MEDICAL

Gift of
The Sutter Hospital

MEDICAL WORKS

PUBLISHED BY

& COMPVAJSTY.

Bellevue and Charity Hospital Reports.

One vol., 8vo. Cloth ..... A . AA

.......................... $4.00

Mediterranean.

8.50

Onevo,.,8ro.

Flint's Physiology.

Cloth. 'Per vol ............ .........

v<o & Youmans>s Physiology and Hygiene.

(Vol. 4. In press.) 8vo. Cloth. 'Per vol

2.00

Letterman's Recollections of the Army of the
Potomac.

)ne vol., 8vo. Cloth .......

............ ............ AOO

Maudsley on the Mind.

One vol., 8vo. Cloth ............. ...... . ........ 4 5Q

Meyer's Electricity.

One vol., 8vo. Cloth .....

...................... 4.00

Niemeyer's Practical Medicine.

Two vols., 8vo. Cloth ____ ,

'* .............. •••.... y.uo

Sayre's Club-Poot.

One vol., 12mo. Cloth. . . .

Tilt's Uterine Therapeutics.

One vol., 8vo. Cloth ____

*"** •" ........ •••-....... O.u\)

Vogel's Diseases of Children

One vol., 8vo. Cloth...

4.50

In Press.

Flint's Manual on Urine, I Elliot's Hygiene of Infancy,

Barnes's Obstetric Observations, Hammond's Diseases of the Mind.

*** Any of these works will be mailed, post-free, to any part of the United States, on receipt
of tlie price. Catalogues forwarded on application.

D. APPLETON & CO.,

90, 92 & 94 Grand St., New York.

NEW YORK MEDICAL JOURNAL,

The Largest Medical Monthly Published.

TERMS, $4.00
Numbers sent by

II.

THE*

JOURNAL OF PSYCHOLOGICAL MEDICINE-

AWsx£££r--- — — '

AND ANTHROPOLOGY,

ed Quarterl, each n^ eon taMng not less 208 paRes, ^

large volume annually.
Tern,*, $3 per An

CLTJB

, and the VEW OKK ^ T
and APp- Jo*L«, $8 K""Al' $? !

PREMIUM PORTRAIT

inches, of the dM

is dedicated to the Med a, P °' ' °HN W'FE1™!S- This Portrait

"

or othmvise' shouid

D. APPLETON & CO.,

99, 92 «• 94 Grand St., New York.

V

PHYSIOLOGY OF MAN;

*--> , >

DESIGNED TO REPRESENT

THE EXISTING STATE OF PHYSIOLOGICAL
SCIENCE,

AS APPLIED

TO THE FUNCTIONS OF THE HUMAN BODY.

BY

AUSTIN XINT, Ja., M.D.,

PEOFESSOE OP PHYSIOLOGY AND MICEOSCOPY IN THE BELtEVTTE HOSPITAL MEDICAL COLLEGE,

NEW YOEK, AND IN THE LONG ISLAND COLLEGE HOSPITAL ; FELLOTV OF THE

NEW YOEK ACADEMY OF MEDICINE ; EESIDENT MEMBER OF THE LYCEUM

OF NATUBAL HISTOEY IN THE CITY OF NEW YOEK, ETC., ETC.

ALIMENTATION; DIGESTION; ABSOKPTION;
LYMPH AND CHYLE.

KEW YORK:
D. APPLETON AND COMPANY,

90, 92 & 94 GRAND STREET.
1869.

ENTERED, according to Act of Congress, in the year 1867, by

D. APPLETON & CO.,

In the Clerk's Office of the District Court of the United States for the Southern District
of New York.

Y,2-

PREFACE.

IN the preface to the first part. of this work, published a
little more than a year ago, the author announced his inten-
tion of writing an extended treatise upon human physiol-
ogy ; and the present volume, devoted to subjects connected
with the great functions of digestion and absorption, is now
presented, as the second of the series. As stated in the
preface to the first volume, the separate parts of the work
are intended to form distinct treatises, devoted respectively
to natural subdivisions of the science of physiology ; each
one being complete in itself, but the entire series embracing
all the subjects usually regarded as belonging to human
physiology. The manner in which the first part has been
received, and the experience of the author in the prepara-
tion of the present volume, have encouraged him. in carrying
out the original plan of the work. To give to every sub-
division of physiology that careful reflection and critical
study, which alone could enable one to form a calm and
dispassionate judgment upon the difficult questions which
are constantly arising, involves an amount of time and
patient labor which might well discourage the most en-
thusiastic student. A work of such magnitude, however,

4 PEEFACE.

can be accomplished much more efficiently, by dividing it
into separate and. distinct parts. By publishing each part
separately, the whole subject of human physiology, great as
it is, may be considered with a degree of elaborateness
which is generally looked for only in special treatises.
This does not necessarily involve great voluminousness ;
on the contrary, it frequently happens that subjects, the
literature of which is excessively abundant, may be con-
sidered, from a practical and positive point of view, in a
comparatively small space, ignoring nothing that is valu-
able, and taking pains only to compare and harmonize con-
flicting experiments and observations. A practical acquaint-
ance with experimental methods of observation frequently
enables the physiologist to accomplish this end, and thus re-
lieve certain complicated questions of much of their obscurity.
The subjects taken up in the present volume form a
subdivision of physiology of the greatest importance and
interest, to the general as well as to the professional
reader. The first of these, alimentation, does not always
receive sufficiently extended consideration in works upon
physiology; though it is evident that the properties and
physiological relations of matters which are destined to be-
come part of the living body can hardly be studied too
closely. The effects of improper and insufficient alimenta-
tion, also, which are too often observed in the poorer classes,
particularly in large cities, are of the highest importance.
The author, through the kindness of Dr. W. H. Yan Bu-
ren, of the United States Sanitary Commission, has been
enabled to present some important physiological facts con-
nected with the celebrated Anderson ville prison, noted on
the spot by Prof. Joseph Jones, M. D., formerly of Georgia,

PREFACE. 5

who was appointed during the late war by the medical
authorities at Richmond to report upon the condition of
the prisoners confined in the stockade. Such an opportunity
for observing the effects of improper and insufficient alimen-
tation upon large bodies of men has never been presented
before, and probably will never occur again.

In studying the subject of digestion, many points pre-
sented themselves which were complicated by a mass of
conflicting observations and statements by the earlier
physiologists, and even by modern experimenters ; and there
are, even now, serious differences of opinion with regard to
some of the most important facts connected with this func-
tion. This is strikingly illustrated in the views of different
writers of high authority concerning the physiological prop-
erties of the saliva, the gastric juice, the bile, and the secre-
tion of the pancreas. Much of this confusion is to be
avoided, however, by treating of these questions upon the
basis of accumulated experimental facts, without regarding
mere opinions, even of the highest authority, when based
upon insufficient data.

"With regard to absorption, very much has been devel-
oped within the last few years by accurate experimental
researches, in which some of the sources of error in the ear-
lier observations have been avoided, by remarkably success-
ful experiments upon living animals, and by the applica-
tion of improved methods for the analysis of the animal
fluids. Recognizing the importance of all these methods of
study, the author has endeavored to give the most extended
application of physical laws to the mechanism of absorption,
without losing sight of the fact that the physical phenomena,
presented in the living body are by no means fully understood.

O PEEFACE.

Our positive knowledge concerning many of the functions
considered in the present volume dates from important dis-
coveries. The author has in all cases made it his duty to
trace these discoveries to their original sources ; but in his
historical researphes, he has often found that the reputed
authors of important original observations had, generally
without their knowledge, been anticipated. The only object
in making references to the works of the earlier physiologists
has been to do justice, as far as possible, to every original
observer ; and all the works cited in foot-notes have, without
exception, been consulted by the author personally, in the
original, and the references clearly indicated.

Most of the important. facts connected with the functions
of digestion and absorption have been repeatedly verified by
the author in his laboratory and in public demonstrations ;
and in many instances, the observations of others have been
more or less extended. The most important original obser-
vations, however, are upon the excretion of cholesterine in
the bile, and its transformation into stercorine in its passage
through the intestinal canal. In the present volume, this
question is considered in connection with the digestive func-
tion of the bile and the composition of the faeces. It will be
considered much more elaborately, under the head of Excre-
tion, in another volume.

The succeeding volumes of the series will be devoted to
Secretion and Excretion, Nutrition, Movements, etc., the
Nervous System, and Generation. They will appear as
rapidly as is consistent with their careful preparation.

NEW YORK, June, 1867.

CONTENTS.

CHAPTER I.

HUNGEE, THIEST, AND INANITION.

General considerations — Appetite — Circumstances which modify the appetite —
Influence of climate and temperature — Influence of exercise and occupation
— Influence of habit— Influence of alcohol, tobacco, etc. — Influence of extir-
pation of the spleen, or of one kidney — Hunger — Location of the sense of
hunger — Thirst — Location of the sense of thirst — Inanition — Loss of weight
in inanition — Effects of inanition on circulation, respiration, animal tempera-
ture, and the nervous system — Duration of life in inanition — Insufficient ali-
mentation, , Page 13

CHAPTER II.

ALIMENTATION.

General considerations — Division of alimentary principles — Nitrogenized aliment-
ary principles — Musculine — Albumen — Caseine — Fibrin — Gelatine and Chon-
drine — Vegetable albumen, fibrin, and caseine — Gluten — Non-nitrogenized
alimentary principles — Sugar — Starch — Vegetable principles resembling
starch — Fats and oils — Inorganic alimentary principles — Water — Chloride of

sodium — Phosphate of lime — Iron, 44

^

CHAPTER HI.

COMPOUND ALIMENTAEY SUBSTANCES.

General considerations — Aliments derived from the animal kingdom — Meats —
Animal viscera — Animal products used as food — Eggs — Milk — Butter — Cheese
—Fishes, reptiles, mollusks, and Crustacea — Preparation of animal articles of
food — Aliments derived from the vegetable kingdom — Cereal grains — Bread
— Leguminous roots, leaves, seeds, etc. — Condiments and flavoring arti-
cles, V 67

8 CONTENTS.

CHAPTER IV.

DBINKS — QUANTITY AND QUALITY OF FOOD.

Water — Alcohol — Distilled liquors— Wines, malt liquors, etc. — Coffee — Tea —
Chocolate — Quantity and variety of food necessary to nutrition — Necessity
of a varied diet, . ...,'. . . . . Page 101

CHAPTER V.

DIGESTION — PKEHENSION AND MASTICATION.

General arrangement of the digestive apparatus — Prehension of solids and
liquids — Mastication — Physiological anatomy of the organs of mastication —
Enamel of the teeth — Dentine — Cement — Pulp-cavity — Arrangement of the
teeth — Anatomy of the maxillary bones — Temporo-maxillary articulation —
Muscles of mastication — Muscles which depress the lower jaw — Action of the
muscles which elevate the lower jaw and move it laterally and antero-pos-
teriorly — Action of the tongue, lips, and cheeks in mastication — Summary of
the process of mastication, . .V 133

CHAPTER VI.

INSAIIVATION.

General considerations— Parotid saliva — Relations of the parotid secretion to
mastication — Submaxillary saliva — Relations of the submaxillary secretion
to mastication and gustation — Sublingual saliva — Fluids from the smaller
glands of the mouth, tongue, and fauces — Mixed saliva — Quantity of saliva —
General properties and composition of the saliva — Functions of the saliva- —
Action of the saliva on starch — Mechanical functions of the saliva, . 155

CHAPTER VII.

DEGLUTITION.

Physiological anatomy of the parts concerned in deglutition — Pharynx — Muscles
of the pharynx — Muscles of the soft palate — Mucous membrane of the phar-
ynx—(Esophagus — Mechanism of deglutition — First period of deglutition —
Second period of deglutition — Protection of the posterior nares during the
second period of deglutition — Protection of the opening of the larynx — Func-
tion of the epiglottis — Study of deglutition by auto-laryngoscopy — Third period
of deglutition — Intermittent contraction of the lower third of the oesophagus
— Nature of the movements of deglutition — Deglutition of air, . .181

CONTENTS. 9

CHAPTER VIII.

STOMACH-DIGESTION — GASTKIO JUICE.

Physiological anatomy of the stomach — Peritoneal coat — Muscular coat — Mucous
coat — Glandular apparatus in the stomach — Gastric tubules — Mucous follicles
— Closed follicles — Gastric juice — Mode of obtaining the gastric juice — Gas-
tric fistula in the human subject — Secretion of the gastric juice — Secretion in
different parts of the stomach — Quantity of gastric juice — Composition of
the gastric juice — Organic principles of the gastric juice — Source of the
acidity of the gastric juice — Ordinary saline constituents of the gastric
juice, . . . .Page 208

CHAPTER IX.

ACTION OF THE GASTEIO JUICE IN DIGESTION.

Constituents on which the activity of the gastric juice depends — Action of the
gastric juice upon meats — Action upon albumen, fibrin, caseine, and gelatine
— Action upon vegetable nitrogenized principles — Albuminose, or peptones —
Action of the gastric juice on fats — Action on saccharine and amylaceous prin-
ciples— Duration of stomach-digestion — Digestibility of different aliments in
the stomach — Action of the gastric juice upon the coats of the stomach —
Circumstances which influence stomach-digestion, 251

CHAPTER X.

MOVEMENTS OF THE STOMACH.

Character of the contractions of the muscular coat of the stomach — Movements
in the cardiac and in the pyloric portion — Mechanism of the movements of
the stomach — Rumination, and regurgitation from the stomach — Rumination
in the human subject— Vomiting — Mechanism of vomiting — Condition of the
stomach during the act of vomiting — Action of the diaphragm in vomiting —
Action of the abdominal muscles in vomiting — Action of the oesophagus in
vomiting — Summary of the muscular action which takes place in vomiting —
Eructation, . . . .287

CHAPTER XL

INTESTINAL DIGESTION.

Physiological anatomy of the small intestine— Size of the small intestine— Divi-
sions of the small intestine — Mucous membrane of the small intestine — Val-

10 CONTENTS.

vulae conniventes — Glands of Brunn — Intestinal tubules, or follicles of Lieber-
kiihn — Intestinal villi — Solitary glands, or follicles, and the patches of Pejer
— Intestinal juice — Secretion of the solitary and agminated glands — General
properties of the intestinal juice — Action of the intestinal juice in diges-
tion, .' Page 308

CHAPTER XII.

PANCEEATIC JUICE.

Pancreatic ducts — Mode of obtaining the pancreatic juice — General properties
and composition of the pancreatic juice — Alterations of the pancreatic juice —
Action of the pancreatic juice in digestion — Action upon fats — Destruction
of the pancreas — Cases of fatty diarrhoea — Action of the pancreatic juice
upon starchy and saccharine principles — Action upon nitrogenized principles
— Summary of the functions of the pancreas in digestion, . . 330

CHAPTER XIII.

ACTION OF THE BILE IN DIGESTION — MOVEMENTS OF THE SMALL
INTESTINE.

Question of the excrementitious or recrementitious character of the bile — Liga-
tion of the ductus communis choledicus — Biliary fistula — General constitu-
tion of the bile — Observations on a dog with biliary fistula — Variations of the
bile with digestion — Movements of the small intestine — Peristaltic and anti-
peristaltic movements — Cause of the movements of the small intestine —
Function of the gases in the small intestine — Peristaltic movements after
death — Influence of the nervous system upon the peristaltic movements, 360

CHAPTER XIV.

ACTION OF THE LAEGE INTESTINE.

Physiological anatomy of the large intestine — Divisions of the large intestine —
Ileo-csecal valve — Digestion in the large intestine — Contents of the large in-
testine— Composition of the fteces — Microscopic characters of the fceces — Ex-
cretine and excretoleic acid — Stercorine — Origin of stercorine — Summary of
the constitution of the faeces — Movements of the large intestine — Defecation
— Action of the sphincter and the levator ani — Gases found in the alimentary
caual — Origin of the intestinal gases, 383

CONTENTS. 11

CHAPTER XV.

ABSOKPTION.

General considerations — Absorption by blood-vessels — Absorption by lacteal and
lymphatic vessels — Physiological anatomy of the lacteal and lymphatic sys-
tem— Thoracic duct — Structure of the lacteal and lymphatic vessels — Lym-
phatic glands — Absorption of albuminoids by the lacteals — Absorption of
glucose and salts by the lacteals — Absorption of water by the lacteals — Ab-
sorption from parts not connected with the digestive system — Absorption
from the skin — Absorption from the respiratory surface — Absorption from
closed cavities, reservoirs of glands, etc. — Absorption of fats and insoluble
substances — Variations and modifications of absorption — Influence of the
condition of the blood and the vessels on absorption — Influence of the ner-
• vous system on absorption, Page 415

CHAPTER XVI.

IMBIBITION AND ENDOSMOSIS.

General considerations — Imbibition by animal tissues — Mechanism of the passage
of liquids through membranes — Observations anterior to those of Dutro-
chet — Experiments of Dutrochet — Conditions necessary to endosmosis and
exosmosis — Influence of membranes upon osmotic currents — Capillary attrac-
tion— Imbibition by porous substances — Endosmosis through porous septa —
Endosmosis through animal membranes — Endosmosis through liquid septa —
Electrical theory of endosmosis — Influence of different liquids upon osmotic
currents — Diffusion of liquids — Endosmotic equivalents — Modifications of en-
dosmosis— Modifications due to the extent and the thinness of the permeahle
membrane — Modifications due to pressure and the movements of liquids —
Modifications due to variations in temperature — Modifications induced by elec-
tricity— Application of physical laws to the function of absorption — Transu-
dation, 469

*

CHAPTER XVH.

LYMPH AND CHYLE.

Mode of obtaining lymph — Quantity of lymph — Properties and composition of
lymph — Alterations of the lymph — Influence of starvation upon the lymph —
Corpuscular elements of the lymph — Leucocytes — Development of leucocytes
in the lymph and chyle — Globulins — Origin and function of the lymph-
Chyle — General properties of the chyle — Composition of the chyle — Compar-
ative analyses of the lymph and the chyle — Microscopical characters of the

12 CONTENTS.

chyle — Movement of the lymph and the chyle — Pressure of fluids in the
lymphatic system — General rapidity of the lymphatic circulation — Causes of
the movement of the lymph and chyle — Influence of the forces of endosmosis
and transudation — Influence of the contractile walls of the vessels — Influ-
ence of pressure from surrounding parts — Influence of the movements of
respiration, ' , . Page 507

PHYSIOLOGY OF MAR

CHAPTEE I.

HTJNGEK, THIEST, AST) INAOTTION.

General considerations — Appetite — Circumstances which modify the appetite-
Influence of climate and temperature — Influence of exercise and occupation
— Influence of habit — Influence of alcohol, tobacco, etc. — Influence of extir-
pation of the spleen or of one kidney — Hunger — Location of the sense of
hunger — Thirst — Location of the sense of thirst— Inanition — Loss of weight
in inanition — Effects of inanition on circulation, respiration, animal tempera-
ture, and the nervous system — Duration of life in inanition — Insufficient ali-
mentation.

THE power of self-regeneration is one of the great dis-
tinctive properties belonging to all organized living bodies.
In the organism of animals, every part is continually under-
going what may be called physiological decay ; the organic
nitrogenized principles are being constantly transformed into
effete matter; and as these principles never exist without
inorganic principles, with which they are closely and insep-
arably united, it is found that the products of their decay
are always discharged from the body in combination with in-
organic matters. This process of molecular change is a ne-
cessary and inevitable condition of life. Its activity may be
increased or retarded by various means, but it cannot be
arrested. The excrementitious principles which are thus
formed are produced constantly by the tissues, and must be
continually removed from the organism, otherwise they

14: ALIMENTATION.

accumulate and induce serious toxic conditions. Examples
of this are found in those diseases of the kidneys which in-
terfere with the elimination of urea, producing ursemic poi-
soning, and in diseases of the liver which interfere with the
elimination of cholesterine, giving rise to cholestersemia.

It is evident from the amount of matter which is daily
discharged from the body that the process of destructive
assimilation, as it is sometimes called, must be very active.
Its constant operation necessitates a constant appropriation
of new matter by the parts, in order that they may main-
tain their integrity of composition, and be always ready to
perform their functions in the economy. The blood con-
tains all the principles necessary for the regeneration of the
organism. Its inorganic constituents are generally found in
the same form in which they exist in the substance of the
tissues; but the organic principles of the parts are formed
in the substance of the tissues themselves by a transforma-
tion of material furnished by the blood. The physiological
decay of the organism is, therefore, being constantly re-
paired by the blood ; but in order to keep the great nutri-
tive fluid from becoming impoverished, the materials which
it is constantly losing must be supplied from some source
out of the body, and this necessitates the ingestion of matters
which are known as food. Food is taken into the body in
obedience to a want on the part of the system which is
expressed by the sensation of hunger, when it relates to
solid or semi-solid matters, and thirst, when it relates to
water. As these sensations are the first cause of the intro-
duction of the materials capable of regenerating the blood,
their consideration naturally precedes the study of digestion,
the process by which the articles of food are prepared for
absorption and appropriation by the circulating fluid.

Hunger and Thirst.

The term hunger may be applied to all degrees of that
peculiar want felt by the system which induces the ingestion

HUNGER AND THIEST. 15

of nutritive principles. Its first manifestations are, perhaps,
best expressed by the term appetite ; a sensation by no means
disagreeable, and one which may be excited by the sight,
smell, or even the recollection of savory articles, at times
when it does not absolutely depend on a want in the system.
In the ordinary and moderate development of the appetite, it
is impossible to say that the sensation is located in any dis-
tinct part or organ. It is influenced in some degree by habit ;
in many persons, the feeling being experienced at or near
the hours when food is ordinarily taken. If not soon grati-
fied, the appetite is rapidly intensified until it becomes
actual hunger. Except when the quantity of food taken is
unnecessarily large, the appetite simply disappears on the
introduction of food into the stomach, and gives place to the
sense of satisfaction which accompanies the undisturbed and
normal action of the digestive organs ; or, in those who are in
the habit of engaging in absorbing occupations at that time,
the only change experienced is the absence of desire for food.
The sense of oppression and fulness which attends over-dis-
tension of the stomach is simply superadded to the feeling of
satisfaction of the appetite, and is not a necessary part of it.

In man, the appetite is usually manifested in a marked
degree at least twice, and generally three times, in the
twenty-four hours. In this country, food is commonly taken
three times daily. In childhood, when the system demands
material, not only for the repair of worn-out parts, but for
growth, food is generally taken oftener and in larger rela-
tive quantity than in the adult. The infant should satisfy
the appetite at least six or seven times in the twenty-four
hours ; and nothing has a more serious influence upon the
development of the growing child than bad quality or a
restricted quantity of food.

It has been observed that children and old persons en-
dure deprivation of food by no means so well as adults.
This fact was noted by M. Savigny in the case of the wreck
of the frigate Medusa. After the wreck, one hundred and fifty

16 ALIMENTATION.

persons, of all ages, were exposed on a raft for thirteen days
with hardly any food. Out of this number only fifteen sur-
vived, among them M. Savigny, and the children, young
persons, and the aged, were the first to succumb.1

Important modifications in the appetite are due to tem-
perature. In cold climates, and during the winter season in
all climates, the desire for food is notably increased, and the
tastes are somewhat modified. Animal food, and particu-
larly fats, are more agreeable at that time, and the quantity
of nutriment which is demanded by the system is then con-
siderably greater. In many persons, the difference in the
appetite in warm and cold seasons is very marked, and they
habitually lose flesh in the summer and regain it in the winter.

Exercise and occupation, both mental and physical, when
not pushed to the point of exhaustion, increase the desire for
food and undoubtedly facilitate digestion. Certain articles, es-
pecially the vegetable bitters, taken into the stomach imme-
diately before the time when food is habitually taken, frequent-
ly have the same effect; while other articles, which do not
satisfy the requirements of the system, have a tendency to
diminish the desire for food. Many articles of the materia
medica, especially preparations of opium, have, in some per-
sons, a marked influencp in diminishing the appetite. The
abuse of alcoholic stimulants will sometimes take away all
desire for food. When hunger is pressing, it has been ob-
served that tobacco, in those who are accustomed to its use,
will frequently allay the sensation for a time.2 When the

1 SAVIGNY, Observations sur les Effete de la Faim et de la Soif, eprouvles
apres le Naufrage de la Fregate du Hoi, la Meduse, en 1816. These, No. 84,
Paris, 1818.

8 In this connection, the experience of Dr. W. A. Hammond, who was de-
layed for a number of hours on the railroad between Philadelphia and New
York, is very instructive. On this occasion, Dr. Hammond was deprived of
food for twenty-eight hours. During this time, when the sense of hunger be-
came very intense, he obtained marked though temporary relief by smoking
tobacco. This he repeated several times, always with the same result. (Ver-
bal communication.) - .

HUNGER AND THERST. 17

system has been badly nourished from any cause, as after
prolonged abstinence, or in recovery from an exhausting dis-
ease, hunger is generally pressing and almost constant ; and
this continues until the organism has regained its normal con-
dition. Under these circumstances, the ingestion of food,
even in unusually large quantity, has but a momentary
eifect in appeasing the appetite ; showing that though the
feeling of satiety which follows the introduction of a suf-
ficient quantity of food into the stomach is experienced, the
system still feels the want of nourishment, and this want is
expressed by an almost immediate recurrence of the appe-
tite.

In some of the low^er animals, extirpation of the spleen
has been observed to be followed by a marked increase in
the appetite ; 1 but this effect is by no means constant, and
it sometimes follows removal of one kidney, an operation
which does not appear to interfere with any of the physiolo-
gical processes.

If food be not taken in obedience to the demands of the
system as expressed by the appetite, the sensation of hunger
becomes most distressing. It is then manifested by a pecu-
liar and indescribable sensation in the stomach, which soon
becomes developed into actual pain. This is generally ac-
companied by intense pain in the head and a feeling of
general distress, which soon render the satisfaction of this
imperative demand on the part of the system the absorbing

1 The following observation showed a very remarkable increase in the appe-
tite consequent upon the removal 0f the spleen.

Feb. II, 1861. The spleen had been removed from a young dog, the subject
of this operation, about six weeks before. The animal recovered from the opera-
tion without a bad symptom, and is perfectly well, sleek, and fat, weighing
twenty-two pounds. Since the operation, the disposition has become ferocious,
so that it is dangerous to come near him. The appetite is insatiable, and he
will eat even the refuse from the dissecting-room.

The dog was brought before the class at the New Orleans School of Medicine
at two P. M., and ate a little more than four pounds of beef-heart, or nearly one-
fifth of his weight. He had been fed abundantly about twenty-four hours be-
fore.

2

18 ALIMENTATION.

idea of existence. Starvation overcomes, in many instances,
every moral and intellectual feeling, and gives full play to
the purely animal instincts. Furious delirium frequently
supervenes after a few days of complete abstinence ; and this
is generally the immediate precursor of death. It is un-
necessary to cite any of the numerous instances in which
murder and cannibalism are resorted to when starvation is
imminent ; suffice it to say, that the extremity of hunger or of
thirst, like the sense of impending suffocation, is a demand
on the part of the system so imperative, that it must be sat-
isfied if within the range of possibility. There have been
instances of sublime resignation in the face of this terrible
agony, but these are rare in comparison with the examples
of frightful expedients to satisfy the demands of nature.

The question of the location of the sense of hunger is one
of considerable physiological interest. When we say that it
is instinctively located in the stomach, it is simply express-
ing the fact that the sensation is of a nature to demand the
introduction of food into the alimentary canal. The sense
of want of air demands the introduction of fresh air into the
lungs ; but, though air be inspired, if any thing interfere with
its passage to the system by the blood, the demand for oxy-
gen is unsatisfied. It has been shown that the real seat of
the respiratory sense is in the general system, and that this
is referred to the lungs because, necessarily, it is by the in-
troduction of air into these organs that the want is met.
This fact can be readily proven, as the effects of deprivation
of oxygen are almost instantaneously manifested. It is
easy to introduce air artificially into the lungs, and by
simply interrupting the circulation, or by draining the sys-
tem of blood, to prevent its access to the system. The same
principle is manifested, in a manner no less distinct, with
regard to the ingestion and assimilation of food. When the
system is suffering from defective nutrition, as after pro-
longed abstinence or during recovery from diseases which have
been accompanied by lack of assimilation, the mere filling

HUNGEK AND THIRST. 19

of the stomach produces a sensation of repletion of this
organ, but the sense of hunger is not relieved ; but if, on
the other hand, the nutrition be active and sufficient, the
stomach is frequently entirely empty for a considerable
time without the development of the sense of hunger. The
following observation bears strongly on this point : In a dog
with a fistula into the gall-bladder, the bile-duct having
been tied and partly exsected, digestion was so much in-
terfered with that death from inanition took place in thirty-
eight days ; and although the animal took food abundantly,
the appetite was voracious and never satisfied.1 The same
phenomenon has sometimes been observed in cases of diabetes
accompanied with great deficiency of assimilation. The ap-
petite is preserved and hunger is felt by persons who suffer
from extensive organic disease of the stomach, and the sen-
sation has been occasionally relieved by nutritious enemata
or by injections into the veins.

An interesting and curious case has lately been reported
by Prof. Busch, of Bonn, which points almost conclusively
to want of assimilation of nutritive matter by the general
system as the great cause of the sensation of hunger. In
this case, which will be more fully detailed hereafter, there
was a fistula into what appeared to be the upper third of the
small intestine. The patient was a woman, thirty-one years
of age, in the sixth month of her fourth pregnancy, and re-
ceived the injury which resulted in the fistulous opening, by
being tossed by a bull, one of the horns penetrating the ab-
domen. She was seen by Prof. Busch six weeks after the
injury, at which time every thing taken into the stomach
passed at the upper opening of the fistula. Although the
patient took food in large quantity, she became extremely
emaciated and weak. " The patient at first had a most vo-
racious appetite ; she never felt satisfied. She continued to
eat, even when the first portions of food which she had taken

1 See an article by the author, on a New Excretory Function of the Liver.
— American Journal of the Medical Sciences, Oct., 1862.

20 ALIMENTATION.

were escaping through, the opening. She would then say
that she felt better, but was still hungry. Prof. Busch infers
that hunger is composed of two separate sensations — one
general, the other local ; the former resulting from the want
of material to supply the waste of tissue." 3

These facts render it certain that the appetite and the sense
of hunger are expressions of a general want on the part of
the system, referred by our sensations to the stomach, but
really located in the general system. This want can only
be completely satisfied by the absorption of digested ali-
mentary matter by the blood and its assimilation by the
tissues. This is so evident, with our present knowledge,
that it is unnecessary to discuss the various theories which
have been proposed to account for the sense of hunger ;
such as repletion of the tubes of the stomach with gastric
juice, the reflux of bile from the duodenum, rubbing together
of the walls of the stomach, etc., etc.

The sense of hunger is undoubtedly appreciated by the
cerebrum, and it has been a question whether there be any
special nerves which have the function of conveying this
impression to the great nervous centre. The nerve which
would naturally be suspected to possess this function is the
pneumo-gastric ; but in spite of certain observations to the
contrary, it has been proven that section of both of these
nerves by no means abolishes the desire for food.2 Longet
has observed that dogs eat, apparently with satisfaction, after
section of the glosso-pharyngeal and lingual nerves.3 The
last-named observer is of the opinion that the sensation of
hunger is conveyed to the brain through the sympathetic sys-
tem. Although there are various considerations which render

1 BUSCH, Beitrag zur Physiolagie der Verdauungsorgane. — YIRCHOW'S Arcfiiv,
1858, S. 140 etseq. A summary of this case is also given in the American Jour-
nal of the Medical Sciences, July, 1860, p. 217, and in the North American Med-
ico-Chirurgical Review of the same date.

2 LEURET ET LASSAIGNE, Becker chcs Phyaiologiques et Chimiques pour servird
VHistoire de la Digestion, Paris, 1825, p. 211.

8 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 20.

HUNGEK AND THERST. 21

this somewhat probable, it is not apparent how it could be
demonstrated experimentally. It is undoubtedly the sympa-
thetic system of nerves which presides specially over nutri-
tion; and hunger, which depends upon deficiency of nutrition,
is certainly not conveyed to the brain by any of the cerebro-
spinal nerves.

Thirst is the special sensation which induces the ingestion
of water. In its moderate development, this is usually an
indefinite feeling, accompanied with more or less sense of
dryness and heat of the throat and fauces, and sometimes,
after the ingestion of a quantity of very dry food, by a pecu-
liar sensation referred to the stomach. There is nothing
agreeable connected with the sensation of thirst under any
circumstances ; but when it has become intense, the imme-
diate satisfaction which follows the ingestion of a liquid,
particularly water, is very great. Thirst is very much under
the influence of habit, some persons only experiencing a de-
sire to take liquids two or three times daily, while others do so
much more frequently. The sensation is also sensibly influenced
by the condition of the atmosphere, as regards moisture, by
exercise, and other circumstances which influence the dis-
charge of water from the body, particularly by the skin. A
copious loss of blood is always followed by great thirst. This
we have frequently noticed in the inferior animals. After
an operation involving hemorrhage, they nearly always drink
with avidity as soon as released. In diseases which are
characterized by increased discharge of liquids, thirst is gen-
erally excessive.

The demand on the part of the system for water is much
more imperative than for solids ; in this respect being only
second to the demand for oxygen. Animals will live much
longer deprived of solid food, but allowed to drink freely,
than if deprived of both food and drink.1 A man, supplied

1 It is a well-known fact that in inanition, the ingestion of water prolongs life,
in man and in the mammalia ; but the observations of Chossat have shown that

22 ALIMENTATION.

with dry food, but deprived of water, will not survive beyond
a few days. Water is necessary to the function of nutrition,
and acts, moreover, as a solvent in removing from the system
the products of destructive assimilation.

After deprivation of water for a considerable time, the
intense thirst becomes most agonizing. The dryness and
heat of the throat and fauces are increased, and accompanied
by a distressing sense of constriction. A general febrile
condition supervenes, the blood is diminished in quantity
and becomes thickened, the urine is scanty and scalding, and
there seems to be a condition of the principal viscera ap-
proaching inflammation. Death takes place in a few days,
generally preceded by delirium.

The sensation of thirst is instinctively referred to the
mouth, throat, and fauces ; but it is not necessarily appeased
by the passage of water over these parts, and it may be
effectually relieved by the introduction of water into the
system by other channels, as by injecting it into the veins.
Bernard has demonstrated by the following experiment that
water must be absorbed before the demands of the system
can be satisfied: He made an opening into the oesopha-
gus of a horse, tied the lower portion, and allowed the
animal to drink, after he had been deprived of water for a
number of hours. The animal drank an immense quantity,
but the water did not pass into the stomach, and the thirst
was not relieved. He modified this experiment by causing
dogs to drink with a fistulous opening into the stomach by
which the water was immediately discharged. They contin-
ued to drink without being satisfied, until the fistula was
closed and the water could be absorbed.1 We have often
repeated the latter experiment in public demonstrations. In

this does not take place in birds, in which starvation seems to take away the
desire for drink (CnossAT, Recherches Experimentales sur I* Inanition, Paris, 1843,
p. 59).

1 BERNARD, Legons de Physiologic Experimentale, cours de semestre cTete} Paris,
1856, p. 61.

23

---• £

one of these, particularly, the animal drank repeatedly until
he had taken several quarts of water, only ceasing from
fatigue, and soon recommencing • but as soon as the fistula
was closed, he drank a moderate quantity and was satis-
fied.

In a case reported by Dr. Gairdner, of Edinburgh, in the
human subject, all the liquids swallowed passed out at a
wound in the neck by which the oesophagus was cut across.
The thirst in this case was insatiable, though buckets-full of
water were taken in the day ; but on injecting water, mixed
with a little spirit, into the stomach, the sensation was soon
relieved.1 This observation was made in 1820, long before
the experiments just referred to upon the inferior animals.

Though the sensation of thirst is located in special parts,
it is an expression of the want of fluids in the system, and is
only to be effectually relieved by the absorption of fluids by
the blood. There are no nerves belonging to the cerebro-
spinal system which have the office of carrying this sensation
to the brain, division of which will abolish the desire for
liquids. Experiments show that no effectual relief of the
sensation is afforded by simply moistening the parts to which
the heat and dryness are referred. As a demand on the part
of the system, it is entirely analogous to the sense of want of
air and of hunger, only differing in the way in which it is
manifested.

Inanition and Insufficient Alimentation.

The history of inanition belongs more to pathology than
to physiology. To make use of the striking and oft-re-
peated quotation from the admirable monograph of Chos-
sat, it is " a cause of death which advances in the front and
in silence in every disease in which alimentation is not in a

1 GAIRDNER, Case of a Wound of the Throat in which the Trachea and (Esoph-
agus were divided across, and which did not terminate fatally, although the parts
Jiave not reunited. — Edinburgh Medical and Surgical Journal, 1820, vol. xvi.,
p. 355.

2 ALIMENTATION.

I

normal condition."1 Though inanition is a pathological
condition, it represents physiological waste of the organ-
ism without the supply of material from without by which
the tissues are regenerated. The phenomena which accom-
pany complete deprivation of nutritive material are likewise
present, in a degree, in insufficient alimentation. The termi-
nation is the same, and occurs when the system has been
reduced to the same condition as when death occurs from
absolute innutrition ; the only difference being in the inten-
sity and duration of the phenomena which precede the fatal
result. If aliment be insufficient in quantity, improper in
quality, or if the process of digestion and assimilation be so
far interfered with as to prevent the normal regeneration of
the blood, and through the blood, of the tissues, death takes
place from inanition, with phenomena identical with those
which occur in animals entirely deprived of food. The vital
properties of the tissues demand that material, of the proper
constitution and in adequate quantity, be introduced from
without. A deficiency in quantity or in quality, within
certain limits, is met by a diminished capacity on the part
of the system for that exercise, both mental and physical,
which increases waste ; and consequently, the general condi-
tion of the organism is lowered, to enable it to adapt itself to
the diminished supply. Nature can generally dispose of an
excess of nutritive material, but cannot make up a deficiency.
If, however, the quantity or quality of food be reduced be-
low a certain point, the waste must become greater than the
supply, and death takes place from inanition, more slowly,
but no less certainly, than when the nutritive supply is cut
off altogether.

Observations on the inferior animals, and the human
subject on those occasions which have presented themselves
in shipwreck, times of famine, etc., have led to a tolerably

1 CHOSSAT, Recherches Experimentales sur V Inanition, Paris, 1843, p. 194.
The term inanitialion is used by Chossat to express the progressive conditior
which results in inanition.

INAOTTION. 25

accurate knowledge of the phenomena which attend inani-
tion or insufficient alimentation. The experiments of Collard
de Martigny, on dogs, though undertaken with the view of
determining the influence of starvation on the constitution
of the blood and lymph, developed many interesting facts
with regard to the general changes which take place in this
condition.1 A few years later, the phenomena of inanition
and its influence upon the various organs were minutely
studied by Chossat, whose exhaustive memoir received the
prize of experimental physiology from the Parisian Academy
of Sciences, in 1844. These researches, beside confirming
the observations of Collard de Martigny, developed many
new facts, and have since served as the basis of our accurate
experimental knowledge on this subject.2 Phenomena anal-
ogous to those observed in animals have been noted in the
instances in which starvation has been observed in the
human subject, with the addition of certain intellectual dis-
turbances which accompany this condition.

The following are the effects of inanition, as ascertained
chiefly by experiments upon the inferior animals :

Progressive diminution in the weight of the body has
been invariably observed. Though the sensible excretions
are very much diminished in quantity, it is none the less
evident that destructive assimilation is constantly going on,
even long after the process of repair has ceased. Chossat
has shown that the maximum of daily loss of weight is
generally at the commencement of an experiment. Some-
times it is toward the termination, but never during the in-
termediate period. The great loss in weight generally ob-
served at the commencement is due to the discharge of the
residue of aliment taken the day before. Without noting
the first day, the daily loss from the commencement to the

1 COLLARD DE MARTIGNY, Recherches Experimentales sur les Effete de I1 Absti-
nence complete d'Alimem solides el liguides, sur la composition et la quantite du
Sang et de la LympJie. — Journal de Physiologic, 1828, tome via., p. 152.

2 CHOSSAT, Recherches Experimentales sur V Inanition, Paris, 1843.

26 ALIMENTATION.

fatal termination does not present any considerable variation.
The minimum loss of weight is never at the commencement,
but generally at the middle of an experiment.1 The same
observer noted that the proportionate loss of weight was
remarkably uniform, even in different classes of animals.
In experiments made upon birds, Guinea-pigs, and rab-
bits, the almost uniform result was death when the loss
reached had four-tenths of the original weight.2 This rule
is somewhat modified by obesity, under this condition the
loss of fat beyond the usual quantity being added to the
ordinary loss of four-tenths. In a few instances .the pro-
portionate loss was increased so as to amount to five-tenths
of the weight, but this appeared to be the limit. By refer-
ence to the table,3 it is seen that the two pigeons which the
author specially alludes to as very fat, and in which the loss
was over five-tenths of the weight, lived respectively lO^oV
and 20TVo- days ; the average duration of life in the animals
of this class being a little more than ten days. This would
indicate that, other things being equal, obesity gives a some-
wThat increased power of resistance to inanition.

Age seems to have a more marked and important influ-
ence upon the power of resistance to inanition and the pro-
portionate loss of weight before death occurs, than any other
circumstance. In a number of experiments upon turtle-
doves, in which they were divided into three classes : 1, the
young ; 2, those of medium age ; and 3, the adult, the
following results were obtained :

In the first class, death took place in Sy^- days, after a
proportionate loss of weight of •££$ ; in the second, death oc-
cured in ByW days, after a proportionate loss of T3o^- ; and

1 CROSS AT, op. dt., p. 16.

2 In the observations of Chossat on some of the cold-blooded animals (rep-
tiles and fishes), it was found that though life continued for a very long period —
an average of 226 days — death occurred when the loss of weight had reached
the point at which it takes place in warm-blooded animals. — (Op. dt., p. 46.)

3 Op. dt., p. 12.

INANITION. 27

in the last class, death occurred in 13T%- days, after pro-
portionate loss of -rVft-1

This corresponds with all recorded observations concern-
ing the influence of age on the power of resistance to inani-
tion, in the human subject, as well as in the inferior animals.
During the earlier periods of life, especially before the sys-
tem has attained its perfect development, aliment is de-
manded, not only to repair waste, but for growth ; and at
this time, when the demand for food is greatest, the organism
is least able to bear total deprivation, insufficient quantity,
or inferior quality of food.

All parts of the organism are by no means equally
affected by inanition. As an invariable rule, the fat dis-
appears almost completely. The blood is diminished about
three-quarters, and the digestive organs more than one-half.
The muscular system is diminished nearly one-half. The
weight of the nervous system is least affected.

The following table gives the proportionate loss of the
different parts of the body : 2

Loss per 100 of different parts of the Body in Incmition.

Parts that lose more than the mean, •fg. Parts that lose less than the mean, T%.

Fat 0-933

Blood 0-750

Spleen , 0-714

Pancreas 0-641

Liver 0-520

Heart 0-448

Intestines 0-424

Muscles of locomotion 0*423

Stomach 0-397

Pharynx, oesophagus 0'342

Skin 0-333

Kidneys 0-319

Respiratory apparatus 0-222

Osseous system 0-167

Eyes 0-100

Nervous system 0-019

After death the stomach is found small and contracted,
the intestinal canal is reduced in calibre, and its length is
diminished nearly one-third (-&%). The digestive fluids,
which are only secreted when food is contained in the ali-

CHOSSAT, op. cit., p. 28. 3 Ibid., p. 92.

28 ALIMENTATION.

mentary canal, are necessarily absent ; but the bile, which
is an excretion as well as a secretion, is still found in the
gall-bladder, but is apparently concentrated. In some of
the observations of Collard de Martigny, urine was found in
the bladder, but it contained no urea. Lassaigne found urea
in the urine of an insane person who had not eaten for eigh-
teen days.1

The faeces are discharged infrequently, and are scanty and
hard, except in certain cases when diarrhoea sets in toward
the close of life. Diarrhoea was noted, occurring at this
time, in some of the observations of Chossat.

One of the most marked and important changes in inani-
tion is diminution in quantity and impoverishment of the
blood. Collard de Martigny observed the quantity of blood to
undergo diminution to such an extent that the skin and some
of the muscles, when incised, discharged no blood, but only a
little serum, sometimes colorless and sometimes slightly rose-
colored. He is of the opinion that during the later periods of
inanition, many of the tissues receive no blood.2 It is evident
that when the quantity of blood has become so much reduced,
the process of nutrition in many parts must be nearly abol-
ished.

The general effect of inanition upon the circulation is to
diminish the force and frequency of the heart's action, ex-
cept during the cerebral excitation, which is so frequent
during the early periods of starvation. The heart becomes
very much atrophied, being reduced in weight nearly one-
half. In a man convicted of murder and condemned to
death, who allowed himself to die of starvation, taking noth-
ing but water for sixty-three days, the pulse descended to thir-
ty-seven beats per minute.3

After a certain period of complete abstinence, it is im-
possible to restore the powers of life by the administration

1 COLLARD DE MARTIGNY, op. cit., p. 157.

a Ibid., p. 168.

8 BERARD, Cours de Physiologic, Paris, 1848, tome i., p. 529.

INANITION. 29

of food. This has been observed in persons rescued from
immediate starvation, who, in the last stages, can only be
temporarily revived. Magendie, in experimenting upon the
nutritive powers of different articles of food, observed in a
dog that had been fed exclusively on butter, all the phenom-
ena which accompany inanition. This animal died of starva-
tion on the thirty-sixth day, although on the thirty-second
day he was given an abundance of meat, which he continued
to eat for two days.1

The effect of inanition on respiration is to gradually di-
minish the number of respiratory acts, except during the
stages of cerebral, excitation, and, according to Chossat,
near the fatal termination, when the respiration is some-
times panting. The exhalation of carbonic acid is gradually
and progressively diminished. In an observation by Bidder
and Schmidt on a cat, the exhalation of carbonic acid was
gradually diminished, until just before the death of the ani-
mal (eighteen days), it was reduced a little more than one
half.2 After a few days of complete inanition, or in persons
who have been subjected for some time to insufficient ali-
mentation, the breath becomes insufferably fetid and offen-
sive. In the instance reported by Dr. Soviche of eight men
who were shut up in a coal mine for nearly six days, with
but a half-pound of bread, a bit of cheese, and two glasses of
wine, the offensive character of the pulmonary exhalations
was one of the greatest sources of suffering.3

The influence of progressive inanition upon the animal
temperature is very marked. The organism seems to lose
the power of maintaining that uniform temperature which
is peculiar to warm-blooded animals. In almost all in-
stances of inanition in the human subject, a considerable

1 MAGENDIE, Precis filementaire de Physiologic, Paris, 1836, tome ii., p. 502.

2 See vol. i., Respiration, p. 434.

3 SOVICHE, Exlrait du Rapport sur les Jiuit Hineurs enfermes pendent cent
(rente-six hcures dans la Houillicre du bois Monzil. — Journal des Connaissances
Medico- Chirurgicales, Paris, 1836-1837, tome iv., p. 119.

30 ALIMENTATION.

diminution in temperature has been noted. In the case of
the murderer already referred to,1 the temperature was low-
ered to Y5° Fahr. The observations of Chossat on this sub-
ject are very exact and satisfactory. He commenced by
noting the average normal temperature of the animals to
be experimented upon, with the variations at different times
of the day. In pigeons he found that the maximum of tem-
perature (108°) occurred at mid-day ; the minimum, at mid-
night, was 106°.66, giving an extreme variation of 1°.34:
Fahr. This variation was independent of the surrounding tem-
perature. During the progress of inanition, the daily vari-
ation was increased to 5°.9.2 There was also a very slight,
but well-marked diminution in the absolute temperature.
It was found, also, that the animals recovered from the dimi-
nution in temperature which occurred at night with more
difficulty than during normal alimentation, and the periods
of minimum temperature were unusually prolonged.

All these facts point to a progressively diminished capa-
city of maintaining the independent temperature of the
body during inanition. Immediately preceding the fatal
termination, the diminution in temperature became very
rapid, the rate, in the observations on turtle-doves, being
from 7° to 11° per hour. Death usually occurred when the
diminution had amounted to about 30°.3

1 See p. 28.

2 Op. cit, p. 123.

3 The experiments of Chossat on the effects of artificial warmth on animals in
the last stages of inanition, when the temperature had been reduced nearly to the
point at which death occurs, are of great interest. In some of the animals, artificial
heat, with food, restored the vital powers so that they were able to digest the food,
the muscular power returned, and they finally recovered. In nearly all, even after
the inanition had proceeded so far that muscular power was entirely lost and death
was imminent, partial restoration was accomplished. They generally moved about
with animation, were able in some instances to fly, took food when it was pre-
sented to them, and digested it, though this process took place more slowly than
in health. Digestion, however, did not continue when the artificial warmth was
suspended. The heat thus acquired was found to be easily lost, and did not pre-
sent that degree of uniformity which characterizes the normal animal tempera-

INANITION. 31

After a certain period of inanition, febrile movement and
general agitation occur ; and there is almost always disturb-
ance of the mental faculties, amounting sometimes to furious
delirium. Frequently, however, the delirium is of a mild
character, with hallucinations. There are cases in which
there is no marked mental disturbance, but these are gen-
erally in persons who voluntarily suffer starvation. In a dog
experimented upon by Collard de Martigny, which died on the
thirty-fifth day, from the eleventh to the nineteenth day the
animal was in a furious condition, gnawing almost constantly
at the bars of the cage. This was followed by a condition of
great debility, which continued, with short periods of agita-
tion, until death. During inanition, both in man and in the
inferior animals, there is very little sleep.

