:mmm UNITED STATES OF AMERICA WASHINGTON, D. C GPO 16—67244-1 msaasmm HI A N INAUGURAL DISSERTATION PERSPIRATION; SUBMITTED TO THE EXAMINATION OF THE Rev. JOHN EWING, S. T. P. Provost, THE TRUSTEES and MEDICAL FACULTY, OF THE University of penn/ylvam'a, For the Degree of DOCTOR OF MEDICINE, ON THE Thirty.firft Day of Mat, 1800. By JAMES AG YEW, A.M. Of Princeton, New-Jerfeyj "Member of the Philadelphia Medical Society. *' Simple Anatomy is a mafs of dead matter—It is Phyfiology which infufes life into it." Rujh on Animal Life* Philadelphia: VX' PRINTED FOR MATHEW from the Prefsof D, HOG AN, N°. 51, South Tiir, oppofite the United States Bank. 1800. / T O JOHN MACLEAN, m. d. Profeffor of Mathematics and Natural Philofophy, IN THE COLLEGE OF NEW-JERSEY. SIR, JlOU will not, I hope, consider this dedication as a matter merely of form, or an at- tempt to annex your patronage to a performance which may little deserve it. My intentions, I flat- ter myself, proceed from a more disinterested mo- tive,-----Gratitude requires, that I should thus publicly acknowledge the many instructions I have received from you, as well in the character of a friend, as that of my constant preceptor* These, Sir, I shall ever gratefully remember\ and consider it as a duty I owe you, in future life to appear to have deserved them. JVith the highest resped for your talents, and sincerest wishes for your happiness, I have the honour to be your Pupil and Friend, JAMES AGNEtV. May %oth7 1800. O N PERSPIRATION. OUR fkins are frequently covered with a fluid, called fweat. It has alfo been de- termined, by experiments which have been long known, that a fluid of a watery nature, but in a form commonly invifible, is conftant- ly efcaping from our furface ; and by others of a more recent date, it appears, that fubftances which, when uncombined, retain, at all known temperatures, an serial form, are at the fame time emitted. Thefe are faid to be perfpired, the firfl by fenfible, and the two laft by infenfible perfpir- ation. They have been the fubjeft of much difcuf- fion among phyficians. Some have confidcred them as proceeding from a common fource; while others have fuppofed them produced by different means. Many have efleemed their B emiffion ( 6 ) emiffion as eminently effential to health, while a few, particularly of late, have regarded their retention as harmlefs, or at leaft of little con- fequence. In this differtation it is propofed, to inquire into the foundation and fupport of thefe dif- ferent opinions, and, if poflible, to decide be- tween them. That this may be done, it is firfl of all neceffary to be acquainted with the ftruc- ture of thofe parts of the body from which they are emitted. I. Of the external integuments. Thefe are the cuti le, rete mucofum, and cutis vera, to which may be added, the ad- ipofe or cellular membrane. ift. Of the cuticle. It is a thin, tranfparent and infenfible pellicle, clofely joined to and con- nected with the fkin. Its fubftance does not appear to be of a fibrous or vafcular texture ; but is uniformly continued and hard, in fome meafure analagous to the fubftance of which the nails are compofed. On its inner furface it appears fmooth and uniform, but on its outer it is cov- ered with a great number of lamina, connec- ted in fuch a manner as to give it a fquamous appearance. Its denfity differs in different parts of . ( 7 ) of the body. On the inner furface of the hands, the foles of the feet, and fuch parts as are ex- pofed to the attrition of other bodies, it is thick and hard; while on other parts, fuch as the cheeks and lips, it is exceedingly fine and tender. It adheres ftrongly to the (kin, but af- ter it has^ been macerated for fbme time, or flightly ^utrified, they may be eafily fepara- ted. During their feparation, a number of white filamentary proceffes may be feen paffing between them; but which adhere to the cu«- tide when the feparation is completed. Thefe fubftances are tubular, and correfpond to fmall pores or openings, which are diftin&ly vifible on the external furface of the cuticle, even by the naked eye, but more particularly by the affif- tance of a microfcope.