^4m& -=€i. LECTURES UPON ANIMAL LIFE. THREE LECTURES UPON ANIMAL LIFE, DELIVERED IN THE UNIVERSITY of PENNSYLVANIA, v BENJAMIN RUSH, M. D. Professor of the Institutes of Medicike, and or Clinical Practice in the said University. Publijhed at the Request of his Pupils. PHILADELPHIA: PRINTED Br BVDD AND BARTRAM, FOR THOMAS DOBSON, AT THE STONE HOUSE. N° 41, SOUTH SECOND STREET. J 799. PREFACE. J\. REQUEST was made to me fome years ago by my pupils, to publifh the fol- lowing lectures. I declined complying with it, becaufe I did not think them fit for the public eye; but a more importunate applica- tion of the gentlemen who attended them last year, has prevailed upon me to commit them to the preSs in their prefent imperfea State. The reader will foon perceive, that I difclaim being the author of the great and original con- ception upon which they are founded. I have done but little more than carry the hod, to assist in completing part of a fabric, the foun- dations of which were laid by two of the most diftinguifhed master builders in medi- cine of the eighteenth century. I have VI THE PREFACE. I have endeavoured to render the facts and principles contained in thefe lectures, intelli- gible to gentlemen of all profeflions as well as to physicians. This attempt to diffufe medi- cal knowledge more generally, has been made necefTary, by the controverfies about fyftems of medicine, and remedies, which now di- vide the physicians of every part of the world. They can never be fettled, but by men who do not trade in phyfic, and who will not be actuated in deciding upon medical questions, by an improper competition for interest, or fame. BENJAMIN RUSH. Philadelphia, 7 itfhjune, 1799.J CONTENTS. LECTURE I. T Page. Introduction, - - . i The conftituents of perfett life in man, - - 5 Preliminary propofitions, 6 Of the ftimuli which produce life, - - - 8 Of external ftimuli, - - - - ' ibid. — Of light, ----- ibid. — found, - - , - . - 10 — odors, - - - - - 13 — air, - ibid. — heat, - - - - - - 14 — exercife, - - - - - * 15 — pleafures of the fenfes, - - - 16 Of internal ftimuli, - - - ibid. — Of food, ----- ibid. — chyle, - - - - - 18 — blood, - ibid. — tenfion of the glands, and of other parts of the body, - - - - - 19 — the exercifes of the faculties of the mind, ibid. Of the ftate of life in different parts of the day. - 24 LECTURE II. *iii CONTENTS. LECTURE II. Page. Of the ftate of animal life in fleep, - - - 26 ----------— in the foetus, - - - 34 -----------. in infants, - ibid. -----------in youth and middle life, - - 39 -----------in old age, - - - - 40 -----------in perfons who are blind, deaf, and dumb, 44 -----------in idiots, - - - - 46 -----------in perfons under the effefts of long fading, ibid. ——— in perfons fuppofed to be dead from drown- ing, freezing, and other caufes. - 50 LECTURE III. Of the ftate of life in the different inhabitants of the globe, as varied by civilization, diet, Situation, and climate, - - - - - - 55 Of the influence of certain mental ftimuli which aft nearly alike upon the individuals of all nations, 62 Of the caufes of life in all the different claffes of animals, 68 Of the caufes of life in vegetables, - - - 72 Of the caufes of death, - - - - 75 Inferences, from the doftrine of animal life being the effeft of impreffions upon the body. - ' - 78 LECTURES LECTURES O N ANIMAL LIFE. LECTURE I. Gentlemen,• JLvXY bufinefs in this chair is to teach the insti- tutes of medicine. They have been divided into Phyfiology, Pathology, and Therapeutics. The objects of the firSt are, the laws of the human bo- dy in its healthy ftate. The Second includes the hiftory of the caufes, and feats of difeafes. The Subjects of the third, are the remedies for thofe difeafes. In entering upon the first part of our courfe, I am met by a remark delivered by Dr. Hunter in his introductory lectures to his courfe of anatomy. " In our branch (fays the Doctor) thofe teachers who Study to captivate young minds with ingenious Speculations, will not leave a repu- B ration 2 LECTURES ON tation behind them that will outlive them, half a century. When they ceafe from their labours, their labours will be buried along with them. There never was a man more followed, and admir- ed in phyfiology, than Dr. Boerhaave. I remem- ber the veneration in which he was held. And now, in the Space of forty years,-------his phyfi- ology is------------------------it fhocks me to think, in what a light it appears."* Painful as this premonition may be to the teachers of phyfio- logy, it flibuld not deter them from fpeculating upon physiological Subjects. Simple anatomy is a raafs oS dead matter. It is phyfiolqgy which inSuSes life into it. A knowledge of the Structure of the hu- man body, occupies only the memory. Phyfiology introduces it to the higher, and more noble faculties of the mind. The component parts of the bo- dy, may be compared to the materials of a houfe, lying without order in a yard. It is phyfiology, like a fkilful architect, which connects them together, fo as to form from them an elegant, and ufeful build- ing. The writers against phyfiology, reSemble in one particular, the writers against luxury. They for- get that the Sunctions they know, and deScribe, be- long to the Science of phyfiology; jutt as the declaim- ed against luxury, Sorget that all the conveniences which * Left. :.i. p. 98. ANIMAL LIFE. J which they enjoy beyond what are poSTeSTed in the most Simple Stage of fociety, belong to the luxuries of life. The anatomist who defcribes the circula- tion of the blood, acts the part of a physiologist, as much as he does, who attempts to explain the functions of the brain. In this refpect Dr. Hunter did honor to our Science ; for Sew men ever explain- ed that Subject, and many others equally phyfiolo- gical, with more perSpicuity and eloquence, than . that illustrious anatomist. Upon all new and diffi- cult Subjects, there must be pioneers. It has been my lot to be called to this office of hazard, and drudgery ; and if in difcharging its duties, I fhould meet the fate of my predeceffors, in this branch of medicine, I fhall not perish in vain. My errors, like the bodies of thofe who fall in forcing a breach, will Serve to compoSe a bridge for thofe who fhall come after me, in our prefent difficult enterprife. This consideration, aided by just views of the na- ture, and extent of moral obligation, will overba- lance the evils anticipated by Dr. Hunter, from the lofs of posthumous fame. Had a prophetic voice whifpered in> the ear of Dr. Boerhaave in the evening of his life, that in the fliort period of forty years, the memory of his phyfiological works would perifh from the earth; I am Satisfied, from the knowledge we have of his elevated genius and piety. * LECTURES ON piety, he would have treated the prediction with the fame indifference, that he would have done, had he been told, that in the fame time, his name fhould be erafed from a pane of glafs, in a noiSy and vulgar country tavern. The Subjects oS the lectures 1 am about to deliver, you will find in a Syllabus which I have prepared, . and publifhed, Sor the purpoSe of giving you a Suc- cinct view of the extent, and connection of our courfe. Some of thefe Subjects will be new in lec- tures upon the institutes of medicine, particularly thofe which relate to morals, metaphyficks, and theology. However thorny thefe questions may ap- pear, we must approach and handle them ; for they are intimately connected with the history of the faculties, and operations of the human mind ; and thefe form an effential part of the animal ceconomy. Perhaps it is becaufe phyficians have hitherto been restrained from investigating, and deciding upon thefe Subjects, by an erroneous belief that they be- long exclusively to another proSeffion ; that phyfio- logy has So long been an obfcure, and conjectural Science. In beholding the human body, the first thing that Strikes us, is us life. This, of courfe fhould be ANIMAL LIFE. 5 be the first object of our inquiries. It is a most im- portant fubjea ; for the end of all the Studies of a phyfician is to prefervc life ; and this cannot be perfectly done, until we know in what it consists. I include in animal life as applied to the human body, motion —fenfation—and thought. Thefe three, when united, compofe perfect life. It may exist without thought, or fenfation ; but neither fenfa- tion, nor thought, can exist without motion. The lowefl grade of life, probably exists in the abSence of even motion, as I fhall mention hereafter. I have preferred the term motion to thofe of ofcil- lation, or vibration which have been employed by Dr. Hartley in explaining the laws of animal matter ; becaufe I conceived it to be more Simple, and better adapted to common apprehenfion. In treating upon this Subject, I fhall first confider animal life as it appears in the waking, andfleeping States in a healthy adult, and fhall afterwards in- quire into the modification of its caufes, in the fcetal, infant, youthful, and middle States of life, in certain difeafes, in different States of fociety, in different climates, and in different animals, I fhall begin, by delivering three general proposi- tions. I, Every 6 LECTURES^ ON I. Every part of the human body (the nails and hair excepted) is endowed with fenfibility, or exci- tability, or with both of them. By fenfibility is meant the power of having fenfation excited by the action of impreffions. Excitability denotes that property in the human body, by which motion is excited by means of impreffions. This property has been called by Several other names, Such as, irri- tability, contractility, mobility, and flimulability. I fhall make ufe of the term excitability, for the most part, in preference to either of them. I mean by it, a capacity of imperceptible, as well as obvious motion.