Caufation, animal, defined ii. n. iv. 7. 
Caufe of caufes, xxxix. 4. 8. 
Caufes inert and efficient, xxxix. 12. 2. 
adtive and paffive, xxxix. 12. 3. 
proximate and remote, xxxix. 
12. 4. 
Chick in the egg, oxygMjatioh of, 
xxxviii. 2. 
Child riding on a flick, xxxiv. 2. 6. 
Chilnefs after meals, xxi. 3. xxxv. 1. 1. 
Cholera,cafe of, xxv. 13. 
Chyle, xxxix 11. 
Circulation in the eye vifible, xl. 10. 4. 
Cold in the head, xii. 7. 5. 
perceived by the teeth, xxxii. 3. 
1. xiv. 6. 
air, ufes of in fevers, xxxii. 3. 3. 
feet, produces coryza, xxxv. 2. 
3. xxxv. t. 3. 
bath, why it flrengthens, xxxii. 
5- 
fhort and cold breathing in it, 
xxxii. 3. 2. 
produces a fever fit, xxxii. 3. 2. 
fit of fever the confequence of 
hot fit, xxxii. 9. 3. 
bathing in pulmonary haemor- 
rhage, xxvii. 1. 
fits of fever, xxxii. 4. xxxii. 9. 
xvii. 3. 3. 
not a flimulus, xxxii. IO. 
Comparing ideas, xv. 3. 
Confcioufncfs, xv. 3. 4. 
in dreams, xviii. 13. 
Confumption, its temperamenti xxxi. 
1. and 2. 
of dark-eyed patients, 
xxvii. 2. 
of light-eyed patients, 
xxviii. 2. 
is contagious, xxxiii. 2.7. 
Confent of parts. See Sympathy. 
Contagion, xii. 3. 6. xix. 9. xxxiii. 2. 6. 
and 8. xxii. 3. 3. 
does not enter the blood, 
xxxiii. 2. 10. xxii. 3. 3. 
Contraction and attraction, iv. 1. 
of fibres produces fenfa- 
tion, iv. 5. xii. I. 6. 
continues feme time, xii. 
!• 5- 
alternates with relaxation, 
xii. 1. 3. 
Convulfion, xvii. r. 8. xxxiv. 1. 1. and 
4. iii. 5. 8. 
of particular mufcles,xvii. 
i.8. 
periods of, xxxvi. 3. 9. 
Colours of animals, efficient caufe of, 
xxxix. 5. 1. 
of eggs from female imagina- 
tion, xxxix. 5. 1. 
of the choroid coat of the eye, 
xxxix. 5. 1. 
of birds' nefts, xvi. 13. 
Coryza, INDEX TO THE SECTIONS.-Part I. 
85 
Coryza. See Catarrh. 
Cough, nervous, periods of, xxxvi, 
3- 9- 
Cramp, xviii. 15. xxiv. 1. 7. 
Critical days from lunations, xxxvi. 4. 
Cuckoo, xvi. 13. 5. 
D. 
Darkifh room, why we fee well in it. 
xii. 2. 1. 
Debility, fenforial and flimulatory, xii. 
2. 1, 
direCb and indirect of Dr. 
Brown, xii. 2. I. xxxii. 3. 2. 
See Weaknefs. 
from drinking fpirits, cure of, 
xii. 7. 8. 
in fevers, cure of, xii. 7, 8. 
Deliberation, what, xxxiv. 1. 
Delirium, two kinds of, xxxiii. 1. 4. 
xxxiv. 2. 1. 
cafes of, iii. 5. 8. 
prevented by dreams, xviii. 2. 
Defiie, origin of, ^i, 2. 3. 
Diabetes explained, xxix. 4. 
with bloody urine, xxvii. 2. 
in the night, xviii. 15. 
Diarrhwa, xxix. 4. 
Digeftion, xxxiii. 1. xxxvii. 
ftrengthened by emetics, 
xxxv. 1. 3. 
ftrengthened by regular 
hours, why, xxxvi. 2. 1. 
Digitalis, ufe of in dropfy, xxix. 5. 2. 
Diftention aCts as a ftimulus, xxxii. 4. 
See Extenfion. 
Diftinguifhing, xv. 3. 
Diurnal circle of actions, xxv. 4. 
Doubting, xv. 3. 
Dreams, viii. 1. 2. xiv. 2, 5. 
their inconfiftency, xviii. 16. 
no furprife in them, xviii. 17, 
much novelty of combination, 
xviii. 9. 
Dropfies explained, xxix. 5. 1. 
Dropfy cured by infanity, xxxiv. 2. 7. 
cure of, xxix. 5. 2. 
Drugkennefs. See Intoxication, xxi. 
diminiflied by attention, 
xxi. 8'. 
Drunkards weak till next day, xvii. 1.7. 
Hammer, and ftagger, and 
weep, xii. 4. r. xxi. 4. 
fee objedts double, why, 
xxi. 7. 
become delirious, fleepy, 
ftupid, xxi. 5. 
Dyfpncea in cold bath, xxxii. 3. 2. 
E 
Ear, a good one, xvi. io. 
noife in, xx. 7. 
Eggs of frogs, fifh, fowl, xxxix. 2. 
of birds, why fpotted, xxxix. 5. 
with double yolk, xxxix. 4. 4. 
Electricity, xii. 1. xiv. 9. 
jaundice cured by it,xxx.2. 
animal, xiv. 5. 
Embryon produced by the male, 
xxxix. 2, 
confifts of a living fibre, 
xxxix. 4. 
abforbs nutriment, receives 
oxygen, xxxix. i» 
its actions and fenfations, 
xvi. a. 
Emetic. See vomiting. 
Emotions, xi. 2. a. 
Ennui, or txdeum vitte, xxxiv. 2, 3, 
xxxiii. j. 1. xxxix. 6. 
Epileptic fits explained, xxxiv, 1, 4. 
xxvii. 2. 
in fleep, why, xviii. 14. 
and 15. 
Equinoxial lunations, xxxii. 6. 
Excitability perpetually varies,xii. 1.7. 
fynonymous to quantity of 
fenforial power, xii. 1.7. 
Exercife, its ufe, xxxii. 5. 3. 
Exertion of fenforial power defined, 
xii. a. 1. 
Exiftence in fpace, xiv. 2. 5. 
Extenfion, fenfe of, xiv, 7, 
Eyes become black in fome epilepfies, 
xxvii, a. 
F. 
Face, flufliing of after dinner, xxxv, 
1. 1. 
why firft affedled in fmall-pox, 
xxxv. 1. 1. 
red from inflamed liver, xxxv. a. 2. 
Fainting fits, xii. 5. 1. xiv. 7. 
Fear, language of, xvi. 8. 1. 
a caufe of fever, xxxii. 8. 
caufe of, xvii. 3.7. 
Fetus. See Embryon, xvi. 2. xxxix. i_. 
Fevers, irritative, xxxii. 1. 
intermittent, xxxii. 1. xxxii. 3. 
fenfilive, xxxiii. t. 
not an effort of nature for re- 
lief, xxxii. 10. 
paroxyfms of, xii, 7. 1. xii. 2; 
3- xii. 3.5. 
why fome intermit and not 
others, xxxvi. 1. 
cold fits of, xxxii. 4. xxxii, gr, 
xvii. 3. 3. 
Fevers^ 86 
INDEX TO THE SECTIONS.-Part I. 
Fevers, periods of, xxxvi. 3. 
have folar or lunar periods, 
xxxii. 6. 
fource of the fymptoms of, 
xxxii. 1. 
prollration of ftrength in, xii. 
