UNITED STATES OF AMERICA WASHINGTON, D. C. GPO 16—67244-1 aggBg^rgg; a > ■ "^w^ *. A DISSERTATION ON THE PROXIMATE CAUSE OF INFLAMMATION, WITH AN ATTEMPT TO ESTABLISH A RATIONAL PLAN OF CURE. Submitted to the examination of John Andrews, D. D. Provost, the Trus« tees, and Medical Professors of the University of Pennsylvania, on the twenty-fifth of April, 1811. X t\iBS^V'>^ r ^—^'-W^ FOR THE DEGREE OP DOCTOR OF MEDICIIE. ' ^S. '{ f ~'yj\. BY ALEXANDER II. STEVENS, A. J^^^^p- OF NEW-YORK. Honorary member of the Medical Society of Philadelphia, and member of the Philomedicul Society of New-York. Medicos et Philosophus in omnibus qux circa corpus hnmanum evcniunt ranta- tionibus, ex claii6 principiis veras conclusiones et connectiones conficere et elicere debet. Fred. Itoffm. Principles in Medicine are the only safe and certain guide to successful practice liiuh. PHILADELPHIA: FEINTED FOR THE AUTHOR BY J. MAXWELL. 1811. / TO EDWARD MILLER, M. D. Professor of the practice of Physic and Clinical Medicine in the College of Physieians and Surgeons of the Uni- versity of the State of New-York, and, TO BENJAMIN RUSH, M. D. Professor of the Institutes and Practice of Medicine in the University of Pennsylvania, This Dissertation is respectfully dedicated, in testimony of their acknowledged talents and worth, as well as of the grateful sense of their kindness to their friend and pupil, THE ATJTHOB. PREFACE. The publication of an inaugural dissertation not being now required by the laws of the University of Pennsylvania, and being withal so uncommon, seems to indicate, on the part of the author, either a degree of vanity to see his writings in print, or a presumption that they contain something worthy of public inspection. The author of the following sheets is well aware of these re- flections. He has, notwithstanding, ventured to appear before the public, not from any confidence he had in his own judgment, but in compliance with the advice of two of his medical preceptors, who have been pleased to say that the facts stated by him are important; and lead to useful practical results in medicine. A DISSERTATION, &c. Mankind have ever been prone to extremes. Froin- the earliest periods in the records of Medicine, we find them vibrating between the highest degree of empiri- cism and the total disregard of experience. To avoid equally each of these errors, to apply in unison with each other, the external and internal senses to the advance- ment of the most noble of all arts, constitutes one of the most dignified employments of which we are capable. If the following observations should add to the stock of our correct notions on the subject of the proximate cause of inflammation, I shall be amply rewarded by the consciousness of their utility; if, other- wise, it will still not be thought amiss, that a candidate for Medical honours should proffer to his respected Alma Mater these first fruits of his labour, in this too little cultivated field. In medicine, as in all other sciences, there are a few great principles which are the cardinal points of its appli- cation to the arts depending upon it. One of the most important of these, is the doctrine of inflammation. s Hippocrates has justly said, that the treatment of acute diseases shows most perfectly the skill of the physician. The greater portion of these are febrile diseases, some of which are entirely dependent upon, and all intimately connected with topical inflammation. Inflammation is the element of the most dangerous diseases. It is a morbid oxygen supporting a com- bustion which reduces us to ashes. Of this probably man first died, and who can promise himself to escape its dangerous influence? If such then be the frequency, and such the fatality of inflammatory diseases, it will, not be deemed uninte- resting to take a brief view of the doctrines which have prevailed with regard to the nature of inflammation: to point out its most usual seats, and to explain the anatomy of the parts connected with it—to mark the persons most obnoxious to its influence, and the circum- stances which occasion its attacks—to notice more mi- nutely the various symptoms which attend it in all its stages and modifications, and briefly to mention some of the agents which aggravate or abate them. If, in this general view of the subject, the exist- ence of one common cause be shown to be necessarily connected with the phenomena which take place—if a succession of effects be perceived which can be traced to such common cause, no one will hesitate to believe that this is the essence of inflammation; nor can it be doubted that a rational plan of cure, founded upon well established theory, will be an object of highly import- ant application to therapeutics. 