The length of time that life continues after complete
deprivation of food and drink is very variable. The influ-
ences of age and obesity have already been referred to.
Without citing the numerous individual instances of starva-
tion in the human subject which have been reported, it may
be stated in general terms, that death occurs after from five
to eight days of total deprivation of food. In 1816, one
hundred and fifty persons, wrecked on the frigate Medusa/
were exposed on a raft in the open sea for thirteen days.
At the end of this time only fifteen were found alive. One
of the survivors, M. Savigny, gave, in an inaugural thesis,
a very instructive and accurate account of this occurrence,
which has been very generally quoted in works of physiol-
ogy. Authentic instances are on record where life has been
prolonged much beyond the period above mentioned; but
they generally occurred in persons who were so situated as
not to suffer from cold, which the system under this condi-
tion has very little power to resist. In these cases, also,
there was no muscular exertion, and water was generally

ture. For a full discussion of these interesting questions, the reader is referred
to the work of Chossat, p. 155 et aeq.

32 ALIMENTATION.

taken in abundance.1 All of these circumstances have an
important influence in prolonging life.

Berard quotes the example of a convict who died of star-
vation after sixty-three days, but in this case water was
taken. The instance of eight miners who survived after five
days and sixteen hours of almost complete deprivation of food
has already been referred to. Berard also quotes from various
authorities instances of deprivation of food for periods vary-
ing from four months to sixteen years. All of the subjects
were females, and the histories of such cases, reports of which
are by no means uncommon, belong properly to psychology ;
as they are undoubtedly examples of that morbid desire to
excite sympathy and interest which is sometimes observed,
and which leads to the most adroit and persevering efforts at
deception.2

The observations of Chossat on the duration of life in
inanition show great variations in the different classes of
animals. In experiments on -birds, chiefly turtle-doves and
pigeons, death occurred, on an average, after 9^0- days of
complete deprivation of food and drink. In Guinea-pigs
and rabbits, the same observer noticed an average duration
of 9-^o9Q- days.3 It has generally been noticed that life is more
prolonged in carnivorous than in herbivorous animals. In

1 In the Social Science Review and Journal of Sciences, London, edited by
Dr. B. M. Richardson, we find the following note : " We ourselves knew an in-
stance in which a man with a disordered mind refused all food for thirty days ;
after a short return to food, again refused for thirty-six days. But in this in-
stance, on the second occasion, the sufferer died, although he had recommenced
to swallow light nourishment. Ed." (1864, vol. i., New Series, p. 180.)

2 From time immemorial the credulous have periodically been startled with
reports of wonderful cases in which persons (generally females) have li ved for an
incredible time without food. A curious specimen of these histories is an ac-
count of the case of a girl, ten years of age, who lived without food and drink,
and in whom development, &c., seemed to be normal. This was testified to by a
learned physician, in 1542. (De puella, quce sine cibo et potu vitam tramigil,
brcvis narratio, teste et auctore GERARDO BUCOLDIANO PHYSICO REGIO, Parisiis,
Ex officina Rob. Stephani typographi Regii, M.D.XLII. Cum privilegio Regis.)

8 Op. tit., p. 31.

INANITION. 33

one of the dogs experimented upon by Collard de Martigny,
death occurred on the thirty-fifth day, and, in another, on
the twenty-seventh day. The average duration of life in
rabbits was from ten to twelve days.1 Leuret and Lassaigne
observed that dogs, kept in a warm and dry place, lived, on
an average, thirty days without food or drink. A dog that
was kept in a dark and damp place lived for forty days.2
From thirty to thirty-five days, therefore, may be taken as
the average duration of life in dogs deprived entirely of food
and drink. This fact it is important to bear in mind in con-
nection with observations on the nutritive value of different
articles of food.

Chossat states, as the result of his observations, that the
duration of life in inanition being equal to the total loss of
weight divided by the average daily loss, in adult animals it
is equal to -f-f^ of the weight of the body divided by the av-
erage daily loss.3 This formula is highly important in a
practical point of view ; for, in conditions of the system in
which inanition is threatened, it is easy to estimate the prob-
able duration of life (if we fear that death may occur from
inanition alone), by dividing the total loss of weight which
will probably produce death, by the average daily loss ; and
anything which will diminish the average daily loss, we ma}-
reasonably suppose will retard the fatal termination.

Insufficient Alimentation. — When alimentation is re-
duced below the standard at which life can be maintained,
whether it be from diminished quantity or improper quality of
food, the phenomena are very much like those which follow
complete abstinence ; and, curiously enough, experiments on
animals have shown that death takes place when the weight
is reduced by about the same proportion as in absolute in-

1 Loc. cit.

a LEURET ET LASSAIGNE. Recherches Physiologiques et Chimiques pour servir
d VHistoire de la Digestion. Paris, 1825, p. 210.
3 CHOSSAT, op. cit., p. 34.
3

34: ALIMENTATION.

nutrition. Under these circumstances, the amount of food
which is taken diminishes, more or less, the proportionate
daily loss of weight, and thus retards the fatal result.

The effects of insufficient alimentation in man have often
"been observed in times of famine ; the sad details of which
have been given in graphic accounts by various European
writers. The history of our own country during the late civil
war affords an example, the most appalling on record in any
country and in any age, of the sufferings of thirty thousand
men exposed within an area of twenty-seven acres to the ef-
fects of insufficient diet, conjoined with exposure, without
protection, to the vicissitudes of the weather, and the frightful
filth and other inevitable results of such excessive crowding.

In a report by Prof. Ellerslie Wallace, of Philadelphia,
to Prof. Valentine Mott, the chairman of a committee ap-
pointed by the United States Sanitary Commission to in-
quire into the condition of United States officers and soldiers,
prisoners of war, the following is given as the average diet
in Southern prisons :

" The meat was irregularly given ; not often daily, and
to some only at intervals of days, or even several weeks, and
when meat was served, the bread was, in many instances,
diminished.

" About half a pint of soup, containing sweet potatoes, or
generally beans or peas, in amount about two ounces, was
sometimes given, with or without meat in different cases.
The beans and peas were occasionally given raw and dry.

" The maximum amount of solid food for one day, de-
scribed, was 10 oz. bread.

6 oz. beef.

" "With half a pint of soup made of the wa-
ter in which the beef was boiled, and contain-
ing about two ounces of beans or peas, and
therefore representing . . . . 2 oz.

"Total, . . 18 oz.

INAOTTION. 35

" The minimum amount was about . . 4 oz. bread.

«'• 1 oz. beef.

"Total, ., . 5oz."]

Assuming the amount of solid food required to keep the
system of an adult male in proper condition to be from thirty
to forty ounces, it is seen that even the maximum amount
above given is so far insufficient for the purposes of nutri-
tion, that death from inanition must result, sooner or later,
in the majority of instances. This is assuming that the food
be of proper quality; while the testimony taken by the
commission showed that the quality was always inferior,
generally disgusting, and that no variety of diet was af-
forded.

The effects of insufficient food upon the power of resist-
ing cold was one of the most marked phenomena. Even in
the mild climate of the South, frost-bite and gangrene of the
extremities were very frequent. These occasional results,
taken in connection with the extreme emaciation, the pecu-
liar mental condition, etc., which go to make up the general
aspect of inanition, presented a picture more distressing than
can well be imagined. The description by De Meersman of
the famine in Belgium in 1846 and '47, though it may seem

1 Narration of Privations and Sufferings of United States Officers and Sol-
diers while Prisoners of War in the hands of the Rebel Authorities. Being the
Report of a Commission of Inquiry, appointed by the United States Sanitary
Commission. With an Appendix containing the Testimony. Philadelphia, 1864,
p. 111.

The commission consisted of Valentine Mott, M. D., LL. D., Edward Delafield,
M. D., Gouverneur Morris Wilkins, Esq., Ellerslie Wallace, M. D., Hon. J. I. Clark
Hare, and Rev. Treadwell Wai den. The statement quoted from the report of
Dr. Wallace was corroborated by the sworn testimony of numerous officers and
men who had been prisoners of war, and the facts were admitted by many of the
public authorities directly or indirectly in charge of the prisoners, so that there
can be no doubt of their general accuracy. (See reports and testimony of sur-
geons and others in charge of prisoners, in the trial of Henry Wirtz.)

36 ALIMENTATION.

highly colored, must, judging from the experience in this
country, even fall short of the reality.1

" What was striking in the first place," says De Meers-
man, " during the famine mentioned above, was the extreme
emaciation of the body, the livid pallor of the countenance,
the hollow cheeks, and, above all, the expression of the eye,
of which one could not lose the remembrance when it was
once seen. There was, indeed, a strange fascination in that
eye, in which all the vitality of the individual seemed to be
contained, which glitters with a feverish light; the pupil,
enormously dilated, is fixed upon you without winking, and
with an interrogative astonishment, in which kindliness is
mingled with fear. The movements of the body are slow ;
the gait is uncertain ; the hand trembles ; the voice, almost
extinct, is tremulous. The intelligence is profoundly affect-
ed ; answers are painful ; memory, in the majority, is almost
lost. Interrogated concerning the sufferings they endure,
these unfortunates answer that they do not suffer, but that
they are hungry !

" The breath is extremely fetid ; the tongue thin, pointed,
elongated, tremulous, almost always red ; the point, often
aphthous, is covered with a yellowish and opaque coating ;
the epigastrium is retracted, and the skin in that region is, so
to speak, drawn to the vertebral column ; it sometimes hap-
pens that the epigastrium is distended by meteorism ; the
touch then discovers organic engorgements in one part and
another of the abdomen. Respiration is slow*, not deep, and
often interrupted by sighs. The pulse, sometimes very fre-
quent, sometimes remarkably slow, is easily compressed, of
astonishing smallness, and disappears under the finger. The
secretions are all affected by the alterations in the blood,
which is their common source ; but above all, the perspira-
tion, which is greatly modified. The skin was dry, yellow,

1 Dr. Wallace (loc. cit.) alludes to the description of De Meersman as giving
a " singularly accurate description " of the condition of exchanged United States
soldiers.

INANITION. 37

resembling parchment; the exhalation, which in the ordi-
nary condition takes place insensibly from the entire surface,
is effected in this case in a dry way. The pores of the skin
gave out a viscid powder, which, accumulating and becoming
concreted, covered the body with a blackish crust, pulveru-
lent and horribly fetid." l

To these phenomena may be added occasional perfora-
tion of the cornea, scorbutus in its various forms, gangrena
oris, particularly in children, disturbances of the menstrual
function, and abortion. The number of births has always
been observed to be very small in communities suffering
from insufficiency of food.

Through the kindness of Prof. "W. H. Yan Buren, of the
United States Sanitary Commission, we have been enabled
to make use of a MS. report to the Richmond authorities
(now the property of the Commission) on the condition of
United States soldiers, prisoners of war at Andersonville, by
Prof. Joseph Jones, of Augusta, Georgia.2 Dr. Jones is well
known to the profession as the author of several physio-
logical papers of interest published in the " American Jour-
nal of Medical Sciences," and by the Smithsonian Institute.
From a perusal of this report, and from the scientific position
and ability of its author, we are convinced that it is an ac-
curate and careful statement of facts observed by one who
had every opportunity and facility for full investigation.
Though the investigations were made chiefly with reference
to the diseases which prevailed among these unfortunate
men, as regards many physiological points, it is the most

1 DE MEERSMAN, in LONGET, Traite de Physiologic. Paris, 1861, tome i.,
p. 25.

9 Investigations upon the Diseases of the Federal Prisoners confined in Camp
Sumpter, Andersonville, Ga., instituted with a view to illustrate chief,}/ the Origin
and Causes of Hospital Gangrene, the Relations of Continued and Malarial Fe-
vers, and the Pathology of Camp Diarrhoea and Dysentery. By JOSEPH JONES,
M. D., Professor, of Medical Chemistry in the Medical College of Georgia, at Au-
gusta, and formerly Surgeon in the Provisional Army of the Confederate States ;
in three volumes, Manuscript. Augusta, Ga., 1865-'66.

38 ALIMENTATION".

complete scientific history of inanition ever written, deduced
from data which are, and probably always will be, unpar-
alleled in magnitude. The pathological questions will be
fully considered in one of the volumes on the Medical and
Surgical History of the Rebellion, now in course of prep-
aration under the direction of the Commission ; and in this
connection, will be considered, generally in the author's own
words, the points which bear mainly on the effects of insuf-
ficient alimentation, though the other circumstances under
which the prisoners were placed must necessarily be taken
into account.

The following extract from an official report by Dr.
Jones, dated October 19, 1864, gives an idea of the sanitary
condition under which the prisoners were placed :

" Immediately after the brief report upon hospital gan-
grene had been forwarded to the surgeon-general, I re-
paired to Camp Sumpter, Andersonville, Georgia, and insti-
tuted a series of investigations upon the diseases of the
Federal prisoners.

" The field was of great extent and of extraordinary in-
terest. There were more than five thousand (5,000) seriously
sick in the hospital and stockade, and the deaths ranged
from ninety to one hundred and thirty each day. Since the
establishment of this prison, on the 24th of February, 1864,
to the present time, over ten thousand Federal prisoners have
died : that is, near one-third of the entire number have per-
ished in less than seven months. I instituted careful investi-
gations into the condition of the sick and well, and per-
formed numerous post-mortem examinations, and -executed
drawings of the diseased strictures. The medical topography
of Andersonville and the surrounding country was exam-
ined, and the waters of the streams, springs, and wells
around and within the stockade and hospital carefully
analyzed.

" Diarrhosa, dysentery, scurvy, and hospital gangrene
were the diseases which have been the main causes of the

INANITION. 39

extraordinary mortality. The origin and causes of the hos-
pital gangrene which prevailed to so remarkable a degree,
and with such fatal effects amongst the Federal prisoners,
engaged my most serious and earnest consideration. More
than thirty thousand men crowded upon twenty-seven acres
of land, with little or no shelter from the intense heat of a
Southern summer, or from the rain and dew, with coarse
corn-bread from which the husk had not been removed, with
scant supplies of fresh meat and vegetables, with little or no
attention to hygiene, with festering masses of filth at the
very doors of their rude dens and huts, with the greater por-
tion of the banks of the stream flowing through the stock-
ade a filthy quagmire of human excrements alive with work-
ing maggots: — generating by their own filthy exhalations
and excretions an atmosphere that so deteriorated and con-
taminated their solids and fluids, that the slightest scratch
of the surface, even the bites of small insects, were fre-
quently followed by such rapid and extensive gangrene, as
to destroy extremities and even life itself. A large number
of operations have been performed in the hospital on account
of gangrene following slight injuries and mere abrasions of
the surface. In almost every case of amputation for gan-
grene, the disease returned, and a large proportion of the
cases have terminated fatally. I recorded careful observa-
tions upon the origin and progress of these cases of gan-
grene, and examined the bodies after death, and noted
the pathological changes of the organs and tissues. All
these observations, together with the drawings, will be
forwarded to the surgeon-general, at the earliest possible
moment." '

In vol. i.? p. 213, Dr. Jones gives the ration of the pris-
oners. This was probably the regular ration, which was
undoubtedly lessened at times, for the evidence taken by
the committee appointed to investigate the condition of

1 Report, vol. i., Preface, pp. 12, 13.

40 ALIMENTATION.

•

exchanged prisoners shows that the average was much
less.1

" 5^A, Diet. — The ration consists of Jib. bacon, l{lb. meal.
The meal is unbolted, and when baked, the bread is coarse
and irritating, producing diseases of the organs of the diges-
tive system (diarrhoea and dysentery). The absence of ve-
getable diet has produced scurvy to an alarming extent,
especially among the old prisoners."

The following extracts show the effects of this insufficient
diet upon the constitution of the blood, upon the appetite,
and, what is most mournfully interesting, upon the intellec-
tual faculties :

" 5tk. From the sameness of the food and from the action
of the poisonous gases in the densely crowded and filthy stock-
ade and hospital, the /blood was altered in its constitution^
even before the manifestation of Actual disease.

" In both the well and the sick, the red corpuscles were
diminished ; and in all diseases uncomplicated with inflam-
mation, the fibrinous element was deficient. In cases of ulcer-
ation of the mucous membrane of the intestinal canal, the
fibrinous element of the blood appeared to be increased, whilst
in simple diarrhoea, uncomplicated with ulceration, and de-
pendent upon the character of the food, and the existence
of scurvy, it was either diminished or remained stationary.
Heart-clots were very common, if not universally present, in
the cases of ulceration of the intestinal mucous membrane,
whilst in the uncomplicated cases of diarrhoea and scurvy,
the blood was fluid and did not coagulate readily ; and the
heart-clots and fibrinous concretions were almost universally
absent.

" From the watery condition of the blood, there resulted
various serous effusions, into the pericardium, into the ventri-
cles of the brain, and into the abdominal cavity.

" In almost all the cases which I examined after death,

INANITION. 41

even in the most emaciated, there was more or less serous
effusion into the abdominal cavity." * * * — (Vol. iii., p.
150.)

" §th. The impoverished condition of the blood, which
led to effusions within the ventricles of the brain, and
around the brain and spinal cord, and into the pericardial
and abdominal cavities, was gradually induced by the
action of several causes, but chiefly by the character of the
food.

"The Federal prisoners, as a general rule, had been
reared upon wheat bread and Irish potatoes ; and the Indian
corn, so extensively used at the South, was almost unknown
to them as an article of diet, previous to their capture. Owing
to the impossibility of obtaining the necessary sieves in the
Confederacy, for the separation of the husk from the corn
meal, the rations of the Confederate soldiers as well as of the
Federal prisoners consisted of unbolted corn-flour, and meal,
and grist; this circumstance rendered the corn bread still
more disagreeable and distasteful to the Federal prisoners.
Whilst Indian meal, even when prepared with the husk, is
one of the most wholesome and nutritious forms of food, as
has been clearly shown by the health and rapid increase of
the Southern population, and especially of the negroes, pre-
vious to the present war, and by the strength, endurance,
and activity of the Confederate soldiers, who were through-
out the war confined, to a great extent, to unbolted corn-
meal ; it is nevertheless true, that those who have not been
reared upon corn meal, or who have not accustomed them-
selves to its use gradually, become excessively tired of this
kind of diet when suddenly confined to it without a due
proportion of wheat bread. Large numbers of the Federal
prisoners appeared to be utterly disgusted with Indian corn,
and immense piles of corn bread could be seen in the stock-
ade and hospital enclosures. Those who were so disgusted
with this form of food that they had no appetite to partake
of it, except in quantities insufficient to supply the waste of

42 ALIMENTATION.

the tissues, were of course in the condition of men slowly
starving, notwithstanding that the only farinaceous form of
food which the Confederate States produced in sufficient
abundance for the maintenance of armies, was not withheld
from them. In such cases an urgent feeling of hunger was
not a prominent symptom ; and even when it existed at first,
it soon disappeared, and was succeeded by an actual loathing
of food. In this state the muscular strength was rapidly
diminished, the tissues wasted, and the thin, skeleton-like
forms moved about with the appearance of utter exhaustion
and dejection. The mental condition, connected with long
confinement, with the most miserable surroundings and with
no hope for the future, also depressed all the nervous and
vital actions, and was especially active in destroying the
appetite. The effects of mental depression and of defective
nutrition were manifested not only in the slow, feeble motions
of the wasted, skeleton-like forms, but also in such lethargy,
listlessness, and torpor of the mental faculties, as rendered
these unfortunate men oblivious and indifferent to their
afflicted condition. In many cases, even of the greatest
apparent suffering and distress, instead of showing any
anxiety to communicate the causes of their distress, or to
relate their privations and their longings for their homes and
their friends and relations, they lay in a listless, lethargic,
uncomplaining state, taking no notice either of their own
distressed condition or of the gigantic mass of human mis-
ery by which they were surrounded. Nothing appalled
and depressed me so much as this silent, uncomplaining
misery.

" It is a fact of great interest that, notwithstanding this
defective nutrition in men subjected to crowding and filth,
contagious fevers were rare, and typhus fever, which is sup-
posed to be generated in just such a state of things as existed
at Andersonville, was unknown. These facts, established by
my investigations, stand in striking contrast with such a

INANITION. 43

statement as the following, by a recent English writer.1 (Vol.
iii., pp. 151-155.)

1 Dr. Jones states in another part of his report (vol. ii., p. 14), that " but a
comparatively small number of the Federal prisoners were affected with malarial
fever, and the deaths from this disease amounted to but a small fraction of the
deaths from all causes ; " and again it is stated (p. 41), that " the comparative
immunity from malarious disease among the Federal prisoners is still further
shown by the small number of cases of neuralgia entered upon the sick reports :
amongst the large body of Federal prisoners, with a mean monthly strength of
21,120, only 33 cases of neuralgia were reported during a period of six months."

CHAPTEE II

ALIMENTATION.

General considerations — Division of alimentary principles — Nitrogenized aliment-
ary principles — Masculine — Albumen — Caseine — Fibrin — Gelatine and Chon-
drine — Vegetable albumen, fibrin, and caseine — Gluten — Non-nitrogenized
alimentary principles — Sugar — Starch — Vegetable principles resembling
starch — Fats and oils — Inorganic alimentary principles — Water — Chloride of
sodium — Phosphate of lime — Iron.

UNDER the name of aliment, in its widest signification, it
is proposed to include all articles composed of, or containing
elements in a form which enables them to be used for the
nourishment of the body, either by being themselves appro-
priated by the organism, by influencing favorably the process
of nutrition, or by retarding destructive assimilation. Those
principles which are themselves appropriated may be called
direct aliments ; and those which simply assist nutrition
without contributing reparative material, together with those
which retard destructive assimilation,1 may be termed acces-
sory aliments. By this definition of aliment, nothing is ex-
cluded which contributes to nutrition. The air must be con-
sidered in this light, as well as water and all articles which
are commonly called drinks.

In the various articles used as food, nutritious elements are
frequently combined with each other and with indigestible
and non-nutritious principles. The elements of the food
which are directly used in nutrition are the real alimentary
principles, embracing, thus, only those principles which are
capable of absorption and assimilation. The ordinary food
of the warm-blooded animals contains alimentary principles,

NITEOGENIZED ALIMENTARY PKCSTCIPLES. 45

united with innutritions substances from which they are sep-
arated in digestion. This necessitates a complicated digestive
apparatus. In some of the inferior animals, the quantity of
nutritious material forms so small a part of the food, that the
digestive apparatus is even more complicated than in the
human subject. This is especially marked in the herbivora,
the flesh of which forms an important part of the diet of
man. In addition to what are distinctly recognized as ali-
mentary principles, food contains many substances having an
important influence on nutrition, which have never been iso-
lated and analyzed, but which render it agreeable and give to
the diet a variety which the system imperatively demands.
Many of these principles are developed in the process of
cooking. They will be considered, as far as practicable, in
connection with the different articles of diet.

The alimentary principles belong to the inorganic, vege-
table, and animal kingdoms, and are generally divided into
the following classes : *

1. Organic nitrogenized principles (albumen, fibrin, ca-
seine3 musculine, etc.), belonging to the animal kingdom ;
and vegetable nitrogenized principles, such as gluten and
legumine.

2. Organic non-nitrogenized principles (sugars, fats, and
starch).

3. Inorganic principles.

Nit/rogenized Alimentary Principles.

In the nutrition of certain classes of animals, these prin-
ciples are derived exclusively from the animal kingdom, and in
others, exclusively from the vegetable kingdom ; but in man,
who is omnivorous, both animals and vegetables contribute
nitrogenized material. In both animal and vegetable food,
these principles are always found combined with inorganic

1 Inorganic and animal substances have already been considered in treating
of proximate principles (see vol. i., Introduction).

46 ALIMENTATION.

matters (water, chloride of sodium, the phosphates, sulphates,
etc.), and frequently with non-nitrogenized principles (sugar,
starch, and fat).

Musculine. — Of the different nitrogenized principles used
as food, musculine, albumen, caseine, and fibrin are the most
important. Musculine, the organic principle which forms the
bulk of the muscular substance, excluding the- areolar tissue
which binds the fibres together, and the sarcolemma, is per-
haps the most important and abundant article of this class.
This substance is considered by some as identical with the
fibrin of the blood ; but it presents many points of difference
which warrant us in regarding it as a distinct principle. ' It
is always ^united with more or less inorganic matter, which
cannot be separated without incineration. The fiesh of dif-
ferent animals presents wide differences in general appear-
ance, in nutritive properties, and in flavor, which become
more marked after the formation of the odorous empyreu-
matic substances which are developed in cooking ; but the
organic principle of all of them is musculine. Muscular
tissue is rendered much more digestible by cooking — a pro-
cess which serves to disintegrate, to a certain extent, the
inter-muscular areolar tissue, and facilitate the action of the
digestive fluids. The savors developed in this process have
a decidedly favorable influence on the secretion of the gastric
juice. It is doubtful whether pure musculine would be ca-
pable of supporting life for a long period ; 1 but the muscular
tissue has been shown by experiment to be sufficient for the
purposes of nutrition, in the carnivora, and it undoubtedly is
in man.

1 In the report of the ^ Gelatine Committee " to the Institute of France, in
1841 (M. Magendie, reporter), it was shown that dogs fed on meat which had been
subjected to prolonged boiling and afterward freed from fat by being pressed
in paper, became emaciated, and would have died of inanition if the experiment
had been persisted in. But this experiment is not entirely conclusive, as much
of the nutritive principle of the musculine must have been extracted by boiling.
(Comptes Rendus, Paris, 1841, tome xiii., p. 275.)

OTTEOGENIZED ALIMENTARY PRINCIPLES. 47

Of all kinds of muscular tissue, beef possesses the greatest
nutritive power. Other varieties of flesh, even that of birds,
fishes, and animals in a wild state, do not present an ap-
preciable difference, as far as can be ascertained by chemical
analysis ; but when taken daily for a long time, they become
distasteful, the appetite fails, and the system seems to de-
mand a change of diet. The flesh of carnivorous animals is
rarely used as food ; and animals that feed upon animal as
well as vegetable food, such as pigs or ducks, acquire a dis-
agreeable flavor when the diet is not strictly vegetable.

Of the various methods which have been employed for
the preservation of meat, salting, which is the most common,
has the most unfavorable influence on its nutritive properties.
Experience has shown that salted meat is much less nutri-
tious than fresh, and the gravest effects on the nutrition of
the body have followed its prolonged use as the principal
article of diet. It has also been ascertained chemically,
that brine extracts from the muscular tissue much of its
nutritive principle.

Albumen. — This is an alimentary principle hardly second
in importance to musculine. As an article of diet, it is
chiefly found in the white of egg, where it exists in great quan-
tity, and is combined with a variety of inorganic substances.
Though an important alimentary principle, it cannot meet
all the nutritive requirements of the organism. Numerous
observations on the inferior animals, and those of Hammond
on his own person,1 have shown that pure albumen will not
sustain life. The egg of the fowl, however, containing in
addition to albumen a large quantity of inorganic mat-
ter, the fatty matter of the yolk, and other organic prin-
ciples, is a most nutritious article of food. Albumen is the

1 HAMMOND, Experimental Researches relative to the nutritive value and physi-
ological effects of Albumen, Starch, and Gum, when singly and exclusively used as
Food. — Prize Essay — Trans. American Med. Assoc., 1857, and Physiological
Memoirs, Philadelphia, 1863, p. 67.

48 ALIMENTATION.

great nutritive nitrogenized principle of the blood, and is
the substance into which all the principles of this class which
exist in food are converted before they are applied to the nu-
trition of the tissues.

Caseine. — At a certain period of life this constitutes es-
sentially the sole nitrogenized article of food. It is found only
in milk, and it exists largely in the great variety of cheeses
which are manufactured from milk. In addition to caseine,
milk contains butter, sugar, and a variety of inorganic prin-
ciples ; and is capable of supplying material for the nourish-
ment of all parts of the organism, caseine supplying the nitro-
genized principle. In the form of cheese, caseine constitutes
an important article of food.

Fibrin. — Fibrin is by no means so important an article
of diet as those just considered, and it very seldom forms any
considerable part of our food. The same may be said of
some other principles of this class, such as globuline, which
is the organic principle of the blood-corpuscles; vitelline, a
principle peculiar to the yolk of the egg ; osteine and car-
tilagine. The two latter substances are generally taken after
they have undergone peculiar modifications in cooking, when
they are known by other names.

Gelatine and Chondrine. — After prolonged boiling, the
organic principles of the bones, integuments, areolar tissue,
tendons, and other structures composed of the white fibrous
tissue, are dissolved and transformed into a new substance,
which is called gelatine. Cartilage, treated in the same
way, is in great part converted into chondrine. These two
substances are artificial products, and therefore were not
considered in treating of the proximate principles of the

anism.1

The principles thus formed are soluble in hot water,

1 See vol. i., Introduction.

NITKOGENIZED ALIMENTARY PRINCIPLES. 49

rendering it slightly viscid, but on cooling, the whole mass
becomes of a more or less gelatinous consistence, according
to the quantity of gelatine that is present. A considerable
quantity of inorganic matter, particularly phosphate of lime,
is always present in combination with gelatine.

Gelatine and chondrine present slight differences as re-
gards their chemical reactions, in other respects being nearly
identical. The sulphate of alumina, alum, and the sulphate
of iron, will precipitate chondrine, but have no influence on
a solution of gelatine. Tannin, or infusion of galls, added
to a solution of gelatine, produces a brownish precipitate.
This reaction is marked in a solution containing but one
part of gelatine to five thousand of water. Both gelatine
and chondrine are of indefinite chemical composition and
uncrystallizable.1 By the action of sulphuric acid, gelatine
is transformed into a crystallizable substance called glyco-
colle, which has a sweetish taste, is soluble in water and
insoluble in alcohol and ether. According to some, this is
capable of being separated into alcohol and carbonic acid
by fermentation.2

A great deal of interest was at one time attached to gela-
tine as an article of food, from the fact that it is formed and
extracted from parts, particularly the bones, which were
before regarded as comparatively useless. Indeed, the ex-
periment of diminishing the quantity of meat, and supplying
in its place the extract of bones, was made in several hospi-
tals and manufacturing establishments in France ; but this
change in diet led so universally to complaints of insufficien-
cy of food, that experiments were soon instituted with a view
of determining whether gelatine really possessed any nutritive
power. "Without entering upon a full discussion of these exper-

1 The formulae generally given for these two substances are: Gelatine, C18
H^OsN^j, and Chondrine, C32 H26 Oi4N4; but, as remarked by Longet, these
formulae are very uncertain. Chondrine is supposed by some (Mulder, Robin) to
contain, in addition, a little sulphur.

2 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 44, note.

4

50 ALIMENTATION.

iments, it may be stated that the introduction of gelatine as
an article of diet, to the exclusion of other principles which
were known to be nutritive, was always followed by loss of
weight and the indications of more or less defective nutri-
tion. In other words, the introduction of gelatine did not
permit any diminution in the quantity of ordinary articles
of food. The whole question was finally settled by the
researches of Magendie, the reporter of the committee on
gelatine, in 1841. This report embodied the results of
numerous experiments on the effects of various nitrogenized
principles ; but the conclusions with regard to gelatine were,
that taken alone it was distasteful in the highest degree,
even to animals on the verge of starvation ; and that even
the agreeable jelly formed of different parts of the pig and
the giblets of fowl, prepared by the charcutiers of Paris,
at first taken by the animals with apparent satisfaction, was
refused after a few days ; and when animals were confined
exclusively to this article, death took place about the twen-
tieth day, with all the symptoms of inanition.1

The flavor of meat was formerly supposed to depend
chiefly on a peculiar principle, called, by Thenard, osma-
zome. This name is now seldom used, as the substance
which was so called is known to be composed of various em-
pyreumatic nitrogenized products, with lactic acid, the lac-
tate of soda, the inosate of potash, creatine, creatinine, and
other principles, the nature of which has not been deter-
mined.

Most of the vegetable articles of food contain more or
less of nitrogenized principles which resemble very closely
their analogues in the animal kingdom. Some of these vege-
table principles resemble those above considered so closely
that they have been called respectively, vegetable albumen,
fibrin, and casein e. They all, however, present certain dis-
tinguishing peculiarities.

1 MAGENDIE, Rapport fait d T Academic des Sciences au nom de la Commission
dite de la Gelatine. — Comptes Rendus, Paris, 1841, tome xiii., p. 254.

NITKOGENIZED ALIMENTARY PKINCIPLES. 51

Vegetable Albumen. — In the juice of most vegetables
which are used as food, is found a substance, coagulable by
heat and by alcohol, and having the same composition as
ordinary albumen, with the exception of the equivalents of
phosphorus and sulphur. This is found most abundantly in
the juice of turnips, carrots, cabbages, and vegetables of this
class. In wheaten flour, which contains nearly all classes of
alimentary principles, it is also found, but in small quantity.

There is every reason to suppose that, as nutritive prin-
ciples, vegetable and animal albumen are nearly identical.
Many of the largest and strongest animals are nourished ex-
clusively from the vegetable kingdom. The human subject,
and many of the inferior animals, may be nourished at will
by vegetable or by animal food. There is, however, always
a physiological difference in the various nitrogenized prin-
ciples, which is not appreciable by chemical analysis. The
flesh of the carnivora, when used as food, is not the same as
the flesh of the herbivora ; and the quality of meat may be
modified in many animals by changing from a vegetable to
an animal diet. Though the muscular tissue of one animal
may be used for the nourishment of another, the flesh of an
animal thus nourished is not the appropriate food for man.
We should live upon vegetable principles ; taking them in
part directly, and in part indirectly, or after they have been
prepared and assimilated by animals. As a rule, the nutri-
tive principles in vegetables are relatively less abundant than
in animal food, and the indigestible residue is therefore
greater ; but man, and even the carnivorous animals, may
be nourished indefinitely by appropriate articles derived from
the vegetable kingdom. In man, however, the mental and
physical vigor is, as a rule, notably impaired by a strictly
vegetable diet.

Vegetable Fibrin and Caseine. — Many of the vegetable
juices contain a spontaneously coagulable substance which
has been called vegetable fibrin. This is particularly abun-

52 ALIMENTATION.

dant in the cereals. What has been said concerning fibrin,
as an alimentary principle, is applicable to this substance.
Its proportion in vegetables is small, unless we consider as
vegetable fibrin, gluten, one of the most abundant and im-
portant of the nutritive principles contained in ordinary
flour.1

A principle may be extracted from beans, peas, and
other vegetables of this class, which is thought by many to
be identical, in all respects, with caseine, and has been
called vegetable caseine. In Longet we find an account of
an article of food called tao-foo, made by. the Chinese out of
peas, which is apparently identical with cheese.2 The peas
are reduced to a pulp by boiling, the vegetable caseine is co-
agulated by rennet, and afterward treated in the same way as
the analogous substance manufactured from milk. Vegetable
and animal caseine have, as far as we know, identical physio-
logical relations. Yegetable caseine is sometimes called legu-
mine. It is sparingly soluble in water, is insoluble in alco-
hol, is not coagulated by heat, and is precipitated by the
mineral acids and some of the mercurial and calcareous salts.
It is dissolved by the vegetable acids.3

Another substance, supposed by some to be identical
with vegetable caseine, is amandine. This is found widely
distributed in the vegetable kingdom, but it hardly presents
points of distinction from legumine, sufficient to mark it as
a distinct principle.

Gluten. — In many of the vegetable grains known as
cereals, there exists, in variable proportions, a highly nutri-
tive nitrogenized substance called gluten. This is found in
great abundance (from 10 to 35 per cent.) in wheat.4 Its

1 Gluten is a compound substance, containing several distinct alimentary
principles, and cannot be considered strictly as analogous to animal fibrin.

2 Op. cit., tome L, p. 42.

3 NYSTEN, Dictionnaire de Medecine, par LITTRE ET ROBIN. Paris, 1865.
(Legumine.}

* PEREIRA, Treatise on Food and Diet. New York, 1843. See table of pro-

NTTEOGENIZED ALIMENTARY PRINCIPLES. 53

proportion in other grains is insignificant. It may be easily
extracted from ordinary wheaten flour, by kneading under a
stream of water, when the starch, a little sugar, vegetable
albumen, mucilage, and some soluble matters are removed,
and the gluten remains in the form of an adhesive, elastic,
grayish-white mass. Gluten is capable of acting as a ferment,
transforming starch first into dextrine, and then into sugar.
It is the substance which gives the peculiar consistence and
porous character to bread.

The nutritive power of gluten is so great, and it con-
tains such a variety of alimentary principles, that dogs are
well nourished and can live indefinitely on it when taken as
the sole article of food. This experiment was actually made
by the gelatine committee ; * and the fact will be easily under-
stood when we consider that it is a compound of no less than
three distinct nitrogenized principles, together with fatty and
inorganic matters. In one of the methods of treatment of dia-
betes mellitus, in which all saccharine and amylaceous mat-
ters are excluded from the food, it has been found difficult to
nourish the body sufficiently and give proper variety to the
diet without bread ; and, under these circumstances, the use
of bread composed almost exclusively of gluten has been
highly successful. "With proper care, a bread can be made in
this way which is eminently nutritive and not unpalatable.2

portions of gluten in different kinds of grain, p. 9v. These analyses probably
give the proportion of moist gluten.

1 Comptes Rendus, op. «fc, Paris, 1841, tome xiii., -p. 280.

2 It is easy to extract the gluten from wheaten flour, but a difficulty in the
making bread from it is in the excessive " rising " which takes place in the pro-
cess of baking, rendering it light, friable, and disagreeable to the taste. This
difficulty may be overcome by the following process, suggested by Martin de
Crenelle :

The moist gluten is desiccated at a temperature of 212° Fahr. " Thus dried
and reduced to powder, it has lost in great part its tendency to expand. It may
then be used like ordinary flour, kneading it with 66 parts of water to 100 ; a
half a hundredth of yeast is added, and at the end of about a half-hour, the dough
is put in, in the form of a large twist." (PATEN, Precis Theorique et Pratique
des Substances Alimentaires, Paris, 1865, p. 356.)

54: ALIMENTATION.

Gluten obtained by washing flour under a stream of
water contains vegetable fibrin, vegetable albumen, and a
substance soluble in alcohol, called glutine. This latter sub-
stance is found in quantity only in wheaten flour.

In the different articles of food belonging to the vege-
table kingdom, there are undoubtedly many nitrogenized
principles, with the distinguishing properties of which we
are not yet familiar. In their relations to the body as ali-
mentary principles, these would not possess much practical
interest, even if they had all been isolated and studied ; as
all articles of this class are apparently transformed into one
and the same nutritive principle, namely, the albumen of
the blood.

Non-Nitrogenized Alimentary Principles. — The impor-
tant principles belonging to this class are sugar, starch, and
fat. From the fact that these are supposed by some to be
exclusively concerned in keeping up the animal temperature
by the oxidation of carbon, they are frequently spoken of as
the carbonaceous or calorific elements of food. They are
sometimes called hydro-carbons.1

In many respects there are marked and important differ-
ences between the nitrogenized and non-nitrogenized articles
of food ; and whether or not these differences relate to the nu-
trition of the organism, is a question which will be considered in
its appropriate place. The production of animal heat, which
is supposed by some to be due entirely to the action of non-
nitrogenized substances, is closely connected with the function
of nutrition and all that is at present known of this general pro-
cess must be taken into consideration in connection with calo-
rification. It is certain, however, that all alimentary and proxi-
mate principles which contain nitrogen, excluding the inorgan-
ic and some crystallizable organic substances, have very differ-

1 The name hydro-carbon is strictly applicable only to the sugars and starch,
which are, chemically, hydrates of carbon, containing as they do, carbon, with
hydrogen and oxygen in the proportions to form water.

NON-NITEOGENIZED ALIMENTARY PRINCIPLES. 55

ent properties from those which contain no nitrogen. While
the nitrogenized principles are in a state of continual change,
so that it is impossible to fix upon any formula as represent-
ing their exact ultimate composition, the non-nitrogenized
principles are not changed unless by the influence of some
other substance known as a ferment, and have a distinct &nd
definite chemical composition. The latter not only differ
greatly from the nitrogenized principles, but most of the
individual articles of this class present distinctive peculiarities
in their general properties, reactions, and ultimate composi-
tion. Treating of them as alimentary principles, we have
now only to do with their general properties, and the changes
which they may be made to undergo out of the body.

Sugar. — A great many varieties of sugar occur in food ;
and this principle may be derived from both the animal and
vegetable kingdom. The most common varieties derived
from animals are sugar of milk and honey, beside a small
quantity of liver-sugar, which is taken whenever this part is
used for food. The sugars derived from the vegetable king-
dom are cane-sugar, under which head may be classed all
varieties of sugar except that obtained from fruits, and
grape-sugar, which comprises all the varieties existing in
fruits.1 In addition, an impure uncrystallizable residue, ob-
tained in the manufacture of the different varieties of cane-
sugar, called molasses, is a common article of food. The
following are the formulae for the different varieties of sugar
in a crystalline form :

Cane-Sugar, C12 Hn Ou

Milk-Sugar, C12 H12 O12

Grape-Sugar (Glucose), C12 H14 O14

All varieties of sugar have a peculiar sweet taste; they

1 M. Buignet has demonstrated the presence of cane-sugar in quite a number
of fruits, always, however, in combination with a certain proportion of grape-
sugar. (PAYEN, op. tit., p. 241.)

56 ALIMENTATION.

are soluble in water and in alcohol ; they are inflammable,
leaving an abundant carbonaceous residue, and giving off a
peculiar odor of caramel; and are capable of being con-
verted, in contact with ferments and with nitrogenized
principles, into alcohol and carbonic acid, and into lactic
acid. They are also capable of other modifications when
treated with the mineral acids, or with alkalies, which are
interesting more in a chemical than a physiological point
of view.1 Of all the varieties of sugar, that made from the
sugar-cane is the most soluble, the sweetest, and most agree-
able. Beet-root sugar, so extensively used in France, is per-
haps as agreeable, but not so sweet.

Much of the sugar used in the nutrition of the organism
is formed in the body from the digestion of starch. This
transformation of starch may be effected artificially. The
sugar thus formed is called glucose, and is identical in com-
position with grape-sugar. Except in the milk during lacta-
tion, this is the only form in which sugar exists in the organ-
ism, all the sugar taken as food being converted into glucose
before it is taken into the blood.

Starch. — A non-nitrogenized principle, closely resembling
sugar in its ultimate composition (C12 H10 O10), is contained
in abundance in a great number of vegetables. It is found
particularly in the cereals (wheat, rye, corn, barley, rice,
oats), in the potato, chestnuts, and in the grains of legumin-
ous plants (beans, peas, lentils, kidney-beans), in the tuber-
ous roots of the yam, tapioca, and sweet-potato, in the
roots of the Marantd arundinacea* in the sago-plant, in the
bulbs of orchis.3 In the cereals, after desiccation, the pro-
portion of starch is, in general terms, between sixty and

1 The various tests for sugar have been considered in vol. i. (Introduction).

a The creeping roots from which the substance known as arrow-root is manu-
factured.

3 PATEN, Precis Theorique et Pratique des Substances Alimentaires, Paris,
1865, p. 232.

NON-NITKOGENTZED ALIMENTARY PRINCIPLES. 57

seventy parts per hundred. It is most abundant in rice,
which contains, after desiccation, 88*65 parts per 100.1

The proportion of starch in the various vegetable articles
has assumed considerable interest from the fact that in the
mode of treatment of diabetes already referred to, In which
it is the object to prevent the ingestion of sugar or any thing
which may be transformed into sugar, it is proper to allow
certain vegetables, which contain no starch, or a very small
quantity. Payen gives the following list of articles, arranged
in order according to their proportion of starch :

" 1. Parsnips, which contain in their natural condition
6, and desiccated, 29*38 parts per 100 of starch ;

"2. Carrots;

" 3. Pods of string-beans : starch exists in the substance
of the walls of the carpelles? as well as in the young green
beans; but it is not found in appreciable quantity in the
parenchyma which surrounds the beans ;

" 4. Turnips : starch is found principally in the cortical
portion of these tuberous roots ;

" 5. Cabbages : the presence of starch in very small
quantity is recognized in the ribs of the leaves ;

" 6. Cauliflowers : it is at the upper extremity of the atro-
phied buds, forming the head of this horticultural product,
that slight traces of starch are observed.

" "We have not found starch in romaine, lettuce, chiccory,
in the leaves of sorrel, spinage, in asparagus, artichauts, leeks,
nor in the large, early, white onion." s

1 Ibid., p. 265.

8 This is a name given by De Candolle to the elementary organs, free or ad-
herent to each other, the reunion of which gives rise to the pistil, and each one
of which has been regarded as a little leaf folded upon itself. (NYSTEN'S Did.)

3 PAYEN, op. cit., p. 387. In the treatment of diabetes by the exclusion of
saccharine and amylaceous articles of food, it is, of course, important to secure
the greatest possible variety of diet ; and though this is a question of therapeu-
tics, we have thought it not uninteresting nor inappropriate to give a list of vege-
tables which contain no starch, or so little that they may be supposed to furnish
no material for the formation of the sugar which is discharged from the body.

58 ALIMENTATION.

Starch may be separated from many plants by simple
washing, but in others in which it exists in connection with
a considerable proportion of gluten, a more elaborate pro-
cess is employed in commerce. The different varieties of
manufactured starch, such as corn-starch, potato-starch,
arrow-root, tapioca, and sago, differ only in the presence
of a minute quantity of odorous and flavoring principles.

"When extracted in a pure state, starch is in the form of
granules, varying in size from y^foo- to ^^ of an inch, and
presenting, in most varieties, certain peculiarities of form.
The granule is frequently marked by a little conical excava-
tion called the hilus, and the starch substance is arranged in
the form of a concentric laminae, the outlines of which are
frequently quite distinct. When starch is rubbed between
the fingers, these little hard bodies give it rather a gritty
feel, and produce a crackling sound. Most chemists are of
the opinion that the starch-granules are composed of a single
substance, but some contend that each grain is a true vege-
table organ, with an investing membrane composed of nitro-
genized matter.1 The different varieties of starch may be
recognized microscopically by the peculiar appearance of the
granules.

The presence of even a minute quantity of starch in any
mixture which is not alkaline may be readily determined by
the addition of iodine, which unites with the starch, pro-
ducing an intense blue color. The color may be destroyed
by the addition of an alkali, or by the application of heat.
It may be restored, however, by the addition of an acid, or,
in the latter instance, it returns when the mixture is al-
lowed to cool, if the temperature has not been carried to
212° Fahr.

Starch is insoluble in water ; but when boiled with several
times its volume of water, the granules swell up, become trans-

1 BLONDLOT, Recherclies sur la Digestion des Matieres Amylacees, Nancy, 1853,
p. 13.

NON-NITEOGENIZED ALIMENTARY PRINCIPLES. 59

parent, and finally fuse together, mingling with the water,
and giving it a mucilaginous consistence. The mixture on
cooling forms a jelly-like mass of greater or less consistence.
This change in starch is called hyd ration, and is interesting
' as one of the transformations which takes place in the pro-
cess of digestion, when starch is taken uncooked. This change
is generally effected, however, in the process of cooking.

The most interesting properties of starch are connected
with its transformation, first into dextrine, and finally into
glucose. This always takes place in digestion, before starch
can be absorbed. In the digestive apparatus, the change
into sugar is almost instantaneous ; and the intermediate
substance, dextrine, is not recognized. By boiling starch for
a number of hours with dilute sulphuric acid, it gradually
loses its property of striking a blue color with iodine, and is
transformed, without any change in chemical composition,
into the soluble substance called dextrine. If the action be
continued, it assumes four . atoms of water, and is converted
into glucose. If dextrine be perfectly pure, no coloration is
produced by the addition of iodine, but ordinarily it contains
starch imperfectly transformed, and iodine produces a reddish
color. The change of starch into dextrine may be effected
by a dry heat of about 400° Fahr., a method which is com-
monly employed in commerce.

The most effectual method of producing this transforma-
tion of starch, aside from the process of digestion, is by the
action of a peculiar vegetable substance called diastase. This
substance is produced in the process of germination of many
of the vegetables containing starch.1 Its exact chemical com-
position is unknown. One part of diastase will effect the
transformation of one hundred parts of starch, which would
require thirty times the quantity of sulphuric acid.

1 Diastase is a white, amorphous, nitrogenized substance, insoluble in alcohol,
soluble in water, and is extracted from barley, oats, grain, and potatoes, in pro-
cess of germination. Its action upon starch is most energetic at from 150° to
167° Fahr.

60 ALIMENTATION.

What has been said regarding sugar as an alimentary
principle will apply to starch. Though an abundant and
important article of diet, it has been demonstrated by Ham-
mond ' and others to be insufficient of itself for the pur-
poses of nutrition.

Vegetable Principles resembling Starch. — In certain ve-
getables, substances isomeric with starch, but presenting
slight differences as regards general properties and reactions,
have been described, but they possess no very great interest
as alimentary principles, and demand only a passing men-
tion. These are, inuline, lichenine, cellulose, pectose, man-
nite, mucilages, and gums.

Inuline is found in certain roots. It is capable of being
converted into sugar, but does not pass through the inter-
mediate stage of dextrine. It differs from starch in being
very soluble in hot water, and in striking a yellow instead
of a blue color with iodine.

Lichenine is found in many kinds of edible mosses and
lichens. It differs from starch only in its solubility.

Cellulose is a substance, generally regarded as identical
in all plants, which forms the basis of the walls of the vege-
table cells. It exists in greater or less abundance in all
vegetables. It is less easily acted upon by acids than starch,
but is capable, when treated with concentrated sulphuric
acid, of being converted into starch, then into dextrine, and
finally into sugar. It is only in soft and recent vegetable
products that it can be regarded as an alimentary principle.

Pectose is a principle which exists, mingled with cellu-
lose, in unripe fruits, carrots, turnips, and some other vege-
tables of this class. Its composition has not been determined.
In ripe fruits it is found transformed into a soluble substance
called pecline. This transformation may be effected artifi-
cially by the action of acids and heat. Pectine may be pre-

1 Op. tit.

NON-NITEOGENIZED AJLIMENTAJBY PRINCIPLES. 61

cipitated in a gelatinous form from the juices of fruits by
alcohol.

Mannite is a sweetish principle found in manna, mush-
rooms, celery, onions, and asparagus. Manna in tears is
composed of this principle in nearly a pure state. It is
perhaps more analogous to sugar .than to starch, but is not
capable of fermentation and has no influence on polarized
light.

