ARMED FORCES MEDICAL LIBRARY Washington, D. C. THE PROXIMATE CAUSE OF DISEASE: BY INDUCTION FROM THE LAWS OF ANIMATED NATURE. WITH AN Examination of the Theories QV TOWNSEND, REICH, DARWIN, RUSH, AND WILSON. By JOHN MACE, M. D.\ **>£-, - ___________________ _ _ ;, ' "" >»\ i, Artem Medicam denique videmus, fi a naturali Philofophia deftjftiatiitv n Empiricorum Praxi haud multum praftare—Medicina in Philofophia nop; J- f fundata, res infirma eft. Lord Bacont. PRINTED BT BUDD AND BARTRAU, FOR. THOMAS DOBSON, AT THE STONE HOUSE, N° 41, SOUTH SECOND STREET, l802. TO DOCTOR WILLIAM HAYES, OF MARYLAND. DEAR SIR, 1T has always been the cuflom, with authors to prefix a few lines of dedication to their writings when they laid them before the public. For this purpofe fome have addreffed them/elves to Deities both Pagan and Chriflian, It is however common among enlightened nations, to dedicate to fome illujlrious human charaSler whofe fame has fpread through thefcientifc worlds But I am bound to you by morefilken cords than could bind me tojuch a charaSler, and you might juflly reproach me were I not, on the prefent occafion, to pay you a tribute of gratitude and refpeSl. Permit me thus publicly 39S96>3 DEDICATION. publicly to declare, that under your direc- tion I commenced the Judy of medicine, and that I have often witnejjedyour Jkill and judgment in praSlice, but particularly injaving my own life. Your linwavering friendfnp, and your ardent deftre for my projperity and happinejs, have been much greater than I had any right to expeSl. Should my endeavours on the prejent fub~ jeSl, or on any other belonging to medical Jcience, meet with approbation andjuccejs, I Jhall ajcribe all to you. 'That health, happinejs and projperity may attend the remainder of your days, and that you may ever prove fuccefsful in all attempts to re- lieve the pangs of human nature, is the fervent wifh of ITour grateful Friend and Pupil, THE AUTHOR. TO DOCTOR ENNALLS MARTIN, AND DOCTOR STEPHEN THEODORE JOHNSON, OF MARYLAND, THE FOLLOWING PAGES ARE INSCRIBED, AS A TESTIMONY OF REGARD, BY THEIR SINCERE FRIEND, AND HUMBLE SERVANT, THE AUTHOR. * j*v PREFACE. THE proximate caufe of difeafe has gene-* rally been confidered as a fubject of the moft difficult inquiry. Without furveying the labours of more diftant times, to prove the truth of this remark, it will be fufficient to recolledfc the unfuccefsful attempts of Stahl, Boerhaave, Hoffman, Cullen, Darwin, and Rufh* So great have been the exertions of men of the moft fplendid talents in this refearch, that per- haps all further endeavours may be confidered as entirely fruitlefs. Such a confideration, however, cannot fatisfy an inquiring mind and one who will only view for a moment the prefent ftate of medical fcience. This ftudy which includes the deareft inter- efts of man, his health and exiftence, was in the primitive ages of the world confidered with other branches of knowledge, as an offspring of the fage parent philofophy. Hippocrates was the firft who broke the parental tie and caufed it to be a particular and independent profeffion ; but it is much to be feared that this great man by this adr. did more injury than all his labours were afterwards able to repair. For though viii PREFACE. though medicine might have kept pace with the illufive flights of many ancient philofo- phers, yet when the immortal Bacon, as a Co- lumbus in philofophy and a giant in the intel- lectual world, unfolded the true path to know- ledge, it would then have enjoyed a glorious opportunity of receiving the moft brilliant im- provements. The.feparation of medicine and philofophy at this important period, is much to be regretted, and perhaps this ufeful branch of fcience has fuffered an irreparable lofs. It is from this fepa- ration that fo many ghoftly and unconnected doctrines have fince prevailed among phyficians. Thefe illufive meteors have only ferved to glit- ter for a while and excite the attention of man- kind, but have then difappeared forever. If phyficians had followed the method of induction prefcribed by Lord Bacon, medicine would never have been difgraced with fuch rambling whims of the brain, and might have obtained all the advantages of its connection with philofophy. But however mortifying to the dignity of medical fcience, and however fhameful in the eyes of the true philofopher, no fyftematic writer from the time of Lord Bacon to Dr. Brown has followed this glorious me- thod : and it muft ever excite pain in the fcienti- fic mind to reflect, that while the cultivators of almoft PREFACE. ix almoft every art and fcience have been guid- ed by certain determinate rules, thofe whofe province it is to reftore the health of man fhould afilime a peculiar and independent rank, and allow themfelves to fport in the fairy fields of conjecture. Indeed fyftematic phyficians have not done even fo much as to let thofe for whom they were writing know what the rules of induction are, and whether it is neceffary to follow them in inveftigating fubjects of medical fcience. To this day, reafon and obfervation in conjunction are laid to be highly neceffary; but in what manner the reafoning is to be conducted has not been pointed out by any goodly phyfician. The mind is left to rove about in all the ma- zes of uncertainty and knows not where to find a refting place. To fuffer medical refearchers to follow their own propenfities is furely a deplorable circum- ftance, but it muft be ftill more regretted that a refpectable writer fhould make any remarks which have a tendency to excite with redoubled force fuch propenfities of the mind. Dr. Dar- win in the preface to his flrft volume of Zoono- mia obierves, a There are fome modern prac- titioners who declaim againft medical theory in general, not confidering that to think is to theorize, and that no one can direct a method B of X PREFACE. of cure to a perfon labouring under difeafe with- out thinking, that is without theorizing; and happy therefore is the patient whofe phyfician pofTeffes the beft theory." Ah! 'tis this thinking in fuch an irregular and confufed manner that has fo much obftruaed the progrefs of know- ledge, and caufed phyficians to build fo many bafelefs fabrics in medical fcience. Such fuper- ftructures as thefe have ever been liable to fall into ruins, and while theories and fyftems of medicine are formed in fuch a manner it is vain to expect they will ftand. This is the only reafon why the doctrines of many ancient and modern phyficians have funk into oblivion; and had the authors of them pofTeffed the forefight of a philofopher, they might have known that the fame of fuch doctrines would have been fhort. It difcover^- ed the utmoft vanity and at the fame time a bewildered imagination, to expect that they would command alafting reputation. It was perhaps the love of fame, which un- fortunately for mankind too often prevails over the love of, truth among phyficians, that pre- vented fyftematic writers fince the days of the great Bacon, from giving their readers a view of the new and only certain path to know- ledge fo happily pointed out by this immortal genius. While thofe writers erected their idols, if PREFAC^. xi if they had laid open the grounds of belief, the votaries of medical fcience would have been too apt to refufe homage to fuch creatures of human invention. The mind muft be puri- fied from falfe imaginations and perverted, notions before it is prepared to refka the light of truth, and a mind thus fmoothed and polifh- ed would not have been difpofecf to worfhip fuch falfe gods as have been conftruaed by Stahl, Cullen, Darwin and other fanciful au- thors. But I am happy in turning my eyes from fuch flimfy ftruaures built upon materials more fubtile than air, to view a more folid edi- fice upon a foundation firm as the exiftence of man himfelf. This is the fyftem of the late Dr. Brown, a man who for his ftupendous ta- lents and improvements in medical fcience, will long be remembered with admiration and regard. In forming his fyftem this author proceeded as every phyfician fhould have done, that is, he proceeded like a philofopher. He began not with wild conjectures, but with collea- ing faas and making indudions from. them. Viewing the ftate of man, Dr. Brown faw that he was an aclive being; he therefore con- cluded that he had a capacity of aaion. But as this aaion ceafed and death was produced, when xii PREFACE. when the fubftances furrounding man were withdrawn, he concluded that they aded upon him and fupported his exiftence. Life there- fore appeared to be a forced ftate. The aaion of the living fyftem Dr. Brown denominated excitement, and the capacity or difpofition to aaion he called excitability. This difpofition he perceivecf allowed of more aaion at one time than another by the fubftances furround- ing man; when thefe fubftances produced more aaion the excitability was faid to be ac- cumulated, but when they occafioned lefs aaion it was faid to be exhaujled; and when all aaion ceafed and death occurred, it difappeared alto- gether. The abfence of excitability or the ca- pacity of aaion by fubftances applied to the body, therefore, diftinguifhes the dead from the living ftate. When man was deprive'd of a part of the agents which furrounded him he became weak, and as this weaknefs was im- mediate upon the withdrawing of thofe agents, without the operation of any thing elfe, this debility was denominated direcl; but when all the agents had been applied for too long a time and the capacity of aaion had become lefs, debility was alfo occafioned ; but as this debi- lity was produced in a more circuitous manner by the ftimuli wearing away the excitability or capacity of aaion, it was called indirecl. As a PREFACE. xiii a capacity of adion and the fubftances which furround man were fufficient to account for the motions of the animal machine, Dr. Brown re- ceded as fuperfluous all fuch ghoftly beings as an Anima Medica or a Vis Medicatrix Natura, Such are the fundamental principles of the Brownonian fyftem; the reader will readily perceive that they exhibit a complete fpecimen of philofophic indudion from fads which oc- cur under daily obfervation. It is much to be wifhed that Dr. Brown had preferved the fame charader of a philofopher throughout his whole doctrines; but he has fometimes departed widely from it. To point out the errors and imperfedions of this author is a talk which cannot be performed at the pre- fent time. I fhall only obferve, that his doc- trine of difeafed excitement being nothing more than a different degree of healthy excitement, is totally overthrown by what occurs in mil- lions of inftances, as will be feen hereafter, and that his treatment of many difeafes from the aaion of exceflive ftimuli by the aaion of ex- ceflive ftimuli is contrary to his own principles as well as the eftablifhed maxims of philofo- phizing. This treatment inftead of driving out one devil by another is adding devil to devil. But reafon and experience both tend to fhow that in cafes of great debility after the exceffive aaion of ftimuli, as occurs in fome inftances of xiv PREFACE. of bilious pleurify and other forms of malig- nant fever, ftimulants are highly neceffary, and are the only remedies to be depended upon. Here the excitability appears to be accumulat- ed as in other cafes of indirea debility, which occafions the ftimuli to aa with fuch advan- tage. This accumulation of excitability with the weak aaion of the fyftem which attends it, appears to arife from a deficiency of the ufual quantity of oxygen received into the fy- ftem, as will appear more clearly hereafter, and hence the adminiftration of this fubftance promifes to be of the higheft utility. Blood- letting is generally hurtful in fuch cafes, as might be expeaed from the view of the fub- jed that has been given. But to return to the consideration of the doarines of Dr. Brown. It was not to be expeaed that this writer could form a fyftem fo complete as to with- ftand all further obfervation and inquiry. The rude and imperfea ftate in which he found medical fcience, together with his want of praaice, muft have greatly retarded the pro- grefs of his improvements. Had he poffefTed an opportunity of making extenfive obferva- tions, his enlightened and philofophic mind was well calculated to form the moft ufeful inductions. But when all the errors of Dr. Brown's doc- trines fhall have funk into oblivion, there will PREFACE. xv be enough left to ferve for the foundation of a future ftrudure which will be as lafting as me- dical fcience. Still it may be faid to this pro- found author, " Hail creative genius, by whofe fenfe divine " Sprung forth a glorious fyftem ever form'd to (nine. " Envy and prejudice in vain oppos'd thy migl^t *' And iEfculapius' felf acknowledg'd all thy right." A fyftem founded upon the fundamental principles of Dr. Brown, with the difcoveries in chemiftry and the other auxiliary branches in medicine, which fhall be finifhed off by ftrid indudive reafoning, .will not be liable, like the bafelefs fabrics that have gone before it, to moulder into obfcurity, though it may receive improvements from fucceeding obfer- vations and difcoveries. After Lord Bacon had pointed out the true road tp knowledge in medicine as well as every other branch of philofophy, and efpecially af- ter Dr. Brown, by availing himfelf of Lord Bacon's, refearches, had unfolded the true laws of the animal ceconomy and laid the founda- tion of a true fyftem of medicine, it might have been expeded that medical writers would have engaged in the proper method of invefti- gation: but however humiliating to the dig- nity of fcience, it muft be admitted that they have been too much difpofed to go the way of their fathers, and that many vifionary notions infeft xvi PREFACE. infeft the dodrines of the day. For the bene- fit of mankind and for the honour of phyfi- cians, it is to be hoped, that fuch notions will have but a fhort exiftence, and that no dodrine will be fuffered to appear in medical writings, but what is founded upon real phenomena and thofe indudions that can be fairly drawn from them. Taking the advantage of the laws of the animal ceconomy, together with thofe fads that occur under daily obfervation, I have at- tempted to unfold the proximate caufe of dif- eafe by fuch indudions as appear to be con- fiftent with found philofophy. The opinion contended for was formed at an early period of my medical ftudies by contemplating the dodrine of animal life. Whether it is juft is to be left to future decifion. Magna ejl Veritas et pravalebit. Should therefore the proximate caufe of difeafe which I have deli- vered, be founded in truth, it will do doubt, from the importance of the fubjed, be receiv- ed with candor and attention; but if proved erroneous, I hope it will not meet with even a momentary fupport, and for the advantage of medical fcience be fpeedily hurried away into an everlafting oblivion. J. MACE. April 12th, 1802. THE PROXIMATE CAUSE, &c. THERE have been various theories of the prox- imate caufe of fever delivered by phyficians, but only two authors have ventured to lay down a theory of the proximate caufe of difeafe in general. Thefe authors are the illuftrious Dr. Darwin and the celebrated Dr. Ruih. The principle which is contended for in the following differtation, will be applied to fever as well as every other form of mor- bid adlion, and it may therefore be expe&ed that fome notice fliould be taken of the different theories of the proximate caufe of fever that have been deli- vered by authors. This is .what I fhall proceed to do, and fhall afterwards hazard a few remarks upon the opinions of Dr. Darwin and Dr. Rufli. In profecuting this defign, it will be needlefs to go back into ancient times; neither will it be of any ufe to take notice of many of the modern theo- ries upon this fubjeft. The doclxines of Stahl and of Boerhaave now fleep with the authors, who had the boldnefs and ingenuity to bring them forward. The fpafmodic theory of Hoffman and Cullen, after C being ( 18 ) being refuted and baniflied from the fchools of medicine, has lately been revived by Dr. Currie of Liverpool, who attempts to fupport it by a train of hypothetical reafoning.