9 The method of induction is conceived to be better adapted to the discovery of medical truth, than the ana- lysis which leads to numerical certainty. Medicine can- not boast of those axioms which support the super- structure of the mathematician. The industry of its cultivators, is best exercised in comparing facts, de- rived from observation, and drawing probable infer- ences from collateral circumstances. The most invariable symptoms of inflammation as commonly laid down, are * heat, swelling, redness and pain. In the course of this essay I shall endeavour to prove, that swelling, heat and redness are not the constant attendants of inflammation; but that the highest grade of it is accompanied by coldness, paleness and diminution of bulk, and that such symptoms occur in every in- flamed part. Inflammation has been defined to be an increased de- termination of blood to a part, accompanied by a morbid action of the vessels. How far this definition is cor- rect, we shall have occasion to notice hereafter. The most ancient idea of inflammation was that of a combustion. This we know from the writings of the Greeks, (and what is more, from their language, which is older than their writings,) to have been their opinion. From the conceived analogy between inflammation and burning, it is probable they first expressed both by the same term, ^Aey^ov; though (pteypamv its derivative, was limited to the expression of the action of burning. Hippocrates seems scarcely to have passed the threshold of inquiry into the causes of inflammation. * Signa vero inflammations sunt quaLuor ; calor et tumor, cum rubore et dolore. Ceh. Edit, a Targae ft. 22. B 10 From a remark* which he has made in his book De Capitis Vulneribus, it would seem, that he considered it merely an increased flow of blood into any part. Some of his followers, however, refining upon the notions of their master, held that inflammation arose not only from an excessive flow of blood, but of every sharp, gluti- nous and pituitous humour; to which imaginary agents they chose to assign the production of its differ- ent varieties. Erisistratus, a man no less remarkable for the antiquity of his writings, than for his peculiar fdoc- trine of fever, supposed that inflammation was owing to the J escape of the blood from its proper vessels, into those destined to contain the animal spirits: for such was supposed, in his time, and for a long period after, to be the function of the arteries. Rapidly passing over these vague hypothesis, which deserve little notice, but as showing the range which the human imagination will take, when unguided by judgment, I proceed to the climacteric of extrava- * Partes ulcus ambientes inflammantur ac intumescunt ftrojiter sanguinis influxionem. Hip. de Capitis Vulneribus. t Quo magis erravit Erisistratus qui febrem nullam sine hac esse dixit.—Cels. a Targae fi. 118—119. This doctrine has lately been revived by Messrs. Wilson, Clutterbuck and others. % Alia sanguinis in eas venas quae spiritui accommodatae sunt, transfunditur et inflammationem quam Graeci phlegmonem vocant excitat, eaque talem motum efficit qualis in febre est: ut Erisistrato placuit Cels. ut antea. 11 gance, the opinion held by * Galen and his fol- lowers. t" When an unusual quantity of hot blood is driven into any part of an animal, the large vessels are forth- with distended, and these becoming incapable of con- taining more, it then passes into those which are smaller. When the smaller vessels are full, it is transuded into the interstices of the neighbouring flesh, and putrifying there produces morbid heat.'' But the chimeras of Ga- len do not terminate here. This " master spirit," con- jures up a host of humours into existence, to " Do his bidding and abide his will;" which, like so many malicious demons, preside over the various forms of inflammation, and perform the several duties assigned to them, in this pathological phantasma- goria. The production of exquisite phlegmon was as- signed to pure hot blood. Bile waved his wand, and the fiery Erypelas appeared: the bloated form of Edema slowly arose at the incantation of Pituita. As these effects were slowly, or suddenly produced in any part, a defluxion, or a congestion as the case might be, was the consequence. According to this hypothesis, the indication of cure was to produce a revulsion, or deriva- tion, as the case might be, of the peccant humour to which the disease was attributed. The discovery of the circulation of the blood, by the immortal Harvey, banished these fanciful doctrines. As derivation and revulsion were shown to be incompatible with the quick motion of the blood, in the round of circulation, so the *Galeni Opera omnia:—passim + Buserius 12 office of preparing and propelling it, assigned to the li- ver, was found to be irreconcilable with the true func- tion of the heart. From the noxious