4. i. xxxii. 3. 2. 
cure of, xii. 6. 1. 
how cured by the bark.xii.3 4. 
cured by increafed volition, 
xii. 2. 4. xxxiv. a. 8. 
bell quantity of (iimulus in, 
xii. 7. 8. 
Fibres. See Mufcles. 
their mobility, xii. 1. 7. xii. i.t. 
contractions of, vi. xii. 1. 1. 
four clafles of their motions, vi. 
their motions di ftinguifhed from 
fenforial ones, v* 3. 
Figure, xiv. 2. 2. iii. 1. 
Fifh, their knowledge, xvi. 14. 
Foxglove, its ufe in dropfies, xxix. 5. 2. 
overdofe of, xxv. 17. 
Free-will, xv. 3. 7. 
G. 
Gall-flone, xxv. 17. See Bile-ftones. 
Generation, xxxiii. 1. xxxix. 
Gills of fifh, xxxviii. 2. 
Glands,xxii. 1. conglobate glands,xxii.2. 
have their peculiar ftimulus, 
xi. 1. 
their fenfes, xiv. 9. xxxix. 6. 
invert their motions, xxv. 7. 
increafc their motions, xxv. 7. 
Goldenrulefor exhibitingwine, xii. 7.8. 
for leavingoffwine,xii.7.8. 
Gout from inflamed liver, xxxv. 2. 2. 
xviii. 15. xxiv. 2. 8. 
in the flomach,xxiv. 2. 8,xxv. 17. 
why it returns after evacuations, 
xxxii. 4. 
owingtovinousfpiritonly, xxi.io. 
periods of, xxxvi. 3. 6. 
Grinning in pain, xxxiv. 1. 3. 
Gyration on one foot, xx. 5. and 6. 
H. 
Habit defined, ii. 11. iv. 7. 
Hemorrhages, periods of, xxxvi. 3.1:. 
from paralylis of veins, 
xxvii. 1. and 2. 
Hair and nails, xxxix. 3. 2. 
colour of, xxxix. 5. 1. 
H armony, xxii. 2. 
Head-achs, xxxv. 2. I. 
Hearing, xiv. 4. 
Heat, fenfe of, xiv. 6. xxxii. 3. t. 
produced by the glands, xxxii. 3. 
external and internal, xxxii. 3.1. 
atmofphere of heat, xxxii. 3. 1. 
increases during deep, xviii. 15. 
Hetnicrania, xxxv. 2. 1. 
from decaying teeth , xxxv.2. t. 
Hepatitis, caufe of, xxxv. 2. 3. 
Hereditary difeafes, xxxix. 7. 6. 
Hermaphrodite infects, xxxix. 5. 
Herpes, xxviii. 2. 
from inflamed kidney, xxxv.2.2. 
Hilarity from diurnal fever, xxxvi.3.1. 
Hunger, fenfe of, xiv. 8. 
Hydrophobia, xxii. 3. 3. 
Hypochondriacifm, xxxiii. 1.1. xxxiv. 
*• 3* 
I. 
Ideas defined, ii. vi. 2. 7. 
are motions of the organs of fenfe, 
iii. 4. xviii. 5. xviii. 10. xviii. 6. 
analogous to mufcular motions, 
iii. 5- 
continue fome time, xx. 6. 
new ones cannot be invented, 
iii. 6. 1. 
abftradtcd ones, iii. 6.4. xv. 5. 
inconfiftent trains of, xviii. 16. 
perilh with the organ of fenfe, 
iii. 4. 4. 
painful from inflammation of the 
organ, iii. 5. 5. 
irritative ones, vii. I. 4. vii. 3. 2. 
xv. 2. xx. 7. 
of refemblance, contiguity, cauf- 
ation, viii. 3. 2. x. 3. 3. 
refemble the figure, and other 
properties of bodies, xiv. 2. 2. 
received in tribes, xv. 1. 
of the fame fenfe cafier combin- 
ed, xv. 1. 1. 
of reflection, xv. 1. 6, ii. 12. 
Ideal prefence, xv. 1. 7. 
Identity, xv. 3. 5. xviii. 13. 
Iliac paflion, xxv. 15. 
Imagination, viii. 1. 2. xv. 1. 7. xv.2.2. 
of the male forms the 
fex, xxxix. 6. 
Immaterial beings, xiv. 1. xiv. 2. 4. 
Imitation, origin of, xii. 3. 3. xxxix. 5 
xxii. 3. xvi. 7. 
Impediment of fpeech, xvii. 1.10. xvii. 
2. 10. 
Infection. See Contagion. 
Inflammation, xii. 2. 3. xxxiii. 2. 2. 
great vafcular cxertiok 
in, xii. 2. 1. 
Inflammation, INDEX TO THE SECTIONS.-Part I. 
87 
Ihflammation not from pains from de- 
fect of ftimulus. xxxiii. 
a. 3- 
of parts previoufly in- 
fenfible, xii. 3. 7. 
often diftant from its 
caufe, xxiv. 8. 
obferves folar days, 
xxxii. 6. 
of the eye, xxxiii. 3.1, 
of the bowels prevented 
by their continued 
adlion in deep, xviii.2. 
Inoculation with blood, xxxiii. 2. 10. 
Infane people, their great ftrength,xii.i. 
Infanity (fee Madnefs) pleaiurableone, 
xxxiv. 2. 6. 
Infedts, their knowledge, xvi. rj . & t6. 
in the heads of calves, xxxix. 1. 
clafs of, xxxix. 4. 8. 
InftinClivc adtions defined} xvi. 1. 
Inteftines, xxv. 3. 
Intoxication relieves pain, why, xxi. 3. 
from food after fatigue, 
xxi. 2. 
difeafes from it, xxi. 10. 
See Drunkennefs. 
Intuitive analogy, xvii. 3. 7. 
Invention, xv. 3. 3. 
Irritability increafes during deep, 
xvi.i. 15. 
Itching, xiv. 9. 
Jaw, locked, xxxiv. 1. 5. 
Jaundice from paralyfis of the liver, 
xxx. 2. 
cured by eledlricity, xxx. 2. 
Judgment, xv. 3. 
K. 
Knowledge of various animals, xvi. 11. 
L. 
Lacrymal fack, xvi. 8. xxiv. 2. and 7. 
Ladteals, paralyfis of, xxviii. Sec Ab- 
forbents. 
Lady playing on the harpficherd, 
xvii. 2. 
diftrefled for her dying bird, 
xvii. 2. 10- 
Language,natural, its origin,xvi, 7>& 8. 
of various palHons defcrib- 
ed, xvi. 8. 
artificial, of various animals, 
xvi. 9. 
theory of, xxxix. 8. 3. 
I.apping of puppies, xvi. 4. 
Laughter explained, xxxiv. 1. 4. 
from tickling, xvii. 3. 5. 
xxxiv. 1. 4. 
from frivolous ideas, xxxiv. 
1. 4. xviii. 12. 
Vol. IL Z z z 
Life, long, art of producing, xxxvii. 
Light has no momentum, lii. 3. 1. 
Liquor amnii, xvi. 2. xxxviii. 3. xxxix, 
I. 1. 
is nutritious, xxxviii. 3. 
frozen, xxxviii. 3. 
Liver, paralyfis of, xxx. 1. 4. 
large of geefe, xxx. 1. 6. 
Love, fentimental, its origin, xvi. 6. 
animal, xiv. 8. xvi. 5. 
Lunar periods affedt difeafes, xxxii. 6. 
Luft, xiv. 8. xvi. 5. 
Lymphatics, paralyfis of, xxviii. See 
Abforbents. 