—Different opinions have been entertained of its origin : Some have fup- pofed it is produced by the matter, exhaled, gradually hardening. Some, that it is the cx- panfion of the excretory veffels, which are ev- ery where fprcad on the furface of the fkin • and fome, that it is by that of the nervous pa. pilJse. But little is yet known of its true ori- gin : one thing, however, is certain, that when abraded and deftroyed, it is conftantly and quick- ly re-produced, $. Inx, ( 8 ) 2d. Immediately under, and adhering to the cuticle, is the rete mucofum ; which is a fub- ftance in general of a greyifh colour, and reti- cular or net-like form. It is compofed of the extreme branches of the capillary veffels, which, after perforating the fkin, are united and interwoven, forming mefhes like thofe of a net, from whence it appears to have derived part of its name. When macerated in water, or fufTered to putrify, it becomes of a foft, mucillaginous nature, feeming to be nothing more than inorganized matter, or mucus ; and hence, probably, the term mucofum. In the in- habitants of the torrid zone it is black, or of a darkifh colour ; but in Europeans it is more or lefs inclined to white. It is confidered as the caufe of the colour of the fkin. J>-fs not generally agreed from whence this fubftance is derived ; fome fuppofing it to be formed of a humour exfuding from the true fkin. But that it confifts of veffels continued from the vafcular fyftem, feems probable from the fa£t of blufhing; for the colour beneath the cuticle at this time, is too general and dif- fufed, to be attributed to veffels leCs minute and extenfive than thofe forming the rete mu- cofum. Were not this vafcular, but imper- vious to the blood, by intervening between the cuticle and the veffels which convey the blood, it ( 9 ) it would* from its colour, prevent the red from being feen. The vafcularity of the fete mucofum, has been demonflrated lately by the injections of Mr. Baynham of London. In in- flammation alfo, a reticular texture of veffels is to be obferved on the furface of the fkin. And although neither of thefe fadts prove " thefe " veffels, in a natural ftate, to contain blood ;" yet the force of circulation at fome times may be fo great, as to force into ferous veffels a quantity of red (globules, and thus by affecting the veffels under confederation, occafiori that fednefs which we obferve in blufhing and in inflammation. 3. The cutis is the moft interior of what are properly termed the external integuments. It is contained immediately within the cuticle and rete mucofum, and is feparated from the muf- cles by the fat and cellular membrane. It is itrong and flexible, eafily admitting of exten- fion in the various flexions of the body and limbs. It feems to be compofed of numerous fibres, running in different directions. This tex- ture is particularly obfervable in leather, and feems to form the body of the fkin. It is cover- ed on its exterior furface by little eminences, which appear like fmall granulations, and are termed papillss. Thefe are confidered as be- ing made up of the terminations of nervous fila- ments, ( «° ) mentSj together with thofe of fmall arteries and lymphatic veffels. They have been de- fcribed as of different figures in different parts. Thofe on the foles of the feet, and in the hands, are moft obfervable, being higher and more clofely united ; they appear to be difpof- ed in rows, forming lines either of a ftrait, curved or irregular form, as on the ends of the fingers and toes. The fkin is plentifully fup- plied by arteries and veins, which every where perforate and ramify through,its fubftance, as has been fully demonftrated by anatomilts, by many fine injections. The arteries 'terminate here in very minute veffels, which have beerj called the cutaneous capillaries. Thefe, after numerous ramifications, unite with their cor- refponding veins at angles, more or lefs acute, from which proceed veffels called exhalants, as is proved by injections. And this appears tq have been the opinion of Haller, when he ob- ferves, that the cutaneous difcharge is fecreted, " ex arteriis exhalantibus, quae nullo mediq " folliculo ex rubris arteriis nafcuntur. In va- " fis perfpirationem cutaneam fundentibus in- " jeCtio aquea vel glutinofa tenuior ex ar- " teriis ita exfudat, ut nullum dubium fuper- ) every folid, as well as every fluid which com*- ^pofethe animal body, is derived, to it muft thefe and every fecretion be attributed. In it are con- tained all the principles of which the perfpira- ble matter has been difcovered to confift : * Quicogitavit in fanguine reperiri ferum co- * " agulabile," fays Haller, " aquanl exhalantem, " mucidum aliquod vifcidum, oleum denique, " incipiet percipere, potuiffe