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JVo. PRESENTED BY—

ARMY MEDICAL LIBRARY

EXPERIMENTS

OBSSRVATXO^S

GASTRIC JUICE

PHYSIOLOGY OF DIGESTION:

BY WILLIAM BEAUMONT, M. D.

Surgeon in the U. S. Army.

PLATTSBURGH,

FRINTED BY F. P. ALLEN.

1833.

Entered according to Act of Congress^ in the year 1 833, by William Beaumont, M. Z). in the Office of the District Clerk of the United Stales for the Southern District of JSew-York.

TO JOSEPH LOVELL, M. D.

SURGEON GENERAL OF THE UNITED STATES' ARMY,

Whose merit justly entitles him to the rank which he holds, And whose zeal in the cause of Medical Science is equalled only by his ability to promote it. As a tribute of respect for his public and pri- vate virtues. And as a feeble acknowledgement for a long tried and unvarying friendship, This work is respectfully dedicated, by THE AUTHOR.

PREFACE.

THE present age is prolific of works on physiol- pgy; therefore in offering to the pubUc anothe^ book relative to an important branch of this science, it will perhaps be necessary to assign my motives.

They are, first, a wish to comply with the repeated and urgent solicitations of many medical men who have become partially acquainted with the facts and observations it is my intention to detail ; men, in whose judgment I place confidence, and who have expressed their conviction of the deep importance of the experiments, the result of which I mean herewith to submit to the public : secondly, (and it is that which mainly influences me,) my own firm conviction that medical science will be forwarded by the pub- lication.

I am fully aware of the importance of the subject which these experiments are intended to illustrate, as well in a pathological as in a physiological point of view; and I am therefore willing to risk the cen- sure or neglect of critics, if I may be permitted to cast my mite into the treasury of knowledge, and to be the means, either directly or indirectly, of subserv- ing the cause of truth, and ameliorating the condi- tion of suffering humanity.

I make no claim to originality in my opinions, as it respects the existence and operation of the gastric juice. My experiments confirm the doctrines (with some modifications) taught by Spall.vnzini, and ma-

ny of the most enliglitencd physiological writers. They are experiments made in the true spirit of en- quiry, suggested by the very extraordinary case which gave me an opportunity of making them. I had no particular hypothesis to support ; and I have there- fore honestly recorded the result of each experiment exactly as it occurred.

The reader will perceive some slight seeming dis- crepancies, which he may find it difficult to reconcile ; but he will recollect that the human machine is en- dowed with a vitality which modifies its movements in diflerent states of the system, and probably pro- duces some diversity of eflects from the same causes.

I had opportunities for the examination of the in- terior of the stomach, and its secretions, which has never before been so fully oflTered to any one. This most important organ, its secretions and its opera- tions, have been submitted to my observation in a ve- xy extraordinary man)ier, in a state of perfect health, and for years in succession. I have availed myself of the opportunity afibrdcd by a concurrence of circum- stances which probably can never again occur, with a zeal and perseverance proceeding from motives which my conscience approves ; and I now submit the result of my experiments to an enlightened public, who I doubt not will duly appreciate the truths disco- vered, and the confirmation of opinions which before rested on conjecture.

I submit a body of facts which cannot be invahdn ted. My opinions may be doubted, denied, or ap- proved, according as they conflict or agree with the opinions of each individual who may read them ; bu(

their worth will be best determined by the foundation on which they rest — the incontrovertible facts.

I avail myself of this opportunity to make my grate- ful acknowledgements to Doctor Joseph Lovell, Sur- geon General of the United States' Army, (to whom 1 am under obligations for personal kindness and offi- cial exertions in affording facilities for prosecuting the experiments;) — to Professors SILLIMA^, Knight, Ives and Hubbard, of Yale.CoUege, Dunglison, of the Virginia University, and Sewall, Jones, Henderson and Hall, of Columbian College, for their unsolici- ted friendship; for the interest which they have taken in the experiments, and for the generous encourage- ment which they have given to the proposed publica- tion. To Doctor Samuel Beaumont, of Plattsburgh, N. Y. I am particularly indebted for the assistance which he has rendered me in arranging and prepa- ring my notes for the press.

INTRODUCTION.

THE experiments which follow were commenced in 1825, and have been continued, with various in. terruptions, to the present time, (1833.) The op- portunity for making them was aflbrdcd to me in the fallowing way.

Whilst stationed at Michillimackinac, Michigan Territory, in 1822, in the military service of the Uni- ted States, the following case of surgery came un- der my care and treatment.

Alexis St. Martin, who is the subject of these experiments, was a Canadian, of French descent, at the above mentioned time about eighteen years of age, of good constitution, robust and healthy. He had been engaged in the service of the American Fur Company, as a voyageur, and was accidentally wounded by the discharge of a musket, on the 6th of June, 1822.

The charge, consisting of powder and duck shot, was received in t!ic left side of the youth, he being at a distance of not more than one yard from the muzzle of the gun. The contents entered posteri- orly, and in an oblique direction, forward and in- ward, hterally blowing off integuments and muscles of the size of a man's hand, fracturing and carrying away the anterior half of the sixth rib, fracturing the fifth, lacerating the lower portion of the left lobe of the lungs, the diaphragm, and perforating the sto- mach,

B

Id

INTRODUCTION.

The whole mass of materials forced from the muS' ket, together with fragments of clothing and pieces of fractured ribs, were driven into the muscles and cavity of the chest.

I saw him in twenty-five or thirty minutes after the accident occurred, and, on examination, found a portion of the lung, as large as a Turkey's egg, pro- truding through the external wound, lacerated and burnt ; and immediately below this, another protru- sion, which, on further examination, proved to be a portion of the stomach, lacerated through all its coats, and pouring out the food he had taken for his breakfast, through an orifice large enough to admit the fore finger.

In attempting to return the protruded portion of the lung, I was prevented by a sharp point of the fractured rib, over which it had caught by its mem- branes ; but by raising it with my finger, and clipping off the'point of the rib, I was able to return it into its proper cavity, though it could not be retained there, on account of the incessant efforts to cough.

The projecting portion of the stomach was nearly as large as that of the lung. It passed through the lacerated diaphragm and external wound, mingling the food with the bloody mucus blown from the lungs.

After cleansing the wovmd from the charge and other extraneous matter, and replacing the stomach and lungs as far as practicable, I applied the carbo- nated fermenting poultice, and kept the surrounding parts constantly wet with a lotion of muriate of am- monia and vinegar ; and gave internally the aq. acet. am. with camphor, in libej^l quantities.

WTRODUCTION, 11

Under this treatment a strong reaction took place in about twenty-four hours, accompanied with high arterial excitement, fever, and marked symptoms of inflammation of the lining membranes of the chest and abdomen, great difficulty of breathing, and dis- tressing cough.

He was bled to the amount of eighteen or twenty ounces, and took a cathartic. The bleeding reduced the arterial action, and gave relief. The cathartic had no effect, as it escaped from the stomach through the wound.

On the 5th day a partial sloughing of the integu- ments and muscles took place. Some of the pro- truded portions of the hmg, and lacerated parts of the stomach, also sloughed, and left a perforation into the stomach, plainly to be seen, large enough to admit the whole length of my fore-finger into its cavity ; and also'a passage into the chest, half as large as my fist, exposing to view a part of the lung, and permitting the free escape of air and bloody mucus at every respiration,

A violent fever continued for ten days, running in- to a typhoid type, and the wound became very fojtid. On the eleventh day, a more extensive sloughing took place, the febrile symptoms subsided, and the whole surface of the wound assumed a healthy and granulating appearance.

For seventeen days, all that entered his stomach by the oesophagus, soon passed out through the wound ; and the only way of sustaining him was by means of nutricious injections per anus, until com- presses and adhesive straps could be applied so as to

)2 IN'TRODUCTION.

retain his food. During this period no alvinc evacu- ations could be obtained, although cathartic injec- tions were given, and various other means were a- dopted to promote them.

In a few days after firm dressings were applied, and the contents of the stomach retained, the bowels became, gradually excited, and, with the aid of ca- thartic injections, a very hard, black, foetid stool was procured, followed by several similar ones ; alter which the bowels became quite regular, and contm- ued so.

The cataplasms were continued until the slough- ing was completed, and the granulating process fully established; and were afterwards occasionally resort- ed to, when the wound became ill conditioned. The aq. acet. am. with camphor was also continued for several weeks, in proportion to the febrile symptoms, and the foetid condition of the wound.

No sickness, nor unusual irritation of the stomach, not even the slightest nausea, was manifest during the Avhole time ; and after the fourth week, the appe- tite became good, digestion regular, the alvine evac- uations natural, and all the functions of the system perfect and healthy.

By the adhesion of the sides of the protruded por- tions of the stomach to the pleura costalis and the external wound, a free exit was afforded to the con- tents of that organ, and effusion into the abdominal cavity was thereby prevented.

Cicatrization and contraction of tlie external wound commenced on the fifth week; the stomach became ,'norc iirnily attached to the pleura and intercostal?,

INTRODUCTION. 13

by its external coats ; but showed not the least dis- position to close its orifice ; this (the orifice) termi- nated as if by a natural boundary, and left the perfo- ration, resembling, in all but a sphincter, the natural anus, with a slight prolapsus.

Whenever the wound was dressed the contents of the stomach would flow out, in proportion to the quantity recently taken. If the stomach happened to be empty, or nearly so, a partial inversion Avould take place, unless prevented by the application of the finger. Frequently in consequence of the derange- ment of the dressing, the inverted part would be found of the size of a hen's egg. No difficulty, how- ever, was experienced in reducing it by gentle pres- sure with the finger, or a sponge wet Avith cold water, neither of which produced the least pain.

In the seventh week, exfoliation of the ribs, and a separation of their cartilaginous ends, began to take place.

The sixth rib was denuded of its periosteum for about two inches from the fractured part, so that I was obliged to amputate it about three or four inches from its articulation with the rib. This I accomplish- ed by dissecting back the muscles, securing the inter- costal artery, and sawing ofl' the bone with a very fine narrow saw, made for the purpose, introduced be- tween the ribs, without injury to the neighbouring parts. Healthy granulations soon appeared, and formed soundly over the amputated end. About half the inferior edge of the fifth rib exfoliated, and sepa- rated from its cartilage.

After the removal of these pieces of bone, I at^

14 INTRODUCTION.

tempted to contract the wound, and close the perfo- ration of the stomach, by gradually drawing the edges together with adhesive straps, laid on in a radiated form.

The circumference of the external wound was at least twelve inches, and the orifice in the stomach nearly in the centre, two inches below the left nipple, on a line drawn from this to the point of the left ilium.

To retain his food and drinks I kept a compress and tent of lint, fitted to the shape and size of the perforation, and confined there by adhesive straps.

After trying all the means in my power for eight or ten months to close the orifice, by exciting adhesive inflammation in the lips of the wound, without the least appearance of success, I gave it up as impracticable in any other way than that of incising and bringing them together by sutures ; an operation to which the patient would not submit.

By the sloughing of the injured portion of the lung, a cavity was left as large as a common sized teacup, from which continued a copious discharge of pus for three months, when it became filled with healthy granulations, firmly adhering to the pleura, and soundly cicatrized over that part of the wound.

Four months after the injury was received, an ab- scess formed about two inches below the wound, nearly over the cartilaginous ends of the first and second false ribs, very painful, and extremely sore, producing violent symptomatic fever. On the application of an emoUient poultice it pointed ex- ternally. It was then laid open to the extent of three inchef, and several shot and pieces of wad

I

INTRODUCTIO?f. 15

extracted. After which a gum-elastic bougie could be introduced three or four inches in the longitudinal direction of the ribs, towards the spine. Great pain and soreness extended from the opening of the ab- scess^ along the track of the cartilaginous ends of the fale ribs, to the spine, with a copious discharge from the sinus.

In five or six days there came away a cartilage, one inch in length. In six or seven days more, another, an inch and a half long ; and in about the same length of time, a third, two inches long, were dis- charged. And they continued to come away every five or six days, until fiue were discharged from the same opening, the last three inches in length. They were all entire, and evidently separated from the false ribs.

The discharge, pain and irritation, during the four or five weeks these cartilages were working out, greatly reduced the strength of the patient, produced a general febrile habit, and stopped the healing pro- cess of the original wound.

Directly after the discharge of the last cartilage, inflammation commenced over the lower end of the sternum, which by the usual applications, terminated in a few days in a large abscess, and from which, by laying it open two inches, I extracted another carti- lage, three inches in length. The inflammation then abated ; and in a day or two another piece came a- way, and the discharge subsided.

To support the patient under all these debilitating circumstances, I administered wine, with diluted mu- riatic acid, and thirty or forty drops of the ticture of

16

INTRODUCTION'.

assafojtjda, three times a day : which appeared to produce the desired effect, and very much improved the condition of the wound.

On the third of January, 182:5, 1 extracted another cartilage from the opening over the sternum, an inch and a half long ; and on the fourth another, two inch- es and a half in length, an inch broad at one end, and narrowing to less than half an inch at the other. This must have been the ensiform cartilage of the sternum. After this the sinus closed, and there was no return of inflammation.

From the month of April, 1823, at which time he had so far recovered as to be able to walk about and do light work, enjoying his usual good appetite and digestion, he continued with me, rapidly regaining his health and strength.

By the 6th of June, 1823, one year from the time of the accident, the injured parts were all sound, and firmly cicatrized, with the exception of the aperture in the stomach and side. This continued much in the same situation as it was six weeks after the wound was received. The perforation was about two and a half inches in circumference, and the food and drinks constantly exuded, unless prevented by a tent, compress and bandage.

From this time he continued gradually to improve in health and strength, and the newly formed integu- ments over the wound became firmer and firmer. At the point where the lacerated edges of the muscular coat of the stomach and intercostal muscles met and united with the cutis vera, the aiiicle of the external surface and the mucous membrane of the stomach ap-

INTRODUCTION. 17

proached each other very nearly. They did not unite, Hke those of the hps, nose, &:c., but left an interme- diate marginal space, of appreciable breadth, com- pletely surrounding the aperture. This space is a- bout a line wide ; and the cutis and nervous papillae are unprotected, as sensible and irritable as a blistered surface abraded of the cuticle. This condition of the aperture still continues, and constitutes the principal and almost only cause of pain or distress experienced from the continuance of the aperture, the introduc- tion of instruments, &c. in the experiments, or the exudation of fluids from the gastric cavity.

Frequent dressings with soft compresses and ban- dages were necessarily applied, to relieve his suffer- ing and retain his food and drinks, until the winter of 1823-4. At this time, a small fold or doubling of the coats of the stomach appeared, forming at the supe- rior margin of the orifice, slightly protruding, and in- creasing till it filled the aperture, so as to supersede the necessity for the compress and bandage for re- taining the contents of the stomach. This valvular formation adapted itself to the accidental orifice, so as completely to prevent the efflux of the gastric con- tents when the stomach was full, but was easily de- pressed with the finger.

In the spring of 1824 he had perfectly recovered his natural health and strength ; the aperture remain- ed ; and the surrounding wound was firmly cicatrized to its edges.

In the month of May, 182.'}. I commenced my first series of gastric experiments with him, at Fort Mackinac, Michigan Territory. In the month of C

18 INTRODUCTION.

June following, I was ordered to Fort Niagara, N. Y. where, taking the man with me, I continued my ex- periments until August. Part of these experiments were published in 1826, in the 29th number of the Philadelphia '• Medical Recorder," conducted by Doctor Samuel Calhoun. About this time, (August 1825) I took St Martin with mc to Burlington, Ver- mont, and from thence to Plattsburgh, New-York. From the latter place, he returned to Canada, his na- tive place, without obtaining my consent.

Being unable to ascertain the place of his resort, I gave him up as a lost subject for physiological ex- periments, and returned to my post at the west again. I did not, however, remit my efforts to obtain infor- mation of his place of residence and condition.

He remained in Canada four years, during which period he married, and became the father of two children ; worked hard to support his family ; and enjoyed robust health and strength. In 1825, as he has informed me, he engaged with the Hudson Bay Fur Company, as a voyageur to the Indian country. He went out in 1827, and returned in 1828 ; and sub- sequently laboured hard to support liis family un- til 1829.

Accidentally learning about this time where he was, and that he enjoyed pcricct health, I made ar- rangements with the agents of the American Fur Company .who annually visit Canada for the purpose of procuring voyageurs, to find and engage him for my f^ervice. if practicable. After considerable difficulty, and at great expense to me, they succeeded in enga- ging him, and transported him from Lower Canada,

INTRODtTCTION. 19-

with his wife and two children, to me, at Fort Craw- ford, Prairie du Chien, Upper Mississippi, a distance of nearly two thousand miles, in August, 1829. His stomach and side were in a similar condition as when he left me in 1825. The aperture was open, and his health good.

He now entered my service, and I commenced an- other series of experiments on the stomach and gastric fluids, and continued them, interruptedly, until March, 1831. During this time, in the in- tervals of experimenting, he performed all the duties of a common servant, chopping wood, carrying bur- thens, &c. with little or no suffering or inconvenience from his wound. He laboured constantly, became the father of more children, and enjoyed as good health and as much vigour as men in general. He subsisted on crude food, in abundant quantities, ex- cept when on prescribed diet, for particular experi- mental purposes, and under special observance.

In the spring of 1831 circumstances made it expe- dient for him to return with his family from Prairie du Chien to Lower Canada again. I relinquished his en- gagements to me for the time, on a promise that he would return when required, and gave him an outfit for himself, wife and children. They started in an open canoe, via the Mississippi, passing by St Louis, Mo.; ascended the Ohio river; then crossed the state of Ohio, to the Lakes ; and descended the Erie, On- tario, and the River St. Lawrence, to Montreal, where they arrived in June. He remained in Canada with his family until October, 1 832. in good health, and at hard labour. He nTia in the midst of the cliohra epi-

20 INTRODUCTION.

demic, at the time it prevailed, and passed through Canada, and withstood its ravages with impunity, while hundreds around him fell sacrifices to its fatal influence.

In November, 1832, he again engaged himself to me for twelve months, for the express purpose of submitting to another series of experiments. He joined me at Plattsburgh, N. Y., and travelled with me to the city of Washington, where, with the facili- ties aflbrded by the head of the Medical Depart- ment, the experiments were continued upon him from November, 1832, to March, 1833.

During the whole of these periods, from the spring of 1824 to the present time, he has enjoyed o-cwera/ good health, and perhaps suflfered much less predis- position to diseapc than is common to men of his age and circumstances in life. He has been active, athletic and vigorous ; exercising, eating and drink- ing like other healthy and active people. For the last four months, he has been unusually plethoric and robust, though constantly subjected to a continued series of experiments on the interior of the stomach ; allowing to be introduced or taken out at the aper- ture di^erent kinds of food, drinks, elastic catheters? thermometer tubes, gastric juice, chyme, &c., almost daily, and sometimes hourly,

Such have been this man's condition and circum- stances for several years past ; and he now enjoys the most perfect health and constitutional sound- ness, with every function of the system in full force and vigour.

UTTRODUCTION. 21

Mode of extracting the Gastric Juice. — The usual method of extracting the gastric juice, for experi- ment, is by placing the subject on his right side, de. pressing the valve within the aperture, introducing a gum-elastic tube, of the size of a large quill, five or six inches into the stomach, and then turning him on the left side, until the orifice becomes dependent. In health, and when free from food, the stomach is usu- ually entirely empty, and contracted upon itself. On introducing the tube, the fluid soon begins to flow, first by drops, then in an interrupted, and sometimes in a short continuous stream. Moving the tube about, up and down, or backwards and forwards, increases the discharge. The quantity of fluid ordinarily obtained is from four drachms to one and a half or two ounces, varying with the circumstances and condition of the stomach. Its extraction is generally attended by that peculiar sensation at the pit of the stomach termed sinking, with some degree of faintness, which renders it necessary to stop the operation. The usual time of extracting the juice is early in the morn- ing, before he has eaten, when the stomach is empty and clean.

On laying him horizontally on his back, pressing the hand upon the hepatic region, agitating a little, and at the same time turning him to the left side, bright yellow bile appears to flow freely through the pylorus, and passes out through the tube. Some- times it is found mixed with the gastric juice, without this 'operation. This is, however, seldom the case, unless it has been excited bv some other cause.

22 INTRODUCTION.

The chymous fluids are easily taken out by de- pressing the valve within the aperture, laying the hand over the lower part of the stomach, shaking a little, and pressing upwards. In this manner, any quantity necessary for examination and experiment can be obtained.

