•tf%? J&&P ?%%# ^'-t»:'^ % ■■*: ■&%;>* m Ci?, .v#P .^ ^*s fc ;^ :#.& LlA y&. By JOHN HAHN, V,rV \w J - ^ f^v^^ OF PENNSYLVANIA, -^* . / Honorary Member of the' Philadelphia Medical and Chemical Societies. PHILADELPHIA: PRINTED BY STEPHEN C USTICK, 1798. TO CASPAR WISTAR, m. d. ADJUNCT PROFESSOR OF ANATOMY, SURGERY, AND MIDWIFERY, UN I VERS ITT OF PENNSYLVANIA ; THIS DISSERTATION IS DEDICATED, AS A SMALL TRIBUTE OF RESPECT, FOR THE MANY ADVANTAGES AND ATTENTIONS RECEIVED DURING THE STUDIES OF HIS FRIEND AND PUPIL, The AUTHOR. OBSERVATIONS and EXPERIMENTS ON THE USE OF ENEMATA, &c. .ATthecomffie„ofanE%upona fubject. in which the Lymphatic VefTels are particu- larly concerned, it may not be improper to give a general view of that fyftem; this I mall do in as concife a manner as poffible. CHAPTER I. Of the Absorbe?it System. A. HAT procefs in the Animal Body which. is called Abforption, is performed by a (ct of vefTels peculiarly appropriated to the purpofe, and not as the ancients fuppofed by the veins: the vefTels per- forming this function, are at prefent known by two names ; thofe fituated in the abdomen, and paiiing immediately from the inteflines, have, from their B 4 carrying the fluid called chyle, which fomewhat refembles milk, been called lafteals. Thofe abfor- bents which originate from the external furface, and other parts of the body, have been denominated Lymphatics; although thefe vefTels have been dif- tinguifhed by different names, they are the fame in their ftructure and functions. The lymphatics equal the arteries in their minute and univerfal diftribution; there is no part of the animal body, be it ever fo fnaall or ever fo remotely fituated, without the power of abforption. We may apply a fluid to any part of the external furface, and it will be abforbed; the innumerable examples afforded us by the abforption of the water of dropfy, of matter from internal ulcers and cavities, and alfo of the moft folid parts, in every fituation, proves not only the univerfal diftribution, but like- wife the great power of this fun&ion in the animal ceconomy. There is, we may fafely fay, no power in the animal machine more neceffary to its exiftence than abforption : it is commonly faid that we cannot exift without the circulation, or the nervous influ- ence exerted on the body; we may with the fame propriety fay that an animal cannot exift without the power of abforption ; for if the performance of this fun&ion was wanting, circulation would foon ceafe, and without the a&ion of the heart and arte- ries the powers of the brain would immediately be deftroyed. The lymphatic vefTels are in general fo fmall, that their mouths opening on the different fu:-faces cannot 5 be feerr"by the naked eye; this minute fize has prevented their ftructure from being fo much unra- velled as that of the arteries and veins; it is however certain that they refemble them in fome refpe&s. Several experiments and obfervations have been made in proof of the nrufcularity of the abforbent vefTels. Nuck andCruikfhank have both feen and demon- ftrated fibres in the thoracic duel: of horfes; the latter Of thefe gentlemen obferves, that he has feen fibres in a human thoracic duct. Thefe obfervations prove that the great lymphatic duel:, and perhaps fome of the larger branches of thefe vefTels have fibres, but O every fubftance that is fibrous cannot with propriety be faid to be mufcular. The beft teft we have. of mufcularity, fays Mr. Cruikfhank, " is the difpo- fition in a part to contract on the application of ftimuli;" this our author found to be the cafe with the abforbents, and it generally has been concluded, from thefe and other obfervations, that lymphatics are mufcular. That lymphatics have confiderable ftrength, even in the dead body, appears from their fupporting no fmall weight when injected with mercury j I have feen a large number of vefTels fituaced on the leg and thigh fufpended by a few branches when all were injected with that fluid. With regard to the fenfibility and vafcularity of lymphatics little doubt remains; analogical reafoning would lead us to conclude: that they poffefs both nerves and blood veffel?, and in addition to this, 6 experiment and accidental occurrences prove the fame thing. The fenfibility of lymphatics is fufficiently demon- ftrated by their taking on a preternatural action upon the application of a ftrong ftimulus. Abforbents have not unfrequently been feen in aftate of inflammation, after fome active poifon has been circulating in them; from our prefent knowledge and theory of inflam- mation, we conclude that it cannot take place where there are no vefTels, this then I truft may be coh- fidered as a fufficient teft of the vafcularity of lymphatics. Abforbent vefTels, like veins, are furnifhed with valves, which in fome parts are fo numerous, that half a dozen may be met with in a portion of the veffel not more than an inch in length •, thefe