omnino fieri, ut " hujufmodi liquores, ex fanguine fepararentur " ut qui principia fua in maffa fanguinea ha- " beant." In order then to underftand the production of the perfpirable fluids, it is necef- fary to take into confideration the circulation of the blood, and its confequent diftribution into the different veffels capacitated to receive it. The heart being endued with the principle of irritability, contracts when irritated by the blood, and forces it into the arteries ; and thefe being poffeffed of the power of contractility, derived partly from their elafticity, and partly from their mufcularity, re-aCt on the blood, which, meeting with the leaft refiftance, muft pais towards their extremities. By thefe means, the blood is continued in its progrefs, till its return by the veins. But it muft have anfwered its particular purpofe in the circula- tion before its return to the heart. Every part E muft * Prim. lin. par, 193. ( 3° ) muft be fupplied with its proper nouriflimcnt, every gland with the matter fit to form its Secretion, every furface lubricated with its proper fluid, and the unneceffary and feculent portions feparated. If the exhalants aredireCt- ly continued from the arteries, they muft par- ticipate in their aCtion, and muft receive fuch parts of the blood, as can be forced into them by their contraction. The diameters of thefe veffels being too fmall to admit the red blood,. if the aCtion of the heart and arteries be mode- rate, the fluid propelled into them will be the thinner part of the blood, as the aqueous, and a portion of the faline parts of the ferum, to- gether with fuch particles as are capable of re- ceiving an aerial form, and may be neceffary to fee eliminated from the fyltem. Part of the fluid which is thus emitted, will be fucked up by the abforbent veffels, which arife from the furface, part of it will be imbi- bed by the clothes, where they are applied to the body ; part of it will be diffolved by the air, from fuch parts as it comes in eontaCt with* part of it will be diffolved in the gaffes that are emitted; and if the quantity difcharged fhould be greater than what the abSorbents can Suck up, and the aeriform fluids* diffolve, then will an accumulation of it take place in fuch parts as are not touched by the clothes, or to which the air ( V ) air has no accefs, as frequently happens, between the toes and other receffes of the body. But when the force of circulation is greater, more fluids will be forced into the exhalants, and thus the quantity of perfpired matter will be increafed. If it be more than the caufes al- ready affign ed for its removal can diffipate, it ■Will remain in a vifible form on the fkin. Thus, then, the infenfibly perfpired watery fluid, is that which is diffolved by the air and the gaf- fes emitted from the fkin ; while the Sweat is the feline, oily of mucous parts which remain, un- abSorbed, or is imbibed by the clothes. On this principle, we can account for the ap- pearance of fweat from the operation of internal ftimuli, or from exercife. For by increafing the rapidity of circulation, the fucceffive portions of fluid are more frequently brought to the fur- face, and difcharged. In the fame manner we can explain the pro- fufe fweats, which fucceed the hot fit of fevers, particularly thofe of the intermittent type. In the coldftage, the blood leaves the cutaneous vef- fels, retiring towards the inner parts of the body, as appears by the palenefs and fhrinking of the mufcles of the face, thefhriveling of the fkin, and the drying up-of ulcers.* It therefore, collects in * Cullen's Firft Lines, f 32 ) in unufual qi aitity about the heart and the vef- fcls in its neighbourhood. The heart being thus preternaturally diflended, contracts with greater force, and propels the blood again to- wards the Surface of the body ; but the veffels of that part having, by the previous receflion of the blood, loft an accuftomed ftimulus, become more irritable, fo that when the blood is again driven towards them, their fides are excited to contract, become more denfe, and their diame- ters are leffened ; nay, perhaps, they may be rendered quite impervious ; and thus they af- ford one obftacle to the paffage of the blood in- to them. But the force of the heart and arte- ries being greater than this refiftance, they, through repeated exertions, dilate the cutaneous veffels, a certain ring or portion of the artery being diflended by each