Valve — The valve mentioned above, is formed by a slightly inverted portion of the inner coats of the sto- mach, fitted exactly to fill the aperture. Its principal and most external attachment is at the upper and pos- terior edge of the opening. Its free portion hangs pen- dulous, and fills the aperture when the stomach is full, and plays up and down, simultaneously with the respi- ratory muscles, when empty.

On pressing down the valve when the stomach is full, the contents flow out copiously. When the stom. ach is nearly empty, and quiescent, the interior of the cavity may be examined to the depth of five or six inches, if kept distended by artificial means ; and the food and drinks may be seen entering it, if swaUowed at this time, through the ring of the aesophagus. The perforation through the walls of the stomach, is about three inches to the left of the cardia, near the left su- perior termination of the great curvature. When entirely empty, the stomach contracts upon itself? and sometimes forces the valve throuyh the orifice together with an additional portion of the mucous membrane, which becomes completely inverted, and forms a tumour as large as a hen's egg. After lying OH the left side, and sleeping a few hours, a still larg- er portion protrudes, and spreads out over the exter-t

INTRODUCTIOIT. 23

faal integuments, five or six inches in cireumference, fairly exhibiting the natural rugas, villous membrane, and mucous coat, lining the gastric cavity. This ap- pearance is almost invariably exhibited in the morn- ing, before rising from his bed. Plattsburgh, 1833.

nTTRODUCTION.

25

This engraving represents the ordinary appearance of the left breast and side, the aperture filled with the valve ; the subject in an erect position.

AAA The circumference and edge of the aper- ture, within which is seen the valve.

B The attachment of the valvular portion of the stomach to the superior part of the aperture.

C The nipple.

1) The anterior portion of the breast.

E The scar where the opening was made with the scalpel, and the cartilages taken out.

F F F F Cicatrice of t'ri'.^ original wound, around the aperture. D

IKTRODUCTIOK.

27

l','i''ili

This engraving represents the appearance of th« aperture with the valve depressed.

AAA Edges of the aperture through the integ- uments and intercostals, on the inside and around which is the union of the lacerated edges of the per- forated coats of the stomach witii the intercostals and skin.

B The cavity of the stoinacli, n'hcn the vah (< is depressed.

C Valve, depressed witliin the cavity of tho 3I0- mach-

E E E E Cicatriceof the original wound.

F The nipple.

INTRODUCTION.

39

This engraving represents a portion of the sto- mach prolapsed through the aperture, with the inner surface inverted, and spread out over the integuments of the side.

A A A A A Folds or rugae of the inner coats of the stomach.

B B B B Interstices, filled with raucous substance*

C The nipple.

PRELIMINARY OBSERVATIONS.

I do not design, in the following remarks, to present any thing like a systematic treatise on digestion. Works of this kind, treating of the subject both phys- iologically and pathologically, have so multiphed of late, as to render an attempt on my part, entirely a work of supererogation, even if I believed myself qualified for the task. I consider myself but a hum- ble inquirer after truth — a simple experimenter. And if I have been led to conclusions opposite to the o- pinions of many who have been considered the great luminaries of physiology, and, in some instances, from all the professors of this science, I hope the claim of sincerity will be conceded to me, when I say that such difference of opinion has been forced upon me by the convictions of experiment, and the fair de- ductions of reasoning.

I shall not attempt an anatomical description of the organs of digestion, for the reasons given above. In a work professedly elementary, such descriptions are essential. The medical profession arc acquaint- ed with these organisms. The general reader, if he have a wish for information of this kind, is referred to anatomical authors generally, or to the physiologi- cal writings of Richerand, Broussais, Magendie, Bos- tock, Fordyce, Paris, Jackson and Dunglison, the

32 PRF.T.IMINART

last of which, as containing the sum of what has been taught in tiio schools on the subject of physi- ology generally, arranged in a clear and distinct manner, and Avith the assistance of numerous plates, is well worthy his perusal.

With a view to comment on my experiments, and to elucidate my opinions on the subject of digestion, I shall divide my observations into the following heads :

Section 1st. Of Miment. Section 2d. Of Hunger and Thirst. Section 3d. Of Salisfadion and Satiety. Section 4th. Of Mcs'ication, Insalivation and Deglu- tition. Section 5th. Of Digestion by the Gastric Juice. Section Gth. Of the appearance of the Villous Coat, and of the Motions of ih". Stomach. Section 7th. Of Cliy- lificaticn, an:! [^scs of the Bile and Pancreatic Juice

SECTION I

Of Aliment.

Man is said to be an omnivoTous animal^ destined to procure his food from both the animal and veget- able kingdoms. The inhabitant of temperate cli- mates is unquestionably so. It would be interesting to ascertain by experiment whether he could be sus- tained by habit, from infancy, on the productions of either of these grand divisions. If the result should be favourable to the demonstration of this proposi- tion, though it might still more unsettle the opinJ(jns of physiologists, it would be aii evidence of this truth, that man is a creature of habit and circum- stance, carrying about him the effects of primeval disobedience, destined not only to earn his food by his own exertions, but to partake of such as the cli- mate in which he resides may supply to him. Ap- proximating to this are the habits of people of differ- ent quarters of the world — those of Asia, who live almost exclusively on vegetable and farinaceous food, and those of the northern regions of America, who derive their food principally from fish, oil and flesh.

34

PRELIMINARY

Other substances have sometimes been used a^ aliment ; and Professor Dunglison mentions, on the authority of Humboldt, that the Ottomaques, a tribe of Indians of South America, are in the habit of using " an unctions earth, or a species of pipe clay," as an article of diet. Whether nutriment can be supplied by such articles alone, is extremely problematical. In all countries, some persons are found who are in the constant habit of eating large quantities of clay, chalk, slate stone, &;c. Such practices may be re- garded as evidence, if not of a diseased, at least of a vitiated appetite ; though it often happens that alka- line and absorbent substances arc used medicinally with advantage, particularly where much acidity of the stomach prevails.

As it respects the inhabitants of Europe and their American descendants, as well as most other natives of temperate climates, it is well known that they de- rive their nourishment from both the animal and ve- getable kingdoms.

The facility of digestion of different articles ofdiet, and the quantity of nutrient principles which they contain, have heen subjects of some discrepance of opinion among physiologists. They have, however, settled down into a belief, probably as near the truth as practicable, that animal food is more readily as- similated, and affords more nutrition in a o-iven quantity, than vegetable or farinaceous food.

Animal food has been divided into fibrino, "-olatine and albumen, and a comparison drawn between their degrees of digestibility. But it will occur to cvcrv one at all acquainted with the subject, that almo.-^t

OBSERVATIONS. 35

.every portion of animal food contains an admixture of all these principles, and it is consequent! very difficult to come to a correct conclusion. The truth is, there can be no general rule on this subject. The faciUty of digestion is modified by so many cir- cumstances, as health, disease, idiosyncracy, habit, and preparation of food, that a rule which would ap- ply in one case would be incorrect in another. It de- pends more upon other distinctions than upon those relating to the chemical composition of the food. Albumen, (one of these chemical divisions,) if taken into the stomach, either very slightly or not at all co- agulated, is perhaps as rapidly chymified as any artir cle of diet we possess. If perfectly formed into hard coagulae, by heat or otherwise, and swallowed in large soHd pieces, it experiences- a very protracted digestion. The reason is obvious. In the first case the albumen becomes finely coagulated, and divided in ihe stomach ; in the second, it is less susceptible of subdivision *rom its hardness. Fibrine and gelatine are affec'^ed in the same way. If tender and finely divided, they are disposed of readiiy ; if in large and solid masses, digestion is pioportionably retarded. Minuteness of didsion and tenderness of fibre are the two grand essentials for opeeciy c'nd er.3y digestion. By referring to .iiy <5,'ip3r/7-.6?r:.:, it ".vill ^c seen that those articles of diet which were ai'lrri't'ed to the action of the gastric juice, either arhGd.-.-ty, -,vhen out of the stomach, or in the stomach, by natural processi were dissolved in proportion to the fineness of their division or their solidity — the one rapidly, and the other slowly.

36 PRELIMINARY

The digestion of animal and vegetable diet re- quires the same process, tliough one may afford a larger proportion of the nutrient principle than the other. Generally speaking, vegetable aliment re- quires more time, and probably greater powers of the gastric organs, than animal. Its digestibility is, however, dependant upon the same laws as those that govern the solution of animal food ; and it is fa- cilitated by division and tenderness.

The ultimate principles of nutriment are probably always the same, whether obtained from animal or vegetable diet. It Avas said by Hippocrates, that " there are many kinds of aliments, but that there is at the same time but one aliment." This opinion hag been contested by most modern physiologists ; but I see no reason for scepticism on this subject. Some imperfect experiments which I instituted on the ope- rations of the hepatic and pancreatic juices, and which will be found in a subsequent part of this volume, tend to throw some light on the subject. Chyme was submitted to the action of these fluids, and they invariably produced similar effects. A fluid was se- parated, varying slightly in colour, but of the same apparent consistence and identity ; and was increas- ed or lessened in proportion to the quality of the food of wliich the chyme was formed. Whether this fluid was or was not imperfectly formed chyle, is a matter of opinion only. The circulating fluids of the sys- tem are always nearly the same, in health, and that which goes to supply and replenish them, should con- F'l^quently possess the same invariable properties. Chylr- "u'cr its separntion in the intestines, is proba-.

OBSERVATIONS. 37

Uy further changed and perfected by the action of the lacteal absorbents and sanguiferous vessels, be- fore it is completely assimilated. Chyme, from which this nutrient principle is obtained, is a compound of gastric juice and ahment. It may be regarded as a ^astrite of whatever it is combined with, varied ac- cording to the kind of aliment used. The perfect chyle, or assimilated nutriment, probably contains the elements of all the secretions of the system ; such as bone, muscle, mucus, saliva, gastric juice, &c. &c., which are separated by the action of the glands, the sanguiferous and other vessels of the system.

The action of the stomach, and its fluids, on ali- ment, is believed to be sui generis, invariably the same, in health, on all kinds. And yet it is contend- ed by Paris, and obliquely hinted by some other mo- dern physiologists, that as animal food " posseses a composition analogous to that of the structure it is designed to supply," it " requires little more than division and depuration," &c. It is singular that sensible men, and men of science, can allow them- selves to be led to such erroneous conclusions, and will not perceive a simplicity and uniformity in the process of digestion, as well as in all the other ope- rations of nature. That the active solvent of the stomach stiould produce the same effect on all ali- mentary substances, is no more wonderful than that caloric should liquefy all kinds of matter. In both cases it only requires a longer or shorter continuance, or more or less concentrated action, of the agent, to produce the sarn? effect. If anima! fcod is only

38

PRELIMINARY

to be divided and depurated, blood, which is an ele- mentary part of the body, would require no change in the stomach. But it is perfectly idle to talk in this way. The most innutritions vegetable and the most animalized substance, require the same action of the gastric solvent, as the reader will find amply demon- strated in the following experiments. It is true that one may be disposed of with ease, and the other with difficulty ; but this is not always, nor indeed often, in a direct ratio to their respective proportions of nu- trient principles. An innutritions diet may be dis- posed of as easily, the circumstances of divisibility and tenderness of fibre being equal, as a nutritious one. I do not beheve that the one requires a more " com- phcated series of decompositions and recomposi- tions" than the other; nor that the chyle from ani- mal aliment is more highly " animalized" than that from the poorest diet we possess. The " digestive fever," or the excitement that follows the digestion of animal food, is the eflect, not of a different kind of stimulus, but of the introduction of a greater quantiUj of chyle, or the nutritive principle of food, into the circulating fluids. It excites the system precisely in the same manner as ardent spirits. Or other stimulus does, with the exception, that its ef- fects are more permanent.

The quantity of nutriment required by different individuals, is as various as the individuals who par- take of it. As a general rule, it may be said that persons who do not exercise much, require less nu- tritious diet than those who are in the habit of con- stant labour. What would be a natural supply m.

OBSERVATIONS. 39

one, would be excess in another. With labouring persons, much of the excess is carried oft' by per- spiration ; and probably a great deal of nervous en- ergy is wasted by laborious occupations, which re- quires to be replenished by the nutrient principles of aliment. This is a subject, however, on which we can only offer conjecture ; for it is difficult to ar- gue on a point of which we know so little. Young people who are growing, require more nutriment in proportion to their size, than those who have arrived at adult age.

The quality of nutriment is a matter of consid- erable importance in dietetic regulations. Bulk is, perhaps, nearly as necessary to the articles of diet as the nutrient principle. They should be so managed that one should be in proportion to the other. Too highly nutritive diet is probably as fatal to the pro- longation of life and health, as that which contains an insufficient quantity of nutriment. It has been as- certained that carnivorous animals will not live on highly concentrated food alone. Dogs fed on oil or sugar, which are both converted by the digestive organs almost entirely into chyle, are found to be- come diseased, and die ui a few weeks. The infer- ence drawn by Paris,* that it merely " proves that an animal cannot be supported on highly concentrated aliment alone," no doubt, is a correct one ; though opposed to the opinion of Magcndie, the author of the experiments, who infers that death proceeds from the want of azote in these articles of diet, and that life cannot be supported on non-azotized aliment.

40 rRELlMINARV

The following articles of the materia alimentarm have, in the course of these experiments, been sub- mitted to the action of the stomach and the gastric fluids. I have attempted, in this table, to approxi- mate towards a comparison of the digestibility of the several articles there mentioned. Precision, as to minutes, has not been attended to. When digestion has been accomplished two or three minutes either before or after a certain number of hours and quar- ters, I have set down the quarter to which it ap- proached the nearest.

In a subsequent part of this volume 'a more parti- cular and minute detail will be found, both of natural and artificial digestion.

Explanation of the abbreviations in the following Ta- llc. — br'd, for bread — veg., for vegetables — mod., for moderate — inc., for increascd—susp'd, for suspended — dur'g, for during — cxp't, for experiment — h"rd bid, for hard boiled — h., for hour — m., for minute, &c. — The figures denote the time of digestion, under the circumstances mentioned at the head of the column-

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OBSERVATIONS. 45

Soup, made of fresh muscular fibre of bcof, and vegetables, do. made of the hock, with vegetables, Bread, buttered, for breakfast, with coft'ec ) [morbid appearance of stomach] \ do. butteied, for breakfast, with coflcc do. dry, for breakfast, with coffee, do. dry, for dinner, with dry mashed potatoes

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This Tabic is far from being complete. The ex- periments from which it has been formed, were made principally with the view of demonstrating other important principles connected with tlic subject of digestion. The only way of ensuring minuteness and accuracy as to the comparative digestibility of difter- cnt kinds of diet, would be to try the eifect of the gastric juice, in a series of experiments, first on one article of diet, and then on another, repeating and a- dapting them to meet all the various conditions of the stomach, and the vicissitudes and irregularities of the system, until the whole range should be comple- ted— a Herculean task, which it would take years to accomplish. In the above table, the time is counted from the reception of the meal of various articles to the chymification of the whole : hence the conclu- sions arc frequently indefinite, some of the articles being sooner disposed of than others. For instance, if a dinner be eaten of venison steak and fat pork, the time of digestion of the whole quantity would, in all probability, be twice as long as if venison had been used alone. Oily substances are digested with great difficulty, and the fat of all meats is converted into oil in the stomach before it is digested. Chymifica- tion is most readily effected on solid food, or rather

46

PRELIMINARY

on a soft solid, which is easily divisible into shreds or small particles. Such is particularly the character oi venison, which is ascertained to be one of the most digestible of substances. The qualities of looseness oftexture and susceptibility of division belong to most of those wild meats and game which are gene- rally acknowledged to be easy of digestion. Bcel and mutton, of a certain age, possess similar quali- ties.

The opinion advanced by Paris, *that the flesh of wild animals is more dense than the domesticated, does not correspond with the experience of those who are well acquainted with the former. Although, on making a section of wild flesh, such appearance may be indicated, yet the fibres are found to be more easily separated by mastication, or other force, and are generally tender ; at least, such is the case with the flesh of those animals that are considered luxuries by the epicure. Compare, for example, the flesh of the wether and the deer, animals which have a near correspondence in their habits, and the difference will be very obvious.

The digestibility of most meats is improved by in- cipient putrefaction, sufficient to render the muscular fibre slightly tender.

Vegetables are generally slower of digestion than meats and farinaceous substances, though they some- times pass out of the stomach before them, in an un- digested state. Crude vegetables, by some law o^ the animal economy, not well understood, are allow- ed, even when the stomach js in a healthy state,

Paris Od Diet, p. 72.

OBSERVATIONS. 47

sometimes to pass the pyloric orifice, while other food is retained there to receive the solvent action of the gastric juice. This may depend upon their com- parative indigestibility ; for it is well known that cathartic medicines, various fruits, seeds, &c. which operate as laxatives, are not digested ; are incapable of being retained in the stomach ; and pass rapidly through the intestinal tube. When such articles are in excess, they produce considerable derangement, and sometimes fatal consequences.

Vegetable, like animal substances, are more capa- ble of digestion in proportion to the minuteness of their division, as I have before remarked, provided they are of a soft solid ; and I cannot, therefore, concur in the opinion expressed by Paris,* that potatoes are better when only boiled so as to be rendered tender, and have their shape preserved, than when boiled to a " dry, insipid powder." They may be more palata- ble, and contain more nutriment ; but they are not so easily affected by the gastric solvent. The difference is quite obvious on submitting parcels of this vegeta- ble, in different states of preparation, to the operation, of the gastric juice, either in the stomach or out of it. Boiled, or otherwise cooked to dryness, so as to be easily mashed, potatoes very readily become reduced to a chymous state, when submitted to the action of the gastric juice. When differently prepared, and on- ly boiled so as to be rendered barely soft, moist and tenacious, with the shape preserved, entire pieces re- main long undissolved in the stomach, and very slowly yield to the action of the gastric juice in vials

Paris On Diet, p. 75,

48 rnELIMINARV

on the bath. Pieces of raw potato, when 8ul>mittcd to the operation of this fluid, in the same manner, al- most entirely resist its action. Many hours elapse before the slightest appearance of digestion is observ- able, and this only upon the surface, where the ex- ternal lamina) become a little softened, mucilagi- nous, and slightly farinaceous. Every physician, who has had much practice in the diseases of children, knows that partially boiled potatoes, when not suffi- ciently masticated, (which is always the case with children.) arc frequently a source of colics and bowel complaints, and that large pieces of this vegetable pass the bowels untouched by digestion.

These remarks will apply, also, to most other ve. getable aliment.

The variety of fish, which are generally used by the citizens of this country, may be regarded as easi- ly susceptible of digestion. The lobster, crab, and some others of the testaceous tribe, are, perhaps, ex- ceptions.

Solid food is sooner disposed of by the stomach than fluid, and its nutritive principles are sooner car- ried into the circulation. It has been observed, how- ever, that the exhaustion from abstinence is quicker removed by liquid than solid aliment. This is un- doubtedly true ; and it may be accounted for on the ground of a general sympathy existing between the stomach and all the other parts of the body. It is only necessary, in proof of this fact, to appeal to the experience of almost every pliysician. The violent spasms, contortions, kc. afl'ecting different and re- mote parts of the system, that sometimes supervene

OKSERVATIONS.

4d

on the introduction of crude or indigestible food in- to the Btomach, are pretty clear indications of the powerful sympathy that exists between it and other organs or apparatuses.

Condiments, particularly those of the spicy kind, are non-essential to the process of digestion, in a healthy state of the system. They aftbrd no nutri- tion. Though they may assist the action of a de- bilitated stomach for a time, their continual use ne- ver fails to produce an indirect debility of that organ. They affect it as alcohol or other stimulants do — the present relief afforded is at the expense oi future suffering. Sah and vinegar are exceptions, and arc not obnoxious to this charge, v/hen used in modera- tion. They both assist in digestion — vinegar, by rendering muscular fibre more tender — and both to- gether by producing a fluid having some analogy to the gastric juice.

Drinks are nearly as essential to the animal sys- tem as the more substantial food. Though not sub- ject to digestion, they enter into the circulation, and become important agents in the ultimate changes that are undergoing in the tissues of the organism. Simple water is, perhaps, the only fluid that is called for by the wants of the economy. The artificial drinks are probably all more or less injurious ; som© more so than others ; but none can claim exemption from the general charge. Even coffee and tea, the common beverages of all classes of people, have a tendency to debilitate the digestive organs. Let any one who is in the habit of drinking either of these articles in a weak decoction, take two or three cups G

rxO

FRELIMINARY

made very ^troivg, and he will soon bo awaro of theft injurious tendency. And this is only an addilion to iJie strength of the narcotic lie is in the constant habit of using. The whole class of alcoholic liquors, whether simply fermented, or distilled, may be con" sidered as narcotics, producing very little difl'ercnce in their ultimcate effects on the system.