—It is of no confequence to our prefent in- quiries, whether, this excitability be a quality of animal matter, or a fubftance. The latter opinion has been maintained by Dr. Girtanner, and has Some probability in its favor. II. The whole human body is fo formed, and connected, that impreffions made in the healthy State upon one part, excite motion, or SenSation, or both, in every other part of the body. From this view, it appears to be an unit, or a Simple and in- divifible quality, or Substance. Its capacity for re- ceiving motion, and SenSation, is varioufly modified by means of what are called, the fenfes. It is exter- nal ANIMAL LIFE. 7 nal, and internal. The impreffions which act upon it, fhall be enumerated in order. III. Life is the effect of certain stimuli acting upon the fenfibility, and excitability which are ex- tended in different degrees, over every external, and internal part of the body. Thefe stimuli are as neceffary to its existence, as air is to flame. Animal life is truly (to ufe the words of Dr. Brbwn) " a forced ftate." I have Said, the words of Dr. Brown; for the opinion was delivered by Dr. Cullen in the University oS Edinburgh in the year 1766, and was detailed by me in this School, many years before the name of Dr. Brown was known as a teacher of medicine. It is true, Dr. Cullen afterwards defert- ed it; but it is equally true, I never did ; and the belief of it, has been the foundation of many of the principles, and modes of practice in medicine which I have Since adopted. In a lecture which I deliver- ed in the year 1771, I find the following words, which are taken from a manufcript copy of lectures given by Dr. Cullen upon the institutes of medi- cine. " The human body is not an automaton, or felf-moving machine; but is kept alive, and in mo- tion by the constant action of ftimuli upon it." In thus aScribing the diScovery of the caufe of life which I fhall endeavour to eftablifh, to Dr. Cullen ; let it not be SuppoSed, 1 mean to detract from the genius ft lectures on genius, and merit of Dr. Brown. To his intrepidity in reviving, and propagating it, as well as for the many other truths contained in his fvftem of.medi- cine posterity, I have no doubt, will do him ample jultice, after the errors that are blended with them, have been corrected, by their unfuccefsSul applica- tion to the cure of difeafes. Agreeably to our last proposition, I proceed to remark, that the action oS the brain, the diaftole, and Syftolc of the heart, the pulfation of the arte- ries, the contraction of the mufcles, the peristaltic motion of the bowels, the abSorbing power oS the lymphatics, Secretion, excretion, hearing, Seeing, Smelling, tafte, and the SenSe of touch, nay more, thought itfelf, are all the effects of stimuli acting upon the organs of fenfe and motion. Thefe Stimuli have been divided into external, and internal. The external are light, Sound, odors, air, heat, exer- ciSe, and the pleaSures of the fenSes. The inter- nal Stimuli are Sood, drinks, chyle, the blood, a certain tenfion of the glands, which contain fecret- ed liquors, and the exercifes of the faculties of the mind ; each of which I fhall treat in the order, in which they have been mentioned I. Of external Stimuli. The first of thefe is light. It is remarkable that the progenitor of the human race ANIMAL LIFE. 9 race was not brought into existence until all the lumi- naries of heaven were created. The first impulSe of life, was probably imparted to his body by means of light. It acts chiefly through the medium of the or- gans of'vision. Its influence upon animal life is fee- ble, compared with fome other stimuli to be mention- ed hereafter ; but it has its proportion of force.— Sleep has been Said to be a tendency to death ; now the abSence of light we know invites to fleep, and the return of it excites the waking ftate. The late Mr. RittenhouSe informed me, that for many years he had constantly awoke with the firft dawn of the morning light, both in Summer and winter. Its influence upon the animal Spirits Strongly demon- ftrates its connection with animal life, and hence we find a cheerful and a depreffed State of mind in many people, and more efpecially in invalids, to be intimately connected with the prefence or abfence of the rays of the fun. The well known pedestrian traveller Mr. Stewart in one oS his vifits to this city informed me, that he had Spent a Summer in Lap- land in the latitude 0S690 during the greatest part of which time the fun was feldom out of fight. He enjoyed he Said during this period, uncommon health and Spirits, both of which he afcribed to the long duration, and invigorating influence of light. Thefe facts will furprife us leSs when we attend to the ef- C fects 10 LECTURES ON fects of light upon vegetables. Some of them lofe their colour by being deprived of it; marry of them difcover a partiality to it in the direction of their flowers ; and all of them difcharge their pure air only while they are expofed to it.* 2. Sound has an extenfive influence upon human life. Its numerous artificial and natural fources need not be mentioned. I fhall only take notice, that the currents of winds, the paffage of infects through the air, and even the growth of vegeta- bles, are all attended with an emiffion of found; and although they become imperceptible from ha- bit ; yet there is reafon to believe they all act upon the body, through the medium of the ears. The exiftence of thefe founds, is eftablifhed by the re- ports of perfons who have afcended two or three miles from the earth in a Balloon. They tell us that the filence which prevails in thofe regions of the * " Organization, fenfation, fpontaneous motion and life, exift only at the furface of the earth, and in places expofed to light. We might affirm the flame of Promethcus's torch was the expreffion of a philofophical truth that did not efcape the ancients. Without light, nature was lifelefs, inanimate and dead. A benevolent God by producing life has fpread or- ganization, fenfation and thought over the furface of the earth." Lavoiffier. ANIMAL LIFE. II the air is fo new and complete, as to produce an awful folemnity in their minds. It is not neceffary that theSe Sounds fhould excite SenSation, or percep- tion in order to their exerting a degree of stimulus upon the body. There are a hundred impreffi- ons daily made upon'it, which from habit, are not followed by fenfation. The Stimulus of ali- ment upon the Stomach, and of blood upon the heart and arteries, probably ceafe to be felt, only from the influence of habit. The exercife of walking, which was originally the refult of a deli- berate act of the will, is performed from habit without the least degree of confcioufnefs. It is un- fortunate for this, and many other parts of phyfio- logy, that we forget what paffed in our minds the first two or three years of our lives. Could we recollect the manner in which we acquired our first ideas, and the progreSs of our knowledge with the evolution of our fenfes, and faculties ; it would relieve us from many difficulties, and controversies upon this Subject. Perhaps this forgetfulnefs by children, of the origin and progress of their know- ledge, might be remedied by our attending more clofely to the first effects of impreffions, SenSation, and perception upon them as discovered by their little actions; all of which probably have a mean- ing, as determined as any of the actions of men or women. The 12 LECTURES ON The influence of founds of a certain kind in pro- ducing excitement, and thereby increasing life, can- not be denied. Fear produces debility which is a tendency to death.—Sound obviates this de- bility, and thus reftores the System to the natural, and healthy grade oSliSe. The School boy and the clown, invigorate their Seeble and trembling limbs, by whistling or finging as they pafs by a coun- try church yard, and the Soldier Seels his departing life recalled in the onSet of a battle by the noife of the fife, and of the poet's " fpirit Stirring drum." Intoxication is frequently attended with a higher degree of life than is natural. Now found we know will produce this with a very moderate portion of fermented liquor; hence we find men are more eafily and highly excited by it at public entertain- ments where there is mufic, loud talking, and hallooing, than in private companies where #there is no auxiliary Stimulus added to that of the wine. I wifh thefe effects of found upon animal life to be remembered ; for I fhall mention it hereafter as a remedy for the weak ftate of life in many difeafes, and fhall relate an instance in which a fcream Sud- denly extorted by grief, proved the means of re- SuScitating a perSon, who was SuppoSed to be dead, and who had exhibited the tiSual recent marks of the extinction >of life. 1 (hall ANIMAL LIFE. \$ I fhall conclude this head by remarking that perfons, who are deftitute of hearing and feeing, poffefs liSe in a more languid State than other peo- ple ; and hence ariSe the dulneSs, and want of Spi- rits which they diScover in their intercourse with the world. 3. Odors have a Sensible effect in promoting animal life. The greater healthinefs of the coun- try, than cities, is derived in part from the efflu- via of odoriferous plants which float in the atmof- phere in the Spring and Summer months, acting upon the System, through the medium of the fenfe of Smelling. The effects of odors, upon animal life, appear ftill more obvious in the sudden revival of it, which they produce in cafes of fainting. Here the fmell of a few drops of hartfhorn, or even of a burnt feather, has frequently in a few minutes restored the System, Srom a State of weakness bor- dering upon death, to an equable and regular de- gree of excitement. 4. Air acts as a powerful Stimulus upon the Sy- stem through the medium of the lungs. The com- ponent parts of this fluid, and its decomposition in the lungs, will be confidered in another place. I fhall only remark here, that the circulation of the blood 1^ LECTURES ON Wood has been afcribed by Dr. Goodwin exclusively to the action of air upon the lungs and heart. Does the external air act upon any other part of the body befides thofe which have been mentioned ? It is probable it does, and that we lofe our fenfati- on and confcioufnefs of it, by habit. It is certain children cry, for the most part, as Soon as they come into the world. May not this be the effect of the Sudden impreffion of air upon the tender furface of their bodies ? And may not the red color of their fkins, be occafioned by an irritation excited on them by the ftimulus of the air? It is certain it acts powerfully upon dinudated animal fibres; for who has not obferved a fore, and even the fkin when deprived of its cuticle, to be affected, when long expofed to the air, with pain, and inflammation ?— The stimulus of air, in promoting the natural ac- tions of the alimentary canal, cannot be doubted, A certain portion of it feems to be neceffarily pre- fent in the bowels in a healthy ftate. 5. Heat is an uniform and active ftimulus in pro- moting life. It is derived, in certain feafons and countries, in part from the fun; but its principal fource is from the lungs, in which it appears to be generated by the decompofition of pure air, anci from whence it is conveyed by means of the circu- lation, to every part of the body. The extenfive influence _________________________________________________ _______ _______^*%kfca ■___.___ ANIMAL LIFE. 15 influence o'f heat upon animal life, is evident from its decay and fufpenfton during the winter in cer- tain animals, and from its revival upon the ap- proach and action of the vernal fun. It is true, life is diminifhed much lefs in man, Srom the dis- tance and abfence of the fun, than in other ani- mals ; but this must be aScribed to his pofTeffing reaSon in So high a degree, as to enable him to Sup- ply the abstraction of heat, by the action of other Stimuli upon his System. 