fucceeding impulfe, un- til at length they are filled with more than their ufual quantity, and pour out a preternatural quantity of fweat. And this will continue un- til the violent aCtion of the heart and arteries becomes leffened, from the ftimulus which cauf- cd it ceafing equally to excite it. Hence, the quantity of fluid difcharged will gradually be- come lefs, and will at laft difappear. As the fweat continues to flow, the heat of the body, from the conftant evaporation which takes place, will be gradually diminifhcd, and will at Jaft re- turn to its ufual temperature, I am ( -33 ) I am aware, that other explanations have been offered for the appearance of fweat in fevers. But this appears to me the moft fatisfaCtory. * Dr. Darwin afferts, that the perfpirable mat- ter is fecreted in as great quantity, during the hot fit as afterwards, when the fweat is ob- ferved on the fkin ; but that during this itage, the cutaneous abforbents aCting with greater energy, and the exhalation being augmented by theincreafed temperature of the fkin, the fluid does not remain on the furface, but is in part re-abforbed, and in part diffipated in the air. And he afcribes the after appearance of fweat, to the aCtion of the abforbent veffels being lef- fened by the application of cool air, or cold bed clothes. The doCtor, however, has taken for grant- ed what has not any where been demonftra- ted. f " The heat in fevers," fays he, " ari- " fes from the increafe of fome fecretion." Hence the increafe of perfpiration, which by him is confidered a fecretion, produces an in- creafe of heat; for increafed fecretion " is al- " ways attended with an increafe of local, or " general heat." But as the temperature of the Secretions has never, by any experiment, been ascertained, this affertion cannot be ad- mitted, * Zoonom. part ii, pag. 20. flbid. pag. 19. ( 34 ) mitted. Chemical changes are, to be furc, al- ways attended with a change of temperature ; but it does not follow, that it muft be an in- creafe of temperature; for they are certainly Sometimes followed by a diminution of tem- perature. The principle, then, that the heat of the fkin irt fever depends on increafed per- fpiration, is without foundation. On the con- trary, the heat muft be diminifhed by perfpira- tion, for a great part will, as he has fuppofed, be carried off by the air ; and the folution of a- ny fluid in air is attended with a diminution of temperature. Nor can the non-appearance of fweat in the hot ftage, be attributed to the greater abforption from the fkin ; for although it be admitted, that the aCtion of the abforb- ents is increafed in proportion to that of the Secerning Syltem, yet the abSorption will be pre- vented, as may be fhewn from his own princi- ples. For " when the fanguiferOus fyftem is " full of blood, the abforbents cannot aCt fo " powerfully, as the progrefs of their contents " will be oppofed by the previous fulnefs of " the blood veffels.'* If fweat, therefore, were to take place during the hot fit, while the vef- fels of the fkin are uriufually diftended, as ap- pears from the great fulnefs and turgefcence of every external part, as it cduld not be re^ admitted through the abforbents, and part of it ( 35 ) it only being diffolved by the air, it would ea^ lily be obferved. The opinion, that fweat becomes vifible in confequence of the diminution of temperature, which before prevented it, is further rendered improbable, by perfons frequently paffing from the hot to the fweating ftage, without being cxpofed to cooler air, or a change of bed clothes. The faCt derived from Mr. Alexan- der's experiments, viz. that Sweat does not appear until the heat of the fkin has fallen from 1120 to io$°, does not here apply. For from his experiments it appears, that when the temperature is increafed by the artificial application of external heat, beyond the boun- dary of health, fweating is prevented. In this cafe, from the power of the {timujus, the ca- pillaries are exceflively excited, and hence con- ftriCted, until, by the application of cold, an abftraCtion of heat takes place, and a confe- quent diminution of excitement, when the cu- taneous veffels become again dilated, and the fweat begins to flow. But in fever, the tem^ perature of the body never becomes fo excef- five, and the heat of the fkin never furpaffes fo far that of the internal parts; and as the heat of the fkin is derived from the conftant influx of the blood into