* This author appears to have adopted this do&rine in preference to any other, merely becaufe of his fuccefs with the cold and warm bath in febrile affe&ions j and affords an example of the flight grounds upon which phyficians have often proceeded in admitting and conftru&ing theories. With all due deference to Dr. Currie as a learned and intelligent phyfician, his labours upon this fubjecl feem to exhibit a fpecimen of the efforts of an ingenious mind in pleading a bad caufe; and though his new modification of the fpafmodic doc- trine of fever fhoufd*glitter like a bubble for a mo- ment, it will foon be hurried away into that oblivion which awaits the final reception of all imaginary fpeculations. Indeed no hypothetical theory of the proximate caufe of fever can be expected to ftand. An opi- nion upon this fubjecT: muft be founded in fact, or a philofophic induction from real phenomena, and a fuperftru&ure of this kind will not be liable to moulder away into the elements of which it is com- pofed. But to come to fome original fentiments that have lately been advanced. The Reverend Mr. Townfend after rejecting the Cullenian do&rine fays, "For the proximate caufe of fever, therefore, I would affign the morbidly increafed irritability of the heart and arteries, and this * See Medical Reports on the Effe&s of Water, cold and warm, as a Remedy in Febrile Difeafes. (' *9 > this with either ftrong marks of vafcular excitement, or withfymptoms of nervous weaknefs and diflrefs; the former conflituting fynocha and the latter ty- phus."* It is difficult to underftand what this reverend and refpe&able writer intends to fignify by " morbidly increafed irritability •" but it would appear to be nothing more than morbid action, as he fays in the above quotation it is attended with ftrong marks of vafcular excitement, and afterwards, that it arifes from " the stimulus of acrid bile, indigefled food, vifcid ajid corrupted mucus, worms, virus, and other stimuli in the flomach and firil paffages." The examination of this theory will therefore come more properly in place hereafter, when a fimilar one though much more perfect will be confidered. The next theory to be taken notice of is that of Profeffor Gottfried Chriflian Reich of Erlangen, who places the proximate caufe of fever in a defi- ciency of oxygen in the fyflem. His words are, " The generic character or eifence of fever, the fymptoms of which I prefume are already known, confifts in an unnatural and general feparation and re-union of the mofl fimple particles of the human body, effected by the unnatural, abfolute or rela- tive, local, or univerfal diminution of oxygen." The author then goes on to explain how this di- minution of oxygen may take place, and the chief caufes he afligns are miafma and the impurity of the atmofphere in general, all eruptive poifons; and impreflions * Therapeutics, or a Guide to Health. London, 1801. ( 20 ) impreffions on the mind which dimmifh the exertion or activity of the mufcles, nerves, and veffels. After thefe confiderations he fays, " The proxi- mate caufe therefore of all fevers lies either in the prevention of the reception of oxygen, or in an un- natural application of it, or in an accumulation and evolution of carbone, hydrogen, fepton, fulphur, phofphorus, and of all other particles of the human body fuppofed to be fimple, and in the conjunc- tion of thefe matters, among themfelves, in binary, ternary, quaternary, and quintuple forms; and with fuch matters as have their accefs externally, which we comprehend under the names of caloric, light, magnetifm and electric matter."* In fupport of his opinion, the learned profeffor has related his fuccefs in all the varieties of fever by the adminiftration of oxygen in the form of acids. That a deficiency of oxygen does take place in fever appears from the moft correct reafoning upon the fubject. Dr. Cullen obferves, that in the cold flage of this complaint the refpiration is fmall, fre- quent, and anxious, and is fometimes attended with a cough. This function never returns to its ordi- nary ftate during the whole paroxyfm, and after this is over it is ftill cxercifed with more difficulty tharf in perfect health, as almoft every perfon muft have experienced. Here it fhould be recollected that refpiration is nothing more than a mechanical procefs, depending entirely upon the vigorous con- traction of the diaphragm and the intercoftal and abdominal * Medical Repofitory, vol. iv. ( ai ) abdominal mufcles, which are occafionally affifted by other powers. From the debility which pre- cedes the attack of fever thefe mufcles are deprived of a part of their energy, the thorax is thereby not dilated to its ordinary extent, and the inevitable confequence is that the ufual quantity of atmofphe- ric air is not received into the lungs. Hence a defi- ciency of oxygen occurs in the fyftem. This is what happens in common cafes; but fuppofe a per- fon to be debilitated by exceftive heat, cold, intem- perance, fear, or exercife, and expofed to the im- pure atmofphere of a foul fliip, jail, hofpital, or city, the confequence of fuch an expofure would be ftill worfe.* Let * I know of nothing that makes a pure atmofphere except a proper proportion of oxygen gas or pure air ; and when a chemift or a medical writer mentions an impure atmofphere, if he does not mean one in which there is a deficiency of pure air, I take it for granted that he is fpeaking of fomething like a mathematical point, for the phrafe fignifies nothing. There are but two ways in which the furrounding air can be conta- minated ; one is by fuch fubftances as form a chemical com- bination with the oxygenous portion, and the other by fub- ftances which are capable of exifting in a gafeous form with- out any combination, and therefore operate by fimple dilu- tion. In either of thefe ways the proportion of pure air will be lefs, which will conftitute an impure atmofphere, and it is prefumable that every one who knows what takes place in refpiration will admit, that in a given quantity of this atmof- phere inhaled into the lungs there will be lefs of the pure air received into the fyftem than there is in ordinary cafes from a pure atmofphere. It appears to be a deficiency in the oxy- genous portion of common air that forms what phyficians ( *.* ) Let it Hot be faid that thefe confiderations are vifionary and hypothetical j the palenefs and livid appearances of the fkin, the want of ordinary heat, the languid circulation and dark colour of the blood, which take place in many varieties of fever but par- ticularly in the typhus, fcorbutic, and fynochus or malignant ftates, all warrant the above conclufion. The reverfe of thefe occur from fupplies of oxygen Carried into the fyftem in health: and when it is faid have pleafed to call a pejlilential conjtitution, for difeafes of this character invariably occur in moift feafons and calm weather, both of which tend greatly, as every chemift knows, to occa- fion combinations of the pure air in putrefaction, as well as to dilute it, and prevent thofe vital ftreams which flow from abroad. All writers agree that an impure air is neceffary to the exiftence of malignant difeafes, and indeed it has been afTerted, that without fuch an air they can no more exift than combuftion without the prefence of pure air. If reafoning from analogy and the attributes of the Deity, be allowable, there appears to be nothing which would lead one to fuppofe that the Creator of man fhould permit a fubtile agent, fuch for inftance as electric matter, to iflue from earthquakes or volcanoes and deftroy millions of human creatures, without any pofllbility of being controuled by the power of man ; but if peftilential difeafes cannot occur as they fay without an im- pure air, men may prevent themfelves from inhaling this air by diffusing pure air obtained from manganefe throughout their habitations, which leads.to a pleating view of pneuma- tic medicine. Accurate experiments might be mentioned in direcT: proof of a deficiency in the oxygenous portion of the atmofphere, in places where typhus and malignant fevers have occurred, but this fubjeft muft be deferred until a future period. Vide Hales on the Ventilator, or Thornton's Philo- fophy of Medicine, vol. iv. p. 436. ( n ) faid that the above phenomena are produced 'from a deficiency of this fubftance, the opinion is not drawn from feigned hypothefes but from real facts, and is agreeable to the moft correct method of phi- lofophizing. This deficiency of oxygen in the fyftem, promifes hereafter the explanation of many circumftances at- tending acute as well as chronic difeafes, which can- not be accounted for in the prefent ftate of medical fcience. But to return to the fubject of fever. Although a deficiency of oxygen does occur, I do not intend to affert that it constitutes the proxi- mate caufe of this morbid affection, nor that it is produced in the manner mentioned by Profeffor Reich; for he appears to confider the human body as nothing but a chemical machine, the elementary parts of which are fubject to the laws of elective attraction, as in mixing fepton (azote) and oxygen to form feptic acid, or fulphuric acid and foda to form glauber's fait. This however is by no means warrantable in the prefent ftate of chemical phyfio- logy, and it is much to be feared that amidft all the pneumatic projects of the day, man will ftill be man, and chemical refearchers will never be able to de- compofe and recompofe him at pleafure, as they do the phofphoric and carbonic acids. The Creator of the world appears, for valuable purpofes, to have kept certain fecrets to himfelf which are not for mortals to pry into, and if it is allowable to judge what is of the moft hidden na- ture among vifible beings, the animating property of ( 24 ) of man would perhaps prefent itfelf to the mind. If man was capable of forming himfelf, he would at once be exalted to an equality of creative ikill with his Maker, and what would be the confequence every ferious and thinking perfon muft know. Smollet obferves in his Humphrey Clinker, that " There are myfteries in phyfic as well as in reli- gion, which we of the profane have no right to inveftigate. A man muft not prefume to ufe his reafon unlefs he has ftudied the categories, and can chop logic by mode and figure." This remark is well worthy of its ingenious author, and deferves the attention of every pneumatic phyfician.* The * It is hoped that no perfon will confider this as an attempt to depreciate the laudable endeavours of Beddoes, Thornton and Townfend. In a more enlightened age thefe benevolent chara&ers will certainly meet with juft applaufe ; and while they continue to cultivate the objetts of pneumatic medicine in conformity to the known laws of the animal ceconomy, they will ever be fuccefsful. It is from this fplendid region that medical fcience will receive its laft and moft brilliant im- provements. All I aim at is the project of confidering the phenomena of animated beings as nothing more than the confequences of a chemical compound. In the extenfive range of chemical fcience there does not appear a fingle ana- logy to lead to this conclufion. If the elementary parts of the human body were all mixed together they would form combinations according to the laws of ele&ive attraction ; fo that inftead of having one body there would be fcveral; but if thefe elementary particles are prevented from obeying the laws of affinity, as happens during the living ftate, every che- mical philofopher will readily grant that it is not by a chemi- cal agent, and therefore will forever elude all refearches upon the principles of this fcience. Vide Beddoes on Confumption and Scrophula, p. 189. London, 1801. ( *5 ) The chemical combinations of the elementary parts of the body mentioned by ProfefTor Reich, do not appear to be at all proved by any analyfis the ProfefTor has made in the time of fever, and as being mere flights of the imagination fhould be re- jected in all refearches after truth. The fuccefs of this learned and ingenious author by means of acid remedies, does not afford any fup- port to his opinion of the proximate caufe of fever. This complaint has often been cured by calomel and jalap, but no phyfician ever fuppofed that its prox- imate caufe confifted in a deficiency of thefe fub- ftances in the fyftem. I come now to confider the theories of Dr. Dar- win and Dr. Rufli. But before entering into the fubject it may be neceffary to obferve, that it is with great diffidence I venture to approach the doc- trines of thefe eminent authors. They have long been accuftomed to explore the regions of medical fcience, and their fplendid talents entitle their opi- nions to the utmoft candor and refpect. Even the very errors of fuch refpeftable ^gentlemen deferve attention, for at the fame time that they fliow the fallacy of human reafon they point out the neceffity of purfuing another road in fearch of truth. While therefore a youthful votary of fcience fhould venture to diffent from fuch authority, he will be influenced by proper fentiments of refpect; and fhould he ha- zard any remarks upon the doftrincs fupported by thefe refpeftable writers, he will not proceed upon frivolous grounds, but will endeavour to offer only j) fuch ( 26 ) fuch objections as appear to be infpired by the genuine fpirit of philofophy. The theory of Dr. Darwin will firft be confidered. According to this author, " All difeafes originate in the exuberance, deficiency, or retrograde action of the faculties of the fenforium as their proximate caufe; and confift in the difordered motions of the fibres of the body, as the proximate effect of the exertions of thofe difordered faculties. The fenfo- rium poffeffes four diftindt powers or faculties, which are occafionally exerted and produce all the motions of the fibrous parts of the body; thefe are, the fa- culties of producing fibrous motions in confequence of irritation which is excited by external bodies; in confequence of fenfation which is excited by pleafure or pain ; in confequence of volition which is excited by defire or averfion; and in confequence of affoci- ation which is excited by other fibrous motions. We are hence fupplied with four natural claffes of difeafes derived from their proximate caufes; which we fhall term thofe of irritation, thofe of fenfation, thofe of volition, and thofe of affociation."