valves are fo formed and fituated that they admirably prevent a retrograde direction of the fluid palling in their refpective vefTels; their figure is femilunar, they are placed in pairs, one oppofite the other, with their convex edges attached to the veffel, and they play like moveable partitions ; when the fluid paffes in a natural direction they lay clofe againft the fides of the veffel ; on the contrary, when the fluid is forced in a retrograde courfe, their loofe edges leave the fides of the veffel, meet each other in the middle, and thus prevent any further progrefs of it. Valves, fuch as have been defcribed, are uniformly fituated at the entrance of the abforbent veffels into the thoracic duct, and where this great refervoir of the lymphatic fluid joins the left fubclavian vein. f The manner in which the abforbents take up fluids from the furfaces of the body remains as yet undetermined by Phyfiologifts; on this difficult queftion I fhall not-prefume to decide, but leave it for abler minds than mine to determine. After the fluid has entered the veffel a fhort diftance, its motion depends upon caufes fimilar to thofe of the motion of the blood in the veins, viz. partly upon the preffure received from the contracted mufcles and pulfating arteries, and partly upon the action of the lymyhatic vefTels themfelves. Here the great ufe of the valves in thefe vefTels is made evident; when the veffel is preffed by the fwelling of the adjacent mufcles in a ftate of contraction, if it were not for thefe valves, the fluid would as readily take on a retrograde, as a forward direction, but with this provifion it muft purfue a natural courfe. Abforbents, like veins, run from the circumference towards the centre ; they originate from every part of the body, pafs in every direction, frequently anaftomofing and forming net-works, and laftly, are collected in one great trunk called the thoracic duct; this enters into the left fubclavian vein ; fometimes thefe are two ducts, one entering into the left, the other into the right fubclavian. The lymphatic glands are numerous, and varioufly diftributed : we find them moft abundant, in the o-roins, axilla?, the mefentary, and about the root of the lungs. After a long inveftigation of the ftructure and nature of thefe glands, by many different anato- mifts, little more of their ufe is known now than at 8 their firft difcovery ; although we know fo little of their functions, there can be no doubt but that they are a neceffary appendage to the lymphatic fyftem, and the difcovery of their ufe in the animal ceconomy may one day or other throw great light on fome difcoveries, with which we are at prefent but little acquainted. After having thus briefly confidered the ftructure, diftribution;, and courfe of the lymphatic vefTels, I am led to make a few obfervations on their ufe in fupporting animal life. The food of animals, after it is received into the ftomach and inteftines, is fubjected to the procefs of digeftion, and the nutritive parts thereof are con- verted into chyle. It ;s the office of the abforbents of the inteftines or lacteals to convey the chyle thus formed into the general circulation. But this is not the only office of the lymphatics; in cafe no aliment is taken into the ftomach, or when food taken m is not digefted, in fhort, where no chyle is formed in the alimentary canal, be it from whatever caufe, they can fupport life for fome time by abforbing from the atmofphere, from the adipofe membrane, or from any part where they meet a fluid proper for entering the general circulation. Hybernating animals afford a ftriking example of the laft mentioned power of the abforbents. The bear when he enters his cave in the autumn, is loaded with adeps, he ceafes to eat, no more chyle is formed in his alimentary canal, the lymphatics now begin to devour the fat which had been ftored up during the fummer; in this manner 9 he lives as it were upon his own flefh during the whole winter. The lymphatic veffels are not equally diftributed through every part of the body, fome parts are endowed with a number far greater than others. The fmall inteftines from their being the natural organs of nourifhment, have perhaps a greater num- ber of abforbents fcattered on their furface, than any other equal part of the body. The large inteftines are not without the power of abforption, as will appear not only from the cafe prefently to be related, but alfo from the reports of anatomifts. For example : In Fleming's Phyfiology, p. 249, we find the following diffection quoted from Dr. Swenke : " A fojdier was killed by a muiket fhot foon after eating a plentiful meal, the bullet deftroyed the clavicle with the veffels under it, whereby the thoracic duct, near its infertion into the left fubclavian was compreffed, and th? paffage of chyle through it flopped. Upon opening the dead body, innumerable lacteals appeared through the whole extent of the