M. 
Mad-dog, bite of, xxii. 3. 3. 
Madnefs, xxxiv. 2. x. xii. 2. x. 
Magnetifm, xii. x. 1. 
Magnifying objects,new way of, xl. 10.5. 
Male animals have teats, xxxix. 4. 8. 
pigeons give milk, xxxix. 4. 8. 
Man diftinguifhed from brutes, xi. 2. 
3. xvi. 17. 
Material world, xiv. i.xiv. 2.5. xviii. 7. 
Matter, penetrability of, xiv. 2. 3, 
purulent, xxxiii. 2. 4. 
Mealies, xxxiii. 2. 9. ' 
Membranes, xxvi. 2. 
Memory defined, ii. 2.10. xv.x. 7.XV. 3. 
Menftruatien by lunar periods, xxxii. 6. 
Microfcopic animals, xxxix. 11. 5. 
vegetables, xxxix. 11.1. 
Mifcarriage from fear, xxxix. 6. 5. 
Mobilty of fibres, xii. 1. 7. 
Momentum of the blood, xxxii. 5. 2. 
fometimes increafed by 
venefedtion, xxxii. 5. 4. 
Monftcrs, xxxix. 4. 4. and 5. 2. 
without heads, xxxviii. 3. 
Moon and fun, their influence, xxxii. 6. 
Mortification, xxxiii. 3. 3. 
Motion is either caufe or effedt, i. xiv. 
2.2. 
primary and fecondary, i. 
animal, i. iii, 1. 
propenfity to, xxii. T. 
animal, continue fome time 
after their production, xvii. 
3* 
defined, a variation of figure, 
iii. 1. xiv. 2. 2. xxxix. 7. 
Mucus, experiments on, xxvi. 1. 
fecretion of, xxvi. 2. 
Mules, xxxix. 4. 5. and 6. xxxix. 5. 2. 
Mule plants, xxxix. 2. 
Mufcx volitantes, xl. 2. 
Mufcles conftitute an organ of fenfe, 
xiv. 7. ii. 3. 
ftimnlated by extenfion, xi. I. 
xiv. 7, 
Mufcles 88 
INDEX TO THE SECTIONS.-Part I. 
Mufclescontradl by fpiritof animation, 
xii. 1. 1. and 3. 
Mufic, xvi. 10. xxii. 2. 
Mufical time, why agreeable, xii. 3.3. 
N. 
Naufea, xxv. 6. 
Nerves and brain, ii. a. 3. 
extremities of, form the whole 
fyftem, xxxvi i. 3. 
are not changed with age, xxxvii.4. 
Nervous pains defined, xxxiv. 1. 1. 
Number defined, xiv. 2. 2. 
Nutriment for the embryon, xxxix. 5.2. 
Nutrition owing to ftimulus, xxxvii. 3. 
by animal feledlion,xxxvii. 3. 
when the fibres are elongat- 
ed, xxxvii. 3. 
like inflammation, xxxvii. 3. 
O. . 
Objedls long viewed become faint, iii. 
3- 
Ocular fpectra, xl. 
Oil externally in diabetes, xxix. 4. 
Old age from inirritability, xxxvii. 
Opium is flimulant, xxxii 2. 2. 
promotes ablorpticn after e- 
vacuation, xxxiii. 2. 10. 
in increafing dofes, xii. 3. I. 
Organs of fenfe, ii. 2. 5. 
when deftroyed ceafe to pro- 
duce ideas, iii. 4. 4. 
Organic particles of Buffon, xxxvii. 3. 
xxxix. 3. 3. 
Organ pipes, xx. 7. 
Oxygenation of the blood, xxxviii. 
P. 
Pain from excefs and defect of motion, 
iv. 5. xii. 5. 3. xxxiv. 1. xxxv. 
a. 1. 
not felt during exertion, xxxiv. 
I. 2. 
from greater contraction of fi- 
bres, xii. 1. 6. 
from accumulation of fenforial 
power, xii. 5. 3. xxiii. 3. 1. 
from light, preflurc, heat, cauf- 
tics, xiv. 9. 
in epilcpfy, xxxv. 2. I. 
diflant from its caufe, xxiv. 8. 
from ftone in the bladder, xxxv. 
2. I. 
of head and back from defect of 
heat, xxxii. 3. 
from a gall-flone, xxxv. 2. I. xxv. 
I7- 
of the flomach in gout, xxv. 17. 
of fhouldcr in hepatite.-, xxxv. 2.4. 
produces volition, iv.'6. 
Palenefs in cold fit, xxxii. 3. 1. 
Palfies explained, xxxiv. I. 7. 
Paralytic limbs flretch from irritation, 
vii. 1.3. 
patients move their found 
limb much, xii. 5. I. 
Paralyfis from great exertion, xii. 4. 6. 
from lefs exertion, xii. 5. 6. 
of the iadlcals, xxviii. 
of the liver, xxx. 4. 
of the right arm, why, xxxiv. 
1. 7. 
of the veins, xxvii. 1. 
Particles of matter will not approach, 
xii. 1. 1. 
Paflions, xi. 2. 1. 
connate, xvi. 1, 
Pecking of chickens, xvi. 4, 
Perception defined, xv. 3. 1. ii. 1. 8. 
Periods of agues, how formed, xxxii. 
3-4- 
of difeafes, xxxvi. 
of natural actions and of dif- 
eafed actions, xxxvi. 
Perfpiration in fever-fits, xxxii. 9. See 
Sweat. 
Petechix, xxvii. ». 
Pigeons fecrete milk in their (lemachs, 
xxxix. 4. 8. 
Piles, xxvii. 2. 
Placenta a pulmonary organ, xxxviii. 
2. 
Pleafurc of life, xxxiii. 1. xxxix. 5. 
from greater fibrous contrac- 
tions, xii. 1. 6. 
what kind caufes laughter, 
xxxiv. 1. 4. 
what kind caufes fleep, xxxiv. 
1. 4- 
Pleurify, periods of,xxxvi. 3. 7. 
caufe of, xxxv. 2. 3. 
Prometheus, ftory of, xxx. 3. 
Proflration of flrength in fevers, xii. 
41. 
Pupils of the eyes large,xxxi. 1. 
Puife quick in fevers with debility, xii 
1. 4. xii. 5. 4. xxxii. 2.1. 
in fevers with flrength, xxxii. 2. 
from defect of blood, xxxii. 2. 3. 
xii. 1. 4 
weak from emetics, xxv. 17. 
Qu . . . 
Quack advertifements injurious. Pref- 
ace. 
Quadrupeds have no fanguiferous lo- 
chia, xxxviii. 2. 
have nothing fimilar to the 
yolk of egg, xxxix. 1. 
Raphania, INDEX TO THE SECTIONS.-Part I. 
89 
R. 
Raphania, periods of, xxxvi. 3. 9. 
Reafon, ix. 1. 2. xv. 3. 
Reafoning, xv. 3. 
Recolle&ion, ii. 10. ix. T. 2. xv. 2. 3. 
Relaxation and bracing, xxxii. 3. 2. 
Repetition, why agreeable, xii. 3. 3- 
xxii. 2. 
Refpiration afledted by attention, 
xxxvi. 2. 1. 
Rcftieffnefs in fevers, xxxiv. r. 2. 
Retrograde motions, xii. J. 5. xxv. 6. 
xxix. 11. 
of the ftomach, xxv. 6. 
of the fkin, xxv. 9. 
of fluids, how diftinguifhed, 
xxxix. 8. 
how caufed, xxix. II. 5. 
Retrograde vegetable motions, xxix. 9. 