6. ExerciSe acts as a Stimulus upon the body in various ways. Its first impreffion is upon the muS- cles. TheSe act upon the blood veffels, and they upon the nerves' and brain. The neceffity of ex- erciSe to animal life is indicated, by its being kindly impofed upon man in paradife. The change which the human body underwent by the fall, rendered the fame Salutary stimulus neceffary to its life, in the more active form of labor. But we are not to fuppoSe, that motion is excited in the body by exer- ciSe or labor alone. It is constantly Stimulated by the pofitions of standing, fitting, and lying upon the fides; all of which act more or lefs upon muf- cular fibres, and by their means, upon every part of the fvftem. 7. The i6 LECTURES ON 7. The pleafures we derive from our fenfes have a powerful and extenfive influence upon human life. The number of thefe pleafures, and their proxi- mate caufe, will form an agreeable fubject for two or three future lectures. We proceed^ncxt to confider the internal stimuli which produce animal life. Thefe are I. Food. This acts in the following ways. 1. Upon the tongue. Such are the fenfibility and ex- citability of this organ, and fo intimate is its con- nection with every other part of the body; that the whole fyftem is invigorated by aliment, as foon as it comes in contact with it. 2. By mastication. This moves a number of mufcles and blood veffels Situated near the brain and heart, and of courfe imparts impreffions to them. 3. By deglutition, which acts upon Similar parts, and with the Same effect. 4. By its prefence in the stomach, in which it acts by its quantity and quality. Food, by dif- tending the ftomach, Stimulates the contiguous parts of the body. A moderate degree of distention of the ftomach and bowels is eflential to a healthy ex- citement of the fyftem. Vegetable aliment, and drinks, which contain lefs nourifhment than animal food, ferve this purpofe in the human body. Hay acts in the fame manner in a horfe. Sixteen pounds ANIMAL LIFE. If pounds, of this light food, are neceffarj; to keep up fuch;^, degree of distention in the Stomach and bowels of this animal, as to impart to him his natu- ral-grade of Strength and life. The quality of food, when of a ftimulating nature, Supplies the place of dsfteniion from it's cjuantity. A Single, onion will Support a lounging Highlander on the hills of Scotland for four and twenty hours. A moderate quantity of falted meat, or a few ounces of fugar, have fupplied the place of pounds of lefs Stimulat- ing food. Even indigestible Substances,, which re- main for days, or perhaps,weeks in .the stomach, exert a Stimulus there, which has an influence upon animal life. It is, in this way the tops of briars, and the twigs of trees, devoid not only of nourifh- ing matter, but of juices, fupport the camel in his journeys through the deferts of the Eastern coun- tries. Chips of cedar posts, moi(lened .with wa- ter, have Supported 'h'orfes for two or three weeks, during a long voyage from, Boston to Surinam; and the jncfigeftiule cover .of an old Bible, pre- ferved the life of a dog, accidentally confined in a room at New Castle upon Tyne, for twenty days. 5. Food Stimulates ,the whole body by means of the procefs of digestion which goes forward in the stomach. This animal Sunction is carried on in part by fermentation, in which there is an extrica- D tion 18 LECTURES ON tion of heat, and air. Now both thefe, it has been remarked, exert a Stimulus in promoting animal life. Drinks when they consist of fermented or distill- ed liquors, Stimulate from their quality; but when they consist of water, either in its simple ftate, or impregnated with any fapkl Substance, they act principally by distention. II. The chyle acts upon the lacteals, mefentcrfc glands, and thoracic duct, in its pafTage through them j and it is highly probable, its first mixture with the blood in the fubclavian vein, and its first action on the heart, are attended with considerable Stimulating effects. III. The blood is a very important internal sti- mulus. It has been difputed whether it acts by its quality, or only by distending the blood veffels. It appears to act in both ways. I believe with Dr. Whytt, that the blood Stimulates the heart and arteries by a Specific action. But if this be not ad- mitted, its Influence in distending the blood veffels in every part of the body, and thereby imparting extenfive and uniform impreffions to every animal fibre, cannot be denied.—In fupport of this afTer- tion it has been remarked, that in thofe perfons who ANIMAL LIFE. 19 who die of hunger, there is no diminution of the quantity of blood in the large blood veffels. IV. A certain tension of the glands, and of other parts of the body, contributes to fupport ani- mal life. This is evident in the vigor which is im- parted to the fyftem, by the fulnefs of the feminal veficles and gall bladder, and by the distention of the uterus in pregnancy. This distention is fo great, in fome instances, as to prevent Jfleep for ma- ny days and even weeks before delivery. It ferves the valuable purpofe of rendering the female fyftem lefs liable to death during its continuance, than at any other time. By increafing the quantity of life in the body, it often fufpends the fatal issue of pul- monary confumption, and ensures a temporary victory over the plague and other malignant fevers; for death, from thofe difeafes, feldom takes place until the ftimulus, from the distention of the uterus, is removed by parturition. V. The exercifes of the faculties of the mind have a wonderful influence in increafing the quan- tity of human life. They all act by refieilion on- ly, after having been previoufly excited into acti- on by impreffions made upon the body. This view, of the reaclion of the mind upon the body, accords with the Simplicity of other operations, in the 46 LECTURES ON the animal ceconomy.^ It is thus the brain re- pays the heart fbi* the blood it conveys to it, by reacting upon its mufcular fibres.—The influence of the different faculties of the mind is felt in the pulfe, in the ftomach, and in'the liver, and is Seen in the face, and other external' parts. of the. body. Thofe which act most unequivocally in pro- moting life, are the understanding, the imagination, and the pafFions-. Thinking belongs to the under- standing, and is attended with an obvious influ- ence upon the degree and duration of life. In- tenfe ftudy has often rendered the body infenfible to the debilitating *effefts of cold, and hunger. Men of great and active understandings, who blend with their Studies, temperance and exercife, are generally long lived. In fupport of this affertion, a hundred names might be added to thofe of Newton and Franklin. Its truth will be more ful- ly eftablifhed by attending to the ftate of human life in perfons of an oppofite intellectual character. The Cretins, a race of idiots in Valais in Swiffer- llnd, travellers tell us, are all fhort lived. Com- mon language justifies the opinion of the ftimulus of tire imderftanding upon the brain, hence it is common to Say of dull men, that they have Scarce- ly ideas enough to keep themfelves awake. M-. The ANIMAL LIFE. 21 The imagination acts, with great force upon the body, whether its numerous affociations produce pleafure or pain. But the paffions pour a constant ftream upon the wheels of life. They have been fubdivided into emotions and paffions properly fo called. The former have for their objects prefent, the latter, future good and evil. All the objects of the paffions are accompanied with defire or averfion. To the former belong chiefly, hope, love, ambition, and avarice; to the latter—fear, hatred, malice, envy, and the like. Joy, anger, and terror, belong to the clafs of emotions. The paffions and emotions have been further divided into Stimulating and Sedative. Our bufineSs at pre- sent is to consider their first effect only upon the body. In the original constitution of human nature, we were made to be Stimulated by Such paffions and emotions only as have moral good Sor their objects. Man was defigned to be always under the influence of hope, love, and joy. By the lofs of his inno- cence, he has Subjected himSelf to the dominion of paffions and emotions of a malignant nature ; but they poffefs, in common with fuch as are good, a ftimulus which renders them fubfervient to the purpoSe of promoting animal life. It is true, they are like the flimulus of a diflocated bone in their operation upon the body, compared with the action of antagonill mufcles Stretched over bones, which gently 22 LECTURES ON gently move in their natural fockets. The effects of the good paffions and emotions, in promoting health and longevity, have been taken notice of by many writers. They produce a flame, gentle and pleafant, like oil perfumed with frankincenfe in the lamp of life. There are instances likewife. of perfons who have derived strength, and long life from the influence of the evil paffions and emotions that have been mentioned. Dr. Darwin, relates the history of a man, who ufed to overcome the fatigue induced by travelling, by thinking of a perfon whom he hated. The debility induced by difeafc, is often removed by a hidden change in the temper. This is fo common, that even nurfes predict a recovery in perfons as foon as they be- come peevifh and ill-natured, after having been patient during the worst Stage of their ficknefs. This peevifhneSs acts as a gentle Stimulus upon the fyftem in its languid ftate, and thus turns the Scale in favour of life and health. The famous Benja- min Lay of this State, who lived to be eighty years of age, was of a very irafcible temper. Old Elwes was a prodigy of avarice, and every court in Eu- rope furnifhes instances of men who have attained to extreme old age, who have lived constantly un- der the dominion of ambition. In the courfe of a long inquiry, which I instituted Some years agp into the State of the body and mind in old people, I did not ANIMAL LIFE. 23 not find a Single perfon above eighty, who had not poffeffed an active understanding, or active paf- fions. Thofe different and oppofite faculties of the mind, when in excefs, happily fupply the place of each other. Where they unite their forces, they extinguilh the flame of life, before the oil which feeds it is confumed. In another place I fhall reSume the influence of the faculties of the mind upon human life, as they difcover themfelves in the different purfuits of men. I have only to add here, that I fee no occafion to admit, with the followers of Dr. Brown, that the mind is active in fleep, in prcferving the mo- tions of life. I hope to eftablifh hereafter the opinion of Mr. Locke, that the mind is always paf- five in found fleep. It is