* The faculties of the fenforium Dr. Darwin fup- pofes are caufed by the prefence of a fubtile elaftic fluid, which he imagines to be fecreted by the brain, and is therefore denominated fenforial power or the fpirit of animation. " The fimilarity of the texture of the brain," fays he, " to that of the pancreas, and fome other glands of the body has induced the inquirers * Zoonomia; part fecond, Caldwell's edition. Preface page 17. ( *; ) inquirers into this fubject to believe that a fluid, perhaps much more fubtile than the electric aura, is feparated from the blood by that organ for the purpofes of motion and fenfation. When we recol- lect that the electric fluid itfelf is actually accumu- lated and given out voluntarily by the torpedo and the gymnotus electricus, that an electric fhock will frequently ftimulate into motion a paralytic limb, and laftly, that it needs no perceptible tubes to con- vey it, this opinion feems not without probability; and the Angular figure of the brain and nervous fy- ftem feems well adapted to diftribute it over every part of the body."* The phenomena of animal life are truly aftonifh- ing, far beyond any thing that exifts in the vifible creation. The actions of the human body have at all times been confidered as difficult of explanation. To relieve this difficulty, phyficians have called in the aid of a very attenuated fluid poffeffed of great mobility, and diftributed throughout the various parts of the nervous fyftem, which however only* ferves to make the fubjeft more difficult, and involve it in ftill greater obfcurity. This fubtile fluid was fuppofed by the ancients to be of an oily and fpirituous nature, and they there- fore denominated it " animal fpirits." Sir Ifaac Newton firft fuggefted the opinion that it refembled electric matter, and at the end of his Principia he has the following query. " Is not all fenfation per- formed and the limbs of animals moved in a volun- tary * Zoonomia, vol. i. p. 6. ( 28 ) tary manner, by the power of a certain fubtile fluid refemblmg electricity which we call aether."* Dr. Cullen appears to have taken up the hint thrown out by Sir Ifaac Newton, and called the fubftance " nervous fluid," and in his writings, but particu- larly the Materia Medica, he has carried the confi- deration of it in explaining various phenomena of the animal ceconomy, to the greateft extent of which his ingenuity was capable. Dr. Darwin next comes forward as an improver in this point of difficult re- fearch, and he has with more piaufibility given this wonderful being the name of " fenforial power," becauie it is fuppofed to be fecreted in the fenforium. Since Dr. Darwin has publifhed his Zoonomia, phy- ficians have been fo much perfuaded of the electric nature of this fubftance, that they have called it " the electroid fluid." The arguments in favour of this opinion, after all that has been faid, do not appear to be fatisfac- tory. The luminous flafties before the eye which have been fuppofed to give countenance to it, may, as Dr. Elliot obferves in his Medical Philofophy, be accounted * The notion of this great man, when confidered in con- nection with die dodrine of thofe who think the human body nothing more than a compofition of inanimate matter, forms a beautiful reprefentation in the mind. The aether or elettroid fluid appears to produce the motions of the planets round the fun, and it might be expected that people inftead of ftrolling about would move in continual ellipfes. This would exactly form Mr. Woodward's perfeB and living orrery, and anfwer all his purpofes in proving the fubftance of die fun, without any further trouble. ( 29 ) accounted for upon the principles of optics. The fluid which produces the phenomena of galvanifm, has been proved by the electrometer to be nothing more than electric matter, and confequently is no more concerned in mufcular motion and fenfation than the fparks which iffue from a prime conductor. The motion of a paralytic limb by an electric fliock can give no fupport to this opinion. It is impoffible to produce motion and give a capacity of it in ani- mal bodies by the fame fubftance at the fame time. Hence the electric fluid cannot at one moment both ftimulate and renew the fenforial power or fpirit of animation; and hence the fallacy of that theory which fuppofes oxygen, one of the moft durable and diffufible ftimuli in nature, to be the principle of irritability. It appears ftrange, that Dr. Dar- win fhould fuppofe that an electric fliock applied to a paralytic limb, could inftantaneoufly renovate a fluid which he contends is fecreted from the blood. The exiftence of an electric fluid in the torpedo and gymnotus electricus, is no proof of its being produc- ed by a fecretory action in the brain of thefe animals. This fluid pervades many bodies both animate and inanimate, and it is not improbable but the cecono- my and ftructure of the torpedo and gymnotus electricus may give rife to the accumulation and ne- ceffity of more of it than many other created beings. Philofophers fay, that when an effect is produced the caufe of that effect muft always be prefent, and indeed there is an abfolute neceflity that it fliould be fo, Electricity appears to be much concerned in the C 30 ) the production of aurorae boreaks, fire-balls, fhoot- ing ftars, ignes fatui, water-fpouts, whirlwinds and earthquakes. In thunder-ftorms it has been proved to be prefent. Yet there does not appear to be any animal in the atmofphere or the earth, who in parox- yfms of tremendous fury fhould be capable of fe- creting from his fenforium fuch enormous quantities of electric matter, to fpread terror and deftruction among the human race! Metals and many fimilar bodies poffefs the electric fluid, but no perfon ever imagined that they were provided with a brain for the production of this fubftance.* The opinion of a very * It is not intended by thefe remarks to affert that eleftric matter is ever generated or formed, and the expreffions here made ufe of are only conformable to the theory of its fecre- tion in the fenforium of animals. This fubftance exifted ori- ginally, and appears to be nothing more ttiah a modification of the fame fluid which in different circumfiances produces heat and light; for as an ingenious philofopher obferves, it has all the old properties of fire and fome of its new ones too. A very learned Rabbi affirms, that the Hebrew Shehe- kim fignifies both heat and light, or more properly the ethe- real or ele&roid fluid which caufes thefe phenomena, and which pervades the univerfe, producing the revolutions of the heavenly machine. He fays that as air in motion is wind, and in undulating vibrations found, fo the fhehekim or fubtile ether in motion is light, and in vibrations by fridHon, &c. is heat or fire. He believes that this fluid exifted in the original chaos out of which all material beings were formed. The opinions of this learned Hebraift and philofopher will ap- pear more evident, if it is recollected, that heat and light are abfolutely neceflary to the exiftence of all animated beings, and that none of thefe were created until every thing was ( 3* ) a very attenuated matter fimilar to electricity being fecreted in the brain, is therefore wholly unphilofo- phical, and leads to conclufions which no one would ever dream of admitting. But perhaps it may be faid, that the brain, as appears by its glandular ftructure, does fecrete a fluid for the purpofes of fenfe and motion, although this fluid may not refemble electricity. The exift- ence of a glandular ftructure by no means proves the occurrence of fuch a fecretion, or the liver, pancreas and kidneys, as well as other glands, would fend forth refrefhing ftreams of this animating fluid. Admitting the fecretion of a fluid in the brain which is diftributed through the nerves, it is pro- bable that this fluid is intended to prepare thefe or« gans for fenfation, as the fat which lubricates the mufcles, the fynovia which is fecreted in the joints, and the lymph in the cavities of the abdomen and thorax, are deftined to aflift the motions and func- tions, formed for their fupport. And if the fhehekim caufes the motions of the planetary orbs, there was an abfolute necefllty for its pre-exiftence, or thefe bodies would all have ruflied in- to confuficn as foon as they were created. The fame learned Rabbi fays, " the great conflagration fhall happen by a con- verfion of all the ethereal matter into devouring fire, a tra- dition of which went early into the world." What a grand reflection ! People in ancient times have been fuppofed to b: very ignorant, but this was not the cafe in the firft ages of mankind. He who received an account of the creation from the Author of it, and he who gave a fuitable appellation to the fubtile fluid which caufes heat and light, muft have pof- feflcd the moft fublime piinciples of philofophy. ( 32 ) tions of thofe parts.* But to fuppofe that the fluid fecreted in the brain is thefne qua non9 or primary caufe of motion and fenfation, is proceeding upon a very uncertain ground, and trefpaffing upon the boundaries of juft reafoning. If all motion in the animal body is owing to this fluid, as the advocates for its exiftence teach, no fecretory action of the brain could take place until this organ had previ- oufly prepared fome of the fluid it was intended to elaborate, which all will grant to be an impoffibility. Many animals exift without a brain, and ftill they have fenfation and motion. In the embryo before this organ is formed, and in vegetables where it has not been difcovered, motion is found to occur. If then fenfation and motion, the effects attributed to the fenforial power, both take place where there is no poffibility of its exiftence, to fay that thofe phe- nomena are caufed by this fubftance is contrary to the eftablifhed maxim of reafoning, which requires that the efficient caufe fhould always be prefent at the time an effect is produced. The idea of a nervous fluid or fpirit of animation, appears to be only a remnant of ancient notions in medicine, and it feems ftrange that the moft enlight- ened phyficians of the prefent day, while they have rejected all other errors derived from this fource, fhould ftill adhere to fuch an opinion. This fluid never has nor never will be difcovered, if it is of fuch a fubtile nature as the advocates for its * Hence the ftate of the brain in infanity. See Cullen's Practice. ( 33 ) its exiftence fuppofe. Every one accuftomed to tra- vel the alluring paths of true fcience, will readily agree to the firft rule of philofophizing laid down by the great Newton, which is, that no more nor any other caufes of natural effects ought to be ad- mitted, but fuch as are both known to exift and are fufficient for explaining their appearances. This is a golden rule; it is the true and proper teft to dif- tinguifh what is. founded in nature and truth, from what refts only upon the illufive dreams of the ima- gination. The doctrine of an animating fpirit or nervous fluid, muft therefore be difcarded as the offspring of an unbridled fancy. Indeed Dr. Darwin himfelf, after all his reafon- ings, appears to have been in great doubt concern- ing the exiftence of this fubtile agent; for, fays he, " this opinion feems not without probability," an expreffion which denotes the loweft degree of belief. Yet this very refpectable author confiders the prox- imate caufe of all difeafes to confift in the various ftates of this fluid, as appearing in morbid irritation, fenfation, volition, and affociation. From his dili- gent refearches this ingenious writer muft have been aware of the fate of hypothetical doctrines in all the different branches of philofophy, but particularly in medical fcience. The vague and innumerable con- jectures which were formed in ancient times concern- ing the ftructure and funftions of different parts of the human body, have all been difcovered by anu- tomifts to be deftitute of foundation. The Aura Vitalis of Van Hclmont; the Vires Confervatrices et ( 34 ) Medicatriccs Natura of Gaubius and Cullen; the Anima Medic a of Stahl and Nichols j the Mechanifm, Obstruction, Constriclion and heritor of Boefhaave; and the Spafm of Hoffman, have all vanifhed before the rays of fucceeding light. It is therefore furprifing that Dr. Darwin fhould have trufted the Zoonomia, and what he calls a natural claffification of difeafes, upon a foundation acknowledged by himfelf to be nothing more than probability, efpecially as thefe fubjects engaged fo much of his time and attention, and bid fo fair to ftand as lading monuments of his talents and compre- henfive views. An excellent philofopher obferves, that to believe firmly what has but a fmall degree of probability is