colon, to its termination in the pelvis j" from this he very properly inferred the utility of nutritive enemata. • The defcriptions of the lymphatics of the large inteftines which are to be found in the works of thofe accurate inveftigators, Mafcagni apd Cruikfhaiik. confirm this account of Dr. Swenke. * 10 CHAPTER II. Of the Absorbing Power of the great Intestines, and the consequent Utility of Enemata. J? ROM the anatomical ftructure of the large inteftines, we might conclude that they poffeffed great powers of abforption, but the following facts are directly in proof of it, and fhow the great advantages to be derived from nutritive injections into thefe inteftines, in cafes of ftarvation from whatever caufe. The firft cafe to be related is one that came under my immediate infpection. John Fifher, aged 21 years, was admitted a patient in the Alms-Houfe, with a protracted inflam- matory fever, for which he took powders of nitre and calomel; in a few days his mouth was affected by the mercury, and in confequence of a fudden application of cold, his parotid glands, neckj and face, became fo much fwelled, that he was unable to take in any folid food ; in this fituation he lived two days upon tea and molaffes and water, but by the end of two days his mouth and throat were fo completely 11 clofed that he was unable to fwallow any fluid. The poor man had in this time become fo much debilitated, from the want of nouriftiment and the long continuance of his difeafe, that he could not fit up in bed. At this critical moment, when every perfon about him expected he would breath his laft in a few hours, nutritive clyfters were directed to be given, and about half a pint of ftrong beef tea with a few drops of laudanum was injected every four or five hours. In twenty four hours after the firft enema a great alteration was evident, his pulfe rofe, and he appeared to have gained ftrength, being able now to raife himfelf up in bed. By a repetition of the injections, three or four times in the day anc' nearly as often during the night, he was fupported during nine days without receiving into his ftomach a Tingle ounce of folid or fluid nourifhment, a fmall quantityof tea on the ninth day excepted; on the tenth day he fwallowed a quantity fufficient to fupporthimfelf by means of the ftomach. Both the mind and body of this poor patient were improved during thefe nine days, and by proper treatment after the omiffion of theenematahe perfectly recovered his health, In the third volume of the London Medical Obfer- \ vations, page 245, John Silvefter relates a cafe of which the following is a fliort extract. A girl under the effects of mercury got out'of bed when very warm, and took a hearty drink of red wine, this immediately flopped the falivation, and produced an nneafmefs in the ftomach; in a week after a vomiting came on, which in a few days became inceffant, fo that fhe threw up whatever was taken the moment C 12 it reached tHe ftomach. In this fituation fhe conti- nued two months, before application was made to the hofpital; at this late period of her difeafe admittance as a patient was granted her. She was once bled, vomits, cordials, ftonlachics, &c. were all adminillered without the leaft alteration of difeafe. She was now, from debility, fcarcely able to walk or ftand : at this critical moment it was thought advif- able by her phyficians to direct nutritive enemata, and to prohibit her from taking any thing whatever into her ftomach ; an injection of a pint of ftrong mutton broth with the yolk of an egg diffolved in it, was given twice a-day. The effects of thefe clyfters, and abftinence from eating, were, that fhe immediately ceafed to vomit, and in a few days, her fpirits grew better, her ftrength increafed, and her flefh grew firmer. After the injections had been continued for a fortnight, during which time fhe neither eat nor vomited, permiflion was granted her to take a fpoonful of broth, this foon convinced the unfortunate patient that fhe remained in the fame unhappy fituation; the enemata were therefore continued, (I am forry our author does not mention for how long a time) and fome medicines were like- wife adminiftered by way of clyfter, but all without the leaft mitigation of the complaint, for it was at laft removed by reproducing a falivation. During the whole of her difeafe, not excepting the time when the injections were given, fhe had no difcharge downwards from the alimentary canal. In the fecond volume of the Edinburgh Medical r.ffays, page 382, we find a very remarkable cafe *3 recorded by James Eccles, of which I take the- liberty to draw up the following abridgment* A young woman about fixteen had her menftrual difcharge obftructed; this was attended with epi- leptic fits, occurring every month at the time when the menfes ought to have made their appearance. With a view to remove thefe affections, fhe was bled and vomited; foon after the operation of