Gums and mucilages may enter to a certain extent into
the composition of food, but they can hardly be considered
as alimentary principles. Gums are found exuding from cer-
tain trees, first in a fluid state, but becoming hard on exposure
to the air. A viscid, stringy mucilage is found surrounding
many grains, such as the flax-seed, quince-seeds, and exists in
various kinds of roots 'and leaves. Both gums and mucilages
mix readily with water, giving it a consistence called muci-
laginous. They have the same composition as starch.

Experiments have shown that gum passes through the
alimentary canal unchanged, and has no nutritive power.1
It is said that gummy exudations from trees form an im-
portant part of the food of certain savage African tribes ;
but it must be remembered that in this condition the exuda-
tion is impure and contains many other substances. Gum
is mentioned in this connection from the fact that it is fre-
quently used in the treatment of disease, and is thought by
many to possess nutritive properties.

Fats and Oils. — Fatty or oily matters, derived from both

Boussingault, out of fifty grammes of pure gum fed to a duck, extracted
forty-six from the faeces. (Memoires de Chimie Agricole et de Physiologic, Paris,
1854, p. 232.) Dr. Hammond ascertained by experiments on his own person
that gum is not only innutritions, but, when taken in quantity, is irritating and
injurious. He attempted to live for ten days on pure gum and water, but was
forced to discontinue his experiment at the end of the fourth day, from excessive
hunger, extreme debility, and fear of inducing serious disease. (Experimental Re-
searches relative to the Nutritive Value and Physiological Effects of Albumen,
Starch, and Gum, when singly and exclusively used as Food. — Trans. American
Med. Assoc., 1857.)

62 ALIMENTATION.

the animal and vegetable kingdom, constitute an important
division of the articles of food. As a proximate principle,
fat is found in all parts of the body, with the exception of
the bones, teeth, and fibrous tissues. It necessarily consti-
tutes an important part of all animal food, and is taken in
the form of adipose tissue, infiltrated in the various tis-
sues in the form of globules and granules of oil, and in sus-
pension in the caseine and water in milk. Animal fat is a
mixture of oleine, margarine, and stearine, in varied propor-
tions, and possesses a consistence which depends upon the
relative quantities of these principles. More or less fat
always enters into the composition of food, but as a rule, it
is more abundantly taken in cold than in warm climates.
The ordinary diet of the Greenlander contains what would
be considered in temperate climates as an enormous quantity
of fat and oil, frequently in a disgusting form, and taken
unmixed with other articles.

The different varieties of animal fats do not demand
special consideration as articles of diet. Butter, an impor-
tant article of food, is somewhat different from the fat ex-
tracted from adipose tissue, but most varieties lose their indi-
vidual peculiarities in the process of digestion, and are ap-
parently identical when they find their way into the lacteal
vessels.

In the vegetable kingdom, fat is particularly abundant
in seeds and grains, but it exists in quantity in some fruits, as
the olive. Here it is generally called oil. Its proportion in
linseed is 20 per cent. ; in rape-seed, 35 to 40 per cent. ; in
hemp-seed, 25 per cent. ; and in poppy-seed, 47 to 50 per
cent.1 It exists in considerable proportion in nuts, and in
certain quantity in the cereals, particularly Indian corn.
Its proportion in the different varieties of wheat is from 1*87
to 2*61 per cent. ; in rye, 2*25 per cent. ; in barley, 2*76 per
cent. ; in oats, 5*5 per cent. ; in Indian corn, 8*8 per cent. ;

1 LONGET, Traitede Physiologic, Paris, 1861, tome i., p. 47.

INORGANIC ALIMENTARY PRINCIPLES. 63

and in rice, O8 per cent.1 The above is the proportion in
the grains after desiccation.

Fat, both animal and vegetable, may be either liquid or
solid. It has a peculiar oily feel, a neutral reaction, is in-
soluble in water and soluble in alcohol (particularly hot alco-
hol), chloroform, ether, benzine, and solutions of soaps. The
solid varieties are exceedingly soluble in the oils. Treated
with alkalies, at a high temperature and in the presence of
water, they are decomposed into fatty acids and glycerine,
the acid uniting with the base to form a soap. Alkaline,
mucilaginous, and some animal fluids (particularly the pan-
creatic juice) are capable of holding fat in a state of minute
'and permanent subdivision and suspension, forming what are
known as emulsions.

The composition of many of the fats and oils has never
been definitely ascertained, on account of the difficulty in
obtaining them in a state of absolute purity. They contain
carbon, hydrogen, and oxygen, but the latter elements do
not exist in the proportions to form water. The composition
of stearine is C71 H70 O8.

As alimentary principles, fats and oils are undoubtedly
of great importance. They are supposed by many to be
particularly concerned in the function of calorification. It
has been proven by repeated experiments that fat, as a single
article of diet, is insufficient for the purposes of nutrition.

Inorganic Alimentary Principles. — Physiological chem-
istry has shown that all the organs, tissues, and fluids of the
body contain inorganic matter in greater or less abundance.
The same is true of vegetable products. All the organic
nitrogenized principles contain mineral substances which
cannot be removed without incineration, and which must be
considered as actually part of their substance. When new
organic matter is appropriated by the tissues to supply the

1 PATEN, Precis TJieorique et Pratique des Substances Alimentaires, Paris, 1865,
p. 265.

64: ALIMENTATION".

place of that which has become effete, the mineral substances
are deposited with them ; and the organic principles, as they
become effete, or are transformed into excrementitious sub-
stances and discharged from the body, are always thrown
off in connection with the mineral substances which enter
into their composition. This constant discharge of inorganic
principles, forming as they do an essential part of the organ-
ism, necessitates their introduction with the food, in order
to maintain the normal constitution of the parts. As these
principles are as necessary to the proper constitution of the
body as any other, they must be considered as belonging to
the class of alimentary substances. This conclusion is inevi-
table, if alimentation be regarded as the supply of material
for the regeneration of the organism.

Water. — This should be placed at the head of the list
of inorganic alimentary principles. It constitutes the great-
est part of the fluids which are used as drink ; l but is seldom,
if ever, taken in a pure state, all potable, waters containing
numerous inorganic salts in solution. A consideration of its
functions as a solvent, and in giving the proper consist-
ence to parts, belongs to the physiological chemistry of the
organism.2 It is always to be remembered, however, that
water forms a part of all the organic nitrogenized principles,
and is indispensable to the manifestation of their vital prop-
erties. It exists, therefore, in all the ' animal and vegetable
nitrogenized elements of food, and serves as the vehicle for
the introduction of all the inorganic salts and the soluble
non-nitrogenized alimentary principles.

Chloride of Sodium. — Of all saline substances, chloride
of sodium is the one most widely distributed in the animal
and vegetable kingdom. It exists in all varieties of food.

1 Water, with the substances which it holds in solution and with which it is
combined, will be taken up more fully under the head of drinks.
3 See vol. i., p. 30 et seq.

INORGANIC ALIMENTARY PRINCIPLES. 65

The quantity, however, which is taken in combination with
other principles is usually insufficient for the purposes of
the economy, and common salt is generally added to certain
articles of food as a condiment, when it improves their flavor,
promotes the secretion of some of the digestive fluids, and
meets a positive nutritive demand on the part of the system.
Numerous experiments and observations have shown that a
deficiency of chloride of sodium in the food has an unfavor-
able influence on nutrition.1

Phosphate of Lime. — This is almost as common a con-
stituent of vegetable and animal food as the chloride of sodi-
um. It is seldom taken except in combination, particularly
with the nitrogenized alimentary principles. Its importance
as an alimentary principle has been experimentally demon-
strated, it having been shown that in animals deprived as
completely as possible of this substance, the nutrition of the
body, particularly in parts which contain it in considerable
quantity, as the bones, is seriously affected.2

Iron. — Hsematine, the coloring matter of the blood, con-
tains, intimately united with organic matter, a considerable
proportion of iron. The examples of anaemia which are
daily met with in practice, and are almost always relieved in
a short time by the administration of iron, are proof of the
importance of this substance as an alimentary principle.
The quantity of iron which is discharged from the body is

1 See vol. i., Introduction.

2 Chossat fed pigeons for a length of time exclusively on wheat which had
been carefully cleaned so as to remove every particle of calcareous matter. He
found that this diet answered very well for three months ; but after that time
diarrhoea set in, and the animals died between the eighth and the tenth month.
One of the most remarkable points in these experiments related to the condition
of the bones, which became excessively thin and fragile. One animal^was found
with both femurs and tibias fractured ; and examined after death, it was found
that the bony tissue had disappeared from many parts of the sternum. None of
these effects were observed when a little carbonate of lime was added to the food.
(Comptes Rendus, Paris, 1842, tome xiv., p. 452.)

5

66 ALIMENTATION.

very slight; a trace only being discoverable in the urine.
A small quantity of iron is frequently introduced in solution
in the water taken as drink, and it is a constant constituent
of milk and eggs. When its supply in the food is insuf-
ficient, it is necessary, in order to restore the processes of nu-
trition to their normal condition, to administer it in some
form, until its proportion in the organism reaches the proper
standard.

It is hardly necessary even to enumerate the other inor-
ganic alimentary principles, as nearly all are in a state of
such intimate combination with nitrogenized principles that
they may be regarded as part of their substance. Suffice it
to say, that all the inorganic matters which exist in the or-
ganism as proximate principles are found in the food. That
these are essential to nutrition, cannot be doubted ; but it is
evident that by themselves they are incapable of supporting
life, as they cannot be converted into either the nitrogenized
or the non-nitrogenized proximate principles.

HAPTEK III.

COMPOUND ALIMENTARY SUBSTANCES.

General considerations — Aliments derived from the animal kingdom — Meats —
Animal viscera — Animal products used as food — Eggs — Milk — Butter — Cheese
— Fishes, reptiles, mollusks, and crustacea-r-Preparation of animal articles of
food — Aliments derived from the vegetable kingdom — Cereal grains — Bread
— Leguminous roots, leaves, seeds, etc. — Condiments and flavoring articles.

ALTHOUGH the number of distinct alimentary principles is
comparatively small, the different articles used as food in the
civilized world are almost innumerable. In the selection of
these articles, the natural instincts of man have become so
developed and modified by habit and education, that little
apparently remains to indicate the character of his original
tastes. The more powerful races, in their conquests and
explorations, have ever regarded the knowledge of new arti-
cles and of new and improved methods of preparation of
food as their most valuable acquisitions from foreign lands ;
until, in the centres of civilization, the luxurious diet of the
epicure comprises the products of nearly every climate and
soil on the face of the globe, prepared with a scientific skill
which is the result of the studies and experience of ages.
Though the necessary and proper diet of man must present
a certain physiological variety, the articles used may be very
simple. All that is requisite is that the different alimentary
principles shall be present in proper quantity, and that they
be not unpalatable nor in such a form as to become dis-
tasteful from monotony. In normal alimentation it is indis-

68 AUMEOTATION:

pensable that the demands of the system be regulated by
exercise and proper habits of life, so that the tastes and the
digestive powers may be always in a physiological condition.
But this is not always the case ; the incessant activity and
the preoccupations of the mind frequently react on the body,
and artificial appetites are easily engendered ; while fancies
and prejudices may become so much a part of the organiza-
tion that the natural instincts are almost buried. An almost
universal tendency to tempt the appetite with food in as
palatable and attractive a form as possible has led to a high
development of the art of cooking. The preparation of food
by cooking has three great objects : one to render it as pala-
table as possible ; another to save and utilize articles which,
without skilful preparation, would be lost ; and another, the
most important in a physiological point of view, to improve
alimentary substances as regards digestibility.

There can be hardly any doubt but that the intelligence
of man is, in the main, correct in recognizing certain arti-
cles, such as tea, coffee, alcoholic beverages, tobacco, etc.,
as capable of temporarily supplying the place of some of the
true alimentary principles, or of diminishing the demand for
nourishment by retarding destructive assimilation.1 Extraor-
dinary physical effort, and, most of all, severe mental exer-
cise, create demands which are not a part of mere animal
existence. It must be regarded as fortunate for the develop-
ment of truth and the progress of the world, that man is
not made to pass his life in accordance with what might be
considered as purely physiological laws. He is the only
being in creation which ever seems to demand that unusual

1 Actual experiment has demonstrated the value of tea, coffee, and occasion-
ally alcohol, within moderate limits, as accessory alimentary principles. In this
statement, an exception might be made with regard to alcohol, the abuse of which
constitutes one of the greatest of human vices. But this does not alter the physi-
ological fact of its value in nutrition, when properly used. The same may be said
of tobacco, though its influence is less decided. Tea and coffee, also, are open
to the objection of being frequently used to excess.

COMPOUND ALIMENTARY SUBSTANCES. 69

kind of nutrition in which the operation of accessory ali-
mentary principles is so conspicuous. It cannot be denied,
however, that the appetites sometimes engendered by great
mental exercise very frequently lead to the most disastrous
results.

Aliments derived from the Animal Kingdom. — The arti-
cles of food derived from the animal kingdom are numerous
and varied. At the head of the list may be placed the dif-
ferent kinds of meat, a name generally applied to the flesh
of the mammalia ; next, the flesh of birds, those most com-
monly used being domesticated, like the fowl, turkey, etc. ;
next, the flesh of fishes, a great variety of which are edi-
ble; and next, certain reptiles which are more or less com-
monly used as food, such as different kinds of turtles, and
sometimes frogs. Some of the mollusks form important
articles of food, more particularly oysters and clams. Some
of the Crustacea are very commonly used, such as lobsters,
craw-fish, crabs, etc. Bees furnish honey, which is not an
uncommon article of diet ; but beyond this the class of in-
sects contributes little or nothing to our food. Finally, cer-
tain animal products, particularly eggs and milk, are impor-
tant aliments.

Meats. — With hardly any exceptions among the mamma-
lia, the flesh of herbivorous animals is the only variety which
is considered fit for food. All animals of this class are not
considered edible. The flesh of the horse, of rats, and many
others is excluded from the table in civilized countries.1

1 In Paris, the attempt has frequently been made to introduce horse-flesh as an
article of food — a movement which found favor to some extent among men of
science. Among the advocates of this article may be mentioned, as the most
prominent, the eminent naturalist and physiologist, Isidore Geoffrey Saint Hilaire.
It has been found impossible, .however, to establish a reputation for horse-flesh
which would give it a place among the meats exposed publicly for sale ; but it
is pretty generally acknowledged that this article is consumed, in spite of the
prejudice against it, under other names. (PATEN, op. cit., p. 59.)

0 ALIMENTATION".

*

Instinctively most persons prefer beef, as an habitual ar-
ticle of diet, to any other variety of meat. The experience
of almost every one has taught that this article can be used
more constantly than any other of its class. ~No meats be-
come so distasteful from constant use as those which are con-
sidered as delicacies, when taken occasionally, such as veni-
son or any variety of game. Any one can realize that it
would be almost impossible to eat a considerable quantity of
any kind of game daily for thirty or sixty days, yet there
are many who, from choice, consume more or less fresh beef
daily for months and years. " Beef-stock " is the basis of
most soups and sauces, and is the main reliance of cooks in
the preparation of what are generally termed made-dishes.
Though of course there are individual exceptions, as there
must be to any rule which may be laid down concerning the
digestibility of different articles, beef is the most easily di-
gested of any of the meats, and its influence upon the nutri-
tion of the body is most favorable. All parts of the muscular
system of the ox possess highly nutritive properties, but
many are more esteemed than others, from superior flavor,
tenderness, and perhaps facility of digestion. It is of course
important that this animal, and others of the same class,
should be of the proper age, well fed, and that the flesh be
kept for a certain time before it is cooked. It is unnecessary
to enter into details with regard to these points.

In China, it is well known that dogs, cats, and rats are exposed for sale in
the public markets, and are extensively used as food. The ordinary prejudice
against the carnivora is generally so far respected in that the avowed consump-
tion of these animals seldom occurs ; nevertheless many are used as food in the
large cities of the world. Following the remarks on horse-flesh, Payen says :
" They regard with as much care a similar prejudice, likewise very wide-spread,
when they serve up to consumers, in the same establishments, carnivora of a
small feline species, raised and nourished with great care, not, it is true, in view
of such a destiny, but which none the less furnish at the occasion a kind of fur,
and a nutritive meat of good quality, presenting, after cooking by the ordinary
method, a very great analogy in appearance and taste with the flesh of the rab-
bit." (Ibid.)

COMPOUND ALIMENTARY SUBSTANCES. Yl

Beef, as well as all kinds of meat, is composed of mus-
cular tissue, a small quantity of blood, and interstitial fat.
"We have already seen that all nitrogenized principles contain
a considerable proportion and a large variety of inorganic
matters. In proximate composition, the different kinds of
meat are quite similar, and the following analysis by Berze-
lius of the flesh of the ox may be taken as the type of the
composition of most of them :

Immediate Composition of the Flesh of the Ox.

Water 7T'1T

Muscular fibre, vessels, and nerves 15'80

Tendonous tissue, reducible to gelatine by boiling. T90

Albumen (analogous to the white of egg and the serum of the blood). . . . 2'20

Substances soluble in water and ilot coagulable by boiling. 1-05

Matters soluble in alcohol 1-80

Phosphate of lime •. 0-08

100-00

According to Payen, among these soluble and insoluble
substances are found lactic and inosic acids, creatine, creati-
nine, and organic nitrogenized matters, with alkaline salts,
magnesian and calcareous. Meat contains, indeed, in 100
parts about 1*5 of soluble and insoluble salts, alkaline chlo-
rides, and phosphates of potassa, of soda and magnesia. Meat
contains beside, a small quantity of sulphur, which is in
part a constituent of albumen of different origin, animal and
vegetable ; sulphur is likewise an integral part of fibre, of the
horny substance of the nails, of hair, etc. It is found neither
in cellular tissue, tendons, fibrous tissue of bones, nor in the
gelatine produced, by a solution at 212° of all these tissues.

" To all these substances indicated by this analysis and

t/ «/

which constitute meats, must be added a saccharine sub-
stance, inosite, analogous to lactose (sugar of milk) and the
fatty substances contained in a special tissue (adipose tissue).
These last substances exert on the quality of the meat a
favorable influence in proportion as, without being in excess^

72 ALIMENTATION.

they are best distributed in the mass. Thus the best
butchers' meat presents in many parts between the muscular
fibres an interposition of fat, which gives them the appear-
ance of a whitish marbling." ]

Taking the above as the type of the composition of the
meats, it is evident that enough variety is here presented to
answer the purposes of nutrition. The carnivora habitually
live upon meat as the sole article of food, and examples are
not wanting in which life is sustained in the same way in
the human subject.

The composition of meat is somewhat modified by cook-
ing. Odorous and flavoring principles are developed, which
render it more agreeable, and the inter-muscular areolar
tissue is softened, by which it is rendered somewhat more
digestible. The following analyses were made by Payen of
beef-steaks, about 1J in. thick, cut from the tenderloin, ex-
empt apparently from adipose tissue.2

Composition of Cooked Beef-steaks.

100 parts gave by analysis the following quantities of water, carbon, nitro-
gen, of fatty and mineral substances :

"Water. Carbon. Nitrogen. Fatty Matters. Mineral Substances.

69-89 16-76 3-528 5-19 1-05

Immediate Composition. Cooked Meat. Dry Substance.

Water 69-89 O'OO

Nitrogenized matters 22-93 76-18

Fatty substances 5-19 17-25

Mineral substances 1'05 3-50

Non-nitrogenized substances, sulphur, and loss 1-04 (0-94 ?) 3-07

100-00 100-00

The composition of other varieties of meat being so much
like that of beef, does not demand special consideration.

1 PAYEN, op. cit., p. 67.

2 Op. cit., p. 92.

In the admirable work of Payen, one of the most complete and exhaustive
treatises on alimentary substances in any language, we find (page 71) a quotation
from remarks made by Chevreul in a discussion at the Imperial and Central So-

COMPOUND ALIMENTARY SUBSTANCES. 73

The preparation of meat by cooking, and the methods which
are employed for its preservation are important, and will be
taken up hereafter. A point in this connection which has
particular physiological and therapeutical interest is the
preparation of soups and animal essences.

Mutton ranks next to beef as an agreeable and nutritive
meat. Nearly all parts of the muscular system of the sheep
are habitually used as food. It is difficult to establish any
great difference in* its nutritive properties from beef; but if
taken constantly, without any variation, it is more apt to
become distasteful — a fact which is important, as showing
that it is hardly capable of supplying indefinitely that vari-
ety of alimentary matter which is so universally demanded.
The flesh of the ram is coarse and of rather a disagreeable
flavor ; but the same may be said of many male animals that
have not been castrated. The flesh of the goat is somewhat
similar to mutton, but is less esteemed.

Next to mutton may be placed pork. This kind of meat
is, perhaps, most frequently used after it has been preserved
by salting or smoking ; but it is often used fresh, and
if thoroughly and properly cooked, it is an agreeable and
nutritious article. The palate will not tolerate fresh pork
as constantly as cured ham, bacon, shoulders, etc. It is to
be remembered that cured pork occasionally contains the
trichina spiralis, and when taken into the stomach un-

ciety of Agriculture of France, on the means of increasing the production of
cattle. Chevreul gives the precedence, as a reparative meat, to beef, and
takes, for purposes of comparison, as an example of beef of the first quality, an
ox, from seven to nine years old, which, after having been worked at the ordi-
nary labor of beasts of that kind, was fattened before being given to the butch-
er. He expresses the opinion that the meat of animals of mature age, exposed
to the fresh air, and in an absolutely normal condition, is better than that of
" precocious " animals, or those that have been fattened with abnormal rapidity.
This is an important point to consider in the selection of all kinds of meat. A
considerable amount of fat, especially interstitial fat, is desirable, as it renders the
meat more tender ; but aside from this, it is safe to assume that the highest
physiological condition of the animal imparts to the flesh the most desirable prop-
erties as an article of food.

74 ALIMENTATION.

cooked these parasites find their way into the muscles, pro-
ducing serious disease, and sometimes death. Since the
disease called trichiniasis, as it occurs in the human subject,
was first described by Professor Zenker, of Dresden, it has
been frequently observed and carefully studied by patholo-
gists. Pork that is thus tainted is called measly. The vi-
tality of the parasite is destroyed by thorough cooking.1

The flesh of various non-domesticated animals is esteemed
highly as food. In some parts of this country, buffalo-meat
is largely used. This is somewhat coarser and of a more de-
cided flavor than beef, but does not differ in its physiological
properties. Yenison is a meat very highly esteemed. This
resembles mutton, but, as a constant article of diet, is by no
means as agreeable. The flesh of the wild boar is used as
food in many European countries. It is darker and more
highly flavored than ordinary pork, and is generally regard-
ed as a delicacy. In this country the raccoon (Procyon lotor\
the woodchuck (Arctomys monax), and the opossum (Didel-
phis Virginiana) are occasionally eaten. These can hardly
be ranked among the delicate varieties of game. They are
not, however, unpalatable, but are excessively fat. Among the
rodentia, we have the hare, most abundant in Great Britain,
the rabbit, and the squirrel, which are very commonly used
as food. Their meat is well-flavored and nutritious. The
English hare is very highly esteemed.

The flesh of many animals is consumed before it arrives
at maturity, as veal, lamb, sucking pig, etc. As a rule, this
kind of meat is whiter, softer, and less nutritious than that
of the adult animal, and develops in cooking less of that aro-
matic principle which adds so much to the agreeable flavor
of meats. An exception may be made in the case of lamb,
which is sufficiently high-flavored, and is rather more tender

1 For an account of microscopic examinations of the muscles of a patient who
suffered from this disease, and examinations of the meat by which it was produced,
see DALTOU, Observations on Trichina Spiralis. — Transactions of the New York
Academy of Medicine, 1864, vol. iii.

COMPOUND ALIMENTARY SUBSTANCES. 75

and delicate than mutton, though, as a constant article of
diet it is not so useful. In the preparation of young meats,
it is necessary to carry the temperature quite high and cook
very thoroughly to develop an agreeable flavor, and it is es-
pecially necessary to have the surface well browned in order
to produce the agreeable aroma which is characteristic of
roast veal, pig, or lamb.

Domesticated and non-domesticated animals belonging
to the class of birds constitute important and highly nutri-
tive articles of diet. They are also useful in furnishing that
variety of food which is so necessary to proper nutrition.
Of the domestic birds, those most esteemed are the common
fowl and the turkey. These should be thoroughly cooked in
order to develop to the highest degree their characteristic
flavor. The dark-meated domestic birds, the duck and
goose, are quite commonly used as food. With the excep-
tion of the fowl, which is very delicate and well-flavored
when young, all domestic birds are most savory and nutri-
tious when they have arrived at maturity ; though after that
time age renders the meat tough and indigestible.

This continent presents a great variety of what are known
as game-birds. Those most esteemed are the partridge, the
quail, and the young prairie-chicken, which have white meat ;
and the wild goose, swan, duck in many varieties, plover,
woodcock, snipe, and birds of this class. The well-grown but
immature white-meated birds are very highly esteemed. The
others should be young but full grown.1

As far as proximate composition and nutritive properties
are concerned, the flesh of birds does not present any great
differences from that of the mammalia. It is to be remarked,
however, that the muscular tissue is never marbled by inter-

1 Prairie-hens, called in this country, grouse, are very abundant in the West-
ern States. When young, the breast and wings are white, but these parts become
dark when they arrive at maturity. Except when very young, these birds are
not so highly esteemed as other varieties of game. The delicious and high-fla-
vored English pheasant is almost unknown in this country.

76 ALIMENTATION.

stitial deposits of fat. Poultry, as a rule, is easily digested
and palatable, when properly prepared ; but the game-birds,
like all other kinds of game, are very decidedly flavored and
become distasteful if used as food too constantly. The young
white-meated birds form very appropriate articles of diet for
persons convalescing from acute diseases.

Animal Viscera, etc. — Although the muscular substance
constitutes the most important parts of animals used as food,
some of the viscera and other parts are occasionally eaten.
The external parts are the feet of pigs and calves and the
skin of the calf s head, which are reduced to a gelatinous
consistence by cooking. They seem to be easily disposed of
by the digestive organs, but are not very nutritious. The
pancreas and thymus of the calf (sweet-breads), the kidneys
of the calf and sheep, the liver of the calf, of the pig, and of
birds, the stomach of the ruminants (tripe), the gizzard,
heart, brains, and tongue, all contain organic alimentary
principles, nitrogenized and non-nitrogenized, and may be
used as occasional articles of diet, but cannot permanently
take the place of the muscular tissue.1 It is a curious physi-
ological fact that blood, the fluid which contains materials
for the nutrition of all parts of the animal, does not appear
to be a nutritious alimentary substance. Payen ascertained
this fact, which the universal distaste for blood as an article
of food would lead us to suspect, by experiments on pigs.2

1 The celebrated pates defoie gras are made of the livers of geese, which are
made to undergo hypertrophy and excessive fatty degeneration by confining the
animals at a high temperature in a small cage, and stuffing them with food. The
pates de Strasbourg are made of these livers, prepared with truffles and other ar-
ticles. They are excessively rich, and are ordinarily considered difficult of di-
gestion.

8 Op. cit., p. 129.

The substance of the bones does not enter, to any considerable extent, into
the diet of the human subject, as it does in the carnivorous animals. The exper-
iments of Magendie, detailed in the report of the " Gelatine Commission " ( Oomptes
Rendus, Paris, 1841, tome xiii., p. 254), showed that dogs can live indefinitely on
a diet composed exclusively of uncooked bones.

COMPOUND ALIMENTARY SUBSTANCES. 77

Animal Products used as Food — Eggs. — The eggs of
various birds are frequently used as food, but those of the
common fowl are by far the most esteemed. They contain,
necessarily, all the principles which are demanded in the
development of the chick, and are exceedingly nutritious.
They are taken sometimes raw, but most frequently cooked,
and in a great variety of forms which it would be out of
place even to enumerate. The white of egg uncooked, or
imperfectly coagulated, is ordinarily more digestible than
when it has been rendered solid by prolonged boiling.

It is only necessary to refer to the composition of eggs to
appreciate their nutritive value. According to Payen, the
egg contains " nitrogenized substances (membranes, albu-
men, vitelline, extract of meat, yellow coloring matter) ;
fatty matters (margarine, oleine, cholesterine, etc., margaric,
oleic, and phospho-glyceric acids) ; a saccharine matter, sul-
phur, phosphorus, and mineral salts ; phosphates of lime and
magnesia, chlorides of sodium and potassium, carbonate of
soda." * In addition, the important principle, iron, is always
found in the ash after incineration. The white is composed
chiefly of albumen with inorganic salts ; and the yolk, of
vitelline, with a large quantity of oil in the condition of an
emulsion.

Milk. — At certain periods of life milk is the sole article
of food, and it must be regarded as at all times one of the most
nutritious and important of the animal products, being used
largely in its natural form, and furnishing butter and the
numerous varieties of cheese which are so largely consumed.
The composition of milk affords an explanation of its high-
ly nutritive properties. It contains a large amount of ni-
trogenized material, composed in greatest part of caseine,
but containing albumen, and another principle not very well
determined, called lacto-proteine ; fatty matter in abundance,
composed of a variety of principles of this class (oleine,
1 Op. dt., p. 130.

78 ALIMENTATION.

margarine, butyrine, and one or two other unimportant va-
rieties) ; sugar of milk ; coloring matter, and finally, a great
variety of inorganic salts, including a combination of iron.

Cows' milk, which is the variety most commonly used,
has, according to Payen, the following composition : l

Composition of Cows' Milk.

Water 86-40

Nitrogenized substances (caseine, albumen, lacto-proteine, and matters

soluble in alcohol) 4*30

Lactose (sugar of milk or lactine) 5'20

Butter (or fatty matters) 3'70

A trace of coloring and aromatic matters.

( Phosphate of lime )

Salts, slightly soluble < " " magnesia ( 0-25

( " " iron }

C Chloride of sodium }

Soluble salts < " " potassium V 0-15

( Phosphate and lactate of soda )

100-00

The quality of milk is usually considered with reference
to its reaction, specific gravity, and its proportion of fatty
matter. When perfectly fresh it is neutral or sometimes
slightly alkaline. In a short time it becomes faintly acid, and
its acidity is increased by the transformation of a portion of its
sugar into lactic acid, until this becomes sufficient to coag-
ulate the caseine. It is then said to be soured, and separates
into the curd and whey. In this state it is not unwholesome,
1 Op. dt, p. 139.

It is hardly necessary to describe fully the other varieties of milk which are
used as food. The milk of the goat, ass, mare, reindeer, and sheep are some-
times used, and present certain differences from cows' milk. In general, the
odorous principles are distinctive. Goats' milk contains much more butter and a
little more caseine and sugar than cows' milk. Ewes' milk contains a large excess
of caseine and butter, but is rather deficient in sugar. Asses' milk contains a rel-
atively small proportion of caseine and butter, and a large proportion of sugar.
Mares' milk contains a very large proportion of sugar (8'75 per hundred), a small
proportion of caseine, and very little butter. Human milk contains less caseine
and more sugar and butter than cows' milk. This will be more fully considered
in the section devoted to secretion.

COMPOUND ALIMENTARY SUBSTANCES. 79

and to some persons is agreeable. Its specific gravity is
. about 1,030, though this is subject to considerable variations.
The proportion of cream in milk of good quality is from ten
to fifteen parts per hundred by volume. Ordinary milk
hardly contains so much. Milk that contains more than
fifteen per cent, of cream may be regarded as excessively
rich. These indications may be easily obtained by allowing
milk to stand for twenty-four hours in a graduated glass
tube. These little instruments, called lactometers, are fre-
quently used for testing the milk of wet-nurses. It has been
found that the proportion of fatty matter in cows' milk is
much greater toward the end of a milking than at first. In
an observation by Quevenne, during the first part of the milk-
ing the proportion of cream was five per cent., during the
middle period fifteen per cent., and during the last period
twenty-one per cent.1

The diet of the animal has an important influence on the
quality of the milk and butter. Almost every one is famil-
iar with the peculiarly disagreeable flavor of these articles
when the cows have had access to leeks or onions. Except
when animals are fed in pastures of great richness, the best
milk is obtained by feeding judiciously in the stable, taking
care to give water at proper intervals, to clean the animals
carefully, and to allow sufficient exercise, with opportunities
for rubbing the hide, etc.

Cream, though of less specific gravity than milk, under
certain conditions is much more nutritious. Added to other
articles of food, it frequently corrects defective nutrition more
effectually than cod-liver oil, or any article that may be ex-
hibited for that end. It contains a large quantity of fat, and
has a very delicate and delicious flavor.

Buttermilk, the residue in the manufacture of butter,
contains all the constituents of milk except the fatty mat-
ters, and is frequently used as an article of diet, particularly

1 In PATEN, op. cit., p. 145.

80

ALIMENTATION.

in rural districts. It is agreeable, easily digested, and con-
tains a considerable amount of nutriment. It is frequently
useful in therapeutics, when other nutritious articles are not
well borne.

Butter. — The only variety of butter used as food is that
inade from cows' milk ; from which it is extracted by mechan-
ically breaking up the oil globules, and causing their fusion into
a homogeneous mass. It usually contains about one-sixth of
its weight of buttermilk.1 The best butter is made out of
rich milk of good flavor, and contains only the flavoring prin-
ciple of the cream, which is but slightly altered. In poor quali-
ties of butter, either the milk has been inferior, or the fatty
acids are freely developed. In this country butter is gener-
ally salted, but in many parts of Europe it is used fresh. It
is an exceedingly important article of diet in all parts of the
civilized world. . Its important, and almost its sole aliment-
ary principle, is fat, and it therefore demands no considera-
tion beyond that which has already been given to this class
of principles.

Cheese. — The coagulated nitrogenized constituents of
milk, combined with a greater or less quantity of butter and
inorganic salts, the more watery portions having been re-
moved by pressure, constitute the important article of food
called cheese. In this country, cheese is ordinarily so pre-
pared and protected that it will keep for a length of time,
and it becomes, in some instances, considerably improved by
age. Its manufacture constitutes an important branch of
industry in many sections, particularly those in which, from
the quality of the pasture, the milk is unusually rich and
well-flavored. In the ordinary form it is somewhat salted,
and pressed into immense cakes or disks. The alterations

1 PEREIRA, Treatise on Food and Dlct^ edited by Charles A. Lee, M. D. New
York, 1843, p. 86.

COMPOUND ALIMENTARY SUBSTANCES. 81

which cheese undergoes are usually connected with the de-
velopment of volatile principles from its fatty constituents.
In addition, it is sometimes attacked by mould, by the larvae
of a peculiar kind of fly, and by the ordinary cheese-mite.
The blue mould is thought by many not to injure the qual-
ity of cheese, and some even regard the development of
skippers and mites as an improvement. Ordinary new
cheese is a highly nutritious article, as is evident from
its composition, but by many is not very easy of digestion.
Old cheese, taken in small quantity toward the close of a re-
past, undoubtedly facilitates digestion by stimulating the se-
cretion of the fluids, particularly the gastric juice.

The following is the composition of Cheshire cheese,
which many of the American cheeses closely resemble : l

Composition of Cheshire Cheese.

Water 85-92

Nitrogenized matters (representing 4'126 of nitrogen) 25'99

Fatty matters (representing 41'11 for the cheese desiccated) 26'34

Salts (by incineration) 4'16

Non-nitrogenized matters and loss , . . 7*69

100-00

The foreign cheeses which those made in the United
States most nearly resemble are made in England ; and al-
though the real Cheshire, Stilton, and Cheddar cheeses are
undoubtedly the best of their kind, they have been very suc-
cessfully imitated in this country.

The French market abounds in delicious varieties of
cheese, many of which are fresh and very different from the
articles ordinarily used in this country. Their richness and
excellence, as indeed the good qualities of all cheeses, depend
upon the quantity and quality of their fatty constituents.
The fresh Neufchatel cheese contains 8 per cent, of nitrogen-
ized matter, and 40 per cent, of butter.2 Almost all of the

1 PATEN, op. at., p. 209.

9 This variety of cheese is very successfully imitated in New Jersey, opposite
the city of New York, and is frequently sold as the true imported article.
6

82 ALIMENTATION.

different varieties of cheese are made from the milk of the
cow ; but the celebrated Roquefort is made from ewes' milk,
which, as we have seen, is excessively rich in butter.

There is no very great difference in the varieties of cheese
as regards nutritive properties, except that some, particularly
the fresh cheeses, are more easily digested than others. The
different varieties are severally sought after on account of
their peculiar flavor. Some of the imported cheeses, partic-
ularly the German, if we may judge from the odor, are eaten
after putrefaction has considerably advanced ; but, though
taken in considerable quantity, they seem to produce no ill

effects in those accustomed to their use.

»

Fishes, Reptiles^ Mollusks, and Crustacea. — The varieties
of fish consumed as food in different parts of the world are
innumerable. Many, such as the cod, mackerel, salmon, and
certain varieties found in the great interior lakes of North
America, are taken in immense quantities at particular sea-
sons, and are preserved for use, either by salting, smoking,
pickling, or drying. The flesh treated in this way is capable
of nourishing the body only when combined with other arti-
cles, as the processes for its preservation, particularly salting,
diminish its nutritive value, which is always considerably
below that of meat. As an article of diet it is nevertheless
important in contributing to the necessary variety in the nu-
tritive principles. Though ordinarily but an accessory article
of food, fish may constitute the important animal element ;
and there are localities where the inhabitants subsist almost
entirely upon" it, and are well nourished.

The muscular tissue of fish presents the same constituents
as that of the higher classes of animals, but the proportion
of solid materials is smaller. The roe (or ovaries), milt (or
testicles), and swimming-bladder (or sounds), are sometimes
used as food, and in some varieties of fish, as the shad and
cod, are highly esteemed.

We will not attempt to even enumerate the varieties of

COMPOUND ALIMENTARY SUBSTANCES. 83

fish which are used in alimentation, or then* differences in
composition, etc. Suffice it to say, that a great number are
ranked among the most delicious articles of food, and the
skill of the cook is taxed to the utmost to prepare them for
the table. Almost all kinds of fish are easy of digestion, as
every one can bear witness from personal experience, except
perhaps those which abound in oily matters, as salmon, eels,
etc. Fish, to be eaten in perfection, should be taken at the
time of full development of the generative organs, but not
just before spawning, nor immediately after. The male, or
soft-roed fish, is considered superior to the female. It is de-
sirable always to eat fish as soon as possible after they are
taken from the water.

The food of fish has an undoubted influence on their
quality. It is now not unusual to confine them in ponds,
where they may be fed and fattened till they grow to an
enormous size, and become exquisitely delicate in flavor.
By carefully protecting the spawn and the young fish they
may be multiplied to a prodigious extent ; for the eggs de-
posited by a single one in a season are numbered by thou-
sands.

The flesh of fish resembles young meat in requiring thor-
ough cooking to develop its flavor and render it easy of di-
gestion.

In the class of reptiles, certain varieties of the turtle are
the most important as articles of food. The large sea-turtle,
known as the green turtle, weighing sometimes several hun-
dred pounds, is used chiefly for soups. The flesh is some-
times cut into steaks and broiled, but is not very much es-
teemed in that form. A small animal of this class, the salt-
water terrapin (Emys palustris), about five inches in length,
is found in its perfection in brackish streams near certain
parts of the Atlantic coast of the United States. This is
considered one of the greatest delicacies peculiar to this
country. It is highly nutritious, its flavor is very decided,
and is to most persons very agreeable. Various of the small

84: ALIMENTATION.

fresh-water turtles are used for coarse soups, but are not
much esteemed ; except, perhaps, the gopher (Testudo poly-
pfiemus), which is used to some extent in the Southern
States. The meat of turtles, when boiled, becomes white,
and resembles veal in its general appearance.

The hind quarters of the larger varieties of the frog (Rana
esculenta and Rana catesboeana) are sometimes cooked and
eaten. Though it is a common impression that this article
is chiefly used on the continent of Europe, it is probably as
common in certain parts of this country as anywhere. The
flesh is white, delicate, without much flavor, and but slightly
nutritious.

In some of the wild and unsettled parts of the North
American continent, snakes, particularly the rattlesnake
(Orotalus adamanteus\ are sometimes cooked and eaten,
though not very frequently as a matter of choice.

Reptiles are not used as food in sufficient abundance to
constitute important alimentary articles. The flesh is not
very nutritious, and they must be considered simply as occa-
sional articles of luxury.

The most important article of food belonging to the class
of mollusks is the oyster. In addition there are the different
varieties of clams — the salt-water clams being most esteemed
— mussels, scallops, and a kind of snail called the escargot.
The oyster in this country is an important article of diet, but
the other mollusks are little used. Clams are chiefly used for
soups. The flavor is agreeable, but the clams themselves are
not generally much esteemed. Mussels, scallops, etc., are not
much used as articles of luxury. Snails are consumed in
France, but are used very little elsewhere.

The oyster in its greatest perfection exists in artificial
beds along certain parts of the sea-coast of the United States.
Statistics are wanting to show the extent to which oysters
are consumed in the large seaport cities, but the quantity is
enormous, to say nothing of those which are transported to
the interior in kegs and cans. The best American oysters

COMPOUND ALIMENTARY SUBSTANCES. 85

are large enough to be cooked in a variety of ways, and their
flavor when developed by cooking is superior to that of any
in the world. They are frequently taken raw, when the
small, firm, and salt oysters are most esteemed. Taken this
way they compare favorably with the best European oysters ;
but have, perhaps, hardly the delicacy of flavor of the cele-
brated Ostend oysters.1 Aside from peculiarities in different
individuals with regard to the digestibility of particular ar-
ticles, the oyster must be considered as highly nutritious and
easily digested. It is acted upon by the digestive fluids more
easily in the raw state than when cooked, even in the sim-
plest manner. Proximate analyses of the oyster show a
considerable quantity of organic nitrogenized matter, fat,
and the inorganic salts. The proportion of solid matter is
about five per cent.2

The liquor contained in the oyster-shell is also used, es-
pecially in cooking. It is impregnated with the flavor of the
oyster, and contains a small quantity of nitrogenized and
non-nitrogenized matter.

Many varieties of the Crustacea are used as food ; but they
are important simply as articles of luxury, and as contrib-
uting to the necessary variety in the diet. These are gener-
ally spoken of as shell-fish, a name which is sometimes un-
derstood to include the mollusks. The most important arti-
cles of this class are lobsters, crabs, and shrimps. As a gen-
eral rule, the flesh of the Crustacea, though reputed to be
quite nutritive, is difficult of digestion. In this country the
ordinary lobster, and the crab just after it has shed its shell
(the soft-shelled crab), are most highly esteemed.

1 In Europe, several dozens of oysters are frequently eaten as a preparation
to the more solid portions of a dinner ; and when taken at other times, they are
eaten by fifties and hundreds. In this country the oysters are so large that a
dozen is considered a very fair allowance at any time.

2 Payen (op. cit., p. 221) gives the proximate composition of the French oys-
ter, which probably does not differ much from other varieties except in size
and flavor. The proportion of nitrogenized matter is about 14 parts per 100.

86 ALIMENTATION.

Preparation of Animal Articles of Food.

The preparation of food by cooking is designed to disin-
tegrate its tissue, to develop flavors which will be agreeable
to the taste and stimulate the secretion of the digestive fluids,
and to prepare the alimentary principles so that they may
be readily separated, liquefied, and finally absorbed. Many
of the culinary processes accomplish these ends, but others
are eminently unphysiological. Fortunately the latter, as the
rule, do not render the food more agreeable to the palate.

One of the most important questions, in a chemico-phys-
iological point of view, connected with the preparation of
animal food, is with regard to the principles which are ex-
tracted from the various meats by prolonged boiling in water :
for this is the mode of cooking which is frequently employed
in hospitals and other institutions where it is desirable to pre-
sent in the articles of diet an exact amount of nutritive ma-
terial. This important subject has been investigated by the
many eminent physiologists and physiological chemists,
among whom may be mentioned as most conspicuous, Ma
gendie, Chevreul, Liebig, and Payen.

By subjecting meat to prolonged and gentle ebullition in
water, certain principles are volatilized and given ofi*. These
are ammonia in small quantity, an odorous principle pecu-
liar to the kind of meat used, and certain volatile acid prin-
ciples. Certain of the constituents of the meat may be dis-
solved by maceration in cold water, and quite a number of
organic principles are dissolved by boiling. While it must
be acknowledged that the concentrated animal broths present
a considerable amount of nutritive material in a condition in
which it is very easily digested, chemical analysis shows such
a small proportion of solid matter that we are surprised that
they possess so much nutritive power. Soup ordinarily con-
tains a small quantity of gelatine, formed by a transforma-
tion and solution of some of the organic matter of the bones
and the fibrous tissue, creatine, an organic nitrogenized mat-

PREPAKATION OF ANIMAL ARTICLES OF FOOD. 87

ter formerly called osmazome, and numerous inorganic salts.
The proportion of solid matter in soups is ordinarily from
nine to ten parts per thousand. Coagulated albumen, a
portion of the fat, and certain inorganic salts are removed in
the scum. The boiled meat contains musculine, somewhat
hardened and corrugated, coagulated albumen, fat, and in-
organic salts.- In the preparation of the different soups, va-
rious vegetables are commonly used, which add to the flavor
and supply a certain quantity of nutritive matter.

The following formula, the result of numerous experi-
ments, is now adopted for the preparation of soup for the
hospitals and civil charitable institutions of Paris.1

Formula for making Soup.

For 20 gal. of bouillon.

Water 20 gal. (75 lit.)

Meat, weighed with the bones 68 Ib. 10 oz. (31-245 grammes.)

Vegetables 13 Ib. 10 oz. (6-240 do. )

Salt 1 Ib. 12| oz. (0-840 do. )

Burnt onions (baked in an oven until desiccated) 7f oz. (0.220 do. )

The capacity of the kettles used should never exceed
twenty gallons, as in larger vessels the pressure on the lower
strata of the liquid causes the temperature to rise too high,
and the aroma is thereby in part destroyed. The meat
should be cut off from the bones and tied with strong cords
into packages of nine or ten pounds each. The bones should
be broken up and placed in the bottom of the kettle. The
packages of meat should then be placed upon a grating or
perforated false bottom, above the bones. Twenty gallons
of cold water are then poured in, the whole is raised to the
boiling point, and the scum is removed as it forms. It is
kept gently boiling for two hours, during which time it is
constantly skimmed. Between the first and second hour,
when the skimming is nearly completed, the vegetables with

1 PAYEN, op. cit., p. 101. The weights and measures have been reduced from
the French to the English standard.

88 ALIMENTATION.

the burnt onions are introduced enclosed in a net-bag. A
gentle ebullition is then maintained for four or five hours.
The fire is then extinguished, and after about an hour the
vegetables, the meat, and the bouillon are taken out. When
the latter is to be used, the congealed fat is taken from the
top, and the bouillon is mixed with about the same quantity
of water and heated to make the soup.

The simplest and most rational mode of cooking meats is
by roasting or broiling, both of these methods being essentially
the same in their operation. In this way none of the nutrient
principles are lost, and the flavor peculiar to each variety of
meat is most effectually developed and preserved. These
operations should be so conducted that the most superficial
portions of the meat are suddenly exposed to a temperature
of from 212° to 270° Fahr. ; while in the interior the tem-
perature ranges from 125° to 150°. In this way the exter-
nal parts are corrugated and hardened, so as to retain all of
the juices, which are set free to a considerable extent by the
more moderate heat in the interior. The nutritive principles
of cooked meats seem to be more readily assimilated when
the red coloring matters are not thoroughly coagulated. The
art in broiling or roasting depends upon an observance of
these cardinal principles. These rules are specially appli-
cable to the fully-developed meats and to the dark-meated
birds. Young meats, such as veal or lamb, and the white-
meated birds, require a higher temperature throughout, and
a more thorough cooking.

Many meats are well prepared by boiling, when the ob-
ject is to cook thoroughly and render the meat tender, but
to extract as little of the juices as possible. For this purpose
salt is generally added to the water at first. The meats
should be placed in cold water and boiled over a sharp fire.
If put immediately into boiling water, the tissue becomes
toughened. In stewing, meats are rendered tender and
the juices are extracted but are preserved in the gravy. In
baking, the interior of the meat is subjected to a higher tern-

ALIMENTS DERIVED FROM THE VEGETABLE KINGDOM. 89

perature than is desirable, which has rather an unfavorable
influence on its flavor and digestibility.

All who have investigated the physiological relations of
cooking declare that frying is the most objectionable mode
of preparation of meat. The temperature to which the meat
is exposed in this process is very high, and the flavor and
nutritive properties are thereby greatly impaired. Meats
prepared in this way should be coated with crumbs or batter,
which prevents, to some extent, the penetration of the hot
fat.

It is unnecessary to discuss the methods employed in the
preparation of the mollusks, Crustacea, etc., which are to be
regarded generally as articles of luxury ; and a consideration
of condiments, spices, and various vegetable articles used
in refined cooking would be out of place, as they refer chief-
ly to the taste, and have no direct bearing on nutrition.
Some articles are most palatable when cooked in the sim-
plest way ; but others are improved by the addition of fla-
voring principles, among the most remarkable of which is
the world-renowned truffle, which, when judiciously used,
imparts its delicious perfume to the meat, but takes away
nothing of its peculiar flavor. The truffle is especially es-
teemed in the cooking of white-meated birds.

When we come to consider specially the different diges-
tive processes, it will be seen that proper preparation of food
greatly facilitates its digestion and assimilation. In the
hygiene of armies, of charitable institutions and hospitals,
and of individuals, there are few things more important than
an observance of the great physiological principles of the art
of cooking.

Aliments derived from the Vegetable Kingdom.

We have seen that some of the most important aliment-
ary principles are derived from the vegetable kingdom.
Starch, and preparations which are composed chiefly of
this principle, sugars, and the vegetable oils, have already

90 ALIMENTATION.

been considered with sufficient minuteness. It remains
now to treat of the composition and properties of some
of the more important vegetables and the articles which are
made from them, particularly the different kinds of bread.
The various fruits, many of which are mere articles of luxury,
demand only a passing mention.