a manifeft abufe of the underftanding. It would be treating Dr. Darwin too feverely to ap- ply this remark to him, although he appears, not- withftanding his acknowledgement, to have believ- ed firmly that his theory of difeafes was founded in nature; and perhaps it may more juftly be faid, that in forming this theory he was fired with too much of that brilliant imagination which adorned with fuch beautiful fcenery the lines of the Botanic Garden. Of all the difcoveries in fcience none have ever originated from conjecture. They have always been made in confequence of patient obfervation, by ac- curate experiments, or conclusions drawn by ftrict reafoning from obfervation and experiments; and thefe have at all times tended to refute, but not to confirm, the theories invented by men of genius and warm ( 35 ) warm imaginations. To fuppofe that the brain fe- cretes a fluid fimilar to electricity, is proceeding too much into the fairy fields of conjecture. If this fluid really had an exiftence, to conceive that it could pro- duce mufcular motion alone by the action of ftimuli, would be going very far indeed: but to fuppofe it capable of performing all the offices affigned by Dr. Darwin, furpaffes the utmoft comprehenfion. The whole doctrine concerning animal fpirits, a nervous or electroid fluid, a fenforial power or fpirit of ani- mation, fliould therefore be confidered as a fiction which ought to have no place in genuine philofophy. Indeed there appears to be no neceffity for calling into confideration a fubtile fluid in explaining the phenomena of animated nature. It muft be admit- ted that all bodies pofTefTed with life and motion are endowed with a peculiar organization. In addition to this they have an excitability or a capacity of vital action by the impreffion of external agents, which excitability, if not immediately produced by the or- ganization, is at leaft intimately connected with it. If thefe were perfectly underftood, all the pheno- mena of animated beings would then be brought to light; and until they are, clouds and darknefs will forever involve the fubject. Whether it is intended by the Benevolent Crea- tor of man that phyfiologifts fliould ever arrive at this ftate of knowledge, time alone can decide. But to call into confideration an unknown fubftance be- fore what is already known to exift is underftood, inftead ( 3« ) inftead of making a nearer approach, tends only to obftruct the road to truth. But perhaps it may be faid that there are difeafes produced by Sympathy or Affociation, which may occur without the prefence of an animating fpirit or fenforial power. This opinion however, it is pre- fumed, will, upon an accurate furvey of the fubject, appear to be deftitute of foundation. Dr. Darwin confiders the fympathetic or affociate motions of much importance in explaining many morbid phenomena in the human body. Upon thefe he has formed his theory of fever, which indeed may be regarded as the moft complete fpecimen of his doctrine upon the fubject. Of all the different parts of the fyftem under the influence of fympathy, Dr. Darwin feems to confider the ftomach as entitled to the greateft attention. The importance of this organ in the human body may with great plaufibility be inferred from a variety of circumftances. It exifts in moft if not all animals, while the brain, heart and lungs, are found to be deficient. It is of the utmoft neceffity to the con- ftitution of man, for befide being the receptacle of his aliment, whereby an agreeable and powerful fti- mulus is immediately diffufed over the whole fyftem, it prepares a fubftance which by being affimilated to his organization augments his bulk, gives him new vigour, and fupports the vital flame. But'by reafoning a priori from the anatomical ftructure of this organ and its dependence upon the arterial, nervous and mufcular fyftems, it would not appear ( 37 ) appear to poffefs primary and independent action, but to be entirely of a fecondary nature in influencing the movements of the animal machine. To this confider- ation may be added, that in the foetus in utero the brain and fpinal medulla firft appear after the heart, and the ftomach with the other abdominal vifcera are only evolved juft before the extremities. Thefe parts are probably formed according to their importance in the animal oeconomy, and from this view it might be concluded that the ftomach is of lefs importance in the actions of life than either the vafcular or nervous fyftems. But the human mind is incapable of rea- foning with any degree of certainty from firft caufes, and upon this fubject as well as every other which regards the nature and health of man, experience is the only fure ground on which to feek for truth. It will therefore be neceffary to have recourfe to the phenomena which take place in the fyftem in its healthy and morbid ftates, in order to fee whether the action of the ftomach is of a primary and inde- pendent nature, or whether it does not depend up- on the ftate of the arterial, nervous, and mufcular fyftems. It is a fact eftablifhed by the experience of many, that the healthy ftate of this organ becomes impair- ed by paffions of the mind, by exceffive cold or heat, and by the influence of too much exercife; but whether thefe act directly on the ftomach itfelf, or indirectly through the medium of the fyftems that have been mentioned, is the queftion now to be confidered. If t 38 > If a perfon under the fenfation of hunger, in con- fequence of the fudden information of fome agreea- ble news is feized with a paroxyfm of joy, the heart immediately begins to beat with increafed energy, the circulation of the blood becomes more rapid, in confequence of which an unufual glow of warmth is diffufed over the whole body, mufcular motion is more vigorous, the cheeks acquire a red colour, and pleafure is depicted in the countenance. After this tumult of the fyftem has in fome meafure fub- fided and the perfon begins to return to his ordina- ry feelings, his appetite then and not before is found to be greatly diminifhed, if not entirely gone. If on the contrary the fyftem is affailed by an unexpected paroxyfm of fear, grief or forrow, the ftrength all at once feems to flee away, the heart feels a fudden fenfation of weaknefs and appears as though fomething was wanting for its fupport, the circulation becomes flow and languid which occafi- ons a diminution of heat, while the countenance ac- quires a palenefs and by its downcaft look expreffes the mournful ftate of mind. After thefe phenome- na occur the ftomach is found to be affected, and the appetite is often wholly fufpended; but if the afflicting caufe is not of a durable nature, the fyftem returns to its ordinary ftate and this affection dif- appears. If, however, the depreffing paroxyfm is often renewed, a torpor of the whole arterial, ner- vous and mufcular fyftems occurs, and the ftomach thereby becomes more permanently impaired, confti- tuting ( 39 ) tuting the various fymptoms which occur in dyfpep- fia and hypochondriafis. Here the ftate of this organ is clearly feen to de- pend upon the condition of the other vital parts of the fyftem, as produced by the operation of a ftimu- lant or fedative paffion. The phenomena which attend the action of heat and cold as well as exercife, alfo prove the dependent nature of the ftomach in the moft fatisfactory manner. The modus operandi of thefe caufes is however well known to every one acquainted with medical fcience, and it is not neceffary here to enlarge upon the fub- jea. But to meet Dr. Darwin on his own ground, and come to the confideration of fever itfelf. Dr. Cullen who for his accurate defcription of difeafes will ob- tain immortal honour, fays, that upon the firft ap- proach of a paroxyfm of fever," the perfon is affect- ed, firft with a Iangour or fenfe of debility, a flug- gifhnefs in motion, and fome uneafinefs in exerting it, with frequent yawning and ftretching. At the fame time the face and extremities become pale ; the features fhrink, the bulk of every external part is di- minifhed, and the fkin over the whole body appears conftricted, as if cold had been applied to it. At the coming on of thefe fymptoms fome coldnefs of the ex- tremities, though little taken notice of by the patient; may be perceived by another perfon. At length the patient himfelf feels a fenfation of cold, firft in his back, but from thence puffing over the whole body.'3* Thh * Vidj Cullen's Practice with Rotherlnm's no'.cs, vol. :. page 28. American eduiorij iBcr ( 40 ) This chillinefs is what conftitutes the beginning of the cold ftage, upon the approach of which, fays the fame faithful obferver," the appetite for food ceafes, and does not return till the paroxyfm be over, or the fweat has flowed for fome time. Again he obferves, Cf as the cold ftage advances there frequently comes on a ficknefs and naufea, which often increafe to a vomiting of a matter that is for the moft part bili- ous." Here, in a morbid as well as a healthy ftate, the dependent nature of the ftomach upon the pri- mary moving powers of the fyftem is plainly to be difcerned. The fenfe of debility, the palenefs of the face, the flirinking of the features, the fenfation of cold, to which may be added the flownefs and weak- nefs of the pulfe, occurring upon the firft approach of langour, all fhow that the affections of the mufcular and arterial fyftems are entirely of a primary nature, while at the fame time the unimpaired ftate of the ftomach until all thofe phenomena have taken place, proves in the moft convincing manner, that the mor- bid conditions of this organ are of a fecondary or fymptomatic kind. Upon this ground alone Dr. Darwin's opinion of the fympathetic influence of the ftomach appears to be without foundation. But to come to a clofer ex- amination of the fubject. This ingenious author fuppofes that a torpid ftate of the above-mentioned vifcus is the caufe of continued fever with weak pulfe, by producing a debility of the heart and arteries in confequence of direct fympathy, while the action of the ( 41 ) the cutaneous capillaries is increafed by reverfe fym- pathy. This he imagines is more efpecially the cafe when this fever arifes from contagious or infec- tious matter received into the ftomach. But with all acknowledgements to Dr. Darwin's fuperior abilities, this opinion appears to be formed from a very inattentive view of the firft phenomena of fevers. During the rage of malignant epidemics, fuch for inftance as the yellow fever, it is a well known fact that the infectious caufe, if indeed it is received into the ftomach, exifts there without impairing its functions, and without producing any material injury in the fyftem, until by the operation of exceffive heat, cold, fatigue, fear, or intemperance, a ftate of debi- lity or predifpofition is brought on, by which the ex- citability becomes exceffive and enables the infection, before innocent, now to act, and occafion all the fymptoms of fever. The immortal Cullen, in his character of fevers, which he applies to all the exan-, themata as well as thofe of the intermitting, remit- ting and continued forms, fays, "Prasgreffis languore, laffitudine et aliis debilitatis fignis pyrexia fine morbo locali primario."* A torpor of the ftomach as the F firft * Synopfis Nofologlce Methodic*. CI. I. Ord. I. Febres. The reader will pleafe to excufe the fmall repetition here given of what was before quoted in Englifh from this author. Py- rexia fine morbo locali primario are words fo e-xpreffive and fo well fuited to die prefent purpofe that 1 could not forbear to mention them. A more detailed account of all the fymptoms of fever may be feen in the firft Chapter of Dr. Cullen's Prac- tice. ( 42 ) firft or primary affection of the fyftem in any idio- pathic fever whatever^ is therefore nothing more than an imaginary exiftence. To fay that this ftate of the ftomach may take place without its being per- ceived, is a manifeft abufe of the underftanding; be- caufe the fame reafon would juftify the conclufion, that it never can occur. Dr. Darwin's explanation of the above ftate of fever with weak pulfe, is by no means fatisfactory. He mentions the quicknefs of the pulfe and weaknefs of the heart and arteries, induced by breathing an at- mofphere with a diminiflied proportion of oxygen gas, as related by Dr. Beddoes, and after illuftrating the fubject a little in his own way, he exclaims, " How ex- actly this refembles a continued fever with weak and quick pulfe!" And "How exactly this fact overthrows Dr. Darwin's theory of this ftate of fever I" Be- caufe, if a weakened action of the heart and arteries is induced by breathing a reduced atmofphere or by a deficiency of oxygen, from the debility which pre- cedes and accompanies this fever, the cutaneous ca- pillaries having that " mobility" which Dr. Darwin mentions, will confequently be excited into action by the heat which furrounds the body. Hence all the phenomena of the fever will be produced without the affiftance of any previous torpor of the ftomach, or affociation ; and therefore to call thefe into confidera- tion is quite fuperfluous, and not confiftent with accu- rate reafoning. Dr. John Clark in his Obfervations on Fever, printed in London in 1792, has radically proved that ( 43 ) that this complaint is always the fame. Dr. Darwin admits this opinion. He alfo grants that the ftomach is affected fecondarily in fevers with ftrong pulfe j and if he had recollected the eternally eftablifhed rule, that effects of the fame kind are always produced by the fame caufes, he would never have thought of.a torpor of this organ as the primary caufe of any va- riety of fever whatever. Indeed the facts adduced in fupport of a fympathe- tic theory of difeafe are by no means fufficient, and almoft all of them may be explained in a fatisfactory manner upon principles which are more firmly efta- blifhed. Some affections however occur, which can- not be accounted for in the prefent imperfect know- ledge of the animal frame; fuch for inftance as a pain of the right fhoulder in an inflammation of the liver, and a fpafm of the legs in cholera, which are no more than fymptoms or effects of a morbid ftate of the fyftem; and no advantage is obtained by confider- ing them as produced by fympathy, a term which only ferves to exprefs the fact of their occurrence. Indeed fuch a conclufion appears to be very un- warrantable, becaufe it is by no means evident that the caufes of the original affection do not alfo pro- duce thofe which are of a fecondary or affociate nature. One of the moft remarkable inftances of fympa- thetic motion in the human body, occurs in the phe- nomena of refpiration. At the fame time that the diaphragm by its contraftion is drawn down, the m- tercoftal mufcles contraa, which elevate the ribs, C 44 ) and by thefe means the dimenfions of the thorax are increafed, when the true pabulum vita by trium- phant fprings flows into the lungs. Here the mo- tions are in direct oppofition, and to affert that one is the caufe of the other, would be almoft as contra- ry to reafon, as to fay, that when the flexor muf- cles of the hand contract, they excite the action of the extenfors. Inftead of actions in the human body exciting, they always tend to deftroy each other according to the one which predominates in the fyftem, except in thofe inftances where they ferve a common purpofe, as in the motions of the refpiratory mufcles. This principle, which was firft brought to light by the bold and original genius of Mr. John Hunter, is well eftablifhed and fupported by daily experience. But the facts which confirm this principle, tend en- tirely to fubvert the doctrine of affociate motions, and admit of no other,explanation, according to this doctrine, than that which is wholly of a fanciful na- ture.