the fecond vomit fhe was feized with a difficulty of fwallowing, which in two or three days increafed fo much in violence, that fhe was unable to fwallow, but on every attempt, fell into a fit, attended with prodigious tremblings and alternate diftentions of the thorax and abdomen, which fometimes continued half an hour, and always ended in a rigidity of the whole body. She continued without eating or drinking from the middle of May to the fifteenth of June, a period of thirty-four days, when fhe again at- tempted to fwallow, but with the fame bad confe- quences. Antifpafmodic and nervous medicines were now applied externally to the neck but without effect. The probang was next reforted to, and was with difficulty forced into the ftomach; but the operation gave temporary relief, for fhe was able without much difficulty to fwallow for three weeks. By the middle of July the fpafm had returned with fo much violence that the poor girl was again unable to fwallow, and fhe continued fifty-four days longer without eating or drinking. During the firft courfe of fafting, and the firft thirty* days of the fecond courfe, fhe was nourifhed by Enemata of broth, fherry wine, and the yolk of eggs. Our author obferves that this unfortunate patient declared flie 14 luflered neither hunger nor thirft during all the time of her fafting, that flie had loft but little of her fiefh, and that her pulfe was full, ftrong, and equal. The fourth cafe that I fhall lay before the reader, is one that my worthy preceptor, Dr. Wiftar, favour- ed mc with; I mail relate it in his own words. " The patient was upwards of fixty years of " age, and very fedentary in her habits. The " difeafe appeared to be fimple dyfpepfia, but was " aggravated inftead of being relieved, by the or- " dinary remedies for that complaint, and finally it " increafed to fuch a degree, that fhe vomited " every thing flie fwallowed, and was affected with " an inceffant naufea; debility increafed in confe- " quence of thefe fymptoms fo much that fhe was " unable to fit up. Enemata with a dram of tindt. " thebaic, in each, were injected to relieve the " naufea, and they produced this effect, but did not " enable the ftomach to retain what was fwallowed. " To cempenfate for the want of aliment in the " ftomach, the enemata were compofed of about " eight ounces of mutton or beef broth added to " the tinct. thebaic, and they were retained a long " time. As the difeafe continued, the enemata, " thus compofed, were injected daily. The bowels ii being extremely inactive, an injection flightly cs ftimulating was previoufiy adminiftered, and ge- c; nerally produced the difcharge of a fmall quantity " of black coloured liquid fceces; an hour after " thefe came away the anodyne nutritive injection *5 " was exhibited, and was generally retained until " the ftimulating injection was ufed next day, which " was about twenty-two hours afterwards. While " the injection was retained fhe lay quiet, and was " not much affected with naufea, unlefs fhe attempt- " ed to eat or drink, but immediately after fwallow- " ing any thing, vomiting came on, and it was " computed by her attendants that fhe always " vomited much more than fhe fwallowed; the " matter difcharged appeared to be the aliment " recently taken, mixed with the gaftric fluids and " mucus. In this ftate, vomiting more than fhe " fwallowed, fhe continued upwards of fix weeks, " when the naufea went off gradually, and her " appetite and power of retaining food returned;. " with this alfo returned her ftrength, which " increafed to a degree greater than ufual, and " continued feveral years, when fimilar complaints " returned, while fhe was in the country, where " the enemata could not be a^miniftered; fhe died " after a lingering illnefs, during which fhe fre- " quently expreffed her wifhes for her former " remedy." I am forry that my experience as a ftudent has not afforded me more facts of a fimilar nature, but I flatter myfelf that the preceding cafes, though few in number, are fufficient to convince any mind of the great power of abforption in the colon, and of the great utility of nutritive enemata in cafes of difeafe in the digeftive organs, or in the organs of deglutition. i6 In every cafe where a fufficient quantity of food cannot be received into the ftomach without the aggravation of difeafe, when the patient is altoge- ther unable to fwallow, or in, cafes where food received into the ftomach is not digefted, or is immediately thrown up ; we ought never to neglect giving our patient the opportunity of recovering by thefe means. Though we cannot always cure the difeafe, yet we may revive and fupport our patient until the remedies proper for the cure of his complaint can be employed with advantage. Of the three patients mentioned that were cured, I will venture to fay there is not one who would not have died before the remedies, employed to cure the different difeafes, could