true it acts in dreams j but thefe depend upon a morbid State of the brain, and therefore do not belong to the prefent Stage of our Subject j for I am now confidering animal life only in the healthy State of the body. I fhall fay prefently, that dreams are intended to fupply the abfence of Some natural ftimulus, and hence we find they occur in thofe perSons most commonly, in whom there is a want of healthy action in th* fyftem 3ft LECTURES, Otf fflktm induced by the-excess, .or deficiency of cuS- tomary stimuli.. Life is in a languid State, in the morning. It acquires vigor by the gradual, and Sacceffive ap- plication of stimuli in the forenoon. It is in its most perfect ftate zrbout midday, and remains Stationary forfome hours. From the diminution of the fenfibility and contractility of the fyftem to the action of impreffions, it leffens ja the evening, and becomes again languid at bedtime. , Thefe facts will admit of an extensive application here- after in our lectures upon the practice of phyfic. LECTURE II. Gentlemen, The stimuli which have been enumerated,. when they act collectively, and within certain bounds, produce a healthy waking State. But they do not always act collectively, nor in the determined and regular manner that has been deScribed. There is in many States of the fyftem, a deficiency of fome Stimuli, and in Some of its states, an apparent abfence of them all. To account for the continu- ance ANIMAL LIFE* 25 ance of animal life under fuch circumstances, two things must be premifed, before we proceed to take notice of the diminution, or abfence of the ftimuli which fupport it. 1. The healthy actions of the body in the wak- ing state, consist in a proper degree of what has been called excitability, and excitement. The former is the medium on which ftimuli act in pro- ducing the" latter. In an exact proportion, and a due relation of both, diffufed uniformly through- out every part of the body, confifls good health. Difeafe is the revcrfe of this. It depends in part upon a difproportion between excitement and ex- citability, and in a partial distribution of each of them. In thus distinguishing the different ftates of excitement and excitability in health and SickneSs, you See I diffent from Dr. Brown, who fuppofes them to be uniform and equable, in the morbid, as well as the healthy states of the body. 2. It is a law of the fyftem, that the abfence of one natural Stimulus is generally Supplied by the increaSed action of others. This is more certainly the cafe, where a natural ftimulus is abstracted fuddenly; for the excitability is thereby fo inftantly formed and accumulated, as to furnifh a highly fen- fible and moveable furface for the remaining ftimu- E H 26 LECTURES ON H to act upon. Many proofs might be adduced in fupport of this propofition. The reduction of the excitement of the blood veflels, by means of cold, prepares the way for a full meal, or a warm bed, to excite in them the morbid actions which take place in a pleurify or a rheumatifm. A horfe in a cold stable eats more than in a warm one; and thus counteracts the debility which would other- wife be induced upon his fyftem, by the abstraction of the ftimulus of warm air. • Thefe two propositions being admitted, I pro- ceed next to inquire into the different degrees and ftates of animal life. The first departure from its ordinary and perfect State, which Strikes us, is in I. Sleep: This is either natural or artificial. Natural fleep is induced by a diminution of the ex- citement, and excitability of the fyftem by the con- tinued application of the stimuli which act upon the body in its waking State. When theSe ftimuli act in a determined degree, that is, when the Same number of Stimuli act with the Same Sorce, and for the Same time, upon the System; fleep will be brought on at the Same hour every night. But when they act with uncommon force, or for an unufual time, it is brought on at an earlier hour. Thus ANIMAL LIFE. 27 Thus a long walk, or ride by perfons 'accustom- ed to a fedentary life, unufual exercife of the understanding, the action of Strong paffions, or emotions, and the continual application of unufual founds feldom fail of inducing premature fleep'. It is recorded of Pope Ganganelli, that he flept more foundly, and longer than ufual, the night after he was raifed to the papal chair. The effects of unufual founds in bringing on pre- mature fleep, is further demonstrated by that con- stant inclination to retire to bed at an early hour, which country people diScover the firfl and fecond days they fpend in a city, expofed from morning till night to the noife of hammers, files and looms, or of drays, carts, waggons, and coaches rattling over pavements of Stone.—Sleep is further hast- ened by the abfence of light, the ceffation of founds, and labor, and the recumbent posture of the body on a foft bed. Artificial fleep may be induced at any time by certain stimulating Substances, particularly by opi- um. They act by carrying the System beyond the healthy grade of excitement, to a degree of indi- rect debility which Dr. Brown has happily called the lleeping point. The fame point may be induc- ed in the fyftem at any time by the artificial ab* ftraction 28 LECTURES ON (traction of the ufual ftimuli of life. For example. Let a perfon fhut himfelf up at mid-day in a dark room, remote from noife of all kinds, let him lie down on his back upon a foft bed in a temperate flate of the atmofphere, and let him ceafe to think upon interesting Subjects, or let him think only upon one Subject, and he will Soon fall afleep. Dr. Boerhaave relates an instance of a Dutch phy- fician who having perfuaded himfelf that waking was a violent ftate, and fleep the only natural one of the System; contrived by abstracting every kind of ftimulus in the manner that has been mentioned, to fleep away whole days and nights, until at length he impaired his understanding, and final- ly perifhed in a public hospital in a ftate of idiot- ifm. In thus anticipating a view of the caufe of fleep, I have Said nothing of the effects of difeafes of she brain in inducing it. Thefe belong to another part of our courfe. The fliort explanation I have given of its caufe, was neceffary in order to ren- der the history oS animal life, in that State of the System, more intelligible. At the usual hour of fleep there is an abstraction of the ftimuli of light, found and mufcular motion. The ANIMAL LIFE. 29 The Stimuli which remain, and act with an increas- ed force upon the body in fleep are, 1. The heat which is difcharged from the body, and confined by means of bed clothes. It is molt perceptible when exhaled from" a bed fellow. Heat obtained in this way, has fometimes been employed to reftore declining life to the bodies of old people. Witnefs the damfel who lay for this purpofe in the bofom of the king of Ifrael. The advantage of this external heat will appear further, when we confider how impracticable, or imperfect fleep is, when we lie under too light covering in cold weather. 2. The air which is applied to the lungs during fleep probably acts with more force than in the waking ftate. I am diSpoSed to believe that more air is phlogiflicated in Sleep than at any other time,* for the fmell of a clofc room in which a perfon has flept one night, we know, is much more disagree- able than that of a room under equal circumstances, in which half a dozen people have fat for the fame number of hours in the day time.—The action of decompofed air on the lungs and heart was Spoken of in a former lecture. An increaSe in its quantity mufl necelfarily have a powerful influence upon animal life during the fleeping ftate. 3. Refpira- 3° LECTURES ON 3. Rcfpiration is performed with a greater ex- tension, and contraction of the mufcles of the breaft in fleep than in the waking ftate; and this cannot fail of increafing the impetus of the blood in its paflage through the heart and blood veffels. The increafe of the fulnefs and force of the pulfe in fleep, is probably owing in part to the action of Fefpiration upon it. In another place I hope to elevate the rank of the blood veffels in the animal (economy, by fhewing that they are the fountains of power in the body. They derive this preemi- nence from the protection and fupport they afford to every part of the fyftem. They are the perpe- tual centinels of health and life; for they never partake in the repofe which is enjoyed by the muf- cles and nerves. During fleep, their fenfibility feems to be converted into contractility, by which means their mufcular fibres are more.easily moved by the blood, than *in the waking ftate. The di- minution of. fenfibility in fleep is proved by many facts to be mentioned hereafter; and the change of fenfibility into contractility will appear, when we come to consider the State of animal life in infancy and old age. 4. Aliment in the Stomach acts more powerfully in fleep, than in the waking ftate. This is evident from digestion going on more rapidly when we are awake ANIMAL LIFE* P awake than when we fleep.—The more flow the digestion, the greater is the Stimulus of the aliment in the ftomach. Of this we have many proofs in daily life. Labourers object to milk as a breakfast; becaufe it digests too Soon, and often call for food in a morning, which they can feel all day in their Stomachs. Sauffages, Sat pork, and onions are generally preferred by them for this purpofe. A moderate fupper is favourable to eafy and found fleep; and the want of it in perfons who are accustomed to that meal, is often followed by a reftleSs night. The abSence of its ftimulus is probably Supplied by a Sull gall bladder .("which al- ways attends an empty Stomach) in perSons who are not in the habit of eating Suppers. 5. The ftimulus of the urine, accumulated in the bladder during fleep, .has a perceptible influence upon animal life. It is often fo considerable as to interrupt fleep; and it is one of the caufes of our waking at a regular hour in the morning. It is moreover a frequent caufe of the activity of the understanding and paffions in dreams; and hence we dream more in our morning Slumbers when the bladder is Sull, than we do in the beginning, or middle of the night. 6. The 32 LECTURES ON 6. The feces exert a constant ftimulus upon the bowels in fleep. This is So considerable as to ren- der it leSs profound, when they have been accu- mulated for two or three days, or when they have been depofited in the extremity of the alimentary canal. 