Cereal Grains. — The cereal grains commonly used as
food are wheat, Indian corn, rye, buckwheat, oats, barley,
and rice. Wheat, corn, rye, buckwheat, and oats, are gen-
erally ground, freed from the bran, and the flour or meal is
made into bread, cakes, gruel, or porridge. Barley, rice,
and green corn, are frequently taken after simple boiling.
The articles made from these different grains possess differ-
ent nutritive properties, though they are all more or less
important, Wheaten flour is the only preparation of the
cereals capable of making that most important of all aliment-
ary articles, good bread. The mechanical properties of moist
gluten enable us to form from flour, by the process known
as raising, a light, porous bread, which is entirely different
from articles manufactured from meal of any other kind.

Wheat must be considered as by far the most nutritious
of all grains. It contains, after desiccation, from fifty to
seventy-five per cent, of starch, from ten to twenty per cent,
of nitrogenized matters, about two per cent, of fatty matter,
six to ten per cent, of dextrine and sugar, two to three per
cent, of inorganic salts, and a certain quantity of cellulose.
It is distinguished from all other grains by its large propor-
tion of glutine. When we come to consider the composition
and properties of bread, we will see the great importance of
this principle.

Corn is distinguished from other grains by its large pro-
portion of oily matter (between eight and ten per cent.),
by a peculiar odorous principle, and by its small propor-
tion of nitrogenized matter. It contains a larger propor-
tion of indigestible vegetable tissue than any of the grains,

ALIMENTS DERIVED FROM THE VEGETABLE KINGDOM. 91

excepting oats. In this country, some of the earlier and
more tender varieties, commonjy called sweet corn, are used
as a fresh vegetable, being simply boiled or roasted ; and
in this form are nutritious, and, as a rule, easily digestible.
Corn-meal is used in the preparation of what is called corn-
bread and various cakes and puddings. Corn -bread is a very
common article of diet in the Southern States. Articles made
from corn-meal cannot take the place of wheaten bread ; and
when not carefully prepared are apt to cause diarrhoea in
persons not accustomed to their use. On account of the
proportion of oil, corn and corn-meal are very useful in fat-
tening animals, particularly swine. In the large cities of the
United States and in Europe, corn-meal is not a very im-
portant article of diet.

Rye-meal is sometimes used to make bread. The bread
is more compact than wheat-bread, has a peculiar taste, a
brown color, and is less nutritious. In many parts of the
world rye is used instead of wheat on account of its cheap-
ness ; and in this country it is sometimes used with the idea
that it is more digestible and nutritious. It makes very good
bread, but cannot take the place of wheat. In composition
rye is distinguished from wheat in containing less nitrogen-
ized matter and a larger proportion of dextrine and sugar.

Buckwheat does not differ materially from rye, except
that it contains very much less dextrine and sugar. In this
country it is seldom used except in. making baked cakes,
which are here very highly esteemed. In some of the poorer
sections of the old world, buckwheat mixed with wheat-flour
is used in making bread ; but this is only on account of its
cheapness, for it does not improve the flavor of bread, and is
much inferior to wheat in nutritive properties.

Oat-meal is not an important article of diet in this
country, though it is largely used in Scotland and some of
the northern parts of England. It contains a large propor-
tion of oil, over five per cent., writh peculiar aromatic princi-
ples. It is very much used as food for horses ; and for this pur-

92 ALIMENTATION.

pose no other grain can take its place. The oat-cakes, which
are so common in Scotland, are apt to produce diarrhoea in
persons not accustomed to their use.

Barley is not a very important article of diet. In com-
position it resembles rye. Barley-water, a mucilaginous
drink made by boiling barley, contains gum and a small pro-
portion of nutritive material, and is often used in therapeu-
tics as an agreeable demulcent drink. Malt, which is so
largely used in brewing, is produced from barley which has
been made to germinate by heat and moisture. It is in this
process that the ferment called diastase is produced.

Rice is produced in abundance in low, swampy lands in
certain parts of the United States, particularly South Caro-
lina. Millions of people in Eastern countries are said to sub-
sist almost exclusively on this article. For this reason it is
regarded by many as highly nutritive, though analysis shows
that it contains a comparatively small proportion of nitro-
genized matter, its chief ingredient being starch. The pro-
portion of starch in rice is nearly ninety per cent. It is prob-
able that the nutritive properties of rice have been much
exaggerated. When it constitutes the greater part of the food,
it is consumed in enormous quantities ; and in those coun-
tries in which the inhabitants are said to live exclusively
upon it, other articles which contain an abundance of fatty
and nitrogenized principles are mixed with it. Although
rice is considerably used in civilized countries, it is not a very
important article of diet. It is used chiefly in puddings, del-
icate cakes, and sometimes in soups, or simply boiled.

Bread.

There is probably no animal nor vegetable article of food
that presents so admirable a combination of alimentary prin-
ciples as that which is appropriately denominated " the staff
of life." This fact is corroborated by its universal accept-
ance as the prime article of diet in all civilized countries.
It is an article which never becomes distasteful from monot-

BREAD. 93

ony, demonstrating in this how completely it meets the
wants of the system. A comparison of the composition and
properties of the different cereal grains has made it evident
that in the manufacture of bread nothing can take the place
of the alimentary principles contained in wheat. Of the dif-
ferent varieties of wheat, that which is known as the hard
grain makes the best and most nutritious bread. In some of
the poorer sections of the old world the quality of the bread
is impaired by the mixture of rye, buckwheat, etc., with
wheaten flour ; but in this country this is never done, and, as
the rule, the quality of bread depends entirely on the skill
employed in its manufacture. It is evident that there are few
questions connected "with alimentation which have greater
importance than the scientific principles involved in the
making of bread. In this particular we may safely follow
the French, as they undoubtedly make the best bread in the
world.1

Of course, the starting-point in the manufacture of good
bread is to have good flour, in the production of which this
country is unsurpassed. The first operation in making bread
is to mix with one hundred parts of flour from fifty to sixty
parts by weight of water, adding a little salt, and fresh yeast
in the proportion of about half an ounce to ten pounds. The
mass is then thoroughly kneaded until it forms an elastic,
homogeneous dough. Some bakers are in the habit of adding
to the dough a little potato and alum ; but these must be
regarded as adulterations, although the potato is not inju-
rious. "When the dough has been thoroughly kneaded, the
gluten is so mixed with the other ingredients and is so tena-
cious and elastic, that the surface will not be broken by the
gas which is to be evolved in its interior. It is then divided
into loaves, and set aside for from six to eight hours, at a
temperature of from 80° to 100° Fahr., to " rise."

1 The essential parts of the process of making bread are taken from the ad-
mirable work of Payen, which has already been so frequently alluded to in con-
nection with alimentation.

94 ALIMENTATION.

The process of raising or fermentation, called sometimes
panification, is characterized by several important changes
in the composition of the flour. These changes may take
place spontaneously from decomposition of the gluten and
its action as a ferment, or they may be induced, as is com-
monly the case, by yeast, or by gluten already in process
of decomposition, called leaven. The process of panifica-
tion involves three kinds of action, viz., the alcoholic, the
acetic, and the lactic acid fermentation. The alcoholic fer-
mentation is due to a decomposition of the small proportion
of sugar which the dough contains into carbonic acid and
alcohol. But this is not the only source of these principles.
A certain quantity of the starch is converted first into dex-
trine and afterward into sugar, which finally undergoes al-
coholic fermentation. The evolution of gas in this way
raises the dough, and forms little cavities in the bread, which
give it its peculiar porous character ; the elasticity and te-
nacity of the gluten allowing the dough to swell, and retain-
ing the gas in its interior. As gluten is particularly abun-
dant in wheaten flour, it is from this only that good light
bread can be made.

When the dough has been sufficiently raised, it is put
into the oven and baked. The application of heat at first
increases the development of gas, but when the temperature
is raised to 212°, the process of fermentation is arrested ; and
afterward the baking simply cooks and fixes the dough in its
expanded condition. The alcohol generated in the process
of raising is volatilized and driven off in the baking.1 The
superficial portions of the loaf are exposed to a temperature
of about 375°, by which they are hardened, forming the crust,
and a portion of the starch before unaltered is transformed into
dextrine. It is well known that the crust of bread contains

1 A number of years ago a patent was taken out in England for a process for
collecting the alcohol evolved in baking bread. The project succeeded as far as
collecting the alcohol was concerned, but failed as a commercial operation. (PE-
REIRA, Treatise on Food and Diet, New York, 1843, p. 147.)

BREAD. 95

more soluble matter than the interior. The temperature of
the interior is not raised much, if any, above 212°. The
acidulous fermentation takes place to a limited extent even
in good white bread ; but this is apt to proceed further than
is desirable if the dough be allowed to ferment too long. In
that case the bread is sour and indigestible.

Brown bread may be made either of unbolted flour, or of
flour to which a small quantity of bran has been added. A
bread called bran-bread is made of an excess of bran with a
small quantity of flour. The bread formerly issued to the
French soldier (pain de munition) was made from flour with
only 15 per cent, of its bran removed ; unbolted flour con-
taining about twenty per cent. The color of this kind of
brown bread is due, not to the color of the bran, but to pe-
culiarities in the process of panification. In the bran is
contained a peculiar principle called cerealine, which is ca-
pable of becoming a very active ferment. The effect of its
action is to change starch into dextrine, then into sugar, and
finally into lactic acid. Its most important influence, how-
ever, is exerted upon the gluten. This it transforms into
ammonia, a peculiar brown substance which gives the color
to the bread, and a new ferment capable of transforming su-
gar into lactic acid. These changes may take place to some
extent in bread which is inferior in quality from being al-
lowed to ferment too long, so that the acidulous action pre-
dominates. Brown bread is not as light as bread of the best
quality, and contains less gluten, a considerable quantity
having undergone transformation into ammonia and brown
coloring matter. It is not so easily digested, from the fact
that it is less easily penetrated by the gastric juice. Yery
fresh bread, particularly if it be warm, is less easily digested
than after it has been allowed to become " stale." In this
state the process of mastication compresses it into pasty
masses which are not easily penetrated by the digestive
fluids ; while bread eaten a few hours after baking is disinte-
grated by mastication, and absorbs the fluids of the mouth in

96 ALIMENTATION.

large quantity. The importance of porosity in improving
the digestibility of bread has been illustrated by experiments
on animals. Dr. Hammond caused a dog, in which he had
established a gastric fistula, to eat successively equal weights
of vesiculated and compressed bread. The first was di-
gested in two hours and fifteen minutes, and the latter, in
three hours and thirty-five minutes.1

In the manufacture of good bread it is absolutely neces-
sary to render it porous by the generation of gas in the dough
before baking ; but this may be effected without fermenta-
tion. Unfermented or aerated bread may be made by mix-
ing carbonate of soda with the flour and adding hydrochloric
acid in the water, or by using water charged with carbonic
acid. The use of bread made in this way is simply a ques-
tion of taste.

Flour simply mixed with water and baked, called in this
form ship-bread, sea-biscuit, hard-tack, etc., will keep almost
indefinitely. It requires thorough mastication, and is not
so easily digested as ordinary bread, but apparently all the
nutritive principles are preserved. The other forms of bread,
rolls, muffins, etc., are simply articles of luxury, and do not
differ much in their nutritive properties from ordinary bread.
The various forms of cake are made of flour, with the addi-
tion of butter, lard, eggs, sugar, and sometimes dried fruits.

Although bread has been called the staff of life, it seems
incapable by itself of supplying for an indefinite period all the
nutritive demands of the human organism. The same may be
said, however, of every single article of food, whether it be-
long to the animal or vegetable kingdom ; for man requires
a much greater variety of alimentary principles than the in-
.ferior animals. While it is possible that life might be barely
sustained on bread and water, experience with regard to this
diet in prisons and elsewhere has demonstrated that it is in-
capable of maintaining the body in full vigor. That this is

1 HAMMOND, Treatise on Hygiene, Philadelphia, 1883, p. 519.

LEGUMINOUS KOOTS, LEAVES, SEEDS, ETC. 97

probably due to a deficiency in variety of alimentary prin-
ciples is shown by Magendie's experiments on dogs :

" A dog eating ad libitum of white bread, made of pure
wheat, and drinking at will ordinary water, does not live be-
yond fifty days ; he dies at the end of that time, with all the
signs of gradual exhaustion above noted.

" A dog eating exclusively of military brown bread (de
'munition) lives very well, and the health is not altered in
any way." ]

Brown bread is not perhaps absolutely so nutritive as
white ; but as it contains a certain quantity of the bran, it
presents a greater variety of nutritive principles, and seems,
from the above experiments, better calculated, as the single
article of food, to meet the demands of the system.

The paste, which in Italy takes the place, to a great ex-
tent, of bread, in the form of macaroni, vermicelli, etc., is a
highly nutritious preparation. The real Italian article is
made of the hard wheat with only the outer covering re-
moved, and contains a much greater proportion of gluten
and oily matters than ordinary bread. It is made to assume
its peculiar form by forcing the thick paste through per-
forated metallic plates. It is then dried and may be kept for
any length of time. Presenting, as it does, a larger propor-
tion of nitrogenized and fatty matters, it is more nutritious
than bread. Payen estimates the nutritive value of 100 parts
as equal to 151'5 parts of white bread.3

Leguminous Roots, Leaves, Seeds, etc.

The remaining vegetable articles of food do not demand
extended consideration, as the alimentary principles which
they contain are little different from those already de-
scribed. They are highly useful, however, as furnishing that
variety of diet, the necessity of which cannot be too fully in-

1 MAGENDIE, Precis jZlemeniaire de Physiologic, Paris, 1836, tome Si., p. 504.
3 Op. cit., p. 294.

98 ALIMENTATION.

sisted upon ; but as far as quantity and variety of essential
alimentary principles are concerned, there is no one of them
which is comparable to wheaten bread.

The ordinary potato is by far the most important of the
leguminous roots. It undoubtedly forms a larger part of our
vegetable food than any other article except wheat ; and of all
vegetables it is the one that becomes least distasteful from
continued use. In Ireland, the potato forms the greatest part
of the diet of the poorer classes, but those who live almost
exclusively upon it are not well nourished. It is generally
taken after the starch-granules have been disintegrated and
its general structure softened by cooking ; but in a raw state
it has been found very useful in scurvy, or where there is a
scorbutic tendency, particularly in armies. A study of the
proximate composition of the potato shows that it cannot of
itself be capable of maintaining the organism in full vigor,
on account of its great deficiency in nitrogenized and fatty
materials :

Pfoximate Composition of the Potato?

Water , 66'875

Starch and amylaceous fibre 30-469

Albumen O503

Gluten 0-055

Fat , 0-056

Gum 0-020

Asparagin 0'063

Extractive 0-921

Chloride of potassium 0-176

Silicate, phosphate, and citrate of iron, manganese, alumina, soda, pot- \

ash, and lime (of these, potash and citric acid are the prevailing > O'SIS

ingredients) ;

Free citric acid 0'047

100-000

The sweet potato, so largely used in the United States,
contains more water, and about half the proportion of starch

1 PEREIRA, Treatise on Food and Diet, New York, 1843, p. 180.

LEGUMINOUS BOOTS, LEAVES, SEEDS, ETC. 99

contained in the ordinary potato, and from four to five per
cent, of sugar.

Some other articles belonging to the class of legumi-
nous roots, the beet-root for example, contain a large
proportion of sugar, but ordinarily they are deficient in
starch1 as compared with the potato, and present but a
small quantity of nitrogenized matter. Many, like the
parsnip, salsify, carrots, etc., contain a certain amount of vol-
atile oil and peculiar flavoring matter. Onions and garlics
are remarkable for the presence of a large quantity of vola-
tile oil. These articles are specially craved when the system
is suffering from a deficiency of vegetable food, and are very
useful in scurvy.

The young and tender shoots of asparagus are highly
prized for their exquisite flavor. The volatile principle of
this vegetable is eliminated by the kidneys, giving a very
peculiar odor to the urine.

Many green leaves and leaf-stalks, such as cabbage,
cauliflower, lettuce, celery, chiccory, cresses, etc., are used
as food, but chiefly as articles of luxury. They contain a
large proportion of water, and little or no starch. Sauer-
~kraut) which is so commonly used in Germany, is made
by packing cut cabbage with salt under a heavy pressure,
and allowing it to remain for several weeks until it has under-
gone the acetic acid fermentation. It is then stewed and
eaten with meats.

The leguminous seeds possess a certain degree of impor-
tance as alimentary substances. Those most commonly used
are the different varieties of beans and peas. They contain
a large proportion of starchy matter, and a considerable
quantity of vegetable caseine. When dried they constitute
an important part of many army-rations. They must be
considered as highly nutritious, though inferior to most of
the cereal grains, notwithstanding that they contain a large

1 For a list of vegetables containing little or no starch, see p. 57.

100 ALIMENTATION.

proportion of nitrogenized matter. They contain a very
small proportion of the phosphates.

The ripe fruits are characterized by the presence of
large quantities of sugar, mallic and citric acid and their
combinations, pectine or vegetable jelly, and by the absence
of starch. They are used as articles of luxury and contribute
somewhat to the variety in diet, but they are not very im-
portant as alimentary substances. The various melons are
particularly grateful and refreshing, but they contain a very
small proportion of solid or nutritive matters.

Condiments and Flavoring Articles.

The refinements of modern cookery involve the use of
numerous articles which cannot be classed as alimentary
principles. Pepper, capsicum, vinegar, mustard, spices, and
articles of this class, which are so commonly used, with the
various compound sauces, have no decided influence on nu-
trition, except in so far as they promote the secretion of the
digestive fluids. Common salt, however, as we have already
seen, is very important, and has already been considered
under the head of inorganic alimentary principles. The
various flavoring seeds and leaves, truffles, mushrooms, etc.,
have no physiological importance except as rendering ar-
ticles of food more palatable.

CHAPTEK IY.

DEINKS. QUANTITY AND QUALITY OF FOOD.

Water — Alcohol — Distilled liquors — Wines, malt liquors, etc. — Coffee — Tea —
Chocolate — Quantity and variety of food necessary to nutrition — Necessity
of a varied diet.

Water.

WATEK, one of the most important of the proximate
principles of the organism, and found in every tissue and
part without exception, is introduced with all kinds of
food, and is the basis of all drinks. Its functions in the
economy have already been fully considered. As a rule, it is
taken in greater or less quantity in nearly a pure state.
Although, as a drink, water should be colorless, odorless,
and nearly tasteless, it always contains more or less of saline
and other matters in solution, with a certain quantity of air.
The air and gases may be evolved by boiling or removing
the atmospheric pressure. Pure water (HO) does not exist
in nature. Even rain-water always contains salts, and fre-
quently a little ammonia and organic matter. The Croton
water supplied to the city of New York, contains 4*16 grains
of solid matter to the gallon.1 The waters of the mineral
springs, which are so abundant in parts of this country, are
very rich in saline constituents, and generally contain a no-
table quantity of carbonic acid ; but the consideration of their
properties does not belong to physiology. Water charged
with carbonic acid under pressure, called soda water, or in

*Dr. LEE, in PEREIRA, on Food and Diet, p. 43, note.

102 ' ALIMENTATION.

France eau de Seltz, is a very common drink, and its excel-
lence depends on the thoroughness with which the gas has
been washed and freed from impurities. Sea-water may be
rendered fit for drinking by distillation and agitation with
air. Apparatus for thus supplying pure water is generally
found in well-appointed sea-going vessels.

The demand on the part of the system for water is reg-
ulated, to a certain extent, by the quantity discharged from
the organism, and this is subject to great variations. The
quantity taken as drink also depends very much on the con-
stitution of the food as regards the water which enters into
its composition.

Alcohol.

All distilled and fermented liquors and wines contain a
greater or less proportion of alcohol. As these are so gener-
ally used as beverages, and as the effects of their excessive
use are so serious, the influence of alcohol upon the organ-
ism has become one of the most important questions con-
nected with alimentation. In the discussion of this subject
it is not proposed to enter into the great moral questions
involved, but to consider, from a purely physiological point
of view, the immediate and remote influences of the various
alcoholic beverages upon nutrition and the animal functions.
Some alcoholic beverages influence the functions solely
through the alcohol which they contain; while others, as
beer and porter, with a comparatively small proportion of al-
cohol, contain a considerable quantity of solid matters which
may act as alimentary principles.

Alcohol (C4H602), from its composition, is to be classed with
the non-nitrogenized principles, more especially the fats, in
which the hydrogen and oxygen do not exist in the proportion
to form water. We have seen that sugar and fat are essen-
tial to proper nutrition and undergo in the organism impor-
tant changes. Alcohol is capable of being absorbed and
taken into the blood ; and it becomes a question of great

DKINKS. QUANTITY AND QUALITY OF FOOD. 103

interest to determine whether it be consumed in the econo-
my, or whether it be discharged unchanged by the various
emunctories. Many volatile and other substances are known
to be thus exhaled or discharged from the body. The vola-
tile principle of the onion may be recognized in the expired
air for some time after the article has been taken into the
stomach. Various ingested matters are discharged unchanged
in the urine. Common salt, when taken in excess, is thus re-
moved. But all the ordinary nitrogenized and non-nitrogen-
ized principles in the ingesta are consumed, undergo certain
transformations in nutrition, and are never discharged, in
health, in the form in which they entered.

Alcohol has long since been recognized in the expired air
after it has been taken into the stomach ; and late researches
have confirmed the earlier observations with regard to its elim-
ination in its original form, and have shown that after it has
been taken in quantity, it exists in the blood and all the tissues
and organs, particularly the liver and nervous system.1 Lal-
lemand, Perrin, and Duroy have noted the elimination of
alcohol by the lungs, skin, and kidneys.2 The experiments
by which these results were arrived at are very satisfactory.
They show that even when a very small quantity of alcohol
is taken it may be detected in the blood and is eliminated
for many hours, progressively diminishing in quantity from
the period of its ingestion, until it is all removed or destroyed.
In a man after taking " an ordinary quantity of alcoholic
drink" (a little more than a quart of red wine containing

1 It was formerly a question considerably discussed whether alcohol exists in
the brain, or in the fluid found in the ventricles, in intoxicated persons. This
was settled by Percy, who found alcohol in the brain, liver, and sometimes in
the urine, in dogs poisoned with alcohol, and in men who had died after excessive
drinking. In these experiments, the presence of alcohol was determined by dis-
tillation, the distilled substances being inflammable, and capable of dissolving
camphor. — PERCY, Prize Thesis. An Experimental Inquiry concerning the Pres*
ence of Alcohol in the Ventricles of the Brain, etc., London, 1839.

a LALLEMAND, PERRIN, et DUROY, Du R&le de VAlcool el des Anesthesiques dans
rOrganisme, Paris, 1860.

104: ALIMENTATION.

ten per cent, of alcohol), " the Jungs eliminated alcohol for
eight hours, and the kidneys for fourteen hours." *

The question now arises whether the alcohol be elimi-
nated in totality, or wThether it be in part removed in this
way, and in part destroyed in the system. This it is difficult
to answer with positiveness. It has been shown that a certain
amount of alcohol may be transformed into acetic acid in
the stomach, but this quantity is insignificant, and the experi-
ments of the observers above quoted show that it does not take
place in the general system. The view that alcohol undergoes
combustion or oxidation is based upon theoretical and not
upon any experimental considerations ; and the fact that this
substance is always eliminated, even when taken in minute
quantity, and that its elimination continues for a consider-
able time, gradually diminishing, render it probable that all
that is taken into the body is removed. The practical diffi-
culties in the way of collecting all the exhalations, espe-
cially those from the skin and lungs, are so great, that this
cannot, as yet, be demonstrated experimentally.2

1 Op. tit., p. 121.

Percy detected alcohol in five ounces of urine taken from a man in a condi-
tion of intoxication, by first distilling over three drachms of a colorless liquid,
subjecting this to a second distillation in which one drachm passed over, which
was agitated in a test-tube with subcarbonate of potassa. He thus obtained a
clear supernatant stratum, which dissolved camphor and burned with a blue
flame (op. cit., p. 105). There can be hardly any doubt but that the kidneys al-
ways eliminate a certain quantity of alcohol when this substance finds its way
into the circulation.

2 A recent English writer, Dr. Anstie, does not accept ths observations of Lal-
lemand, Perrin, and Duroy as showing that, in all probability, alcohol taken into
the alimentary canal is eliminated as alcohol, and is removed in totality by the
various emunctories. The experiments of Dr. Anstie are not on a very extended
scale, and, as far as they go, rather support than controvert the opinion of the
French observers. He found that even after small doses of alcohol had been
taken, the presence of this substance could be determined in the urine and in
the pulmonary and cutaneous exhalations. (Stimulants and Narcotics, Philadel-
phia, 1865, p. 358 et seg.) It must be remembered, however, that the total
elimination by the lungs and skin of watery vapor, which is much less volatile
than alcohol, is enormous, although, by the skin especially, its quantity in a lim-

ALCOHOL. 105

In the present state of our knowledge, alcohol cannot be
regarded as an aliment ; but it is undoubtedly capable of
profoundly affecting the nervous system, and, in its passage
through the organism, has a decided influence on the process
of nutrition.

Taken in moderate quantity, alcohol generally produces a
certain amount of nervous exaltation, which passes off as it
is eliminated. In some individuals the mental faculties are
sharpened by alcohol, while in others they are blunted.
There is nothing, indeed, more variable than the immediate
effects of alcohol on different persons. In large doses the
effects are the well-known phenomena of intoxication, delir-
ium, more or less anaesthesia, coma, and sometimes, if the
quantity be excessive, death. As the rule, the mental ex-
altation produced by alcohol is. followed by reaction and de-
pression, except in debilitated or exhausted conditions of the
system, when the alcohol seems to supply a decided want.

The views of physiologists concerning the influence of a
moderate quantity of alcohol on the nervous system are
somewhat conflicting. That it may temporarily give tone
and vigor to the system, when the energies are unusually
taxed, cannot be doubted; but this effect is not produced
in all individuals. The constant use of alcohol may create
an apparent necessity for it, producing a condition of the
system which must be regarded as pathological.

The immediate effects of the ingestion of a moderate
quantity of alcohol, -continued for a few days, are decided.
It notably diminishes the exhalation of carbonic acid and the
discharge of other excrementitious principles, particularly
urea. These facts have long since been experimentally
demonstrated;1 but recently, very important observations

ited period is apparently small, and is estimated with great difficulty. It is by
these avenues particularly that we should suppose that so volatile a principle as
alcohol would be chiefly thrown off.

1 The influence of alcohol on the exhalation of carbonic acid has already been
considered (see vol. i., Keapiration) ; and its effect on the quantity of urea dis-
charged will be more fully treated of in connection with excretion.

106 ALIMENTATION.

have been made by Dr. Hammond, which bear more particu-
larly on the influence of this agent on nutrition. It is well
known that by carefully regulating the diet, exercise, etc., the
weight of the body, in a healthy man, can be maintained for
a time at a standard which may be taken as normal. Under
these conditions the mind is clear, the appetite good, the
food is relished, and every function appears to be in normal
operation. Dr. Hammond — after a number of experiments
in which he established, in his own person, the conditions
which would maintain the weight at a fixed point, and hav-
ing noted the exact quantities of the excretions and the ex-
halations from the lungs — took at breakfast, luncheon, and
dinner four drachms of alcohol diluted with an equal quan-
tity of water, and continued this for five days. The results
we give in his own words :

" Thus, after the use of sixty drachms of alcohol in five
days, my weight is seen to have increased from an average
of 226*40 pounds to an average of 226*85 pounds, being *45
of a pound difference. The carbonic acid and vapor of water
in the expired air had respectively decreased 1,324*50 and
196*51 grains; the fssces, 1*22 ounces ; the urine, 3*43 ounces;
the urea, 87*19 grains ; the chlorine, 37*59 grains ; the phos-
phoric acid, 24*47 grains, and the sulphuric acid, 13*40 grains.
The free acid and uric acid, especially the former, were so
slightly affected as to render it probable that the alcohol
had exercised no influence upon them." 1 During this time
there was some disturbance of the general health. The
pulse was increased in frequency, there was headache, and
the mental faculties were not so clear as on the days when
no alcohol was taken.

The second series of experiments was for the purpose of
ascertaining the influence of alcohol wThen the body was
losing weight from an insufficiency of food. It wTas found
that by reducing the daily quantity of meat from sixteen to

1 HAMMOND, The Physiological Effects of Alcohol and Tobacco upon the Hu-
man System. — Physiological Memoirs, Philadelphia, 1863, p. 48.

ALCOHOL. 107

ten ounces, and the bread from eighteen to twelve ounces,
the loss of weight was well marked. This diet was con-
tinued for five days, with the effect of reducing the weight
from 226*73 to 225*34: pounds; a daily average loss of *28
of a pound. At the end of the five days, twelve drachms ol
alcohol were taken daily, as before, and continued for five
days. The decrease in weight was not only arrested, but
there was an increase of *03 of a pound daily. The quantity
of food fully satisfied the appetite, and " all the functions
of the body were performed with regularity ; " while during
the five days preceding the use of alcohol, there was unusual
exhaustion after exertion, " and the desire for food was very
much increased, and was never completely appeased by the
quantity ingested." J

In a third series of experiments, an excess of food was
taken. This increased the weight by an average of "22 of a
pound daily ; there was constant headache, indisposition to
exertion, loss of appetite, etc. For five days succeeding this,
twelve drachms of alcohol were taken daily, with the effect
of diminishing the quantities of excretions and exhalations,
aggravating the unpleasant symptoms produced by the
excess of food, and increasing the average gain in weight
from *22 to *31 of a pound.

These experiments demonstrate the actual immediate in-
fluence of alcohol upon nutrition, under the conditions above
given ; for the observer was a young man, in perfect health,
and not accustomed to the constant use of alcoholic bever-
ages. The observations were apparently conducted with
great exactness, and continued sufficiently long to afford
definite results ; of which the following are some of the most
important :

The ingestion of a moderate quantity of alcohol retards
the destructive assimilation of the tissues ; for the diminution
in the quantity of the excretions in the experiments of Ham-
mond was too long continued to admit of the theory that the

1 Loc. ciL

108 ALIMENTATION.

effete products were simply retained in the blood and not
removed by the proper organs.

It is also demonstrated that when the system is so nour-
ished that the weight is stationary, the moderate ingestion
of alcohol, for a short time, will cause an increase in weight
corresponding with the diminution in the quantity of the
excretions ; with, however, some disturbance of the general
health and the mental faculties.

The loss of weight consequent upon insufficiency of food
may be temporarily arrested and the unpleasant symptoms
relieved by the use of alcohol in moderate quantity.

The gain in weight following over-ingestion of food is
increased and the disturbance of the system aggravated by
the use of alcohol.

If the observations showing the elimination of alcohol
from the system be taken as conclusive, it is evident that
this agent influences nutrition in its passage through the
organism, and that its immediate effects are of a transitory
nature. It cannot be considered as an alimentary principle,
or as capable of supplying the place of articles which are
actually assimilated. The proper amount of mental and
physical exercise, tranquillity of the nervous system, and all
circumstances which favor the vigorous nutrition and de-
velopment of the organism physiologically increase, rather
than diminish, the amount of the excretions, correspondingly
increase the demand for food, and, if continued, are of per-
manent benefit. Alcohol, on the other hand, diminishes the
activity of nutrition. If it be long continued, the assimila-
tive powers of the system become so weakened that the
proper quantity of food cannot be appropriated, and alcohol
is craved to supply a self-engendered want. The organism
may, in many instances, be restored to its physiological con-
dition by discontinuing the use of alcohol ; but it is generally
some time before the nutritive powers become active, and
alcohol, in the mean time, seems absolutely necessary to
existence.

ALCOHOL. 109

Under ordinary conditions, when the organism can be
adequately supplied with food, alcohol is undoubtedly inju-
rious. "When the quantity of food 'is insufficient, alcohol may
supply the want for a time, and temporarily restore the
powers of the body; but the effects of its continued use,
conjoined with insufficient nourishment, show that it cannot
take the place of assimilable matter. These effects are too
well known to the physician, particularly in hospital-prac-
tice, to need further comment.

Notwithstanding these undoubted physiological facts,
alcohol, in some form, is used by almost every people on the
face of the earth — civilized or savage. Whether this be in
order to meet some want occasionally felt by and peculiar to
the human organism is a question upon which physiologists
have found it impossible to agree* That alcohol, at certain
times, taken in moderation, soothes and tranquillizes the
nervous system and relieves exhaustion dependent upon
unusually severe mental or physical exertion, cannot be
doubted. It is by far too material a view to take of exist-
ence, to suppose that the highest condition of man is that
in which the functions, possessed in common with the lower
animals, are most perfectly performed. Inasmuch as tem-
porary insufficiency of food, gi*eat exhaustion of the nervous
system, and various conditions in which alcohol seems to be
useful, must of necessity often occur, it is hardly proper that
this agent should be utterly condemned ; but it is the article,
par excellence, which is liable to abuse, and the effects of
which on the mind and body, when taken constantly in ex-
cess, are most serious.

Although alcohol imparts a genial warmth when the sys-
tem is suffering from excessive cold, it is not proven that it
enables men to endure a very low temperature for a great
length of time. This end can be effectually accomplished
only by an increased quantity of food. The testimony of Dr.
Hayes, the Arctic explorer, is very strong upon this point.
He says : " While fresh animal food, and especially fat, is ab-

110 ALIMENTATION.

solutely essential to the inhabitants and travellers in Arctic
countries, alcohol is, in almost any shape, not only completely
useless but positively injurious. * * * Circumstances
may occur under which its administration seems necessary ;
such, for instance, as great prostration from long-continued
exposure and exertion, or from getting wet; but then it
should be avoided, if possible, for the succeeding reaction is
always to be dreaded ; and, if a place of safety is not near at
hand, the immediate danger is only temporarily guarded
against, and becomes, finally, greatly augmented by reason
of decreased vitality. If given at all, it should be in very
small quantities frequently repeated, and continued until a
place of safety is reached. I have known the most unpleas-
ant consequences to result from the injudicious use of whis-
key for the purpose of temporary stimulation, and have also
known strong able-bodied men to have become utterly inca-
pable of resisting cold in consequence of the long-continued
use of alcoholic drinks." '

It is not demonstrated that alcohol increases the capacity
to endure severe and protracted bodily exertion. Its influ-
ence as a therapeutic agent, in promoting assimilation in cer-
tain conditions of defective nutrition, in relieving shock and
nervous exhaustion, in sustaining the powers of life in acute
diseases characterized by rapid emaciation and abnormally
active destructive assimilation, etc., is undoubted; but the
consideration of these questions does not belong to physi-
ology.

Distilled Liquors. — The variety of distilled liquors con-
sumed in civilized countries is very great. Brandy, the
product of the distillation of wine, is the one most esteemed,
and, in therapeutics, generally produces most positively and
promptly the beneficial effects of alcohol. As the liquor

1 HAYES, Observations upon the Relations existing between Food and the Capo-
birdies of Men to resist Low Temperatures. — American Journal of the Medical
Sciences, July, 1859, p. 117.

WINES, MALT-LIQTJOKS, ETC. Ill

most highly prized, it is naturally most subject to adultera-
tion and imitations.

Various other liquors distilled from the fermented prod-
ucts of grains or fruits are in common use. The most
important of them are whiskey, which is made from rye,
corn, wheat, or oats ; gin, made from various grains rectified
with turpentine and juniper; rum, made from molasses;
and apple or peach-brandy, made from the juices of these
fruits. Liquors are also sometimes made from the potato.

As a rule, the distilled liquors contain a little more than
fifty per cent., by volume, of alcohol, specific gravity, *825.
Alcohol is undoubtedly more injurious taken in this form
than in any other, as its quantity is large, and it is unmixed
with the tonic and nutritive principles contained in many
wines and malt-liquors. The gravest effects of the abuse of
alcoholic beverages, which are, unfortunately, so common in
countries where spirit-drinking prevails, are almost unknown
where the light wines are the ordinary drink of all classes.

Wines, Malt-Liquors, etc. — The fermented juice of the
grape furnishes an almost infinite variety of wines. These
are called full-bodied or light, as they contain more or
less alcohol. The stronger wines, such as port, madeira,
and sherry, contain from fifteen to twenty-five per cent, of
alcohol; while the lighter wines, such as claret, sauterne,
and hock, contain from ten to fifteen per cent. Every dis-
tinct variety of wine contains peculiar flavoring and aro-
matic principles, either characteristic of the grape or pro-
duced in the process of manufacture.

As wine contains a variety of principles, chiefly non-
nitrogenized matters, with organic acids and salts, its effects
upon the system are somewhat different from those of alcohol
or the distilled liquors. The following are the constituents
found, in variable proportions, in most wines : 1

1 PEREIUA, A Treatise on Food and Diet, New York, 1843, p. 202.

112 ALIMENTATION.

Constituents of Wine.
Water,
Alcohol,

Bouquet (volatile oil ? an ether ?),

Sugar,

Gum,

Extractive matter,

Gluten (except when tannin is present),

Acetic acid,

Bitartrate of potash,

Tartrate of potash and alumina (in German wines),

Sulphate of potash,

Chlorides of potassium and sodium,

Tannin, ) ,.

' (. (i

.

Coloring matter of the husk, \

Carbonic acid (in champagne and other effervescing wines).

As the proportion of alcoliol in many wines is quite
small, it is only when they are taken in quantity that its
disturbing effects upon the system are manifested. "Wines
supply, on the other hand, many important saline prin-
ciples, and some have a very decided action as tonics. It
must be borne in mind, however, that wines are very often
adulterated and imitated. They then contain ordinary spirit,
with extraneous coloring and flavoring principles which are
often highly injurious.

The sparkling wines are made from the juice of the grape
treated in such a way as to increase the production of car-
bonic acid ; a process which generally involves the addition
of glucose. The exhilarating properties of the carbonic acid,
added to those of the alcohol, render these wines more rap-
idly stimulating in their effects than other beverages which
contain an equal amount of alcohol. Champagne is often
the best diffusible stimulant that can be employed, in certain
diseases which demand prompt and vigorous support of the
vital powers.

WINES, aiALT-LIQTJORS, ETC. 113

In many parts of the United States, the manufacture of
wine from native grapes has assumed considerable impor-
tance. The Catawba wines, of Ohio, the California, and
the JSTorth Carolina wines have become quite celebrated.
Though these are of rich flavor and possess many good
qualities, it will be many years before wine can be produced
in this country equal in delicacy to the products of the vine-
yards of the old world.

Malt-liquors (beer, ale, porter, etc.) are prepared from
malted barley, flavored with hops. They contain a very
small quantity of alcohol ; in the milder beverages of this
class, the proportion being from one to four per cent., and in
the stronger from six to eight per cent. All varieties con-
tain a certain proportion of carbonic acid, which is particu-
larly abundant when the liquor has been kept in bottles.
The principal difference between malt-liquors and other
alcoholic beverages is that they contain a large proportion
of saccharine and nitrogenized matters. These are in such
quantity that malt-liquors possess considerable importance
as alimentary articles. In therapeutics, the bitter principle
of the hop acting as a tonic, the nutritive action of the solid
ingredients, and the stimulant effect of the alcohol, combine to
render the malt-liquors very valuable in debilitated conditions
of the system, or in the convalescence from exhausting diseases.

The following is the composition of good French beer,
like that generally called Strasbourg beer. The heavy
English and Scotch ales and porter generally contain a
larger proportion of alcohol :

Composition of Seer.1

Water 947'00

Alcohol 4-50

Dextrine, glucose, and substances of this class 41 '40

Nitrogenized substances 6*26

Mineral salts 1'84

Bitter principle, aromatic essence (quantity not determined).

1,000-00

1 PATEN, Precis Theorique et Pratique des Substances Alimentaires, Paris,
8

114 ALIMENTATION.

Light and agreeable beverages made from the juice of
apples or of pears are in common use. "When first made, cider
contains the organic acids and salts of the fruit, with a large
quantity of sugar. It is then called sweet cider, and con-
tains little or no alcohol. After it has fermented, the sugar
in part or entirely disappears, alcohol is formed in consider-
able quantity (from 5*21 to 9*87 per cent.),1 and the liquor
is then called hard cider. Under proper conditions, ace-
tous fermentation soon converts the liquid into vinegar.
During the process of fermentation, carbonic acid is produced
in large quantity, and if the liquor be made of good apples
and be bottled at the proper time, its flavor is little inferior
to that of ordinary champagne. The effects of cider upon
the system are substantially those of the light white wines.

Perry, a beverage manufactured to a considerable extent in
England from pears, is little used in this country. When new
it is sweeter than cider, and possesses the flavor of the pear.
By fermentation a liquor is produced, resembling cider in most
regards, but containing about fifty per cent, more alcohol.

Coffee.

Coffee is an article consumed daily by many millions
of human beings, in all quarters of the globe. In armies
it has been found indispensable, enabling men on mod-
erate rations to perform an amount of labor which would
otherwise be impossible. After exhausting efforts of any
kind there is no article which relieves the overpowering
sense of fatigue so completely as coffee. Army-surgeons say
that at night, after a severe march, the first desire of the sol-
dier is for coffee, hot or cold, with or without sugar, the only
essential being a sufficient quantity of the pure article. This
has been the universal experience in the late civil war ; the
rations of coffee issued by the United States Government be-

1865, p. 462. In copying this table an evident error (957 instead of 947 of wa-
ter) has been corrected.

1 DUNGLISON, Medical Lexicon, Philadelphia, 1857, p. 984.

COFFEE. 115

ing abundant and pure, though not, of course, of the quality
possessing the most delicate flavor. Almost every one can
bear testimony from personal experience of the effects of
coffee in relieving the sense of fatigue after mental or bodily
exertion, and in increasing the capacity for labor, especially
mental, by producing wakefulness and clearness of intellect.
From these facts the importance of coffee, either as an ali-
mentary article, or as taking the place, to a certain extent,
of aliment, is apparent.

Except in persons who, from idiosyncracy, are unpleas-
antly affected by it, coffee, taken in moderate quantity and
at proper times, produces an agreeable sense of tranquillity
and comfort, with, however, no disinclination to exertion,
either mental or physical. Its immediate influence upon the
system, which is undoubtedly stimulant, is peculiar, and is
not followed by reaction or unpleasant after-effects. Habitual
use makes coffee almost a necessity, even in those who are
otherwise well nourished and subject to no extraordinary men-
tal or bodily strain. Taken in excessive quantity, or in those
unaccustomed to it, particularly when taken at night, it pro-
duces persistent wakefulness. These effects are so well known
that it is often taken for the purpose of preventing sleep.

Experimental researches have shown that the use of coffee
permits a reduction in the quantity of food, in workingmen
especially, much below the standard which would otherwise
be necessary to maintain the organism in a proper condition.
In the observations of De Gasparin upon the regimen of the
Belgian miners, it was found that the addition of a quantity
of coffee to the daily ration enabled them to perform their
arduous labors on a diet which was even below that found
necessary in prisons and elsewhere where this article was not
employed.1 Numerous experiments have shown that coffee

1 The diet of the miners of Cbarleroi, where these observations were made,
was evidently deficient in nitrogenized matter, the quantity of nitrogen which it
represented, aside from the coffee, being but 14*82 grammes (228 '7 grains). But
on this diet, with the addition of coffee, De Gasparin found that the vital energies

116 ALIMENTATION.

diminishes the absolute quantity of urea discharged by the
kidneys.1 In this respect, as far as has been ascertained, the
action of coffee is like that of alcohol, and may reasonably
be supposed to retard destructive assimilation ; with the im-
portant difference that it is followed by no unfavorable after-
effects, and can be used in moderation for an indefinite time
with advantage.

Dr. Hayes, the Arctic explorer, in comparing the proper-
ties of alcohol and tea and coffee in enabling men to resist
cold and endure hardships in the Arctic regions, gives the
highest praise to the latter articles. In comparing tea and
coffee he says that " Dr. Kane's parties, after repeated trial,
took most kindly to coffee in the morning and tea in the
evening. The coffee seemed to last throughout the day, and
the men seemed to grow hungry less rapidly after taking it
than after drinking tea, while tea soothed them after a day's
hard labor, and the better enabled them to sleep. They both
operated upon fatigued and over-taxed men like a charm,
and their superiority over alcoholic stimulants was very
marked." 2 These facts are highly interesting, for there could
be no better opportunity of testing the real value of such

and muscular power were well developed. The following was the ordinary diet,
reduced to ounces av. and grains. There was an abundance of good white bread,
but the quantity of meat was evidently insufficient :

Coffee 1 oz. 34 grains.

Ohiccory. 1 oz. 34 "

Milk a little less than half a pint.

Bread 35 oz. 121 grains.

Butter 2" 51 "

Green vegetables 26 " 200 "

Meat 2 " 251 "

DE GASPARIN, Note sur le Regime des Mineurs Beiges. — Comptes Rendus,
Paris, 1850, tome xxx., p. 400.

1 HAMMOND, Urological Contributions. — American Journal of the Medical
Sciences, January, 1855 ; and JOHNSTON, Chemistry of Common Life, New York,
1859, vol. i., p. 168, note.

2 HAYESJ op. cit. — American Journal of the Medical Sciences, July, 1859, p.
118.

COFFEE. 117

agents than in men thus subjected to intense cold and extra-
ordinary hardships.

A study of the composition of coffee shows a considerable
proportion of what must be considered as alimentary matter.
The following is the result of the latest analyses by Payen :

Composition of Coffee.

Cellulose 34-

"Water (hygroscopic) 12'

Fatty substances 10 to 13-

Glucose, dextrine, indeterminate vegetable acid 15-500

Legumine, caseine, etc 10'

Ghlorolignate of potash and caffeine 3'5 to 5'

Nitrogenized organism 3'

Free caffeine 0*800

Concrete, insoluble essential oil O'OOl

Aromatic essence, of agreeable odor, soluble in water 0'002

Mineral substances : potash, magnesia, lime, phosphoric, silicic, and sul-
phuric acid and chlorine 6'697

100-000

The above is the composition of raw coffee, but the
berry is never used in that form, being always subjected to
torrification before an infusion is made. The roasting should
be conducted slowly and gently until the grains assume a
chestnut-brown color. During this process the grains are
considerably swollen, but they lose from sixteen to seventeen
per cent, in weight. A peculiar aromatic principle is also
developed. If the torrification be pushed too far, much
of the agreeable flavor is lost, and an acrid empyreumatic
principle is produced. An infusion of fifteen hundred grains
of roasted and ground coffee in about a quart of boiling wa-
ter, the infusion made by simple percolation, contains about
three hundred grains of the soluble principles. According
to Payen, this contains about one hundred and forty grains
of nitrogenized matters, and one hundred and fifty-three
grains of fatty, saccharine, and saline substances. There is
every reason to suppose that these principles are assimilated ;

1 Op. dt., p. 414.

118 ALIMENTATION.

and an infusion of coffee, with milk and sugar, presents>
therefore, a considerable variety and quantity of alimentary
matter. The peculiar stimulant effects of coffee are prob-
ably due to the caffeine and volatile oil.

The varieties of coffee in common use are very numerous.
The best in the market is the Arabian, or Mocha. The
characteristic aroma of coffee is developed by age, which im-
proves to a very great extent some of the inferior varieties.
The best Mocha coffee requires, after it is gathered, three or
four years to ripen. In this country and in Europe, coffee
is prepared for use by simply making an infusion of the
roasted and pulverized berry in hot water, either by boiling
or by simple percolation. The aromatic and active prin-
ciples are best extracted by the latter process. They are but
slightly soluble in cold water.

An adulteration of coffee, so common as to demand the
consideration of the physiologist, consists in the addition of
the chiccory-root, cut into small pieces, dried, roasted, and
pidverized. This gives a rich brown color to the infusion,
and its flavor, not unlike that of coffee itself, is not disagree-
able. It has, however, none of the stimulating effects before
described ; but is used purposely, to a great extent, by many
who do not seek for the peculiar stimulant influence of the
pure article.

In the countries where coffee is grown, the leaves of the
shrub, roasted and made into an infusion, are quite com-
monly used. Their effects upon the system are similar to
those of coffee, and it is said that the natives prefer the leaves
to the berry.1

Tea.

An infusion of the dried and prepared leaves of the tea-
plant is perhaps as common a beverage as coffee, and taking
into consideration its immense consumption in China and
Japan, is actually used by a greater number of persons. Its

1 JOHNSTON, Chemistry of Common Life, New York, 1859, vol. i., p. 157.

TEA.

119

effects upon the system are similar to those of coffee, but are
generally not so marked. Ordinary tea, taken in moderate
quantity, like coffee, relieves fatigue and increases mental
activity, but does not usually induce such persistent wake-
fulness.

It is unnecessary to describe all the varieties of tea in com-
mon use. There are, however, certain .varieties, called green
teas, which present important differences, as regards compo-
sition and physiological effects, from the black teas, which
are more commonly used. The following is a comparative
analysis of these two varieties by Mulder : 1

Composition of Tea.

CONSTITUENTS.

CHINESE.

JAVANESE.

Hyson.

Congou.

Hyson.

Congou.

0-79
2-22
0-28
2-22
8-56
17-80
0-43
22-80

23-60
3-00
17-08

0-60
1-84

3-64
7-28
12-88
0-46
19-88
1-48
19-12
2-80
28-32

0-98
3-24
0-32
1-64
12-20
17-56
0-60
21-68

20-36
3-64
18-20

0-65
1-28

2-44
11-08
14-80
0-65
18-64
1-64
18-24
1-28
27-00
~97-70~
5-36

Chlorophylle

Wax

Theine

Apotheme2

Extract obtained by hydrochloric acid

Fibrous matter

Salts included in the above . .

98-78
5-56

98-30
5-24

100-42
4-76

Both tea and coffee possess peculiar organic principles.
The active principle of tea is called theine, and the active prin-
ciple of coffee, caffeine. These have been found to be iden-
tical in ultimate composition ; their formula being C8H5O2]^"2.
As they are supposed to be particularly active in producing

1 PEREIRA, Food and Diet, New York, 1843, p. 190.

Hyson is a green tea, and Congou is black. With regard to the proportion
of theine in teas, there is considerable difference of opinion. Payen (op. dt., p.
427) quotes the analyses of Peligot, which give from 2-34 to 3 parts per 100. He
also found from 20 to 30 per cent, of nitrogenized matter.

a A pecuh'ar brown deposit which slowly takes place in vegetable extracts
(Berzelius).