its veffels, its temperature cannot be leffened before the commencement of perfpiration, ( 3«- ) perfpiration, as there is no other caufe of alter- ation. The explanation, therefore, before given, appears to me, the only proper or fatisfaCtory one that can be offered, of the " warm fweats," or thofe which Succeed fevers. On the fame principles are to be explained the profufe colliquative fweats, which take place in that exhaufted ftate of the fyftem, which precedes death, and is confequent on fe- vers of the continued form. In thefe the ac- tion of the Sanguiferous fyftem, together with the exceffive operation of heat, contribute finally to exhauft the extreme veffels, which from the debility thus induced, are no longer capable of permanent contraction, but become expanded, and permit the fluids, which are ftill continuing to be fent to them, to be difcharged on the fkin. But as the aCtion of the abforbents is, at the fame time, diminifhed with the re- fiftance of the capillaries, they will imbibe lefs than ufual ; and thus the fweat will be accu- mulated on the furface. As the heat of the body is diminifhed by the evaporation from its furface, and the accumu- lation of it prevented by the inaCtion of the veffels ; the Sweat which ftands on the Surface, will ( S7 ) will convey to a perfon the fenfation of cold. The viScidity of fweats in fuch cafes, may be owing to the watery part being diffipated in the air, while the oily and coagulable parts remain unabforbed ; perhaps alfo fome other parts will be difcharged, from the little refiftance of the exhaufted capillaries. A different opinion refpeCting cold fweats, has been offered by Dr. Darwin, who calls to the aid of his theory, his favorite hypothefis, the retrograde aCtion of the abforbents. But upon examination, it will be found, that his theory on this fubjeCt, as well as the principle on which it depends, are more ingenious than true. The lymphatics are univerfally known to anatomifts, to be fupplied, at very minute diftanees, with valves, which, from their fituation, muft be intended to prevent the regurgitation of their contents. This cannot, therefore, take place, unlefs the fluid be driven back with fuch vio- lence as to force or tear the valves. But in order to get over this difficulty, he obferves, that, *" as thefe valves are placed in veffels " which are endued with life, and are them- " felves endued with life alfo ; and are very " irritable into thofe natural motions, which " abforb or propel the fluids they contain, it F u is * Zoonom. part i. fefl* 29. 2, ( 38 ) " is poflible, in fome difcafes, when thefe " valves or veffels are ftimulated into unnatural " exertions, or are become paralytic, that du- " ring the diaftole of the part of the veffel to " which the valve is attached, the valve may " not fo completely clofe, as to prevent the " relapfe of the lymph or chyle." And he adds, that this is rendered probable, by injections of mercury, water, Sec. eafily palling the valves, contrary to the natural direction of the fluids. That thefe veffels, as well as their valves, are endued with life, will not be doubted ; but that they are poffeffed of that degree of aCtion which he feems to afcribe to them, is, I believe, not allowed by all. Some have attributed their power of abforption to capillary attraction ; but whether their functions as veffels arc to be referred to this, or to a contractile power in- herent in them, has not yet been fufficiently as- certained. But admitting them topoffefs a na- tural capacity for action, it is fcarcely probable that their action could become fo exceffive. And fuppofing the ftrength of the valves pro- portioned to that of the veffels, as they are known to be exceedingly tender, an extravafa- tion would feem as apt to take place as a regur- gitation. That this fhould be caufed by a paraly- fis of the veffels, appears ftill more improbable ; for as in this cafe, the veffels are unable to act, to fuppofe a return of the fluid from this fource, would ( 39 ) would be admitting an effect without a caufe. The doctor has alfo made ufe of feveral analo- gies with other veffels, to prove the point in queftion, but they do not feem ftrictly to apply. Hehasfuppofed it from the regurgitations of the contents of the ftomach and lacrymal fack, and the receflion of the blood in the capillary vef- fels. But the analogy here cannot be admitted ; for the ftomach, although its orifices have gen- erally