7. The partial and irregular exercifes of the understanding and paffions in dreams have an oc- cafional influence in promoting life. They occur only where there is a deficiency of other ftimuli. Such is the force with which the mind acts upon the body in dreams, that Dr. Brambilla, physician to the emperor of Germany, informs us, that he has feen instances of wounds in foldiers being in- flamed, and putting on a gangrenous appearance in confequence of the commotions excited in their bodies by irritating dreams. The stimulating paf- fions act through the medium of the will; and the exercifes of this faculty of the mind fometimes extend fo far as to produce actions in the mufcles of the limbs, and occafionally in the whole body, as we fee in perfons who walk in their fleep. The ftimulus of lust often awakens us with plea- sure or pain, according as we are difpoSed to re- Spect, or diSobey the precepts of our Maker. The angry and revengeful paffions oSten deliver us in like manner, from the imaginary guilt of murder. Even ANIMAL LIFE. 33 Even the debilitating paffions of grief, and fear, produce an indirect operation upon the fyftem that is favourable to life in fleep, for they excite, that diftrefling difeafe called the night mare, which prompts us to fpeak, or halloo, and by thus in- vigorating refpiration, restores the languid circula- tion of the blood in the heart and brain. Do not complain then, gentlemen, when you are bestrode by this midnight hag. She is kindly fent to pre- vent your hidden death. Perfons who go to bed in good health, and are found dead the fucceeding morning, are Said most commonly to die of this difeafe. I cannot difmifs the Subject of the Stimulating effects of dreams, without taking notice of an opi- nion of Dr. Darwin which is connected with it. He fuppofes dreams are never attended with vo- lition. The facts which have been mentioned, prove, that the will frequently acts with more force in them, than in the waking ftate. I proceed now to inquire into the State of animal life in its different stages. I pafs over for the pre- fent its history in generation. It will be fufficient only to remark in this place, that its firfl motion is produced by the flimulus of the male feed upon the female ovum: This opinion is not originally mine. F You ,4. LECTURES ON You will find it in Dr. Haller.* The pungent tafte which Mr. John Hunter discovered in the male Seed, renders it peculiarly fit for this purpofe. No fooner is the female ovum thus fet in motion, and the foetus formed, than its capacity of life is fup- ported, I. By the ftimulus of the heat which it derivet from its connection with its mother in the womb. 2. By the ftimulus of its own circulating blood. 3. By its conftant motion in the womb after the third month of pregnancy. The abfence of this motion for a few days, is always a fign of the indif- pofition or death of a fcetus. Confidering how ear- ly a child is accuftomed to it, it is strange that a cradle fhould 'ever have been denied to it after it comes into the world. II. In infants there is an abfence of many of the ftimuli which Support life.—Their excretions are in a great meafure deficient in acrimony, and their mental faculties are too weak to exert much influ- ence * " Novum foetum a feminis mafculi Jlimulo vitam con- cephTe." Elementa Fhynologiae, vol. viii. p. 177. ANIMAL LIFE. 35 ence upon their bodies. But the abfence of Stimu- lus from thofe caufes, is amply fupplied i. By the very great excitability of their fyf- tems to thofe of light, found, heat, and air. So powerfully do light and found act upon them, that the author of nature has kindly defended their eyes and ears from an excefs of their impreffions by imperfect vifion, and hearing, for feveral weeks after birth. The capacity of infants to be acted upon by moderate degrees of heat is evident from their fuffering lefs from cold than grown people. This is fo much the cafe, that we read in Mr. Umfreville's account of Hudfon's Bay, of a child that was found alive upon the back of its mother after fhe was frozen to death. I before hinted at the action of the air upon the bodies of new born infants in producing the red color of their fkins. It is highly probable, (from a fact former- ly mentioned) that the firfl impreffion oS the at- moSphere which produces this redness is accom- panied with pain, and this we know is a stimulus of a very active nature. By a kind law of fenfation, impreffions, that were originally painSul, become pleasurable by repetition, or duration. This is re- markably evident in the impreffion now under con- sideration, and hence we find infants at a certain age, difcover figns of an increafe of life by their delightful 36 LECTURES ON delightful gestures, when they are carried into the open air. Recollect further gentlemen, what was Said formerly, of excitability, predominating over fenfibility in infants. We fee it daily, not Only in their .patience of cold*, but in the Short time in which they ceaSe to complain of the injuries they meet With from falls, cuts, and even fevere Surgi- cal operations. i 2. Animal life is fupported in infants by their fucking, or feeding, nearly every hour in the day, and night when they are awake. I explained for- merly the manner in which food Stimulated the fyftem. The action of fucking, Supplies by the mufcles employed in it, the ftimulus of mastication. 3. Laughing and Crying, which are univerfal in infancy, have a considerable influence in promoting animal life, by their action upon respiration, and the circulation of the blood. Laughing exists under all circumstances, independently of education or imitation. The child of a negro Have born only to inherit the toils and miSery of its parents, re- ceives its mafler,with a Smile every time he enters his kitchen, or a negro-quarter. But laughing ex- ists in infancy under circumftances ftill more unfa- vourable to it, an inftance of which is related by Mr. Bruce. After a journey of feveral hundred miles ANIMAL LIFE. 37 miles acrofs the Sands of Nubia, he came to a Spring of water fhaded by a Sew Scrubby trees. Here he intended to have rested during the night, but he had not Slept long, before he was awakened by a noife which he perceived was made by a folitary Arab equally fatigued, and half famifhed with himfelf, who was preparing to murder and plun- der him. Mr. Bruce rushed upon him, and made him his prifoner. The next morning he was joined by a half Starved female companion, with an infant of fix months old in her arms. In paffing by this child, Mr. Bruce fays it laughed and crowed in his face, and attempted to leap upon him. From this fact it would Seem as if laughing was not only characteristic oS our Species, but that it was early and intimately connected with human liSe. The child of thefe Arabs had probably ne- ver feen a Smile upon the faces of its ferocious parents, and perhaps had never, (before the fight of Mr. Bruce), beheld any other human crea- ture. Crying has a considerable influence upon health and life in children. I have Seen So many instances of its falutary effects, that I have fatisfied myfelf that it is as poffible for a child to " cry and be fat," as it is to " laugh and be fat." 4- Ag 38 LECTURES ON 4. As children advance in life, the constancy of their appetites for food, and their difpofition to laugh, and cry, leflcn, but the diminution of thefe Stimuli is Supplied by exerciSe. The limbs, and tongues of children are always in motion. They continue likewife to eat oftener than adults. A crult of bread is commonly the last thing they afk for at night, and the firfl thing they call for in the morning. It is now they begin to feel the energy of their mental faculties. This stimulus is aflifted in its force, by the difpofition to prattle which is fo universal among children. This habit of converting their ideas into words as fast as they rife, follows them to their beds, where we often hear them talk themselves to fleep in a whifper, or to uSe lefs correct, but more Striking terms, by thinking aloud. 5. Dreams act at an early period upon the bodies of children. Their fmiles, flartings, and occasion- al Screams in their fleep appear to ariSe from them. After the third or fourth year of their lives, they fometimes confound them with things that are real. From obferving the effects of this mistake upon the memory, a fenfible woman whom I once knew, for- bad her children to tell their dreams, left they fhould contract habits of lying, by confounding imaginary, with real events. 6. New ANIMAL LIFE. 39 6. New objects whether natural or artificial, are never feen by children without emotions of pleafure which act upon their capacity of life. The effects of novelty upon the tender bodies of children may eafily be conceived, by its Sriendly influence upon the health of invalids who vifit foreign countries, and who pafs months, or years in a constant fucceflion of new and agreeable im- preffions. III. From the combination of all the Stimuli that have been enumerated, human life is generally in excess from fifteen to thirty-five. It is during this period, the paflions blow a perpetual florm. The most predominating of them is the love of pleafure. No fooner does the fyftem become infenfible to this ftimulus, than ambition fucceeds it in, IV. The middle stage of life. Here we behold man in his most perfect physical State. The Stimuli which now act upon him are So far regulated by prudence, that they are Seldom exceffive in their force. The habits of order the fyftem acquires in this period, continue to produce good health for many years afterwards, and hence bills of mortality prove that fewer perfons die between forty and fifty-feven; than in any other feventeen years of human life. V. In 40 LECTURES ON V. In old age the fenfes of feeing, hearing and touch are impaired. The venereal appetite is weakened, or entirely extinguifhed. The pulfe becomes flow, and fubject to frequent intermiflions, from a decay in the force of the blood veffels; Exercife becomes impracticable, or irkfome, and the operations of the underftanding are performed with languor and difficulty. In this fhattered and declining ftate of the fyftem, the abfence and diminution of all the stimuli which have been mentioned are Supplied, i. By an increaSe in the quantity, and by the pe- culiar quality of the food which is taken by old people. They generally eat twice as much as per- fons in middle life, and they bear with pain the ufual intervals between meals. They moreover prefer that kind of food which is Savoury and ftimulating. The ftomach of the celebrated Parr, who died in the one hundred and fiftieth year of his age, was found full of strong, nourifhing ali- ment. 2. By the Stimulus of the faeces which are fre- quently retained for five or fix days in the bowels of old people. 