Retina is fibrous, iii. 2. xl. 1. 
is a&ive in vifion, iii. 3. xh r, 
excited into fpafmodic motions, 
xh 7- 
is fenfible during fleep, xviii. 5. 
xix. 8. 
Reverie, xix 1. xxxiv. 3. 
cafe of a flecp-walker,"xix. 2. 
is an epileptic difeafe, xix. 9. 
Rhymes iu poetry, why agreeable, 
xxii. 2. 
Rheumatifm, three kinds of, xxvi. 3. 
Rocking young children, xxi. 4. 
Rot in fheep, xxxii. 7. 
Ruminating animals, xxv. I. 
S. 
Saliva produced by mercury, xxiii. 
by food, xxiii. 1. 
by ideas, xxiii. 2. and 5. 
by difordered volition, xxiii, 7. 
Scirrhous tumours revive, xii. 2. 2. 
Screaming in pain, xxxiv. 1. 2. 
Scrofula, its temperament, xxxi. 1. 
xxviii. 2. xxxix. 4. 5. 
Scurvy of the lungs, xxvii. 2. 
Sea licknefs, xx. 4. 
(lopped by attention, xx. 5. 
Secretion, xxxiii. 1. xxxvii. 
increafed during deep, xviii. 16. 
Seeds require oxygenation, xxxviii. 2. 
Senfationfiefined, ii. 2. 9. v. 2. xxxix. 8.4 
difeafes of, xxxiii. 
from fibrous contradliuns, 
iv. 5. xii. 1. 6. 
in an amputated limb, iii.7.3. 
aflcdls the whole fenforium, 
xi. 2. 
produces volition, iv. 6. 
Senfibility increafes during fleep, xviii. 
f-5- 
Senfltitive motions, viii. xxxiii. 2. 
xxxiv. i. 
fever* oftwo kinds, xxxiii.1.2. 
ideas, xv. 2. 2. 
Senformm defined, ii. 2. r. 
Senfes correct one another, xviii. 7. 
diftinguifhed from appetites, 
xxxiv. 1. 1. 
Senforial power. See Spirit of Ani- 
mation. 
great expcnfe of in the vital 
motions, xxxii. 3. 2. 
two kinds of exerted in fen- 
firive fevers, xxxiii. 1. 3. 
powers defined, v. i. 
motions diftinguiflied from 
fibrous motions, v. 3. 
not much accumulated in 
deep, xviii. 2. 
powers,accumulation of, xii. 
5- I- 
exhauftion of, xii. 4. r. 
wafted below natural in hot 
fits, xxxii. 9. 3. 
lefs exertion of produce* 
pain, xii. 5. 3. 
lefs quantity of it, xii. 5. 4. 
Senfual motions diftinguiflied from 
mufcular, ii. 7. 
Sex owing to the imagination of the 
father, xxxiv. 5. xxxix. 7. 6. xxxix. 
6. 3. xxxix. 6. 7. 
Shingles from inflamed kidney, xxxr. 
2. 2. 
Shoulders broad, xxxi. r. xxxix. 7. 6. 
Shuddering from cold,xxxiv. r. i.& 2. 
Sight, its accuracy in men, xvi. 6. 
Skin, feurfon it, xxvi. 1. 
Sleep fufpends volition, xviii. 1. 
defined, xviii. 21. 
remote caufes, xviii. 20. 
fenfation continues in it, xviii. t 
from food, xxi. 1. 
from rocking, uniform founds, 
xxi. 1. 
from wine and opium, xxi. 3. 
why it invigorates, xii. 5. r. 
pulfe flower and fuller in, xxxii. 
2. 2. 
interrupted, xxvii. 2. 
from breathing lefs oxvgene, 
xviii. 20. 
from being whirled on a mill- 
done, xxiii. 20. 
from application of cold,xviii.20. 
induced by regular hours,xxxvi. 
2. 2. 
Sleeping animals, xxi. 2. 2. 
Sleep-walkers, See Reverie, x'x. r. 
Small-pox, 90 
INDEX TO THE SECTIONS.-Fart I. 
Small-pox, xxxiii. 2. 6. xxxiv. 6. 1. 
eruption firfl on the face, 
why, xxxv. 1. 1. xxxiii. 
2. 10. 
the blood will not infect, 
xxxiii. 2. to. 
obeys lunations, xxxvi. 4. 
Smell, xiv. 5. xvi. 5. . 
Smiling, origin of, xvi. 8. 4. 
Solidity, xiv. j. 1, 
Somnambulation. See Reverie, xix.1. 
Space, xiv. 2. 2. 
Spafm, dodtrine of, xxxii. 10. 
Spedlra, ocular, xl. x 
miftaken for fpedfres, xl. 2. 
vary from long infpedtion, iii. 
3-5- 
Spirit of animation. See Scnforial 
Power. 
of animation caufes fibrous con- 
tradtion, iv. 2, ii. 1. xiv. 2. 4. 
poffefles folidity, figure, and oth- 
er properties of matter, xiv. 
2- 3- 
Spirits and angels, xiv. 2. 4. 
Stammering explained, xvii. T. 10. 
xvii. 2. to. 
Stimulus defined, ii. 2. 13. iv. 4. xii. 2.1. 
of various kinds, xi. 1. 
with leflened effedt, xii. 3 1. 
with greater effedt, xii. 3. 3. 
ceafes to produce fenfation, 
xn 3. 3- 
Stomach and inteftines, xxv. 
inverted by great ftimulus, 
xxv. 6. 
its adtions decreafed in vom- 
iting, xxxv. 1.3. 
a blow' on it occaftcns death, 
xxv. 17. 
Stools black, xxvii. 2. 
Strangury, xxxv. 2. 1. 
Sucking before nativity, xvi. 4. 
Suckling children, fenfe of, xiv. 8. 
Suggeffion defined, ii. 10. xv. 2. 4. 
Sun and moon, their influence, xxxii.6. 
Surprife, xvii. 3.7. xviii. 17. 
Sufpicion attends madnefs, xxxiv. 2. 4. 
Swallowing, adl of, xxv. r. xvi. 4. 
Sweat, cold, xxv. 9. xxix. 6. 
in hot fit of fever, xxxii. 9. 
in a morning, why, xviii. rj. 
Sweaty' hands cured by lime, xxix. 
4 9- 
Swinging and rocking, why agreeable, 
xxi. 3. 
Sympathy, xxxv. 1. 
Syncope, xii. 7. 1. xxxiv. 1. 6. 
T. 
Txdum vitx. See Ennur. 
Tape-worm, xxxix. 2.3. 
Tafte, fenfe of, xiv. 5. 
Tears, fecrction of, xxiv. 
from grief, xvi. 8. 2. 
from tender pleafure, xvi. 8. 3- 
from ftimulus of nafal dudt, xvi. 
8. xxiv. 4. 
by volition, xxiv. 6. 
Teeth decaying caufe hcadachs, xxxv. 
2. 1.. 
Temperaments, xxxi. 
Theory of medicine, wanted. Preface* 
Thirft, fenfe of, xiv. 8. 
why in dropfies, xxix. 5. 
Tickle themfelves, children cannot, 
xvii. 3. 5. 
Tickling, xiv. 9. 
Time, xiv. 2. 2. xviii, 12. 
lapfe of, xv. 3. 6. 
poetical and mulical, why agree- 
able, xxii. 2. 
dramatic, xviii. 12. 
Tooth-edge, xvi. 10. iii. 4. 3. xii. 3. 3^ 
Touch, fenfe of, xiv. 2 1. 
liable to vertigo, xxi. 9. 
of various animals, xvii 6. 