influence of fermentation, which alchemy strangely transferred from the alembic to the vascular system, medical opinion next sought refuge in the Hydraulic Machine of Boerhaave. The Anima Medica ancj Archaus of Stahl and Van Helmont, and the Vis Medicatrix of Hoffman, did not en- joy their full share of importance until the time of Cul- len. There is not the least reason to believe that any thing like fermentation does take place in the blood of a living animal. Indeed, it is absolutely inconceivable that it ever can; when it is considered, that the blood is a vital fluid, circulating constantly, in a healthy animal, through every part of the body, and forming living parts; and that the least extraneous matter introduced into the san- guiferous system, (and such we may see Sydenham re- fers to, as causing topical inflammation,*) has invariably proved a cause of instant death; or of such violent symp- toms, as plainly to demonstrate that any considerable in- testine motion of the blood, in which its integrant par- ticles acted upon each other, or were acted upon che- mically, by foreign matter, was entirely incompatible with life. * Now, though a pleurisy proceed from a peculiar and speci- fic inflammation of the blood, yet it sometimes succeeds fevers of Avhatsoever kind they be: occasioned by the sudden transla- tion of febrile matter to the pleura or intercostal muscles." Rush's Sydcnhnm,p. 177. 13 Boerhaave, who possessed all the learning of the age in which he lived, and which is particularly distinguished for the cultivation of mathematical knowledge, employ- ed his talents in the formation of a theory of inflamma- tion, more specious than any which had hitherto been of- fered. Leeuwenhoek, some time before, imagined that he had discovered six series of globules, each fitted, in the healthy state of a part, to be transmitted through as many corresponding series of vessels. Upon these experiments, Boerhaave founded his theory of inflamma- tion. Whenever one of these series of globules enter- ed one of the vessels, destined only to transmit those of the series next below it in magnitude, it produced what he called an error loci and obstruction, which by irri- tating the heart and large arteries, caused in them that increase of action, which is evident in all inflammatory diseases. As he supposed the area of the heart to be greater than the sum of the areas of all the vessels carrying blood from it, the effect of this obstruction was believed to be, an increased velocity of the blood, in the arteries not obstructed. This indeed, would necessarily take place, if the heart discharged the same quantity of blood in a given time. A lentor, or too great spissitude of the blood, was another cause of obstruction allowed by Boerhaave. But from whatever source obstruction arose, to the course of the blood in its passage from the heart, the contraction of this viscus was rendered more powerful, by the in- creased difficulty with which it discharged this fluid into the aorta, and pulmonary vessels. Boerhaave ex- 14 plained the morbid heat of inflamed parts, by the sup- posed evolution of caloric, occasioned by the increased attrition of the globules against each other. This hypothesis is evidently too mechanical. It overlooks entirely the operation of .the vital principle, and the change of what has since been called the solidum vivum. It does not account for many of the most im- portant symptoms of inflammation; neither does it embrace most of its causes. Attrition of fluids does not produce heat. A blow can neither be a primary cause of morbid lentor of the blood, nor of error loci. All the different species of inflammation, too, accord- ing to this hypothesis, must, it is evident, be occasion- ed by some difference in the nature of the obstructing cause. But neither error loci, nor lentor, nor a combi- nation of these, in all their different degrees, and modifi- cations, furnishes a ground for the distinctions of the se- veral kinds of simple inflammation; much less does it af- ford any satisfactory account of specific inflammation; nor have we the least shadow of reason to believe the existence of a morbid lentor, in many cases of inflamma- tion. The gluten which rises to the surface of blood, drawn from patients labouring under inflammatory dis- eases, exists equally in that of the most healthy per- sons. But further, obstruction alone, cannot constitutethe essence of inflammation; because it often arises from anuerisms, and may at any time be artificially produced without inducing inflammation. The whole hypothe- sis is predicated upon the supposition that the area of the heart and arteries forms a truncated cone, of which 15 the heart is the base, and the arteries the section near- est the vertex. Precisely the reverse of this has been