3- By ANIMAL LIFE. 4* 3. By the stimulus of fluids rendered preterna- turally acrid by age. The urine, Sweat and even the tears of old people, poflefs a peculiar acrimo- ny. Their blood likeWiSe loSes part of the mild- ness which is natural to that fluid ; and hence the difficulty with which fores heal in old people; and hence too the reafon why cancers are more com- mon in the decline, than in any other period of human life. 4. By the uncommon activity of certain paffions. Thefe are either good or evil. To the former be- long an increafed vigor in the operations of thofe paffions which have for their objects the Divine Being, or the whole family of mankind, or their own offspring, particularly their grand-children. To the latter paffions belong, malice, a hatred of the manners and fafhions of the rising generation, and above all, avarice. This paffion knows no holidays. Its stimulus is constant, though varied daily by the numerous means which it has discover- ed of increafing, Securing, and perpetuating pro- perty. It has been obServed that weak mental impreffions produce much greater effects in old people than in perfons in middle life. A trifling indiSpofition in a grand-child, an inadvertent act of unkindnefs Srom a friend, or the Sear of losing ;i few Shillings, have in many instances produced G in 42 LECTURES ON m them a degree of wakefulness that has continued for two or three nights. It is to this highly exci- table State of the fyftem that Solomon probably al- ludes, when he defcribes the grafshopper as bur- denSome to old people. 5. By the paffion for talking, which is fo com- mon, as to be one of the characteristics oS old age. I mentioned formerly, the influence of this ftimulus upon animal life. Perhaps it is more neceflary in the female constitution than in the male; for it has long ago been remarked, that women who are ve- ry taciturn, are generally unhealthy. 6. By their wearing warmer clothes, and prefer- ring warmer rooms, than in the former periods of their lives. This practice is fo uniform, that it would not be difficult in many cafes to tell a man's age by his drefs, or by finding out at what degree of heat he found himfelf comfortable in a clofe room. 7. By dreams. Thefe are univerfal among old people. They ariSe from their Short and imperfect fleep. 8. It has been often Said that " We are once men, and twice children." In Speaking of the State of animal ANIMAL LIFE. 43 animal life in infancy, I remarked that the contrac- tility of the animal fibres, predominated over their fenfibility in that ftage of life. The fame thing takes place in old people, and it is in confequence of the return of this infantile ftate oS the System, that all the ftimuli which have been mentioned act upon them with much more force than in middle life. This SameneSs, in the predominance oS excita- bility over Senfibility in children and old people, will account for the Similarity of their habits with refpect to eating, fleep, exerciSe, and the uSe of fermented or distilled liquors. It is from the in- creafe of excitability in old people, that fo fmall a quantity of strong drink intoxicates them ; and it is from an ignorance of this change in their constitu- tions, that many of them become drunkards after passing the early and middle ftages of life with fober characters. Life is continued in a lefs imperfect State in old age, in women than in men. The Sormer Sew, and knit, and Spin, after they lofe the ufe of their ears and eyes; whereas the latter, after losing the ufe of thofe fenfes, frequently pafs the evening oS their lives in a torpid ftate in a chimney corner. It is Srom the influence of moderate and gently Sti- mulating employments, upon the female constitu- tion, that more women live to be old, than men, and 44 LECTURES ON and that they rarely Survive their uSefulnefs in. domestic life. Hitherto the principles I am endeavouring to eftablifh, have been applied to explain the cauSe of life in its more common forms. Let us next inquire, how far they will enable us to explain its continuance in certain morbid ftates of the body, in which there is a diminution of fome, and an appa- rent abstraction of all the ftimuli, which have been fuppofed to produce animal life. I. We obferve fome people to be blind, or deaf and dumb from their birth. The fame defects of fight, hearing, and fpeech, are fometimes brought on by difeaSes. Here animal life is de- prived oS all ihofe numerous ftimuli, which arife Srom light, colors, Sounds, and Speech. But the ab- sence of thefe ftimuli is Supplied, i. By increaSed fenfibility and excitability in their remaining fenfes. The ears, the nofe, and the fingers, afford a Surface for impreffions in blind people which frequently overbalances the lofs of their eyefight. There are two blind young men, brothers, in this city, of the name of Dutton, who can tell when they approach a post in walking acrofs a Street, by a peculiar Sound which the ground under animal life; 45 under their feet emits in the neighbourhood of the post. Their fenfe of hearing is Still more exquisite to Sounds of another kind. They can tell the names of a number of tame pidgeons, with which they amufe themSelves in a little garden, by only hear- ing them fly over their heads. The celebrated blind philoSopher Dr. MoySe can distinguish a black dreSs on his friends, by its fmell; and we read of many instances of blind perfons who have been able to perceive colors by rubbing their fingers up- on them. One of thefe perfons mentioned by Mr. Boyle, has left upon record an account of the Speci- fic quality of each color as it affected his fenfe of touch. He fays, black imparted the moll, and blue, the least perceptible fenfe of afperity to his fingers. 2. By an increafe of vigor in the exercifes of the mental faculties. The poems of Homer, Mil- ton and Blacklock, and the attainments of Sander- fon in mathematical knowledge, all difcover how much the energy of the mind is increafed by the abfence of impreffions upon the organs of vifion. II. We Sometimes behold life in idiots in whom there is not only an abfence of the stimuli of the understanding and paflions; but frequently from the weaknefs of their bodies, a deficiency of the loco- motive 46 LECTURES ON motive powers. Here an inordinate appetite for food, or venereal pleafures, or a conftant.habit of laughing, or talking, or playing with their hands and feet, fupply the place of the stimulating ope- rations of the mind, and of general bodily exercife. Of the inordinate force of the venereal appetite in idiots we have many proofs. The Cretins are much fc addicted to venery ; and Dr. Michaelis tells us that the idiot whom he Saw at the PeSaiac Sails in New- JerSey, who had paffed fix and twenty years ifi a cradle, acknowledged that he had venereal defires, and wifhed to be married, for the Doctor adds, he had a fenfe of religion upon his fragment of mind, and of courfe did not wifli to gratify that appetite in an unlawful manner. III. How is animal life fupported in perfons who pafs many days, and even weeks without food, and in Some inflances without drinks ? Long fad- ing is usually the effect of difeafe, of necessity, or of a principle of religion. When it arifes from the firfl caufe, the actions of life are kept up by the stimulus of difeafe. The abSence oS Sood when accidental, or fubmitted to as a means of producing moral happinefs, is Supplied, 1. By the flimulus of a full gall bladder. This State of the receptacle of bile, has generally been found ANIMAL LIFE/ 47 found to accompany an empty ftomach. The bile is Sometimes abSorbed, and imparts a yellow co- lor to the fkin of perfons who Suffer or die of famine. 2. By increafed acrimony in all the fecretions and excretions of the body. The Saliva becomes So acrid by long Sailing, as to excoriate the gums, and the breath acquires not only a Sector, but a pungency So active, as to draw tears from the eyes of perfons who are expofed to it. 3. By increafed fenfibility and excitability in the fenfe of touch. The blind man mentioned by Mr. Boyle who could distinguish colors by his fingers, polfeffed this talent only after fasting. Even a draught of any kind of liquor deprived him of it. I have taken notice in my account of the yellow fever in Philadelphia in the year 1793, of the effects of a diet bordering upon fafling for fix weeks, in producing a quicknefs and correct- ness in my perceptions of the Slate of the pulfe, which I had never experienced before. 4. By an increafe of activity in the under- standing and paffions. Gamesters often improve the exercifes of their minds when they are about to play for a large fum of money, by living for a day 48 LECTURES ON day or two upon roasted apples and cold water. Where the paffions are excited into preternatural action, the abfence of the flimulus of food is fcarcely felt. I fhall hereafter mention the influ- ence of the defire of life, upon its prefervation under all circumstances. It acts with peculiar force when fasting is accidental. But when it is fubmitted to as a religious duty, it is accompanied by fentiments and feelings which more than ba- lance the abstraction of aliment. The body of Mofes was Sustained, probably without a miracle, during an abstinence of forty days and forty nights, by the pleafure he derived from converf- ing with his Maker " Face to face, as a man Speak- ing with his friend."* I remarked formerly that the veins diScover no deficiency of blood in perfons who die of famine. „ Death from this caufe feems to be lefs the effect of the want of food, than of the combined and excef- five operation of the stimuli, which fupply its place in the fyftem. IV. We come now to a difficult inquiry, and that is, how is life fupported during the total ab- straction of external and internal stimuli which takes * Exodv.:, xxxiii. II. xxxiv. 