* Dr. Darwin has granted every thing necef- fary to overthrow his fympathetic theory. He ad- mits, that before* a part becomes difeafed, torpor or debility takes place, which is followed fooner or la- ter by an increafed difpofition to act by the impref- fion of ordinary ftimuli, except in thofe inftances where there occurs an irreparable exhauftion of the ' vital capacity. This debility is either of a direct or indirect * See Zoonomia, vol. iii. page 49, where fome facts of this kind are mentioned and explained according to Dr. Dar- win's method. ( 45 ) indirect nature, in whatever part of the fyftem it is produced, and will always be according to the cir- cumftances of the part affected, and the difpofition and force of the caufe by which it is induced. How difeafe is excited in thefe inftances, may be readily explained. Dr. Cullen long ago taught, that in confequence of the extended ftate of the vital principle, fubftances applied to one part of the fyf- tem excite motions in every other part j an opinion which will not be denied in the prefent ftate of medi- cal fcience. But without calling into confideration fuch a general operation, it is fufficient for the pur- pofe of producing difeafe, if thofe parts in a ftate of debility have their capacity of action increafed, a fact which is confirmed by daily obfervation. In confequence of this increafed capacity, when any fti- mulating agent is applied to the fyftem, it is obvious that its effects will be exerted principally upon thofe parts which are the moft fufceptible of its operation; and hence inordinate or difeafed action will occur without the affiftance of any fytnpathetic affection whatever. Dr. Darwin's theory of morbid affociations, when weighed in the balances of reafoning, is therefore found wanting. The fame golden rule of philofo- phizing which overthrows the doctrine of an animat- ing fpirit fecreted in the brain, applies with equal force to this theory ; for if the production of the above morbid affections can be accounted for upon known laws of the animal ceconomy, to call into con- fideration a fympathetic action, is totally inconfiftent with ( 46 ) with ffufc philofophy, and in fact appears originally to have exifted no where but in the imagination of its ingenious author. The theory of Dr. Rufli next comes in order to be confidered. But before making any obfervations upon the fubject, it will be proper to take a fhort view of the morbid ftate of the human body, as a preliminary to what will be delivered hereafter. If the Almighty fiat was only to withdraw for a moment the various agents furrounding man, all would then be calmuefs and repofe. But in the pre- fent ftate, a variety of ftimuli tend to fupport the vi- tal capacity, and prevent the flame of life from be- ing extinguifhed. The heart, by its never-failing contractions, conveys the vital ftream through all the body, which repairs the wafting frame, gives mufcular energy, and prepares the nerves for receiv- ing thofe affections which give rife to fenfation in the mind, while the intellectual and moral faculties, by their reverberating action, impart new Vigor to (he animated machine.. This is what conftitutes health, which like every other phenomenon in nature, has its degrees, and in which, though fome parts from poffeffing more of the vital capacity may be more active, yet an equal balance between the ftimuli and excitability is preferved throughout the whole frame. This nicely balanced machine is not eafily deran- ged, and hence man is capable of bearing without injury, a fmall proportion of what is either too much or too little. His action may be more, or lefs, and ftill < 47 ; ftill be healthy. But when the vital frame become? debilitated, the fcene is changed. By fome of the ordinary ftimuli ceafing to act, the excitability pre- vails to an exceffive degree. But how is the afpect then varied 1 The agents which are ftill permitted by the Almighty fiat to continue, inftead of produc- ing harmony in the whole machine, occafion nothing but deranged motions, which give rife to uneafy or painful fenfations in the mind : and now the whole frame rufhes with more than redoubled fpeed, to- wards destruction ! This is what conftitutes difeafe. But ftill the ma- chine is in motion, and as there is but one healthy, fo there can be but one difeafed action. This mor- bid, like the healthy ftate of the fyftem, has its de- o-rees. The action is fometimes ftrong and fome- times weak: the former is the fthenic and the lat- ter the afthenic affection of Dr. Brown. When dif- eafe belonged to the laft head, he called it a difeafe of debility, becaufe the excitement of the fyftem was weak ; for he exprefsly declares that as long as any of the ftimulating agents act, they have the. fame effect.* The difeafed, like the healthy action of the body, occurs more in fome parts than in others, or in other words, it is always more or lefs partial.! This de- pends as in health upon the degree of vital capacity poffeffed * Vide Brown's Elcments-by Dr. Beddoes, page 5. See alfo page 78, note. \ Brown's Elements, page 22 to 27. Alfo page S$ to 91. ( 48 ) poflfeffed by each part, and upon the nature of the agents which produce the morbid action. But al- though the grade of excitement confidered in itfelf, is more in one part than in another, yet in relation to the excitability prefent in each, and the ftimuli applied, it is of the fame degree throughout the whole fyftem, whether difeafe is either exceffive or deficient in action. It has been fuppofed that thefe oppolite ftates of difeafe, from a tranjlation of excitement or fome o- ther caufe, often prevail in different parts of the fyf- tem at the fame time; but this appears to be a great miftake, and would lead to the employment of two very contrary modes of practice; that is, to the ufe of depleting and ftimulating remedies at the fame time, for if the opinion was well founded, either of thefe would increafe the difeafe when applied alone. The tranjlation of excitement refts on nothing more than the prefence of an imaginary nervous, or eledtroid fluid, and there does not appear to be any other caufe capable of producing a difeafe of both weak and ftrong action at the fame time, while the living ftate of the parts is preferved. When the primary moving powers of the fyftem, fuch as the fanguiferous veffels, nerves, and mufcles, are affected, it is prefumed that all will admit, that the other parts are in a correfpondent ftate. This is remarkably illuftrated in cafes of fever, attended with great morbid action, when in confequence of the debility which precedes the attack, the excitabi- lity becomes exceffive in many different parts of the fyftem C 49 ) fyftem, giving rife to a variety of morbid affections, which are all fo eafily removed by depleting reme- dies that have a general operation. From this it appears that the want of mufcular energy in thefe cafes which is fo foon removed by blood-letting, is of the fame nature with the morbid action which prevails in the other parts, and feems to be unufually deficient by the predominating ex- citement of the heart and arteries. The fame correfpondence of excitement in differ- ent parts of the fyftem? occurs in difeafes of weak action, but efpecially in hypochondriafis, when a deficiency of excitement pervades the whole body. This deficient action is produced by an impaired ftate of the arterial, mufcular, and nervous fyftems, in confequence of fedative paffions, and is only to be removed by ftimulating remedies which have a general operation. Local affections alfo correfpond with the general ftate of excitement. This has been confirmed by the fuccefs which has attended the treatment of ul- cers of the legs, in confequence of remedies which operate on the whole fyftem, by Dr. Rufli and Dr. Phyfick. Thefe opinions are agreeable to experience and to the well known direction, that the ftate of the fyf- tem and the ftate of the pulfe are to regulate all prc- fcriptions. Dr. Brown has divided all difeafes into two kinds, which he calls fthenic and afthenic; but by the fame rule he might have faid that there was but one dif- G eafe, ( 5° ) cafe, for it is well known that a different degree or magnitude of an effect does not conftitute a difference in the nature of it, and befides he acknowledges that thefe ftates of the fyftem are apt to be converted into one another. Dr. Cullen in his Nofology obferves, that all dif- eafes may be confidered of the fame kind that arife from the fame caufes, that differ only in degree, and that are cured in the fame manner. In the time of this illuftrious author, phyficians were accuftomed to view the laws of the animal ma- chine in a very complex and irregular manner; they confequently conceived the difeafes of the human bo- dy to be of many genera and fpecics, and to be pro- duced by many caufes which were fuppofed to act in a very different manner. But happily for mankind a more perfect light has fince fhone upon medical fci- ence. By accurate reafoning from real phenomena, the true laws of the animal ceconomy, and the man- ner in which difeafes are produced, have at length been unfolded. Phyficians of the prefent day confi- der all the different varieties of morbid affection, as occafioned by caufes which act in the fame way. The caufes of difeafe are predifpofing, exciting, and proximate.* The * Medical writers have generally given place to a remote caufe of difeafe, but this does not appear to be neceffary or admiffible in the prefent ftate of medical fcience. The firft de- viation from health, confifts in debility, which is the predifpo- fing caufe ; and as all the ordinary ftimuli produce healthy action until this occurs, there appears to be no room for a re- mote caufe, unlefs die agents which occafion an equable ex- ( 5' ) The predifpofing caufe is always debility. This allows the excitability to accumulate to an exceffive degree. It occurs in one or more parts of the fyf- tem at the fame time, according to the circumftan- ces of the parts, and the nature of the caufe which produces the debility. Without debility and the con- fequent accumulation of excitability, difeafe could never be produced, except in fome inftances, from the application of preternatural ftimuli, which are as much of the nature of accidents, as a concuffion of the brain or a fracture of the cranium. The accu- mulation of excitability occurs in cafes of indirect as well as direct debility, or the torpor of the fyftem would continually increafe, until the flame of life was entirely extinguifhed. Befides, if. this accumu- lation did not take place after indirect debility, no exciting caufe could act to occafion difeafe, which experience proves to be the cafe. The exciting caufe of difeafe is always of one kind and that is a ftimulus. Cold nor any other fedative can never be an exciting caufe, for this is plainly denied by the term itfelf. Such agents only act by producing a greater aptitude in the fyftem, to be acted on by ftimuli which excite the difeafe, though this is fometimes performed fo quick as to lead to deception. Dr. Rotheram in his Practical and Explanatory Notes on Dr. Cullen's Practice of Phyfic, when fpeaking of the caufes of difeafe, very juftly obferves, that citement, can be confidered as tending to bring on difeafe, which is a downright contradiction. ( 5* ) that " the predifpofing is that which renders the body liable or capable of being affected by difeafe when the exciting caufe is applied. No difeafe can exift without an occafional or exciting caufe, yet it is neceffary that at the fame time, the ftate of the body fliould be fuch as to admit that caufe to take effect or act." Debility is therefore always the pre- difpofing caufe, and ftimulus always the exciting caufe of difeafe. The proximate caufe of difeafe will be confidered hereafter. It is fufficient for the prefent purpofe to obferve, that it is at all times the fame. Difeafe confifts always in morbid excitement. This appears from the confideration, that the ani- mal machine is always in action while life lafts; and as this action is at all times ordinate or inordinate, except during the fhort period of predifpofition, it follows that there is but one difeafed, as there is but one healthy action. This difeafed, like the healthy ftate of the fyftem, can therefore only vary in degree, and, like it, can never be reduced to claffes, orders, genera, and fpecies.