proved to be the case; inasmuch as the sum of the squares of the diameters of all the vessels proceeding from the heart, or from any arterial trunk exceeds the area of the heart, or vessel giving off branches*. Gorter, a pupil of Boerhaave, denied that obstruction did take place at all, and referred the phenomena of in- flammation to an increased iQ vital motion." This expla- nation differed only in the terms by which it was ex- pressed from the " tonic motion" of Stahl. Hoffman asserted that obstruction took place in con- sequence of spasmf- Further than this, it does not appear that he gives any explanation of the cause of in- flammation. He indeed, as well as his folloAver, Dr. Cullen, invokes the Vis Medicatrix Natures to assist him in explaining many of the attendant symptoms. But whether we give intelligence to this imaginary principle, or merely understand by it a physical neces- sity, it is equally evident in either case, that we are as much in the dark as ever. * Circles are to each other as the squares of their respective diameters. Euclid Lib. xii. t Inflammationis hujus proxima causa sanguinis vel etiam seri impuri in extremitatibus arteriolabus stasis est, qua sangui- fera per vesicae tunicas discurrentia vasa a sanguine copiosus congesto nimium replentur, distenduntur et nervosa exquisitis- simae scnsationis tunica, in vehementem sjiasmttm abripitur: ex quo reliquorum symptomatum origo. Hojfm. O/icr. Omn. I Ah. iv. r. ii 16 In the first place we are referred to an imaginary intelligent principle, existing in the body, independent of the soul, and occasioning all our diseases, and even death, by its ill directed efforts to preserve the body; and whose operation, reason, which was surely given us for our preservation, often directs us to oppose! In the second, we have what, perhaps, is better, as less likely to mislead, the simple expression of the fact. Dr. Cullen advocated in so plausible a manner this doctrine of inflammation, and brought it so much more into respect than it had ever been before his time, that his explanation may, perhaps, deserve a separate con- sideration. *" Some causes of inequality," says that celebrated physician, " in the distribution of the blood may throw an unusual quantity of it upon particular vessels to which it must necessarily prove a stimulus. But further, it is probable that to relieve the congestion, the Vis Medicatrix Natura increases still more the ac- tion of these vessels; and which as in all other febrile diseases, it effects by the formation of a spasm upon their extremities. A spasm of the extreme arteries, supporting an increased action in the course of them, may therefore be considered as the proximate cause of inflammation; at least in all cases not arising from di- rect stimuli applied; and even in this case the stimuli may be supposed to produce a spasm of the extreme vessels." 1 An inequality in the distribution of blood* may take place without inflammation. Now as ef- * Cullen's First Lines of the Practice of Physic. Sec. 244. r*t sequent. 17 fects must always uniformly follow their causes, ' an inequality in the distribution of the blood' must be considered, not of itself a cause of inflammation, as Dr. Cullen makes it, but as an effect either of inflam- mation, or a collateral effect of a common cause. As this forms the link which connects spasm with the explanation, it might be sufficient to show that Dr. Cullen had mistook an effect for a cause, in form- ing the groundwork of the hypothesis. But over- looking the error into which we are led by be- lieving, that a cause of disease exists only, after many of its symptoms have appeared; or that spasm, supposed to be the cause of inflammation,takes place to relieve con- gestion—mistaking the vis medicatrix naturae, for the power of an argument, to preserve the medical body corporate, from pathological scruples—we are puzzled to see how spasm can have the desired effect of re- lieving congestion. We fear lest, after a short examina- * tion before the tribunal of impartial reason, spasm be found an idle boy, quite unfit to execute the orders of the fickle dame that sent him. The causes of congestion are either an increased af- flux of blood to a part, or a slower transmission of it through its vessels. Whatever diminishes the one, or increases the other of these, relieves it. In what man- ner can a spasm of the cappillary vessels produce either of these effects? Diminishing or actually obli- terating the diameters of the small arteries, renders the transmission of blood more difficult;* nor is it easy to * if the diameters of the capillary vessels be merely dimi- nished, without being entirely obliterated, the small quantity of c 18 perceive in what manner it can proportionably lessen the afflux of blood to an inflamed