been faid to perform the offices of valves, cannot be confidered as poffeffing them. Befides, the number, ftrength, and rigidity of its muf- cular fibres, together with the functions which it is intended to perform, render it very diffimilar The lacrymal duCls and capillary veffels, have never been fuppofed to contain valves, and therefore will the more eafily permit a retro- grade motion of their fluids, when a caufe affects them. He has mentioned but one faCt, that would feem to ftrengthen, in any degree, his theory. He * u tied the neck and ureters of a " frefh ox's bladder, and made an opening at *' the fundus of it ; then having turned it in- " fide outwards, filled it half full with water, " and was furprifed to fee it empty itfelf fo " haftily." But no proof, in my opinion, is de- rived from this experiment, for although the bladder was found to empty itfelf, it does not follow * Zoonorn. part i. feci. 29. 2, n 4° ) follow it did fo by the paffage of the water through the lymphatics. The bladder is plen- tifully fupplied with blood veffels, which alfo pafs on to it, from its neck, and by their fepara- tion with the bladder from the body, will afford as Speedy a pafTage as the one fuppofed. If a lymphatic be compreffed, by the aCtion of mufcles or the preffure of any body external, the contained fluid retiring from the force, will efcape at that part where it meets the leaft re- Jiftance, and will confequently be forwarded to- wards its deftination. The idea, then, of the regurgitation oftheabforbed fluids, feems merely fanciful, and the explanation of any effufion from this caufe entirely unfounded. 2d. The origin of the aeriform fubftances per- fpired, cannot fo eafily be afcertained. The ex- periments on this fubject have only difcovered the quality of the air emitted ; its fource remains yet for further inveftigation. We know, how- ever, that the blood is conftantly undergoing a change in the lungs, by a particularproccfs which takes place there, probably fimilar to combuftion. Carbonic gas, in this cafe, is emitted from the lungs, whether formed there or exifting in the blood. The latter opinion is embraced by fome, though the former is moll generally adopted. I may venture, however, on an hypothefis, that, as ( 4* ) as the union of oxygen is believed, its combina- tion with carbone in the blood may be the origin of the gas that is emitted from the fkin. The ex- iftence of azot, in the blood, and moft animal fub- ftances, has been demonftrated by numerous ex- periments ; but in what manner, or by what pro* ccfs, its feparation is produced, muft be left for future facts to determine. Little, therefore, can at prefent be with certainty faid, as to the ori- gin of the aerial difcharge. V. Having now confidered the qualities, as well as the quantity and production of the mat- ters which conftitute the perfpirable difcharge, as far as could be afcertained from the experi- ments and faCts related by different writers, I fhall next proceed to the confideration of the queftion, Whether the retention of the perfpi- rable matter, is ever productive of derangement in the fyftem ? Sweat, before the knowledge of the infenfi- ble difcharge, was confidered by the humoral pathologifts, as an excrementitious fluid, ne- ceffarily fecerned from the fyftem, and produc- tive of difagreeable and dangerous confequences, if retained in it. That this, even in the in- fancy of the medical art, was confidered as a caufe of difeafe, appears from an aphorifm of Hippocrates : " Ubi in corpore fudor, ibi mor- " bus." ( 42 ) " bus." The moft natural inference we could draw from this fentence, would be his belief in the retention of the perfpirable matter as inju- rious to the health of the body ; for its prefence in a part he confiders a fymptom of difeafe. The idea of morbific matter, as produced by a putre- factive fermentation in the blood, together with the fetid odour given out by fweat, in fome difeafes, led, probably, to the belief of its ef- cape through this channel, as the moft natural for its elimination from the fyftem. To a fup- preflion of perfpiration then, were moft difor- ders of the human body attributed. Morbific matter, by being retained, was carried back into the blood veffels, producing general affec- tions, or by being confined to a part, gave ori- gin to many local diforders. Hence proceed- ed eryfipelas, herpes, and the feveral affections of the lungs and trahea. Dr. Darwin, however, and