Trains of motions inverted, xii. 5. 5. 
Transfufion of blood in nervous fever, 
xxxii. 4. 
Tranflations of matter, xxix. 7. 
Typhus, belt quantity of ftimulus in, 
xii. 7. 8. 
periods of, obferve lunar 
days, xxxii. 6. 
• U. 
Ulcers, art of healing, xxxii. 3. 2. 
of the lungs, why difficult to 
heal, sxviii. 2. 
Uniformity in the fine arts, why agree- 
able, xxii. 2. 
Urine pale in intoxication, xxi. 6. 
paucity of in anafarca, why, 
xxix. 5. 
its paffage from inteftincs to 
bladder, xxix. 3. 
copious during deep, xviii. 15. 
V. 
Variation, perpetual,of irritability, xii. 
2. I. 
Vegetable buds are inferior animals, 
xiii. I. 
exactly refemhie their 
parents, xxxix. 
poifefs fenfation and 
volition, xiii. 2. 
Vegetable INDEX TO THE SECTIONS.-Part I. 
91 
Vegetable buds have affociate and re- 
trograde motions, xiii. 
4. xxix. 9. 
their anthers and fligmas 
are alive, xiii. 5. 
Vegetables have organs of fenfe and 
ideas, xiii. 5. 
contend for light and air, 
xxxix. 4. 8. 
duplicature of their flow- 
ers, xxxix. 4. 4. 
Veins are abforbents, xxvii. 1. 
paralyfis of, xxvii. 1. 
Venereal orgafin of brutes, xxxii. 6. 
Venefedtion in nervous pains, xxxii.54. 
Verbs of three kinds, xv. 3. 4. 
Verfes, their meafure, xxii. 2. 
Vertigo, xx. defined, xx. 11. 
in looking from a tower, xx.i. 
in a fhip at fea, xx. 4. 
of all the fenfes, xxi. 9. 
by intoxication, xxxv. I. 2. 
Vibratory motions perceived after fail- 
ing, xx. 5. xx. 10. 
Vinegar makes the lips pale, xxvii. 1. 
Vis medicatrix of nature, xxxix. 4. 7. 
Vifion, fenfe of, xiv. 3. 
Volition defined, v. 2. xxxiv. r. 
affedts the whole fenforium, 
xi. 2. 
Volition, difeafes of, xxxiv. 
Voluntary, x. 2. 4. 
motions, ix. xxxiv. I. 
ideas, xv. 2. 3. 
criterion of, xi. 2. 3. 
xxxiv. 1. 
Vomiting from vertigo, xx. 8. 
from druukennefs, xx. 8. 
xxi. 6. 
by intervals, xxv. 8. 
by voluntary efforts, xxv. 
6. 
of two kinds, xxxv. 1. 3. 
in cold fit of fever, xxxii. 
9. 1. 
flopped by quickfilver, xxv. 
16. 
weakens the pulfe, xxv. 17, 
W. 
Waking, how, xviii. 14. 
Walking, how learnt, xvi. 3. 
Warmth in deep, why. xviii. 15. 
Weaknefs defined, xii. 1. 3. xii. 2. r. 
xxxii. 3. 2. 
cure of, xii. 7 8. See De- 
bility. 
Wit producing laughter, xxxiv. 1. 4, 
World generated, xxxix. 4. 8. 
Worm, fluke, xxxii. 7. 
END OF INDEX TO PART I. 
[(Lz* Part II. and the Index to it, compofe the Secon© Volume. J 
Vol. I. 
A A a a 
INDEX INDEX 
OF THE 
ARTICLES OF PART THIRD. 
A BSORPTIOH iv. 2,1. 
cutaneous, mucous, cellu- 
lar, iv. 2, 2. 
of the veins, iv. 2,4. 
of inflamed veflels, iv. 2, 
4, 3- 
of inteflines and liver, iv. 
1,5- 
of venereal ulcers, iv.2,7. 
not increafed by cold, 
iv. 2, 1. 
increafed by opium after 
evacuation, ii. 2, I. 
by faline bath, iv. 2, 3, 8. 
by abftinencefrom fluids, 
iv. 2, 3,9. 
Acacia, iv. 3, 5, 2. 
Acids auiflere, iv. 2, I, 2. iv. 3, I. 
vegetable, fweet, vii. 3,4.iv.2,1,2. 
mineral, vii. 3, 6. 
Acrid plants, iv. 2, 4. 
Agriculture, i. 2, 3, 7. 
Agues, three kinds, iv. 2, 3, 2. iv. 2, 5. 
iv. 2, 6, 8. 
Air nourifhes, i. 2, 5. 
warm bath of, iv. 2, 3, 8. 
Alcali vol. iii. 3, 3. 
Alcohol, ii. 2, 1. v. 2, 4. 
Almond, hitter, ii. 3, 1. 
Althrea, iii. 3, 3, 3. 
Allium, iii. 3, 3. 
Aloe, iii. 2, 5. iii. 2,7. iii. 3, 5, 5. vi. 2, 5. 
Alum, iii. 2, I. iv. 2,1, iv. 2, 5, 2. iv. 3, 
5. 3: 
to purify water, i. 2,4, 2. 
Amalgama in worms, vii. 2, 2. 
Amomum zinziber, iii. 3, I. 
Amber, oil of, vi. 3, 4. 
Ammoniac gum, vi. 3, 1, iii. 3, 3. 
fait or fpirit, iii. 3, 3. 
Anarfarca, warm bath in,ii. 2, 2. iv. 2, 
3, 8- 
Anchovy, iii. 2, I. iii. 3, 1,4. 
Animal food, i. 2, I, I. 
Antimony prepared, iii. 3, I, 5. iii. 2, 
1. iv. 1, 10. 
Anthemis nobilis, iv. 3, 3. 
pyrethrum, iii. 3, 2. 
Anxiety, v. 2, 4. 
Apium, petrofelinum, iii. 3, 4, 4. 
Apoplexy, iv. 2, II. 
Ariftclochia ferpentaria, iii. 3, 1. 
Armenian bole, vi. 2, 3. vi. 3, 5, 3. 
Arfenic in ague, iv. 2, 6, 8. iv. 3, 6. 
faturated folution of, iv. 2,6, 8. 
in itch, iv. 2. 9. 
how it adts, iv. 2, 6, 9. 
how to detedl it, iv. 2, 6, i» 
ArtemiGa maritima, iv. 3, 3. 
abfynthium, iv. 3, 3. 
fantonicum, iv. 3, 3. 
Artichoke-leaves, iv. 3, 3. 
Afafcetida, ii. 3. vi. 3, 1. 
Afarum Europeum, v. 3, 3. 
Afcarides, vii. I, 2. iii. 2, 9, 7. 
Afparagus, iii. 3, 4,4. 
Aftragalus tragacantha, iii. 3, 3,3. 
Atropa belladonna, ii. 3, 1. 
Azote, i. 2, 5. 
B. 
Balfams diuretic, iii. 2, 4. 
Bandages promote abforption,iv. 2.1*. 
Bark, Peruvian, iv. 2, 2. 
longufed noxious, iv. 2, 11. 
Barley, iii. 3, 3, 3. 
Bath, warm, ii. 2, 2, I, iii. 3, I, 6, iii. 
3, 3, 4. iii. 2, 3,3. 
faline, iv. 2, 3, 8. 
cf warm air, iv, 2, 3, 8. 
Bath, INDEX OF THE ARTICLES.-Part III. 
93 
Bath, of fleam, iv. 2, 3,8. 
cold, vii. 2, 3. 
nutritive, i. 2, 6,1. 