part. If the ex- istence of spasm were proved, it would rather aggra- vate, than abate, congestion. John Brown made all diseases consist, simply, in an increase, or diminution, of natural action. Inflam- mation, according to his theory, arises from too great, or too littlej excitement in a part. But, surely, no alteration in the degree of the action of the vessels, could give rise to secretion, in which inflammation so often terminates. How can an agent, which only increases, without altering, the healthy action of the vessels, form a callus for the union of afracture, or pus from an ulcerated surface? If the justness of this doctrine be allowed, secretion becomes mere filtration; and, by a parity of reasoning, absorption is proved to be nothing more than the effect of cappillary attrac- tion. Brown's theory, or any extension or modi- fication of it that can be made, will not afford the least clue to the explanation of the phenomena of specific in- flammation. It, moreover, makes the same disease blood, which enters them will, indeed, pass on more rapidly; but still the amount transmitted must be less. To relieve this state of the vessels, we should increase the action of the heart by stimulants. Those of a diffusible nature are, in general, found best to accomplish this purpose, as they do not increase the vio- lence of the hot stage which follows. These are the means which are universally used to shorten the cold stage of febrile diseases, particularly of idiopathic fevers; arid on the other hand, the influence of sedatives and stimu- lants, in the order 1 have named them, is the most common re - mote cause of inflammatory diseases. 19 depend upon opposite states of a part. Active inflam- mation, he supposes, to be merely a rising of healthy excitement above, and passive inflammation, a sinking below, the salutary point of his pathological thermome- ter. But who ever saw a part pass the line of health, in sinking from the elevation of active, to the de- pression of passive inflammation; or the reverse of this? We often see fevers inflammatory in their . commence- ment, and typhus in their progress. In such cases, there is increase and diminution of action, in the same patient, at different periods of his malady. But Bruno- nian optics have never been keen enough to detect na- ture at the critical moment, when she passed the healthy state, in her progress from sthenic to asthenic in- flammation. John Hunter defined inflammation to be " an action of dilitation," " an increased relaxation of parts," "an action of the parts to produce an increase of size, to an- swer particular purposes," " an increased relaxation in the parts," " being, as he thought, left to elasticity alto- gether." &c. &c. The first and second of these explanations, if indeed it be not a misnomer so to call them, merely expresses the fact, that increase of the diameters of the smaller vessels does take place. This no one will deny. But, surely, it is not to be considered a cause of inflam- mation, although it may generally attend as a symptom. Shall we say, then with Hunter, that inflammation is an action of parts to produce an increase of size; or a re- newal of deficiencies, to answer particular purposes in the animal economy? Suppose we do; is any new idea 20 derived from such an explanation? I think not. To say that an action of parts takes place, because such an action is useful, or necessary, is, so far as regards rational explana- tion, to say nothing. In the elucidation of physical phenomena, we are to point out the means, which the Deity uses, to accomplish his purpose. But Mr. Hunter refers us immediately to the will of the Dei- ty; and we might as well say, as he in substance does, that inflammation is an action of parts, produced by the will of the Deity; for it is clear that all the purpo- ses of the Deity are useful. This mode of accounting for inflammation, would be exactly analogous to that of the philosophy of Greece and Rome, which referred the rise of water in tubes, when the pressure of the atmos- phere was diminished, or removed, to the abhorrence in which nature held a vacuum. Sensation, whether of pleasurable or painful nature, according to the hypothesis of Darwin, is the cause of " new motions, which constitute inflammation*." But it is indisputable that " new motions" of the affected or- gan, are not always generated in consequence of a sensa- tion of pleasure or of pain. So far from this is the fact, that the highest degrees of pleasurable sensations in apart, are never, in the ordinary course of nature, follow- ed by those new motions, which, according to Dr. Dar- win, are termed inflammation. Pain and pleasure, which last however we seldom experience in parts inflamed, are not perceived, until after the complete establish- ment of the