28. ANIMAL LIFE. 49 takes place in - afphixia, or in apparent death, from all its numerous caufes ? I took notice in a former lecture, that ordinary life confuted in the excitement, and excitability of the different parts of the body ; and that they were occasionally changed into each other. In apparent death from violent emotions of the mind, from the sudden impreffion of miafmata, or from drowning, there is a lofs of excitement; but the excitability of the fyftem remains for minutes, and in fome in* fiances for hours afterwards unimpaired, provided the accident which produced the lofs of excite- ment has not been attended with Such exertions as are calculated to waste it. If for example, a per- fon fhould fall fuddenly into the water, without bruifing his body, and fink before his fears, or exertions had time to diffipate his excitability ; his recovery Srom apparent death might be effected by the gentle action of heat, or frictions upon his body, fo as to convert his accumulated excitability gradually into excitement. The fame condition of the fyftem takes place when apparent death oc- curs from freezing, and a recovery is accomplifhed by the fame gentle application of ftimuli, provided the organization of the body be not injured, or its excitability wasted, by violent exertions previ- ously to its freezing. This excitability is the II vehicle 50 LECTURES ON vehicle of motion, and motion when continued long enough produces fenfation, which is foon fol- lowed by thought; and in thefe, I Said formerly, consists perfect life in the human body. For this explanation of the manner in which life is fufpended, and revived in perfons apparently dead from cold, I am indebted to Mr. John Hun- ter, who fuppofes, if it were poffible for the body to be fuddenly frozen by an instantaneous abstracti- on of its heat, life might be continued for many years in a fufpended ftate, and revived at pleafure ; provided the body were preferved constantly in a temperature barely fufficient to prevent reanima- tion, and never fo great," as to endanger the de- struction of any organic part. The refufcitation of infects that have been in a torpid ftate for months, and perhaps years, in Substances that have preServed their organization, Should at least defend this bold proposition from being treated as chimerical. The effufions even of the imagination of fuch men as Mr. Hunter, are entitled to re- Spect. They often become the germs of future difcoveries. In that State of fufpended animation which oc- curs in acute difeafes, and which has fometimes been denominated a trance ; the fyftem is nearly in the ANIMAL LIFE. $1 the fame excitable State that it is in apparent death Srom drowning, and freezing. Refufcitation in thefe cafes is not the effect as in thofe which have been mentioned of artificial applications made to the body for that purpofe. It appears to be Spon- taneous ; but it is produced by impreffions made upon the ears, and by the operations of the mind in dreams. Of the action of thefe ftimuli upon the body in its apparently lifelefs Slate, I have Satisfied mySelS by many facts. I once attended a' citizen of Philadelphia, who died of a pulmonary difeafe in the 8oth year of his age. A few days before his death he begged that he might not be interred until one week after the ufual figns of life had left his body, and gave as a reafon for this requeft, that he had when a young man, died to all appearance of the yellow fever in one of the Weft-India iflands.—In this Situation he distinctly heard the perSons who attended him, fix upon the time, and place, of burying him. The horror of being put under ground alive, produced fuch dif- treffing emotions in his mind, as to diffufe motion throughout his body, and finally excited in him all the ufual functions of life. In Dr. Creighton's effay upon mental derangement there is a history oS a caSe nearly oS a Similar nature. " A young lady (Says the DoctorJ an attendant on the princeSs oS-----, aSter having been confined to her bed for 52 LECTURES ON for a great length of time, with a violent nervous diforder, was at last, to all appearance, deprived of life. Her lips were quite pale, her face refem- '* bled the countenance of a dead perfon, and her body grew cold. She was removed from the room in which Jhe died, was laid in a coffin, and the day for her funeral was fixed on. The day arrived, and according to the custom of the country, fu- neral fongs and hymns were Sung before the door. Jufl as the people were about to nail on the lid of the coffin, a kind of perfpiration was obferved on the furface of her body. She recovered. The following is the account She gave of her fenfations ; flie Said, " It Seemed to her as if in a dream, that. fhe was really dead; yet She was perfectly confci- ous of all that happened around her. She dis- tinctly heard her friends Speaking and lamenting her death at the fide of her coffin. She felt them pull on the dead clothes, and lay her in it. This feeling produced a mental anxiety which fhe could not defcribe. She tried to cry out, but her mind was without power, and could not act on her body. She had the contradictory feeling as if fhe were in her own body, and not in it, at the fame time. It was equally impossible Sor her to Stretch out her arm or open her eyes, as to cry, although fhe continually endeavoured to do So. The inter- nal anguifh of her mind was at its utmofl height when ANIMAL LIFE. ^^ When the funeral hymns began to be fung, and when the lid of the coffin was about to be nailed on. The thought that fhe was to be buried alive was the first which gave activity to her mind, and enabled it to operate on her corporeal frame." Where the ears lofe their capacity of being act- ed upon by Stimuli, the mind by its operations in dreams, becomes a fource of impreffions which again fet the wheels of life in motion. There is an account publifhed by Dr. Arnold in his obser- vations upon insanity,* oS a certain John Engel- breght a German, who was believed to be dead, and who was' evidently reSuScitated by the exerciSes of his mind upon fubjects which were of a delight- ful and Stimulating nature. This history fliall be taken Srom Mr. Engelbreght's words. " It was on ThurSday noon (Says he) about 12 o'clock when I perceived that death was making his approaches upon me from the lower parts upwards, infomuch that my whole body became Stiff. I had no feel- ing left in my hands and feet, neither in any other part of my whole body, nor was I at last able to fpeak or fee, for my mouth now becoming very stiff, I was no longer able to open it, nor did I feel it any longer. My eyes alfo broke in my head * Vol. ii. f. 29S. ' 54 LECTURES ON head in fuch a manner that I distinctly felt it. For all that, I understood what they Said, when they were praying by me, and I distinctly heard them Say, feel his legs, how Stiff, and cold they have become. This I heard distinctly, but I had* no perception of their touch. I heard the watchman cry 11 o'clock, but at 12 o'clock my hearing left me. After relating his paffage from the body to heaven with the velocity of an arrow fliot from a croSs bow, he proceeds, and Says that as he was twelve hours in dying, So he was twelve hours in returning to life. " As I died (Says he) Srom be- neath upwards, So I revived again the contrary way Srom above to beneath, or from top to toe. Being conveyed back from the heavenly glory, I began to hear again fomething of what they were praying for me, in the fame room with me. Thus was my hearing, the first fenfe I recovered. Af- ter this I began to Jhave a perception of my eyes, fo that by little and little, my whole body became' ftrong, and fprightly, and no fooner did I get a feeling of my legs and feet, than I arofe and flood firm upon them with a firmness I had never enjoy- ed before. The heavenly joy I had experienced, invigorated me to Such a degree, that people were astonished at my rapid, and almost instantaneous recovery." The ANIMAL LIFE. 55 The explanation, I have given of the caufe of re- fufcitation in this man, will ferve to refute a belief in a fuppofed migration of the foul from the body in cafes of apparent death. The imagination, it is true, usually conducts the whole mind .to the abodes of happy or miferable Spirits, but it acts here in the Same way that it does when it trans- ports it in common dreams, to numerous and diS- tant parts of the world. There is nothing supernatural in Mr. Engel- breght being invigorated by his SuppoSed flight to heaven. Pleafant dreams always Stimulate and Strengthen the body, while dreams which are ac- companied with diftreSs, or labour debilitate, and fatigue it. LECTURE III. Gentlemen, Let us next take a view of the ftate of animal life in the different inhabitants of our globe, as varied by the circumftances of civilization, diet, fituation and climate. I. In 56 LECTURES ON I. In the Indians of the northern latitudes of America, there is often a defect of the stimulus of aliment, and of the underftanding and paffions. Their vacant countenances, and their long and diS- gufting taciturnity, are the effects of the want of action in their brains from a deficiency of ideas; and their tranquillity under all the common cir- cumftances of irritation, pleaSure or grief, are the refult of an abfence of paffion ; for they hold it to be difgraceful to fhew any outward figns of anger, joy, or even of domestic affection. This account of the Indian character, I know is con- trary to that which is given of it by Rouffeau, and Several other writers, who have attempted to prove that man may become perfect and happy, without the aids of civilization and religion. This opi- nion is contradicted by the experience of all ages, and is rendered ridiculous by the facts which are well afcertained in the history of the cufloms and habits of our American favages. In a cold climate they are the mofl miferable beings upon the face of the earth. The greatest part of their time is Spent in fleep, or under the alternate influence of hunger and gluttony. They moreover indulge in vices which are alike contrary to moral and physical happiness. It is in confequence of thefe habits, that they difcover fo early the marks of old age, and that fo few of them are long-lived. The abfence ANIMAL LIFE. 57 abfence and diminution of many of the ftimuli of life in thefe people is fupplied in part, by the via. lent exertions with which they hunt, and carry on war, and by the extravagant manner with which they afterwards celebrate their exploits, in their Savage dances and Songs. II. In the inhabitants of the torrid regions of Africa, there is a deficiency of labor; for the earth produces fpontaneoufly nearly all the Suste- nance they require. Their understandings and pafc fions are moreover in a torpid State. But the abSence oS bodily and mental Stimuli in theSe people, is amply Supplied by the conftant heat of the fun, by the profufe ufe of fpices in their diet, and by the passion for musical Sounds which So universally characterises the African nations. III. In Greenland the body is expofed during a long winter to Such a degree of cold as to re- duce the pulfe to 40, or 50 Strokes in a minute. But the effects of this cold in leffening the quantity of life, are obviated in part by the heat of clofe flove rooms, by warm clothing, and by the pecu- liar nature of the aliment of the Greenlanders, which consists chiefly of animal food, of dried fifh, and of whale oil. They prefer the laft of thofe articles in fo rancid a ftate, that it imparts a I fa? tor 58 LECTURES ON fastor to their perfpiration which, Mr. Crantz fays* renders even their churches offenfive to strangers. I need hardly add, that a diet poireffed of Such diffusible qualities, cannot fail of being highly fti- mulating. It is remarkable that the food of all the northern nations of Europe is compofed of ftimulating animal, or vegetable matters,, and that the uSe of fpiritous liquors is universal among them. IV. Let us next turn our eyes to the miserable inhabitants oS thoSe eastern countries which compoSe the Ottoman empire. Here we behold life in its most reeble State, not only Srom the abSence of phyfical, but of other stimuli which operate upon the inhabitants of other parts of the world. Among the poor people of Turkey there is a general deficiency of aliment. Mr. Volney in his travels tells us " That the diet of the Bedouins- feldom exceeds fix ounces a day, and that it con- fifts of fix or feyen* dates foaked in butter-milk, and afterwards mixed with a little fweet milk, or curds."