Benzoin, iii. 3,3. 
Bile of animals, iii. 2, 5, 2. 
dilute Rate of, iv. 2, 6. 
BliRers, how they aCt, iii. 2, 1,10. 
cure heart-burn, iii. 2, 1,10. 
• flop vomiting, vi. 2, 2. 
produce expectoration, iii. 2, 
3» 
increafe perfpiration, iii. 2, I. 
10. 
Blood, transfufion of, i. 2, 6, 2. 
Bog-bean, iv. 3, 3. 
Bole armenian,iv. 2, 5, 3. 
Bone-aflres, iv. 3, 5, 3. 
Bowels, inflammation of, v. 2, 2, 2. 
Bryony, white, iii.,3, 8. 
as a bliRer, iii. 2, 9. 
Butter, i. 2, 3, 2. 
Butter-milk, i. 2, 2, 2. 
C. 
Cabbage-leaves, vii. 1, 2. 
Calcareous earth, i. 2,4, 3. 
Calomel, iii. 2, J. vi. 2, 5. 
in enteritis, v. 2, 2, 2. 
Camphor, iii. 3, 1. 
Canella alba, iii. 3, 1. 
Cantharides, iii. 2, 6. iii. 2, 8. v. 2, 4. 
vi. 2, 4. 
Capillary aCtion increafed by tobacco, 
iv. 2, 3, 7. 
Capficum, iii. 3, 1. 
Carbonic acid gas, vii. 2, 6. 
Cardamomum, iii. 3, 1. 
Caryophyllus aromat. iii. 3, K 
Cardamine, iv. 3, 4. 
Callia fiRul. iii. 3,5, r. 
fenna, iii. 3, 5, 5. 
CaRor, vi. 2, 1. vi. 3, 1. 
Cathartics, mild, iii. 2, 5. 
violent, v. 2, 2. 
Cerufla ih ulcers, iv. 2, 9. iv. 2, 7. 
Chalk, iv. 3, 5, 3. 
Chalybeates, iv. 3,4, 2. iv. 3, 6, 6. 
Chalybeate powder, iv. 2, 6, 6. 
Cheefe, i. 2, 2, 3. 
Cherries, black, ii. 2, I, 8. 
Chlorofis, iv. 2, 6, 5. 
Cicuta,ii.3, I. 
Cinchona, iv. 2, 2. 
Cinnamon, iii. 3,2., 
Clay, iv. 3, 5, 3. 
Cloves, iii. 3, 1. iii. 3, 2. 
Cnicus acarna, v. 3, 1. 
QqccuIus indicus, ii. 3, 1, 
Cochlearia armoracia, iii. 3, 8. iv. 3,4^ 
hortenfis, iv. 3, 4. 
Cold,continued application of, vii. 2,3. 
interrupted, vii. 2, 3. iii. 3, 1, 7. 
exceffive, vii. 2, 3. 
firR effedls lymphatics, vii. 2, 3. 
produces rheum from the nofe, 
vii. 2, 3. 
produces quick anhelation, vii. 
a, 3- 
increafes digefiion, vii. 2, 3. 
Cold-fit eafier prevented than remov- 
ed, ii. 2, 1. 
Colic from lead,v. 2, 2,2. 
Condiments, i. 2, 7. 
Convolvulus fcammonium, v. 3,2. 
Convullions, iv. 2, 8. 
Cookery, i. 2, 3, 5. 
Copaiva balfam, iii. 3, 4, 3- 
Cowhage, iii. 2, 7- vii. 3> 
Crab-juice, iv. 2, 2. 
Cream,i. 2,3, 2. i. 2, 2, 2. 
Cucumis celocynthis, v. 3, 2. 
Cynara fcolymus, iv. 3, 3. 
Cynogloffum, ii. 3, 1. 
D. 
Dandelion, iv. 3, 4. 
Datura flramonium, ii. 3, I. 
Daucus fylvcRris, iii. 3, 4, 4- 
Delphinium flavifagria, ii. 3, X. 
Diabetes, iv. 2, 5. 
warm bath in, vi. 2, 4. 
Diaphoretics, iii. 3,1. iii. 2, 1,2. 
belt in the morning, iii. 2, 
1, 5- 
Diarrhoea, vi. 2, 3. 
DigcRion injured by cold, iii. 2,1. 
increafed by cold, vii. 2, 3. 
Digitalis, iv. 2, 3, 7. v. 2, I, 2. 
tinClure of, iv. 2, 3, 7. 
Dragon's blood, iv. 3, 5, 2. 
Dropfy, iv. 2, 3,4. iv. 2,6,7. iv. 2,3, J. 
E. 
Ears, eruption behind, iv. 2, 9, 2. 
Earth of bones, iv, 2, 5. 
of alum, vi. 2, 4. 
calcareous, iv. 2, 5, 3; vi. 2,4. i. 
a, 4, 3- 
Eggs, *• a, 1, 4. 
Egg-fhells diuretic, iii. 2, 4. 
Electricity, ii. 2, 2, 2. iv. 2,9. 
Emetics, how they aCt,v. 2, 1. 
Errhincs mild, iii. 2, 9, 
in hydrocephalus, v. 2, 3, I. 
violent, v. 2, 3. 
in head-ach, v. 2, 3, I. 
Eryfipelas, iv. 2, 9. 
Eflential oils, ii. 2, 3. 
Ether,. 94 
INDEX OF THE ARTICLES.-Part III. 
Ether, vitriolic, ii. 2. 3. iii. 3. I. vi. 
3- 
in afcarides, vii. 1. 2. 
to purify, ii. i. 3. 
Etiolation, i 2. 3. 4. 
Euphojbium, v. 3. 31 
Exercife, iii. 3. 1. 6. ii. 2. 6. 
Eyes inflamed, ii. 2. 2. 2. iv. 2. 3. 
F. 
Famine, times of, i. 2. 3. 5. and 6. 
Fear, v. 2. 4. 
Feathers, fmoke of, vi. 3. 6. 
Fennel, iii. 3. 4- 4« 
Ferula afafertida. iii. 3. 3. 
Fifli, i. 2 1. 2. i. 2 1,5. 
Flannel fliirt, ii. 2. 2. 1. 
Fkfli of animals, i. 2, 1. 
Fluke-worm, iv. 2. 6. 
Foxglove, iv 2. 3. 7. v. 2. I. v. 2- 4. 
tincture of, iv. 2. 3. 7. 
Fridlion, ii. 2. 5. iii. 3.1. 6. 
G.' 
Galanthus nivalis, vii. 3. 3. 
Galbanum, vi. 3 1. 
Gall-fhpnes, iv. 2. 6, 
Galls of oak, iv. 3. 5. 
Garlic, iii. 3. 3. 
Gentiana centaureum, iv, 3. 3. 
lutea, iv. 3. 3. 
Ginger, iii. 3.1. iii. 3. 4. 
Gonorrhoea, iv. 2. 2. iii. 2.4. 
Gout, iv, 2 11. 2. 
Guaiacum,iii. 3.1. 
Gum arabic, iii. 3. 3. 3. 
tragacanth, iii. 3. 3. 3- 
Glycyrrhiza glabra, iii. 3. 3. 3. 
Gravel, v. 2. 4. 4. 
H. 
Hartfliorn, fpirit and fait of, iii 3. 3. 
iii. 3.1. vi. 3.4. 
calcined, iv. 2. J. vi. 2. 3. 
Haemorrhages, iv 2. 4. 4. iv. 2. C. 2. 
Hasmatoxyion campechianum, iv. 3. 