* The * Medicine is likely to become a curious medley of ancient notions and modern doctrines, and phyficians are too fond of amufing themfelves with fingle fymptoms of difeafe. When all the functions of the body are exercifed in a natural man- ner, every one confiders this as the efFedt of a healthy adion of the fyftem ; and confequently the phenomena which appear after a difeafed aclion is produced, are the effefts or fymptoms of this difeafed adion. The caufes which occafion the mor- bid aclion will then be confidered as the caufes of the difeafe, ( 53 ) The cure of difeafe is always in the fame manner, and that is by removing the morbid excitement of the fyftem. When this excitement is exceffive it is reduced by abftracting ftimuli; the fyftem then re- turns to its healthy ftate by the operation of ordina* ry agents, except where the habit of body is weak, in which cafe it becomes neceffary to adminifter fome of the ftimulating medicines belonging to the Materia Medica. When the excitement is deficient, it is re- moved and the fyftem reftored to its ordinate action, by the latter remedies alone. All the various means of fubduing morbid excitement operate by tending to remove its proximate caufe ; for until this is done, the healthy ftate of the fyftem is never reftored. This will be confidered more particularly hereafter. Thus it appears, that according to the rules of Nofology there is but one difeafe. The claffification of the morbid affections of the human body muft therefore ceafe, becaufe there is no foundation for orders, genera and fpecies, but only for varieties. This is the way in which Dr. Cullen would have to proceed in confidering the fubject, if he were now alive and not thofe caufes which produce particular and diftinguifh- ing fymptoms, as in hosmoptyfis and obflru&ions of the liver. The latter method of proceeding was adopted at a time when the movements of the animal fyftem were but little under- ftood, and when fuch vague theories as morbid matter were the order of the day, and therefore it is wholly inconfiftent with found philofophy to follow it at the prefent time. It is a pity but what phyficians, like philofophers and logicians, would diftinguifh between caufes and effects in their inveftigations. ( 54 ) alive and to follow the rules laid down in his own Nofology.* Let it be remembered, that all cafes of afphyxia are here excluded from belonging to the morbid ftate of the fyftem. To include this affection in the catalogue of the morbid conditions of the human body, is contrary to the doctrine of animal life, and the * It is hoped that no perfon will confider the above remarks on nofology as any endeavour to lefTen the value of a fympto- /^ maboUgy of difeafe. It is the fafhion of the prefent day to difregard all nofology, which has a tendency to lead the mind from ftudying the hiftories of the various morbid affections of the human body. The laws of the animal ceconomy, it is true, are very fimple and eafily known in the prefent ftate of medical fcience; but the effects of the adtion in the living fy- ftem are much diverfified by the complicated ftrudture of the animal machine. In difeafe, experience fhows that all pre- fcriptions are to be regulated according to the ftate of the fyftem. This ftate can be known only by its fymptoms or effects, and however varied the protean monfter may be in its eourfe, the degree of morbid excitement muft be afcertained, or the phyfician muft prefcribe in a random manner. *Tb diftinguifh the morbid conditions of the human body is fome- times difficult, but in moft cafes it is poffible; for, as Dr. Cullen juftly obferves, if any one denies this, he might as well have faid that there is nothing in the medical art. It is unfortunate for mankind, that the votaries of medical fcience are ever difpofed to carry a favourite dodtrine to extremes, and in fupporting of it, to neglect the advantages which at- tend the oppofite fide of the queftion. But when the faftiion- able opinions of the day (hall be moderated into their proper ftandard, the labours of Sauvages and Cullen will be again reforted to as hiftories of the morbid ftate of the fyftem, and will ftand as monuments of their talents and diligent applica- tion, until difeafe fliall no more afflict the human race. ( 55 ) the propriety of it is exprefsly denied by the very fignification of a difeafed ftate. Afphyxia is a total fufpenfion of all the powers pf life j and if it had never been difcovered that perfons were capable of refufcitation in this ftate, they would always be con- fidered as radically dead and accordingly configned to interment. Hence this affection has been pro- perly called " fufpended animation" by Hunter, Fo- thergil and other writers. Many animals, it is well known, continue in this condition in cold countries for the greateft part of the year, and yet no perfon ever confidered them as under the influence of difeafe, for pain and mifery would then appear to be their moft natural ftate. Having premifed thefe obfervations on difeafe, the - theory of its proximate caufe as delivered by Dr. Rufh, comes now under confideration. The theory of fever taught by this refpectable author, has been applied by himfelf to difeafe in general, and there- fore to ftate this theory, will ferve as a fpecimen of the whole of his opinions upon the fubject. In order to render his theory of fever more fim- ple and intelligible, ProfefTor Rufh lays down a few general propofitions. " i. Fevers of all kinds are preceded by general debility. This debility is the predifpofing caufe. " 2. Debility is always fucceeded by increafed excitability, or a greater aptitude to be acted upon by ftimuli. " 3. The diminution or abftraction of one ftimu- Jus is always followed by the increafed action of others." The ( 56 ) The connection of excitability with debility, the ProfefTor fays, has lately been pointed out by the French phyficians in the terms " laxite vibratile," by Which they mean a liablenefs in the fyftem to be thrown into vibrations or motions by the predifpo- fition of debility. He then obferves, " That this vibratility, or difpofition to preternatural motion in animal matter, is the predifpofing caufe of fevers, is evident from their occurring in thofe ftages of life in which it is moft common, as in infancy, childhood, youth and middle life." " 4. The ftimuli which are the remote or excit- ing caufes of fever, act in a manner wholly different from what they do upon a body -in which there is no predifpofition to fever. c* 5. The ftimuli which induce the irregular action or convulfion of fever, act, for the moft part, pri- marily upon the fanguiferous, and particularly upon the arterial fyftem. " 6. There is but one remote caufe of fever, and that is ftimulus.* " 7. There is but one fever. " 8. All ordinary fever being feated in the blood- veffels, it follows of courfe that all thofe local affect tions we call pleurify, angina, phrenitis, internal dropfy * The remote caufe here appears plainly to be the exciting caufe. ProfefTor Rufh had before mentioned the caufes that produce debility, which are commonly called remote caufes. He is now treating of the fever after the debility or predifpo- fition has taken place, and the excitability has been accumu- lated. ( 57 ) dropfy of the brain, pulmonary confumption, and inflammation of the liver, ftomach, bowels, and limbs, are fymptoms only of an original and primary difeafe in the fanguiferous fyftem. ' " Having premifed thefe general propofitions I go on to remark," fays the profeffor, " that a fever (when not mifplaced) confifts in a morbid excitement and irregular action in the blood-veffels, more efpe- cially in the arteries." He afterwards fays, " This irregular action is in other words, a convulfion in the fanguiferous, but more obvioufly in the arterial fyftem." That this is the cafe he infers from the ftrict analogy between fymptoms of fever and con- vulfions. He mentions the particulars of this ana- logy, and finds it to hold good in no lefs than nine- teen inftances. After thefe propofitions and remarks, Profeffor Rufh then fays, " From the fa&s and analogies which have been mentioned, I have been led to believe, that irregular action or a convulfion in the blood-veffels, is the proximate caufe of fever." Such is the theory of the proximate caufe of fever and of difeafe in general, as taught by Dr. Rufh. Before proceeding to make any remarks upon this theory, I think it juft to paufe awhile and pay a tribute of refpect to its enlightened and benevolent author. As a phyfician, a profeffor, and a bene- faaor to mankind in general, the name of Dr. Rufh, it is hoped, will be tranfmitted with the higheft efteem to the moft diftant poiterity. Hundreds of the medical profeffion in the United States muft ever IX bear ( 58 ) bear in mind, with the fineft feelings of gratitude, what abundant ftores of the moft ufeful knowledge they have received from this excellent phyfician, in the moft agreeable manner, and fufficient to infpire the higheft intellectual and moral exertions. The improvements which he has made in medical fcience, and efpecially in the treatment of the difeafes of this climate, will long ftand as monuments of his talents for extenfive obfervation and diligent refearch. His love of truth, which often leads him to reject opi- nions that he thinks upon a more accurate furvey of the fubject were too haftily adopted, muft imprefs the fcientific mind with noble fentiments of refpect. It is the bufinefs of phyficians to reafon from facts and experience, and according to thefe he muft al- ter his opinions, if he would wifh to difcover truth which is fo defirable in whatever regards the health of man. To change an opinion under thefe circum> ftances, is the true charadteriftic of a philofophic mind. But while I exprefs all poffible acknowledg- ments to Dr. Rufh's fuperior talents and dignity, 1 muft beg leave to differ from him upon the proxi- mate caufe of difeafe, and I flatter myfelf with re- ceiving that mildnefs and indulgence, which flow from the fweetnefs of mind infpired by viewing the delightful walks of fcience. This is the more to be expected, as this juftly celebrated phyfician has clofed his theory with a diftinguifhed humility by faying, " It is imperfect from its brevity as well as other caufes. I commit it to my pupils to be corrected and improved." The V 59 J The objections to Dr. Rufh's theory are the fol- lowing. i. The proximate caufe is confounded with the difeafe itfelf. They both confift, it is faid, in mor- bid excitement or irregular action. This method of reafoning upon the fubject has long prevailed in me- dical fcience. It was adopted by Dr. Boerhaave, who was followed by Van Swieten, Gaubius, and many other phyficians. The proximate caufe or the difeafe according to them, was the refillt of all the other caufes united together. The caufes which in conjunction made up the proximate caufe, they de- nominated proegumenal or predifpofing, and proca- tarctick, occafional or exciting caufes. But in order to find out the propriety of Dr. Boerhaave's method of reafoning, it is only neceffary to recolleft the foundation upon which it was built. This illuftrious author confidered the human body to be compofed chiefly of a conic, elaftic, inflected canal, divided into fimilar leffer ones proceeding from the fame trunk. Thefe tubes are deftined for the conveyance of the animal fluids, in the circulation and undif- turbed motion of which he fuppofed life and health to confift, but when the fluids became obftructed in their paffage it conftimted difeafe. This obftruftion he fuppofed to confift for the moft part in a lentor of the blood, which he called the proximate caufe or the difeafe. Plethora or debility, as tending to favour the generation of this lentor, he called the predifpofing caufe, and heat or cold operating in ' conjunction with plethora or debility to produce the proximate ( 6"° ) proximate caufe or lentor, he denominated the occa- fional or exciting caufe. Thus it appears, that Dr. Boerhaave, from the chain of caufes he conceived to be concerned, was under the neceffity of confi- dering the difeafe and its proximate caufe the fame. He imagined the difeafe to confift in obftruction or lentor, and when this was removed a cure was com- pleted. There were but two other caufes concern- ed, which he called the predifpofing and exciting, and therefore to give the proximate caufe a place, it was neceffary to make it the fame as the difeafe. It is an eftablifhed maxim in philofophy, that rea- foning from one error always leads to another. Dr. Boerhaave's obftruction or lentor, it is well known, had no other exiftence but in his imagination, and therefore all reafoning built upon it muft be equally deftitutc of foundation. Truth in every branch of fcience is always confiftent with itfelf; and if Dr. Boerhaave's opinions had not been erroneous, there would have been no neceffity for him to contradict himfelf, by faying that the difeafe and its proxi- mate caufe, or the predifpofing and exciting caufes in conjunction, were the fame. In medical fcience as well as every other branch of philofophy, no one will pretend to deny, that all reafoning or inductions muft be founded upon facts and experience or real phenomena. Van Swieten himfelf very wifely re- marks, that " in the confideration of difeafes the difcoveries that obfervation has made are the data from which, when examined with attention and judgment, the ingenious phyfician infers numberlefs and ( 61 ) and moft ufeful truths:"* and if this author, as well as Dr. Boerhaave, his illuftrious preceptor, were now alive, they would accordingly throw off their old way of reafoning and adopt a method con- formable to the difcoveries that have lately been made in medical fcience. To follow the rules pre- fcribed by Dr. Boerhaave in inveftigating the caufes of difeafe, is not inferring truths from obfervation, but reafoning from the unfounded and exploded no- tions of lentor and obftruction. It is acknowledged that medicine has, within a few years, undergone a complete revolution. The phyfician who amidft the light of the prefent day, adopts the rules of reafon- ing dictated by an imaginary lentor, a£te therefore as inconfiftent with found philofophy, as a chemift would do to advocate the ancient doctrine of the elementary nature of the atmofphere, or the aftro- nomer who would adopt the vulgar notions of the Ptolemaic fyftem. Ihis is what every medical phi- lofopher muft grant, and it is ufelefs to infift any more upon the validity of the prefent objection. 2. There appears to be a great inconfiftency in Dr. Rufh's theory. He obferves that the proxi- mate caufe of difeafe confifts in morbid or irregular action, but in fpeaking of fyncope he fays, that its proximate caufe is an abfence of motion. 