The injury which a constant use of wine is known to produce on some stomachs, has been sometimes at- tributed to the small quantity of tartaric acid which it contains. But i^jis not the cream of tartar that renders wine so deleterious to many stomachs. It is the acidity produced by the acetous fermentation of the saccharine matter contained in the wine, aided, perhaps, by the alcohol which is in a state of combi- nation with it. Beer has the same effect on the same idiosyncracies, or diseased states of the sto- mach. Besides, both of these fluids are in a partial stage of acetous fermentation, which is consummated by the increase of temperature in the stomach.

It would be a task of great difficulty to designate the exact kind of diet that would, if generally adopted, be the most conducive to health and longevity. A considerable variety seems to be necessary to man, in a state of civilization. This want of variety is in- duced by long habit, which it would probably be un- safe to break through. Whether man was originally carnivorous or granivorous, is a question which we cannot solve, and perhaps it is not worth the at- tempt ; at present he is both, and witli his present mode of existence we have to do.

OBSERVATIONS 51

I

The quantiiy of aliment is probably of more im- portance than the quality, to ensure health. The system requires much less than is generally supplied to it. The stomach disposes of a definite quantity- If more be taken than the actual wants of the econo- my require, the residue remains in the stomach, and becomes a source of irritation, and produces a con- sequent abberration of function, or passes into the lower bowels in an undigested state, and extends to them its deleterious influence. Dyspepsia is oftener the effect of over eating and over drinking than of any other cause.

SECTION II.

Of Hunger and Thirst.

HUNGER is a painful sensation, referred to the region of the stomach. It is a kind provision of na- ture, designed to remind man, and other animated beings, of the necessity of replenishing the wastes of the system, as well as contributing to its growth. Much enquiry has been made on this subject, and many theories have been given to account for the phenomenon. It has been supposed by some, that the friction of the internal coats of the empty sto- mach was the cause of the sensation. This opinion is liable to several objections: — 1st. A healthy sto. mach digests its contents in from one to three or four hours, and hunger is not usually experienced until some time after the latter period. If hunger be the effect of the friction of the parieties of the stomach, it ought to be experienced the moment that that or- gan has disposed of its contents. 2d. In nausea and vomiting, the stomach is brought into a situation, according to this theory, to experience the sensation of hunger ; and yet we know how opposed it is to receiving any thing like food. 3d. In gastritis and

54 PRELIMINARY

fevers the sensation hardly ever occurs, though very httle food shall have occupied the stomach for a long time — perhaps not for weeks. This organ, under such circumstances, is generally empty and irritable, yet the pecuhar sensation in question hardly ever supervenes. Besides, hunger sometimes occurs when the stomach is partially or wholly filled. The pota" tion of spirits or brandy and water, and some other indigestible substances of a liquid character, does not remove the sensation, although by this means the parieties of the stomach are as completely sepa- rated as by food.

It has also been suggested that the sensation of hunger is produced by the irritation of a quantity of gastric juice in the stomach, which, by its stimulus, excites the feeling. The principal objection to this doctrine is based upon the fact that the stomach con- tains no gastric juice, or, at any rate, but a very small quantity, in its empty state, or when aliment or other irritant is not present. Besides if it were true that it contained a quantity of the fluid, such fluid does not possess the power of producing any thing like ir- ritation or inflammation of its coats. It is as innox- ious to the stomach, as the blandest substance in na- ture. It exerts its influence on free aliment, but not on the living fibre.

By referring the sensation to " an energetic state of the gastric nerves, occasioned by an interval of in- activity, during which the vital powers may be sup- posed to accumulate,"! it appears to me that we are venturing upon unexplored gr ounds ,of which we know

} Pam 0.: D\ei, p. 55.

OBSERVATIONS. 55

but little. We are not accustomed to call those pairt^ ful nervouiJ sensations to which the system is some- times subject, states of high nerfous energy. Are they not rather states of nervous debility } or, at any rate, irregular and unhealthy motions?

That the introduction of narcotics into the stomach should destroy the appetite, proves only that they have the same effect on that organ as they have on other parts of the body ; they paralyse the nerves, and render them incapable of being the media of com- munication to theiy common centre.

Many other causes have been assigned for this sensation, equally wide, probably, of the true one. It has been attributed to the " foresight of the vital principle," a phrase that means any thing, every thing, or nothing, according to the construction which each one may put upon it. Such explanations conduce nothing to the promotion of science. They are mere sounds and words, which ingeniously con- vey a tacit acknowledgement of their author's ig- norance.

Again, the mechanical action of the hver upon the diaphragm, has been accused of producing the sen- sation of hunger. Some proof, more than mere as- sertion, is necessary to convince honest enquirers that so remote a cause should produce such effects on the stomach, the immediate seat of the feeling. Of the same nature, is the opinion of the fatigue of the contracted fibres of the stomach, or of compression of the nerves of that organ, &c. &c.

Magendie, convinced that all the theories on this subject were unsatisfactory, comes to the following

06 PRELIMINARY

comprehensive conclusion : that " Hunger is produ- ced like all other internal sensations, by the action of the nervous system, and it has no other seat than in this system itself, and no other causes than the general laws of organization."t I cannot perceive that such explanations bring the mind to any satis- factory understanding of the subject. In such broad propositions, it is difficult to ascertain the exact meaning. If the design is to convey the impression that hunger has no " local habitation ;" that it is an impression, affecting all the nerves of the system in the same manner ; then the sensation would be as likely to be referred to one organ as another. It is true, that without nervous communication there would be no sensation at all. This applies as well to other parts as to the stomach. The nerves are the media of communication from the sensible parts to the centre of perceptions. They warn the encephalon not only of the injuries, but of the wants of the tissues. We are accustomed to refer local sensations and irritations to the parts apparently af- fected— desire for urination and defecation, to the bladder and rectum ; for liquids, to dryness of the mouth and fauces : and we account, in like manner? for other physiological and pathological sensations* When we can arrive at the exact interpretation of an author, who says that hunger has " no other causes than the general laws of organization," it will then be time to give reasons for an assent to or dissent from the proposition.

tSuomary of Physiology, f. 196.

OBSERVATIONS. •')?

This subject is, unquestionably, involved in con. •siderable doubt and obscurity, and will not, it is to be apprehended, admit of a very speedy elucidation. The Author of Nature is perfect in all His works ; and although we may not understand all the opera- tions of His hands, we are compelled to acknowledge their wisdom, propriety and beauty. Man would be miserable and wretched indeed, if he depended solely on his own discretion and judgment to decide upon the quantity and quality of aliment necessary to supply the wastes, and administer to the growth, of the sys- tem. This paucity of judgment and discretion is, however, more than compensated by an irresitible sensation, which indicates the proper time for the re- ception of food. The immediate cause of this sen- sation, as we have seen, has not as yet received a very satisfactory explanation, and perhaps will not admit of one. But, although confessedly obscure, we are not denied the privilege of patient investiga- tion, and persevering search after truth. Knowledge is progressive, as well in this as every other science ; and every new discovery, and every rational hypo- thesis, are additions to the general stock. Persua- ded of the truth of these general propositions,, and anxious mainly to elicit investigation on the subject, I submit the following Theory of Hunger, believing it to be as reasonable, to say the least, as any that has been propagated.

My impression is, that the sensation of hunger is produced by a distention of the gastric vessels, or that apparatus, whether vascular or glandular, which si?- H

58 PUELIMINARY

cretes the gastric juice; and is believed to be the ef- fect of repletion by this fluid.

One reason, among others, for this belief, is the established fact, tliat the internal sensations referred to different organs, as has been previously alluded to, are caused by some modified action or condition of the parts in the tissues of the organ itself The modification in the parts to which the sense of hun- ger is invariably referred, I conceive to be a disten- tion, by the gastricjuice, of a particular set of vessels or glands, constituting, in part, the erectile tissue of the villous coat of the stomach. The sensation va- ries according to the different degrees or states of distention, from the simplest desire to the most painliil sense of hunger ; and is allayed or increased in proportion to the application, or refusal, of ali- mentary stimulus to the excretory vessels. The greater the distention of the vessels, the more acute will be the pain : hence, the differenc e between a short and protracted fast. Appetite and hunger be- long to the same class of sensations ; they differ on- ly in degree. In this they are like all other sensa- tions. A little increased circulation in the vessels of the brain produces peculiarly vivid, but not abso- lutely unpleasant feelings, and gives force and ener- gy to the mental volitions : carried further, it produ- (jes most painful sensations. It is unnecessary to cite further examples. Indeed, it does not need ar- guments to prove what is the subject of every day's observation. It is well known that the pain from acute inflammation is produced by distention of the blood vessels. Let anj one, who is disposed tg try

OBSERVATIONS. 59

the effect of vascular distention, place a ligature arbund the finger or arm, sufficiently tight to retard the returning blood, and the truth will be sufticicntly obvious.

It is, therefore, inferred from the pain, (and no one, it is believed, will deny that hunger is a painful sen- sation, whatever may be his opinion oi appetite) that vessels of some kind are distended ; and it is demon- strated, I think, in some of the following experiments, that these are the gastric vessels. On applying ali- ment to the internal coat of the stomach, which, in health, is merely lubricated with mucus, innumerable minute papilte, the orifices, undoubtedly, of the gas- tric vessels, immediately throw out a quantity of tlie fluid, which mixes with the food. This efiect is too sudden, and the secretion too copious, to be account- ed for on the ordinary principles and laws of secre- ting mucous surfaces. The quiescence and relief from the unpleasant sensation, which are experienced as soon as the vessels are emptied, are, I think, ad- ditional proofs of my opinion. It is certain, that at the introduction of every meal, or on the application of alimentary stimulus to the internal coat of the sto- mach, a very large secretion of a fluid, which has repeatedly been ascertained to be an alimentary sol- vent, immediately takes place ; and that when the stomach is destitute of food or some other irritating substance, no such secretion can be found in it. And it is more than probable — it, in fact, almost amounts to demonstration, that a large quantity of this fluid must be contained in appropriate vessels, during a fast, ready to obey the call of aliment. I would not

fiO PRELIMINARY

be understood to say that the wliolc quantity neces- sary for an ordinary meal is eliminated from the blood, previous to the commencement of alimenta- tion ; but that enough is contained in tlie gastric vessels to produce the sensation of pain or hunger.

If it be objected to this theory, that the vessels would become ruptured, or empty themselves into the cavity of the stomach, during a long fast, I re. ply, that this apparatus is probably constituted like many of the other organs of the system, and permits the absorption of its secretions by the lym- phatic or other absorbent vessels. The male semen is constantly being secreted, and deposited in its proper seminal vessels, ready to be ejected during the venerial orgasm ; and yet how many men live for years, or perhaps for a whole life, who have no in- tercourse with the other sex. What becomes of the semen under these circumstances .'* Taken up, un- questionably, by the absorbing vessels, as the gastric juice of the stomach is.

I ofter this theory for consideration, persuaded that the public will allow it such weight as it may have a right to claim : more than this, I have no wish to ask

Thirst. — This sensation is felt in the mouth and fauces.. Like hunger, it is a kind provision of na- ture, designed to remind men and animals of the ne- cessity, not of replenishing the wasting solids of the system, but of diluting the fluids that arc carrying on these processes. Although Magendie has attempted to put a stop to all inquiries on this subject, in the remark, that " Thirst is an internal sensation, an in- stinctive sentiment ;" " the result of organization, and

OBSERVATIONS. 61

does not admit of any explanation;" I apprehend a remote cause of this sensation may be found in the viscidity of tlic blood, which requires a liquid to ren- der it more fluid, and more susceptible of introduc- tion into the capillaries and secreting surfaces. The proximate cause may exist in an irritation, a kind of sub-inflammation of the mucous membranes of the mouth and fauces, the effect of the viscid state of the blood, and consequently impervious state of the se- cretory vessels of these membranes. The sensation of dryness, or thirst, is supposed to be the effect of evaporation, the mouth and throat being constantly exposed to the atmosphere. When there is sufficient fluidity of the blood, the secretion is so much more copious than the evaporation, that a constant mois- ture is preserved. The sensation of thirst resides in the tissues ; and it is no more " an instinctive senti- ment" than any other sensation of the economy. To say that it is the " result of organization," gives no explanation, amounts to nothing, and is certainly, to say the least, a very unsatisfactory way of disposing of the question.

SECTION III.

Of Satisfaction and Satiett.

IN the present state of civilized society, with the provocatives of the cuhnary art, and the incentives of high seasoned food, brandy and wines, the tempt- ations to excess in the indulgences of the table are rather too strong to be resisted by poor human na- ture. It is not less the duty, however, of the watch- men on the walls to warn the city of its danger, how- ever it may regard the premonition. Let them at least clear their own skirts from the stain of unfaith- fulness, whatever may be the result.

There is no subject of dietetic economy about which people err so much, as that which relates to quantity. The medical profession, too, have been ac- cessory to this error, in giving directions to dyspep- tics to eat until a sense of satiety is felt. Now, this feehng, so essential to be rightly understood, never supervenes until the invalid has eaten too much, if he have an appetite, which seldom fails him. Those, even, who are not otherwise predisposed to the com- plaint, frequently induce a diseased state of the di- gestive organs by too free indulgence of the appetite. Of this fact the medicfil profession arc, general lv» fliot

6t CRELIMmARY

sufficiently aware. Those who load sedentary lives., and whose circumstances will permit of what is call- ed free living, are peculiarly obno.xious to these com- plaints. But by paying particular attention to their Sensations during the ingestion of their meals, these complaints may be avoided. There appears to be a sense of perfect intelligence conveyed from the sto- mach to the encephalic centre, which, in health, in- variably dictates what quantity of aliment (respond- inf to the sense of hunger, and its due satisfaction,) is naturally required for the purposes of life ; and which, if noticed, and properly attended to, would prove the most salutary monitor of health, and effec- tual preventive of, and restorative from, disease. It is not the sense oUaticly, for this is beyond the point of Aca//A/«/ indulgence, and is nature's earliest indication of an ahuse and overburthen of her powers to replenish the system. It occurs immediately previous to this, and may be known by the pleasurable sensation of perfect satisfaction, ease and quiescence of body and mind. It is when the stomach says oiough, and is distin- guished from satiety by the difference of the sensa- tions— the former feeling enough — the latter, too much. The first is produced by the timely reception into the stomach of proper aliment, in exact proportion to the requirements of nature, for the perfect diges- tion of which, a definite quantity of gastric juice is furnished by the proper gastric apparatus. But to effect this most agreeable of all sensations and con- ditions— the real Elysian satisfaction of the reasonable Epicure — timely attention must be paid to the pre- liminary processes, such as thorough mastication, and

0B8EIIVAT10NS.

Gi

moderate or slow deglutition. Tiiese arc indispen- sable to the due and natural supply>f the stomach, at the stated periods of alimentation ; for if food be swallowed too fast, and pass into the stomach imper- fectly masticated, too much is received in a short time, and in too imperfect a state of preparation, to he disposed of by the gastric juice.

The quantity of gastric juice, either contained in its proper vessels, or in a state of preparation in the circulating fluids, is believed to be in exact proportion to the proper quantity of aUment required for the due supply of the system. If a more than ordinary quan- tity of food be taken, a part of it will be left undissolv- ed in the stomach, and produce the usual unpleasant symptoms of indigestion. But if the ingestion of a large quantity be in proportion to the calls of nature, •.which sometimes happens after an unusual absti- nence, it is probable that more than the usual supply of gastric juice is furnished ; in which case the appa- rent excess is in exact ratio to the requirements of the economy; and never fails to produce a sense of quiescent gratification, and healthful enjoyment- A great deal depends upon habit, in this respect. Our western Indians, who frequently undergo long abstinences from food, eat enormous quantities, when they can procure it, with impunity.

Satietij is produced by tendering too much at once for the wants of tlie economy ; more than the gastric juice is able to dispose of at the time ; dis- tending the muscular fibres beyond that point so ad- mirably fixed, by the invariable and universal laws of the animal system, for agreeable sensations ; disturb-

66 PRELIMINARY

ing the peculiarly pleasurable, undulatory motions of the ruga) of the stomach, in their operations of form- ing chyme ; and perhaps, interrupting, if not dimin- ishing, the secretion of the gastric juice. The re- dundant aliment, incapable of being dissolved, for want of sufficient gastric juice, remains, and becomes a source of irritation, and renders imperfect the chymi- fication of that which would otherwise have been com- pleted. Hence the sense of weight, and disagreeable fulness, attendant on an unusually hearty meal ; the subsequent derangement of the digestive functions, and consequent acidities and vitiated contents of the prima via3, from acetic fermentation in the sto- mach, and imperfect formation of chyle in the intes- tines.

SECTION IV.

Of MasticatioiV, Insalivation and Deolutition.

THESE are the preliminary steps in the process of digestion. The comparative importance of these processes has been elevated or depressed, accord^ ing to the preponderance which each of them may have received from the opinions of the different physiologists who have made them subjects of obser- vation. As man and animals are constituted, they are all absolutely necessary to the digestion of food. But in an abstract point of view, disconnected as a mean of introducing ingestas into the stomach, I believe I hazard nothing in saying that they may be consider- ed as perfectly non-essential to chymification. If the materia uUmentaria could be introduced into the sto- mach in a finely divided state, the operations of mas- tication, insalivation and deglutition, would not be necessary. Aliment is as well digested and assimi- lated, and allays the sensation of hunger as perfectly, when introduced directly into the stomach, in a pro- per state of division, as when the previous steps have been taken, as may be seen by some of the^following experiments. If particular importance is to be attri-

68 PRELIMINARY

butcd to any of these previous steps, it is certainly due to mastication ; though an undue importance has, of late, been given to the action of the saliva. Professor Jackson, of Philadelphia, who has lately published a physiological work on the " Structure and Functions of the Animal Organism," has elevated saliva to a rank in the process of digestion, seldom before claim- ed for it. He considers it the principal solvent, or ma- cerating agent, of alimentary matter. He is sustained in this opinion by Montegre and others. Even Magen- die is inclined to favour this belief

It is remarked by Paris, (On Diet, p. :57,) that the introduction of saliva into the stomach is " obviously essential to a healthy digestion." That it is general- ly introduced into the stomach with the food is very obvious ; the nature of its action is not so clear. In most of the experiments that follow, artificial diges- tion was performed without the admixture of saliva- Chyme formed in this way, exhibited the same sensi- hle appearances, and was affected by re-agents in the same way, as that which was formed from food which had been previously masticated, mixed with the sali- va, and swallowed. It would seem, from two or three of the experiments on artificial digestion, which were instituted for the purpose of comparison, that the mixture of saliva with the gastric juice rather re- tarded its solvent action. But I do not wish to deny the utility of the saliva. It is certainly important as a preliminary to digestion. Its legitimate and only use, in my opinion, is to lubricate the food, and to facilitate the passage of the bolus through the organs of deglutition. In this point of view, it is essential.

OBSERVATIONS.

69

Dry food cannot be swallowed until it receives an admixture of a fluid, whether it be saliva or some other liquid, is not, I conceive, a matter of much im- portance. Any one, disposed to try the experiment, may satisfy himself of this fact, by attempting to swallow a mouthful of dry cracker, meal or magne- sia. He will find it impossible to make the organs of deglutition act till a quantity of fluid is mixed with it. Water will answer the purpose, nearly as well as saliva ; though the mucous properties of this secre- tion may give it a slight preference.

Pathology is not, in my opinion, much indebted to Ruysch, who attributed the loss of appetite to the waste of saliva in a person who was afflicted with a fistula in one of the salivary ducts ; nor to the opinion advanced by others, that the constant spitting of ma- niacal patients, induces loss of appetite. The truth is, that in both cases, the effects are attributed to the wrong causes. There is no difliculty in believing that a foul ulcer in the mouth would be liable to produce nausea and want of appetite ; nor that maniacal pa- tients are generally, if not always, aflected with dis- eased organs of digestion. I have known many per- sons to spit freely and constantly, whose appetites and digestion were perfect. Those who smoke tobacco are constantly discharging large quantities of sahva ; and yet I am not aware that dyspepsia is more com- mon with them than with others.