5. 2. 
Hay, infuGon of, i. 2. 3. 6. 
Head-ach, fniiff in, v. 2. 3. 1. 
Heat, ii. 2. 2. r. See Bath. 
an universal folvcnt, vii. 2. 2. 
Helenium, iii. 3.3. 2. 
Herpes, iv. 2. r. iv. 2. 9. 
Herrings, red, iii. 3. 1. 4. 
Honey, iii. 3, 3. 3. iii. 3. 5. 1, 
Hop in beer, why noxious, iv. 2. 3. 6. 
iv. 2. 11 2. 
Hordeum diflichon, iii. 3. 3. 3. 
Humulus lupulus, iv 2. 3. iv. 2. 11. 
Hydrargyrus vitriolatus, v. 2. 3. 
Hyfteric difeafe, vi. 2. 1. 
pains, vi. 2. 1. 
convulfions, vi. 2. 1. 
I. 
Jalapium, iii. 3. 5. 5. 
Japan earth, iv. 3. 5. 2. 
Jaundice, iv. 2. 6. 3. 
Ileus, vi. 2. J,. 
Jncitantia, ii. 
Intermittents. Set Agues. 
Inverted motions, vi. 2. 1. 
in hyfteric difeafe, 
vi. 2. 1. 
of the ftomach, vi . 
2. 2. 
inteflinal ca- 
nal, vi. 2.5. 
of lymphatics,vi. 2.3 . 
Inula helcnium, iii. 3. 3. 2. 
Ipecacuanha, v. 2. 1. 
Iren, ruft of, iv. 3 6. 
Irritability prevented, iv. 2. 3. 3. 
Itch, iv. 21. 3. 
Inflammation of the bowels, v. 2. 2. 2 . 
L. 
Laurus campbora, iii. 3. 1. 
cinnamomum, iii. 3. 1. 
fafiafras, iii. 3. 1. 
Lead, iv. 3. 6, 
colic from, v. 2. 2. 2. 
fugar of, iv, 2. 9. 
Leeks, iii. 3. 3 r. 
Legs, ulcers of, iv. 2. 10. 
fwelled, iv. 2. 3. 8. 
Lemon-juicc, iv. 2.1, iv. 2. 2. 
Leontodon taraxacum, iv. 3. 4. 
Life flrortened by great ftimulus, i. I. 
Lime, i. 2.4 3. 
Liquorice, iii. 3. 3. 3. 
Liver inflamed, iv. 2. 6. 
Logwood, iv. 3.5. 2. 
Lymphatics, inverted motions of,v.2.r. 
M. 
Manganefc, ii. 2 4. 
Magnefla alba, iii. 3. 5. 3, 
Malt, i. 2. 3.5. 
Manna, iii 3.. 5. 
Marfh-mailows, iii. 3. 3. 3. 
Marjoram, iii. 3. 9. 
Marum, iii. 3. 9. 
Maftich, iii, 3. 2. iii. 3. 3. 
Menianthes trifoliata, iv. 3. 3. 
Mcnifpermum cocculus,ii. 3. r. 
Menftruation promoted, iv. 2. 6, 6. 
reprefied, iv. 2. 6. 6. 
Mercury, iii. 3. 2. vi. 2. 2. 
preparations of, iv. 3. 7. iv. 
2 7. iv. 2. 9 
injected a clyfler, vi 3.5. 
Metallic faits, iv. 2. 6. 
Milk, i. 2. 2. 
Mimofa nilotica, iii. 3. 3. 3. 
catechu, iv. 3. j. 2. 
Mint, INDEX OF THE ARTICLES.-Part III. 
95 
Mint, vi. 3. 3. 
Mortification, iv. 2. 9. 
Mucilage, vegetable, vii. 3. 3. 
Mucus, animal, vii. 3. 5. 
Mufhrooms, i. 2.1. 2. 
Mulk, vi. a. 1. vi. 3. 1. 
Muftard, iv. 3. 4. See Sinapifm. 
N. 
Naufea.in fevers, vii. a. J. 
Neutral faits diuretic, why, iii. 2. 4. 
increafe fome coughs, iii. 2. 4. 
increafe heat of urine, iii. 2. 4. 
Nicotiana tabacum, iii. 3. 9. ii. 3. I. 
Nitre, iii. 3. 4. v. 2. 4. 
Nutmeg, iii. 2. 1. 
Nutrientia, i. 
O. 
Oil of almonds, iii. 3. 5. 4. 
in cream, i. 2. 3. 2. 
of amber, vi. 2.1. 
exprefled, externally, iii. 2. 3, 
eflential, ii. 2. 3. iii. 3. 2. 
Oiled filk, vii. 3. 13. 
Oleum animale, vi. 2. 1. vi. 3. 4. 
ricini, iii. 3. 5. 4. 
Onions, iii. 3. 3. 
Opium, ii. 2.1. 2. iv. 1. 2. 
in nervous pains, ii. 2. 1. 5. 
in inflammatory pains, ii. 2.1.6. 
increafes all fecretions and ab- 
forptions, ii. 2. I. 1. 
abforption after evacuation, 
iv. 2. 8. 2. ii. 2. 1. 3. 
flops fweats, iv. 2. 1.2. 
intoxicates, ii. 2.1.1. 
Oranges, their peel, iv. 3. 3. 
Orchis, vii. 3.3. 
Oxygen gas, ii. 2. 4. i. 2. 5. iii. 2. II. 
iv. 1.4. 
produces and heals ulcers, 
iv. 2. 7. 
P. 
Pains, periodic, cured by opium-; ii. 2.1. 
Papin's digefter, i. 2. 3. 5. 
Papaver fomniferum, ii. 3. 1. iv. 3. 2. 
See Opium. 
Pareira Brava, iii. 3. 4 4. 
Parfley, iii. 3.4. 
Pallions, ii. 2. 5. 
Pafturage, i. 2. 3. 7. 
Pepper, iii. 3. 1. 
Peripneumony,'iv. 2. 8. 2. 
Perfpiration in a morning, iii. 2.1. 
not an excrement, iii. 2.1. 
Peru, balfam of, iii. 3. 5. 4. 
Petechiae, iv. 2. 4. 2. 
Pimento, iii. 3. 1. 
Piper indicum, iii. 3. 1. 
Piftacia lentifeus, iii. 3. 2. 
Pix liquids, iii. 3. 2, 
Phofphorus, iii. 2. 6. 
Pl after-bandage, iv. a. IO. 
Pleurify, iv. 2. 8. 2. 
Polygala feneka, iii. 3. 3. 2, 
Poppy. See Papaver. 
Portland's powder noxious, why, iv. 2. 
11. 2. 
Potatoe-bread, i. 2. 3.4. 
Potentilla, iv. 3. 5. 
Powder of iron, iv. a. 6. 6. 
Prunes, iii. 3. 5. I. 
Prunus domeftica, iii. 3. 5. I. 
fpinofa, iv. 3. 1. 
lauro-cerafus, ii. 3. 1. 
Pulegium, vi. 3. 3. 
Pulfe, intermittent, relieved by arfenic, 
iv. a. 6. 
Pyrethrum, iii. 3. 2. 
Pyrus malus, vii. 
eydonia, iv. 3. 1. 
rr • 
Quanta, tv. a. a. 
Quince, iv. 3.1. 
Quinquefolium, iv. 3. 5. 
R. 
Ratifia, why deftrucftive, ii. 2. I. 
Reaction, iv. 1. 10. 
Refin diuretic, iii. a. 4. vi. 2. 4. 
Rhamnus catharticus, v. 3. 2. 