3. This theory does not appear to be agreeable to logical accuracy. The caufe and the effect are both faid to be one thing ; but he who mentions a caufe * Commentaries on Boerhaave's Aphorifms, vol. i. p. 29. ( 62 ) caufe of any kind, whether remote or immediate by his own expreffion, denies the poffibility of its being the fame with the effect it produces. A phyfician who reafons in this way, is like a chemift, who in explaining the manner in which carbonic acid or fix* ed air is formed, fliould fay it was formed of itfelf. Indeed it would be as good logic to fay, that every phenomenon in the univerfe was the immediate caufe of every phenomenon. 4. It is fuperfluous and ufelefs to fay, that difeafe and its proximate caufe confift in the fame thing. 5. According to this theory, fever has two pre- difpofing caufes, debility and " a difpofition to pre- ternatural motion in animal matter," or a connection between excitability and debility. Dr. Rufh ob- fcrves, that this connection of excitability with debi- lity, occurs in all other varieties of difeafe as well as fever, and therefore if fever has two predifpofing caufes, all other complaints have the fame. But he alfo fays that there is but one predifpofing caufe of difeafe, and that is debility alone. According to his own doctrine then, a difpofition to preternatural motion is not a predifpofing caufe, for he diftinguifh- es between this and debility. 6. The analogy between fever and convulfions, affords no fupport to this theory of the proximate caufe. According to the fecond rule of philofophi- zing, effects of the fame kind are produced by the fame caufes. Admitting the analogy between con- vulfions and fevers, and that they are different ef- fects, it cannot therefore be concluded that the con- vulfions ( «3 ) vulfions or one effect is the caufe of the other. The only deduction according to the eftablifhed rule juft: mentioned, is that the two effects are produced by fimilar caufes. 7. This theory of the proximate caufe does not ap- pear to be fufficiently adapted to the cure of difeafe. It has always been the practice among phyficians, not only to adminifter thofe remedies which fubdue mor- bid action, but likewife to give ftimulating medi- cines, in order to reftore the ftrength of the fyftem and remove the difpofition to a relapfe, which is apt to occur after all complaints, even from the ordinary proportion of ftimuli, while debility remains. From thefe confiderations it muft be clear to every medical philofopher, that Dr. Rufli's theory can by no means be admitted, and it therefore becomes ne- ceffary to inveftigate the fubject ftill further. This can only be done with certainty by ftrict reafoning, founded upon real phenomena of the living fyftem, and it is in this way alone that the proximate caufe of difeafe, as well as all other fubjedts belonging to medical fcience, can be brought to light. The word proximate is derived from the Latin. verb proximo, which fignifies to be next. A proximate caufe then is that caufe next to an effect, and there- fore the proximate caufe of difeafe is that caufe which is next to the difeafe. This caufe comes now under inveftigation. Except in fome few inftances of idiofyncrafy, and other fimilar affections, difeafe is always preceded by debility, or fuch an inability in the fyftem as ren- ders C 64 J ders a perfon unable to perform ordinary occupa- tions, without fymptoms of languor and wearinefs. Thofe idiofyncratic affections have generally been ex- cluded from the catalogue of difeafes, becaufe the term difeafe, almoft univerfally implies a more per- manent difturbance of the fyftem. There are alfo fome other affections produced by the application of violent ftimuli, which are entirely of the nature of accidents, and accordingly have been viewed in this way, as well as different from difeafes, by all medi- cal and furgical writers. But when thefe ftimuli occa- fion an action in the whole fyftem, indirect debility and a confequent accumulation of excitability occurs, and the complaints they produce are then in the fame ftate with thofe which at firft arife from this kind of debility. That indirect debility and an accu- mulation of excitability does occur, from the action of preternatural ftimuli, is proved by the intervals of pain and eafe which are always experienced in fuch cafes. But in general the morbid ftates of the fyftem are preceded by debility. This has before been proved to be the predifpofing caufe. When the debility is direct, the excitability is immediately accumulated, but when it is indirect, this does not take place un- til fome time has paffed away. But in both cafes the excitability is in a quite different ftate from what it is in an ordinary accumulation, fuch as occurs during fleep in a healthy ftate of the fyftem. Here the common ftimuli occafion ordinate or healthy action ; but after debility is brought on, there is fuch a.mor- bid ( 6S ) bid difpofition hi the fyftem, that they produce inor- dinate or difeafed action. This difpofition to difeafed action is what I have called a morbid excitability, and that fuch a ftate of excitability takes place, appears very evident for the following reafons: i. It occurs after debility. 2. It is in too great a proportion to the excite- ment. 3. When the ordinary ftimuli are applied, they produce a different effect from what they do in a found ftate of the fyftem, occafioning an inordinate or difeafed, inftead of a healthy action. Dr. Rufh himfelf obferves, that " the ftimuli which are the ex- citing caufe of fever, act in a manner wholly differ- ent from what they do upon a body in which there is no predifpofition to fever." As the ftimuli conti- nue to be of the fame nature, the difference in their mode of action muft be referred to a different ftate of the excitability or difpofition to produce action, as induced by the predifpofing caufe or debility. 4. When the difeafe is fubdued, there is a difpo- fition to morbid action even from the ordinary pro- portion of natural ftimuli, until the ftrength of the fyftem is reftored. Hence phyficians have at all times cautioned their patients againft returning too foon to their ufual habits of life, and hence the ma- ny relapfes and deaths which have occurred from not attending fufficiently to this caution. 5. This principle muft be admitted agreeably to the known laws of the animal ceconomy. Excite- I ment ( 66 ) ment is the living principle, or excitability brought into action by ftimuli. A certain ftate of excite- ment is then preceded by a correfpondent ftate of excitability. Therefore a morbid excitement can- not occur without a morbid excitability.* This mor- bid excitability or difpofition to difeafed action, as being next to the difeafe, is therefore the proximate caufe of the difeafe. Some have confidered the ftimulus that excites the difeafe as the proximate caufe j but an exciting caufe muft * The above conclufion is drawn from the dodrine of ex- citement and excitability, as taught by its illuftrious author. " In the firft promulgation of his dodrines, Dr. Brown did not fufficiently diftinguifh between the adions of the living body and its powers. Excitement and flrength were at firft confidered by him as fynonymous terms; and on the ftate of excitement his diftindion of difeafes was entirely founded. To the laft he had but two claffes ; difeafes of increafed and diminifhed excitement. After many difcuflions of his doctrine, in which the diftindion between the powers and actions of the living body was preffed upon by him, he' adopted the term excitability, to exprefs the difpofition in aaion." Beddoes's edi- tion of Brown's Elements, page no. " Contemplating the condition of man, Dr. Brown obferved that he was furround- ed by external agents, which aded upon him while alive, and their effects ceafed when dead. Thefe he called ftimuli; and the living principle brought into aclion by thefe, excitability; and the word excitement was ufed to exprefs the adion produ- ced by ftimuli." Philofophy of Medicine or Medic.il Extrads, vol. i. page 137. This is the only light in which excitement and excitability can be confidered, fo as to be confident with found real, ning and deftkure of imaginary notions. It was thought proper, in order to render the above argument plain, to iUte it in a fyllogiftic manner ; and he who admits Brown's dodrine, ::„uft alfo admit the dedudion dra.wn from it. ( 67 ) tnuft neceffarily be admitted, and befides, the ftimu- lus is more remote than the morbid difpofition, be- caufe it is applied to this difpofition, and acts on it in exciting the morbid action. But perhaps it may be faid, that difeafe may be prevented in cafes of debility by diminifhing the quantity of ordinary ftimuli, and therefore the exci- tability is not in a morbid ftate. This objection, fo far from being of any weight, is evidently in favour of the above principle ; becaufe there would be no neceffity for fuch a diminution if a morbid difpofition had not taken place in the fyftem. It might afford additional fupport to this doctrine, to inveftigate the predifpofing, exciting and proxi- mate caufes of health. The firft of thefe is however involved in the utmoft obfcurity ; and as I think it neceffary always to confine myfelf to a ftatement of facts, or real phenomena, and fuch deductions as can fairly be drawn from them, I fhall not offer any confiderations upon it. The exciting caufe of health is the fame as that of difeafe. The proximate caufe of healthy excitement, is a found or healthy ftate of the excitability. This conclufion is undeniable, from the fact, that excitement and excitability are always in a correfpondent condition. Since commencing the fubject of this differtation, and ftating the above arguments in favour of a mor- bid excitability or difpofition to difeafed action, I have met with a late Treatife on Febrile Difeafes, by Dr. Alexander Philips Wilfon. This ingenious au- thor has alfo taken notice of an alteration of the ex- citability, ( 68 ) citability, and has confidered this alteration as the proximate caufe of fever. His words are, " The laws of excitability are changed in fever. This change is fufficient to account for the phenomena ef- fential to fever, without fuppofing any change indu- ced on the fluids. " We know that thelaws of excitability, in fe- vers, are different from thofe which prevail in health; becaufe the fame external agents, the fame degree of exercife, the fame degree, of temperature, the fame quantity of food, of light, of found, &c. which in health occafion moderate excitement, followed by exhauftion, in fever produce exceffive excitement or atony. The ftate of the living folids being thus changed, there muft be a correfpondent change in the effects of the internal agents, the circulating and other fluids; hence the phenomena of fever. " The proximate caufe of fever, therefore, is a change in the laws of excitability; in confequence of which the fame agents no longer produce the fame effe&s. " How the remote caufes of fever act in inducing this change, and on what change in the living folid this change in the laws of excitability depends, we neither can nor ever fhall, perhaps, be able to de- termine. This part of the fubject is involved in the utmoft obfeurity. From the facts which have been dated, it is certain that the caufes of fever do effect this change; and it is evident that fuch a change in the living folid muft occafion the phenomena of fever."* But * Vol. i. page 529. See alfo vol. 2. Preface, page xvi. ( «9 ) But there is by no means a coincidence of opinion between Dr. Wilfon and me upon this fubject. He confiders the excitability as changed in the degree of its action, as appearing in atony or exceffive excite- ment ; whereas I fay it is changed in its very nature or difpofition, and is capable of producing the fame degrees of excitement according to the ftimuli which are applied, as in the healthy ftate of the fyftem. His expreffion is, that the laws of excitability are changed in fever. But this is certainly a miftake. The laws of excitability, or the laws of the animal ceconomy, are the following: i. When the excita- bility is not exceffive, a moderate degree of excite- ment is produced by a due proportion of ftimuli. 2. An accumulation of excitability enfues from a defi- ciency of direct ftimuli. 3. The exceffive action of ftimuli exhaufts the excitability. 4. When an exhaut tion is brought on, the excitability after a while be- comes accumulated.* In * Whoever confiders the afcendancy which the ftimuli have over the excitability in cafes of exhauftion, muft readily per- ceive, that if all the ftimuli were to continue their adion, the excitability could never accumulate, but the torpor of the fyftem would continue to increafe until life was extinguifhed. It has before been obferved, that in debility the refpiratory mufcles became weak, and the ufual quantity of oxygen was thereby not received into the lungs. This appears to be the only ftimulus which is deficient, after indirect debility or ex- hauftion takes place ; and as it is a very powerful ftimulus, a want of the ufual quantity may allow the excitability to accu- mulate. The fenfation of cold, the palenefs of the fkin, the weaknefs of the pulfe, and other phenomena of debility, feem clearly to fhow that diis deficiency of oxygen docs occur. ( 7° ) In order to be fatisfied that all thefe laws take place in difeafe, it is only neceffary to recollect the phenomena of an intermitting fever. The two laft laws of the excitability are exempli- fied in the firft paroxyfm and fubfequent return of this difeafe. At the latter end of the firft paroxyfm, the excitability is exhaufted, and before the com- mencement of the next it becomes fo accumulated*, and at the fame time fo morbid, as to occafion ex- ceffive and preternatural action again by the ordina- ry ftimuli. Between this exhauftion and accumula- tion; it is obvious that there muft be a time at which the ftimuli and excitability are in due proportion, and produce a moderate difeafed action. This ftate of the fyftem is however more ftationary in many other morbid affections, where there is a change from exceffive to weak action. In thefe cafes of moderate difeafed excitement, ftimulant medicines are apt to be hurtful, and phyficians are under the neceffity of tiling depleting remedies in order to produce a weak action, fo that thofe medicines may be exhibited. This is often the cafe in Rheumatifm which is about to alter from the acute to the chronic form, and is generally faid to partake of both thefe forms toge- ther. The accumulation of excitability from a defi- ciency of direct ftimuli, is fhewn by the effects of depleting remedies at the commencement of an inter- mitting, and after a cure has been completed: in the former cafe the paroxyfms are protracted, and in the latter a relapfe is apt to occur. Thefe effects arife from the accumulation of excitability ; while the depletion, by increafing the debility, renders / this fvt*, ( 7' ) this excitability ftill .more morbid, and hence the ordinary ftimuli more readily occafion preternatural acjion. Many other morbid ftates of the fyftem, befides thofe mentioned above, like wife fhow, that, the ex- citability is fubject to the fame accumulation and ex- hauftion in difeafe as in health. Dr. Wilfon is therefore miftaken, in fuppofing that the laws of excitability are changed in fever, or. indeed in any other difeafed affection : thefe laws evi- dently continue the fame, while the excitability is altered from a healthy to a morbid ftate. This change in the difpofition or ftate of the excitability, is the reafon why the ordinary ftimuli produce difeafed in- ftead of healthy action. The fact is, that Dr. Wilfon, although he has ventured to give fome ftridtures upon the Brunonian, fyftem, has ftill adhered too clofely to the principles of its original and profound author. He does not admit of any fuch thing as predifpofitioa to dheafe, which however is required upon the doctrines taughe by Brown himfelf; for if no ftate of the fyftem fa* vourable to the production of morbid excitement by the natural ftimuli ever occurred, thefe ftimuli would never occafion an excitement of this kind. But if fuch a ftate of the fyftem is brought on, it is evident that this ftate is predifpofition or the predifpofing caufe. Debility has before been proved to act in this manner.