I entirely dissent from the opinion advanced by the author above referred to, (Paris,) that " Insalivation is as essential as mastication." The use of mastica- tion is to separate the food into small particles, so

70 PRELIMINARY

that the solvent of the stomach may be applied to a greater extent of surface. Tiierc is no mystery about this. Every body knows that the smaller the parti- cles of matter that are submitted to the action of a chemical agent, the more vigorously the agent will act upon them, and the sooner they will be dissolved, or decomposed.]: Mastication is absolutely necessa- ry to healthy digestion. If aliment, in large masses, be introduced into the stomach, though the gastric juice may act upon its surface, chymification will proceed so slowly, that other changes will be likely to commence in its substance before it will become completely dissolved. Besides, the stomach will not retain undigested masses for a long time, without suf- fering great disturbance. It is governed by certain laws with respect to aliment. After food has been retained for a certain length of time undigested, say from five to ten hours, according to the healthy or diseased state of that organ, or the quantity received into it, it is either rejected by vomiting, or is permit- ted to pass into the duodenum and lower bowels, where its pr|sence almost invariably produces colic flatulence, &c. When the stomach is unusually debilitated, food, however, is frequently retained for twenty-four hours or more, and is sometimes the cause of most distressing symptoms, producing, par- ticularly in children, convulsions and death. I there- fore consider mastication as one of the most impor- tant preliminary steps in the process of digestion.

J Inusiogthe word solvent or solulion, id reference to (he gastric juice, I wish tg be understood to mean a chemical action, analogous lo that of tlie action of mine- ral acids on the metals ; nol like the solulion of sugar or salt in water.

OBSERVATIONS 71

With respect to deglutition, I shall make but a, few remarks. It is important for the preservation of health, that this process should be effected slowly. If food be swallowed rapidly, more will generally be taken into the stomach before the sensation of hunger is allayed, than can be digested whh ease. If due at- tention be paid to the previous step of thorough mas- tication, we shall not be so likely to err in this later one.

Swallowing very rapidly, produces irregular con- tractions of the muscular fibres of the oesophagus and stomach ; disturbs the vermicular motions of the ru- gae, and interrupts the uniform action of the gastric apparatus.

The stomach is not designed to receive more food than can be duly mixed with the gastric solvent, al- ready in its proper vessels, or in a state of preparation in the blood vessels. Perfect harmony of action must exist throughout the whole apparatus, or derange- ment of healthy action will ensue.

The stomach will not admit of the introduction of food, even of a liquid kind, through the aperture, at a rapid rate. If a few spoonfuls of soup, or other li- quid diet, be put in with a spoon or funnel, the rugas gently close upon it, and gradually diffuse it through the gastric cavity, entirely excluding more during this action. When a relaxation takes place, another quan- tity will be received in the same manner.

If the valvular portion of the stomach be depress- ed, and solid food be introduced, either in entire pieces, or finely divided quantities, the same gentle contraction, or grasping motion, takes place, and

12

PRELIMINARy

continues for fifty or eighty seconds ; and will not al- low of the introduction of another quantity until the above time has elapsed ; when the valve may again be depressed, and more food be put in. Food and drinks will be received through the aperture no faster, even when the stomach is entirely empty, than they are ordinarily received through the oesophagus. When the subject of these experiments is so placed that the cardia can be seen, and he be allowed to swallow a mouthful of food, the same contraction of the stomach, and closing upon the bolus, is invaria- bly observed to take place at the oesophageal ring.

SECTION V.

Of Digestion by the Gastric Juice.

CHYMIFICATION is effected in the stomach. It is the first stage, proper, of the conversion of aUment into blood; though in the ordinary course of proceed- inff, as animals are constituted, some previous steps are necessary. After the aliment has been receiv- ed into the stomach, it is subjected to certain evo- lutions, or motions, propagated by the muscular fi- bres of that organ ; and is acted upon through the agency of some principle, which changes it from a heterogeneous mixture of the various kinds of diet, submitted to its action, to an uniform, homogeneous semi-fluid, possessing properties distinct from the elements of which it was composed. The length of time consumed in the operation is various. It de- pends upon the quantity or quality of the ingestae, the healthy or diseased state of the stomach, &c. In the various experiments which I have made, the me- dium time may be calculated at about three and a half hours.

It has been suggested by many physiologists, and positively asserted by some, that there is considera- K

74

PRELIMINARY

ble increase of the temperature of the stomach du" rnig the digestion of a meal. But from the result of a great number of experiments and examinations, made with a view of ascertaining the truth of this opinion, in the empty and full state of the organ, and during different stages of chymification, I am con- vinced that there is no alteration of temperature, un- less some other circumstance should produce it. Ac- tive exercise always elevates the temperature of the stomach, whether fasting or full, about one and a half degrees.

With respect to the agent of chymification, that principle of hfe which converts the crude ahment in- to chyme, and renders it fit for the action of the he- patic and pancreatic fluids, and final assimilation and conversion into the fluids, and the various tissues of the animal organism — no part ofphysiology has, per- haps, so nduch' engaged the attention of mankind, and exercised the ingenuity of physiologists. It has been a fruitful source of theoretical speculation, from the father of medicine down to the present age. It would be a waste of time to attempt to refute the doc- trines of the older writers on this subject. Suffice it to say, that the theories of Concoction, Putrefaction Trituration, Fermentation and Maceration, have been prostrated in the dust before the lights of science and the deductions of experiment. It waS reserved for Spallanzani to overthrow all these unfounded hy- potheses, and to erect upon their ruins, a theory which will stand the test of scientific examination and experiment. He established a theory of chemical SOLUTION, and taught that chymification was owing

OBSERVATIONS. 75

to the solvent action of a fluid, secreted by the sto- mach, and operating as a true menstruum of ahmen" tary substances. To this fluid he gave the name of Gastric Juice. It does not come within the scope of this work to give a detail of the experiments and reasoning which wrought conviction in the mind of this great man. It is only necessary to say that it was the result of patient and persevering experiment and research.

The truth of Spallanzani's theory has been sustain- ed, so far as relates to the most important part, the existence of a chemical solvent, by all who have made fair examinations and experiments on the sub- ject. The experiments of Tiedemann and Gmelin, of Leuret and Lassaigne, confirm the same theory.

By far the most respectable and intelligent phy- siologists have now settled down in the behef that chymification is effected in the stomach, by a peculiar and specific solvent, secreted in that organ, called, after Spallanzani, the Gastric Juice. From the diffi- culty, however, of obtaining and submitting such fluid to the test of experiment, and the diversity of results in the examination of such as has been obtain, ed, much indefiniteness is experienced on this sub- ject. The presence of an active solvent is rather an admission on their part — a conclusion from the effect to the cause. Broussais, speaking on this subject, says : " It remains for us to know whether the por- tion of mucous membrane, belonging to the stomachy contains secretory org;,;is, the office of which is to furnish a fluid, fit to produce the assimilation of nu- tritive substances." And, again, speaking of the gas-

76 PRELIMINART

trie juice, " The question is as yet undecided, though, if we are to judge by analogy, we shall observe that many animals are furnished with gastric glands, sup- plying a digestive liquid." This author admits the presence of a solvent fluid in the stomach, without, however, attempting to explain its specific eflects, or mode of operation ; for he says, in another place, "We have expressed our opinion on this subject; but whether the gastric fluids possess an assimilating property, which, for ourselves, we admit, without pretending to demonstrate its actual presence," &c.

RicHERAND, BosTocK, aud ucarly all the authors of modern date, teach the doctrine of digestion by the gastric juice, without, however, pretending to explain its exact mode of operation. Professor Dunglison, whose work on " Human Physiology," taken as a whole, is, perhaps, the most comprehensive, arrives at the same conclusion. He says, " We have too many evidences in favour of the chemical action of some secretion from the stomach during digestion, to per. mit us to doubt for a moment of the fact." And, a- gain — " From all these facts, then, we are justified in concluding that the food in the stomach is subjected to the action of a secretion, which alters its proper- ties, and is tlie principal agent of converting it into chyme."

I have referred to these learned authors with the view of showing the exact state of the science on this subject.

Though the theory of chyniiftoation by the gastric juice, has become almost universal with physiologists* and the medical profession in general, still there

OBSERVATIONS.

77

are some, even of very modern date, who, with all the lights of science and experiment, from aversion to the slow and tedious processes by which truths are at- tained, or, perhaps, from the ambition of becoming the discoverers of some new and extraordiny process, or the projectors of some fanciful theory, deny the power of the gastric juice, or even the existence of such a fluid ; and set at naught the experiments, ob- servations and opinions of the ablest physiologists, and most experienced Avriters on this subject.

That chymification is effected by the solvent action of the ffastric juice, aided by the motions of the sto- mach, and the natural warmth of the system, not a doubt can remain in the mind of any candid person, who has had an opportunity to observe its effects on alimentary substances, or who has the liberality to credit the opinions of those who have had such op- portunities.

It has been objected to this hypothesis, that the sensible properties of the gastric juice contradict the opinion of its active solvent effect. But we should recollect that many things which make very little impression on our external senses, produce most as- tonishing effects in other situations. The air which we breathe, by which we are surrounded, and which, to our external senses, is almost inappreciable, is one of the most powerful and destructive agents in na- ture— one portion of which is capable of combining with all grades of matter, either slowly and imper- ceptibly, as in the gradual decay of all substances, or rapidly, as in the combustion of wood, or even the hardest metals — and which by means, inexplicable to

78

PRELIMINART

US, sustains in life and being the whole of animated nature.

The gastric juice has been submitted to chemical examination and analysis, with various results. Per- haps in the present state of the science of chemistry it will not be practicable to ascertain its exact chem- ical character. The parcels heretofore submitted to analysis, have been very impure ; but the result of even these partial examinations, has been to show that this fluid contains a portion of free muriatic acid, combined with the acetic, and some salts. In the winter of 1832-3, I submitted a quantity of gas- tric juice, with no other admixture, except a small proportion of the mucus of the stomach, to Profes- sor DuNGLisoN, for examination, who, with the assist- ance of the professor of chemistry of the Virginia University, effected the following analysis, and was kind enough to communicate the result to me by letter.

" University qf Virginia, Feb. 6th, 1833. " My Dear Sir,

" Since I last wrote you, my friend and col- league. Professor Emmett, and myself, have examin- ed the bottle of gastric fluid which I brought with me from Washington, and we have found it to con- tain free Muriatic and .Acetic acid, Phosphates and Muriates, with bases of Potassa, Soda, Ma<snesia and Lime, and an animal matter, soluble in cold water, hut insoluble in hot. We were satisfied, you recollect in Washington, that free muriatic acid was present but I had no conception it existed to the amount met with in our experiments here. We distilled the gas- tric fluid, when the free acid passed over ; the salts and animal matter remaining in the retort. The.

OBSERVATIONS. 79

<]uantity of Chloride of Silver thrown down on the ad* ditionof the Nitrate of Silver, was astonishing."

I had been long convinced of the existence of free muriatic acid in the gastric fluids. Indeed, it is quite obvious to the sense of taste ; and most chemists agree in this, however they may be at variance with respect to the other constituents. The analysis of Profes- sors DuNGLisoN' and Emmett is certainly as satisfac- tory as any that has as yet been made. It is a ques. lion, too, whether gastric juice, in so great a state of purity, has ever befote been submitted to chemical analysis.

It is to be hoped that no one will be so disingenu- ous as to attribute to Professor Dunglison the design of finding the existence of certain chemical agents in the gastric juice, with the view of propping the theory of the chemical action of this fluid, which he has maintained in his work on " Human Physiolo- gy ;" — or, in other words, to say, that he had deter- mined to find certain results ; and that he had ac- cordingly found them. Those who are acquainted with him, know that his candour and fairness are a- bove the reach of suspicion ; and that he would bc equally willing to retract a false opinion as to main- tain a correct one. Another quantity was sent to him for further analysis ; but I regret that no report has yet been received from him.

In April of the present year, (18.33,) a parcel was submitted to Benjamin Silliman, M. D. Professor of Chemistry in Yale College. Professional engage*

TREHMINART

ments prevented his examination of the fluid until the 2d of August, when he sent me the following result :

" Examituxlion. of the Gasiric Fluid, Aug. 2, 1833.

" 1. The Fluid, after being kept in a closely cork- ed vial, more than three months, from April to Au- gust, and mostofthe time in a cellar, remained unal- tered, except the formation of a pellicle upon the sur- face, slightly discoloured by red spots. A second pellicle appeared after the precipitation of the first. It was thicker, and more discoloured with dark red spots, hke venous blood.

" 2. The Fluid was cloudy, like a solution of gum arable ; but on filtering, it became perfectly clear, and of a slight, straw yellow tinge.

" 3. The pellicles, which had the appearance of inspissated mucus, after being separated from the Fluid, became, after exposure^o the air, throughout of a brownish red colour,, resembling the inner por- tion of a mass of coagulated blood. This change seemed tp result from a sudden oxygenation.

" 4. The Fluid exhaled a slight odour — not disa- greeable— rather aromatic — and very similar to that which it at first exhaled ; but not so strong. It was then rather disagreeable.

" .5. Taste, feebly sahne— not disagreeable.

" 6. Test papers of litmus, alkanet. and purple cabbage, were decidedly reddened. Turmeric pa- per underwent no change : but when previously brown- ed by an alkali, (ammonia) the gastric fluid restored the yellow colour.

" 7. Nitrate of Silver gave a dense white precipi- tate,, which, after standing five minutes in the sun's light, turned to a dark, brownish black ; thus indi- cating Muriatic Acid. Mur. and Nit. Barytes gave a slight opalescence, indicating a trace of sulphuric acid; not improbably, there was also somephospho- tic acid.

OBSERVATIONS. 81

" 8. Specific gravity — when taken in a small, thin glass tube, containing 201 grs. of distilled water — when filled with the gastric fiuid, its weight was in- creased 1 gr. — weight of the gastric liquor, there- fore, 202 grs. The specific gravity is, therefore, about 1.005. But little sohd matter in solution."

At the instance of Professor Silliman, I committed to the care of Mr. Gahn, Consul of his Swedish Ma- jesty in New-York, a bottle, containing one pint, of gastric juice, to be transmitted by him to Professor Berzelius, of Stockholm, one of the most eminent chemists of the age, with a request that he would favour me with an analysis. Some unavoidable de- lay was experienced in forwarding the bottle ; and no returns have yet been received. It is hoped, howe- ver, that they will arrive in time to be attached in an appendix to this volume.

The following results have been obtained from partial examinations and analyses of the gastric juice or rather, in most instances, of the mixed fluids of the stomach.

Spallanzani, in 1793, after many experiments, de- clared the gastric juice to be entirely neutral, a sol- vent for alimentary matter, within and without the sto- mach— that it did not putrcfij at the ordinary tempe- rature of the stomach; but preserved animal matters from putrefaction, and dissolved them, with the aid of heat.

ScopoLi found in the gastric juice of the rook, wa- ter, gelatine, a saponaceous matter, muriate of am- monia and phosphate of lime. Carminiti, in 1795,found it,,in caMiivorous animals, L

{(2 PRELIMINARY

wait and bitter, and frequently acid when they li.id eaten, but not so when lasting.*

ViRiDET, Werner, Hunter and others, found the gastric juice acid.

MM. Marquart and Vauquelin found albumen and free phosphoric acid in it.

TiEDEMANN and Gmelin found it to contain, on analysis, muriatic and acetic acid ; mucus ; very lit- tle or no albumen ; salivary matter ; osmazome ; mu- riate and sulphate of soda. In the ashes, carbonate, phosphate and sulphate of lime, and chloride of calcium. Principally from carnivorous animals.

Leuret and Lassaigne, in a hundred parts, found, water, ninety-eight, lactic acid, muriate of ammonia, muriate of soda, animal matter soluble in water, mu- cus, and phosphate of lime, two parts.

MoNTEGRE, (1812) who could vomit at tvill,l and who analyzed the fluid so obtained, declared it not to be acid — not a solvent — not slow to putrefy — so much like saliva, that he regards it sahva swallowed. - Prout, 1824, declares the gastric juice to be really acid — does not contain an organic acid, but free, hy- drochloric, or muriatic acid.

These opinions are certainly discordant. Tiie majority of evidence, however, is in favour of the ex- istence of pretty active chemical agents in the gas- tric fluids — perhaps not sufficient, m comparison with

* Probably because the fluid found in the stomach when fast- ing, was not gastric juice.

J See remarks near the close of this section on Montegre's ex- periments. *

OBSERVATIONS.

83

the ordinary operations of chemistry, to account for the digestion, or solution of ahment.

The discrepance of results in the reports of those who have had opportunities of examining the process of, and have made experiments on, artificial digestion, by the gastric juice, as well as in the chemical exami- nation of this fluid, has been owing more to the diffi- culty of obtaining it pure, in sufficient quantity, and under proper circumstances, than to any real differ- ence in its effects. Under the circumstances in which the following experiments were made, I flatter my- self that these difficulties have been obviated ; and if the inferences are incorrect, the blame must be at- tached to the experimenter. He can only say, that the experiments were made in good faith, and with a view to elicit facts.

I think I am warranted, from the result of all the experiments, in saying, that the gastric juice, so far from being " inert as water," as some authors assert, is the most general solvent in nature, of alimentary matter — even the hardest bone cannot withstand its action. It is capable, even out of the stomach, of effect- ing perfect digestion, with the aid of due and uniform degrees of heat, (100° Fahrenheit,) and gentle agi- tation, as will be seen in the following experiments.

The fact that alimentary matter is transformed, in the stomach, into chyme, is now pretty generally con- ceded. The peculiar process by which the change is eflTected, has been, by many, considered a problem in physiology. Without pretending to explain the exact modus operandi of the gastric fluid, yet I am im- pelled by the weight of evidence, afforded by the ex-

84 PRELIMINARY

perimcnts, deductions and opinions of the ablest phy- siologists, but more by direct experiment, to con- clude that the change cfiected by it on ahment is jmrcly chemical We must, I think, regard this fluid as a chemical agent, and its operation as a chemical action. It is certainly every way analogous to it ; and I can see no more objection to accounting for the change effected on the food, on the supposition of a chemical process, than I do in accounting for the various and diversified modifications of matter, which arc operated on in the same way. The decay oftlie dead body is a chemical operation, separating it into its elementary principles — and why not the .solution of aliment in the stomach, and its ultimate assimilation into fibrine, gelatine and albumen } Mat- ter, in a natural sense, is indestructible. It may be differently combined ; and these combinations are chemical changes. It is well known that all organ- ic bodies arc composed of very few simple principles, or substances, modified by excess or diminution of some of their constituents.

The gastric juice appears to be secreted from numberless vessels, distinct and separate from the mucous follicles. These vessels, when examined with a microscope, appear in the shape of small lu- cid points, or very fine papilla?, situated in the in- terstices of the follicles. They discharge their fluid only when solicited to do so, by the presence of ali- ment, or by mechanical irritation.

Pure gastric juice, when taken directly out of the stomach of a healthy adult, unmixed with any other fluid, save a portion of the mucus of the stomach'

OBSERVATIONS 85

with which it is most commonly, and perhaps always combined, is a clear, transparent fluid ; inodorous ; a little saltish ; and very perceptibly acid. Its taste, when applied to the tongue, is similar to thin mucil- aginous water, slightly acidulated with muriatic acid. It is readily diffusible in water, wine or spi- rits ; slightly efibrvesces with alkalis ; and is an ef- fectual solvent of the materia alimcntaria. It possess- es the property of coagulating albumen, in an emi- nent degree ; is powerfully antiseptic, checking the putrefaction of meat ; and effectually restorative of healthy action, when applied to old, foetid sores, and foul, ulcerating surfaces.

Saliva and mucus are sometimes abundantly mix- ed with the gastric juice. The mucus may be sepa- rated, by filtering the mixture through fine linen or mushn cambric. The gastric juice, and part of the saliva will pass through, while the mucus, and spu- mous or frothy part of the saliva, remains on the fil- ter. When not separated by the filter, the mucus ■gives a ropiness to the fluid, that docs not belong to the gastric juice, and soon falls to the bottom, in loose, white floccuh. Sahva imparts to the gastric juice, an azure tinge, and frothy appearance ; and, when in large proportion, renders it foetid in a few days ; whereas the pure gastric juice will keep for many months, without becoming foetid.