disease. Sensations, therefore, whether pain- " New moiioi.. of the affected organ arc generated in consc- ience of the pain or pleasure, which constitutes inflammation. Zoonomi/v. 21 ful or pleasurable, are to be considered as symptoms, not as causes, of inflammation. Dr. Fowler published in 1737, his Quaedam de In- flammatione. The doctrines he maintained were not new, though his defence of them was probably the most able,1 that had at that time, been made. He adopted the opinion of Gorter, that inflammation depends upon an increased action of the capillary vessels. When the causes of obstruction which had been assigned by Boer- haave, were proved to have.no existence, it was taken for granted, too, that obstruction did not exist. Hence Dr. Fowler considered the fact to be well established, that the velocity of the blood through the inflamed parts is increased; and from this error a conclusion no less erroneous was drawn, that the action of the capillary vessels is increased by inflammation. Messrs. Allen and Lubbock, in the Medical Socie- ty of Edinburgh, about twenty five years since, advan- ced, and supported a theory, directly opposed to the no- tions then prevailing, upon the subject of the proximate cause of inflammation. They contended that inflam- mation is always attended by relative debility of the mus- cular powers of the capillary arteries. Dr. Wilson has since very ably defended the same opinion*. Neither of these gentlemen seem to have been aware that Prof. Vacca Berlingherii had, so early as the year 1765, laid down the same position. Another learn- ed writerf tells his readers, without meaning at all * Wilson on Febrile Diseases. Class, Phlcgmas. t Parr's Med. Diet. art. Inflammation. . 22 to derogate from the credit of Messrs. Allen and Lub- bock, that he had long held the same opinion. Dr. M'Lean* remarks that he communicated an opinion similar to that which I have mentioned, with regard to the proximate cause of inflammation to Dr. Duncan, in 1793, and until the time of his publication (1809) con- ceived his ideas on the subject to have been entirely original. Latta has very briefly advocated the same opi- nion, without any notice of its original author. Inflamma- tion, says he, "must appear to rather consist in a para- lysis, than a spasm of the vessels immediately affect- ed." Lerney on Local Inflammation and Opthalmia, notices the same opinion; but is altogether silent on the subject of its probable author.f Some of these writers must, no doubt, be considered as independant witnesses to the truth of the doctrine, that debility is an invariable attendant upon inflamma- tion—and so far as it goes, the fact is prima facie alto- gether in favour of the correctness of the theory. But in deciding the question of its original author, we may say with the poet: " Non nostrum inter vos tantas componere lites." However dates speak for themselves; and Vacca no doubt is entitled to the praise of having, amonga number of fanciful notions, derived from the age in which he * M'Lean on Hydrothorax. " In inflammation the action of the heart is frequently increased very considerably, while that of the inflamed vessels is always diminished." p. 257—8. Profi. 1. | System of practical Surgery by Latta, 1804,. p. 4. ct sequent. 23 lived, entertained opinions on the cause of inflammation, more correct and more reasonable than any of those of his predecessors*. Were we pointing out the achievements of the de- scendants of Esculapius in exploringthe pathology of in- flammation as did the spirit of Anchises, of the Cesarean ancestry to the hero of the Roman poet, well might we exclaim of Vacca, "Tu Marcellus eris." Nor would he less deserve this mead of praise, than he who was honoured with the verse. * Prop.. 1. Inflammatio cujusvis partis humani corporis nun- quam sit, nisi in ipsa parte sanguis coarcervetur et fere quies- cat. Prop. 2, Coacervatio et semistagnatio sanguinis, vel alius hu- moris corporis humani, in quamcumque ipsius corporis parte minime contingere potest, sine ipsius partis absoluta vel relitiva debilitate. Prop 3. Data eadem partis cujusdam debilitate, non solum coacervatio, et semistagnatio, sanguinis fiet in ipsius partis san- guineis vasculis, ut demonstratum est, verum etiam canales la- terales lymphaticas, et adiposos ipsius partis sanguis ingredi debet. Prop. 4. Ex majori collectione sanguinis in vasculis san- guineis alicujus partis, et ingressu ipsius in canales tarn lym- phaticas quam adipsos, et ex ejusdem sanguinis per ipsos, atque sanguineos canales lentissimo motu, inflammatio morbos in ea- dem parte oriri potest. Prop 5. Ex majori sanguinis in parte quacumque inflamma- tione, inflammatio pinguidenis composite, et in ea parte exist- entis, exorietur. Prop. 6. Ex enata inflammatione in aliqua humani corporis parte major sanguinis, et humorum quantitas in eadem partem influit, atque ideo tumor nccessario major fieri debet." Prof. Vacca, Berlingherii. £4 Seat of inflammation. Inflammation may take place in any part of the body in which there are vessels not, in their healthy state, carry- ing red blood. It arises most frequently in parts, which have the greatest number of such vessels, allowing readily of distention, and which are farthest from the centre of the circulation. The nails, hair, and cuticle, not being vascular, are never attacked by it. The bones, medul- lary substance, tendons, &c. are not so often the seats of it as the cellular tissue, the muscular fibre, and the glands.