Rheumatifm, iv. a. 4. 5. iv. a. IO. a. 
Rheum pahnatum. See Rhubarb. 
Rhubarb, iii. 2. 1. iv. 2. 5.1, iii. 3. J. 5. 
caufes conftipation, why, iii. 
2. 1. I. 
Rice, vii. 
Rofes, iv. 3. 5. 
Rot in fhcep, iv. 2. 6. 
S. 
Sagapenum, vi, 3. 1. 
Sago, vii. 3. 
Salivation not neceflary, iv. a. 7. 
hyfteric, v. 2. 3. 
Salt, common, unwholefome, iii. 1. 12. 
muriatic, iii. 3. 1. 
in clyfters, iii. 2. 7. 
Salts, why diuretic, iii. 2. 4. 
neutral, iii. 3. 5. 3. iii. 2. 4. 
improper in coughs and gonor- 
rhoea, iii. 2. 4. 
Salt-fifli and fait meat increafe perfpi- 
ration, iii. 2. I. 
Saflafras, iii. 3. 1. 
Scammony, v. 2. 2. 
Scarcity, times of, i. 2. 3. 5. and 6. 
Scilla, maritima, v. 2. a. iv. 2. 3. iii. 3, 
3- v. a. 3. 
Scorbutic legs, iv. 2. 10. 
Scrofulous tumours, ii. 2. 4. iv. 2. 9. 
Sea-water, iii. 3. 5. 3. 
Secernentia, iii. 
Secretion 96 
INDEX OF THE ARTICLES.-Part III. 
Secretion of the bladder, iii. 2. 6. 
redlum, iii. 2. 7. 
fkin, iii. 2. 8. 
Seneka, iii. 3. 3. 2. 
Senna, iii. 3. 5. 5. 
Serpentaria verginiana, iii. 3. 1. 
Sialagogues, iii. 2. a. v. 2. 3. 
Simarouba, iv. 3. 5. 
Sinapi, iv. 3. 4. 
Sinapifms, vi. a. 2. iii. 2.8, 
Sifymbrium nallurtium, iv. 4. 
Sloes, iv. 2. 2. 
Snuff in head-ach,v. 2. 3. X. 
See errhines. 
Snuffs of candles, vi. 3. 4. 
Society, i. 2. 3. 7. 
Soot, vi. 3.4. 
Sorbentia, various kinds, iv. 2. I. 
Spafmodic dodlrine exploded, vii. 2. 3. 
Spermaceti, iii. 3. 3. 3. 
Spice, noxious, iii. r. 12. 
Spirit of wine noxious, ii. 2. I. 
Sponge, burnt, vi. 3. 4. 
Squill. See Scilla. 
Starch, i. 2. 3. t. 
from poifonous roots.i. 2. 3. 4. 
Steam, bath of, iv. 2. 3. 8. 
Steel, iv. a. 6. 1, 
forwards and rep: effes menflrua- 
tion, iv, 2. 6. 6. 
powder, iv. a. 6. 6. 
Stizolobium filiqua hirfuta, iii. 2. 7. 
vii. 3.11. 
Strychnos nux vomica, ii. 3. I. 
Sublimate of mercury, iv. 2. 7. iv. 2 9.. 
Sugar nourifhing, i. 2. 3. x. and 5. iii. 
3-3-3- 
formed after the death of the 
, plant, i. 2. 3. J. 
aperient, iii. 3. 5. r. 
Sulphur, iii. 3. 5. 4. 
Sweats in a morning, iii. 2. I. I. 
on waking, iii. 2. I. I. 
cold, v. 2. 5. 
flopped by opium, iv. 2. I. 2. 
T. 
Taenia, vermes. See Worms. 
Tamarinds, iii. 3. 5. 1. 
Tanfcy, tanacetum, iv. 3.3. 
Tar, iii. 3. 3. 
Tartar, cryflals of, iii. 3. 5.1. Clafs i. 
21 3* I3'. 
vitriolate, iii. 3. J. 3. 
emetic, v. 2. 1. v. 2. 2. 
Tea, vii. 2. I. 
Tears, iii. 2. 10. 
Tcflaceous powders, iv. 2. 2. 
'Tetradynamia, plants of, iv. 2. 4. 
Tindlure of digitalis, iv. 2. 3. 7. 
Tinea, herpes, iv. 2- 1. 4, 
Tobacco, ii. 3. 1. iii. 3. 9. iv. 2. 3. 8. 
injures digeflion, iii. 2. 2. 3, 
Tolu balfam, iii. 3. 3. 
Tonics, iv. 1. 10. 
Tormcntilla erefta, iv. 3. 5. 
Torpentia, vii. 
Tragacanth gum, iii. 3. 3. 3. 
Turpentine, vi. 2. 4. 
fpirit of, iii. 2. 6. 
Turpeth mineral, v. a. 3. 
Tuflilago farfara,iii. 3. 3. 3. 
U. 
Ulcers cured by bandage, iv. a. to. & 
fcrofulous, iv. 3.9. 
of the mouth, iv. 2. 2. 
cured by abforption, ii. a. I. 4 .. 
iv. a. 3. 5. iv. a. 7. 
Uva urfi, iv. 3. 5. 
V. 
Valerian, vi. 3. 3. 
Vegetable acids, iv. 2. 1. 
food, j. 2. r. a. 
Venereal ulcers, iv. a. 7. 
Venefedtion, vii. a.4. iv. 2. 8. 
diminifhes fecretions, vii. 
a. 4. 
increafes abforptions, vii. 
a. 4- 
Veratrum, v. 3. 2. 
Vibices, iv. a. 4 3. 
Vinegar, i v. a. I. 9 iv. 3. 4. 3. ii. 2.1. 9. 
Vitriol blue in agues, iv. a. 6. iv. a. 2. 
in ulcers, iv. 2. 9. 
white, iv. 3. 6. v. a. X. 
acid, of, iv. a. I. 
in fwcats, iv. I. 1. 
in fmall-pox, iv. 1. r. 
Volatile fait, vi. 3. 6. 
Vomiting, v. 2. 2. 
flopped by mercury, vi. a. 2. 
Vomits, iv. 2. 3.7. 
W. 
Warm-bath, ii. 2. 2. 1. 
faline, iv. a 3. 8. 
in diabetes, vi. 2. 4. 
Water, i. 2. 4. 
dilutes and lubricates, vii. 2. 2« 
cold, produces fweats, iii. a. I. 
iced, in ileus, vi. a. 5. 
creffes, iv. 3.4. 
Whey of milk, iii. 3. 5. 2. i. 2. 2. 2. 
Willow, bark, iv. a. 3. a. 
Wine, ii. 3. I. 
Worms, vii. 1, 2. iii. 2. 7. iv. 2. 6. 4, 
in fheep, iv. 2. 6. 4. 
Wounds cured by bandage, iv. 2.10. 2. 
Z. 
Zinc, vitriol of, v. 3. 1. 4 DIRECTIONS to the BINDER. 
i« Pleafe to place the Plate confifting of one red fpot, 
at Sed. HI. i. page 9. 
2. Confifting of one black fpot, at Sed. III. 3. 
3. page 12. 
3. Confifting of five concentric coloured circles, 
at bed. HL 3. 6. page 13. 
4. Confifting of one yellow circle furrounded 
by one blue one, at Sed. XL. 4. 2. 
page 451. 
5. Confifting of one yellow circle and two blue 
ones, at Sed. XL. 10. 3. page 462. 
6. -- Confifting of the word BANKS in blue on a 
yellow ground, at Sed. XL. 10. 5. 
page 465.