The gastric juice does not accumulate in the ca- vity of the stomach, until alimentary matter be re- ceived, and excite its vessels to discharge their con- tents, for the immediate purpose of digestion. It then begins to exude from its proper vessels, and in-

86 PRELIMINARY

creases in proportion to the quantity of aliment na- iurally required, and received. A definite proportion of aliment, only, can be perfectly digested in a given quantity of the fluid. From experiments on artificial digestion, it appears that the proportion of juice to the ingestaj, is greater than is generally supposed. Its action on food is indicative of its chemical cha- racter. Like other chemical agents, it decomposes, or dissolves, and combines with, a fixed and definite quantity of matter, when its action ceases. When the juice becomes saturated, it refuses to dissolve more ; and, if an excess of food have been taken, the residue remains in the stomach, or passes into the bowels, in a crude state, and frequently becomes a source of nervous irritation, pain and disease, for a long time ; or until the vis medicatrix naturm restores the vessels of this viscus to their natural and healthy actions — either with or without the aid of medicine. Such are the appearance and properties of the gastric juice ; though it is not always to be obtained pure. It varies with the changing condition of the stomach. These variations, however, depend upon the admixture of other fluids, such as saliva, water, mucus, and sometimes bile, and, perhaps, pancreatic juice. The special solvent itself— the gastric juice — is, probably, invariably the same substance. De- rangement of the digestive organs, slight febrile ex- citement, fright, or any sudden aflfection of the pas- sions, cause material alterations in its appearance. Ovorburthening the stomach produces acidity and rancidity in this organ, and retards the solvent action of the gastric juice. General febrile irritation seems

OBSERVATIONS.

87

entirely to suspend its secretion into the gastric ca- vity; and renders the villous coat dry, red and irri- table. Under such circumstances, it will not re- spond to the call of alimentary stimulus. Fear and anger check its secretion, also : — the latter causes an influx of bile into the stomach, which impairs its sol- vent properties.

V/hen food is received into the stomach, the gas- tric vessels are excited by its stimulus to discharge their contents, when chymification commences. It has been a favourite opinion of authors, that food, af- ter it has been received into the stomach, should " remain there a short period before it undergoes any change j"* the common estimate is one hour. But this is an erroneous conclusion, arising from in- accuracy of observation. Why should it remain there, unchanged } It has been received into the or- gan which is to effect an important change upon it — the gastric juice is ready to commence its work of solution soon after the first mouthful is swallowed ; and, certainly, if we admit that the gastric juice per- forms the office of a chemical agent, which most physiologists allow, it is contrary to all our notions of chemical action, to allow it one moment to rest. It must commence its operation immediately. That it does so, is distinctly manifested by close observa- tion of its action on food, in the healthy stomach.

But Paris is not alone in this opinion. It appears to have been a favourite doctrine; and has been regu- larly handed down, from one physiologist to another, as a sort of heir loom to the profession. The suc-

* Paris On Diet, p. 39.

88

PRELIMINARY

cessors in the physiological sciences seem to have been compelled to receive it with the legacy of their predecessors, without any doubt of its legitimacy ; when, with a little rational examination of the sub- ject, it would have been found a fair subject of rejec- tion. It will be seen, by the following experiments, that it has not the slightest foundation in truth ; and to them I refer the reader.

It has been said, that when one meal follows an- other in quick succession — or, in other words, when a subsequent meal is taken before the previous one is digested — that it some how disturbs the process of digestion. This is generally true ; and it allows of a definite solution. It is because more is received into the stomach, in the aggregate, than the gastric juice can dissolve. And this disturbance will result, as well when too much food has been taken at once, as when too much has been received in rapid succession. But if the quantity be moderate, no ill eflfect will ensue. Many children are in the habit of eating as often as once an hour through the day, in small quantities, without experiencing any bad consequences. Cooks are, also, accustomed to the practice of constantly tasting of the various articles of food which they are preparing for the table ; and yet I am not aware that they suffer any inconvenience from the habit. From these, and other facts, as well as from direct experi- ment, I think it is perfectly apparent that digestion must progress as well before as after the expiration of an hour. If, as has been suggested, the ingestion of food, in addition to the delay to itself, retards or stops the chymification of that vvliich hud been pre-

OBSERVATIONS.

8d

Viously received, aliment, as it relates to those chil- dren who eat hourly, would be constantly accumu- lating ; and there would remain in the stomach at night the whole quantity taken through the day : a supposition not to be credited, even by those dis- posed to make the most of a favourite opinion or doctrine.

Doctor Wilson Philip, in his Treatise on Indiges- tion," says, " the layer of food lying next to the sur*- face of the stomach, is first digested, and in propor- tion as this undergoes the proper change, and is moved by the muscular action of the stomach, that next in turn succeeds, to undergo the same change." That chvmification commences on the surface of tho food, I have no doubt ; but I apprehend this to be the case as it respects each individual portion, and not the whole mass. I have frequently taken out por- tions from the stomach, a few minutes after they had been received into that organ, when they appeared to have received a full supply of gastric juice for perfect digestion, when submitted to the artificial mode. When a due and moderate supply of food has been received, it is probable that the whole quan- tity of gastric juice for its complete solution, is se- creted, and mixed with it, in a short time. When an unusually full meal has been eaten, the necessary quantity for its complete solution, is not so readily supphed. If a tenacious mass of food be used, the external portion of the whole quantity is first acted on, digested, and succeeding portions presented, kc. There is no ground for the opinion inferred, that the

gastric juice never leaves the parietes of the sto- M

90 PRELIMINARY

mach, except as it chymifics food. It is a thin fluids and is governed by the same laws that other thin flu- ids are. From numerous examinations of the sto- mach, I feel warranted in saying, at least in the hu- man subject, that there is a perfect admixture of gastric juice and food — that the particles of food are constantly changing their relations with each other — and that they are mixed with a quantity of fluid, the gastric juice, liquids that have been taken during the meal, and (as there has generally been observed a large proportion of fluid, even after a dry and solid meal,) I have been led to suspect a synthetic forma- tion of water, from its elements. This mixture is perfectly heterogeneous at first, and is kept in con- stant agitation, by the churning motions of the sto- mach. If the contents of the stomach be taken out in from thirty minutes to an hour after eating, it will be found to be composed of perfectly formed chyme and particles of food, intimately mixed and blended ; sometimes in larger and sometimes in smaller pro- portions, according to the vigorous or enfeebled state of the digestive organs, or the quantity or quality of ahment taken. Most commonly, if the meal have been moderate, the process of digestion will continue in the portion taken out, when placed on the bath at a proper temperature, and the motions of the sto- mach imitated.

From the circumstance that the introduction of sponge, tubes, pebbles, &c. by Spallanzani and oth- ers, excited the discharge of the gastric juice, and from the fact that the gum-clastic tube, in my experi- ments, produced the same effect, when the stomach

OBSERVATIONS.

91

was empty and healthy, I infer, that the first eftecl of aUment on the stomach, is one oi irritation of the gastric papilL-e ; thus exciting the discharge of the gastric juice, and stimulating the muscular fibres of the stomach. The vermicular motions, being excited by mechanical irritation, not only carry the ingcstai into all parts of the stomach, and diffuse its mechani- cal influence throughout the whole inner surface of this organ ; but, by this means, they uniformly mix the ahment with the gastric juice, which is constant- ly being secreted, in proportion to the quantity of food received into the stomach, (unless that be too muchfor the wants of the economy,) until chymifica- tion be completed. Some stimulus seems to be ne- cessary to continue the motions of the stomach, after chymification is accomplished, in order to effect its complete discharge into the lower bowels. And it appears highly probable that the compound fluid of gastric juice and aliment, or chyme, by its acquired acid properties, affords this stimulus, and propagates the contractile motions of this organ, even after the mechanical irritation of the crude food ceases. This fluid acquires new chemical properties, becomes more acid and stimulating, as chymification advan- ces, until it is completed. When it is all transferred to the duodenum, the motions of the stomach cease. From a number of experiments on rabbits, by Doc tor Wilson- PHiLip,t with the view of ascertaining the process of digestion, this gentleman has brought his mind to the conclusion, that when food has been ta- ken at different times, " the new is never mixed with the

t On Digestion

91 PRELIMINART

old food." With every feeling of respect for so valu- able and indefatigable a contributor to physiological science, I must beg leave, however, to dissent from this opinion. In many of his experiments, the rabbits were killed soon after the introduction of a fresh quantity of food, and, generally, of a very different kind. The result was, that it was found separate from the old food, which was in an advanced stage of digestion. It was in the centre of the old food, and surrounded by it. This is precisely where a new bolus would be received, and retain its shape and consisten?c, in some measure, until disturbed, and broken u , by the motions of the stomach. By al- lowing sufficient time for the action of this organ, it is probable that the line of separation would not have been perceived. Indeed the Doctor concedes that when the second quantity of food was of the same kind as the first, and the rabbit had been left to live for some time, the line of separation was very indis- tinct. It appears that he fed rabbits on oats, and af- tcf ipaking them fast for sixteen or seventeen hours, ho fed them as much cabbage as they chose to eat, " and killed them at different periods, from one to eight hours after they had eaten it;" when the line of sepa- ration between the new food and that which had been eaten from eighteen to twenty-five hours before, was, no doubt, qiiite distinct. I confess I know very little about the habits of these animals, as it respects their modes of digestion ; but I should be inclined to think that if the " line of separation" between the two por- tions of food were not sufficiently distinct, it was not for want of time. In n)an, one fifth of the time would

OBSERVATIONS.

9^

have been more than sufficient to have disposed of any reasonable quantity of food.

Comparative physiology, as well as comparative anatomy, is undoubtedly, very useful; but. at the same time, it will not do to make it of general appli- cation. The rabbit is a ruminating animal ; and is it not probable that the " new food," found in the " small curvature," if it be in fact retained there, is detained for the purpose of regurgitation and re-mas- tication, before it is digested.'' If the circumstance be true, and there be no deception in the case, I think this must be the design of the contrivance.

Arguments from analogy may be very plausible, and are certainly very allowable, when the subject presents no other mode ; but they are not conclu- sive. We cannot judge of the mode of digestion in the human stomach by that of animals, particularly the granivorous and ruminating animals. Carnivo- rous animals most resemble man in their digestive apparatus. One thing is certain, and it is capable of demonstration in the stomach of the subject of these experiments, that old and new food, if they are in the same state of comminution, are readily and speedily mixed in the stomach.

On the subject of exercise or repose, during the di- gestion of a meal, there has been some diversity of opinion. It has generally been conceded, however, that a state of repose is most favourable to chymifi- cation. It has been said that during the digestion of aliment, the energies of the system were centred on the stomach, and should not be withdrawn to any distant part ; that the stomach becomes a " centre of

94 PRELIMINARY

fluxion," &c. &c. I protest, again, against the use of terms wliicli have no definite meaning. I believe the benefits of science will be better subserved by adhering to facts, and the deductions of experiment, than by tlie propagation of hypotheses founded on uncertain data. From numerous trials, I am per- suaded that moderate exercise conduces considera- bly to healthy and rapid digestion. The discovery was the result of accident, and contrary to precon- ceived opinions. I account for it in the following way. Gentle exercise increases the circulation of the system, and the /cmpcra/wrc of the stomach. This increase of temperature is generally about one and a half degrees. Now, if the gastric juice be a sol- vent, its action is similar to other chemical solvents, and its rapidity is increased in proportion to the ele- vation of temperature. Of the reason, I leave others to judge. The efl'ect is certain. Severe and fa- tiguing exercise, on the contrary, retards digestion. Two reasons present themselves for this — the debili- ity which follows hard labour, of which the stomach partakes ; and the depressed temperature of the sys- tem, consequent upon perspiration, and evaporation from the surface.

Exercise, sufficient to produce moderate perspira- tion, increases the secretions from the gastric cavi- ty, and produces an accumulation of a limpid fluid within the stomach, slightly acid, and possessing the solvent properties of the gastric juice in an inferior degree. This is probably a mixed fluid, a small pro- portion of which is gastric juice.

OBSERVATIONS. 95

Bile is not essential to chymificatioii. It is sel- dom found in the stomach, except under peculiar circumstances. I have observed that when the use of fat or oily food has been persevered in for some time, there is generally the presence of bile in the gastric fluids. Whether this be a pathological phe- nomenon, induced by the peculiarly indigestible na- ture of oily food ; or whether it be a provision of na- ture, to assist the chymification of this particular kind of diet, I have not as yet satisfied myself. Oil is affected by the gastric juice with considerable dif- ficulty. The alkaline properties of the bile may ren- der it more susceptible of solution in this fluid, by altering its chemical character. Irritation of the pyloric extremity of the stomach with the end of the elastic tube, or the bulb of the thermometer, general- ly occasions a flow of bile into this organ. Exter- nal agitation, by kneading with the hand, on the right side, over the regions of the liver and pylorus, produces the same eflfect. It may be laid down as a general rule, however, subject to the exceptions above mentioned, that bile is not necessary to the chymification of food' in the stomach. Magendie says, " I beheve that, in certain morbid conditions, the bile is not introduced into this organ," ( the sto- mach ;) inferring, that in a healthy state, it is al- ways to be found there. There can hardly be a greater mistake. With the exceptions that I have mentioned, it is never found in the gastric cavity, in a state of health; and it is only in " certain morbid conditions" that it is found there.

96 PRELIMINARY

VVlicn bile is found with the gastric juice, the acid taste is diminished, and the flavour of the bile pre- vails, in proportion to the quantity in the mixture.

The resulting compound of digestion in the sto- mach, or chyme, has been described as " a homo- geneous, pultaceous, greyish substance, of a sweet- ish, insipid taste, slightly acid," &c. In its ho- motreneous appearance, it is invariable ; but not in its colour ; that partakes very slightly of the colour of the food eaten. It is always of a lightish or greyish colour ; varying in its shades and appearance, from that of cream, to a greyish, or dark coloured gruel: It is, also, more consistent at one time than at ano- ther; modified, in this respect, by the kind of diet used. This circumstance, however, does not affect its homogeneous character. A rich and consistent quantity is all alike, and of the same quality. A poorer and thinner portion is equally uniform in its appearance^ Chyme from butter, fat meats, oil, &Ci resembles rich cream. That from farinaceous and vegetable diet, has more the appearance of gruel. It is invariably distinctly acid.

The passage of chyme from the stomach is gradu- al. Portions of chyme, as they become formed, pass out, and are succeeded by other portions. In the early stages, the passage of the chyme into the duo- denum, is more slowly effected than in the later sta- ges. At first, it is more mixed with the undigested portions of aliment, and is probably separated with considerable difficulty, by the powers of the stomach. In the later stages, as the whole mass becomes more

OBSERVATIONS. ■ 9^

Vnore chymified, and fitted for the translation, the pro-' cess is more rapid ; and is accelerated by a pccuhar contraction of the stomach, a description of which will be found in the next section. It appears to bo a provision of nature, that the chyme, towards tho latter stages of its formation, should become more stimulating, and operate on the pyloric extremity of the stomach, so as to produce this peculiar contrac- tion.

After the elxpulsion of the last particles of chyme, the stomach becomes quiescent, and no more juice is secreted, until a fresh supply of food is presented for its action, or some other mechanical irritation is applied to its internal coat.

Water and alcohol are not affected by the gastric iuice. Fluids, of all kinds, are subject to the same exemption, unless they hold in solution or suspen- sion some animal or vegetable aliment. Fluids pass from the stomach very soon after they arc received, either by a,bsorption, or through the pylorus.

Since the general adoption of the theory of a spe-- cific, solvent fluid, others have been proposed.

M. MoNTEGRE, who, it is said, had the power of vomiting at pleasure, performed a scries of experi- ments on the fluids of the stomach, obtained in this way, which induced him to come to a different con- clusion on the subject of digestion. '• He conceives that what has been supposed to be the gastric juice^ is, in fact, nothing but saliva ; that it possesses no peculiar powers of acting on alimentary matter ; that the principal use of the gastric juice is to dilutd

'Mi PRELIMINART

the food ; and that the only action of the stomach consists in ' unc absorption vitale et elective,' in which the absorbent vessels, in consequence of their peculiar sensibility, take up certain parts of the food, and reject others."* A complete refutation of the conclusions drawn from the experiments of Monte- gre, will be found in the fact, which has been tested by more than two hundred examinations and experi- ments, made by me, on the gastric cavity, that there never exists free gastric juice in the stomach, unless excited by afiment, or other stimulants. The fluid obtained by Mo^'TEGRE was, in all probability, a mixture of saliva (which had been unconsciously swallowed) and the mucus of the stomach. Neither of these secretions are capable of digesting aliment; nor could the pecuhar products, generally obtained from the chemical analysis of the gastric juice, be found in them.

The hypotheses proposed by Professors Smith and Jackson, of this country, are modifications of Monte- gre's theory.

The former of these gentlemen supposes that di- gestion is performed " by the veins of the stomach, and by the liver.'''' He contends, " that the first step in the process of digestion is effected by capillary veins originating in the villi of the stomach, with absorb- ing extremities, and terminating in the great branch- es of the vena portfe ;"| that this action is continued through the small intestines; that the absorbing

* Note in Bostook's Physiology, vol. 2, p. 384

I Essay on Digestion, p. 63.

OBSERVATIONS 99

reins take up the nutrient principles of the food, and reject, as excrementitious, the innutritious part ; that these nutrient principles are mixed with the return- ing blood within the cavity of the abdomen, and are carried into the liver, where the final processes of animalization and conversion into blood are com- pleted.

Professor Jackson-, in a recent work, has proposed a new theory, or rather revived, in some mea- sure, the theory of maceration. His hypothesis, as nearly as can be collected from his work, is as fol- lows : — He supposes that digestion is performed by submitting food to the action of different fluids, each of which has "solvent powers for different princi- ples;"* that the nutrient principles exist already formed in food, and are released from principles that are not required for nutrition, by a species of solu- tion, or maceration. The different fluids, as saliva, mucus from the mouth, throat, stomach, intestines, the bile and pancreatic juice, are the solvents of the different innutritive principles, and separate them from nutriment. He attributes great importance to the action of the sahva ; thinks it exercises a " very energetic operation on the food," &c. and denies, al- together, the existence of a specific solvent fluid.

It is unfortunate for the interests of physiological science, that it generally falls to the lot of men of vivid imaginations, and great powers of mind, to become restive under the restraints of a tedious and routine mode of thinking, and to strike out into bold and ori-

* Principles of Medicine, founded on the Structure and Func- tions of the Animal Organism, p. 354.

100 PRELIMIN'ART

ginal hypotheses to elucidate the operations of na- ture, or to account for the phenomena that are con- stantly submitted to their inspection. The process of developing truth, by patient and persevering inves- tigation, experiment and research, is incompatible with their notions of unrestrained genius. The drudg- ery of science, they leave to humbler, and more un- pretending contributors. The flight of genius is, however, frequently erratic. The bold and original opinions of Brown, for a long time unsettled the practice of medicine ; and the later opinions of Mon- TEGRE and others, have had alike effect on the sister Bcience o*" physiology. It is, however, aright, which menof ge: ius possess, in common with others, to pro- pose hypotheses, and to support them with such ar- guments and deductions as they may have in their power to bring. Great caution and circumspection ought, however, to be observed. It is dangerous to unsettle long established truths ; for it is difficult to Jimit the extent of error. The gratification of a mor- bid desire to be distinguished as the propagator of .^evy principles in philosophy, or as the head of a new «ect, is not the only result to be expected from such heresies. New opinions or doctrines, whether true or false, will have admirers and followers, and will lead to practical results. And the errors of one man may lead thousands into the same vortex.

These, of course, are designed as general remarks ; and I have no wish to apply them, so far as bad mo- tives arc inferred, to the highly respectable gentle- men mentioned above. Honest objections, no doubt, ftro entertained against the doctrine of digestion by

OBSERVATIQNS. 101

the gastric juice. That they are so entertained by these gentlemen, I have no doubt. And I cheerful- ly concede to them the merit of great ingenuity, tal- ents and learning, in raising objections to the com- monly received hypothesis, and ability in maintaining their peculiar opinions. But we ought not to allow ourselves to be seduced by the ingenuity of argument or the blandishments of style. Truth, like beauty, when " unadorned, is adorned the most ;" and in prosecuting these experiments and inquiries, I believe I have been guided by its light. Facts are more per- suasive than arguments, however ingeniously made, and by their eloquence, I hope I have been able to plead for the support and maintenance of those doc- trines, which have had for their advocates such men as Sydenham, Hunter, Spallanzani, Richerand Ab- ERNETHY, Broussais, Philip, Paris Bostock, the Hci- dleburgh and Paris Professors, Dunglison, and a host of other luminaries in the science of physiology.

SECTION n

Of the Appearance op the Villous Coat, and Op THE Motions of the Stomach.

THE inner coat of the stomach, in its natural and healthy state, is of a light, or pale pink colour, vary- ing in its hues, according to its full or empty state- It is of a soft, or velvet-hke appearance, and is con- stantly covered with a very thin, transparent, viscid mucus, lining the whole interior of the organ.

Immediately beneath the mucous coat, and appa- rently incorporated with the villous membrane, ap- pear small, spheroidal, or oval shaped, glandular bo- dies, from which the mucous fluid appears to be se- creted.