120 ALIMENTATIOlSr.

the peculiar effects upon the nervous system which are
characteristic of both tea and coffee, there is good reason
to suppose that they are also identical in their physiological
effects. Theine (or caffeine) exists in greater proportion in
tea than in coffee ; but, as a rule, much more soluble matter
is employed in the preparation of coffee, which may account
for its more marked effects upon the system.

Green tea, especially in those unaccustomed to its use,
frequently produces nervous tremor, wakefulness, and dis-
turbed sleep — when sleep can be obtained — palpitations, and
other disturbances usually termed nervous. In some persons
these unpleasant effects may be overcome by habit; and
many constantly use a mixture of equal parts of black and
green tea with no unpleasant effects. The peculiar effects
of green tea are attributed to the volatile oil, which it con-
tains in great abundance.1

Tea is prepared for drinking by rapidly making an infu-
sion of the leaves with hot water. The aroma is nearly
destroyed by boiling. The proportion generally used is about
three hundred grains of tea to a quart of water. The tea is
first covered with boiling water, and allowed to steep, or
" draw," for from ten to fifteen minutes, in a warm place ;
and boiling water is then added in the quantity desired.
Green tea, treated in this way, yields about twenty per cent,
of soluble matters, and black tea, about twenty-three per
cent.8

Chocolate.

Chocolate is made from the seeds of the cocoa-tree, roast-
ed, deprived of their husks, and ground with warm rollers into
a pasty mass with sugar, flavoring substances being sometimes

1 It is a question still undecided whether green tea be actually a distinct
variety, or whether it differ from black only in the mode of curing. The leaves
of green tea are smaller and younger when gathered, and are cured more rapid-
ly than black tea.

2 PA YEN, op. tit., p. 428.

CHOCOLATE. 121

added. It is then made into cakes, cut into small pieces,
or scraped to a powder, and boiled with milk or milk and
water, when it forms a thick, gruel-like drink, which is
highly nutritive, and has some of the exhilarating properties
of coffee and tea. Beside containing a large proportion of
iiitrogenized matter resembling albumen, the cocoa-seed is
particularly rich in fatty matter, and contains a peculiar
principle, theobromine, analogous to caffeine and theine,
which is supposed to possess similar physiological properties.
The following is a late analysis by Payen1 of the cocoa-
seeds freed from the husks, but not roasted. Torrification
has the effect of developing the peculiar aromatic principle,
and moderating the bitterness, which is always more or less
marked :

Composition of Kernels of Cocoa.

Fatty matter (cocoa-butter) 48 to 50

Albumen, fibrin, and other nitrogenized matter 21 " 20

Theobromine 4 " 2

Starch (with traces of saccharine matter) 11 " 10

Cellulose 3 " 2

Coloring matter, aromatic essence traces.

Mineral substances 3 to 4

Hygroscopic water 10 to 12

100 100

It is evident, from the above table, that cocoa with milk
and sugar, the ordinary form in which chocolate is taken,
must form a very nutritious mixture. Taken with a little
bread, it readily relieves hunger, and supplies nearly all the
principles absolutely necessary to nutrition. Its influence as
a stimulant, supplying the place of matter which is directly
assimilated and retarding destructive assimilation, is depend-
ent, if it exists at all, upon the theobromine ; but its- stimu-
lating properties are slight as compared with coffee and tea.

A drink called cocoa is sometimes made of the seeds
roasted entire and mixed with a little starchy matter, but

1 Ibid., p. 400.

122 ALIMENTATION.

this is not so delicate in flavor as chocolate. A brown mu-
cilaginous infusion is sometimes made of the husks (shells).
This has a slight chocolate-flavor, but does not possess the
nutrient properties of the kernels.

Quantity and Variety of Food necessary to Nutrition.

The inferior animals, especially those not subjected to the
influence of man, regulate by instinct the quantity and kind
of food which they consume. The same is true of man dur-
ing the earliest periods of his existence ; but later in life, the
diet is variously modified by taste, habit, climate, and what
may be termed artificial wants. It is usually a safe rule to
follow the appetite with regard to quantity, and the tastes—
when they are not manifestly vitiated or morbid — with regard
to variety. The cravings of nature indicate when to change
the form in which nourishment is taken ; and that a sufficient
quantity has been taken is manifested by a sense, not exactly
of satiety, but of evident satisfaction of the demands of the
system. During the first periods of life, the supply must be
a little in excess of the actual loss in order to furnish mate-
rials for growth. During the latter periods, the quantity of
nitrogenized matter assimilated is somewhat less than the
loss ; but in adult age, the system is maintained at a tolera-
bly definite standard by the assimilation of material about
equal in quantity to that which is discharged in the form of
excretions.

Although the loss of substance by destructive assimilation
creates and regulates the demand for food, it is an important
fact, never to be lost sight of, that the supply of food has a
very great influence upon the quantity of the excretions.
As an illustration of this, we may take the influence of food
upon the exhalation of carbonic acid ; l and this is but an
example of what takes place with regard to the other excre-
tions. The quantity of the excretions is even more strikingly
modified by exercise, which, within physiological limits, in-

1 See vol. i., Respiration, p. 435 e*. seq.

NECESSARY QUANTITY AND VARIETY OF FOOD. 123

creases the vigor of the system, provided the increased quan-
tity of food required be supplied.

While a certain amount of waste of the system is inevi-
table, it is a conservative provision of nature, that when the
supply of new material is diminished life is preserved — not,
indeed, in all its vigor — by a corresponding reduction in the
quantity of excretions ; and, in the same way, the vital forces
are retained after complete deprivation of food much longer
than if destructive assimilation proceeded always with the
same activity.

As regards the quantity of food necessary to maintain the
system in proper condition, it is evident that this must be
greatly modified by habit, climate, the condition of the mus-
cular system, age, sex, etc., as well as idiosyncrasies.

The daily loss of substance which must be supplied by
material introduced from without is very great.1 A consider-
able portion of this discharge takes place by the lungs, and the
mode of introduction of gaseous principles to supply part of this
waste belongs to the subject of respiration. The most abun-
dant discharge which is compensated by absorption from the
alimentary canal is that of water, both in a liquid and vapor-
ous condition. The entire quantity of water daily removed
from the system has been estimated at about four and a half
pounds ; 2 and, assuming that there is no evidence of its pro-
duction in the organism, an equal quantity must necessarily
be introduced. The quantity which is introduced in the form
of drink varies with the character of the food. When the
solid articles contain a large proportion of water, the quan-
tity of drink may be diminished ; and it is possible, by taking
a large proportion of the watery vegetables, to do without
drink altogether.8

1 Prof. Dalton estimates that the daily discharges from the body, including
the pulmonary and cutaneous exhalations, amount to a little more than seven
pounds avoirdupois. (Human Physiology, Philadelphia, 1864, p. 363.)

a DALTON, op. cit., p. 70.

8 Prof. Chas. A. Lee gives a number of examples of persons who were not in
the habit of taking water, except that which is contained in the food ; but in these

124: ALIMENTATION.

There is no article the consumption of which is so much
a matter of habit as water, any excess which may be taken
being readily removed by the kidneys, skin, and lungs. Prof.
Dalton estimates the daily quantity necessary for a full-grown,
healthy male at fifty-two fluid ounces, or 3*38 Ibs. avoirdupois.1

The quantity of solid food necessary to the proper nour-
ishment of the body is shown by estimating the solid matter
in the excretions ; and the facts thus ascertained correspond
very closely with the quantity of material which the system
has been found to actually demand. The estimates of Payen,
the quantity of carbon and of nitrogenized matter in a dry
state being given, are generally quoted and adopted in works
on physiology. According to this observer, the following are
the daily losses of the organism :

Carbon (or its equiv.) j Inspiration, 3,868-5 grs. ) 7 ( }

1 I Excretions, 926-04 " )
Nitrogenized substances (with 308-68 grs. of Nit.) 2,006-42 grs. ( 4-58 oz. av.)

6,800-96 grs. (15-51 oz. av.)

From this he estimates that the normal ration, supposing
the food to consist of lean meat and bread, is as follows : 3

Nitrogenized Substances. Carbon.

Bread 15,434 grs. (35-27 oz.)=l,080-38 grs. and 4,630-2 grs.

Meat 4,412-12 grs. (10-09 oz.)= 930'05 grs. and 485-55 grs.

19,846-12 grs. (45-36 oz.) 2,010-43 grs. 6,115-75 grs.

This daily ration, which is purely theoretical, is shown
by actual observation to be nearly correct. Prof. Dalton
eays : " From experiments performed while living on an ex-
cases the diet consisted of vegetables of the most succulent kind. He mentions
one case in which water was not t^ken for more than a year — during that
time the subject not experiencing the sensation of thirst more than two or three
times, and then after copious perspiration from working in hot weather. (PE-
SEIRA, Treatise on Food and Diet, edited by CHARLES A. LEE, M. D., New York,
1843, p. 277.)

I0p. cit.,p. 113.

2 PAYEN, Substances Alimentaires, Paris, 1865, p. 482. The weights have
been reduced from grammes to troy grains, and ounces av.

NECESSARY QUANTITY AND VAEIETY OF FOOD. 125

elusive diet of bread, fresh meat, and butter, with coffee and
water for drink, we have found that the entire quantity of
food required during twenty-four hours by a man in full
health and taking free exercise in the open air, is as follows :

Meat ................................. 16 ounces, or I'OO Ib. avoirdupois.

Bread ................................ 19 " " 1-19 " "

Butter or fat .......................... 3$ " " 0'22 " "

Water ................................ 52 fluid oz. " 3-38 " "

That is to say, rather less than two and a half pounds of solid
food, and rather over three pints of liquid food." 1

Bearing in mind the great variations in the nutritive de-
mands of the system in different persons, it may be stated, in
general terms, that in an adult male, from ten to twelve
ounces of carbon, and from four to five ounces of nitrogen-
ized matter (estimated dry) are discharged from the organ-
ism, and must be replaced by the ingesta ; and this demands
a daily consumption of from two to three pounds of solid
food ; the quantity of food depending, of course, greatly on
its proportion of solid, nutritive principles.2

It is undoubtedly true that the daily ration has frequent-
ly been diminished considerably below the physiological
standard in charitable institutions, prisons, etc. ; but when
there is complete inactivity of body and mind, this pro-
duces no other effect than that of slightly diminishing the
weight and strength. The system then becomes reduced
without any actual disease, and there is simply a diminished
capacity for labor. But in the alimentation of large bodies

. dt.

2 The correspondence between the absolute quantities of nitrogen and carbon
contained in the excretions, and their proportions in the food necessary to sus-
tain the system, is truly remarkable. In elaborating this idea Payen (op. cit., p.
488) has prepared a table giving the proportions of nitrogen, carbon, fatty mat-
ter, and water in a hundred different articles, comprising nearly all the important
varieties of food. This table is of great value as showing the nutritive power of
different articles entering into the dietaries of armies, charitable institutions, etc.,
when the quantity of food for a large number of persons must be regulated by
some fixed standard.

126 ALIMENTATION.

of men, subjected to exposure, and frequently called upon
to perform great labor, the question of food is of vital im-
portance, and the men collectively are like a powerful ma-
chine in which a certain quantity of material must be fur-
nished in. order to produce the required amount of force.
This important physiological fact is most strikingly exem-
plified in armies ; and the history of the world presents few
examples of warlike operations in which the efficiency of
the men has not been impaired by insufficient food. In the
Crimea, this was often the case with both the English and
French troops. The ration of the British soldier, at home
stations, is sixteen ounces of bread, or twelve ounces of bis-
cuit, and sixteen ounces of meat. This gives 6*48 ounces of
carbon, and 3*62 ounces of nitrogenized matter ; 1 a quantity
which is acknowledged to be insufficient; but the soldier is
expected to purchase certain articles for himself, such as
coffee, sugar, fresh vegetables, etc. In the Crimea it was
found necessary to deviate from the regular ration, and allow
to each soldier twenty-four ounces of bread and sixteen N
ounces of meat, with rice, sugar, coffee, and a little spirit.2

The United States army-ration is the most generous in
the world ; and the result has been that, in the recent civil
war, scurvy and other diseases which are usually so rife in
armies subject to the exposure and fatigue incident to grand
military operations have been comparatively rare. In some
of the long and arduous campaigns of the war, the marches
made by large bodies of troops and the labor performed
showed an amount of endurance heretofore unknown in mil-
itary history. The excellent physical condition of the men
was further evidenced by the remarkable percentage of re-
coveries after serious wounds and surgical operations, and

1 Calculated from Pay en's table (lot: cit.). The bread is assumed to contain
the same principles as the white, French bread, and the meat to contain bone
equal to one-fifth of its weight.

2 HAMMOND, A Treatise on Hygiene, with special reference to the Military Ser-
vice, Philadelphia, 1863, p. 561.

NECESSABY QUANTITY AND VAUIETY OF FOOD. 127

the slight prevalence of the ordinary diseases, except those
of malarial origin.

The following is the army ration of the United States : * •

Daily Ration of the United States Soldier.

Bread or flour 22 ounces.

Fresh or salt beef (or pork or bacon, 12 oz.) 20

Potatoes (three times per week) 16

Rice 1-6

Coffee (or tea 0-24 oz.) 1-6 «

Sugar 2-4 "

Beans 0-64 gill.

Vinegar 0'32 "

Salt 0-16 "

The bread, meat, and potatoes in the above ration contain
9 '28 of carbon and 4*68 of nitrogenized matter; in addi-
tion to which are the alimentary principles contained in the
rice, beans, sugar, and coffee, with the peculiar stimulant
effect of the coffee. The United States soldier does not re-
ceive alcohol unless exposed to extraordinary privations or
fatigue.

• The influence of diet upon the capacity for labor was well
illustrated by a comparison of the amount of work accom-
plished by English and French laborers in 1841, on a rail-
road from Paris to Rouen. The French laborers engaged on
this work were able at first to perform only about two-thirds
of the labor accomplished by the English. It was suspected
that this was due to the more substantial diet of the English,
which proved to be the fact ; for when the French laborers
were subjected to a similar regimen, they were able to ac-
complish an equal amount of work.2

In all observations of this kind, and they are very nu-
merous, it has been shown that an animal diet is much more
favorable to the development of the physical forces than one
consisting mainly of vegetables.

1 HAMMOND, op. cit., p. 564.
,2LoNGET, Traite de Physiologic, Paris, 1861, tome i., p. 89.

128 ALIMENTATION.

Climate has an important influence on the quantity of
food demanded by the system. It is generally acknowl-
edged that the consumption of all kinds of food is greater in
cold than in warm climates, and almost every one has experi-
enced in his own person a considerable difference in the ap-
petite at different seasons of the year. Travellers' accounts of
the quantity of food taken by the natives of the frigid zone are
almost incredible. They speak of men consuming over a hun-
dred pounds of meat in a day ; and a Russian admiral, Sarit-
cheff, mentions an instance of a man who, in his presence, ate
at a single meal a mess of boiled rice and butter weigh-
ing twenty-eight pounds.1 Though it is difficult to regard
these statements with entire confidence, the general opinion
that the appetite is greater in cold than in warm climates is
undoubtedly well founded. Dr. Hayes, the Arctic explorer,
states, from his personal observation, that the daily ration of
the Esquimaux is from twelve to fifteen pounds of meat,
about one-third of which is fat. On one occasion he saw an
Esquimau consume ten pounds of walrus-flesh and blubber
at a single meal, which lasted, however, several hours. The
continued low temperature he found had a remarkable effect
on the tastes of his own party. With the thermometer rang-
ing from — 60° to — 70° Fahr. there was a continual craving
for a strong animal diet, particularly fatty substances. Some
members of the party were in the habit of drinking the
contents of the oil-kettle with evident relish.2

Necessity of a Varied Diet.

In considering the nutritive value of the various aliment-
ary principles, the fact that no single one of them is capable
of supplying all the material for the regeneration of the or-
ganism has frequently been mentioned. The normal appetite,

1 COCHRANE, A Pedestrian Journey through Russia, etc. — CONSTABLE'S Miscel-
lany, Edinburgh, 3829, vol. i., p. 194.

2 HAYES, An Arctic Boat-Journey, Boston, 1860, pp. 257-259, and American
Journal of the Medical Sciences, July, 1859, p. 114 et seq.

NECESSITY OF A VAEIED DIET. 129

which is our best guide as regards the quantity and the
selection of food, indicates that a varied diet is necessary to
proper nutrition. This fact is also exemplified in a marked
degree in long voyages and in the alimentation of armies,
when, from necessity or otherwise, the necessary variety of
aliment is not presented. Analytical chemistry fails to show
why this change in alimentary principles is necessary, or in
what the deficiency in a single kind of diet consists ; but it
is nevertheless true that after the organic constituents of
the organism have appropriated the nutritious elements of
particular kinds of food for a certain time, they lose the
power of inducing the catalytic changes necessary to proper
nutrition, and a supply of other material is imperatively de-
manded. This fact is particularly well marked when the
diet consists in great part of salted meats, though it is also
the case when any single variety of fresh meat is constantly
used. After long confinement to a diet restricted as regards
variety, a supply of other material, such as fresh vegetables,
the organic acids, and articles which are called generally
anti-scorbutics, becomes indispensable ; otherwise the modifi-
cations in nutrition and in the constitution of the blood in-
cident to the scorbutic condition are sure to be developed.

It is thus apparent that an adequate quantity and proper
quality of food is not all that is demanded in alimentation ;
and those who have the responsibility of regulating the diet
of a large number of persons must bear in mind the fact that
the organism demands considerable variety. Fresh vegeta-
bles, fruits, etc., should be taken at the proper seasons. It is
almost always found, when there is of necessity some same-
ness of diet, that there is a general craving for particular ar-
ticles, and these, if possible, should be supplied. This was
frequently exemplified in the late war. At times when the
diet was necessarily somewhat monotonous, there was an al-
most universal craving for onions and raw potatoes, which
were found by the surgeons to be excellent anti-scorbutics.

In those who supply their own food the question of vari-

130 ALIMENTATION.

etj of diet generally regulates itself; and in institutions, it is
a good rule to follow as far as possible the reasonable tastes
of the inmates. In individuals, particularly females, it is not
uncommon to observe marked disorders in nutrition attribu-
table to want of variety in the diet as well as an insufficient
quantity of food, as a matter of education or habit.

The physiological effects of a diet restricted to a single
alimentary principle, or a few articles, have been pretty
closely studied both in the human subject and in the inferior
animals. Magendie long since demonstrated that animals
subjected to a diet composed exclusively of non-nitrogenized
articles died in a short time with all the symptoms of
inanition. The same result followed in dogs confined to
white bread and water ; but these animals lived very well on
the brown military bread, as this contains a greater variety
of alimentary principles.1 Facts of this nature were multi-
plied by the "Gelatine commission," and the experiments
were extended to nitrogenized substances, and articles con-
taining a considerable variety of alimentary principles.2 In
these experiments it was shown that dogs could not live on
a diet of pure musculine ; the appetite failing entirely, from
the forty-third to the fifty-fifth day.3 They were nourished
perfectly well by gluten, which, as we have seen, is com-
posed of a number of different alimentary principles.

Among the conclusions arrived at by this commission

1 MAGENDIE, Precis Elementaire de Physiologic, Paris, 1817, tome ii., p. 390
et seq. The fourth edition of this work (Paris, 1836, p. 504) contains the experi-
ments of Magendie upon the comparative nutritive power of white and of brown
bread. In 1827, Tiedemann and Gmelin published an account of experiments on
geese which were confined to an exclusive diet respectively of gum, sugar, starch,
and coagulated white of egg. All of them died : the one fed with gum, on the
sixteenth day ; the one fed with sugar, on the twenty-first day ; the two fed with
starch, on the twenty- fourth and twenty-seventh days, respectively; and the one
fed with white of egg, on the twenty-sixth day. — (Redierches Experimeniales,
Physiologiques et Chimiques, sur la Digestion, Paris, 1827, Second Partie, p. 266.)

2 The results of the inquiry into the nutritive value of gelatine have already
been considered. See page 49.

3 Comptes Rendus, Paris, 1841, p. 275.

NECESSITY OF A VARIED DIET. 131

which bear particularly on the questions under consideration,
were the following :

"Gelatine, albumen, fibrin, taken separately, do not
nourish animals except for a very limited period and in a
very incomplete manner. In general, these substances soon
excite an insurmountable disgustr to the point that animals
prefer to die of hunger rather than touch them.

" The same principles artificially combined and rendered
agreeably sapid by seasoning are accepted more readily and
longer than if they were isolated, but ultimately they have
no better influence on nutrition, for animals that take them,
even in considerable quantity, finally die with all the signs
of complete inanition.

" Muscular flesh, in which gelatine, albumen, and fibrin
are united according to the laws of organic nature, and when
they are associated with other matters, such as fat, salts, etc.,
suffices, even in very small quantity, for complete and pro-
longed nutrition." 1

In Burdach's treatise on physiology, is an account of some
interesting experiments by Ernest Burdach on rabbits, show-
ing the influence of a restricted diet upon nutrition. Three
young rabbits from the same litter were experimented upon.
One was fed with potato alone, and died on the thirteenth
day with all the appearances of inanition. Another fed on
barley alone, died in the same way during the fourth week.
The third was fed alternately day by day with potato and
barley, for three weeks, and afterward with potato and bar-
ley given together. This one increased in size and was per-
fectly well nourished.2

In 1769, long before any of the above-mentioned experi-
ments were performed, Dr. Stark, a young English physiol-
ogist, fell a victim at an early age to ill-judged experiments
on his own person on the physiological effects of different

1 Op. dt., p. 282.

2 C. F. BURDACH, Traitc de Physiologic, traduit par JOURDAN, Paris, 1841,
tome ix., p. 249.

132 ALIMENTATION.

kinds of food. He lived for forty-four days on bread and
water, for twenty-nine days on bread, sugar, and water, and
for twenty-four days on bread, water, and olive-oil ; until
finally his constitution became broken, and he died from the
effects of his experiments.1

The late experiments of Dr. Hammond on his own person
on the nutritive value of albumen, starch, and gum show the
impossibility of sustaining life, even with a substance so nu-
tritious, when combined with other principles, as albumen ;
and thus confirm, in the human subject, the observations of
Magendie and others on the inferior animals.2

1 These remarkable observations were collected and published after the death
of Dr. Stark, by Dr. James Carmichael Smyth. (The Works of the late WILLIAM
STARK, M. D., London, 1798.) In commencing his observations on diet, Dr.
Stark says that " Dr. B. Franklin, of Philadelphia, informed me that he himself,
when a journeyman printer, lived a fortnight on bread and water, at the rate of
10 Ibs. of bread per week, and that he found himself stout and hearty with this
diet," (p. 92.)

2 HAMMOND, Experimental Researches relative to the nutritive value and physio-
logical effects of Albumen, Starch, and Gum, when singly and exclusively used as
Food. — Transactions of the American Medical Association, 1857.

CHAPTEE Y.

DIGESTION — PREHENSION AND MASTICATION.

General arrangement of the digestive apparatus — Prehension of solids and
liquids — Mastication — Physiological anatomy of the organs of mastication —
Enamel of the teeth — Dentine — Cement — Pulp-cavity — Arrangement of the
teeth — Anatomy of the maxillary bones — Temporo-maxillary articulation —
Muscles of mastication — Muscles which depress the lower jaw — Action of the
muscles which elevate the lower jaw and move it laterally and antero-pos-
teriorly — Action of the tongue, lips, and cheeks in mastication — Summary of
the process of mastication.

General Arrangement of the Digestive Apparatus.

THE inorganic alimentary principles are, with few excep-
tions, introduced in the form in which they exist in the
blood, and require no preparation or change before they are
absorbed; but the organic nitrogenized principles are al-
ways united with more 'or less matter possessing no nutritive
properties, from which they must be separated ; and even
when pure they always undergo certain changes before they
become part of the great nutritive fluid. The non-nitro-
genized principles also undergo changes in constitution or in
form preparatory to absorption. With the varied forms in
which food is presented to different animals, we find great
differences in the arrangements of the digestive apparatus;
from the simple pouch with a single orifice, which constitutes
the entire digestive system of many of the infusorial animal-
cules, to the immense length of intestine, with its numerous
glandular appendages, found in the mammalia. In the
higher classes of animals, great differences exist in the

134 DIGESTION.

anatomy of the digestive organs, particularly as regards the
length and capacity of the alimentary canal. In the carni-
vora, in which the food contains comparatively little in-
digestible residue, the intestine is but three or four times
the length of the body (i. e. from the mouth to the anus), and
the colon, which receives the residue of digestion, is of small
capacity ; while in the herbivora, in which the bulk of food,
compared with its nutritious principles, is enormous, there
are frequently four distinct cavities to the stomach, and the
intestine is ten, twelve, and in some (the sheep) twenty-eight
times the length of the body, with a colon of very large size.
The food of man is derived from both the animal and vege-
table kingdom, and in length and capacity, the alimentary
canal is between that of the carnivora and the herbivora, be-
ing from six to seven times the length of the body.1

A full meal probably occupies from two to four hours in
its digestion, this depending, of course, on the kind of food,
the fineness of its comminution by mastication, etc.2 The

1 CUVIER, Lemons d1 Anatomic Comparee, Paris, 1835, tome iv., Deuxieme Par-
tie, p. 173. In this work is given a long and elaborate table of measurements of
the intestines as compared with the length of the trunk ; the measurements of the
intestines, including all between the pylorus and the anus, and the measurement
of the trunk, in the mammalia, extending from the mouth to the anus. Taking the
latter measurement in the human subject as from two and a quarter to two and
a half feet, the length of the intestinal canal would be, in general terms, from fif-
teen to eighteen feet. This is much less than the estimate generally given in works
on anatomy, in which the measurements given vary between twenty and thirty feet.
In the natural condition of the parts, the estimate of Cuvier is perhaps pretty near
the truth, for the intestines are very extensible, and are much longer when de-
tached from the mesentery and stretched out, than they are in situ ; but the
standard of measurement, i. e., the length of the body, is very indefinite.

2 This estimate is roughly made from the celebrated experiments of Dr. Beau-
mont in the case of Alexis St. Martin (Experiments and Observations on the Gas-
tric Juice and the Physiology of Digestion, Plattsburg, 1833). In one of these ob-
servations, after a meal of roast- turkey, potatoes, and bread, the stomach was
found empty in two and a half hours (p. 171). The stomach was found empty
one hour and thirty-five minutes after a breakfast of venison-steak, cranberry-
jelly, and br^ad (p. 147). From a large number of observations, Dr. Beaumont
concludes " that the time required for the disposal of a moderate meal of the
fibrous parts of meat, with bread, etc., is from three to three and a half hours."

GENERAL ARRANGEMENT OF THE DIGESTIVE APPARATUS. 135

matters taken into the stomach consist generally of all1 varie-
ties of alimentary principles, and they are exposed to certain
mechanical processes in the mouth and alimentary canal, and
to the action of various secreted fluids.

In the mouth, the food is divided, as the occasion de-
mands, by the incisor teeth, and is then passed, by the action
of the cheeks and tongue, between the molars, where it is sub-
jected to mastication. During this process it is mixed with
the various fluids which compose the saliva, and becomes more
or less coated with the tenacious secretions of the mucous
follicles of the buccal cavity. It is, or should be, reduced
in the mouth to a pultaceous mass, with which the saliva,
particularly that from the parotid gland, is thoroughly incor-
porated; while the secretion of the submaxillary and the
sublingual gland, being more viscid, has a greater tendency
to coat the exterior.

By the action of the tongue, the alimentary bolus, after
mastication, is passed back to the pharynx, where, by the
successive action of the constrictor muscles, it is forced into
the cesophagus. This tube leads from the pharynx to the
stomach, and is provided with thick muscular walls, by the
contraction of which the food is passed into this cavity, which
serves at once as a receptacle for the food, and an important
active organ in digestion.

The stomach is covered externally by the general perito-
neal covering of the abdominal organs. It is provided with
a mucous membrane, which secretes the gastric juice and ab-
sorbs the water with inorganic and other principles in solu-
tion. The stomach also has muscular walls, composed of un~

In this he only has reference to the action of the stomach •, but the food passes
gradually from this organ into the intestinal canal, and the digestion is then
completed very rapidly. In many instances, after a good breakfast, Dr. Beau-
mont found the stomach empty in less than two hours ; but it sometimes required
more than four hours to dispose of the food taken at dinner. In later observa-
tions on St. Martin, in 1856, by Prof. F. G. Smith, of Philadelphia, it is stated
that food was never found in the stomach for more than two hours. — (Experi-
ences sur la Digestion. — Journal de la Physiologic, Paris, 1858, tome i., p. 146.),

136 DIGESTION.

striped muscular fibres arranged in two principal layers.
Nearly all the principles contained in food are modified by the
gastric juice, and some are completely liquefied and absorbed
in the stomach. By the action of the gastric juice, the food,
comminuted and incorporated with the fluids of the mouth,
is further reduced to a pultaceous mass, which was formerly
called the chyme ; the muscular movements of the stomach
turning it over and over, so that it may become thoroughly
incorporated with the fluids. These movements have a ten-
dency to force the food, as it becomes sufficiently liquefied,
into the small intestine; and a large collection of circular
muscular fibres, called sometimes the pyloric muscle, stands
at the pylorus as a guard, allowing the liquid portions to
pass gradually through, but sending back the larger masses
to be further acted upon in the stomach.

By these movements, a great portion of the food, prepared
by the action of the stomach, is slowly forced into the small
intestine. This tube, from fifteen to twenty feet in length, is
covered with peritoneum and loosely bound to the spinal
column by the mesentery, which is formed of the two folds
of the peritoneum, and is sufficiently long to allow of free
movements of the intestines over each other and in the ab-
dominal cavity, except the first few inches, where it is pretty
firmly attached to the posterior abdominal wall. The small
intestine commences by a dilated portion eight or ten
inches in length, called the duodenum. The remainder is
divided into the jejunum and the ileum. The former em-
braces the upper two-fifths of the intestine, but there is no
distinct line of separation between it and the ileum. The
mucous membrane lining the small intestine is thick, pro-
vided with an immense number of villi, and, particularly in
the upper portion, is thrown into transverse folds which are
called the valvulse conniventes. These disappear in the lower
part of the ileum. They are peculiar to the human subject.
Thickly set in the upper part of the duodenum, and scattered
through its lower portion and the upper part of the jejunum,

PREHENSION OF SOLIDS -AND LIQUIDS. 137

are small compound follicles called the glands of Brunn ;
and throughout the whole of the intestine are simple, blind
follicles, called the follicles of Lieberktihn. These glandu-
lar organs secrete the intestinal juice. As the food passes
from the stomach into the intestine, it imbibes the bile and
pancreatic juice, which are poured into the duodenum, as
well as the intestinal juice.

Between the mucous membrane of the small intestine
and the peritoneum are two layers of unstriped muscular
fibres ; by the progressive peristaltic action of which, the
food is passed slowly on toward the large intestine. The
alimentary principles, liquefied and prepared by digestion,
are gradually absorbed by the blood-vessels of the intestinal
mucous membrane, and by the lacteals.

The indigestible residue of the food is passed by peris-
taltic action into the large intestine. This portion of the ali-
mentary canal is from four to six feet in length ; and, like the
small intestine, has a peritoneal, mucous, and muscular coat.
Under ordinary conditions the large intestine is not con-
cerned in digestion. It simply retains the residue of food,
with certain excrementitious substances, until its contents
are expelled by the act of defecation.

Prehension of Solids and Liquids.

The different modes of prehension form a very interest-
ing part of the physiology of digestion in the inferior ani-
mals; but in the human subject, the process is so simple
and well known that it demands nothing more than a pass-
ing mention. The mechanism of sucking in the infant and
of drinking is a little more complicated. In sucking, the lips
are closed around the nipple, the velum pendulum palati is
applied to the back of the tongue so as to close the buccal
cavity posteriorly, and the tongue, acting as a piston, pro-
duces a tendency to a vacuum in the mouth, by which the
liquids are drawn in with considerable force. This may be
done independently of the act of respiration, which is neces-

138 DIGESTION.

sarily arrested only during deglutition ; for the mere act of
suction has never any thing to do with the condition of the
thoracic walls. The mechanism of drinking from a vessel is
essentially the same. The vessel is inclined so that the lips
are kept covered with the liquid, and are closed around the
edge. By a gentle sucking action the liquid is then intro-
duced. This is the ordinary mechanism of drinking; but
sometimes the head is thrown back and the liquid is poured
into the mouth, as in " tossing off" the contents of a small
vessel, as a wine-glass.1

In drinking from a spoon, or in taking hot liquids,
or when it is desired to introduce but a small quantity at a
time, the liquid is drawn into the mouth with an act of
inspiration. In this process the lips are not covered by the
liquid, as in ordinary drinking, and it enters the mouth with
a more or less audible sound.

Mastication.

In the human subject, mechanical division of food in the
mouth is neither so completely and laboriously effected as in
the herbivora, particularly the ruminants, nor is the process
so rapid and imperfect as in the carnivora. In order that
digestion may take place in a perfectly natural manner, it is
necessary that the food, as it is received into the stomach,
should be so far comminuted and incorporated with the flu-
ids of the mouth as to be readily acted upon by the gastric
juice ; otherwise stomach-digestion is prolonged and difficult.
Non-observance of this physiological law is a frequent cause
of what is generally called dyspepsia. In animals that do
not masticate, as some which live exclusively on flesh, the
process of stomach-digestion is much more prolonged than

1 Any one can easily convince himself that the ordinary mechanism of drink-
ing is by suction, by simply analyzing his own movements during this act. The
vessel is inclined so as simply to cover the lips, and not sufficiently to pour the
liquid into the mouth ; and the fact that a suction force is exerted by the mouth
becomes very evident when the attention is directed to it.

MASTICATION. 139

in the human subject, even when the diet is the same ; and
it is found that while man must, as a rule, take food two or
three times in the day, the carnivorous animals are generally
best nourished when food, in proper quantity, is taken but
once in the twenty-four hours. In the carnivora, the propor-
tionate quantity of food is greater than in man, and digestion
is much more prolonged.

The comparative anatomy of the organs of mastication
makes it evident that the human race is designed to live on a
mixed diet ; but experience has shown that man can be nour-
ished for an indefinite period on a diet composed exclusively
of either animal or vegetable principles.

Physiological Anatomy of the Organs 'of Mastication.

In the adult, each jaw is provided with sixteen teeth, all
of which are about equally well developed. The canines, so
largely developed in the carnivora, but which are rudiment-
ary in the herbivora, and the incisors and molars, so per-
fectly developed in the herbivora, are, in man, of nearly the
same length. Each tooth presents, for anatomical descrip-
tion, a crown, a neck, and a root or fang. The crown is
that portion which is entirely uncovered by the gums ; the
root is that portion embedded in the alveolar cavities of the
maxillary bones; and the neck is the portion, sometimes
slightly constricted, situated between the crown and the root,
covered by the edge of the gum. Thin sections of the teeth
show that they are composed of several distinct structures.

Enamel of the Teeth. — The crown is covered by the enam-
el, which is by far the hardest structure in the economy.
This is white and glistening, and is thickest on the lower
portion of the tooth, especially over the surfaces which,
from being opposed to each other on either jaw, are most
exposed to wear. It here exists in several concentric layers.
The incrustation of enamel becomes gradually thinner tow-
ard the neck, where it ceases. Microscopical examination

140 DIGESTION.

shows that the enamel is made up of pentagonal or hexago-
nal rods, one end resting npon the subjacent structure, and
the other, when there exists but a single layer of enamel, ter-
minating just beneath the cuticle of the teeth. The hardness
of the enamel varies in different persons. In some it is so soft
that in middle life it becomes worn away from the opposing
surfaces, and occasionally the teeth are worn down almost to
the gums ; while in others the enamel remains over the crown
of the tooth even in old age.

The exposed surfaces of the teeth are still further pro-
tected by a membrane, from 7TrJ- ¥p- to TJ Vo-o- of an inch in
thickness, closely adherent to the enamel, called the cuticle
of the enamel. This delicate membrane may be demon-
strated in thin sections of young teeth by the addition, under
the microscope, of weak hydrochloric acid. The acid at-
tacks the enamel, producing little bubbles of gas which press
out the membrane from the edge of the preparation, and
thus render it apparent. The cuticle presents a strong resist-
ance to reagents, and undoubtedly is very useful in protect-
ing the teeth from the action of acids which may find their
way into the mouth.

Dentine. — The largest portion of the teeth is composed
of a peculiar structure called dentine, or ivory. In many re-
spects, particularly in its composition, this resembles bone ;
but it is much harder, and does not possess the lacunge
and canaliculi which are characteristic of the true osseous
structure. The dentine bounds and encloses the central cav-
ity of the tooth, extending in the crown to the enamel, and
in the root to the cement. It is formed of a homogeneous
fundamental substance, which is penetrated by an immense
number of canals radiating from the pulp-cavity toward the
exterior. These are called the dentinal tubules or canals.
They are from -zj^-o-o to rsio-o- of an mch m diameter, with
walls of a thickness a little less than their calibre. Their
course is slightly wavy or spiral. Commencing at the pulp-

DESCRIPTIVE ANATOMY OF THE TEETH. 141

cavity, into which these canals open by innumerable little
orifices, they are found to branch and occasionally anasto-
mose, their communications and branches becoming more
numerous as they approach the external surface of the tooth.
The canals of largest diameter are found next the pulp-cav-
ity, and they become smaller as they branch. The structure
which forms the walls of these tubules is somewhat denser than
the intermediate portion, which is sometimes called the inter-
tubular substance of the dentine ; but in some portions of the
tooth, the tubules are so numerous that their walls touch
each other, and there is, therefore, no inter-tubular substance.
Near their origin and near the peripheral terminations of the
dentinal tubules, are sometimes found solid globular masses
of dentine, called dentine-globules, which irregularly bound
triangular or stellate cavities of very variable size. These
cavities have been considered as lacunae, like the lacunae of
true bone ; but this view is not held by the best and most
recent observers. Sometimes these cavities are very numer-
ous, and form regular zones near the peripheral termination
of the tubules. The dentine is sometimes marked by con-
centric lines, indicating a lamellated arrangement. In the
natural condition, the dentinal tubules are filled with a clear
fluid, which penetrates from the vascular structures in the
pulp-cavity.

Cement. — Covering the dentine of the root, is a thin layer
of true bony structure, called the cement, or crusta -petrosa.
This is thickest at the summit and the deeper portions of the
root, where it is sometimes lamellated, and becomes thinner
near the neck. It finally becomes continuous with the en-
amel of the crown, so that the dentine is everywhere com-
pletely covered. The cement contains true bone-lacunae and
canaliculi, and in very old teeth, a few Haversian canals,
except near the neck, where the layer is very thin. It is
closely adherent to the dentine and the periosteum lining
the alveolar cavities.

142 DIGESTION.

Pulp-Cavity. — In the interior of each tooth, extending
from the apex of the root or roots into the crown, is the pulp-
cavity, which contains a collection of minute blood-vessels and
nervous filaments, held together by longitudinal fibres of the
white fibrous tissue. This is the only portion of the tooth
endowed with sensibility. Its blood-vessels and nerves pene-
trate by a little orifice at the extremity of the root.

The dentine and enamel of the teeth must be regarded as
perfected structures ; for when the second or permanent teeth
are lost, they are never reproduced, and when these parts are
invaded by wrear or by decay, they are incapable of regen-
eration. The integrity of the pulp, even, is not necessary to
the stability of the teeth; for examples are numerous in
which the pulp loses its vitality from various causes, and yet
the tooth remains, is as serviceable as ever, being only dis-
colored by the decomposition of the structures in the pulp-
cavity, which can neither escape nor become absorbed.

The descriptive anatomy of the teeth in the human sub-
ject shows how well calculated they are to perform their
varied functions, and how admirably they are adapted to a
diet composed of articles derived from both the animal and
vegetable kingdom. The thirty-two permanent teeth are
divided as follows :

1. Eight incisors, four in each jaw, called the central and
lateral incisors.

2. Four canines, or cuspidati, two in each jaw, just back
of the incisors. The upper canines are sometimes called the
eye-teeth, and the lower canines, the stomach-teeth.

3. Eight bicuspid — the small, or false molars — just back
of the canines ; four in each jaw.

4. Twelve molars, or multicuspid, situated just back of
the biscuspid ; six in each jaw.

The incisors are wedge-shaped, flattened antero-posteri-
orly, and bevelled at the expense of the posterior face, giving
them a sharp cutting edge, which is sometimes perfectly
straight, but is generally more or less rounded. The upper

DESCRIPTIVE ANATOMY OF THE TEETH. 143

incisors are generally larger and stronger than the lower.
In the upper jaw the central incisors are larger than the lat-
eral ; while in the lower jaw the lateral incisors are larger than
the central. Each of the incisors has but a single root. The
special function of the incisor teeth is to divide the food as
it is taken into the mouth. The permanent incisors make
their appearance from the seventh to the eighth year.

The canines are more conical and pointed than the in-
cisors, and have longer and larger roots, especially those in
the upper jaw. Their roots are single. They are used to
some extent, in connection with the incisors, in dividing the
food ; but have no prominent function in tearing the food,
as in the carnivora, in which they are extraordinarily de-
veloped. ' The permanent canines make their appearance
from the eleventh to the twelfth year.

The bicuspid teeth are shorter and thicker than the
canines. Their opposed surfaces are rather broad and are
marked by two eminences. The upper bicuspids are some-
what larger than the lower. The roots are single, but in
the upper jaw are slightly bifurcated at their extremities.
They are used, with the true molars, in triturating the food.
The permanent bicuspids make their appearance from the
ninth to the tenth year.

The molar teeth, called respectively — counting from before
backward — the first, second, and third molars, are the largest
of all, and are, par excellence, the teeth used in mastication.
Their form is that of a cube, rounded laterally, and provided
with four or five eminences on their opposed surfaces. The
first molars are the largest. They have generally three roots
in the upper jaw, and two in the lower ; although they some-
times have four and even five roots. The second molars are
but little smaller than the first, and resemble them in nearly
every particular. The third molars, called frequently the
wisdom-teeth, are much smaller than the others, and are by
no means so useful in mastication. In the upper jaw the
root is grooved or imperfectly divided into three branches ;

1M DIGESTION.

but in the lower jaw it generally has two distinct branches.
The first molars are the first of the permanent teeth ; making
their appearance between the sixth and the seventh year.
The second molars appear from the twelfth to the thirteenth
year; and the third molars from the seventeenth to the
twenty-first year, and sometimes even much later. In
some instances the third molars are never developed.

The upper jaw has ordinarily a somewhat longer and
broader arch than the lower; so that when the mouth is
closed the teeth are not brought into exact apposition, but
the upper teeth overlap the lower teeth both in front and lat-
erally. The lower teeth are all somewhat smaller than the
corresponding teeth in the upper jaw, and generally make
their appearance a little earlier.

The physiological anatomy of the maxillary bones and of
the temporo-maxillary articulation necessarily precedes the
study of the muscles of mastication and the mechanism of
their action.1

The superior maxillary bones are immovably articulated
with the other bones of the head, and do not usually take
any active part in mastication ; but their inferior borders,
with the upper teeth embedded in the alveolar cavities,
present fixed surfaces against which the food is pressed by
the action of the muscles which move the lower jaw.

The inferior maxilla is a single bone. Its body is hor-
izontal, of a horse-shoe shape, and in the alveolar cavities in
its superior border are embedded the lower teeth. Below
the teeth, both externally and internally, are surfaces for the
attachments of the muscles concerned in the various move-
ments of the jaw, and one of the muscles of the tongue.

Behind this horizontal body, on either side, is a vertical

1 The mechanism of mastication in the human subject is more complex than
in any of the inferior animals ; and it is absolutely necessary to enter into tolera-
bly minute details of the anatomy of the parts concerned in this function, in or-
der to comprehend their physiology.

TEMPOBO-M A XILL ART ARTICULATION. 145

portion called the ramus. In the adult, this forms nearly a
right angle with the body, making what is called the angle
of the jaw. Superiorly, the ramus terminates in two pro-
cesses, separated by a deep groove called the sigmoid notch.
The posterior process is the condyle, or condyloid process ;
the anatomy of which will be considered further on in treat-
ing of the temporo-maxillary articulation. The anterior pro-
cess, called the coronoid process, is for the attachment of the
temporal muscle, one of the most powerful of the muscles of
mastication. The greater portion of the external surface of
the ramus, extending down to the angle, is for the attach-
ment of the masseter muscle. The internal surface of the
ramus gives attachment to several muscles, viz. : the external
pterygoid, attached to the neck just below the condyle ; the
temporal, the attachment to the coronoid process being much
more extensive on the internal than on the external surface ;
and the internal pterygoid, which has its attachment at the
angle.

Temporo -Maxillary Articulation. — The various classes
of mammalia present great differences in the temporo-maxil-
lary articulation — differences which indicate, to a great ex-
tent, their natural diet. In the carnivora, the long diameter
of the condyle is transverse, and it is so firmly embedded, in
the deep glenoid cavity of the temporal bone, as to admit of
extended movements in but one direction. In these animals,
lateral and antero-posterior sliding movements of the jaw are
impossible, and there is very little mastication of the food.
In the rodentia, the long diameter of the condyle is antero-
posterior, the peculiar gnawing movements in these animals
requiring a considerable sliding movement of the lower jaw
in this direction. In the herbivora, particularly the rumi-
nants, the condyle is small and slightly concave instead of
convex, as in most other animals. It moves on a large pro-
jecting surface on the temporal bone, and the entire jaw is
capable of remarkably extensive lateral movements.
10

146 DIGESTION.

In man, the articulation of the lower jaw with the tempo-
ral bone is such as to allow, to a considerable extent, of an
antero-posterior sliding movement and a lateral movement, in
addition to the ordinary movements of elevation and depres-
sion. The condyloid process is convex, with an ovoid surface,
the general direction of its long diameter being transverse and
slightly oblique from without inward and from before back-
ward. This process is received into a cavity of correspond-
ing shape in -the temporal bone, called the glenoid fossa,
which is bounded, anteriority, by a rounded eminence (erni-
nentia articularis), the uses of which will be more fully de-
scribed in connection with the movements of the jaw.

Between the condyle of the lower jaw and the glenoid
fossa, is an oblong, inter-articular disk of fibre-cartilage.
This disk is thicker at the edges than in the centre. It is
pliable, and so situated that when the lower jaw is projected
forward, making the lower teeth project beyond the upper, it
is applied to the convex surface of the eminentia articularis
and presents a concave surface for articulation with the con-
dyle. One of the uses of this cartilage is to constantly present
a proper articulating surface upon the articular eminence,
and thus admit of the antero-posterior sliding movement of
the lower jaw. It is also important in the lateral movements
of the jaw, in which one of the condyles remains in the gle-
noid cavity, and the other is projected, so that the bone un-
dergoes a slight rotation.

Muscles of Mastication. — To the lower jaw are attached
certain muscles by which it is depressed, and others by
which it is elevated, projected forward and drawn backward,
and moved from side to side. The following are the princi-
pal muscles concerned in the production of these varied
movements :

MUSCLES OF MASTICATION. 147

Muscles of Mastication.
Muscles which depress the lower jaw.
Muscle. Attachments.

Digastric. . . . , Mastoid process of the temporal bone —

Lower border of the inferior maxilla
near the symphysis ; with its central
tendon held to the side of the body
of the hyoid bone.

Mylo-hyoid Body of the hyoid bone— Mylo-hyoid

ridge on the internal surface of the
inferior maxilla.

Genio-hyoid Body of the hyoid bone — Inferior gen-
ial tubercle on the inner surface of the
inferior maxilla near the symphysis.

Platysma myoides Clavicle, acromion, and fascia — Anterior

half of the body of the inferior max-
illa near the inferior border.

Muscles which elevate the lower jaw, and move it laterally and antero-pos-

teriorly.

Temporal Temporal fossa — Coronoid process of

the inferior maxilla.

Masseter Malar process of the superior maxilla,

lower border and internal surface of
the zygomatic arch — Surface of the
ramus of the inferior maxilla.

Internal Pterygoid Pterygoid fossa — Inner side of the ra-
mus and angle of the inferior maxilla.

External Pterygoid. Pterygoid ridge of the sphenoid, the

surface between it and the pterygoid
process, external pterygoid plate, and
the tuberosity of the palate and the
superior maxillary bone — Inner sur-
face of the neck of the condyle of
the inferior maxilla and the inter-
articular fibro-cartilage.

Action of the Muscles which depress the Lower Jaw. — The
most important of these muscles have for their fixed point of
action the hyoid Lone, which, under these circumstances, is
fixed by the muscles which extend from it to the upper part
of the chest. The central tendon of the digastric, as it per-

148 DIGESTION.

forates the stylo-hyoid, is connected with the hyoid bone by
a loop of fibrous tissue ; and acting from this bone as the fixed
point, the anterior belly must of necessity tend to depress
the jaw. The attachments of the mylo-hyoid and the genio-
hyoid render their action in depressing the jaw sufficiently
evident, which is also the case with the platysma myoides,
acting from its attachments to the upper part of the thorax.

It has been a disputed question whether the upper jaw
does or does not participate in the act of opening the mouth.
That depression of the lower jaw is the main action in ordi-
nary mastication is sufficiently evident ; but it is possible,
by fixing the lower jaw, to perform the acts of mastication
— laboriously and imperfectly it is true — by movements
of the upper jaw. In ordinary mastication, the upper jaw
undergoes a slight movement of elevation in opening the
mouth ; and this becomes somewhat exaggerated when the
mouth is opened to the fullest possible extent. Without
citing the various authorities for and against this opinion, it
will be sufficient, perhaps, to mention the following simple
experiment, suggested to Monro by Pringle : " If," says he,
" you place the blade of a knife or the finger nail in a situa-
tion which corresponds precisely with the point of contact of
the teeth, when the mouth is closed, the knife being held in
a fixed position during the time when the mouth is opened,
it can be observed in a mirror that the upper teeth are sensi-
bly elevated every time the mouth is opened." 1

Many speculations have been put forward by those who
adopt this view, as to the precise muscular action involved
in this movement, which is necessarily a movement of the
entire head. It is possible that the posterior belly of the
digastric may have such an action, to a slight extent. The
movement of the head, however, does not ordinarily require
any powerful muscular action, and is probably the result of
the contraction of muscles too deeply situated to be ex-
plored experimentally. It is evidently not due, as a rule, to

1 Cited by BERARD, Cours de Physiologic, Paris, 1848, tome i., p. 617.

MUSCLES OF MASTICATION. 14-9

the contraction of those of the posterior muscles of the neck,
which have for their chief function the elevation of the head.