—Of secreting surfaces, which are, in general more liable to inflammatory affections than nonsecreting surfaces, the mucous are perhaps the most obnoxious to its influence. Anatomical account of the parts concerned in inflam- m-ation. The heart is an organ entirely muscular. The arte- ries proceeding from it are partly muscular and part- ly ligamentous. As we descend from the larger to the smaller branches, the ligamentous coat diminishes more, in proportion to the size of the artery, than the muscular one. Mr. Hunter has conjectured that this last exists alone, in the smaller arteries: the ligamentous coat being entirely wanting in them. The large veins have a pulsatory motion; whence it is inferred, that they possess muscular fibres. But the reverse of what exists in the arteries, is found to obtain in them; for the largest seem to possess the greatest, and, perhaps, the only share of muscular power. 25 The design of this arrangement is evident. The blood as it comes immediately from the heart, has a suffi- cient impetus to render unnecessary to its propulsion the exertion of much muscular power. But as it proceeds onward, through the arterial ramifications, it gradually loses it momentum, from the resistance it meets with by friction against the sides of the vessels. Muscu- lar power thus becomes more and more necessary to its motion; while, at the same time, the increased area of its channels, does not require it to advance with its former velocity, in order to the passage through them, of all the blood coming from the heart: according to a well known principle in hydraulics. As elasticity is that property of bodies, which dis- poses them to resume their shape, after it has been al- tered by the application of any power, with a force equal to that which produced such alteration; it is evident, that so far as the ligamentous coat of the arteries possesses this property, the momen- tum of the blood, which had been opposed, during their expansion by its elasticity, is returned by the contraction of the vessels, with the force of this power. If there be no fallacy m this view of the subject, it would appear that the elastic coat of the arteries is not directly concerned, either in retarding, or accelerating, the motion of the blood. Its action is entirely through the medium of the muscular coat; moderating that dis- tension, which a diminution of the muscular power of the capillaries, or an excessive action of the heart and larger vessels necessarily causes; and obviating that D 2d » tendency to obliteration in the minute arteries, which an increased exertion of their muscular power over the counteracting force of the blood, a tergo would otherwise occasion. The first of these states of the vessels, is denominat- ed inflammation. The latter is well exemplified in those appearances, which we observe in the cold stage of febrile diseases; and which, I presume, exist in the minute vessels, previously to the occurrence in them of inflammation; whether induced by the application of topical stimuli, or other causes. It is attended by dimu- nition of bulk and heat, and by paleness, obstruction of perspiration and secretion. For the want of any term in our language to express it, I shall call it the anaimatous* state of the vessels. Dr. Rush mentions, in his lectures, violent cases of opthalmya, in which no redness, or indeed any other symptom of inflammation, except great pain, was per- ceived. Coagulable lymph is not secreted to unite solu- tions of continuity in any part of the body, until a mo- derate degree of inflammation has supervened. There are acute febrile affections of the liver, so violent, or in which, as Dr. Rush says, the excitement is so far be- yond the point of inflammation, that no secretion of bile or appearance of inflammation is perceived. By bleeding, and the pursuance of the antiphlogistic regimen, inflam- mation is brought on. There are many such instances upon record, which it would be useless to enumerate. It will be allowed, that there is an affection of the san- guiferous system different from inflammation without in- * Derived from «»*