By applying aliment, or other irritants, to the in, ternal coat of the stomach, and observing the effect through a magnifying glass, innumerable minute lu- cid points, and very fine nervous or vascular papillae, can be seen arising from the villous membrane, and protruding through the mucous coat, from which dis- tills a pure, limpid, colourless, slightly viscid fluid. This Jluid, thus excited, is invariably distinctly acid. The mucus of the stomach is less fluid, more viscid ot

104 PRELIMINART

albuminous, semi-opaque, sometimes a little saltisllf and does not possess the slightest character of acid- ity. On applying the tongue to the mucous coat of the stomach, in its empty, unirritatcd state, no acid taste can be perceived. When food, or other irri- tants, have been applied to the villous membrane, and the gastric papillas excited, the acid taste is im- mediately perceptible. These papilla3, 1 am convin-' ced, from observation, form a part of what is called by authors, the villi of the stomach. Other vessels, perhaps absorbing as well as secretory, compose the remainder. That some portion of the villi form the excretory ducts of the vessels, or glands, I have not the least doubt, from innumerable, ocular examina- tions of the process of secretion of gastric juice. The invariable eft'ect of applying aliment to the internals but exposed part of the gastric membrane, when in a healthy condition, has been the exudation of the sol- vent fluid, from the above mentioned papillae. — Though the apertures of these vessels could not be seen, even with the assistance of the best micros- copes that could be obtained ; yet the points from which the fluid issued was clearly indicated by the gradual appearance of innumerable, very fine, lucid specks, rising through the transparent mucous coat, and seeming to burst, and discharge themselves up- on the very points of the papillaj, diffusing a limpid, thin fluid over the whole interior gastric surface. This appearance is conspicuous only during alimen- tation, or chymification. These lucid points, I have no doubt, are the termination of the excretory ducts of the gastric vessels or glands, though the closest

OBSERVATIONS.

105

and most accurate observation may never be able to discern their distinct apertures.

The fluid, so discharged, is absorbed by the ah- ment in contact, or collects in small drops, and trickles down the sides of the stomach, to the more depend- ing parts, and there mingles with the food, or what- ever else may be contained in the gastric cavity. This fluid, the efficient cause of digestion — the true gastric juice of Spallanzani, I have no doubt — has generally been obtained, for experiment, by mechan* ical irritation of the internal coat of the stomach, produced by the introduction of a gum-elastic tube, through which it has been procured.

The gastric juice never appears to be accumulated in the cavity of the stomach while fasting ; and is seldom, if ever, discharged from its proper secern- ing vessels, except when excited by the natural stim- ulus of aliment, mechanical irritation of tubes, or other excitants. When aliment is received, the juice is given out in exact proportion to its require- ments for solution, except when more food has been taken than is necessary for the wants of the system.

When mechanical irritation by a non-digestible substance, as the elastic tube, stem of the thermom- eter, &c. has been used, the secretion is probably less than when the irritation has been produced by such .substances, as are readily dissolved in the gastric juice. Alimentary stimulus, when taken into the sto- mach, is diffused over the whole villous surface, and excites the gastric vessels, generally, to excrete their fluids copiously ; whereas the irritation of tubes, &c.

106 PRELIMINARY

is local, and produces only a partial excitement of the vessels, and a scanty flow of the gastric juice. Hence, the slowness in obtaining the clear fluid from the empty stomach, through the tube. I have never, on numerous trials, been able to obtain, at any one time, more than one and a half, or two ounces of this fluid, after the stomach had disposed of its alimenta- ry matters, however long the period of abstinence had been. The discharge of this small quantity has generally been excited by the introduction of the tube. Ten, fifteen, or more minutes, Avere necessary to collect even this small quantity. Whenever fluid was obtained in larger quantity, as was sometimes the case, it invariably contained more than the usual quantity of mucus.

On viewing the interior of the stomach, the pecul- iar formation of the inner coats are distinctly exhi- bited. When empty, the rugre appear irregularly folded upon each other, almost in a quiescent state, of a pale pink colour, with the surface merely lubri- cated with mucus. On the application of aliment, the action of the vessels is increased ; the colour brightened ; and the vermicular motions excited. The small gastric papillne begin to discharge a clear, trans- parent fluid, (the alimentary solvent,) which contin- ues abundantly to accumulate, as aliment is received for digestion.

If the mucous covering of the villous coat be wiped oft', with a sponge or handkerchief, during the period of chymification, the membrane appears roughish, of a deep pink colour at first ; but in a few seconds, the follicles and fine papillae jjegin to pour out their

OBSERVATIONS.

lor

respective fluids, which, being diffused over the parts abraded of mucus, restore to them their pecul- iar soft and velvet-hkc coat, and pale pinli colour, corresponding with the undisturbed portions of the membrane ; and the gastric juice goes on accumu- lating, and trickles down the sides of the stomach again.

If the membrane be wiped off when the stomach is empty, or during the period of fasting, a similar roughness, and deepened colour appear, though in a less degree ; and the mucous exudation is more slowly restored. The follicles appear to swell more gradually. The fluids do not accumulate in quantity sufficient to trickle down, as during the time ofchy- mification. The mucous coat only, appears to be restored.

The foregoing, I beheve to be the natural appear- ances of the internal coat of the stomach, in a healthy condition of the system.

In disease, or partial derangement of the healthy function, this membrane presents various, and essen- tially different appearances.

In febrile diathesis, or predisposition, from whate- ver cause — obstructed perspiration, undue excite- ment by stimulating liquors, overloading the stomach with food — fear, anger, or whatever depresses or dis- turbs tiie nervous system — tl;e villous coat becomes sometimes red and dry, at other times, pale and moist, and loses its smooth and healthy appearance ; the secretions become vitiated, greatly diminished, or entirely suppressed; the mucous coat scarcely perceptible ; the follicles flat and flaccid, with secre^

108

PREMMINARV

tions insufficient to protect the vascular and nervous papillcB from irritation.

There are sometimes found, on the internal coat of the stomach, eruptions, or deep red pimples ; not numerous, but distributed, here and there, upon the villous membrane, rising above the surface of the mu- cous coat. These are at first sharp pointed and red ; but frequently become filled with white purulent mat- ter. At other times, irregular, circumscribed, red patches, varying in size or extent, from half an inch to an inch and a half in circumference, are found on the internal coat. These appear to be the effect of congestion in the minute blood vessels of the sto- mach. There are, also, seen at times, small aphthous crusts, in connection with these red patches. Abra- sions of the lining membrane, like the rolling up of the mucous coat into small shreds or strings, leaving the papilla) bare, for an indefinite space, is not an uncommon appearance.

These diseased appearances, when very slight, do not always affect, essentially, the gastric apparatus. When considerable, and, particularly, when there are corresponding symptoms of disease, as dryness of the mouth, thirst, accelerated pulse, &c. no o-as- tric juice can be extracted, not even on the applica- tion of alimentary stimulus. Drinks received, aro immediately absorbed, or otherwise disposed of; none remaining in the stomach ten minutes after be- ing swallowed. Food, taken in this condition of the stomach, remains undigested for twenty-four or forty- eight hours, or more, increasing the derangement of

OBSERVATIONS. 105)

the whole ahmentary canal, and aggravating the ge- neral symptoms of disease.

After excessive eating or drinking, chymification is retarded ; and, although the appetite be not al- ways impaired at first, the fluids become acrid and sharp, excoriating the edges of the aperture; and al- most invariably produce aphthous patches, and the other indications of a diseased state of the internal membrane, mentioned above. Vitiated bile is also found in the stomach under these circumstances ; and floccuU of mucus are much more abundant than in health.

Whenever this morbid condition of the stomach occurs, with the usual accompanying symptoms of disease, there is generally a corresponding appear- ance of the tongue. When a healthy state of the stomach is restored, the tongue invariably becomes clear.

Motions of the Stomach. — With the anatomy of this organ, I have, at present, nothing to do. It does not come within the limits which I have prescribed to myself. Its motions, as comprising a part of the process of digestion, I have endeavoured to observe as accurately as practicable, and I give the result.

The human stomach is furnished with muscular fasciculi, so arranged as to shorten its diameter in every direction. By, the alternate contraction and relaxation of these bands, a great variety of motion is induced on this organ, sometimes transversely, and at other times longitudinally. These alternate con- tractions and relaxations, when affecting the trans-i

110 PRELIMINART

verse diameter, produce what are called vermicular or peristaltic motions. The effect of the contraction of the longitudinal fibres, is to approximate the sple- nic and pyloric extremities. When they all act to- gether, the effect is to lessen the cavity of the sto- mach, and to press upon the contained aliment, if there be any in the stomach. These motions not only produce a constant disturbance, or churning of the contents of this organ, but they compel them, at the same time, to revolve around the interior, from point to point, and from one extremity to the other. In addition to these motions, there is a constant agi- tation of the stomach, produced by the respiratory muscles.

These contractions and relaxations of the muscu- lar fasciculi, do not observe any very exact mode. Their motions are modified by various circumstan- ces, such as the stimulant or non-stimulant property of the ingestEE, the healthy or unhealthy state of the internal coat of the stomach ; by exercise, and by re- pose, &c. &c.

The ordinary course and direction of the revolu- tions of the food, are first, after passing the ccsopha- geal ring, from right to left, along the small arch ; thence, through the large curvature, from left to right. The bolus, as it enters the cardia, turns to the left ; passes the aperture ; descends into the splenic extremity ; and follows the great curvature towards the pyloric end. It then returns, in the course of the smaller curvature, makes its appearance aorain at the aperture, in its descent into the great curvaturen to perform similar revolutions.

OBSERTATIONS. Ill

Such I have ascertained to be the revolutions of the contents of the stomach, from being able to iden- tify particular portions of food, and from the fact, that the bulb of the thermometer, which has been frequently introduced during chymification, invaria- bly indicates the same movements. These revolu- tions are completed in from one to three minutes. They are probably induced, in a great measure, by the circular or transverse muscles of the stomach, as indicated by the spiral motion of the stem of the ther- mometer, both in descending to the pyloric portion, and ascending to the splenic.t These motions are slower at first than after chymification has consider- ably advanced.

While these revolutions of the contents of the stomach are progressing, the trituration or agitation is also going on. There is a perfect admixture of the whole ingestae, during the period of alimentation and chymification. There is nothing of the distinct lines of separation between old and new food, and peculiar central or peripheral situation of crude, as distinguished from chymified aliment, said to have been observed by Philip, Magendie and others, in their experiments on dogs and rabbits, to be seen in the human stomach ; at least in that of the subject of these experiments. The whole contents of the sto- mach, until chymification be nearly complete, exhi- bit a heterogeneous mass of solids and fluids ; hard

t The terms " descending" and " ascending," are used here, as well as in many other places, relatively ; because the examina- tions were generally made while the man was lying on his right side.

112 PRELIMINART

and soft I coarse and fine; crude and chymifled ; all intimately mixed, and circulating promiscuously through the gastric cavity, like the mixed contents of a closed vessel, gently agitated, or turned in the hand.

If a mouthful of some tenacious food be swallow- ed, after digestion is considerably advanced, it will be seen passing tlie opening, to tiie great curvature ; and in the course of about one and a half or two mi- nutes, it will reappear, with the general circulating contents, more or less broken to pieces, or divided into smaller pieces ; and very soon loses its identity. This agitating motion has the effect, and is undoubt- edly designed, to break up the bolus, as well as to separate the external and chymified portion of the particles of food, and allow the undigested portions to come in contact with the gastric juice, their pro- per solvent. If the motions were simply revolution- ary, the central portions would retain their situation,, until the outer, or chymified part, had passed into the duodenum, in successive parcels : which, it is evident, would very much retard the process of di- gestion.

As the food becomes more and more changed from its crude to its chymified state, the acidity of the gastric fluids is considerably increased ; more so in vegetable than animal diet ; and the general con- tractile force of the nmscles of the stomach is aug- mented in every direction; giving the contained fluids an impulse towards the pylorus.

It is probable, that from the very commencement of chymification — from the time that food is received

OBSERVATIONS. 113

Btomach — until that organ becomes empty, portions of chyme are constantly passing into the duodenum, through the pyloric orifice, as the mass is presented at each successive revolution. I infer this, from the fact that the volume is constantly decreasing. This decrease of volume, however, is slow at first ; but is rapidly accelerated towards the conclusion of diges- tion, when the whole mass becomes more or less chymified. This accelerated expulsion appears to be effected by a peculiar action of the transverse muscles, or rather of the transverse band^ as descri- bed by Spallanzani, Haller, Cooper, Sir E. Home, and others, in their experiments on animals. This band is situated near the commencement of the more Gonically shaped part of the pyloric extremity, three or four inches from the smaller end. In attempting to pass a long glass thermometer tube, through the aperture, into the pyloric portion of the stomach, du- ring the latter stages of digestion, a forcible contrac- tion is first perceived at this point, and the bulb is stopped. In a short time, there is a gentle relaxation, when the bulb passes without difficulty, and appears to be drawn, quite forcibly, for three or four inches, towards the pyloric end, It is then released, and forced back, or suffered to rise again ; at the same time, giving to the tube a circular, or rather spiral motion, and frequently revolving it completely over. These motions are distinctly indicated, and strongly felt, in holding the end of the tube between the thumb and finger ; and it requires a pretty forcible grasp to prevent it from slipping from the hand, and being drawn suddenly down to the pyloric extremity. ■

114 l-KELIMINARV

When the tube h left to its own direction, at these periods of contraction, it is drawn in, nearly its whole length, to the depth often inches : and when drawn back, requires considerable force, and gives to the lingers the sensation of a strong suclion power, like drawing the piston from an exhausted tube. This ceases as soon as the relaxation occurs, and the tube rises again, of its own accord, three or four inches, when the bulb seems to be obstructed from rising further ; but if pulled up an inch or two, through the stricture, it moves treely in all directions in the cardiac portions, and mostly inclines to the splenic extremity, though not disposed to make its exit at the aperture.

Above the contracting band, and towards the sple- nic portion of the stomach, the suction or grasping motion is not perceptible ; but when the bulb is push- ed down to this point, it is distinctly felt to be grasp- ed, and confined in its movements.

These pecuhar motions and contractions continue until the stomach is perfectly empty, and not a par- ticle of food or chyme remains ; when all becomes quiescent again.

If the bulb of the thermometer be suffered to be drawn down to the pyloric extremity, and detained there for a short time, or if the experiment be repeat- ed too frequently, it causes severe distress, and a sensation like cramp, or spasm, which ceases on withdrawing the tube ; but leaves a sense of sore- ness and tenderness at the pit of the stomach.

These peculiar contractions and relaxations, men- tioned above, succeed each other, at irregular inter-

OBSERVATIONS.

llfj

vals, of froinr two to four or five minutes. Simulta- neously with ;the contractions, there is a general shortening of the fibres of the stomach. This organ contracts upon itself in every direction ; and its con- tents are compressed with much force. The valvu- lar portion of the stomach is firmly thrust into the a- perture ; closing the orifice ; preventing the egress of aliment ; and obstructing the view of the interior. During the intervals of relaxation, the ruga) perform their vermicular actions, the undulatory motions of the fluids continue, and the alimentary and chymous mass appear, revolving as before, promiscuously mixed, through the splenic and cardiac portions.

All these facts, taken together, will, I think, ration- ally admit of the following explanation. The longi- tudinal muscles of the whole stomach, with the assist- ance of the transverse ones of the splenic and cen- tral portions, carry the contents into the pyloric ex- tremity. The circular or transverse muscles eon- tract progressively, from left to right. When the impulse arrives at the transverse band, this is excited to a more forcible contraction, and, closing upon the aHmentary matter and fluids, contained in the pylo- ric end, prevents their regurgitation. The muscles of the pyloric end, now contracting upon the contents detained there, separate and expel some portion of the chyme. It appears that the crude food ex- cites the contractile power of the pylorus, so as to prevent its passage into the duodenum, while the thinner, chymified portion is pressed through the valve, into the intestine. After the contractile im- pulse is carried to the pyloric extremity, the circu-

1 1 6 PRELIMINART

lar band, and all the transverse muscles^ become re- laxed, and a contraction commences in a reversed di- rection, from right to left, and carries the contents a- gain to the splenic extremity, to midergo similar re- volutions.

It would 'appear, then, that the discharge of the chyme from the stomach, is effected by mechanic- al impulse. But, I confess, I do not like to give an opinion. I state the circumstances as they have oc- curred. The idea of mechanical force, I admit, is liable to objection ; but, perhaps, not more so than that of the selecting power of the pylorus. Whatever bias I may have in favour of the former method, has been forced upon me by the deductions of experiment and observation.

SECTION VII.

Of Chymification, and Uses of the Bile and Pancreatic Juice.

AS food becomes chymified by the gastric juice, the contractile motions of the stomach send it into the duodenum, to receive further changes, preparato- ry to its assimilation to the circulating fluids of the system, by the lacteal absorbents. It is at first slowly received into this organ from the stomach ; but during the later stages of chymification, its trans- mission becomes more accelerated. The duodenum is so constituted, that the passage of the chyme through it, is considerably retarded ; and, hence, in some pathological conditions of the system, the pressure on that organ from repletion, is considera- ble; and frequently produces great pain and dis- tress.

The vermicular motions of this and the other in- testines, are propagated from the stomach, and are continued, after this organ has discharged all its con- tents, by the contained fluids, until the whole be- comes assimilated. They are more or less rapid, varying at different sections of the canal ; of which

118

PRELIMINARY

it is not necessary to particularize. These motions are excited by the stimulus of the chyme, and occur at intervals, on the introduction of each quantity passed through the pylorus.

The chymous mass is not changed until it arrives at, or passes the mouth of the ductus cholodochus, when the liver and pancreas are excited to discharge their respective fluids. These mix vi^ith the chyme, and produce an essential alteration in its sensible and chemical properties. At this point, tlie lacteal absorbents commence.

That the change from a chymous to a chylous stage is effected by the operation of the bile and pancreat- ic juice, there can be no doubt. Of the nature of this change, there is some diversity of opinion. — Chyle is generally described as " a white, opaque substance, considerably resembling cream in its as- pect and physical properties ;"* though it is said to vary shghtly, according to the kind of aliment which had been used. It is my impression, however, that pure chyle, taken from the lacteals of a healthy sub- ject, and produced by natural food, is invariably the same substance in the same individual. Changes that have been observed, must be reckoned as the ef- fect of a pathological state of the system, or the ab- sorption of a non-digesting substance. Medicines and other substances, which are not capable of di- gestion, are sometimes taken up by the lacteal ab- sorbents, and may produce an alteration in the phy- sical and chemical properties of chyle. It is possible

* Bostock's Physiology, vol. 2d, p. 392. s

oBsfi^VATlONS. 119

that a small proportion of oil may escape the action of the digestive apparatus, be absorbed by the lac- teals, and produce the opaque, white colour, men- tioned by authors, as sometimes appearing. Coun- tenance is given to this suggestion, by the fact, that the more opaque coloured parts of chyle are found floating on the surface ; and that it is alwavs disco- vered after the ingestion of oily food. At other times, it is uniform in its colour and consistence, whatever colouring matter may have been contained in the food.

I wish to be understood to say, that every species of aliment produces the same fcVic/ of nutrient princi- ciples. With the view of attempting an investigation of this subject, as has been previously mentioned, I instituted some imperfect experiments and examina- tions. For the result, see Experiments, Second Se- ries, from 47th to 56th. By the addition of bile and dilute muriatic acid, and subsequently pancreatic juice, to chyme formed in the artificial way, as well as in the stomach, it separated into three distinct parts, a reddish brown sediment at the bottom, a whey coloured fluid in the centre, and a creamy pel- licle at the top. Each repetition of the experihient produced a similar result ; though not exadhj alike in all. The central portion, I suspect to be imperfect- ly formed chyle. The sediment, from its appearance, and the coarseness of its particles, 1 judge, is inca- pable of being acted on, or taken up, by the absorb- ents : the creamy or oily pelhcle is not only liable to the same objection, but is in too small proportion to the ingesta. The fluid part is fitted, by its fluidity.

120 PRELIMINARY

for the ready action of the absorbents ; and is, more- over, in sufficient quantity for the purposes of nutri- tion. The change of colour and consistence is, pro- bably, effected in tlie lacteal glands and vessels. The sediment and pellicle, I apprehend, arc both ex- crementitial. The " irregular filaments," attached to the valvuliE conniventes, mentioned by Magendie, and which he concluded to be imperfectly formed chyle, were, undoubtedly, portions of the creamy pel- hcle, found in the experiments referred to.