Action of the Muscles which elevate the Lower Jaw, and
move it laterally and antero-joosteriorly. — The temporal,
masseter, and internal pterygoid muscles are chiefly con-
cerned in the simple act of closing the jaws. As this is al-
most the only movement of mastication in many of the car-
nivora, in this class of animals these muscles are most largely
developed. Their anatomy alone gives a sufficiently cleai
idea of their mode of action ; and their immense power, even
in the human subject, is explained by the number of their
fibres, by the attachments of many of these fibres to the
strong aponeuroses by which they are covered, and the fact
that the distance from their origin to their insertion is very
short.

The attachments of the internal and external pterygoids
are such that by their alternate action, on either side, the
jaw may be moved laterally, as their points of origin are
situated in front and within the temporo-maxillary articu-
lation. As was first shown by Ferrein,1 the articulation of
the lower jaw is of such a nature that, in its lateral move-
ments, the condyles themselves cannot be sufficiently dis-
placed from side to side, but with the condyle on one side
fixed or moved slightly backward, the other may be brought
forward against the articular eminence, producing a move-
ment of rotation. The pterygoid muscles are largely de-
veloped in the herbivora, in which the lateral movements of
mastication are so important.

The above explanation of the lateral movements of the
jaw presupposes the possibility of movements in an antero-
posterior direction. Movements in a forward direction, so as
to make the lower teeth project beyond the upper, are
effected by the pterygoids, the oblique fibres of the masseter,

1 FERREIN, Memoire sur les mouvemenls de la MAdioire inferieure. — Memoires
de fAcad. des Sciences, Paris, 1744, p. 434.

150 DIGESTION.

with the anterior fibres of the temporal. By the combined
action of the posterior fibres of the temporal, the digastric,
mylo-hyoid, and genio-hyoid, the jaw is brought back to its
position. By the same action it may also be drawn back
slightly from its normal position while at rest.

Action of the Tongue, Lips, and Cheeks, in Mastication.
— Experiments on living animals and phenomena observed in
cases of lesions of the nervous system in the human subject
have fully demonstrated the importance of the tongue and
cheeks in mastication. The following observations of Pa-
nizza on the effects of section of both hypoglossal nerves in
dogs show the importance of the tongue, both in mastication
and deglutition : " After the section of the hypoglossal the
movements of the tongue cease immediately, but the gen-
eral sensibility of that organ and the taste was not less
marked. Indeed, if milk, or bread moistened in the
liquid, were presented to the dog, he made ineffectual efforts
to lap and to masticate, moving the head and the lower jaw;
the tongue, when displaced, remaining in the same position,
and even when a bolus of meat or bread was put on its an-
terior surface, it was found for a long time after in the same
place, which proves that section of the hypoglossals destroys
not only the movements necessary to mastication, but also
those of deglutition." * "We have lately had occasion to ver-
ify most of these observations by Panizza in a dog in which
both sublingual nerves were divided. The experiment, how-
ever, was made chiefly with reference to the action of the
tongue in deglutition.

Section of the facial nerves is now a common physiolo-
gical experiment ; and operations of this kind, with cases of
facial palsy, which are not uncommon in the human subject,
show that when the cheek is paralyzed the food accumulates
between it and the teeth, producing great inconvenience.

1 PANIZZA, Nouvelles Recherches Experimentales sur les Nerfs. — Gazette Mcdi-
cale de Paris, 1835, p. 419.

MUSCLES OF MASTICATION. 151

In animals, like the herbivora, that use the lips and tongue
extensively in the prehension of food, division of the facial
and hypoglossal nerves interferes materially with this func-
tion.

The tongue is a muscular organ which, by virtue of the
complex arrangement of its fibres, is capable of a great va-
riety of important movements. Reference has already
been made to the importance of- these movements in suc-
tion. By the action of what are called the extrinsic mus-
cles of the tongue, the organ is moved in various directions,
while the intrinsic muscles are capable at the same time
of producing many changes in its form. For example, by
the action of those fibres of the genio-hyo-glossal muscles
which are attached to the chin and the posterior part of the
tongue, the whole organ is carried forward and may be pro-
truded* to a considerable extent. At the same time the
whole length of the muscles may act upon the middle line of
the tongue, to which they are attached, and depress the cen-
tre so as to render it concave from side to side ; or the trans-
verse fibres of the tongue may act so as to make it longer
and narrower. The tongue is drawn into the mouth by the
action of the anterior fibres of the genio-hyo-glossus on either
side, and may be still further shortened by the contraction
of the stylo-glossus, and the interior fibres of the hyo-glossus
— its intrinsic and superior longitudinal fibres. The general
action of the stylo-glossus, on either side, is to draw down
the sides of the tongue and make it convex from side to side.
The stylo-glossus and the palato-glossus draw the back of
the tongue upward and backward toward the pharynx, and
are thus useful in the first processes of deglutition. By the
combined and varied actions of these and other muscles, the
tongue is made to perform the numerous movements which
take place in connection with phonation, suction, mastica-
tion, deglutition, etc.

The varied and complicated movements of the tongue
during mastication are not easily described. After solid

152 DIGESTION.

food is taken into the mouth, the tongue prevents its escape
from between the teeth ; and, by its constant movements,
rolls the alimentary bolus over and over, and passes it at
times from one side to the other, so that it may undergo
thorough trituration. Aside from functions of the tongue as
an organ of taste, its surface is endowed with peculiar sensi-
bility as regards the consistence, size, and form of different
articles ; 1 and this property is undoubtedly important in de-
termining when mastication is completed; although the
thoroughness with which mastication is accomplished is very
much influenced by habit.

Tonic contraction of the orbicularis oris is necessary to
keep the fluids in the mouth during repose ; and this muscle
is sometimes brought into action when the mouth is very
full, to assist in keeping the food between the teeth. This
latter function, however, is mainly performed by the buc-
cinator j the action of which is to press the food between the
teeth and keep it in place during mastication ; assisting, from
time to time, in turning the alimentary bolus so as to subject
new portions to trituration.

The process of mastication is regulated to a very great
extent by the exquisite sensibility of the teeth to the impres-
sions of hard and soft substances. It is only necessary to call
attention to the ease and certainty with which we recognize the
presence and the consistence, even of the smallest substance
between the teeth, in order to appreciate the advantages of
this tactile sense in mastication. It is in this way, mainly,
that we are notified when the process of mastication is com-
pleted ; and it is this sense which admonishes us instantly of
the presence of bodies too hard for mastication, which, if al-
lowed to remain in the mouth, might seriously injure the
teeth. Attention was called to these interesting facts by the
late Dr. Graves, of Dublin, who says : " In truth, the teeth

1 Every one is aware how readily a hair, or any minute substance, which
would hardly be felt even by the ends of the fingers, is detected in the mouth ;
and how annoying the sensation is until the offending substance is removed.

MUSCLES OF MASTICATION. 153

may, in this point of view, be considered as a sort of fingers
fixed within the mouth, destined to feel, examine, and adjust
the morsel preparatory to placing it in the position most fa-
vorable to its mastication." * He further states that though
this subject has engaged his attention for several years, he
has observed no cases of paralysis in which this peculiar sen-
sibility was affected.

In persons who use false teeth, the pressure on the gums
in mastication takes the place imperfectly of the tactile sen-
sibility of the natural teeth. The sensibility of the latter is
dependent, undoubtedly, on the nerves distributed to the
dental pulp.

Summary of the Process of Mastication. — The various
muscles attached to the lower jaw are competent to bring
the teeth together, and to produce a lateral movement and a
movement backward and forward. Some articles of food are
torn asunder by movements of the head and the upper ex-
tremities, as in the carnivora, or divided by the incisors, as
in the herbivora. After the food is taken into the mouth, it
is kept between the molars and subjected to their triturating
action, which is. effected by movements of opening and clos-
ing the jaws, conjoined with marked lateral movements.
The position of the muscles and the peculiar construction of
the temporo-maxillary articulation are sucli as to enable the
condyles of the inferior maxilla, on either side, to alternately
slide forward, producing rotation and deviation of the bone
to the opposite side. In this movement, the condyle, cov-
ered by the pliable inter-articular fibro-cartilaginous disk, and
thus presenting a concave articulating surface, is brought in
contact with the articulating eminence in front of the gle-
noid cavity of the temporal bone.

Mastication should be continued until the alimentary bolus
has become thoroughly triturated. . The food, at the same time,

1 GRATES, On a Peculiar Affection of the Nerves of the Teeth. — Dublin Jour-
nal of Medical Science, 1836, vol. ix., p. 3.

.

154 DIGESTION.

!

becomes incorporated with the fluids of the mouth, particu-
larly that poured out by the parotid glands, and entangles a
considerable quantity of air. This preparation is important
in insuring the prompt and efficient action of the gastric juice.
It is less essential in the digestion of animal than of vegeta-
ble food, but still increases the facility of digestion of both.
Many of the vegetable grains which are covered with a hard
epidermis, when they escape the action of the teeth, are apt
to pass through the alimentary canal unchanged, and may be
recognized entire in the fseces. This fact with regard to the
digestion of vegetable grains was proven, early in the history
of the physiology of digestion, by the experiments of Spal-
lanzani, who forced fowls and rooks to swallow small, per-
forated metallic tubes filled with beans and grains of wheat.
When the grains were enclosed in these tubes entire, he
found them but slightly swollen and softened after a number
of hours' sojourn in the stomach ; but when the grains were
introduced slightly broken, they were found, in one experi-
ment, to lose one-fourth of their weight in eight hours, and
were at last entirely dissolved.1 This fact was further con-
firmed by experiments on sheep, in which a number of tubes,
some filled with herbs entire, and others with herbs which
had been triturated, were introduced into the alimentary canal.
At the end of thirty-three hours, five tubes were discharged
by the anus. In two of these, in which the food had been
introduced entire, the contents were apparently unchanged,
but in the others, in which the food had been triturated,
nothing remained but a small amount of indigestible matter.3

1 SPALLANZANI, Opuscules de Physique, Animate et Vegetale, Pavie, 1787, tome
ii., p. 462.

2 Ibid., p. 552.

CHAPTEE YI.

INSALIVATION.

General considerations — Parotid saliva — Relations of the parotid secretion to
mastication — Submaxillary saliva — Relations of the submaxillary secretion
to mastication and gustation — Sublingual saliva — Fluids from the smaller
glands of the mouth, tongue, and fauces — Mixed saliva — Quantity of saliva —
General properties and composition of the saliva — Functions of the saliva — Ac-
tion of the saliva on starch — Mechanical functions of the saliva.

ONE of the most important of the digestive processes
which take place in the mouth is the incorporation of the
saliva with the food, or insalivation. Not only has this fluid
a mechanical function, assisting to reduce the food to the
proper form and consistence to be easily swallowed, but it
seems to be necessary to the proper performance of the sub-
sequent processes of digestion, and is concerned to a consid-
erable extent in the transformation of starch into sugar. That
the saliva is necessary to digestion is proven by the grave
effects upon the general function of nutrition which follow
its loss in any considerable quantity. This occasionally oc-
curs from the habit of excessive spitting, or as the result of
salivary fistula. It becomes important, therefore, to study
the physical and chemical properties of the saliva, the sources
from which it is derived, and its mechanical and chemical
functions in digestion.

Saliva.

The fluid which is mixed with the food in mastication,
which moistens the mucous membrane of the mouth, and

156 DIGESTION.

which may be collected at any time in small quantity by the
simple act of sputation, is composed of the secretions of a
considerable number and variety of glands. The most im-
portant of these are the parotid, submaxillary, and sublin-
gual, which are usually called the salivary glands, and, in
addition, the labial and buccal glands, the follicular glands of
the tongue and general mucous surface, and certain glandular
structures in the mucous membrane of the pharynx. The
liquid which becomes more or less incorporated with the food
before it descends to the stomach, and which must be con-
sidered as the digestive fluid of the mouth, is known as the
mixed saliva ; but the study of the composition and proper-
ties of this fluid as a whole should be prefaced by a consid-
eration of the different fluids of which it is composed.

The salivary glands belong to the variety of glands called
racemose. They closely resemble the other glands belonging
to this class, and their structure will be considered more par-
ticularly under the head of secretion.

Parotid Saliva. — The parotid is the largest of the three
salivary glands. It is situated below and in front of the ear,
and opens, by the duct of Steno, into the mouth at about the
middle of the cheek. The papilla which marks the orifice
of the duct is situated opposite the second large molar tooth
of the upper jaw. Bernard, to whom belongs the credit of
having established the general physiological distinctions be-
tween the different fluids which enter into the composition
of the mixed saliva, cites Hapel de la Chenaie as the first to
obtain the pure parotid saliva from the horse, by section of
the duct of Steno, in 1780.1 Tiedemann and Gmelin, in their
work on digestion, recognized the distinction between the
saliva found in the mouth, and the secretion of the parotid,

1 BERNARD, Lemons de Physiologie Experimentale, Paris, 1856, p. 30. The
original memoir by Hapel de la Chenaie ( Observations et Experiences sur V analyse
de la Salive du ChevaT), is published in the Memoires de la Societe Royale de Me-
decine, Paris, 1780 and 1781, p. 325.

INS ALI VATION. 157

taken from the duct of Steno.1 Numerous opportunities have
presented themselves, in cases of salivary fistula, for the study
of the properties of the pure parotid saliva in the human
subject; and the situation of the duct of Steno, in the her-
bivora especially, is such that this fluid can easily be obtained
by operations on the inferior animals. Prof. Dalton has
obtained the pure parotid saliva from the human subject by
simply introducing a silver tube, of from ^j to -jV of an inch
in diameter, into the duct by its opening into the mouth.2 In
this way the fluid may be obtained with great facility and in
absolute purity ; and by this means, Prof. Dalton has devel-
oped many interesting facts connected with its function, be-
side confirming some of the important observations of Ber-
nard, Colin, and others, on the inferior animals. The quan-
tity thus obtained was considerable. In one observation,
four hundred and eighty grains flowed from a tube intro-
duced into the duct of Steno in the course of twenty min-
utes ; and in seven successive observations, made on different
days, comprising in all three hours and nine minutes, a little
over three thousand grains were collected.3

1 TIEDEMANX ET GMELiN, Redierches Experimentales Physiologiques et Chi-
miques sur la Digestion, traduit par JOURDAN, Paris, 1827, tome i., p. 4 et seq.

2 DALTOX, A Treatise on Human Physiology, third edition, Philadelphia,
1864, p. 125 et seq.

3 The saliva thus obtained was analyzed under the direction of Prof. Dalton
by Mr. Maurice Perkins, Assistant to the Professor of Chemistry in the College
of Physicians and Surgeons, New York (op. cit., p. 126). A point to be re-
marked in this analysis is the large proportion of organic matter, which is sev-
eral times greater than that given by others for the parotid, or even for the mixed
saliva :

Composition of Human Parotid Saliva.

Water 983-308

Organic matter precipitable by alcohol 7 '352

Substances destructible by heat, but not precipitated by alcohol or acids 4-810

Sulpho-cyanide of sodium 0-330

Phosphate of lime 0-240

Chloride of potassium 0-900

Chloride of sodium and carbonate of soda 3-060

1,000-000

158 DIGESTION.

The following facts with regard to the properties of the
parotid saliva observed "by Dalton are given in his own
words, in a communication kindly made in answer to certain
inquiries :

" On the 28th of July, 1863, I obtained, from a strong,
healthy man, about two drachms of the mixed saliva of the
mouth, by causing him to hold in his mouth for a short time
a clear glass stopper, and collecting the secretion as it was
discharged.

" One hour afterward 1 obtained, from the same man, four
drachms of pure parotid saliva, by introducing a long silver
canula into the natural orifice of Steno's duct, on the left
side, and collecting the saliva as it flowed from the outer ex-
tremity of the canula.

" The two kinds of saliva compared as follows :

" Both were distinctly alkaline in reaction ; the parotid
saliva rather the more so.

" The parotid saliva was rather clear and watery in ap-
pearance ; .the saliva of the mouth was quite opaline, with
admixture of buccal epithelium, but became clear on filtra-
tion.

" The parotid saliva was rendered turbid by the action of
heat, and by the addition of nitric acid, as well as sulphate
of soda in excess ; but not by sulphate of magnesia, nor by
ferro-cyanide of potassium with acetic acid.

" The saliva of the mouth, filtered clear, became turbid by
heat and by nitric acid ; but showed no precipitate by either
sulphate of soda or sulphate of magnesia in excess. There
was also a slight precipitate on the addition of pure acetic
acid, which did not take place in the parotid saliva.

" The parotid saliva showed no traces of sulpho-cyanogen
on the addition of the perchloride of iron ; but they were
distinctly marked in the buccal saliva.

" On mixing the two kinds of saliva with boiled starch,
and keeping the mixture at the temperature of 100° Fahr.,
sugar was present in loth specimens at the end of five min-

INSALIVATED^. 159

utes. Tliere was no marked difference between them in this
respect.

u While making some similar experiments to the above
on a previous patient, in April, 1863, I found that with the
canula introduced into Steno's duct, not only was the dis-
charge of parotid saliva increased by the mastication of food,
but that it ran from the canula very much faster than in a
state of rest, whenever the patient smiled, spoke, or moved
his lips or cheeks in any way."

The organic matter of the parotid saliva is coagulable by
heat (212° Fahr.), alcohol, and the strong mineral acids.
Dalton found, in the human saliva, that it wras also coagulated
by an excess of sulphate of soda ; but Bernard states that in
the parotid saliva of the horse, the organic matter will pass
through a mixture of sulphate of soda, but is coagulated by
sulphate of magnesia.1 Almost all physiologists agree that
this organic matter is not identical in its properties with
albumen, nor with the peculiar principle described by
Mialhe in the mixed saliva, under the name of animal dias-
tase.2

A compound of sulpho-cyanogen is now generally ac-
knowledged to be a constant constituent of the parotid saliva.
This cannot be recognized by the ordinary tests in the fresh
saliva taken from the duct of Steno, but in the clear filtered
fluid which passes after the precipitation of the organic mat-
ter, there is always a distinct red color on the addition of
the persulphate of iron. As this reaction is more marked in
the mixed saliva, the methods by which the presence of a
sulpho-cyanide ^is to be demonstrated will be considered in
connection with that fluid.

In the human subject, the parotid secretion is more abun-
dant than that of any other of the salivary glands. The en-
tire quantity in the twenty-four hours has not been directly

1 BERNARD, Lemons de Physiologic Experimental^, Paris, 1856, p. 67.
a MIALHE, Chimie appliquee d la Physiologic d d la Therapeutique, Paris, 1856,
p. 39.

160 DIGESTION.

estimated ; but Prof. Dalton found that during mastication,
the quantity secreted in twenty minutes on one side was
127*5 grains, and on the other side, 374 '4 grains.

A curious fact with regard to the influence of mastica-
tion upon the flow from the parotids was observed by Colin
in the horse, ass, and ox. He found that when mastication
was performed on one side of the mouth, the flow from the
gland on that side was greatly increased, exceeding by sev-
eral times the quantity produced on the opposite side.1 This
fact was confirmed by Dalton, as already indicated, in the
human subject.2

The flow of saliva from the parotid takes place with
greatly increased activity during the process of mastication.
The orifice of the parotid duct is so situated that the fluid
is poured directly upon the mass of food as it is undergoing
trituration by the teeth ; and as the secretion is more abun-
dant on the side on which mastication is going on, and as
the consistence of the fluid is such as to enable it to mix
readily with the food, the function of this gland is supposed
to be particularly connected with mastication. This is un-
doubtedly the fact ; though its flow is not absolutely confined
to the period of mastication, but continues, in small quantity,
in the intervals. Its quantity is regulated somewhat by the
character of the food, being much greater when the articles
taken into the mouth are dry than when they contain consid-
erable moisture. Colin has shown in some of the herbivora
a remarkable insensibility of the parotids to the stimulus of
sapid and aromatic substances applied to the mucous mem-
brane of the cheeks. In the ruminants, in which there is a
constant flow from these glands, the quantity cannot be in-
creased by the action of salts, feeble acids, or aromatic sub-
stances.3 The experiments of Bernard on dogs show a cer-

1 COLIN, Traite de PJiysiologie Comparee des Animaux Domestiques, Paris,
1854, tome i., p. 468.
3 Loc. cit.
8 Op. cit., p. 471.

INSALIVATION. 161

tain increase in the flow of saliva from a tube introduced
into the duct of Steno, on the application of vinegar to the
mucous membrane of the mouth ; but this was slight as com-
pared with the increase in the flow of the submaxillary secre-
tion.1 There is, in fact, a great difference in different animals
as regards the excitability of the salivary glands by substances
introduced into the mouth. In the human subject, the exci-
tation produced by sapid substances will sometimes induce a
great increase in the flow of the parotid saliva. Mitscherlich
and Ebeiie2 observed this in persons suffering from salivary
fistula, and noted, furthermore, that the mere sight or odor
of food produced the same effect. Magendie mentions a case
in which the sight of food produced such an effect that the
saliva was discharged from the duct to the distance of several
feet.8

The supposition, which has been entertained by some
authors, that the flow from the parotid is dependent upon
the mechanical pressure of the muscles or of the condyle of
the lower jaw during mastication has no foundation in fact.
It is now well established that one of the indispensable con-
ditions in the production of a secretion is a great increase
in the quantity of blood circulating in the gland, and that
the vascular supply is regulated through the nervous system.
It is not rational to suppose that the parotid is an exception
to this rule ; and Bernard has shown that galvanization of the
small root of the fifth pair of nerves and of the facial immedi-
ately produces an intense parotid secretion.4 The fact that
an alternation in the parotid secretion accompanies an alter-
nation in the act of mastication is also an argument against
this mechanical theory; for it is not to be supposed that

1 BERNARD, Lecons sur les Proprietes, etc., des Liquides de V Organisme, Paris,
1859, tome ii., p. 250 et seq.

2 MITSCHERLICH, Ueber den Speichel des Menschcn. — Poggendorff's Annalen der
PhysiTc und Chemie, 1833, Bd. xxvii., S. 328.

3 MAGENDIE, Freds JEUmentaire de Physiologie, Paris, 1836, tome ii., p. 56.

4 BERNARD, Lemons de Physiologie Experimentale, Paris, 1856, p. 69.

11

162 DIGESTION.

during mastication there exists a difference in the pressure
of the muscles or of the condyles on the two sides, corre-
sponding with the di-fferences which have been noted in the
secretion from the glands on either side. In the horse and
in the dog, it has been observed that the secretion of the paro-
tids is completely arrested during the deglutition of liquids,
while the flow from the other salivary glands is not affected.1

To sum up the functions of the parotid saliva, — aside
from any chemical action which it may have upon the food,
which will be fully considered in connection with the mixed
saliva, — it evidently has an important mechanical office. It
is discharged in large quantity during the entire process of
mastication, and is poured into the mouth in such a manner
as to become of necessity thoroughly incorporated with the
food. Its function is chiefly, though not exclusively, connect-
ed with mastication, and indirectly with deglutition ; for it
is only by becoming incorporated with this saliva, that the
deglutition of dry pulverulent substances is rendered possible.
Facts in comparative physiology, showing a great development
of the parotids in animals that masticate very thoroughly,
particularly the ruminants, a slight development in those
that masticate but slightly, and the absence of these glands in
animals that do not masticate at all,2 are additional arguments
in favor of these views.

Su~bmaxillary Saliva. — In the human subject, the sub-
maxillary is the second of the salivary glands in point of size.
Its minute structure is the same as that of the parotid. As
its name implies, it is situated below the inferior maxillary
bone, and is found in the anterior part of what is known as
the submaxillary triangle of the neck. Its excretory duct,
called sometimes the duct of Wharton, is about two inches

1 BERNARD, op. dt., p. 52.

3 MILNE-EDWARDS, Legons sur la Physiologic et V Anatomic Comparee, Paris,
1859, tome vi., p. 239.

INSALIVATION. 163

in length, and passes from the gland, beneath the tongue, to
open by a small papilla by the side of the frenum. This
gland is relatively very small in the herbivora, but is largely
developed in the carnivora ; in the latter being larger than
the parotid.

The pure submaxillary saliva presents many important
points of difference from the secretion of the parotid. It
was first studied as a distinct fluid by Bernard. It may be
obtained by exposing the duct and introducing a fine silver
tube, when on the introduction of any sapid substance into
the mouth, the secretion will flow in large pearly drops. Ber-
nard found this variety of saliva much more viscid than the
secretion from the parotid. It is perfectly clear, and, on
cooling, frequently becomes of a gelatinous consistence.1 Its
organic matter is not coagulated by heat. In the dog it is
rather more strongly alkaline than the parotid saliva. Ac-
cording to Bernard, it does not contain the sulpho-cyanide
of potassium.2

1 BERNARD, Lemons de Physiologie Experimental, Paris, 1856, p. 72. The
late experiments of Bernard concerning the influence of the nervous system on
secretion were made chiefly on the submaxillary gland. These points will be fully
considered under the head of Secretion.

2 BIDDER AND SCHMIDT give the following as the result of two analyses of the
submaxillary saliva:

ffirst Analysis.

Water 996-04

Organic matter 1-51

Inorganic matter 2-45

1,000-00
Second Analysis.

Water 991-45

Organic matter 2-89

f Chloride of calcium i

Chloride of sodium j 4'50

Inorganic matter -I Carbonate of lime \

Phosphate of lime (• 1-16

[ Phosphate of magnesia )

1,000-00
— Die Verdauungssaftt, Leipzig, 1852, S. 8.

164 DIGESTION.

The submaxillary gland pours out its secretion in great-
est abundance when sapid substances are introduced into
the mouth. Bernard io of the opinion that the function of
this gland is connected exclusively with gustation, and that
secretion never takes place except in obedience to stimula-
tion of the gustatory nerves.1 It is undoubtedly true that the
most marked influence of sapid substances is upon the sub-
maxillary gland, and that this is the case in dogs has been
sufficiently proven by experiments. In the solipeds and
ruminants, Colin has observed that the quantity of submax-
illary saliva secreted is much increased during eating ; but,
unlike the parotids, the secretion does not alternate on the
two sides with the alternation in mastication. He has
found in all the domestic animals, that the flow is greatly
influenced by the degree of sapidity of the food.2 As regards
the special functions of the different salivary glands, it is im-
possible to reason directly from the inferior animals to the
human subject ; and the distinction which Bernard has en-
deavored to establish between the different glands is undoubt-
edly too rigorous. Although sapid articles induce an abun-
dant secretion from the submaxillary glands, they also pro-
duce an increase in the secretions from the parotids and sub-
linguals ; and, 011 the other hand, movements of mastication
increase somewhat the flow from the submaxillaries, and
these glands secrete a certain amount of fluid during the
intervals of digestion. The viscid consistence of the sub-
maxillary saliva renders it less capable of penetrating the
alimentary mass during mastication than the parotid secre-
tion, so that it remains chiefly on or near the surface of the
bolus.

S'ublingual Saliva. — The sublinguals, the smallest of
the salivary glands, are situated beneath the tongue, on ei-

1 Op. tit., p. 85.

>J COLIN, Traite de Physiologie Comparee des Animaux Domestiques, Paris,
1854, tome i., p. 473.

INSALIVATTON. 165

ther side of the frenum. In minute structure they resemble
the parotid and the submaxillary glands. Each gland has a
number of excretory ducts, from eight to twenty, which
open into the mouth by the side of the frenum ; one of the
ducts, larger than the others, joins the duct of the submax-
illary gland near its termination in the mouth.

The secretion of the sublingual glands is more viscid
even than the submaxillary saliva ; but it differs in the fact
that it does not gelatinize on cooling. It is so glutinous that it
adheres strongly to any vessel, and flows with difficulty from
a tube introduced into the duct. Like the secretion from the
other salivary glands, its reaction is distinctly alkaline. Its
organic matter is not coagulated by heat, acids, nor the
metallic salts. According to Bernard, after desiccation it is
redissolved by water, and its viscid properties are then re-
stored.1

In accordance with the view entertained by Bernard
concerning the function of this variety of saliva and its spe-
cial connection with deglutition, it is supposed to be secreted
immediately before and during the act of swallowing. The
experiments which are advanced in support of this view are
mostly those in which a tube was fixed in each of the three
salivary ducts in a dog ; when the animal was caused to make
movements of the jaw, movements of deglutition, and at the
same time the gustatory nerves were stimulated by the intro-
duction of vinegar into the mouth. In an experiment of
this kind, it was observed that fluid was secreted by all the
glands, but in unequal proportions ; " the submaxillary sali-
va flowed very abundantly, the parotid saliva much less, and
the sublingual saliva flowed very feebly."2 Although the

1 BERNARD, op. cit., p. 92.

Bernard gives a table of the composition of the sublingual saliva taken from
Bidder and Schmidt. This is an error. The table referred .to is the composi-
tion of the mucous secretion of the mouth (Mundschleiiri) ; and the authors re-
ferred to only analyzed, as distinct secretions, the parotid and sublingual saliva,
the compositions of which have been given. (Die Verdauungssafte, etc., S. 5.)

2 BERNARD, op. cit., p. 81.

166 DIGESTION.

animal made movements of mastication, experienced a gusta-
tory impression, and made movements of deglutition, it is by
no means evident from this observation, nor from others re-
ported by Bernard, that the flow of ttye sublingual saliva had
any special connection with the. act of deglu^tion. The ob-
servations of Colin on this subject show that^n the domestic
ruminants, there is a constant flow of the sublingual saliva
during the time occupied in eating.1

It has been experimentally demonstrated that the sub-
lingual glands may be excited to secretion by impressions
made by sapid substances upon the nerves of taste, though
the flow is always less than from the submaxillary glands.
The great viscidity of the sublingual saliva renders it less
easily mixed with the alimentary bolus than the secretions
from the parotid or submaxillary glands.

Fluids from the Smaller Glands of the Mouth, Tongue,
and Pharynx. — Beneath the mucous 'membrane of the inner
surface of the. lips, are small, rounded glandular bodies, open-
ing by numerous ducts into the buccal cavity, called the la-
bial glands ; and in the submucous tissue of the cheeks, are
similar bodies, called the buccal glands. The latter are some-
what smaller than the labial glands. Two or three of the
buccal glands are of considerable size, and have ducts open-
ing opposite the last molar tooth ; and these are sometimes
distinguished as the molar glands. There are also a few small
glands in the mucous membrane of the posterior half of the
hard palate ; but the glands on the under surface of the soft
palate are larger and more numerous, and here form a con-
tinuous layer. The glands of the tongue (lingual glands) are
situated beneath the mucous membrane, mainly on the poste-
rior third of the dorsum ; but a few are found at the edges
and the tip. All of these are small racemose glands, similar
in structure to those which have been called the true salivary

1 COLIN, Traile de Physiologic Comparee des Animaux Domesliques, Paris,
1854, tome i., p. 483.

INSALIVATION. 167

glands. In addition to these structures, the mucous mem-
brane of the tongue is provided with a number of simple and
compound follicular glands, which extend over its entire
surface, but are most abundant at the posterior portion, be-
hind the circumvallate^papillse.

In the pharynx and the posterior portico, of the buccal
cavity, are found the pharyngeal glands and the tonsils.
In the pharynx, particularly the upper portion, racemose
glands, like those found in the mouth, exist in large num-
bers. The mucous membrane is provided, also, with numer-
ous simple and compound mucous follicles. The tonsils, situ-
ated on either side of the fauces between the pillars of the
soft palate, consist of an aggregation of compound follicular
glands, held together by fibrous tissue. The number of
glands entering into the composition of each tonsil is from
ten to twenty.1

The secretion from the glands and follicles above enu-
merated cannot be obtained, in the human subject, unmixed
with the fluids from the true salivary glands. It has been
obtained, however, in small quantity, from the inferior ani-
mals, after ligation of all the salivary ducts. This secretion
is simply a grayish, viscid mucus, containing a number of
leucocytes and desquamated epithelial scales. It is this
which gives the turbid and opaline character to the mixed
saliva, as the secretions of the various salivary glands are
all perfectly transparent. The fluid from these glands in
the mouth is mixed with the salivary secretions ; and that
from the posterior part of the tongue, the tonsils, and the
pharyngeal glands passes down to the stomach with the ali-
mentary bolus. This secretion consequently forms a constant
and essential part of the mixed saliva."

Mixed Saliva. — Although the study of the distinct secre-
tions discharged into the mouth possesses considerable physi-

1 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 284.

168 DIGESTION.

ological interest and importance, it is only the fluid resulting
from a union of them all, which can properly be considered
in connection with the general process of insalivation. In
man it is necessary that the cavity of the mouth should be
continually moistened, if for nothing else, to keep the parts
in a proper condition for phonation. A little reflection will
make it apparent that the flow, from some of the glands at
least, is constant, and that from time to time a certain quan-
tity of saliva is swallowed. This is even more marked in
some of the inferior animals, as the ruminants. The dis-
charge ol fluid into the mouth, though diminished, is not
arrested during sleep. In the review of the different kinds
of saliva, it has been seen that the flow from none of the
glands is absolutely intermittent ; unless, occasionally, from
the parotid, the secreting function of which is most power-
fully influenced by the act of mastication and the impres-
sion of sapid substances.

Upon the introduction of food, the quantity of saliva is
enormously increased ; and we have already noted the influ-
ence of the sight, odor, and occasionally even the thought of
agreeable articles. Many persons present a marked increase in
the flow of saliva at the sight of a lemon ; and we are all famil-
iar, in a general way, with the impressions which bring " wa-
ter into the mouth." 1 The experiments of Frerichs on dogs
with gastric fistulse,2 and the observations of Gardner on a
patient with a wound in the oesophagus,3 have demonstrated
that the flow of saliva may be excited by the stimulus of
food introduced directly into the stomach without passing

1 COLIN (op. cit.y p. 471) has failed to excite the salivary secretion in the
horse by the sight of food ; but the fact with regard to the human subject has
been repeatedly noted by physiologists.

8 FRERICHS, Die Verdauung. — WAGNER'S Handworterbuch der Physiologie,
Braunschweig, 1846, Bd. ill, S. 759.

8 GARDNER, Case of a Wound of the Throat in which the Trachea and (Esoph-
agus were divided across, and which did not terminate fatally, although the parts
have not reunited. — Edinburgh Medical and Surgical Journal, 1820, vol. xvi.,
p. 358.

QUANTITY OF SALIVA.

through the mouth. It is well known that the quantity of
saliva may be increased by directing the attention to this
secretion, moving the tongue about in the mouth, sucking
the cheeks, and discharging the fluid by sputation ; and it
may be largely increased by taking into the mouth glass
beads, pebbles, or smooth articles of this kind.

Quantity of Saliva. — It is not easy to estimate, in the
human subject, the entire quantity of saliva secreted in the
twenty-four hours ; and great variations in this regard un-
doubtedly exist in different persons, and even in the same
individual at different times. An approximate estimate may
be arrived at by noting, as nearly as possible, the average
quantity secreted during the intervals of digestion, and add-
ing to it the quantity absorbed by the various articles of food.
Some of the earlier physiologists investigated this subject
with much patience. Berard quotes the experiments of Sie-
bold, who collected the saliva by holding the mouth open
with the head inclined so that the fluid should flow into a
vessel as fast as secreted.1 An estimate of this kind can only
be approximative ; and those made by Dalton are apparently
the most satisfactory. This observer found that he was able
to collect from the mouth, without any artificial stimulus,
about five hundred and fifty-six grains of saliva per hour ;
and he also found that wheaten bread gained in mastication
fifty-five per cent., and lean meat forty-eight per cent, in
weight. Assuming the daily allowance of bread to be nine-
teen ounces, and the allowance of meat to be sixteen ounces,
and estimating the quantity of saliva secreted during twenty-
two hours of interval, the entire quantity in twenty-four hours
would amount to 20,164 grains, or a little less than three
pounds avoirdupois, of which rather more than one-half is
secreted during the intervals of eating.2

Remembering that the quantity of saliva must necessarily

1 Op. cit., tome i., p. 696.

2 DALTON, A Treatise on Human Physiology, Philadelphia, 1864, p. 128.

170 DIGESTION.

be subject to great variations, this estimate may be taken as
giving a sufficiently close approximation of the quantity of
saliva ordinarily secreted. It must be borne in mind, how-
ever, with reference to this and the other digestive secretions,
that this immense quantity of fluid is at no one time removed
from the blood, but is reabsorbed nearly as fast as secreted, and
that normally, none of it is discharged from the organism.

General Properties and Composition of Saliva. — The
mixed fluid taken from the mouth is colorless, somewhat
opaline, frothy, and slightly viscid. It generally has a faint
and somewhat disagreeable odor very soon after it is dis-
charged. If it be allowed to stand, it deposits a . whitish
sediment composed mainly of desquamated epithelial scales,
with a few leucocytes ; leaving the supernatant fluid tolera-
bly clear. Its specific gravity is variable ; ranging from
1,004 to 1,006 or 1,008. Its reaction is almost constantly
alkaline ; though, under certain abnormal conditions of the
system, it has occasionally been observed to be neutral, and
sometimes, though rarely, acid. We have occasionally ob-
served a distinctly acid taste in the saliva after very se-
vere, prolonged, and exhaustive muscular exertion. The sa-
liva becomes slightly opalescent by boiling and on the addi-
tion of the strong acids. The addition of absolute alcohol
produces an abundant, whitish, flocculent precipitate. Al-
most invariably the mixed saliva presents a more or less in-
tense blood-red tint on the addition of a per-salt of iron,
which is due to the presence of a sulpho-cyanide, either of
potassium or sodium.

A number of analyses of the human mixed saliva have
been made by different chemists, presenting, however, few
differences, except in the relative proportions of water and
solid ingredients, which are probably quite variable. One
of the most recent of these analyses is the following by Bid-
der and Schmidt : 1

1 BIDDER UND SCHMIDT, Die Verdauungssafte, Leipsig, 1852, S. 11.

COMPOSITION OF HUMAN SALIVA. 171

Composition of Human Saliva.

Water 995-16

Epithelium 1-62

Soluble organic matter 1-34

Sulpho-cyanide of potassium 0-06

Phosphates of soda, lime, and magnesia 0-98

Chloride of potassium i 0>g4
Chloride of sodium \ ' '

1,000-00

The organic principle of the mixed saliva, called by Ber-
zelius ptyaline, is not affected by heat or the acids, but
on the addition of an excess of absolute alcohol, is coagu-
lated in the form of whitish flakes, which may be readily
separated by filtration. This substance has been closely
studied by Mialhe, and is described by him under the name
of animal diastase. This author regards it as the active
principle of the saliva. It is obtained from the human saliva
by the following simple process :

The fluid from the mouth is first filtered, then treated
with five or six times its weight of absolute alcohol, by
which a white or grayish- white precipitate is formed. This
substance is collected on a filter, and is dried in thin layers
on a plate of glass in a current of air at from 100° to 120°
Fahr. It may then be preserved indefinitely in a well-
stoppered bottle.1 The principle thus prepared may be dis-
solved in water, when it is insipid, neutral, and becomes read-
ily decomposed, giving rise to a substance resembling butyric
acid. It has no influence upon the nitrogenized alimentary
principles, but when brought in contact with raw or hydrated
starch, readily transforms it, first into dextrine, and afterward
into glucose. According .to Mialhe, the energy of this action
is such that one part is sufficient to effect the transformation
of more than two thousand parts of starch.

The presence of a certain quantity of sulpho-cyanide of

1 MIALHE, Chimie appliguee d la Physiologic et d la Therapeutiquc, Paris, 1856,
p. 43.

DIGESTION.

potassium in the mixed saliva can be demonstrated by the
addition of a per-salt, especially the perchloride, of iron.
That this is a constant and normal ingredient of the human
saliva cannot be doubted. We have frequently had occasion
to apply this test to the saliva of different persons, and the
results have been invariably the same. The peculiar reaction
of the saliva with the perchloride of iron was first noticed by
Treviranus, who called the substance producing it blood-acid.
At the time this observation was made (1814), sulpho-cy-
anic acid had not been described. Tiedemann and Gmelin
confirmed this observation, and demonstrated the presence
of a sulpho-cyanide by other tests.1

It has been a question whether the red color produced by
the perchloride of iron be really due to the presence of a
sulpho-cyanide in the saliva ; or, if it exist at all, whether
this salt be a normal constituent, or be developed accident-
ally as a pathological condition, or produced, as has been
suggested, by the action of reagents. The elaborate investi-
gations of Longet seem to have settled these questions con-
clusively. He obtained nearly three quarts of human saliva,
which he collected in half an hour from forty soldiers, fast-
ing, who, after having rinsed and cleaned the mouth, excited
the secretion by chewing pieces of India rubber. The fluid
was then concentrated so that all the sulpho-cyanide was
brought into a few drops, which showed, to an intense de-
gree, the peculiar reaction with the perchloride of iron, By
suitable manipulations, the presence of sulphur was also es-
tablished.2

1 TIEDEMANN ET GMELIN, Recherches Experimentales, Physiologiques ct Chi-
miques sur la Digestion, Paris, 1827, premiere partie, p. 9 et seq.

2 LONGET, Traite. de Physiologic, Paris, 1861, tome i., p. 160. In these ma-
nipulations, Longet followed the process of Tiedemann and Gmelin (he. cit.),
whose observations on this point were simply confirmed; the difference being that
in the observations of Longet the extract was made from a very large quantity
of saliva. It is unnecessary to review the process by which it is demonstrated
that the reaction with the perchloride is not due to the presence of the acetate
of soda, as has been suggested.

COMPOSITION OF HUMAN SALIVA. 173

Longet states, furthermore, that he has examined the sa-
liva from a great number of persons, under all conditions,
and has never failed to demonstrate the presence of the sul-
pho-cyanide. Its proportion he found very variable, and in
some cases it was so slight that the reaction with the per-
chloride of iron did not immediately manifest itself; but by
slowly evaporating the liquid to one-half or one-third of its
original volume, the reaction became manifest in all cases.1

In examining the saliva of a number of persons, Bernard
found some in which no red color was produced by the addi-
tion of the perchloride of iron, and he remarked that all in
which the reaction was manifested were in the habit of
smoking. This led him to add a little nicotine to the speci-
mens of saliva which did not present this reaction, when a
red color, somewhat less intense than in the other specimens,
was produced.2 If, in these experiments, the saliva had been
slightly evaporated, it is probable that the reaction would
have been manifested. We have frequently demonstrated
to a medical class the presence of a sulpho-cyanide in the
saliva of persons who had never used tobacco.

It is probable that the sulpho-cyanide of potassium is a
constant ingredient of each of the three varieties of saliva.
It has been found in the parotid, in cases of salivary fistula,
and was noted by Dalton in the saliva taken from the duct
of Steno, though in this case the saliva contained an organic
principle which interfered with the test, but which could
be precipitated by alcohol and separated by filtration.3
I^onget found the sulpho-cyanide in the saliva from the sub-

1 Longet found the perchloride of iron a much more delicate test than the
persulphate, which is sometimes used. When the peculiar reaction shows itself
after evaporating the liquid, it is not due to mere concentration, but to some
change which occurs during the process ; for the color may be obtained when the
quantity of water .lost by evaporation has been restored. (BERNARD, Lemons de
Physiologic Experimentale, Paris, 1856, tome ii., p. 140.)

2 BERNARD, Liquides de VOrganisme, Paris, 1859, tome ii., p. 244.

3 See p. 157 (note). The analysis of Mr. Perkins gives the sulpho-cyanide of
sodium instead of the sulpho-cyanide of potassium.

174 DIGESTION.

maxillary and sublingual glands, taken from the floor of the
mouth behind the inferior incisor and canine teeth.1

Very little need be said concerning the remaining inor-
ganic constituents of saliva, except that they are of such a
nature as almost invariably to render the fluid distinctly al-
kaline. They exist in small proportion, and do not appear
to be connected in any way with the functions of the saliva
' as a digestive fluid.

Functions of the Saliva.

Physiologists are not entirely agreed concerning some
of the most important questions relating to the function
of the mixed saliva in digestion. Bernard, from observa-
tions on the lower animals, particularly on dogs, concludes
that the operation of the saliva is only mechanical ; while
others, in view of its property of rapidly transforming starch
into sugar, attribute to it an important chemical function.
The experiments on which the view of Bernard is based are
conclusive, so far as they go. He has shown that none of
the distinct varieties of saliva from the dog affect starch;
that a mixture of the fluids from the three salivary glands
is likewise inoperative ; and that the mixed saliva from the
mouth of the dog, containing the secretion of the mucous
glands of the mouth, converts starch into sugar with diffi-
culty. On the same page, however, he mentions the well-
known fact that the human mixed saliva changes starch into
sugar with great rapidity,2 and that the same effect is pro-
duced by the unmixed parotid or submaxillary secretion.3
In the dog, amylaceous principles taken by the mouth are
always found unaltered in the stomach, and are only trans-
formed into sugar in the small intestines ; but observations
have shown that this is not the case in the human subject.
These facts are a sufficient argument against the direct appli-

1LoNGET, op. cit., p. 162.

2 BERNARD, Lemons de Physiologic Experimentale, Paris, 1856, p. 157 et seq.

3 Ibid., p. 165.

FUNCTIONS OF THE SALIVA. 175

cation of experiments made on an exclusively carnivorous ani-
mal, like the dog, to the digestive process in man. While there
is no reason to suppose that there is any material difference
in the mammalia, as regards the general operation of some
of the functions, such as circulation or respiration, it is evi-
dent that differences exist in the properties of the digestive
fluids, as well as in the teeth and jaws, corresponding with
the great differences in the character and conditions of the
alimentary principles. In the study of digestion, therefore,
the results of experiments on the inferior animals cannot
always be taken without reserve, and must be confirmed by
observations on the human subject; but fortunately, the
properties of nearly all of the digestive fluids which have
been studied minutely by vivisections have been investigated
more or less fully in man.

In 1831, Leuchs discovered that hydrated starch, mixed
with fresh saliva and warmed, became liquid in the space of
several hours and was converted into sugar.1 This fact has
since been repeatedly confirmed ; and it is now a matter of
common observation that hydrated starch, or unleavened
bread, taken into the mouth, almost instantly loses the prop-
erty of striking a blue color with iodine, and responds to the
usual tests for sugar. Of the rapidity of this action any one
can easily convince himself by the simple experiment of tak-
ing a little cooked starch into the mouth, mixing it well with
the saliva, and testing in the ordinary way for sugar. This
can hardly be done so rapidly that the reaction is not mani-
fested ; and the presence of sugar is also indicated by the taste.
Though the human mixed saliva will finally exert the same
action on uncooked starch, the transformation takes place
much more slowly. It has been shown by experiment that all
the varieties of human saliva have the same effect on starch
as the mixed fluids of the mouth. Dalton found no difference
in the pure parotid saliva and the mixed saliva of the human
subject as regards the power of transforming starch into su-

1 BURDACH, Traite de Physiologic, Paris, 1841, tome ix., p. 265.

176 DIGESTION.

gar.1 Bernard obtained the pure secretions from the parotid
and from the subm axillary glands in the human subject, by
drawing it out of the ducts as they open into the mOuth,
with a small syringe with the nozzle arranged so as to
fit over the papillae, and demonstrated their action 011
starch.2 This fact, with regard to the parotid, had previ-
ously been established in a patient with a fistula into the
duct of Steno by Jarjavay and Mialhe, the experiment hav-
ing been made at the suggestion of M. Berard.3 In this case
the fluid from the fistula transformed starch into sugar with
great facility. Longet afterward showed that a mixture of
the secretions of the subrnaxillary and the sublingual glands
had the same property.4

It is unnecessary, in this connection, to recite the numer-
ous experiments on the influence of the saliva of the inferior
animals 011 starch ; but it may be stated, as an established
and generally accepted fact, that the mixed saliva and the
secretion of the different salivary glands, in the human sub-
ject, invariably transform cooked starch into sugar with
great rapidity in the mouth, and also, at the proper tempera-
ture, out of the body. It has been also shown by Mialhe
that the starch, though it is converted rapidly into sugar in
this process, is first transformed into dextrine.5

This point being settled, there arises the important ques-
tion whether the action of the saliva be really important in
the digestion of starch, or whether this transformation be
merely accidental ; for it has been shown that other fluids,

1 See page 159.

2 Loc. tit.

3 BERARD, Cours de Physiologic, Paris, 1849, tome ii., p. 403, note.

In many cases of salivary fistula, the fluid discharged failed to effect the
transformation of starch. In the observations of Prof. Dalton on the parotid
saliva taken from the duct by a tube introduced by the mouth, the transforma-
tion was complete. (Verbal communication.)

4 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 171.

8 MIALHE, Chimie appliquee d la Physiologie et d la Therapculique, Paris,
1856, p. 40,

» FUNCTIONS OF THE SALIVA. 177

among which may be mentioned the serum of the blood, the
fluid found in cysts, and mucus, have the same property ;
although none, except the intestinal juices, are nearly so effi-
cient as the saliva. And again, the quantity of starch contained
in the food is so great that it would require, apparently, a
longer contact with the saliva than usually takes place in the
mouth to make this action very effective. These considera-
tions make it necessary to follow the amylaceous principles
of food into the stomach, and ascertain, if possible, whether
the transformation into sugar be continued in this organ.