* Dr. * Every phyfician muft have noticed, that perfons often jky they are neither fick nor well, but weak. This is the ac- C 72 ) Dr. Wilfon has followed Dr. Brown, by confider- ing difeafe as confifting in nothing more than a dif- ferent degree of the fame excitement which confti- tutes health. Health, he fays, confifts either in mo- derate excitement, or fuch an exhauftion as daily occurs when the fleeping ftate of the fyftem is brought on by the various occupations of life j while excefc five excitement, or atony, which he obferves is pro- duced by exceffive excitement that lafts only a fhort time, conftitutes difeafe. According to this plan he forms his indications of cure. When the excitement is exceffive, it is to be removed by changing it into moderate excitement by depleting remedies, which diminifh the quantity of the natural ftimuli ; but when atony occurs, he fays it is to be removed by inducing moderate excitement by the application of ftimuli, efpecially thofe which are of a diffufible na- ture. It might excite furprife, to reflect that Dr. Brown, and thofe who have adopted his principles, fhould confider difeafe as a different degree of healthy ex- citement, did not two circumftances occur to the mind. The firft is, that fpeculative men in general. are as fond of their opinions as an epicure is of dainty difhes, and fuffer their minds to be deluded and led away by them in the fame manner. The fecond count that patients generally give of the ftate of their fyftem, previous to an attack of difeafe ; and this ftate is what con- ftitutes predifpofition. If the predifpofition is not removed, it feldom or never continues long without producing morbid ac- tion. ( 73 ) fecond is, that phyficians are always difpofed to fol- low one another, without putting their opinions to the teft of facts and philofophic inductions, or to ufe a phrafe from Dr. Cullen, they are for the moft part a fervile herd of imitators. It was before ob- ferved, that the human body was capable of bearing without injury a fmall proportion of what is either above or below the ufual ftandard. This is what every one muft have experienced; and if man had been fo flimfily made as to be liable to difeafe, from every, flight accident or deviation from his ordinary courfe of life, he might juftly complain againft the goodnefs and Wifdom of his Creator; for he would then be below the beafts that perifh. He could never maintain his rank and perform the duties and offices affigned to him upon the globe. But if it can be fhewn that every grade of excitement ever known to occur in difeafe, can take place in a healthy ftate of the fyftem, the unavoidable conclu- fion will then be, that difeafe does not at all regard the degree of excitement; and therefore the opinion of Brown and his followers upon this fubject, muft be deftitute of all foundation. For this purpofe it is only neceffary to furvey for a moment the different nations in the world, confut- ing of men, women and children. It is obvious, that in the different circumftances in which all thefe are placed, every degree of excitement known to take place in difeafe, muft occur in a natural or healthy ftate of the fyftem. But if thofe robuft inhabitants of the globe, which have lived at differ- K cnt C 74 ) ent times and been expofed to hard labour, are con- fidered from their embryo ftate, when they received the firft feeble motion of life, until the vital flame has been extinguifhed by old age, it will then ap- pear that every poffible degree of excitement has taken place. Yet in every one of thofe inftances, all the neceffary functions are carried on in a plea- fant, eafy and exact manner, which according to Dr. Brown himfelf conftitutes perfect health. The doctrine of difeafe confuting in a certain grade of excitement, either above or below the healthy ftandard, muft therefore, from the facts that have been mentioned, be acknowledged by all who are guided by juft principles in philofophy, to be wholly imaginary.* Neither does difeafe confift in the irregularity of excitement alone, as has been fuppofed. This may be eafily proved by confidering the manner in which the different labours and occupations of life are car- ried on in different parts of the world. In the pro- fecution of thefe it muft be obvious, that the greateft irregularity of excitement occurs; but no perfon will pretend to fay, that the different employments- amOngft * It is not a little curious, that thofe who have adopted this doctrine fhould be fo inconfiftent with themfelves as to plead for the exiftence of remote predifpofing and proximate caufes of difeafe ; whereas if difeafe was only a different de- gree of healthy excitement, as they fay, there could only be the fame caufes to produce it which occafion health. The immortal Brown, who was in general more confiftent with his own principles than any other phyfician, accordingly re- jected thofe caufes of difeafe. ( 75 ) amongft mankind are difeafes.* Befides, it has be- fore been proved, that the excitement in difeafe is in a correfpondent ftate throughout the fyftem, according to the excitability in each part ancl the ftimuli which act upon it. In order to prove this matter ftill further, it is only neceffary to obferve, that phyficians and furgeons directed by the never- failing guide of experience, always prefcribe accord- ing to the condition of the fyftem. When the ex- citement is exceffive they ufe depletion, and when it is weak they employ ftimulating remedies. But it muft be acknowledged that this would be a pre- pofterous as well as a pernicious method of proceed- ing, if the fyftem was not in a correfpondent ftate of excitement. Upon the whole it clearly appears, that difeafe depends upon fome other change in the living body befides an alteration in the laws of excitability, a different degree of healthy excitement, or an irre- gularity * The reader will pleafe to obferve, that if irregular excite- ment is mentioned as fynonymous with difeafe, it is not meant that this excitement conftitutes the nature of difeafe; for this dodrine is nothing more than the unguarded flight of fome adive imagination, not fupported by any facts and inductions whatever. It is intended here to maintain, that the excite- ment in difeafe is effentially morbid, and of as many differ- ent degrees as can poffibly occur in a healdiy ftate of the fy- ftem, from the period of infancy to that of death by old age. This is amply proved by only recolleding what appears in the different morbid affections of the body, from the gigantic exploits of die furious maniac, to the feeble and placid move- ments of the atrophic patient. ( 7°~ ) gularity of action. What this change is has been proved before. After having thus eftablifhed by undeniable facts, and inductions drawn from them, the principle of a morbid excitability or difpofition to difeafed action, I fhall now conclude by making a few remarks upon the application of this principle to medical fcience. i. It may perhaps be fuggefted to the mind, to inquire into the nature of this morbid excitability, in order to afcertain in what it corififts. This how- ever does not appear to be neceffary for the regula- tion of thofe remedies employed for the cure of difeafe, and it is fufficient for the purpofe to be ac- quainted with the fact. How debility occafions this difpofition to difeafed action, what is its particular nature, and how the natural and artificial ftimuli operate fo as to remove the debility on which it de- pends, are fubjects of the utmoft difficulty; and I am perfuaded that all the medical luminaries which are yet to ihine, will not be able to difpel the clouds of darknefs that hang around them. 2. This principle is happily adapted to the cure of difeafe, and is agreeable to the practice which has generally been followed, from the days of Hip- pocrates to the prefent time. When the difpofition to difeafe is' fo great as to occafion exceffive excite- ment, it fhould be counteracted by abftradting the natural ftimuli by bleeding and other depleting reme- dies. But at the fame time, if the depleting plan- is carried too far, it will bring on debility, which is the very caufe that firft occafioned the morbid dif- pofition. ( 77 ) pofition. A fear of this fliould, however, not lead to the employment of ftimulants too foon, which might bring on inflammation, congeftion, effufion, and all their dreadful effects. When this difpofition to difeafe exifts in a fmaller degree, giving rife to a moderate morbid excitement, it will be beft to ab- ftract fome of the natural ftimuli fo as to produce a weak excitement; for the application of ftimuli at firft would be apt to occafion exceffive action, and the confequent rifque of diforganization in thofe parts moft effential to life. In all cafes where the morbid excitement is weak, ftimulating remedies are to be employed alone ; and as the difpofition to dif- eafed action is never ftrong in thefe cafes, they may be given without danger to remove the debility, when this difpofition will ceafe altogether and a healthy one occur in its place. After morbid ex- citement has been fubdued in any manner, it muft be obvious that ftimulants are of great neceffity to remove the debility and difeafed difpofition which remain, and thereby prevent a relapfe. Succefs in the practice of medicine can only be obtained by a proper attention to thefe circumftances. 3. The knowledge of a morbid difpofition is of the utmoft importance in the prevention of difeafe. It proves in the moft fatisfactory manner, the abfo- lute neceffity of abftracting or avoiding fome of the natural ftimuli when debility has taken place. This may be beft accomplifhed by abftinence, and by reft in a horizontal pofture, until the fyftem is reftored to its ufual vigour, when the difpofition to difeafed ac- * tion ( 7s ) lion will entirely be removed. It is only by the diffu- iion of this knowledge, that the morbid affections in- cident to mankind can ever be prevented with any degree of certainty, where a weaknefs of the fyftem has been brought on. It may perhaps be faid, that feeble conftitutions require the addition of/timuli in order to avoid difeafed action. This however does not appear to be the cafe; becaufe the morbid dif- pofition is always excited by ftimuli, and there are no conftitutions when not oppreffed by too many of the means of excitement, but what have fuffi- cient powers of reftoration for warding off difeafe. But after the powers of the fyftem have been ex- •haufted by the continuance of difeafed action, fti- mulants are of, the greateft neceffity in fuch confti- tutions, and indeed are the only remedies to be de- pended upon. 4. The doctrine of a difpofition to difeafed action or ■a morbid excitability, leads to a pleafing view of the ultimate perfection Of medical fcience. This will be accomplifhed by teaching mankind in general the true laws of the animal ceconomy, and the nature of thofe caufes which weaken the fyftem and thereby give rife to this morbid difpofition. In the latter department of inftruction, chemiftry will hold the moft diftinguifhed rank. In order to prove the importance of this ftudy, in the perfection of the Healing Art, it is only neceffary to recollect, that almoft all, and certainly the moft deftrudtive difeafes of the human body, arife from varieties of heat and cold and from noxious effluvia in the at- mofphere. ( 79 ). mofphere. This noble fcience, by teaching the ef- fects of temperature, and by difcovering adequate means of guarding againft local impregnations from putrefaction, combuftion, exhalation and refpiration, will confer the greateft and moft lafting benefits upon the human race. The learned and elegant writers of the American Review, when fpeaking of the ad- vantages of chemiftry in medical fcience, very juftly obferve, that " this fair and fertile region conftitutes the medical land of promife, inviting attention by the fplendor of its fcenery, and alluring our hopes by the profufion of its riches. To us perhaps it will not be permitted to go over and poffefs the land; but we entertain no doubts of that bleffing being enjoyed by a more fagacious, inquifitive and fortunate pofte- rity."* Let it not be fuppofed that the above re- marks upon the perfection of medicine are the wild reveries of a heated brain. Reafon and experience both combine to fhow, in the moft ample manner, that as long as the animal machine is fubject to weaknefs, difeafe with all its numerous evils will be the confequence; for however mournful the reflec- tion, thofe means which before contributed to the health and exiftence of man now become the inftru- ments of his deftructiou ! * Monthly Magazine and American Review, vol. iii. pa-c 371. FINIS. Mad.. Mist WZ 8 6^ r c \ ■■■■■