have been effectually adminiftered ; if it had not been for the great affiftance they derived from the nutritive enemata. The laft of the four cafes is doubly interefting, Firft, for the length of time the patient was fupported by the injections ; and, fecondly, for the perfect cure performed by the reft afforded the ftomach. This leads me again to recommend the ufe of nutritive clyfters to the practitioner of medicine, under certain circumftances, and in certain difeafes; particularly in violent dyfpepfia, which {o often baffles the efforts of phyficians. '7 CHAPTER III. Of the Sympathetic Connections of the Great Intestines. JLjLITHERTO I have been confidering the power of abforption ; my intention now is to offer a few obfervations, on another important quality of the animal body, by which medicines act on the whole fyftem although applied locally, I mean fympathy. By this term we underftand the difpofition in one part, to be affected by an application, to another, perhaps remotely fituated from it; for example, an irritation excited in the nofe will throw the diaphragm into violent contractions ; irritation at the neck of the bladder, by a ftone, produces pain at .the glans penis. Upon what principle, or by what means, this wonderful confent of parts exifts, has hitherto been inexplicable, and will remain fo until we are better acquainted with the brain and nervous fyftem. The ftrongeft example of fympathy or nervous connection afforded us, exifts between the ftomach; and the whole iS body ; the connection here is fo ftrong, that a draught of cold water, on a hot fummers day, has deftroyed life in a few minutes, a blow on the pit of the ftomach has induced fyncope and even death. It is by means of this great fympathy that many medicines act on the general fyftem when received into the ftomach, particularly thofe of the narcotic and ftimulating kind. That the large inteftines refemble the ftomach in their fympathetic connection is evident from the fimilarity of effects, produced by the operation of the fame medicines in the ftomach and rectum. It has long been known that bark, injected into the rectum, will cure an intermittent, and the daily ufe of opium, in this way, attended with the fame effects as when taken into the ftomach, goes far to demonftrate the fympathy that exifts between the rectum and. general fyftem. The relation of an experiment made on myfelf, will convince the reader of the powerful effecls of opium when received by enema. At a quarter before i o o'clock, P. M. pulfebeating 52 * ftrokes in a minute, I took an injection of 180 drops of laudanum diluted with two ounces of water; in 15 minutes my pulfe was the fame with regard to frequency, but rather fuller ; in 25 minutes it con- tinued the fame with a flight giddinefs of the head ; in 35 minutes it raifed to $6, but was fmaller and harder ; in 45 minutes, pulfe 56, the affection of the '* My pulfe in health beats 52. *9 head refembled that fcnfation which is felt at the approach of intoxication ; 60 minutes, pulfe 56, the affection of the head continued; 70 minutes, pulfe 72, fmall but tenfe, eyes fomewhat turgid, more languor, and much inclined to a recumbent pofture : in the next ten minutes my pulfe fell from 72 to 60 ftrokes in a minute, langour much increafed. I now refolved to go to bed ; previous to doing this, I dif- charged what I fuppofed to be the whole of the injection without any fceces. At half paft eleven o'clock, A. M. I injected feven drams of wine into the rectum of a fmall dog ; at 12 o'clock, no fenfible effects being produced, nor the firft injection difcharged, I adminiftered feven drams more; in five minutes after the laft injection, he began to move his hind legs v/ith difficulty, and great uncertainty, when attempting to jump he was fure to fall; in a few minutes more he was fcarcely able to walk, falling frequently and running againft every thing that came in his way. In fifteen minutes after the laft injection, he had a large difcharge from the rectum, immediately after which the effects began gradually to difappear. In this manner I intoxicated the fame dog a number of different times. At feveral different times I had fmall quantities of wine injected into my rectum. While under one of thefe experiments, and the only one at which I > examined my pulfe, I found it to be raifed feveral ftrokes in a minute ; but the quantity that 1 could D io retain was too fmall to produce any very obvious effect while my body and mind were in perfect health ; but I am fully convinced that wine may be injected into the rectum with advantage in cafes of great debility. I will here take the liberty of mention- ing, in as few words as poffible,a cafe delivered by Dr. Wiftar in his courfe of Lectures on Anatomy, which in a remarkable manner points out the fimilarity of effects produced in the ftomach and rectum by fpiritous liquors. The fubject of this cafe was a man much