Bernard, after feeding a dog with starch, drew off the
contents of the stomach by a gastric fistula, and found the
starch unchanged, with no traces of sugar.1 This experi-
ment we have often repeated in public demonstrations, with
the same results ; but the differences already noted in the
properties of the saliva of the human subject and of the in-
ferior animals destroy much of the value of this observation.
Longet2 and others have showrn that the addition of gastric
juice to the saliva does not interfere with the action of the
latter on starch, but it has been found that the reaction of
the sugar thus resulting from the transformation of the starch
is masked by the presence of other principles contained in the
stomach. The question of the continuance, in the stomach,
of the digestion of starch by the saliva is settled by the fol-
lowing observation by Griinewaldt and Schroeder, in 1853,
on a woman with a gastric fistula : 3

" After a meal of raw starch, no sugar was found in the
contents of the stomach, the acid juice was drawn by the
fistula, and was mixed with paste ; the transformation into
sugar commenced immediately. As Bidder has observed,
the transforming property of the saliva persists, even in the
presence of free acids.

" A few ounces of starch swelled with boiling water were

: Op. cit., p. 159.

2 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 173.
8 Cited by LONGET, op. cit., p. 174.
12

178 DIGESTION.

introduced in the stomach, fasting, by the fistula ; immedi-
ately after, a portion of the starch was expelled again;
already it contained sugar. A quarter of an hour after, a
great deal of sugar was found in the stomach, and the paste
had become entirely fluid."

There can be no doubt that the saliva, in addition to its
important mechanical functions, transforms a considerable
portion of the cooked starch, which is the common form in
which this principle is taken by the human subject, into
sugar; but it is by no means the only fluid engaged in
its digestion, similar properties belonging, as we shall see
hereafter, to the pancreatic and the intestinal juice. The
last-named fluids are probably more active, even, than the
saliva. The saliva acts slowly and imperfectly on raw
starch, which is hydrated in the stomach and digested main-
ly by the fluids of the small intestine. In all probability,
the saliva does not digest all the hydrated starch taken as
food ; the greater part passing unchanged from the stomach
into the intestine. Those who attribute only a mechanical
function to the saliva draw their conclusions entirely from
experiments on the lower animals, particularly the carniv-
ora ; and it is evident that such observations cannot be strictly
applied to the human subject.1

The principle which is specially active in the digestion of

1 In the herbivora, the chemical action of the saliva is much more important
than in the carnivora. In the report of a commission of the Academy of Sci-
ences, in 1845, composed of Magendie, Rayer, Payen, and others, the following
interesting facts were developed concerning the mixed saliva of the horse :

" This saliva was obtained in a state of purity by causing a horse, that had
an opening into the O3sophagus, to eat bran washed, first with cold water, and
afterward with boiling distilled water. * * * *

" The bran thus prepared was given to the horse, who chewed it, moistened
it with saliva, and swallowed it ; and it is the liquid pressed from the masses
and filtered which has been studied under the name of the mixed saliva. * *

" Like the human saliva taken from the mouth, the mixed saliva of the horse
transforms starch-paste instantly into sugar at 104° Fahr. At the temperature
of 104,° it has a slow but sensible action on raw starch and on coagulated albu-
men."—Compos Rendus, Paris, 1845, pp. 903, 904.

FUNCTIONS OF THE SALIVA. 179

starch, in the human subject at least, must exist in the pure
secretion from the various glands, as well as in the mixed
saliva. It has been isolated and studied by Mialhe, under
the name of animal disastase. Its properties and its action
on starch have already been noted in treating of the compo-
sition of the mixed saliva.

In treating of the various fluids which are combined to
form the mixed saliva, their mechanical functions have neces-
sarily been touched upon. To sum up this subject, however, it
may be stated that the fluids of the mouth and pharynx have
quite as important an office in preparing the food for deglu-
tition and for the action of the juices in the stomach, as in the
digestion of starch. Indeed, the former is probably the more
important function in man and the herbivora. It is a. matter
of common experience that the rapid deglutition of very dry
articles is impossible; and the experiments of Bernard and
others on horses furnish very striking illustrations of the im-
portance of the saliva as a purely mechanical agent. In
the human subject, though mastication and insalivation
are by no means so complete as in some of the lower ani-
mals, the quantity of saliva absorbed by the various articles
of food is enormous. The observations of Dalton, which
have been already referred to in treating of the entire quan-
tity of saliva, show that white bread absorbs in the mouth
fifty -five per cent., and cooked meat, forty-eight per cent, of
its original weight.1 It seems impossible that the fluid
thus incorporated with the alimentary principles should not
have an important influence on the changes which take place
in the stomach, though it must be confessed that our infor-
mation on this point is very meagre, except as regards the
digestion of starch.

It is undoubtedly the abundant secretion of the parotid
glands which becomes most completely incorporated with
the food during mastication, and serves to unite the dry par-
ticles into a single coherent mass. In an experiment on a
1 Op. tit., p. 128.

180 DIGESTION.

horse, Bernard found that after the ducts of Steno had been
divided, the portions of food, which were collected by an
opening into the oesophagus as they were swallowed, were
not coherent and were passed into the stomach with great
difficulty. The time occupied in eating about three-quarters
of a pound of oats was twenty-five minutes ; while before
the section of the salivary ducts, a pound of oats was eaten
in nine minutes.1

The secretions from the submaxillary and sublingual
glands and the small glands and follicles of the mouth, being
more viscid and less in quantity than the parotid secretion,
penetrate the alimentary bolus less easily, and have rather
a tendency to form a glairy coating on its exterior ; ag-
glutinating the particles on the surface with peculiar tena-
city.

When the process of mastication and insalivation is com-
pleted, and the food is passed back into the pharynx, it meets
with the secretion of the pharyngeal glands, which still fur-
ther coats the surface with the viscid fluid which covers the
mucous membrane in this situation, thus facilitating the first
processes of deglutition.

It has been observed that the saliva has a remarkable
tendency to entangle bubbles of air in the alimentary mass.
In mastication, a considerable quantity of air is mixed with
the food, and this undoubtedly facilitates the penetration of
the gastric juice. It is well known that moist, heavy bread,
and articles that cannot become impregnated in this way
with air, are not easily acted upon in the stomach.

1 BERNARD, Legons de Physiologic Experimental, Paris, 1856, p. 146.

CHAPTER YII.

DEGLUTITION.

Physiological anatomy of the parts concerned in deglutition — Pharynx — Muscles
of the pharynx — Muscles of the soft palate — Mucous membrane of the phar-
ynx— (Esophagus — Mechanism of deglutition — First period of deglutition —
Second period of deglutition — Protection of the posterior nares during the
second period of deglutition — Protection of the opening of the larynx — Func-
tion of the epiglottis — Study of deglutition by auto-laryngoscopy — Third period
of deglutition — Intermittent contraction of the lower third of the oesophagus
— Nature of the movements of deglutition — Deglutition of air.

Deglutition.

DEGLUTITION is the act by which solid and liquid articles
-ire forced from the mouth into the stomach. The process
involves first, the passage — lay a voluntary movement — of the
alimentary mass through the isthmus of the fauces into the
pharynx ; then a rapid contraction of the constrictors of the
pharynx, by which it is forced into the oesophagus; and,
finally, a peristaltic action of the muscular walls of the
oesophagus extending from its opening at the pharynx to the
stomach.

Physiological Anatomy of the Parts concerned in Deg-
lutition. — The parts concerned in this function are the
tongue, the muscular walls of the pharynx, and the oeso-
phagus. In the passage of food and drink through the
pharynx, it is necessary to completely protect from the en-
trance of foreign matters a number of openings which are
exclusively for the passage of air. These are the posterior

182 DIGESTION.

nares and the Eustachian tubes, above ; and below, the open-
ing of the larynx. The mechanism by which these passages
are closed during the acts of deglutition is one of the most
interesting subjects connected with this function, and Jias
long engaged the attention of physiologists.

The tongue — a muscular organ capable of a great variety
of movements, and endowed, as we have seen, with highly
important functions connected with mastication — is the chief
agent in the first processes of deglutition. Its physiological
anatomy has already been considered.

The pharynx, in which the, most vigorous and complex
of the movements of deglutition take place, is an irregularly
funnel-shaped cavity, its longest diameter being transverse and
opposite the cornua of the hyoid bone, with its smallest por-
tion at the opening into the oesophagus. Its length is about
four and a half inches. It is connected superiorly and pos-
teriorly with the basilar process of the occipital bone and
the upper cervical vertebrse. It is imperfectly separated
from -the cavity of the mouth by the velum pendulum palati,
a movable musculo-membranous fold, continuous with the
roof of the mouth and marked by a line in the centre, which
indicates its original development in two lateral halves.
This, which is called the soft palate, when relaxed, presents
a concave surface looking toward the mouth, a free, arched
border, and a conical process hanging from the centre, called
the uvula. On either side of the soft palate are two curved
pillars or arches.

The anterior pillars of the fauces are formed by the pala-
to-glossus muscle on either side, and run obliquely downward
and forward ; the mucous membrane which covers them be-
coming continuous with the membrane of the base of the
tongue. The posterior pillars are more closely approxi-
mated to each other than the anterior. They run obliquely
downward and backward, their mucous membrane becoming
continuous with the membrane covering the sides of the
pharynx. Between the lower portion of the anterior and

DEGLUTITION.

183

posterior pillars, are the tonsils ; and in the substance of, and
beneath the mucous membrane of the palate and pharynx,
are small glands, which have already been described.

In Fig. 1 are shown the cavities of the mouth and phar-
ynx, with their relations to the nares and the larynx.

FIG. 1.

Section in the median line of the face and the superior portion of the neck, de-
signed to show the mouth in its relations to the nasal fossce, the pharynx, and
the larynx. (SAPPEY, Traite d' Anatomic Descriptive, Paris, 1857, tome iii., p.
44.)

1. Sphenoidal sinuses. — 2. Internal orifice of the Eustachian tube. — 3. Pala-
tine arch. — 4. Velum pendulum palati.— 5. Anterior pillar of the soft palate.
— 6. Posterior pillar of the soft palate. — 7. Tonsil. — 8. Lingual portion of the
cavity of the pharynx. — 9. Epiglottis. — 10. Section of the hyoid bone. — 11. La-
ryngeal portion of the cavity of the pharynx. — 12. Cavity of the larynx.

184 DIGESTION.

The isthmus of the fauces, or the strait through which the
food passes from the mouth to the pharynx, is thus bounded
above by the soft palate and the uvula ; laterally, by the pil-
lars of the palate and the tonsils ; and below, by the base of
the tongue.

The openings into the pharynx above are the posterior
nares and orifices of the Eustachian tubes. Below, are the
openings of the oesophagus and the larynx.

The muscles of the pharynx are the superior constrictor,
the stylo-pharyngeus, the middle constrictor, and the inferior
constrictor ; and it is easy to see, from the situation of these
muscles, how, by their successive action from above down-
ward, the food is passed into the oesophagus.

The superior constrictors form the muscular wall of the
upper part of the pharynx. Their origin extends from the
lower third of the margin of the internal pterygoid plate of
the sphenoid bone to the alveolar process of the last molar
tooth, the intermediate line of attachment being to tendons
and ligaments. The fibres then pass backward and meet in
the median raphe, which is attached by apeneurotic fibres
to a ridge on the basilar process of the occipital bone, called
the pharyngeal spine.

The stylo-pharyngeus muscle has a rounded portion
above by which it arises from the inner surface of the base of
the styloid process of the temporal bone. It passes between
the superior and middle constrictors of the pharynx, becomes
thin, and spreading out, its fibres mingle in part with the
fibres of the constrictors and the palato-pharyngeus, and a few
pass to be inserted into the upper border of the thyroid carti-
lage.

The middle constrictor is a flattened muscle arising from
the cornua of the hyoid bone and the stylo-hyoid ligament ;
its fibres passing backward, spreading into a fan shape, and
meeting in the median raphe.

The inferior constrictor is the most powerful of the mus-
cles of the pharynx. It arises by thick fleshy masses from

DEGLUTITION. 185

the sides of the thyroid and cricoid cartilages of the larynx.
The inferior fibres curve backward, and the superior fibres
backward and upward, to meet in the median raphe.

The muscles which form the fleshy portions of the soft
palate are likewise important in deglutition.

The levator palati, a long muscle of considerable thick-
ness, arises from the apex of the petrous portion of the
temporal bone and the adjacent cartilaginous portion of the
Eustachian tube ; and spreading out in the posterior portion
of the soft palate, as its name implies, it raises the velum.

The tensor palati, sometimes called the circumflexus, is a
broad thin muscle consisting of a vertical portion which is
fleshy, and a horizontal portion which is tendinous. Tho
fleshy fibres arise from the scaphoid fossa of the sphenoid
bone, pass downward, become tendinous, and wind around
the hamular process ; after which the muscle spreads out
into a thin apeneurosis which passes to the median line on
the anterior portion of the soft palate. Its action is to make
the palate tense.

The palato-glossus forms the anterior pillar of the soft
palate. It arises from the side of the palate near the uvula
and passes to be inserted into the side and dorsum of the
tongue. The action of this muscle is to constrict the isthmus
of the fauces by drawing down the soft palate and elevating
the base of the tongue.

The palato-pharyngeus forms the posterior pillar of the
soft palate. It arises from the soft palate by two fasciculi,
and joins with the fibres of the stylo-pharyngeus, to be in-
serted into the posterior border of the thyroid cartilage. Its
action is to approximate the posterior pillars of the palate
and depress the velum.

The azygos uvulse is the small muscle, consisting of two
fasciculi, one on either side, which forms the fleshy portion
of the uvula. It has no very marked or important action in
deglutition.

The mucous membrane of the pharynx, — aside from the

186 DIGESTION.

various glands situated beneath it and in its substance, which
have already been described, — presents some peculiarities,
which are interesting more from an anatomical than a physi-
ological point of view. In the superior portion, which forms a
cuboidal cavity just behind the posterior nares, the membrane
is darker and much richer in blood-vessels than in other
parts. Its surface is smooth and provided with ciliated col-
umnar epithelium, like that which covers the membrane of
the posterior nares. It is marked by a deep antero-posterior
groove in the median line ; and on either side, parallel with
the median line, are four smaller grooves. In the horizontal
portions, the mucous membrane in the central groove adheres
to the periosteum of the basilar process, particularly at its
posterior extremity. Laterally, below the level of the open-
ing of the Eustachian tubes, and posteriorly, at the point where
it becomes vertical, the mucous membrane abruptly changes
its character. The epithelial covering is here composed of
cells of the pavement variety, similar to those which cover
the mucous membrane of the oesophagus. The membrane is
also paler, and is less rich in blood-vessels. It is provided
with papillae, some of which are simple conical elevations, while
others are split into from two to six conical processes with a
single base. These papillae are rather thinly distributed over
the whole of that portion of the mucous surface which is cov-
ered with pavement epithelium.

The contractions of the muscular walls of the pharynx
force the alimentary bolus into the oesophagus, a tube pos-
sessed of thick muscular walls, extending to the stomach.
The oesophagus is about nine inches in length. It is cylin-
drical, and rather constricted at its superior and inferior ex-
tremities. It commences in the median line behind the
lower border of the cricoid cartilage and opposite the fifth
cervical vertebra. At first, as it descends, it passes a little
to the left of the cervical vertebrae. It then passes from left
to right from the fourth or fifth to the ninth dorsal vertebra,
to give place to the aorta. It finally passes a little to the

DEGLUTITION. 1ST

left again, and from behind forward, to its opening into the
stomach. In its passage through the diaphragm, it is sur-
rounded by muscular fibres, so that when this muscle is con-
tracted in inspiration, its action has a tendency to close the
opening.

The coats of the oesophagus are two in number, unless
we include, as a third coat, the fibrous tissue which attaches
the mucous membrane to the subjacent muscular tissue.

The external coat is composed of an external longitudi-
nal, and an internal circular or transverse layer of muscular
fibres. In the superior portion, the longitudinal fibres are
arranged in three distinct fasciculi : one in front, which passes
downward from the posterior surface of the cricoid cartilage ;
and one on either side, extending from the inferior constric-
tors of the pharynx. As the fibres descend, the fasciculi
become less distinct, and are finally blended into a uniform
layer. The circular layer is somewhat thinner than the ex-
ternal layer. Its fibres are transverse near the superior and
inferior extremities of the tube, and are somewhat oblique in
the intermediate portion. The muscular coat is fiom ^to
y1^ of an inch in thickness.

In the upper third of the tube, the muscular fibres are ex-
clusively of the red or striated variety, with some anastomos-
ing bundles ; but lower down, there is a mixture of non-stri-
ated fibres, which appear first in the circular layer. These
latter fibres become gradually more numerous, until, in the
lower fourth, they largely predominate. A few striated
fibres, however, are found as low down as the diaphragm.1

1 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1864, p. 314.

Sappey (Traite cT Anatomic Descriptive, Paris, 1857, tome iii., p. 92) makes
the extraordinary statement that " the fleshy layer of the oesophagus is formed
exclusively of smooth fibres." He says that it is very easy to distinguish the
striae of the red fibres with a magnifying power of two-hundred diameters ; and
that these are never observed in fibres taken from any part of the oesophagus. It
is remarkable that, at the present day, there should be any difference of opinion
concerning a question so easily decided as that of the constitution of the muscu-
lar coat of the oesophagus. Immediately before writing this paragraph, we had

188 DIGESTION".

The mucous membrane of the oesophagus is attached to
the muscular tissue by a dense fibrous layer. It is quite vas-
cular and reddish above, but becomes gradually paler in
the inferior portion. The mucous membrane is ordinarily
thrown into longitudinal folds, which are obliterated when the
tube is distended. Its epithelium is thick, of the pavement
variety, and is continuous with, and similar to the cover-
ing of the lower portion of the pharynx. It is provided with
papillse of the same structure as those found in the pharynx,
the conical variety predominating. Numerous small race-
mose glands are found throughout the tube, forming by their
aggregation at the lower extremity, just before it opens into
the stomach, a glandular ring.

Mechanism of Deglutition. — For convenience of descrip-
tion, physiologists have generally divided the process of deg-
lutition into three periods. The first period is occupied by
the passage of the alimentary bolus backward to the isthmus
of the fauces. This may appropriately be considered as a dis-
tinct period, because the movements are effected by the action
of muscles entirely under the control of the will. The second
period is occupied by the passage of the food from the isthmus
of the fauces, through the palate, into the upper part of the
oesophagus. The third period is occupied by the passage of
the food through the oesophagus into the stomach.

In the first period, the tongue is the important agent.

ocular proof of the inaccuracy of the assertion made by Sappey. In the human
oesophagus, there is a manifest difference in color between the upper and lower por-
tions. Above, the color is red ; and below, it becomes paler and more like the in-
voluntary muscular tissue. A specimen taken from any of the deep-red portions
shows the striae of the red muscular fibres with a £ inch objective as distinctly as
could be desired. Passing down the tube, small bands of this red tissue are
seen, which likewise present, on microscopic examination, the striated muscular
fibre. These we demonstrated down as far as the diaphragm ; though in the
lower portions, the unstriped fibres were found to predominate. The examina-
tions were made with a binocular microscope, which singularly increases the
beauty and distinctness of the appearances.

DEGLUTITION. 189

After mastication has been completed, the mouth is closed
and the tongue, collecting with the point aided by the cheeks
all the particles of food into a single mass, becomes slightly
increased in width, and with the alimentary bolus behind
it, is pressed from before backward against the roof of the
mouth. The act of swallowing is always performed with
difficulty when the mouth is not completely closed ; for the
tongue, from its attachments, must follow, to a certain extent,
the movements of the lower jaw. The first part of the first
period of deglutition is thus simple ; but when the food has
passed beyond the hard palate, it comes in contact with the
hanging velum, and the muscles are brought into action
which render this membrane tense, and oppose it in a cer-
tain degree to the backward movement of the base of the
tongue. This is effected by the action of the tensor-palati
and the palato-glossus. The moderate tension of the soft
palate admits of its being applied to the smaller morsels,
while the opening is dilated somewhat forcibly by masses of
greater size.

It is easy to appreciate, in analyzing the first period of
deglutition, that liquids and the softer articles of food are as-
sisted in their passage to the isthmus of the fauces by a slight
suction force. • This is effected by the action of the muscles of
the tongue, elevating the sides and depressing the centre of the
dorsum, while the soft palate is accurately applied to the base.

The importance of the movements of the tongue during
the first period of deglutition is evidenced by experiments on
the inferior animals, and by cases of loss of this organ in the
human subject. In the experiments of Panizza, which have
already been referred to in connection with mastication, it
was found that paralysis- of the tongue, by section of the
hypoglossal nerves in dogs, deprived the animals of the power
of swallowing, even when a bolus of meat or bread was put
upon its anterior surface.1 "We have now a young dog under

1 PANIZZA, Nouvelles Recherches Experimentales sur Ics Nerfs. — Gazette Midi-
cole de Paris, 1835, p. 419.

190 DIGESTION.

observation, in which both hypoglossal nerves have been
divided, and the effect upon deglutition is very marked. The
animal eats with difficulty, the pieces of meat which are
given him frequently dropping from the mouth. He is only
able to swallow by jerking the head suddenly upward, so as
to throw the meat past the base of the tongue ; and even when
deglutition commences, the first steps take place slowly and
with apparent difficulty. The process of drinking is very
curious. The animal makes the usual noise in attempting
to drink, but the tongue does not come out of the mouth,
and the only way he seems to get any water is by jerking
the head and moving the jaw so as to throw some of the
liquid into the mouth. "When he attempts to drink from a
basin, the water is spattered in every direction. He ap-
pears to get more from a tall, narrow vessel. On causing
him to drink from a graduated glass, it was found that he
drank four fluid ounces in four minutes. In the case of
a young girl, reported to the Academy of Science, in 1718,
by De Jussieu, in which there was congenital absence
of the tongue, deglutition was impossible until the food had
been pushed with the finger far back into the mouth.1 In
cases of amputation of the tongue, a sufficient portion of its
base generally remains to press against the palate and effect
deglutition.

The movements in the first period of deglutition are un-
der the control of the will, but are generally involuntary.
When the food has been sufficiently masticated, it requires
an effort to prevent the act of swallowing. In this respect
the movements are like the acts of respiration ; except that
the imperative necessity of air in the system must, in a short
time, overcome any voluntary effort by which respiration is
arrested.

1 DE JUSSIEU, Observation sur la manure dont une Fille sans Langue s1 acquit
dcsfondions qui dependent decctorgane. — Memoircs de I1 Academic Royale des Sci-
ences, Paris, 1718, p. 8.

DEGLUTITION. 191

The second period of deglutition involves more complex
and important muscular action than the first. By a rapid
and almost convulsive series of movements, the food is made
to pass through the pharynx into the oesophagus. The
movements are now entirely beyond the control of the will,
and belong to the kind usually called reflex. After the ali-
mentary mass has passed beyond the isthmus of the fauces,
it is easy to observe a sudden and peculiar movement of
elevation of the larynx by the action of muscles which
usually depress the lower jaw, but which are now acting
from this bone as the fixed point. The muscles which produce
this movement act chiefly upon the hyoid bone. They are
the digastric (particularly the anterior belly), the mylo-hyoid,
the genio-hyoid, the stylo-hyoid, and some of the fibres of
the genio-glossus. It is probable, also, that the thyro-hyoid
acts at this time to draw the larynx toward the hyoid bone.
With this elevation of the larynx, there is necessarily an ele-
vation of the anterior and inferior portions of the pharynx,
which are, as it were, slipped under the alimentary bolus as
it is held by the constrictors of the isthmus of the fauces.

Contraction of the constrictor muscles of the pharynx
takes place almost simultaneously with the movement of
elevation ; and the superior constrictor is so situated as to
grasp the morsel of food, and with it the soft palate. The
mechanism of this act was first fully described by Gerdy.1

According to this description, the pharynx closely and
suddenly embraces the velum with the base of the tongue,
entirely obliterates the lower part of its cavity, and forces the
alimentary bolus to pass out. It is easy to understand,
then, how readily the food, made into a yielding mass by
mastication and insalivation, and coated with slimy mucus,
can be made to pass through the isthmus of the fauces over
the membrane, which is covered also with a glairy secretion.
The middle and inferior constrictors — the largest and most

1 GERDY, Note sur les mouvements de la langue et quelques mouvements du Pha-
rynx.— Bulletin des Sciences Medicales, Paris, 1830, tome xx., p. 33.

192 DIGESTION.

powerful of the muscles of the pharynx — and the stylo-
pharyngeus contract in connection with the superior con-
strictors. These muscles, the constrictors acting from the
median raphe, assist to elevate the anterior and inferior walls
of the pharynx and pass the food rapidly into the upper part
of the oesophagus. All these complex movements are accom-
plished with great rapidity, and the larynx and pharynx are
then immediately returned to their original position.

Protection of the Posterior Nares during the Second
Period of Deglutition. — When the act of deglutition is per-
formed with regularity, no portion of the liquids and solids
swallowed ever find their way into the air-passages. The
entrance of foreign substances into the posterior nares is pre-
vented in part by the action of the superior constrictors of
the pharynx, which, as we have seen, embrace, during their
contraction, not only the alimentary mass, but the velum
pendulum palati itself ; and in part, also, by contraction of
the muscles which form the posterior pillars of the soft
palate.

During the first part of the second period of deglutition,
the soft palate is slightly raised, being pressed upward by
the morsel of food. This fact has been observed in cases in
which the parts have been exposed by surgical operations,1 and
was demonstrated by M. Debrou, who passed a tube along
the floor of the nares to the pharynx, and noted a sudden de-
pression of the end projecting from the nose with each act
of swallowing, as though the soft palate struck suddenly
against the other extremity.2 This mechanism has also
been observed in the human subject by Bidder and Kobelt.
In this case — a young man who had lost the superior maxil-
lary bone, as well as the zygoma — the soft palate could be
observed from its superior surface ; and at each movement of

1 BEUARD (op. cit., tome ii., p. 25) cites a case of this kind observed by Rid-
der.

tt DEBROU, Theses de VEcole de Medecine de Paris, 1841, No. 266, p. 8.

DEGLUTITION. 193

deglutition., the palate, naturally inclined downward, became
more horizontal, and the posterior wall of the pharynx came
forward to meet it. The same movement of the pharynx
was observed by Kobelt in the case of a soldier who re-
ceived a severe sabre-cut in the neck.1

"While the food is passing the pharynx, the palato-pharyn-
geal muscles, which form the posterior pillars of the soft palate,
are in a state of contraction by which the edges of the pillars
are nearly approximated, forming, with the uvula between
them, almost a complete diaphragm between the postero-
superior and the antero-inferior parts of the pharynx. This,
with the application of the posterior wall of the pharynx
to the superior face of the soft palate, completes the protec-
tion of the posterior openings of the nasal fossae. The fact
that the posterior pillars are thus contracted and approxi-
mated during deglutition may be easily verified by sim-
ply watching these parts with a mirror during an effort at
swallowing. In the following case, observed by Berard, it
was shown that the muscular action of the soft palate was
absolutely necessary to the protection of the nares, particu-
larly in swallowing liquids : A young lady was aifected
with complete paralysis of the velum, wrhich allowed liquids
to return so freely by the nose in swallowing that she
was obliged to retire from observation whenever sh.e drank.2

1 BECLARD, Traite Elementaire de Physiologic Humaine, Paris, 1859, p. 60.

* Op. cit., p. 24.

In a late" article by M. Moura on the mechanism of deglutition, published in
the Journal de I1 Anatomic et de la Physiologic, there are some interesting obser-
vations upon the function of the velum of the palate in man and in the inferior
animals. While M. Moura fully recognizes the mechanism by which the velum
closes the posterior nares, in man, and shows that any interference with its func-
tions seriously disturbs the act of deglutition, he has found that the velum of the
palate could be entirely removed in the dog without any such result ; the animal
accomplishing the deglutition of both solids and liquids without difficulty and
without any return of these matters by the nares. This he explains by certain
important anatomical differences between the organs of deglutition in man and
in the dog. (HouRA, Memoire sur VActe de la Deglutition. — Journal de VAnato-
mie et de la Physiologic, Paris, 186Y, tome iv., p. 168.
13

194: DIGESTION.

Protection of the Opening of the Larynx, and Uses of
the Epiglottis in Deglutition. — The entrance of the smallest
quantity of solid or liquid foreign matter into the larynx
produces violent and distressing cough. This accident is of
not infrequent occurrence, especially when an act of inspira-
tion is inadvertently performed while solids or liquids are in
the pharynx. During inspiration, the glottis is widely opened,
and at that time only can a substance of any considerable size
find its way into the respiratory passages. Respiration is in-
terrupted, however, during each and every act of deglutition ;
and there can, therefore, be hardly any tendency at that time
to the entrance of foreign substances into the larynx. During
a regular act of swallowing, nothing can find its way into
the respiratory passages, so complete is the protection of the
larynx during the period when the food passes through the
pharynx into the oesophagus.

The situation of the epiglottis has naturally led physiolo-
gists to attribute to it great importance in preventing the
entrance of particles of food and liquids into the larynx. It
will be remembered that this cartilaginous leaf-like process
is attached to the anterior portion of the larynx, and is
usually erect, lying against the base of the tongue. In the
movements of the tongue and larynx incident to deglutition,
the epiglottis is necessarily applied to the superior face of
the larynx so as to close the opening. Although, during deg-
lutition, the glottis is covered in this way, it is necessary to
study closely all the conditions which are involved, and ascer-
tain what is the actual value of each of the various means by
which entrance of foreign bodies into the air-passages is
prevented; for this protection is accomplished by several
distinct provisions.

It is evident from the anatomy of the parts and the
necessary results of the contractions of the muscles of deglu-
tition, that while the food is passing through the pharynx,
the larynx, by its elevation, passes under the tongue as it
moves backward, and the soft base of this organ is, as it

DEGLUTITION. 195

•were, moulded over the glottis. With, the parts removed from
the human subject or from one of the inferior animals, we
can imitate the natural movements of the tongue and larynx,
and it is evident that this provision alone must be sufficient
to protect the larynx from the entrance of solid or semi-solid
particles of food ; particularly when we remember how the
alimentary particles are agglutinated by the saliva, and how
easy their passage becomes over the membrane coated with
a slimy mucus. Experiments on the inferior animals and
observations upon the human subject have conclusively set-
tled the question that the deglutition of all articles, except
liquids, is generally effected without difficulty, when the epi-
glottis has been removed or lost by accident or disease. The
same is true when, in addition, the intrinsic muscles of the
larynx have been paralyzed by the section of nerves, or even
when closure of the rima glottidis is forcibly prevented. It
has been shown, however, by the experiments of Longet, that
when the larynx is in part prevented from performing its
movement of ascension, the deglutition of a moist mass of
alimentary matter is effected with difficulty and is followed
by a sharp cough ; indicating the entrance of a certain quan-
tity of foreign matter into the air-passages.1

It is impossible for the muscles of the pharynx to con-
tract without drawing together the sides of the larynx, to
which they are attached, and assisting to close the glottis.
At the same time, as the movements of respiration are ar-
rested during deglutition, the lips of the glottis fall to-
gether ; as they always do except in inspiration. This fact
we have repeatedly observed in demonstrating the respira-
tory movements of the glottis; for when the larynx is
thus exposed, the animal makes frequent efforts at degluti-
tion. In addition to this passive and incomplete approxi-
mation of the vocal cords, it has repeatedly been observed
that the lips of the glottis are accurately and firmly closed
during each act of deglutition. This fact was first actually

1 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 112.

196 DIGESTION.

observed by Magendie in dogs, in his experiments on the
uses of the epiglottis in deglutition.1 Magendie believed
that this act was sufficient to protect the air-passages from
the entrance of all substances, liquid as well as solid. The
experiment of Longet, cited above, shows that this is not the
case; for if the movements of ascension of the larynx be
interfered with, liquids and moist articles are liable to find
their way into its cavity. The conclusions arrived at by
Magendie concerning the importance of the epiglottis in
deglutition have not been absolutely verified by the experi-
ments of others, nor are they carried out by observations on
the human subject; for when this part is entirely absent,
liquids are liable to penetrate the larynx.

The experiments of Longet with regard to the impor-
tance of the closure of the glottis itself in deglutition are
very interesting.2 This observer divided, first of all, the re-
current laryngeal nerves and the branch of the superior
laryngeal going to the crico-thyroid muscle, thus paralyzing
all the intrinsic muscles of the larynx. ISTothwithstanding
this, he found the occlusion of the glottis complete with
every act of deglutition, and demonstrated that this was due
to the powerful contraction of the inferior constrictors of the
pharynx, drawing together the sides of the larynx. In two
sheep and two dogs, after having removed a portion of the
trachea, he kept the glottis open by the introduction from be-
low of a dissecting forceps, and found that notwithstanding
the impossibility of closing the glottis, neither solids nor
liquids penetrated the trachea in swallowing. These ex-
periments show conclusively that although the glottis is
accurately closed during deglutition, this is not absolutely

1 MAGENDIE, Memoir e sur V usage de VEpiglotte dans la Deglutition, Paris,
1813, p. 3.

2 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. ,108, and Recherches
Experimentales sur les Fonctions de PEpiglotte et sur les Agents de Pocdusion de la
Glotte dans la Deglutition, le Vomissemcnt et la Rumination. — Archives Generates
de Mededne, Paris, 1841, 3me Serie, tome xii., p. 417 et seq.

DEGLUTITION. 197

necessary to the protection of the air-passages from the en-
trance of solids or liquids.

Longet justly attaches great importance to the exquisite
sensibility of the top of the larynx in preventing the entrance
of foreign substances. His experiments of dividing all the
nervous filaments distributed to the intrinsic muscles show
that their action is not essential. But on division of
the superior laryngeal, the nerve which gives sensibility to
the parts, he found that liquids occasionally passed in small
quantity into the trachea. This is attributed to the want
of sensibility in the mucous membrane above the glottis:
" for the animal is not aware in time of the presence of liquid
which may accidentally get into the supra-laryngeal cavity,
the occlusion of the glottis is sometimes too tardy and does
not take place until after the passage of the liquid ; or, again,
the animal, instead of then making a sudden expiration,
makes an unseasonable inspiration which facilitates the in-
troduction of the foreign substance into the air-passages, and
the cough does not take place until this is already in contact
with the tracheal or bronchial mucous membrane." !

These experiments beautifully illustrate the conservative

1 Op. cit.j tome i., p. 110. The two most elaborate and interesting articles
on the occlusion of the glottis in deglutition are those of Magendie and Longet.
The memoir of Magendie was presented to the first class of the Institute of France
in March, 1813. It contains the first experiments on record concerning the uses
of the epiglottis in deglutition, and the effects of its removal in the inferior animals.
The very elaborate memoir of Longet was published in the Archives Generates,
in 1841. Magendie showed that section of the inferior laryngeal nerves, para-
lyzing all the muscles of the larynx except the arytenoid and crico-thyroid, did
not interfere with deglutition, even in the case of liquids ; while after section of
the superior laryngeals, the deglutition of liquids was frequently followed by con-
vulsive cough. From this he concluded that the muscles animated by the supe-
rior laryngeal nerves were chiefly concerned in protecting the glottis. The later
and more minute experiments of Longet, however, proved this conclusion to be
an error. He showed that the cough occurred after the deglutition of liquids,
when the sensitive filaments of the superior laryngeals had been divided leaving
the muscular branches intact ; and he demonstrated that the difficulty lay in the
loss of sensibility of the mucous membrane, and not in paralysis of the crico-
thyroid muscles.

198 DIGESTION.

function of the acute sensibility of the mucous membrane
above the glottis. No foreign substance can find its way
into the air-passages by simply dropping into the cavity situ-
ated above the vocal cords when respiration is interrupted,
but can only enter by being drawn in forcibly and suddenly
with an act of inspiration, when the glottis is widely opened.
It is now well known to the practical physician that direct
applications cannot be made to the interior of the larynx,
unless an instrument be suddenly introduced with the inspi-
ratory act ; and at this time, a little dexterity will enable an
operator to introduce bodies of considerable size below the
vocal cords.

Functions of the Epiglottis. — Before the experiments of
Magendie, in 1813, physiologists were generally of the opin-
ion, judging from anatomical relations, that the epiglottis
had the function of protecting the larynx from the entrance
of particles of food during the second period of deglutition.
There were, however, some who did not entirely adopt this
view. Pinel and Percy, the reporters of a commission from
the Institute to examine the memoir of Magendie, mention
the fact that Guglielmini and Targioni had already noted, in
cases of persons in whom the epiglottis was entirely absent,
that no inconvenience was experienced during deglutition.1
Magendie extirpated the entire epiglottis in dogs, and found
that the animals swallowed liquids and solids without diffi-
culty, the act being very seldom followed by cough. The ob-
servations on deglutition were made an hour after the remo-
val of the epiglottis. In other animals the superior and
inferior laryngeal nerves were divided, thus paralyzing the
muscles of the glottis ; when the deglutition of liquids espe-
cially became difficult, and was followed generally by cough.
As the result of these observations, Magendie came to the

1 Rapport de la Classe dcs Sciences pJiysiques et mathematiques de FInatitut
Imperial de France, sur le Hemoire de M. Magendie, concernant Vusage de TEpi-
glotte dans la Deglutition. — Report attached to the memoir, p. 21.

DEGLUTITION. 199

conclusion, as we have already noted, that the larynx is pro-
tected during deglutition by closure of the glottis itself.

Although these experiments on animals were apparently
conclusive, the reporters of the Institute quoted observations
of Mercldin and Bonnet on the human subject, in which,
after the destruction of the epiglottis by disease, there existed
persistent difficulty in swallowing liquids. In these cases,
however, the reporters attribute the difficulty rather to " pa-
thological alterations of the true organs of deglutition than
to destruction of the epiglottis, which could not be affected
without involving changes unfavorable to their action." 3
As numerous pathological observations of this character have
been reported, the question could not be regarded as entirely
settled by the researches of Magendie. It was with the view
of determining this more rigorously, that further experiments
were instituted in 1841 by Longet.2

In investigating this question, Longet removed the epi-
glottis from six dogs. He found that in the animals kept
until the parts were perfectly cicatrized, more or less cough
followed the deglutition of liquids. One of these he kept for
six months, and found that when he drank milk or water
cough never failed to follow. The same fact was noted in
three of the animals that were killed on the nineteenth day,
and in one that was killed on the thirtieth day. In all, the
complete excision of the epiglottis was verified by post-mor-
tem examination. In one of the animals, killed two days
after the operation, that generally swallowed liquids without
coughing, there was found a swelling at the base of the
tongue which projected over the larynx.3

It is evident from these experiments that the observations
of Magendie we're not sufficiently extended, as he does not

1 Ibid.

2 Op. dt.

3 LONGET, RechercJies Experimentales sur les Fonctions de Vfipiglotte et sur les
Agents d'occlusion de la Glotie dans la Deglutition, le Vomissement et la Rumina-
tion.— Archives Generalcs, Paris, 1841, 3me Serie, tome xii., p. 418 et seq., and
Traits de Physiologic, Paris, 1861, tome i., p. 105.

200 DIGESTION.

.report that they were continued after sufficient time had
elapsed for the parts to cicatrize. At all events, it is neces-
sary, in this instance, to confirm the results of experiments
on animals by observations on the human subject.

Several cases of loss of the epiglottis in the human sub-
ject are quoted by Longet in support of his view that this
part is necessary to the complete protection of the air-pas-
sages, particularly in the deglutition of liquids. Two of the
most striking of these cases were observed by Larrey in
Egypt. One of these was the case of General Murat, who
was wounded by a ball passing through the neck from one
angle of the jaw to the other, cutting off the epiglottis, which
was expelled by the mouth. In this instance, the difficulty
in the deglutition of liquids was so great, that it became
necessary to introduce them through a tube passed into the
oesophagus. In the other case, the epiglottis was likewise en-
tirely removed by a wound and was preserved and presented to
the surgeon. In this instance, the difficulty in the deglutition
of liquids was even greater than in the former ; each effort at
swallowing being followed by convulsive and suffocating
cough. This difficulty persisted after the parts had become
completely cicatrized. In these cases it is possible that
the injury to muscles and other parts from such severe
wounds might interfere with the movements of the lar-
ynx or the closure of the glottis, and thus disturb deg-
lutition. In a case in which the epiglottis had entirely
sloughed away as a consequence of syphilitic disease,
which has already been referred to in the previous vol-
ume,1 the difficulty in swallowing liquids, though suffi-
ciently well marked, was by no means as great as in the
cases mentioned above. The difficulty in swallowing was
noted as not great, but the patient swallowed liquids more
easily than solids. The difficulty consisted of cough and loss
of breath, as the patient described it. It was less when arti-
cles were swallowed while the patient was in the recumbent

' ' See vol. i., p. 359.

DEGLUTITION. 201

posture, and food and drink were habitually taken in that
position. At the time that this patient, a female, was in the
Bellevue Hospital, under the observation of Dr. Flint, the
deglutition was improving. Dr. Flint noted that after she
had been in the hospital a few days, on causing her to swal-
low in his presence, the act of deglutition was performed
with a certain deliberation but without difficulty. An exam-
ination of the parts with the laryngoscope was made by Dr.
Church, in the presence of Dr. Flint and Dr. Dalton : " The
absence of the epiglottis was determined by sight. The
vocal cords were distinctly seen. The little excrescences
described as apparent to the touch were visible." a

In the case just described, there was not a constant and
considerable difficulty in deglutition ; but it is stated that
difficulty had existed, undoubtedly from the passage of arti-
cles into the larynx ; and when no such accident took place
the act was performed with a " certain deliberation." It is a
curious fact, also, that when the difficulty in swallowing was
considerable, deglutition was accomplished most easily in the
recumbent posture, in which the tendency of particles of
food to pass into the larynx must have been much lessened.

While, with attention on the part of the subject, the lar-
ynx may frequently, and perhaps generally, be protected
from the entrance of foreign substances during deglutition
after loss of the epiglottis when other parts are not affected,
a study of the numerous cases of this lesion as the result of
disease or injury shows that the epiglottis is by no means so
inefficient in the protection of the larynx as was supposed by
Magendie. Still it is but one of the means which have been
provided for this end.

Since the air-passages have been so fully explored by
means of the laryngoscope, this instrument has been used to
a certain extent in the study of the phenomena of deglutition.

1 The points in the history of this case bearing on the functions of the epi-
glottis in deglutition were taken from the hospital records of Dr. Flint, by whom
they were personally noted.

202 DIGESTION.

In July, 1865, a note was presented to the French Academy
of Sciences, giving the results of experiments by Dr. Krisha-
ber on the mechanism of deglutition as studied by auto-laryn-
goscopy, followed by a note on the same subject by M. H.
Guinier.1 Dr. Krishaber, as the result of his observations,
gives the following conclusions :

" 1st. In the act of deglutition the alimentary bolus passes
in one of the pharyngeal grooves, over one of the sides of the
epiglottis tilted by the elevation of the larynx ; the bolus
thus arrives at the oesophagus at the moment when, by the
contraction of the constrictor muscles, the pharynx is short-
ened and brought in front of the mass.

" 2d. The deglutition of liquids is effected in the same
manner ; these passing, however, quite frequently upon the
epiglottis itself, which happens very rarely with solid ali-
ments.

" 3d. A quantity — extremely small, it is true — of liquid
engages itself during normal deglutition around the border
of the epiglottis, and moistens the mucous membrane of the
larynx and even of the vocal cords.

"4th. In gargling, the larynx being widely opened, a
larger quantity finds its way into the vocal organ.

" 5th. An alimentary bolus may be easily tolerated in
the respiratory passages ; that is to say, in the larynx, as far
as the vocal cords, and even in the interior of the trachea.

" 6th. The sensibility of the trachea to the impression of
foreign bodies is infinitely less than that of the larynx.

" Tth. Hard and cold bodies, as, for example, a sound, are
not tolerated in the respiratory passages ; while any soft body,
which can adhere to the mucous membrane and has a tem-
perature like that of the parts touched, is easily tolerated in
the respiratory passages and kept in the trachea many
minutes without producing the slightest cough."

These observations confirm the views of Longet and
others concerning the passage of alimentary substances

1 Gazette Medicate de Paris, 15 juillet, 1865, p. 435.

DEGLUTITION. 203

down the pharynx by the sides of the epiglottis ; and in that
case, liquids would almost certainly pass around the borders
in quantity sufficient to moisten the mucous membrane be-
low. It must be remembered, however, that the sensibility
of the air-passages is very unequal in different persons, and
that it may be considerably modified by education of the
parts. This should make us hesitate to accept the view
that, in gargling, the larynx receives a quantity of li-
quid, and that an alimentary bolus may be tolerated in the
trachea for many minutes without coughing. Though this
may be true in the person of Dr. Krishaber, common experi-
ence shows that it is not generally the case.1

To sum up the mechanism by which the opening of the
larynx is protected during the deglutition of solids and
liquids, we have only to carefully follow the articles as they
pass over the inclined plane formed by the back of the
tongue and the anterior and inferior part of the pharynx.
As the food is making this passage in obedience to the con-
traction of the muscles which carry the tongue backward, draw
up the larynx, and constrict the pharynx, the soft base of the
tongue and the upper part of the larynx are applied to each
other, with the epiglottis, which is now inclined backward,
between them ; at the same time, the glottis is closed, in part
by the action of the constrictor muscles attached to the sides
of the thyroid cartilages, and in part by the action of its in-
trinsic muscles. If the food be tolerably consistent and

1 The note of M. H. Guinier mentions experiments on deglutition observed by
auto-laryngoscopy in which, by performing the act of swallowing slowly and imper-
fectly, so as not to close the pharynx, he was able to exhibit the phenomena to a
number of persons. He showed that the action of the epiglottis was not abso-
lutely necessary to protect the larynx during the passage of the alimentary bolus
from the pharynx to the O3sophagus, and that the passages could be protected by
simple closure of the vocal cords ; and that in gargling, the space above the superior
vocal cords was filled and the liquid agitated by the air as it was allowed to pass
slowly from the glottis. As regards the function of the epiglottis, it must be re-
membered that in these experiments, deglutition was not and could not be nor-
mal. The observations on gargling, however, seem very satisfactory.

204 DIGESTION".

united into a single bolus, it slips easily from the back, of the
tongue along the membrane covering the anterior and infe-
rior part of the pharynx ; but if it be liquid or of little consist-
ence, a portion takes this course, but another portion passes
over the epiglottis, being directed by it into the two grooves
or gutters by the side of the larynx.

It is by these means, together with those by which the
posterior nares are protected, that all solids and liquids are
directed to the oesophagus, and the second period of degluti-
tion is safely accomplished.

The third period of deglutition is the most simple of all.
It involves merely contractions of the muscular walls of the
oesophagus, by which the food is forced into the stomach.
The longitudinal fibres shorten the tube and slip the mucous
membrane, lubricated by its glairy secretion, above the
bolus ; while the circular fibres — by a progressive peristaltic
contraction from above downward — strip the food, as it were,
into the stomach. This shortening of the tube was well
illustrated in an observation on a female suffering under a
gastric fistula, by Halle ; who noted a protrusion of the mu-
cous membrane — which naturally undergoes no shortening —
into the stomach with each act of deglutition.1 The passage
of food down the oesophagus was for the first time closely
studied by Magendie ; who noted, in this connection, many
curious and important facts. In numerous experiments on
the lower animals, he observed that while the peristaltic
contractions of the upper two-thirds of the tube were imme-
diately followed by a relaxation which continued till the
next act of deglutition, the lower third remained contracted
generally for about thirty seconds after ^ the passage of the
food into the stomach. During its contraction, this part of
the oesophagus was hard, like a cord firmly stretched. This
was followed by relaxation ; and this alternate contraction
and relaxation continued constantly, even when the stomach

1 MAGENDIE, Precis filemeniaire de Physiologie, Paris, 1836, tome ii., p. 69.

DEGLUTITION. 205

was empty ; though during digestion, the contractions were
frequent in proportion to the quantity of food in the
stomach. The contraction was always increased by press-
ing the stomach and attempting to pass some of its contents
into the oesophagus.1 This provision is undoubtedly im-
portant in preventing regurgitation of the contents of the
stomach, especially when the organ is exposed to pressure, as
in urination or defecation. We have already noted the
action of the crura of the diaphragm, which have a tendency
to close the oesophageal opening during inspiration.2

The length of time occupied in the third period of deglu-
tition was noted by Magendie in the inferior animals, but we
have been unable to find any definite observations on this
point in the human subject ; though this would have been
easy in the cases of gastric fistula which, from time to time,
have come under the observation of physiologists. Magendie
found that the alimentary bolus sometimes occupied two or
three minutes in its passage, and that it was often momenta-
rily arrested in its course. It frequently seems as though we
were ourselves cbnscious of a very slow passage of food down
the oesophagus, and not infrequently a piece of bread or a
mouthful of liquid is taken to hasten it ; but it is not prob-
able that every alimentary bolus remains for two or three
minutes in the oesophagus, and liquids undoubtedly are
swallowed with considerable rapidity, as they can soon be
recognized in the stomach by their temperature. As the
lower part of the oesophagus is composed chiefly of un-
striped muscular fibres, it is probable that here the contrac-
tions are more gradual than in the upper portions.

As we have already had occasion to remark, the muscular
movements which take place during all the periods of deglu-
tition are peculiar. The first act is generally involuntary from

1 MAGENDIE, Memoire sur VCEsophage, lu d Vlnstitut de France, le 11 octo-
bre, 1813.

2 See Tol. i., Respiration, p. 370.

206 DIGESTION.

inattention, but is under the control of the will. The second
act is involuntary, when once commenced, but may be ex-
cited by the voluntary passage of solids or liquids beyond
the velum pendulum palati. It is impossible .to perform the
second act of deglutition unless there be some article, either
solid or liquid, in the pharynx. It is easy to make three or
four successful efforts consecutively, in which there is eleva-
tion of the larynx with all the other characteristic movements ;
but a little attention will show that with each act a small
quantity of saliva is swallowed. When the efforts have been
frequently repeated, the movements become impossible until
time enough has elapsed between them for the saliva to col-
lect. This fact was personally verified before writing this
paragraph; and it was demonstrated to be due to the ab-
sence of liquid ; for immediately after, an ounce of water
was swallowed without difficulty by sixteen successive move-
ments of deglutition. This experiment also shows the small
quantity of liquid (only half a drachm) necessary to excite
the contraction of the muscles concerned in the second act.