feveral who have embraced his opinions, have rejected the notion of the fuppreffion of this difcharge having any fhare in the production or crifis of difeafes. He has endeavoured to fhew, from the practices among many nations of anointing with oil,* of the fafhion of painting, and the ufe of powder and pomatum among ourfelves, that perfpira- tion * Zoonom. part ii. pag. 24. ( 43 ) tion may be checked without injury. This may be, in a great meafure, true ; but the ufe of oil, and the other fubftances with which the body is fometimes fmeared, does not en- tirely prevent the difcharge of perfpirable mat- ter ; for on increafed exercife, the pores, tho' covered, are forced frequently by a copious flow of fweat. Were this not the cafe, the pofition would be in a greater degree efta- bliflied. The operation of cold on the body, in pro- ducing difeafe, has been entirely attributed to the change produced in the living fibres,* and not to an obftruCtion of perfpiration. This effeCt of cold will immediately be granted ; but ftill the obftruCtion may have a confider- able fhare in the operation. For by leffening the evacuation, a quantity of fluid will be re- tained, which quantity will be greater in pro- portion to the increafe of exercife or temper- ature. This, therefore, will be an addition- al ftimulus to thofe which are afterwards applied, and will confequently affift in throwing the fyftem into violent aCtion, which, by its force, will overcome the refiftance of the cuta- neous veffels, which, from their previous qui- eScence, and the preSent ftimulus, muft be ex- ceffively » Med. Repof. Vol. ii. No. i. Art. 13. ( 44 ) ceflively excited ; or by exciting Sever, call for evacuations of a different kind. It is af- Serted, however, that the diminution of this is followed by the increafe of another difcharge. This will generally be admitted, but the in- creafed evacuation is not always fufficient to counterbalance that which is checked; yet if it was, another part being obliged to make a greater exertion than that for which it was naturally deftined, will neceffarily be injured, and the greater and more permanent will that injury be, the greater the fenfibility of the organ affected, and the longer the contin- uance of the caufe which produced it. Thus, the inteftines will fuffer more than the kidneys, and the ftomach more than the intef- tines. If the part affected be very important, the whole conftitution will be proportionably deranged. As, for inftance, fuch an affection will injure digeftion, and hence, dySpepfia and the diSeaSes conSequent on an imperfection in this function. An affection of the inteftines will give rife to colic, diarrhoea, cholera and dy- fentery. Thefe difeafes may frequently be re- ferred to a determination to the bowels from fuppreffed perfpiration. With the effects of a fuppreffed perfpiration, in producing catarrh, we are fufficiently ac- quainted. That it is checked during the in- flammatory ( 45 ) flammatory fymptoms of this affection, I think evident from what has been already faid of it in the hot ftage of fevers, and tho' the other parts of the body fhould be obferved to perfpire, the exceffive aCtion in the part affeCted, would pre- vent its appearance there. The conclufion I Shall therefore confider juft, that the regular operations of this function can- not be arrefted very fuddenly, without creating fome derangement. I fhall now clofe the differ- tation, without enlarging on what has been faid, or attempting to explain the operation of thofe articles, the effects of which, as fudorifics, muft be known to all. .----------Si quid not'ijii reflius iftit Candidus imperii.---- horat. And now, before I take leave of the fubjeCt entirely, I would wifh the Profeffors to accept my fincere thanks for the inftruCtions I have received from their leCtures, and the many op- portunities of improvement I have experienced thro' them, while a ftudent in this Univerfity, To Dr. Wiftar I am particularly indebted, for the obiervations and inftruCtions with which he has favoured me, both on this and numerous o- ther fubjeCts, and for feveral valuable cafes in his private practice of furgery, with the infpec- G tion ( 46 ) tion and knowledge of which he was kind enough to indulge me. For thefe, and his polite attention to me during my refidence in this place, I beg he will accept my grateful ac- knowledgements, and be allured of my faithful remembrance. FINIS.