addicted to the ufe of .ftrong drink, and pro- bably from this caufe was tempted to cut his throat, which he one day effected ; while he laboured under the wound, it was with great difficulty that any thing could be fwallowed. His phyfician, the late Dr. Way of this city, whofe death is ever to be lamented, directed nutritive enemata, and thefe anfwered the purpofe of aliment; but the poor patient foon found that he fuffered materially from the want of the diffufible ftimulus, and one day, when his wife was about giving him an injection, he defired her to add fome ardent fpirits to the nutritive matter ; the effect foon convinced him that he derived every benefit from the fpirit in this way, that he was accuftomed to do when he drank it; and after this difcovery, he did not let a fingle day pafs without taking feveral dofes. Thefe experiments, in conjunction with daily expe- rience, can leave no doubt of the great advantages to be derived on certain occafions from the admini- ftration of medicines, particularly thofe of a narcotic ftimulating quality, by enemata. 21 I cannot fay from experiment, but I think analogy warrants me in (o doing, that avery medicine, the effects of which are communicated to the general fyftem by the fympathetic connection of the ftomach, will have a fimilar effect when thrown up the rectum provided the dofe is proportionably large. The relative dofe for the rectum, has by fome been computed to be two thirds larger than that for the ftomach, but from experiment I am led to believe that it does not require fo much. On "comparing the effects of fixty drops of tinct. thebaic, in the ftomach, with thofe produced by one hundred and eighty drops in the rectum, I found that the effects of the latter were fomething ftronger than thofe of the former. This I think juftifies me in concluding, that the relative dofe for the rectum does not require to be two thirds larger, but that little more than a double dofe will anfwer the fame intentions in the inteftines. Having thus fatisfied myfelf of the fympathetic connection- between the rectum and general fyftem; I was induced to try whether any particular fympathy exifted between the ftomach and large inteftines: the mode that ftruck me as beft calculated to afcertain this point, was the injection of emetic medicines; I made a number of experiments with tart, emetic, and feveral with ipecac, a few of which I fhall now proceed to relate. After having ufed as much as eight grains of the emetic tart, by enema, without the leaft affection of 22 the ftomach, I was induced to think that a ftill larger quantity might produce fome effect, and I ventured on taking thirteen grains; this was injected at half paft eleven o'clock, A. M. diffolved in two ounces of water, immediately after I had perfectly evacuated my rectum. This on being firft thrown up produced fome irritation, but it did not continue longer than five minutes. Not the flighteft affection of the ftomach was obfervable, from the time it was injected, until it was difcharged, which was at ten o'clock, P. M. of the fame day. In the act of evacuating, I had fome tenefmus, and a little forenefs at the verge of the anus, but of this I felt nothing ten minutes after. So inadtivewas the tart, emetic upon this part, that it did not even excite a difcharge of fceces, nor produce the leaft effect on the general fyftem that was obfervable. From the great irritation produced in the rectum by injections of ipecac. I did not venture to increafe the dofe beyond half a dram; this quantity was adminiftered one afternoon at half paft four o'clock, mixed with two ounces of warm water, and was not difcharged until nine o'clock, A. M. the next day. In the intermediate time, no effects of any kind were obfervable either on the ftomach or general fyftem, but at four in the afternoon I had another very fmall difcharge, which was attended with confiderable {training, and from this time I had almoft a conti- nued defire to evacuate from the rectum ; in two or three hours went to ftool three or four times, and thefe difcharges, though very fmall, were all attended with tenefmus; between thefe evacuations I was not free from uneafinefs, but felt a confiderable throbbing about the verge of the anus, fimilar to that experienced in a phlegmon. Would not an injection of this kind ferve to bring on the hsemor- rhoidal flux ? From.the two laft mentioned experiments, and feveral others of a fimilar nature not related; I conclude that there is no fpecific connection between the ftomach and rectum, and that little can be expected from enemata in exciting the action of the ftomach, without it is in confequence of their effect upon the general fyftem. H CHAPTER IV. On the Application of Medicines to the External Surface. X H E utility to be derived from the applk cation of medicines to different parts of the body, muft forcibly' ftrike every mind, upon confidering how often we are