But what is the nature of the changes effected in the duodenum ? Aliment, after being introduced in • to the stomach, is dissolved in the gastric juice, and forms a new compound with this fluid. The con- stituent elements of food are various. When com- pounded with the gastric juice, they may, neverthe- less, be said to form a simple compound, or a gastrite of aliment. I am indifferent about terms ; and this will as well convey my meaning as any other. When this gastrite is introduced into the duodenum, and mixed with the hepatic and pancreatic fluids, are we not warranted, from all the facts that have been ob- served, in saying, that there is a general play of che- mical affinities in that organ, separating the nutrient principles, and forming various new compounds from the elements of each } The chymous mass changes its colour, and loses its acidity. There is a sensible extrication of gas, as observed by Magendie, and others,* In the stomach, oxigen is found mixed with a small proportion of hydrogen. In the intes-

* The escape of gas is generally observable in mixing these fiuitb with chyme, in my experiments.

OBSERVATIONS. tS^

tines, an increased proportion of hydrogen exists, with carbonic acid, nitrogen, (fee. ; but no oxygen. Does not the acid of the chyme unite with the alkahs of the bile, and form new compounds .'' And do not other equally important changes take place .'' This subject, I confess, is obscure, and perhaps will not admit of a very perfect investigation.

The constant agitation which is maintained in the intestines, preserves the chyle in a state of perfect admixture with the other fluids, until absorption has taken place. By standing at rest, the separation, mentioned above, is evident and perfect.

It has been supposed that the mucus of the intes- tines has some agency in the formation of chyle. But I am disposed to think, with Professor Dungli- soN, and others, that the use of the mucus is to lu- bricate the internal coat of the intestines, and, per- haps, to dilute their contents.

It has been suggested that digestion can be per- fected in the duodenum and lower bowels, when the food has not been submitted to the action of the sto- mach and its fluids. In two experiments by Magen- DiE, one failed, and the other was attended with par- tial success. Too much reliance ought not to be placed on experiments, that require such severe and cruel vivisections, as were resorted to in these cases. It is possible, as suggested by Dunglison, that the presence of crude aliment in the duodenum, may ex- cite the discharge of gastric juice in the stomach, its expulsion into the duodenum, and its consequent ac- tion on the food, before it is affected by the bile and pancreatic juice. Or, it may be that the upper part

122 PRELIMINART

of the duodenum is furnished with vessels, which se- crete a fluid similar to gastric juice,

Experiments have also been instituted with the view of ascertaining, whether chyle caa be formed without the admixture of the hepatic and pancreatic fluids, with various results. Brodie ascertained, by tying the ductus communis cholodochus in young cats, that the process of chyUfication was prevented, and that no chyle was found in the intestines, Ma- GENDiE, Leuret and Lassaigne, on tying this duct, discovered matter of " a rosy yellow colour," which aflforded, on analysis, the same constituents of chyle, although the animals, which were the subjects of the operation, had been hept some time without food. There is certainly an apparent discordance in these reports. But, it is possible, they may be explained, and reconciled. It is well known that the absorbents are active during a protracted fast, (as in these last experiments) and are constantly taking up the ceflu- lar substance, for the purpose of supplying the blood vessels with these broken up solids of the system. Emaciation is the effect of absorption. The lacteals, like other absorbents, have, undoubtedly, their ap- propriate stimulus ; but if that be withholden, they will feed on other substances, the cellular and other solid parts, within their reach. If such be the case it wiU account for the rosy coloured fluids found ii> the lacteals, by Magendie and others.

aZPSI^IKSHTS

OBSBRlTATIOlirS; fiCOb

HZPSRZnXEMTS, UC

FIRST SERIES.

'Experiment T.

Jugust 1, 1825. At 12 o'clock, M., I introduced through the perforation, into the stomach, the follow- ing articles of diet, suspended by a silk string, and fastened at proper distances, so as to pass in with- out pain — viz. : — a piece of high seasoned a la mode beef; a piece of raw, salted, fat pork ; a piece of raw, salted, lean beef ; a piece of boiled, salted beef ; a piece of stale bread ; and a bunch of raw, sliced cabbage ; each piece weighing about two drachms ; the lad continuing his usual employment about the house.

At 1 o'clock, P. M., withdrew and examined them — found the cabbage and bread about half digested r the pieces of meat unchanged. Returned them into the stomach.

At 2 o'clock, P. M., withdrew them again — found the cabbage, bread, pork, and boiled beef, all cleanly di- gested,t and gone from the string; the other pieces of

t These Experiments are inserted here, as they were original- ly taken down in my Note Book, with very little alteration of phraseology, and none of the sense. Subsequent experiments have sometimes convinced me of errors in former ones. When ttii has been the case, I have generally made the corrections in the way of remarks, or observations, as in this experiment.

126 fixFERIMENTS ANO

meat but very little 9.ffected, Returned tbem mta

the stomach again.

At 2 o'clock, P. M., examined again— found the a la mode 6ec/ partly digested: the raw beef^Nn.s slight- ly macerated on the surface, but its general texture was firm and entire. The smell and taste of the fluids of the stomach were slightly rancid; and the boy complained of some pain and uneasiness at the breast. Returned them again.

The lad complaining of considerable distress and uneasiness at the stomach, general debility and lassi- tude, with some pain in his head, I withdrew the string, and found the remaining portions of aliment nearly in the same condition as when last examined ; the fluid more rancid and sharp. The boy still com- plaining, I did not return them any more.

Jlugust 2. The distress at the stomach and pain in the head continuing, accompanied with costive- ness, a depressed pulse, dry skin, coated tongue, and numerous white spots, or pustules, resembling coa- gulated lymph, spread over the inner surface of the stomach, I thought it advisable to give medicine; and, accordingly, dropped into the stomach, through the aperture, half a dozen calomel pills, four or five grains each ; which, in about three hours, had a thorough cathartic effect, and removed all the fore- going symptoms, and the diseased appearance of the inner coat of the stomach. The effect of the medi- cine was the same as when administered in the usual way, by the mouth and oesophagus, except the nausea commonly occasioned by swallowing pills.

This experiment cannot be considered a fair test of the powers of the gastric juice. The cabbage, one of the articles which was, in this in- stance, most speedily dissolved, was cut into small, fibrous pieces, very thin, and necessarily exposed, on all its surfaces, to the action of the gastric juice.

OBSERVATIONS. 127

The stale bread was porous, and, of coarse, admit- ted the juice into all its interstices ; and probably fell from the string as soon as softened, and before it was completely dissolved. These circumstances will account for the more rapid disappearance of these substances, than of the pieces of meat, which were in entire solid pieces when put in. To account for the disappearance of the fat pork, it is only necessary to remark, that the fat of meat is always resolved in- to oil, by the warmth of the stomach, before it is di- gested. I have generally observed that when he has fed on fat meat or butter, the whole superior portion of the contents of the stomach, if examined a short time after eating, will be found covered with an oily pellicle. This fact may account for the disap* pearance of the pork from the string. I think, uj)- on the whole, and subsequent experiments have con- firmed the opinion, that fat meats are less easily di- gested than lean, when both have received the same advantages of comminution. Generally speaking, the looser the texture, and the more tender the fibre, of animal food, the easier it is of digestion.

This experiment is important, in a pathological point of view. It confirms the opinion, that undiges- ted portions of food in the stomach produce all the phenomena of fever ; and is calculated to warn us of the danger of all excesses, where that organ is concerned. It also admonishes us of the necessity of a perfect comminution of the articles of diet.

Experiment 2.

Jutr. 7. At 1 1 o'clock, A. M., after having kept the lad fa'sting, for seventeen hours, I introduced the glass

i^8

EXPKftlMENTS ANlJ

tube of a Thermometer (Fahrenheit's) through the perforation, into tiie stomach, nearly the whole length bf the stem, to ascertain the natural warmth of the etomach. In fifteen minutes, or less, the mercury rose to 100°, and there remained stationary. This I determined by marking the height of the mercury on the glass, with ink, as it stood in the stomach, and then withdrawing it, and placing it on the gaduated scale again.

I now introduced a gum-elastic (caoutchouc) tube, knd drew off one ounce of pure gastric liquor, unmix- ed with any other matter, except a small proportion of mucus, into a three ounce vial. I then took a solid piece oC boiled, recently salted beef, weighing three drachms, and put it into the liquor in the vial ; corked the vial tight, and placed it in a saucepan, filled with water, raised to the temperature of 100°, and kept at that point, on a nicely regulated sand bath. In forty tniniiles digestion had distinctly commenced over the Surface of the meat, infifty minutes the fluid had be- come quite opaque and cloudy ; the external texture began to separate and become loose. In sixty mi- nutes, chyme began to form.

At 1 o'clock, P. M., (digestion having progressed with the same regularity as in the last half hour,) the cellular texture seemed to be entirely destroyed, leaving the muscular fibres loose and unconnected, floating about in fine small shreds, very tender and soft;

At 3 o'clock, the muscular fibres had diminished one half, since last examination, at 1 o'clock.

At 5 o'clock, tliey were nearly all digested ; a few fibres only remaining.

At 7 o'clock, the muscular texture was completely broken down; and only a few of the small fibres floating in the fluid.

At 9 o'clock, every part of the meat was complete- ly digested.

The gastric juice, when taken from the stomachy

OBSERVATIONS. J^

tVas as clear and transparent as water. The mixture in the vial was now about the colour of whey. After standing at rest a few minutes, a fine sediment, of the colour of the meat, subsided to the bottom of the vial.

Experiment 3.

At the same time that I commenced the foregoing experiment, I suspended a piece of beef, exactly simi- lar to that in the vial, (Ex. 2d) into the stomach, through the aperture.

At 12 o'clock, M., withdrew it, and found it about as much affected by digestion as that in the vial ; there was httle or no difference in their appearance. Heturned it again.

At 1 o'clock, P. M., I drew out the string ; but the meat was all completely digested, and gone.

The effect of the gastric juice on the piece of meat, suspended in the stomach, was exactly similar to that in the vial, only more rapid after the first half hour, and sooner completed. Digestion commenced on, and was confined to, the surface entirely, in both, situations. Agitation accelerated the solution in the vial, by removing the coat that was digested on the surface; enveloping theremainder of thcmeatin the gastric fluid ; and giving this fluid access to the undigested portions.

Experiment 4.

Jug. 8. At 9 o'clock, A. M., I drew off an ounce and a half of gastric juice, into a three ounce vial ; sus- |)ended two pieces of boiled chicken, from the breast and back, into it, and placed it in the same situation and temperature as in the second experiment ; ob- serving the same regularity and minuteness.

Digestion commenced and progressed much the game, as in the second experiment, but rather slower ; the fowl appearing to be more difficult of digestion than the Jlesh. The texture of the chicken being clo-

I. '50 EXPERIMENTS AND

scr than that of the beef, the gastric juice appeared not to insinuate itself into the interstices of the mus- cular fibre, so readily as into the beef ; but operated entirely upon the outer surface, dissolvnig it as a piece of gum arabic is dissolved in the mouth, until the last particle was digested.

The colour of the fluid, after digesting the chick- en, was of a greyish white, and more resembled a milky fluid than whey, which was the colour of the chyme from the beef.

The contents of both vials, kept perfectly tight, remained free from any footer, acidity, or offensive •smell or taste, from the time of the experiments, (7tli and 8th August,) to the 6th of September ; at which time, that containing the solution oi boiled beef, became very ofiensive and putrid ; while that con- taining the chyme from the boiled chicken, was per- fectly bland and sweet. Both were kept in exactly similar situations.

It is, perhaps, unnecessary to make any comments on the result of the above experiments. Each one will make up his opinion from the facts. These de. monstrate, at least, that the stomach secretes a fluid which possesses solvent properties. The change in the solid substances is effected too rapidly to be accounted for on the principle of either maceration or putrefaction. I shall be able to show, in some of the following experiments, that ahment undergoes the same changes in the stomach, as is effected in the mode here adopted.

The young man, who was the subject of these ex- periments, left me about this time, (September, 1825) and went to Canada, the place of his former resi- dence. The experiments were consequently sus- pended,

ESPERZiaENTS, bLC

SECOND SERIES.

Fort Crawford, Upper Mississippi^ June 20th, 1829.

Alexis St. Martin having returned from Canada, after an absence of nearly four years, with his sto- mach in the same, or very similar condition, as when he left me in September, 182.5, I continued to prose- cute the gastric experiments, which were commenced before he left me.

With a view to ascertain the variations of tempe- rature, if any there were, in the interior of the sto mach, under different circumstances and conditions of the system, and vicissitudes of the atmosphere, I instituted the following experiments.

Experiment 1 .

Dec. 6, 1829. At 9 o'clock, A. M., I introduced the glass tube of a Thermometer (Fahrenheit's) through the artificial opening into the stomach, in a healthy and empty condition, nearly the whole Jejigth of the stem. In six or eight minutes, the mcr-

132

EXPERIMENTS A.\P

cury became stationary, at 94°. Weather cloudy, damp, and almost raining — ground wet, muddy and thawing. Wind S. and mild. Thermometer, in a North oxposure, 63°. Commenced raining at 11 o'- clock, A. M., and continued all day, with oppressive atmosphere.

Experiment 2.

Dec. 7. Introduced Thermometer at the same hour as yesterday — circumstances of stomach the same. Mercury at 96°. Weather cloudy — Atmos- phere damp— Wind N. W. and light— Th : 27°.

Experiment 3.

Dec. 6. Introduced Thermometer at 9 o'clock, A. M. — circumstances of stomach same as yester- day. Mercury stationary at 99°. Weather clear — Atmosphere dry — Wind S. W. and light — Th : 13°.

Experiment 4.

Dee. 9. Introduced Thermometer at 9 o'clock, A. M. — circumstances similar. Mercury stationary at 99°. Weather clear — Atmosphere dry — Wind W. jind light— Th: 10°.

Experiment 5.

Jan. 24, 1830. Introduced Thermometer at 3 o'- clock, P. M. Weather clear and cold — Th: 8° be- low o. — Wind N. W. and light — stomach empty, and coats healthy. Mercury stationary at 100°

Experiment 6.

Jan. 25. Introduced Thermometer at 8 o'clock, A. M. Weather clear — Wind S. W. and light — Th :' 2° — Stomach empty. Mercury stationary at 100°.

OBSERVATIONS. 133

At 10 o'clock, A. M., (one hour after eating a breakfast of pork and bread,) introduced Thermome- ter again. Mercury stationary at 100°, as at 9 o'- clock, before eating.

Experiment 7.

March 17. At 10 o'clock, A. M., introduced Ther- mometer. Weather rainy and foggy — Wind S. W. and light — Th: 38° — Stomach empty, having eaten nothing since 7 o'clock last evening. Mercury sta- tionary at 99°.

Experiment 8.

March 18. At 8 o'clock, A. M., introduced Ther- mometer. Mercury stationary at 100°. Weather clear— Wind N. W.— Th : 6°.

At 9 o'clock, breakfasted on meat, biscuit and but- ter, with coffee. Temperature of the stomach, im- mediately before eating, 100° : thirty minutes after finishing breakfast the temperature had risen to 102". Digestion rapidly advancing.

It appears, from the above experiments, that the variations of the atmosphere produce eifects upon the temperature of the stomach ; a dry atmosphere increasing, and a humid one diminishing it. What would be the effect of copious perspiration, in warm weather, on the temperature of the stomach ? Would that of the interior of this organ be lessened by eva- poration .'' I regret that sufficient experiments have not been made, fully to satisfy these inquiries. From one or two experiments, it would seem, that the heat of the stomach was increased during the active pe- riod of digestion. This, however, was probably ow- ing to exercise, immediately after eating, though not

134 EXPERIMENTS AND

particularly observed and noted at the time. Sub- sequent experiments have not shown this result. On the contrary, the temperature has been found to be the same, in its full and empty state.

The ordinary temperature of the healthy stomach, may be fairly estimated at 100°, Fahrenheit. Some allowance ought, probably, to be made, in these ex- periments, for imperfect instruments. It appears, from subsequent examinations, that there is probably some difference of temperature in difterent regions of the stomach, it being higher at the pyloric than at the splenic end. See subsequent experiments and observations.

To ascertain whether the Gastric Juice be accu- mulated in the stomach, during periods of fasting, or even from the immediate and direct ini3uence of hun- ger, I made the following experiments.

Experiment 9.

Dec. 5, 1829. At 8 o'clock, A. M., after twelve hours abstinence from either food or drinks, I intro- duced, at the perforation, a gum-elastic tube, and

drew off a drachm or two only of the gastric juice.

There was no accumulation in the stomach.

Experiment 10.

Dec. 12. At .3 o'clock, P. M., introduced tube- could procure two or three drachms only — this was secreted on the irritation of the tube. Stomach con- tained none in a free state.

OBSERVATIONS. 1 35

Experiment 11.

Dec. 14. At 10 o'clock, P. M., after eighteen hours fasting, introduced tube, and drew off one and a half ounces of gastric juice. It was clear, and al- most transparent ; tasted a little saltish and acid, when applied to the tongue, similar to thin mucilage of gum arabic, slightly acidulated with muriatic acid. There was no accumulation in the stomach when the tube was introduced.

Experiment 12.

March U, 1830. At 10 o'clock, A. M.— stomach empty — introduced tube ; but was unable to obtain any gastric juice. On the application of a few crumbs of bread to the inner surface of the stomach, the juice began slowly to accumulate, and flow through the tube. The crumbs of bread adhered to the mucous coat, soon became soft, and began to dissolve and digest. On viewing the villous mem- brane before applying the bread crumbs, the mucous coat and subjacent follicles only, could be ob- served ; but immediately afterivards, small, sharp pa- pilte, and minute lucid points, situated in the intersti- ces of, and less than, the mucous follicles, became visible ; from which exuded a clear, transparent li- quor. It then began to run through the tube.

Experiment 13.

March 18. At 6 o'clock, P. M., after fasting from 8 o'clock, A. M., introduced tube — obtained one and a half ounces gastric juice, after having kept up the UTitation, by moving the tube from point to point, for twelve or fifteen minutes. No accumulation of free juice in the stomach.

13G EXPERIMENTS AWP

Experiment 1 4 .

Jan.m, 1831. At 9 o'clock, A. M.— stomach emp ty — extracted one ounce gastric juice, slowly through" the tube, with the usual admixture of mucus. Intro- duced food, and it began directly to flow more free- ly through the tube.

Experiment 15.

Jan. 27. At 8 o'clock, A. M. — stomach empty — introduced elastic tube, and obtained one and a half drachms of gastric juice, by very slow distillation, j^pplied crumbs of bread to the villous coat, and the juice began immediately to flow freely through the tube.

Experiment 16.

March 6. At 8 o'clock, A. M., extracted two oun- ces gastric juice, and added it to two ounces of Ma- deira wine. No visible change was produced — no coagulaj formed. They united, like pure water and wine. Heat produced no other effect

Experiment 17.

March 7. At C o'clock P. M.— stomach empty- extracted one and a half ounces of juice, and mixed k with the same quantity of Jamaica spirits. Effect same as with wine.

Experiment 18.

March 8. At 8 o'clock, A. M.— stomach empty- extracted one and a half ounces of gastric juice.

Experiment 19.

March 12. At 9 o'clock, A. M.— stomach empty- extracted one and a half ounces of gastric juice. Put this in a bottle.

OBSERVATIONS. ISt

Experiment 20.

March 13. At 11 o'clock, A. M. — stomach empty —extracted two ounces of juice.

Experiment 21.

March 14. At 12 o'clock, M. — stomach cmpty^ extracted two ounces of juice.

Experiment 22.

March 15. At 4 o'clock P. M. — stomach empty — > extracted one and a half ounces gastric juice.

Experiment 23.

March 16. At 5 o'clock P. M., introduced tube — could obtain no clear gastric juice. A little acrid fluid and frothy mucus, only, could be extracted. Vil- lous membrane red and dry. St. Martin complained of some head ache, pain and distress about the scro- biculus cordis, lassitude and loss of appetite. Direct- ed him to take half an ounce of tincture of aloes and myrrh, at 9 o'clock, P. M. This moved Jiis bowels several times next morning. Little or no change was apparent in the appearance of the inner coat of the stomach ; if any, it was a little more moist, and a shade paler, after the operation of the tincture. Gas- tric juice could again be obtained, but in less than usual quantity.

It would seem, from the preceding cx'perimcnts, that the stomach contains no (rcistric juice, in a free state, when aliment is not present. Any digestible or irritating substance, when ai)plied to the internal coat, excites the action of the gastric vessels. Hence, I infer that the fluid, in these experiments, was inci- S

138 EXPERIMENTS AIND

ted to discharge itself by the irritation of the tube used in extracting it.