—There is likewife a general deficiency among them of flimulus, from the operations of the mental faculties; for fuch is the defpotifm of the government in Turkey, that it weakens not only the understanding; but it annihilates all that immenfe fource of ftimuli which arifes from the exercife of the domestic and public affections. A Turk ANIMAL LIFE. 59 Turk lives wholly to himfelf. In point of time, he occupies only the moment in which he exists; for his futurity, as to life and property, belongs altogether to his master. Fear is the reigning principle- of his actions, and hope and joy feldom add a single pulfation to his heart. Tyranny even impofes a restraint upon the ftimulus which arifes from conversation, for " They fpeak (fays Mr. Vol- ney) with a flow feeble voice, as if the lungs wanted ftrength to propel air enough through the glottis to form distinct articulate Sounds." The fame traveller adds, that " They are flow in all their motions, that their bodies are fmall, that they have fmall evacuations, and that their blood is fo deftitute of ferofity, that nothing but the greatest heat can preServe its fluidity." The defi- ciency, of aliment, and the abfence of mental fti- muli in thefe people is fupplied, i. By the heat of their climate. 2. By their paifion for mufical founds and fine clothes, and 3. By their general ufe of coffee and opiinn. The more debilitated the body is, the more forcibly thefe stimuli act upon it. Hence accord- ing 60 LECTURES ON ing to Mr. Volney, the Bedouins, whofe flcnder diet has been mentioned, enjoy good health; for this consists not in Strength, but in an exact proportion being kept up between the excitability of the body, and the number and force of the ftimuli which act upon it. V. Many of the obfervations which have been made upon the inhabitants of Africa, and of the Turkifh dominions, apply to the inhabitants of China, and the East Indies, They want in many instances the Stimulus of animal food. Their minds are moreover in a ftate too languid to act with much force upon their bodies. The abfence and deficiency of thefe stimuli are Supplied by, i. The heat of the climate in the fouthern parts of thofe countries. 2. By a vegetable diet abounding in nourifh- ment, particularly rice and beans. 3. By the ufe of tea in China, and by a ftimu- lating coffee made of the dried and toasted feeds of the datura stramonium, in the neighbourhood of the Indian coast. Some of thefe nations likewife chew ftimulating fubflances, as too many of our dtizens do tobacco. Among ANIMAL LIFE. 6.1 Among the poor and depreffed subjects of the governments of the middle and fouthern parts of Europe, the deficiency of the ftimulus of whole- fome food, of clothing, of fuel, and of liberty, is Supplied in Some countries by the invigorating influence of the Chriflian religion upon animal life; and in others, by the general ufe of tea, coffee, garlic, onions, opium, tobacco, malt liquors, and ardent fpirits. The ufe of each of thefe ftimuli feems to be regulated by the circumftances of cli- mate. In cold countries where the earth yields its increafe with reluctance, and where vegetable ali- ment is fcarce, the want of the ftimulus of disten- tion which that Species of food is principally calcu- lated to produce, is fought for in that, of ardent fpirits. To the fouthward of 400 a fubftitute for the distention from mild vegetable food is fought for, in onions, garlic and tobacco. But further, a uniform climate calls for more of thefe artificial fti- muli than a climate that is expofed to the alternate action of heat and cold, winds and calms, and of wet and dry weather. Savages and ignorant people likewife require more of them than perfons of civilized manners, and cultivated underftandings. It would feem from thefe facts that man cannot ex- ist without fenfation of fome kind, and that when it is not derived from natural means, it will always be fought for in fuch as are artificial. In 6l LECTURES ON In no part of the human fpecies, is animal life in a more perfect ftate than in the inhabitants of Great Britain,* and the United States of America. With all the natural ftimuli that have been menti- oned, they are constantly under the invigorating influence of liberty. There is an indiffoluble uni- on between moral, political and physical happi- neSs; and if it be true, that elective and reprefen- tative governments are rhofl favourable to indivi- dual, as well as national profperity, it follows of courfe, that they are most favourable to animal life. But this opinion does not reft upon an induc- tion derived from the relation, which truths up- on all Subjects bear to each other. Many facts prove, animal life to exist in a larger quantity and for a longer time, in the enlightened and happy ftate of Connecticut, in which republican liberty has existed above one hundred and fifty years, than in any other country upon the furface of the globe. It remains now to mention certain mental ftimuli which act nearly alike in the production of animal life, upon the individuals of all the nations in the world. They are, i. The defireof life. This principle fo deeply, and univerfally implanted in human nature, acts very * Haller's Elementa Phyfiologiz, vol. viii. p. 2. p. 107. ANIMAL LIFE. 6$ very powerfully in Supporting our existence. It has been obServed to prolong life. Sickly tra- vellers by fea and land, often live under circum- ftances of the greatest weakneSs, till they reach their native country, and then expire in the bo- Som of their friends. This defire of life often turns the fcale in favor of a recovery in acute difeafes. Its influence will appear, from the difference in the periods in which death was induced in two per- fons, who were actuated by oppofite paflions with refpect to fife. Atticus, we are told, died of volun- tary abstinence from food in five days. In Sir Wil- liam Hamilton's account of the earthquake at Cala- bria, we read of a girl who lived eleven days without food, before fhe expired. In the former cafe, life was fhortened by an aversion from it; in the latter, it was protracted by the defire of it. The late Mr. Briffot in his vifit to this city, informed mc that the application of animal magnetifm (in which he was a believer) had in no instance cured a dif- eafe in a Weft India flave. Perhaps it was ren- dered inert by its not being accompanied by a strong defire of life ; for this principle exists in a more feeble ftate in flaves than in freemen. It is poffible likewiSe the wills and imaginations of thefe degraded people may have become fo paralytic by flavery, as to be incapable of being excited by the impreffion of this fanciful remedy. 2. The 64 LECTURES ON 2. The love of money fets the whole animal machine in motion. Hearts which are infenfible to the ftimuli of religion, patriotifm, love, and even of the domestic affections, are excited into action by this paffion. The city of Philadelphia between the 10th and 15th of August 1791, will long be remembered by contemplative men, for having furnifhed the most extraordinary proofs of the ftimulus of the love of money upon the hu- man body. A new fcene of fpeculation was pro- duced at that time by the fcrip of the bank of the United ftates. It excited febrile difeafes in three perfons who became my patients. In one of them, the acquisition of twelve thousand dollars in a few minutes by a lucky Sale, brought on madneSs which terminated in death in a Sew days.* The whole city Selt the impulSe of this paroxyfm of avarice. The flow and ordinary means of earning money were deferted, and men of every profeffion and trade, were feen in all our Streets hastening to the coffee houfe, where the agitation of countenance, and the desultory manners, of all the perfons who were interested in this Species of gaming, exhibited a truer picture of a bedlam, than of a place * Dr. Mead relates upon the authority of Dr. Hales, that more of the fuccefsful fpcculitors in the South Sea Scheme of 1720 became infane, than of thofe who had been ruined by it. ANIMAL LIFE* 65 a place appropriated to the transaction of mer- cantile bufinefs. But further, the love of money difcovers its ftimulus upon the body in a peculiar manner in the games of cards and dice. I have heard of a gentleman in Virginia who paffed two whole days and nights in fucceffion at a card table, and it is related in the life of a noted game- ster in Ireland, that when he was So ill as to be unable to riSe from his chair, he would fuddenly revive when brought to the hazard table, by - hearing the rattling of the dice. 3. Public amufements of all kinds, fuch as a horfe race, a cockpit, a chafe, the theatre, the circus, mafquerades, public dinners and tea par- ties, all exert an artificial flimulus upon the fyftem, and thus fupply the defect of the rational exercifes of the mind. 4. The love of drefs is not confined in its ftimulating operation to perfons in health. It acts perceptibly in fome cafes upon invalids. I have heard of a gentleman in South Carolina, who always relieved himfelf of a fit of low fpirits by chang- ing his drefs; and I believe there are few people who do not feel themfelves enlivened, by putting on a new Suit of clothes. K 5. Novelty 66 LECTURES ON 5. Novelty is an immenfe fource of agreeable ftimuli. Companions, Studies, pleaSures, modes of bufinefs, profpects, and Situations with refpect to town, and country, or to different countries, that are new, all exert an invigorating influence upon health and life. 6. The love of fame acts in various ways; but its flimulus is most fenfible and durable in military life. It counteracts in many instances the debilitat- ing effects of hunger, cold and labor. It has fome- times done more, by removing the weaknefs which is connected with many difeafes. In feveral in- stances it has affifled the hardfhips of a camp life, in curing pulmonary consumption. 7. The love of country is a deep feated principle of action in the human breafl. Its ftimulus is Some- times So exceffive, as to induce diSeaSe in perSons who recently migrate, and Settle in S01 "ign coun- tries.—It appears in various forms; but exists moft frequently in the folicitude, labors, attachments, and hatred of party Spirit. All theSe act forcibly in fupporting animal life. It is becaufe newspapers are fuppofed to contain the meafure of the happi- ness, or miSery of our country, that they are fo in- teresting to all claffes of people. Thofe vehicles of intelligence, and of public pleafure or pain, are frequently ANIMAL LIFE.