prevented from applying them with effect through the medium of the alimentary canal by its many difeafes ; and the great difpofition there is in the different parts of the animal body to become habituated to the action of medicines applied imme- diately to them. It is a fact well known, that when one part has become accuftomed to the action of a medicine, we may apply it to another with every advantage ; for inftance, when the ftomach, from a long continued ufe, has become as it were paralytic to the powers of opium, the rectum will receive its impreffions as forcibly as though it never had been applied to any part of the body. This fact is further corroborated by a very fimple experiment. Any perfon in the habit of ufing tobacco, and who has always been accuftomed to hold the chew on one 25 fide only, will by removing it to the oppofite fide of the mouth, experience the fame difagreeable effects that he did on his firft commencing the ufe of this plant. In the preceding pages I have confideredthe rectum as an advantageous part for the application of nou- riftiment and medicine, when the ftomach, mouth, or cefophagus are difeafed. In cafes where we wifh further to affift the operation of medicines in the ftomach and rectum, or where both thefe organs are difeafed ; a good opportunity is afforded us by the external furface of the body. Medicines applied to the fkin act on the two prin- ciples fpoken of, namely, abforption and nervous fympathy. That the firft of thefe powers is feated in the fkin, is evident, by effential oils having been tafted in the mouth, a fhort time after they were rubbed on fome part of the fkin ; by the external ufe of terebinthinates, by the daily introduction of mercury into the fyftem in this way, and by the abforption of many poifons from the external furface; the bark, bath, and jacket have alfo been found of fervice in intermittents, and thefe probably act as much through the medium of the nerves as of the abforbents. In the memoirs of the medical fociety of London, we find a letter from Mr. Sherwen to Dr. Lettfom on the external abforption of tartar emetic. In this communication the author obferves, naufea, great perfpiration, gentle purging, an increafed flow of 26 urine, and in one cafe an eruption with an itching of the fkin, as the effects of from five to ten grains (which is the largeft dofe he there mentions having ufed) of tart. emet. when abforbed by rubbing it on the hands, and in one inftance, on the fide and region of the ftomach. It might be thought prefumption in me to con- tradict fo refpectable an author as Mr. Sherwen; this I will avoid doing, but fhall relate fome expe- riments fimilar to Mr. Sherwen's, with their refults, and leave the unprejudiced reader to judge for himfelf. At feveral different times, I rubbed 12 grains of tart. emet. moiftened with a fmall quantity of water into the palms of my hands ; this was done in the evening a fliort time before going to bed. I flept found as ufual all night, without experiencing the leaft naufea, perfpiration, or purgative effects, either during the night or next day, but rofe and eat my breakfaft with my accuftomed good appetite. At my defire, a fellow-graduate repeated the experi- ment juft related, without experiencing any fenfible effects from the medicine. The following experiment was made by a fellow ftudent. At 8 o'clock, P. M. he rubbed 12 grains of tart. emet. with the addition of two drams of water, into the palms of his hands ; in half an hour after, the firft 12 grains having produced no effects, 12 grains more were adminiftered in the fame man- ner. No effects were obfervable in three hours 27 after, when he retired to bed. About fix o'clock next morning a moifture of the fkin was obfervable ; this the gentleman was inclined to attribute more to his having flept under an unufual quantity of bed clothes, than to the medicine. No naufea, purging, or eruption followed. Two fcruples of tart. emet. made into a pafte with a little water, and kept applied to the pit of the ftomach for 12 hours, produced no difcoverable operation. Peter V-----, afflicted with chronic rheumatifm, rubbed a table fpoonful of a faturated folution of tart. emet. in water into his knee and thigh ; this he continued to do every night, for a week, without its once naufeating, or fweating him. He thought the medicine purged him flightly the fecond morning after he commenced the ufe of it; this effect was not obferved at any other time during the whole courfe. The complaint of this patient was not relieved by this remedy. Catharine G----- was troubled with rheumatifm and a fwelling of her ftomach ; I ordered her to rub a table fpoonful of a faturated folution of tart. emet. in water on her thigh and flomach ; this was done the firft night; the next day ouefted her to ufe two table fpoonfuls, tr.-!s ne iim * entinued to ufe every evening, for f . ■ r fix times. ho woman was feveral times nm