If, as is contended for by some, a part of the fluid be discharged into the stomach during a fast, I see no reason why nature should withhold the other part. If we may be allowed to argue, independent of more certain data, one great objection to the o- pinion that the stomach contains gastric juice, in a free state, when food is withholden from it, exists in the danger of its passing out through the pyloric ori- fice ; and thus depriving the succeeding meal of the benefit of its solvent action. It is probable that the pyloric orifice opposes no resistance to its egress ; but is obedient to its summons. In this way wc may account for its admitting chyme, which is an admix- ture, or rather, combination, of gastric juice and food, to obey the expulsive motions of the stomach, and pass out. They both appear to excite the pe- culiar contraction of the pyloric end of the stomach, mentioned in a former part of this work. Besides, there would be danger of the gastric juice beinir weakened, by the introduction of large quantities of water, or other fluids, in the intervals of eating, and thus lose its energy, and concentrated solvent pro- perties.

The last experiment has considerable pathologi- cal importance. In febrile diathesis, very little or no gastric juice is secreted. Hence, the importance of withholding food from the stomach in febrile com- plaints. It can afford no nourishment ; but is actual- ly a source of irritation to that organ, and, conse- quently, to the whole system. No solvent can be se-

OBSERVATION?:

139

creted under these circumstances ; and food is as insoluble in the stomach, as lead would be under or- dinary circumstances.

The following, and most of the subsequent experi- ments of this series, were instituted with the view of ascertaining the relative difference between natu- ral and artificial digestion ; to demonstrate the per- formance of digestion out of the stomach, by the gas- tric juice ; and, also, the continuation of the natural process, when taken out during the period of chymi- fieation.

Experiment 24.

Dec. 14, 1829. At 1 o'clock, P. M., I took one and a half ounces of gastric juiee, fresh from the gtomach, after eighteen hours fasting, into an open mouthed vial — put into it twelve drachms recently salted beef, (boiled) and placed it in a basin of water, on a sand bath, and kept it at about 100° (Fahrenheit.) with frequent, gentle agitation. Diges- tion commenced, in a short time, on the surface of the meat, and progressed in that manner uniformly for about six hours, when its solvent action seemed to cease. The meat was at this time, nearly half dissolved ; the texture of the central portion consir derably loosened and tender, resembling the same kind of aliment when ejected, partly digested, from the stomach, some hours after being swallowed, as frequently seen in eases of indigestion.

The vial, continuing in the same situation, its con- tents varied considerable in their'sensible quahties. In twenty-four hours, the digested "portion separated

140 EXPERIMENTS AND

into a reddish brown precipitate, and whey coloured fluid.

I now separated the undigested from the chymoua portion, by filtration, through thin mushn. When squeezed dry, it weighed five drachms, two scruples, and eight grains, which, deducted from the twelve drachms of meat put in at first, leaves six drachms and twelve grains, digested in twelve fluid-drachms of gastric juice.

This experiment was conducted with as much pre- cision and integrity of observation as possible, with the temperature of the digesting bath kept as near blood heat as was practicable to regulate and con- tinue artificial warmth — the Thermometer varying, during the time, from 90° to 100°.

In this experiment, it appears, that it took twelve drachms of gastric juice to digest six drachms and twelve grains of aliment. No certain rule can, how- ever, be given. Allowance must be made for the puri- ty of the fluid, or its admixture with mucus and other secretions; for it is altogether probable that there are great variations in it, in this respect, as well as in all the other secretions of the system. It is probable, also, that different kinds of diet require different pro- portions of gastric juice for their solution. That its action is similar to that of other chemical agents I have no doubt. A given quantity of the fluid acts on a definite proportion of aliment, when it becomes sat- urated, and is inadequate to produce any further ef- fect. There is always disturbance of the stomach when more food has been received than there is gas- tric juice to act upon it.

OBSERVATIONS, 141

Experiment 25.

Dec. 16. At 2 o'clock, P. M. — twenty minutes after having eaten an ordinary dinner of boiled, salted beef, bread, potatoes and turnips, and drank a gill only of pure water, I took from his stomach, through the ar- tificial opening, a gill of the contents, into an open mouthed vial. Digestion had evidently commenced, and was perceptibly progressing, at the time. This vial and contents were immediately placed in a basin of water, on the sand bath, at 90° or 100°, and con- tinued there for five hours.

The digestion of the contents continued to pro- gress, until all was completely chymified.

At 7 o'clock — five hours after eating his dinner — I took out a gill of pure chyme; no particles of undi- gested food appearing in the mixture.

Very little difference was perceptible between this last parcel and that in the vial, digesting on the bath. The stomach had digested a httle faster and more perfectly than the vial.

In this experiment, it seems, that a quantity of ali- ment, taken out of the stomach ttventy minutes after having been eaten, hfidasuflicient admixture of gas- tric juice to ensure its perfect digestion when placed on the bath. An ordinary moderate meal, taken in- to a healthy stomach, is sooner disposed of than most physiologists are aware of; and in this case, it is probable that a sufficient quantity of gastric juice had been secreted in twenty minutes, to digest the whole quantity of aliment in the stomach. When a larger quantity has been received, though the powers of the stomach may be suflicient, ultimately to dis- pose of it, it would undoubtedly be found that a por- tion taken from the stomach a few minutes after ha»

142 EXPERIMENTS AITD

ving been eaten, would not contain a sufficient quan- tity of gastric juice to digest it perfectly. It is possible that the portion presented at the perforation may be in a more advanced stage of digestion, than the rest of the mass, and consequently lighter, and float on the surface of the more solid portions of the food. In ordinary cases, such would be found to be the case ; but when much fat meat or oily food has been used, the oil always maintains an ascendency in the gastric cavity.

Experiment 26.

Jan. 11, 1830. At 3 o'clock, P. M., dined on bread and eight ounces of recently sailed, lean beef, four ounces of potatoes, and four ounces of turnips, boiled. Infifteen niinutes,took out a portion of the contents of the sto- mach. The meat made its appearance, in an incipient stage of digestion.

At 3 o'clock, 45 minutes, took out another portion. The meat and bread only appeared, in a still more advanced stage of digestion.

Tile texture of the meat was, at this time, broken into small shreds, soft and pulpy, and the fluid con- taining it had become more opaque, and quite gruel- like, or rather, glutinous, in appearance.

I put this second parcel in a vial, and placed it in water, on the sand bath, at the temperature of the stomach, (100° Fahrenheit,) as indicated by the thermometer immediately preceding its extraction, and continued it there.

At 5 o'clock, took out another quantity. Diges- tion had advanced in about the same ratio as from the first to the second time of extracting ; and when compared with the second parcel, contained in the vial on the bath, little or no difference could be per- ceived in them ; both were nearly in the same stage

OB8ERVAT\ONS. 143

of digestion. That contained in the vial had ad- vanced regularly and rapidly ; nearly all the particles of meat had disappeared, become chymified, and changed into a reddish brown sediment, suspended in the more fluid parts, with small particles, resem- bling loose, white coagula), floating about near the surface.

On taking out the third parcel, small pieces of ve- getables appeared, in a partial stage of digestion. This was also put into a vial, and placed on a bath, with the second parcel, and the same uniform tem- perature (100°) kept up, with frequent, gentle agita- tion.

At 6 o'clock, P. M., digestion had progressed e- qually in both. The only difference to be seen, was the particles of vegetables, in a less advanced stage than the meat.

The contents of both vials, kept on the bath, and nearly in the same temperature, until the next morn- ing, were completely digested, except the few small particles of vegetables, which remained almost en- tire.

The contents of the vials, at this time, were of the consistence of thin jelly, and of a lightish brown co- lour ; tasting pccuharly insipid, saltish and acid. Af- ter standing at rest awhile, the brownish sediment subsided towards the bottom, while small particles of whitish coloured, loose coagulse floated about in the fluid above. The undigested particles of vege- tables settled to the bottom.

In the Preliminary Observations, I have endeavour- ed to maintain the proposition, that chyme is hoino- o-eneous in its properties. It would seem from this and some other experiments, that it contains a sedi- ment. This, however, it is believed, does not mili- tate against its homogeneous character. Many sub- stances, that are generally acknowledged to possess

144 EXPERIMENTS AND

this character, deposit a sediment, dh standing. 'The heavier parts subside, of course. It is not necessary to cite examples. It is possible, also, that mixed food contains some adventitious, indigestible substances, which arc not aflected by the gastric juice.

This Experiment (26th) demonstrates the com- parative digestibility of animal and vegetable diet. In extracting two parcels, one in fifteen minutes and the other in three quarters of an hour, the meat only made its appearance, partially digested. In taking out a third portion, at 5 o'clock, two hours after ha- ving eaten, small particles of vegetables made their appearance. This experiment appears to confirm the opinion, pretty generally entertained by medical men, that vegetables are less easily disposed of by the gastric organs, than animal or farinaceous sub- stances. With dyspeptics this is undoubtedly true, as experience every day teaches us ; and as their stomachs have the same organization as others, are governed by the same general laws, and are only mo- dified by debility or disease, the conclusion is natu- ral, that they should act on aliment in the same man- ner, in proportion to their strength, that the liealthy stomach does.

It may be inferred from this experiment, that the more perfectly chymified portions of food rise to the superior part of the stomach, as suggested in a pre- vious observation, and are consequently exposed at the perforation, from whence parcels are taken for experiment and examination.

OBSERVATIONS. ^i^

Experiment 27.

March 17. At 12 o'clock,M.— drank half a pint, of jnilk. In fifteen minutes, took a portion out of the stomach, in a line, loosely coagulated condition, per fectly white, and suspended in a semi-transparent, whey coloured fluid. I placed this on the bath, and it continued to digest for eight hours, when the co- agulcB were completely taken up. A very small pro- portion of light coloured sediment, settled loosely to the bottom of a cream coloured, sweetisii fluid.

At the same time that he drank the milk, I put one drachm of gastric juice, warm from the stomach, into two drachms oimilk, and placed it on the bath, at the natural temperature, (100^ Fahrenheit.) In five mi- nutes, pure, white coagulaj formed, which, in fifteen minutes, exactly resembled that taken out of the sto- mach. In twenty minutes, the same fine, loose coa- gulae were suspended in a similar liquid. These two drachms of milk, mixed with one drachm of pure gastric juice, out of the stomachy gave the same result, and exhibited the same appearance, in nearly the same time, as that which was swalloiueiL and taken from the stomach. Scarcely ashade of difference could be perceived in four hours.

Two drachms of milk, coagulated by acetous acids produced coagulaB very similar to the other ; but the wheyey part bore no resemblance, except in mere fluidity ; that formed from the gastric fluid being of an opaline, slightly yellowish cast, and the other thin, transparent and watery.

The coagulse formed by the gastric juice, contin- ued to digest regularly in their fluid, for about eight hours, when they were completely taken up, and con- verted into chyme.

The coagulaj formed by the vinegar, remained in the same condition for forty eight-hours, with no other change except mere subsidence below the wa- tery fluid.

T

4

146 EXPERIMENTS AND

It is well known, and this experiment was not ne- cessary to prove it, that milk is coagulated before it receives the solvent action of the gastric juice. But it has some degree of importance in demonstrating the fact, that a degree of sohdity is necessary for the operation of this agent. And it is a strong argument against the doctrine of digestion by the veins of the stomach. It has been maintained by some, that the veins take up the nutritious parts of the food, immediately on their introduction into the stomach. If so, it strikes me that they should do so, as it relates to this kind of aliment, while they are in a fluid state, and more susceptible of absorption by their mouths ; and not wait till they have become so- lidified. Wine, spirits, water and other fluids, which conduce nothing towards alimentation, arc neither coagulated, nor otherwise aflected by the gastric juice. These fluids are not digested ; and probably enter the circulatory system without much change.

It will be seen, by succeeding experiments, that other fluid, nutritive substances, particularly the albu- men of eggs, are coagulated before they receive the solvent action of the gastric juice.

Experiment 28.

Jan. 25, 1831. At 1 o'clock, P. M.,he ate a full din- ner of roast becf^ potatoes, beets and bread, and kept ex- ercising about his usual employment, as house ser- vant.

At 5 o'clock, 25 ms., I took out a portion of the con- tents of the stomach. Digestion of the different ar- ticles of food had commenced, and considerably advanced. The bread, reduced to a pultaceous con-

OBSERVATIONS. 147

dition, appeared floating about in a reddish brown fluid, of a glutinous consistence. A few small par- ticles of the meat could also be seen in the fluid. None of the vegetables were discernible at this time. The fluids tasted slightly acid, giving the flavour pe- culiar to dilute muriatic acid, and very slightly bit- ter. A few grains of carbonate of soda, thrown into a drachm or two of this fluid, produced a slight efler- vescence.

At 4 o'clock, 20 mins. — took out another portion, a shade or two darker than the first. This dark co- lour of the chyme, I attributed to his having taken with his dinner, some of the outside, scorched pieces of the beef

No distinct parts of the food could be seen at this time. Upon the surface of both parcels of fluids, floated a layer, of an oily or lardaceous consistence, which probably was the remains of the fat pork which he had eaten for his breakfast. The first parcel con- tained much more of this oily fluid than the last ; which leads me to think that a considerable portion of an imperfect chyme, formed from the pork taken at about 10 o'clock, for breakfast, remained in his stomach when he ate his dinner ; and then mixed with this aliment, in an imperfect state of digestion.

At 5 o'clock, 30 mins.— tried to extract another por- tion— could obtain nothing, except a little gastric juice. The chyme formed from his dinner appeared to have all passed from the stomach.

Experiment 29.

March 6. At 9 o'clock, A. M. — breakfasted onveni- ison steak, cranberry jelly and bread, and drank a pint of cofee.

Twenty minutes after eating, I took a portion from the stomach, in an incipient stage of digestion. Pla- ced this on the bath.

At 9 o'clock, 45 ras.-took out another portion, in an

148 "" EXPERIMENTS AND

advanced stage of digestion — very few small particles of food were discernible.

At 10 o'clock, 10 mins. — took out another portion, completely chymificd.

At 10 o'clock, 35 mins. — the stomach was entirely empty and clean — no chyme or aliment to be found in it. The breakfast, eaten at 9 o'clock, was all digested, and had passed through the pylorus, in one hour and thirty-Jivc minuics.

This is an example of the great rapidity of diges- tion in some instances. This rapidity depends upon various circumstances — principally upon moderation in quant ty, and the digestible properties of the food used. From various trials, I am confident, ge- nerally speaking, that venison is the most digestible of any diet of the fibrinous kind. In a few instances, it will be perceived, that other articles of diet were disposed of in a shorter period, than the venison waa in this experiment.

Experiment 30.

March 7. Mixed two drachms of albitmen of a fresh egg, with two drachms of gastric juice, warm from t!;e stomach, and placed it on the bath, at the natural temperature. The juice and the albumen were so much alike in their appearance, when first mixed, that the change was not perceptible ; but in ten or fifteen minutes, small, white flocculi began to appear, floating about; and the mixture became of an opaque and whitish appearance. This continued slowly and uniformly to increase, for three hours, at which time, the fluid had become of a milky appear- ance ; the small flocculi, or loose coaguls, had most- ly disappeared, and a little light coloured sediment subsided to the bottom.

OBSERVATIONS. 149

At the same time of the above experiment, he swallowed the ivhife of two eggs, unmixed with any other food. The stomach was perfectly empty at the time.

In thirty minutes, I took out and examined a por- tion. It exhibited a similar appearance to that mix- ed out of the stomach, in the vial on the bath, only more rapid in its progress.

In one hour and thirtij minutes, I examined the cavity of the stomach, and found nothing but a little pure gastric juice. The albumen was completely digest- ed, and disposed of.

Experiment 31.

March 9. At 8 o'clock, A. M. — stomach empty — temperature 98° — took out two ounces gastric juice. Divided this into two equal parts, and put them into separate vials — to each of which, I put equal quan- tities of roasted beef— placed one of them on the bath, at 99°, and the other in the open air, at 34°.

I then put the same quantity of the meat into an equal quantity of clear water, and placed it with the cold gastric juice and meat in the open air, at the same temperature.

At 9 o'clock, he had finished breakfasting on the same kind of meat, with the addition of warm, light bismit, butter, and a pint of coffee. Temperature of the stomach, immediately before eating, 100°. In thirty minutes after eating, the temperature rose to 102°.* Digestion rapidly advancing.

At 10 o'clock — took out a portion, partially digest- ed ; the biscuit the most so of any part of the break- fast. Placed this on the bath.

The meat, contained in the vial of gastric juice on the bath, was, at this time, in about the same condi- tion as that taken from the stomach ; very little dif-

* Probably the effect of exercise, but not noticed at the time,

150 EXPERIMENTS AND

ference could be perceived. The biscuit which he had eaten with his breakfast occasioned the only dif- ference ; that being reduced to a soft pulp.

The meat in the cold gastric juice was, at this time, much less advanced, than either that in the warm juice, or in the portion taken from the sto- mach.

That contained in the vial of water was merely macerated, and had no more appearance of diges- tion than what was eflected by its being masticated, and mixed with the saliva, as were the other pieces of meat, before they were put into the gastric juice.

At 10 o'clock, 45 mins. I examined the stomach, but could find no distinct particles of food, and but very little chyme. His breakfast appeared to have been completely digested, and had left the stomach. Tem- perature 100°.

At 2 o'clock, P. M., the several parcels of meat placed in the gastric juice, on the bath, being about half digested, and appearing not to progress, I drew off twelve drachms of gastric juice from the empty stomach, and added foiir drachms to each, including the parcel taken from the stomach, at 10 o'clock, A. M..that being in about the same state of chymifica- tion with the others on the bath. • I continued the two on the bath, at 100°, and the others, (cold gastric and aqueous fluids) on the shelf, at 34°. Digestion evidently recommenced in the parcels on the bath, and again regularly progressed, after the addition of the second portions of the gas- tric juice ; and more rapidly in the vial containing the meat digesting in the gastric juice, taken out of the stomach first, than in the one containing the chy- mous portion, taken out at 10 o'clock, A. M., one hour after having eaten. This parcel, however, con- tained a solid piece of meat, which appeared to have been swallowed without being masticated; and con- sequently did not readily yield to the solvent action of the gastric juice. The juice was, also, in too small proportion completely to digest it.

OBSERVATIONS. 151

The vials containing the cold aqueous and gastric portions, placed on the shelf, were, at 4 o'clock, P. M., but very little changed, and much alike.

These four parcels, after standing for twenty-four hours, and all suffered to get cool, exhibited the fol- lowing appearances.

The portion taken from the stomach at 10 o'clock, A. M., one hour after having eaten, was the most perfectly digested, and completely converted into a thick puhaceous mass, of a reddish brown colour, with the exception of the piece of unmasticated meat, which remained entire and undigested, This emit- ted a sharp, rancid smell, and was slightly bitter. The vial containing the meat digesting in the gastric juice first taken out of the stomach, exhibited ap- pearances very similar to the last, though the contents were less perfectly digested. It was not of so thick consistence; but gave tlie same sharp smell and bit- ter taste, with the addition of an empyreumatic and slightly fffitid flavour. The empyreuma, I attributed to a portion of the meat being a httle dry and scorched when first put in ; and the I'cetor, to the temperature of the bath having been accidentally raised consider- ably above 100°, during the experiment.

The cold gastric and aqueous portions very nearly resembled each other ; botli macerated, but not digest- ed ; diflTering essentially from the other two, in not ex- hibiting any appearance of chyme. The cold gastric juice had very little, if any, more effect on the meat, than the water; and retained its peculiar taste. Its colour was darkish brown, while the latter was of a reddish grey. At 9 o'clock, A. M., of the 10th, I placed both of them on the bath, and continued them for twenty-four hours, at the natural temperature. An essential difference in the gastric liquor was pro- duced, after being placed on the bath. Digestion evidently advanced ; the colour l)ecame lighter and hghter; the meat diminished; and a thin, light, paste- like liquor formed, as in the other two portions, at first placed on the bath. The aqueous portion ex-

152 EXPERIMENTS AKD

hibited no other appearance than that of simple ma- ceration in warm water. At the end of the last twen- ty-four hours, on the bath, appearances of incipient putrefactive fermentation began to be manifested, as the evolution of small bubbles of foetid gas, and a change of colour from a reddish to a greenish shade.

A difference in the degrees of chymification be- tween the several parcels, was now very evident.

The gastric portion, or that taken from the sto- mach, an hour after breakfast, \vas the most diges- ted.

The artificial, or that portion of the gastric juice and meat, first placed on the warm bath, was next, and nearly as much digested ; though a difference was observable.

The third, or portion of gastric juice and meat, first placed in a cool situation, after having bfeen on the warm bath for six or eight hours, was the next, but considerably less digested than the second.

The fourth, or aqueous portion, exhibited