All the movements of deglutition, except those of the first
period, must be regarded as essentially reflex, i. e., depending
upon an impression made upon the afferent nerves distrib-
uted to the mucoup membrane of the pharynx and oesopha-
gus.1

The position of the body has little to do with the facility
with which deglutition is effected. Liquids or solids may be
swallowed indifferently in all postures. Berard states that a
juggler, in his presence, passed an entire bottle of wine from
the mouth to the stomach, while standing on his head.2 The
same feat we have lately seen accomplished with apparent
ease, by a juggler who drank three glasses of ale, while
standing on his hands in the inverted posture.

1 The study of the connection of deglutition with the nervous system is de-
ferred until we come to treat specially, in another volume, of the functions of the
nerves.

2 BERARD, Cours de Physiologic, Paris, 1849, tome ii., p. 32.

DEGLUTITION. 207

Deglutition of Air. — In the celebrated essay of Mageii-
die on the mechanism of vomiting, it is stated that as soon as
nausea commenced the stomach began to fill with air, so that
before vomiting occurred, the organ became tripled in size.
Magendie showed, furthermore, that the air entered the
stomach by the oesophagus, for the distension occurred when
the pylorus was ligated.1 In a subsequent memoir, the ques-
tion of the deglutition of air, aside from the small quantity
which is incorporated with the food during mastication and
insalivation, wras further investigated.2 It was found that
some persons had the faculty of swallowing air, and, by
practice, Magendie himself was able to acquire it, though it
occasioned such distress that it was discontinued. Out of a
hundred students of medicine, eight or ten were found able
to swallow air.

It is not very uncommon to find persons who have grad-
ually acquired this habit in order to relieve uncomfortable
sensations in the stomach ; and when confirmed, it occasions
persistent disorder in the process of digestion. Quite a num-
ber of cases of this kind are reported by Magendie, and in
several it was carried to such an extent as to produce great
distension of the abdomen. A curious case of habitual air-
swallowing is reported by Dr. Flint in his recent work on
the Practice of Medicine.3

Although the subject of air-swallowing properly belongs
to pathology, the fact that the muscles of deglutition are ca-
pable, in some individuals, of forcing air into the stomach, is
not without physiological interest.

1 MAGENDIE, Memoire sur le Vomissement, Paris, 1813, p. 13 et sea. In the
memoir on the oesophagus, an experiment is described in which a ligature was
applied to this canal near the diaphragm, and it was found that "the air,
which during the nausea tries to pass into the stomach, is arrested by the liga-
ture and distends the oasophagus." — (Op. cit., p. 10.)

3 MAGENDIE, Memoire sur la Deglutition de I'Air Atmospheriqiie, lu d Vln-
stitut, le 25 octobre, 1813.

3 FLINT, A Treatise on the Principles and Practice of Medicine, Philadelphia,
1866, p. 367.

CHAPTEE Yin.

STOMACH-DIGESTION—GASTRIC JUICE.

Physiological anatomy of the stomach — Peritoneal coat — Muscular coat — Mucous
coat — Glandular apparatus in the stomach — Gastric tubules — Mucous follicles
— Closed follicles — Gastric juice — Mode of obtaining the gastric juice — Gas-
tric fistula in the human subject — Secretion of the gastric juice — Secretion in
different parts of the stomach — Quantity of gastric juice — Composition of
the gastric juice — Organic principles of the gastric juice — Source of the acid-
ity of the gastric juice — Ordinary saline constituents of the gastric juice.

Physiological Anatomy of the Stomach.

THE most dilated portion of the alimentary canal, in man,
is the stomach. It serves the double purpose of a receptacle
for the food and an organ in which certain important diges-
tive processes take place. It is situated in the upper part
of the abdominal cavity, and is held in place by folds of the
peritoneum and by the oesophagus. Its form is not easily
described. It has been compared to a bagpipe, which it
resembles somewhat, when moderately distended. As we
should naturally suppose, from the fact that the stomach
periodically receives considerable quantities of solids and
liquids, its form and position are subject to great variations.
When empty, it is flattened, and in many parts its opposite
walls are in contact. "When moderately distended, its length
is from thirteen to fifteen inches, its widest diameter about
five inches, and its capacity one hundred and seventy-five
cubic inches, or about five pints.1 The parts usually noted

1 BRINTON, Cyclopaedia of Anatomy and Physiology, London, 1859, Supple-
ment, p. 308.

PHYSIOLOGICAL ANATO1IY OF THE STOMACH. 209

in anatomical descriptions are : a greater and a lesser cur-
vature ; a greater and a lesser pouch ; a cardiac, or cesopha-
geal opening; and a pyloric opening, which, leads to the
intestinal canal. The great pouch is sometimes called the
fundus.

The coats of the stomach are three in number : the peri-
toneal, muscular, and mucous. By some, the fibrous tissue
which unites the mucous to the muscular coat is regarded
as a distinct covering, and is called the fibrous coat.

Peritoneal Coat. — This is simply a process of the perito-
neum, similar in structure to the membrane which covers the
other abdominal viscera. It is a reflection of the membrane
which lines the general abdominal cavity, which, on the
viscera, is somewhat thinner than it is on the walls of the
cavity. Over the stomach, the peritoneum is from -^\^ to ¥£7
of an inch in thickness. It belongs to the class of serous
membranes, and consists of fibres of the white inelastic tissue,
mingled with a considerable number of elastic fibres. It is
closely adherent to the subjacent muscular coat, and is not
very abundantly supplied with blood-vessels and nerves.
Lymphatics have only been demonstrated in the subserous
structure. The surface of the peritoneum is everywhere
covered with regularly polygonal flattened cells of pavement
or tessellated epithelium, closely adherent to each other, and
presenting a perfectly smooth surface which is continually
moistened with a small quantity of watery secretion. An
important function of this membrane is to present a smooth
surface covering the abdominal parietes and viscera, so as
to allow of free movements of the viscera over each other and
against the walls of the abdomen. In the case of the nollow
viscera especially, this membrane, from its structure, must
give them considerable strength.

Muscular Coat. — Throughout the whole of the alimentary
canal, from the cardiac Opening of the stomach to the anus,
14

210 DIGESTION.

the muscular fibres forming the middle coat are of the invol-
untary, pale, or unstriped variety. These fibres, called some-
times muscular fibre-cells, are very pale, with faint outlines,
fusiform or spindle-shaped, and presenting an oval longitu-
dinal nucleus. They are very closely adherent by their
sides ; and are so arranged as to dove-tail into each other,
and form sheets of greater or less thickness, depending upon
the number of their layers. The muscular coat of the stomach
varies in thickness in different animals. In the human sub-
ject, it is thickest in the regio'n of the pylorus and is thin-
nest at the fundus. Its average thickness is about ^\ of an-
inch. In the pylorus, it is from T^ to y1^ of an inch thick,
and in the fundus from ^ to ^ of an inch.1

The muscular fibres exist in the stomach in two princi-
pal layers ; an external longitudinal layer and an internal cir-
cular layer, with a third layer of oblique fibres extending only
over the great pouch, which is internal to the circular layer.
The direction of the fibres in these layers can generally be
seen in a stomach which has been dried and inflated. The
longitudinal fibres are continued from the oesophagus, and are
most marked in the lesser curvature. They are not continued
very distinctly over the rest of the stomach. The circular
and oblique fibres are best seen when the organ has been
everted and the mucous membrane carefully removed. The
circular layer is not very distinct to the left of the cardiac
opening, over, the great pouch ; but in other parts is tolerably
regular. Toward the pylorus, the fibres become more numer-
ous, and at the opening into the duodenum, form a powerful
muscular ring, which is sometimes called the sphincter of
the pylorus, or the pyloric muscle. At this point they pro-
ject considerably into the calibre of the organ and cease
abruptly at the opening into the duodenum, so as to form a
sort of valve, presenting, when contracted, a flat surface
looking toward the intestine. The oblique layer takes the
place, in great part, of the circular fibres over the great

1 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 316.

MUCOUS COAT. 211

pouch. It extends obliquely over the fundus from left to
right, and ceases by rather a distinct line extending from the
left margin of the oesophagus to about the junction of the
middle and last third of the great curvature. This anatom-
ical fact is interesting, for it is at about the point where the
oblique layer of fibres ceases that the stomach becomes con-
stricted during the movements which are incident to diges-
tion, dividing the organ into two tolerably distinct compart-
ments.

The blood-vessels of the muscular coat are quite numer-
ous, and are arranged in a peculiar rectangular network,
which they always present in the non-striated muscular tis-
sue. The nerves belong chiefly to the sympathetic system,
and are demonstrated with difficulty.

Mucous Coat. — As we pass from the oesophagus to the
stomach, a very marked change takes place in the character
of the mucous membrane.- The white, hard appearance of
the oesophageal lining, due to its covering of pavement epi-
thelium, abruptly ceases, presenting a sharply defined, den-
tated border ; and the membrane of the stomach is soft,
velvety in appearance, and of a reddish-gray color. In some
of the inferior animals, as the horse, the characteristic mem-
brane of the oesophagus is prolonged into the stomach and
forms a large white zone around the cardiac opening, with ab-
ruptly defined edges, contrasting strongly with the rest of the
lining membrane of the stomach.

The mucous lining of the stomach is loosely attached to
the submucous muscular tissue, and is thrown into large
longitudinal folds, which become effaced as the organ is dis-
tended. When the muscular coat of the stomach is in a con-
dition of cadaveric rigidity, the longitudinal folding of the
mucous membrane is very marked. If the mucous mem-
brane be stretched, or if the stomach be everted and dis-
tended, and the mucus, which always exists in greater or less
abundance over the surface, be gently removed under a

212 DIGESTION.

stream of water, the membrane will be found marked with
innumerable polygonal pits or depressions, enclosed by
ridges, which in some parts of the organ are quite regular.
These are best seen with the aid of a simple lens, as many
of them are quite small. The size of the pits is very va-
riable, but the average is about ^ of an inch. This ap-
pearance is not distinct toward the pylorus ; the membrane
here presenting irregular conical projections, and some well-
marked villi resembling those found in the small intestine.
The surface of the mucous membrane is covered with co-
lumnar or prismoidal epithelium ; the cells being tolerably
regular in shape, with a clear nucleus and a distinct nucleolus.
The thickness of the mucous membrane of the stomach
varies in different parts. It is usually thinnest near the
oesophagus, and thickest near the pylorus. Its thinnest
portion measures from -f-% to •£-$ of an inch ; its thickest por-
tion from y1^ to y1^ of an inch ; and the intermediate portion
about ^4- of an inch.

Glandular Apparatus of the Stomach. — Extending from
the bottoms of the pits in the mucous membrane of the stom-
ach to the submucous areolar tissue, are immense numbers
of tubular glands. These are generally arranged in tolera-
bly distinct groups surrounded by fibrous tissue ; each group
belonging to one of the polygonal depressions. The tissue
which connects the tubes is dense, but not abundant. The
researches of Wasmann, Todd and Bowman, Kolliker, Bon-
ders, Brinton, and others have shown marked differences in
the anatomy of the glands and follicles of the stomach in
different parts of the organ, which are particularly interest-
ing, as they are supposed to correspond with differences in
the function of various parts of the mucous membrane.
There are, indeed, two distinct varieties of follicular glands :
the gastric tubules, found throughout the organ, except in
the pyloric portion ; and the mucous follicles, found in the
pyloric portion. These demand special consideration, as the

GASTRIC TUBULES. 213

former are supposed to secrete the gastric juice and are ac-
tive only during digestion, while the latter secrete a glairy
mucus, which is not produced specially during digestion and
which has no distinct digestive function with which we are
acquainted.

Gastric Tubules. — These are the organs , sometimes de-
scribed under the name of peptic glands, or stomach-glands.
In the large middle zone of the stomach, the tubes are simple,
extending through the entire thickness of the mucous mem-
brane. Their average length is about ^ of ari inch, and
their diameter is from Ti¥ to -3 £¥ of an inch. They are com-
posed of a delicate, structureless, basement membrane, with
the upper fourth or fifth lined with a continuation of the
general columnar epithelial covering of the stomach, and the
lower portion filled with, rather than lined by, hexagonal,
soft, secreting cells, called the stomach or peptic cells. These
cells have a nucleus and nucleolus, contain numerous
rather large oval granules, and are about T^Vo- of an inch
in diameter. This is the general character of the tubes over
the greater part of that portion of the mucous membrane
which secretes the gastric juice. These tubes readily un-
dergo post-mortem alteration, and, in the human subject,
are only to be seen satisfactorily in the fresh stomachs of sub-
jects who have died suddenly, having previously been in a
condition of perfect health.

Around the cardiac opening of the stomach, are compound
tubes, composed of essentially the same anatomical elements
as the simple tubes, and undoubtedly endowed with the
same function.1 These commence by a short tube, or duct,

1 Tubes of this kind are described and figured by Kolliker (Manual of Hu-
man Microscopic Anatomy, London, 1860, p. 320); but Sappey (Traite tfAna-
tomie Descriptive, Paris, 1857, tome iii., p. 120) attributes this to an illusive ap-
pearance produced by a super-position of different tubes, and asserts that such
glands certainly do not exist in man. The appearances described by Kolliker
have been often found by other observers, and there can be little doubt that
compound follicles exist just around the cardia ; but they probably are not found
in other parts of the mucous membrane.

214 DIGESTION.

lined with columnar epithelium, occupying from one-third to
one-half of the thickness of the mucous membrane. Below,
it branches abruptly into from four to seven smaller second-
ary tubes, which are lined with glandular epithelium simi-
lar to that found in the simple glands. Generally the large-
sized cells of glandular epithelium produce varicosities in the
tubes which give them a peculiar and characteristic appear-
ance— an appearance which is sometimes observed also in
the simple tubes. In both of these varieties of tubes, we
sometimes find granular matter and some fatty particles ;
though these are not always natural, as the delicate stomach-
cells are frequently destroyed by the fluid in which the prep-
aration is made, and break down into granular matter.

. Mucous Follicles. — "Near the pyloric extremity of the
stomach, where the mucous membrane is decidedly paler
than over the rest of the organ, the character of the tubular
glands undergoes a decided change. In the first place, the
orifices by which they open into the stomach are very much
larger, being about twice the size of the openings of the true
stomach-tubes. As the mucous membrane is here thicker
than in other situations, the follicles are correspondingly
longer. As a rule, they are compound ; but they do not com-
mence to divide until they have passed through about five-
sixths of the thickness of the membrane, when they break
up into from three to six small secondary tubes. The im-
portant peculiarity about these tubes is that many of them
are lined throughout with columnar epithelium, and are
everywhere deprived of the peculiar cells found in the true
stomach-tubes.

In some recent investigations by Prof. J. C. Dalton into
the anatomy of different parts of the stomach of the pig, most
of which we were enabled by the kindness of Prof. Dalton
to verify with him, the following results were arrived at:

" In the stomach of the pig the mucous membrane in the
neighborhood of the pylorus is moderately thick and of a

MUCOUS FOLLICLES. 215

light color. The villi upon its free surface are highly devel-
oped, being long, slender, often compound, and approximat-
ing in appearance, when simple, very much to the villi of
the small intestines. The tubules of the mucous membrane,
TiT of an inch in diameter, run vertically through its whole
thickness and terminate at various depths. The shorter ones
are without branches, nearly straight, and terminate by sim-
ple rounded extremities. The longer ones give off several
lateral branches near their lower extremity, the upper
branches being longer, the lower ones shorter, the whole
group collected into a little mass or lobule. These tubes are
lined with epithelial cells, mostly of a cylindrical form, but
of very small size, closely packed, and evidently glandular in
character.

" In the neighborhood of the cardia, the mucous mem-
brane is quite thin and pale, without any well-developed vil-
lous projections. In the superficial portion, the tubules are
very wide cylinders, lined with large, clear, well-defined cells
of cylinder-epithelium, branching below usually into two
smaller tubes, also lined with cylinder-epithelium. These
tubes become still further reduced in size until they are a lit-
tle narrower than the tubules of the pyloric portion, when they
become lined with small glandular epithelial cells, and ter-
minate below in rounded extremities. The secreting tubules
of this portion of the stomach are much shorter than those
of the pyloric portion.

" In the middle portion of the stomach, especially along
the great curvature, the mucous membrane is considerably
thicker than elsewhere and is of a dark-red color. The villi
upon its surface are perfectly distinct, though not so long
and slender as in the pyloric portion. The gastric tubules
are much longer than in any other part, and more closely
bound together at the bottom, so that they are separated
with much greater difficulty. They are rather wider than
the other secreting tubules, and contain, besides the ordi-
nary smaller epithelium, an abundance of large, rounded,.

216 DIGESTION".

granular, and nucleated cells about three times the size of the
glandular epithelial cells from either the cardiac or pyloric
tubules. These cells appear to fill the cavity of the tu-
bules, and give a varicose appearance to their lateral out-
lines." 1

Todd and Bowman, who were among the first to point
out the important diiferences in the glandular structures in
different parts of the stomach, state that " for the most part,
these prolongations of the cells — or, as we shall term them,
pyloric tubes — end at length in very short and diminutive
true stomach tubes ; but we have likewise found them ter-
minating in either flask-shaped or undilated extremities,
lined throughout with the sub-columnar variety of epithe-
lium."2 Kolliker, who has also specially investigated this
subject, states that the stomach-cells are entirely wanting in
the pyloric tubes ; 3 and Brinton, as the result of extended ob-
servations, makes the same assertion.4 However this may be,
the observations of Kolliker and Donders on the human
stomach have shown that the active principle of the gastric
juice can only be produced by the stomach-cells, and does
not exist in the pyloric extremity.5

Todd and Bowman have found that the mucus which
generally covers the membrane of the stomach, filling up the
pits or depressions, is continued into the upper part of the
tubes, which it nearly fills, as though it had gradually oozed

J Written communication to the author.

2 TODD AND BOWMAN, The Physiological Anatomy and Physiology of Han,
Philadelphia, 1857, p. 549.

3 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 321.

4 Cyclopaedia of Anatomy and Physiology, London, 1859. Supplementary
volume, p. 322.

6 KOLLIKER, loc. cit. In a note by Dr. Da Costa, the editor of the American
edition (Philadelphia, 1854, p. 506), it is stated that Prof. Kolliker had an op-
portunity of examining the human gastric mucous membrane in a fresh and nor-
mal state in a case of suicide by drowning. In this case, the differences in the
anatomy of the tubes in the cardiac, the middle, and the pyloric zone were fully
established.

GASTRIC JUICE. 217

from the columnar cells at the sides, leaving a small central

Three observers, Middeldorph, Briicke, and Kolliker,
almost simultaneously, each one ignorant of the observations
of the others, noted in the submucous tissue the presence of
a few involuntary muscular fibres surrounding the ccecal
extremities of the stomach-tubes.8 These are supposed to be
active in discharging the contents of these tubes during the
secretion of the gastric juice.

Closed Follicles. — In the substance of the mucous mem-
brane, between the tubes and near their coecal extremities, are
occasionally found closed follicles, like the solitary glands
and patches of Peyer of the intestines. These are not
always present in the adult, but are generally found in
children. They are usually most abundant over the
greater curvature, though they may be found in other situa-
tions. In their anatomy they are identical with the closed
follicles of the intestines, and do not demand special consid-
eration in this connection.

Gastric Juice.

At the present day it seems profitless to argue the ques-
tion of the existence of a digestive fluid in the stomach ; and
the discussions of the earlier physiologists as regards the
possibility of the existence of a fluid capable of dissolving the
articles of food have only an historical interest. It is im-
portant, however, to follow the experiments by which the
existence and the properties of the gastric juice were brought
to light, as the discovery of this fluid marks the commence-
ment of our definite knowledge concerning the process of
digestion.

In 1752, while the controversy between those who be-
lieved that the stomach simply triturated the food, and

1 Op. dt.

a LONGET, Traite dc Physiologic, Paris, 1861, tome i., p. 180.

218 DIGESTION.

those who suspected the existence of a solvent fluid was at it8
height, Reaumur first obtained what is now known as the
gastric juice, and demonstrated some of its solvent properties.
In a paper presented to the Academy of Sciences of Paris,
on the process of digestion in birds, he showed that meat
enclosed in a tin tube so arranged as to permit the entrance
of liquids, when forced into the stomach of a buzzard, became
softened and partly digested after remaining in the organ for
several hours. Substituting small pieces of sponge for the
meat, he obtained a few grains of gastric juice, in which
he noted a well-marked acid reaction ; but the quantity ob-
tained was not sufficient to allow of any satisfactory experi-
ments on artificial digestion.1 This was the first time that
the presence of a solvent fluid in the stomach had ever been
experimentally demonstrated, and the fluid was the first spe-
cimen of gastric juice ever obtained. The experiments on
birds were repeated by Reaumur, in an imperfect manner,
on dogs and sheep, with analogous results.

The celebrated observations of Stevens, in l^YT, were
even more conclusive with regard to the presence of solvent
fluids in the alimentary canal. He had under observation a
juggler, who, in his performances, was in the habit of swal-
lowing stones and other hard articles. For the purpose of
ascertaining whether food could be dissolved in the alimentary
canal if removed from all triturating action, Stevens con-
structed little hollow balls of silver and of ivory, pierced
with numerous small holes, and capable of being opened by
a screw in the middle, which he caused the man to swallow
after they had been filled with various articles.2 After a
number of hours, from thirty-six to forty-eight, the balls
were passed by the anus entirely empty, except when they
had been filled with hard grains, which were only a little

1 REAUMUR, Sur la Digestion des Oiseaux, Second Memoire. — Histoire de
I* Academic Royale des Sciences, Paris, 1752, pp. 461-495.

3 STEVENS, De Alimentorum Concodione, Edinburgh, 1777, in SMELLIE'S Thes.
Med., quoted by TIEDMANN AND GMELIN, op. cit., premiere partie, p. 365, note.

GASTRIC JUICE. 219

softened. A few years later, the experiments of Reaumur
were reproduced by Spallanzani; who caused animals to
swallow food contained in perforated tubes and obtained the
gastric juice by means of sponges, extending the observations
to dogs and cats and in some instances experimenting on
his own person. He swallowed, for example, little netted
bags of thread, and on one occasion a small perforated
wooden tube, filled with food, which he found always passed
empty by the anus.1

The experiments of Reaumur, Stevens, and Spallanzani
demonstrated the existence of the gastric juice. They were
followed by the elaborate investigations of Prout, Tiede-
mann and Gmelin, Leuret and Lassaigne, and others, by
which various of the properties of this fluid were established ; a
but our definite knowledge of its most important physiologi-
cal properties dates from the observations of Dr. Beaumont
on the Canadian, Alexis St. Martin, who had a large fistu-
lous opening into the stomach.3 These observations were
commenced in May, 1825, and were continued for a number
of years. The first publication of them was in the Phila-
delphia Medical Recorder , in 1826.

Mode of obtaining the Gastric Juice. — The ingenious ex-
periments of Dr. Beaumont upon the case of St. Martin gave
an impulse to the study of digestion, and pointed out the
way in which the action of the gastric juice could be inves-

1 SPALLANZANI, Opuscules de Physique, Animate et Vegetale, Augmentes de ses
Experiences mi? la Digestion, traduits par Jean Senebier, Pavie, 1787, tome ii.
pp. 431, 483, 619, 642, and 645.

2 LEURET ET LASSAIGNE, JRecherches Physiologiques ct Chimiques pour servir d
VHistoirs de la Digestion, Paris, 1825. These authors give an analysis of the gas-
tric juice, which corresponds pretty nearly with the analyses of the more recent
physiological chemists. They noted the presence of lactic acid, hydrochlorate of
ammonia, chloride of sodium, animal matter soluble in water, mucus, and phos-
phate of lime. (p. 113.)

3 Experiments and Observations on the Gastris Juice, and the Physiology of
Digestion, by WILLIAM BEAUMONT, M. P., Surgeon in the U. S. Army, Plattsburg,
1833.

220 DIGESTION.

tigated. The fact that Dr. Beaumont noted the action of
human gastric juice upon all the ordinary articles of food
enabled physiologists to compare with it the properties of the
secretion obtained from the inferior animals, an indispen-
sable condition in the study of the digestive fluids. In 1843,
Blondlot published a treatise on digestion, in which he gave
the results of experiments on dogs with fistulous openings
into the stomach.1 This observer is generally spoken of as
the first to obtain the gastric juice by the establishment of
a fistula into the stomach in the inferior animals ; but Lon-
get states that in December, 1842, Dr. Bassow read a paper
before the Imperial Society of Naturalists of Moscow, which
was published in the Bulletin for that year, in which
he gave an account of a number of successful attempts to
establish a gastric fistula in dogs.2 In the animals operated
upon by Bassow, the openings were not kept open by a can-
ula, and he was much annoyed by their tendency to close.
There is no reason to suppose that Blondlot was aware of the
experiments of Bassow, which, as Longet remarks, were little
known to physiologists, and, as far as we are aware, were not
quoted in works on physiology before the publication of
Longet's treatise in 1861. With some slight modifications
in the operative manipulations, the method of Blondlot is the
one now in common use.

The establishment of a permanent gastric fistula is now
one of the simplest and most common of the physiological
operations. The dog is the animal generally used ; and from
the fact that he is not very subject to peritonitis the opera-
tion almost always ends in recovery, and the animal can be
trained so that the juice may be obtained in quantity and
with great facility. The operative procedure which we have
found most convenient is the following :

1 BLONDLOT, Traite Analytique de la Digestion, Paris, 1843.

2 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 190. Reference to
the experiments of Bassow is also made by Milne-Edwards, in his elaborate work
nowin course of publication (Lc$ons stir la Physiologic, Paris, 1862, tome vii., p. 13).

GASTEIC JUICE. 22 3

It is best to choose a dog of medium size, young, but
nearly, if not entirely full grown, in perfect health, and of
good disposition. Bringing the animal under the influence
of ether, he is to be held firmly on the back, and an incision
about two inches in length is made in the median line into
the abdominal cavity. This incision should be commenced
from half an inch to an inch below the ensiform cartilage.
Introducing the finger into the abdominal cavity, the stom-
ach can readily be felt, especially if it be moderately dis-
tended ; and with a pair of hooked, or bull-dog forceps, that
portion of the stomach nearest the wound may be seized and
drawn out of the abdomen. It is important to make the fis-
tula into that portion of the anterior wall of the stomach
which is nearest the wound, to avoid disturbance in the posi-
tion of the viscera ; and the organ is in the most favorable
position for the operation if it be moderately distended with
food.

A portion of the stomach being drawn out of the abdo-
men, a slit is made parallel to the longitudinal fibres, just
large enough to admit the canula.

A silver canula, about an inch and a quarter in length,
half an inch in diameter, and provided with a straight rim
or flange at each end about half an inch in width, is now
introduced into the stomach and firmly secured in place by
a ligature surrounding it and passed in and out through the
coats of the stomach near the lips of the wound, like the
string of a purse. This canula may be single, or as sug-
gested by Bernard, double, one-half screwing into the other
so that it may be elongated to twice the length it has when
closed. This is somewhat convenient, as the tube may be
introduced elongated, and when the swelling of the parts
has subsided, may be shortened by a key, so as not to pro-
ject beyond the abdominal walls.

After the canula has been firmly fixed in the stomach,
the tube, with one of its flanged ends projecting, should be
drawn to the upper part of the opening in the abdomen, and

222 DIGESTION.

the wound closed by sutures passed through the integument,
muscles, and peritoneum.

The dog will generally eat on the second or third day
after the operation ; and peritonitis — aside from the inflam-
matory action which agglutinates the stomach at the site of
the operation to the walls of the abdomen — rarely follows.
It is best to feed the animal sparingly a short time before
operating, as there is some difficulty in seizing the stomach
when it is entirely empty.

Having thus established a permanent fistula into the
stomach, after the wound has cicatrized around the canula,
the animal suffers no inconvenience, and may serve indefi-
nitely for experiments on the gastric juice. Many physiol-
ogists have been in the habit of exciting the flow of this
fluid by the introduction into the stomach of pieces of ten-
don, or hard indigestible articles, on the ground that the
fluid taken from the fistula, under these circumstances, is
unmixed with the products of stomach digestion ; but it has
been . shown that the quantity and character of the juice is
influenced by the nature of the stimulus which causes its se-
cretion ; and it is proper, therefore, to excite the action of the
stomach by articles which are relished by the animal. For
this purpose, lean meat may be given, cut into pieces so small
that they will be swallowed entire, and first thrown into
boiling water so that their exterior may become somewhat
hardened. The cork is then removed from the tube, which
is simply freed from mucus and debris, when the gastric
juice will begin to flow, sometimes immediately, and some-
times in from three to five minutes after the food is taken.
It will flow in clear drops or in a small stream for about
fifteen minutes, nearly free from the products of digestion.
At the end of this time it is generally accompanied with
grumous matter, and the experiment should be concluded if
it be desired simply to obtain the pure secretion. In fifteen
minutes, from two to three ounces of fluid may be obtained
from a good-sized dog, which, when filtered, is perfectly

GASTRIC JUICE. 223

clear; and this operation may be repeated three or four
times a week without interfering with the quality of the juice
or injuring the health of the animal.1

Although instances of gastric fistula in the human subject
had been reported before the case of St. Martin and have been
observed since that time, the remarkably healthy condition
of the subject and the extended experiments of so competent
and conscientious an observer as Dr. Beaumont have ren-
dered this case memorable in the history of physiology. It is
undoubtedly the fact that this is the only instance on record in
which pure, normal gastric juice has been obtained from the
human subject ; and it served a most important purpose as
the standard for comparison of subsequent experiments on the
inferior animals. The details of this case, condensed from
the monograph of Beaumont, are briefly the following :

Alexis St. Martin, a Canadian voyageur in the service of
the American Fur Company, eighteen years of age, of good
constitution and perfectly healthy, was wounded in the left
side by the accidental discharge of a gun loaded with duck-
shot. The wound was received on the 6th of June, 1822 ;
and the muzzle of the gun was not more than a yard distant
from the body. The contents of the gun entered posteriorly,
carrying away integument and muscles from a space the size
of the hand, with the anterior half of the sixth rib, fractur-
ing the fifth rib, lacerating the lower portion of the left lobe
of the lungs and the diaphragm, and perforating the stom-
ach. The patient was seen by Dr. Beaumont twenty-five or

1 Bernard recommends to make the fistula on the left side at the outer bor-
der of the rectus muscle. He introduces the canula forcibly through an opening
into the stomach made a? small as possible, and relics upon the contraction of the
walls of the stomach around the tube to prevent the passage of matters into the
peritoneal cavity. (Lemons de Physiologic Experirnentale, Paris, 1856, p. 385.)
Unless this part of the operation be performed with grsat care and exactness, it
is safer to employ the ligature. In collecting the juice, he simply fixes a bag of
rubber to the, canula after feeding the animal ; but the fluid is obtained more
satisfactorily by making the animal stand over a strong vessel, as a mortar. On
several occasions we have had dogs so trained as to stand on the table for the
proper time without requiring any attention.

224: DIGESTION.

thirty minutes after the accident, when the above facts were
noted, and an opening into the stomach was discovered
large enough to admit the forefinger. Extensive sloughing
took place ; and for seventeen days every thing that was swal-
lowed passed out at the wound, and nourishment was admin-
istered by the rectum. In the spring of 1824, the wound had
cicatrized, and the patient had perfectly recovered his
health ; but in the process of cure, seven pieces of cartilage
had come away, and three or four inches of the sixth rib, with
about half of the lower edge of the fifth rib, had been removed
by an operation. The perforation into the stomach was
irregularly circular in form, and about two and a half inches
in circumference. This opening was closed by a protrusion
of the mucous membrane of the stomach in the form of a
valve, which could readily be depressed by the finger so as
to expose the interior. This valve effectually prevented the
discharge of the contents of the stomach, which had annoyed
the patient previous to the winter of 1823-'24.

From May, 1825, to August of the same year, St. Martin
was under the observation of Dr. Beaumont, and submitted
to numerous experiments. At the end of that time, he re-
turned to Canada, and was lost sight of for four years, during
which time he married and became the father of two chil-
dren, " worked hard to support his family, and enjoyed ro-
bust health and strength." He then came again under the
observation of Dr. Beaumont, and continued in his service,
doing the work of a common servant, until March, 1831.
After this, he was under observation from time to time until
1836 ; all this time enjoying perfect health, with good diges-
tion, and having become the father of several more children.
The last published observations made upon this case were
in 1856.1

1 In the Philadelphia, Medical Examiner, numbers for July and September,
1856, is an account of some experiments made on St. Martin in May of the same
year. These observations were also published in the Journal de la Physiologic,
Paris, 1858, tome i., p. 144 etseq.

SECRETION OF THE GASTRIC JUICE. 225

The following was the method employed by Dr. Beaumont
in extracting the juice : The subject was placed on the right
side in the recumbent posture, the valve was depressed with-
in the aperture, and a gum-elastic tube, of the size of a large
quill, was passed into the stomach to the extent of five or six
inches. On turning him upon the left side until the opening
became dependent, the stimulation of the tube caused the se-
cretion to flow, sometimes in drops and sometimes in a small
stream. The quantity of fluid ordinarily obtained was from
four drachms to an ounce and a half. The usual time for
collecting the juice was early in the morning, before he had
eaten. It was remarked that under these circumstances
there was never an accumulation of gastric juice in the
stomach, and its flow was only excited by the stimulus of the
tube. It was also repeatedly observed that the introduc-
tion of alimentary principles, while the tube was in the
stomach, produced an almost instantaneous increase in the
flow.

Thanks to these opportunities for observing the action of
the human stomach, followed by the experiments of Blond-
lot and others on the inferior animals, now so common,
physiologists have become pretty well acquainted with the
phenomena which attend the secretion of the gastric juice.

Secretion of the Gastric Juice.

As the earlier observers were unacquainted with the laws
which regulate the production of secreted fluids as distin-
guished from those which contain only excrementitious
principles, their ideas concerning the secretion of the gastric
juice were necessarily indefinite. One of the most impor-
tant facts developed by Beaumont was that the normal sol-
vent fluid of the stomach is only produced in obedience to
the stimulus of food, during the natural process of digestion.
Recent advances in physiological chemistry have enabled ex-
perimenters to correct many errors in the observations of
Beaumont concerning the properties and action of the gastric
15

226 DIGESTION.

juice, but his descriptions of the phenomena which accom-
pany its secretion have been repeatedly verified.

During the intervals of digestion, the mucous membrane
is comparatively pale, -" and is constantly covered with a
very thin, transparent, viscid mucus, lining the whole in-
terior of the organ." 1 On the application of any irritation,
or, better, on the introduction of food, the membrane
changes its appearance. It now becomes red and turgid
with blood ; small pellucid points begin to appear in various
parts, which are, in reality, drops of gastric juice ; and these
gradually increase in size until the fluid trickles down the
sides in small streams. The membrane is now invariably
of a strongly acid reaction, while at other times it is either
neutral or faintly alkaline. The thin watery fluid thus
produced is the true gastric juice. Though the stomach
may contain a clear fluid at other times, this is generally
abnormal, is but slightly acid, and does not possess the
marked solvent properties characteristic 'of the natural secre-
tion. It has been shown by Beaumont, and his observations
have been repeatedly confirmed by experiments on the infe-
rior animals, that the gastric juice is secreted in greatest
quantity, .and possesses the most powerful solvent properties,
when food has been introduced into the stomach by the nat-
ural process of deglutition. Under these circumstances the
stimulation of the mucous membrane is general, and secre-
tion takes place from the entire surface capable of pro-
ducing the fluid. When any foreign substance, as the gum-
elastic tube used in collecting the juice, is introduced, the
stimulation is local, and the flow of fluid is comparatively
slight.2 It has been also observed that the quantity imme-
diately secreted on the introduction of food, after a long fast,

1 BEAUMONT/ op. cit., p. 103.

2 In endeavoring to obtain the pure gastric juice, Beaumont introduced a
gum-elastic tube into the stomach in the morning, when the organ was entirely
empty. Obtained in this way, it always required ten or fifteen minutes to collect
from one and a half to two ounces of fluid. (Op. tit., p. 106.)

SECRETION OF THE GASTEIC JUICE. 227

is always much greater than when food has been taken after
the ordinary interval.

While natural food is undoubtedly the proper stimulus
for the stomach, and while, in normal digestion, the quantity
of gastric juice is perfectly adapted to the work it has to
perform, it has been noted that savory and highly seasoned
articles generally produce a more abundant secretion than
those which are comparatively insipid. An abundant secre-
tion is likewise excited by some of the vegetable bitters. It
was observed by Blondlot that the effects of alkalies and acids
upon the secretion were entirely opposite. He states, as a
general proposition founded on experiments, that while acids
retard digestion, the action of alkalies is always to produce a
great increase in the quantity of normal gastric juice.1 He
also makes the general statement that alkalies promote the
flow of acid secretions, and vice versa; supposing, on this
principle, that the saliva tends to stimulate the flow of the
gastric juice, and the acid secretion from the stomach, passing
into the intestines, stimulates the flow of the alkaline fluids
poured into this part of the alimentary canal. Of the fact
that alkalies specially stimulate the gastric mucous membrane
there can be no doubt ; and it is probable that an abundant
flow of saliva and its thorough incorporation with the food
exerts, in this way, an important influence upon stomach-
digestion.

Impressions made on the nerves of gustation have a
marked influence in exciting the action of the mucous mem-
brane of the stomach. Blondlot found that sugar, introduced
into the stomach of a dog by a fistula, produced a flow of
juice much less abundant than when the same quantity was
taken by the mouth. To convince himself that this did not
depend on the want of admixture with the alkaline saliva,
he mixed the sugar with saliva and passed it in by the
fistula, when the same difference was observed.2 It is a cu-

1 BLONDLOT, Traite Analylique de la Digestion, Paris, 1843, p. 219.

2 Op. cit., p. 221.

228 DIGESTION.

rious fact that in some animals, particularly when they are
very hungry, the sight and odor of food will induce secretion
of gastric juice.1

The gastric juice is probably one of the most sensitive of
the secreted fluids to disturbing influences. It was remarked
by Beaumont that a febrile condition of the system, the de-
pression resulting from an excess in eating or drinking, and
even purely mental conditions, such as anger or fear, viti-
ated, diminished, and sometimes entirely suppressed the se-
cretion of the stomach. At some times the mucous mem-
brane became red and dry, and at others it was pale and
moist. In such morbid conditions, it is stated that drinks
were immediately absorbed, but that food remained in the
stomach undigested for twenty-four or forty-eight hours.2

It has also been shown by Bernard and others that vari-
ous foreign substances circulating in the blood readily pass
into the gastric juice ; and that in cases of organic disease
of the kidneys, and in animals in which the kidneys have
been extirpated, urea is for a time eliminated by the mu-
cous membrane of the stomach. The secretion is always
arrested by inflammation or active irritation of the mucous
membrane.

The influence of the nervous system on the secretion of
gastric juice, exerted particularly through the pneuiiio-gas-
tric nerve, is very marked and important, but its considera-
tion belongs properly to the section on the nervous system.

After the food has been in part liquefied and absorbed
and in part reduced to a pultaceous consistence, the secre-

1 There is considerable difference in different dogs as regards the facility with
which the flow of gastric juice may be excited. In some, the stomach is entirely
free from fluid during the intervals of digestion, and the gastric juice can only
be made to flow by the introduction of some "digestible article. Dr. Dalton men-
tions an example of this kind (Human Physiology, Philadelphia, 1864, p. 137).
In others, however, the reaction of the stomach is always acid, though it contains
hardly any fluid during the intervals of digestion, and an abundant secretion of
gastric juice may be induced by very slight stimulation.

2 Op. tit., pp. 107, 108.

SECRETION OF THE GASTRIC JUICE. 229

tion of gastric juice ceases ; the movements of the stomach
having gradually forced that portion of the food which is but
partially acted upon in this organ, or digested only in the
small intestines, out at the pylorus. The stomach is thus
entirely emptied, the mucous membrane becomes pale, its
reaction loses its marked acid character, and becomes neu-
tral or faintly alkaline.

Secretion in different parts of the Stomach. — The differ-
ences already noted in the anatomy of the mucous membrane
of the stomach in different parts of the organ, point to the
important question of a possible difference in the physiolo-
gical action of the secretions of different parts, particularly
the pyloric portion and the rest of the general surface. We
can learn definitely but little with regard to this point from
observations on the inferior animals, unless they be confirmed
in the human subject. The observations, however, of Kol-
liker, G-oll, and Bonders on the pig, are very satisfactory,
and subsequently were fully confirmed as regards the human
subject. It is well known that an acidulated infusion of the
mucous membrane of the stomach possesses, if properly pre-
pared, all the digestive properties of the true gastric juice ;
and that this is not the case with similar infusions of the
mucous membrane from any other parts. Kolliker, in ex-
periments on artificial digestion made in conjunction with
Dr. Goll, "on the gastric mucous membrane of the pig,
clearly showed that the two kinds of glands entirely differ in
respect of their solvent power ; inasmuch as those with the
round cells dissolved acidulated coagulated protein-compounds
in a very short time y those with cylindrical epithelium, on
the contrary, either did not operate at all, or produced a
slight effect only after a longer period" ' The same author
further states that these observations were confirmed by
Donders and himself in the human stomach. In 1842, Mr.
T. "W. King noted the peculiar solvent action of the fluid

1 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 321,
and in the American edition, 1854, p. 508.

230 DIGESTION.

from the cardiac portion of the stomach. This part he found
was always acid, while in other parts the reaction was vari-
able. ' He states that after death, there is a distinct line from
the right side of the cardiac opening to the great curvature,
which marks the division between that portion which se-
cretes the true gastric juice and has been acted upon after
death, and that which does not produce a solvent fluid.1

Although the character of the secretion in different parts
of the stomach is not the same in all animals, it must be ad-
mitted that in man, the mucous membrane of the stomach, in
what may be called the pyloric zone, does not secrete the true,
acid, solvent, gastric juice. In other words, this fluid is only
produced in those portions of the stomach in wThich the mucous
membrane is provided with tubes lined with cells of glandular
epithelium, or what have been called the stomach-cells.

In most of the modern works on physiology, allusion is
made to the probable quantity of gastric juice secreted in the
twenty-four hours. The estimates on this point can be only
approximative, even in the inferior animals, and they give no
definite information concerning the normal quantity in the
human subject. Bidder and Schmidt, Lehmann, Corvisart,
and others have made calculations of the probable quantity,
either by collecting the juice for a certain time and multi-
plying the quantity thus obtained by a number to represent
the whole twenty-four hours, or by ascertaining the amount

1 KING, Observations on the digestive Solution of the (Esophagus, and on the dis-
tinctive Properties of the two Ends of the Stomach. — Guy's Hospital Reports, Lon-
don, 1842, vol. vii., p. 147 et seq. The observations of Mr. King, being generally
upon subjects that had died of disease, are not as definite and conclusive as might
be desired ; but they are valuable as confirming the experiments of Dr. Wilson
Philip on rabbits, who showed that tho great pouch was the only part which
was digested post mortem, when the animals were killed after a full meal (An
Experimental Inquiry into the Laws of the Vital Functions, London, 1826, p.
131), and others who have also experimented on the inferior animals. In the
celebrated paper of John Hunter on Digestion of the Stomach after Death, read
before the Royal Society in June, 1772, it was noted that the softening was
always at the great end ( Works, Philadelphia, 1840, vol. ii., p. 147, and Observa-
tions on certain parts of the Animal (Economy, London, 1792, p. 229).

SECRETION OF THE GASTEIO JUICE. 231

of fluid required to digest a certain weight of food, and esti-
mating from this the quantity necessary to dispose of all the
food taken during the day. Both of these methods are mani-
festly incorrect. In the first, the intermittency of the secre-
tion is not taken into account ; and in the second, it is incor-
rectly assumed that digestion out of the body is accomplished
precisely as it takes place in the stomach.

Dr. Beaumont was sometimes able to collect, in from ten
to fifteen minutes, two ounces of pure gastric juice, simply
by the stimulation produced by the gum-elastic catheter nsed
in the operation ; but he expressly states that in this case
only a part of the mucous membrane is excited to secretion,
while the flow is very much increased by the introduction
of food by the mouth, which produces a general excitation
of the secreting membrane. Assuming that two ounces can
be collected, under the most favorable circumstances, in ten
minutes, and that stomach-digestion continues for two hours,1
the quantity secreted during the digestion of an ordinary
meal would amount to twenty-four ounces. When we con-
sider that the natural stimulus of food produces a general
secretion, amounting to at least three or four times that pro-
duced by the simple introduction of the catheter, and that it
is manifestly impossible to collect all that is secreted, even
when nothing but the catheter has been introduced, it is
evident that the entire quantity of gastric juice secreted
during the digestion of a single meal must be very large ;
amounting, at a very moderate estimate, to from eight to
ten pounds. Estimates, therefore, like those of Bidder and
Schmidt, which put the quantity of gastric juice secreted in
twenty-four hours by a healthy man of ordinary size at six
thousand four hundred grammes, or about fourteen pounds,2

In the latest published observations on St. Martin, by Professor F. G. Smith,
of Philadelphia, it is stated that in no case does the food remain in the stomach
more than two hours. — (Experiences sur la Digestion. — Journal de la Physiologic,
Paris 1858, tome i., p. 146.)

2 LEHMAKX, Physiological Chemistry, Philadelphia, 1855, Vol. ii., p. 520.

232 DIGESTION.

are probably not exaggerated, though they are of necessity
merely approximative.1

This enormous quantity of fluid daily secreted by the
mucous membrane of the stomach would excite surprise were
it not considered that after this fluid has performed its office
in digestion, it is immediately reabsorbed, and but a small
quantity of the secretion exists in the stomach at any one
time. During digestion, a circulation of material is going
on, in which the stomach is continually producing, out of
materials furnished by the blood, a fluid which liquefies cer-
tain elements of the food, and, as fast as this is accomplished,
is absorbed again by the blood, together with the principles
that have been thus digested.

Composition of the Gastric Juice.

The gastric juice is mixed in the stomach with more or
less mucus secreted by the lining membrane. "When drawn
by a fistula, it generally contains particles of food which have
become triturated and partially disintegrated in the mouth,
and is always mixed with a certain quantity of saliva which is
swallowed during the intervals of digestion, as well as when
the stomach is in a state of functional activity. By adopting
certain precautions, however, the fluid may be obtained
nearly free from impurities, except the admixture of saliva.
The juice taken from the stomach during the first moments
of its secretion, and separated from mucus and foreign mat-

1 In many works on physiology, the question of the quantity of gastric juice
secreted is very fully discussed. In the case of gastric fistula in a female,
already referred to (see p. 177), the quantity of fluid secreted in twenty-four hours
was estimated, from direct observations, at more than one-fourth the weight of the
body. (SCHMIDT, Ueber die Constitution des menschliclien Magcmaftes. — Annal-en
der Chemie und Pharmacie, Heidelberg, 1854, Bd. xcii., S. 43.) In this case, it
was estimated that nearly nine thousand grains were secreted in an hour, and the
calculation for the twenty-four hours was made from this quantity. It is not
shown that the fluid thus collected was normal, either in quantity or quality ; and
even if it were, it is incorrect to suppose that its production in such quantity
continues during the twenty-four hours. These, and, indeed, all other estimates
made on the same principle, are entitled to but little consideration.

COMPOSITION OF THE GASTRIC JUICE. 233

ters by filtration, is a clear fluid, of a faint yellowish or
amber tint, and possessing little or no viscidity* Its reac-
tion is always strongly acid ; and it is now a well established
fact that any fluid, secreted by the mucous membrane of the
stomach, which is either alkaline or neutral, is not the nor-
mal gastric juice.1

The specific gravity of the gastric juice in the case of St.
Martin, according to the observations of Beaumont and Sil-
liman, was one thousand and five;3 but later, Dr. F. Gr.
Smith found it in one instance, one thousand and eight, and
in another one thousand and nine.3 There is every reason
to suppose that the fluid, in the case of St. Martin, was per-
fectly normal, and from one thousand and five to one thou-
sand and nine may be taken as the range of the specific grav-
ity of the gastric juice in the human subject. There is un-
doubtedly considerable variation as regards specific gravity
in the inferior animals. In the dog, it has been usually
found by Dalton as high as one thousand and ten.4

The gastric juice is described by Beaumont as inodorous,
when taken directly from the stomach ; but it has rather
an aromatic and a not disagreeable odor when it has been
kept for some time. It is a little saltish, and its taste is sim-
ilar to " thin, mucilaginous water slightly acidulated with
muriatic acid." 5 The gastric juice from the dog has some-
thing of the odor peculiar to this animal.

It has been found by Beaumont, in the case of the human

1 As the gastric juice of the dog is the fluid generally used in experiments,
it is proper to state that its reaction is always more strongly acid than the fluid
from the human subject. It is unnecessary to discuss the opinions of physiolo-
gists anterior to the time of Beaumont, who disputed with regard to the reaction
of the solvent fluid of the stomach, as they had no means of deciding what was
the true gastric juice.

2 BEAUMONT, Observations, etc., p. 81.

3 F. G. SMITH, Experiences sur la Digestion. — Journal de la Physiologic, Paris,
1858, tome i., pp. 149, 152.

4 DALTON, On the Gastric Juice, and its Office in Digestion. — American Jour-
nal of the Medical Sciences, October, 1854, p. 315.

5 Op. cit., p. 85.

234 DIGESTION.

subject, and by others who have experimented on the gastric
juice of the lower animals, that this fluid, if kept in a well
stopped bottle, will retain its chemical and physiological
properties for an indefinite period. The only change which
it undergoes is the formation of a pellicle, consisting of a
vegetable confervoid growth, upon the surface, some of
which breaks' up and falls to the bottom of the vessel,
forming a whitish, flocculent sediment. We have now a
specimen of gastric juice which was taken from a dog with a
gastric fistula in January, 1862. It has no putrefactive odor,
and is apparently in the same condition as when it was first
drawn. In addition to this remarkable faculty of resisting
putrefaction, this process is arrested in decomposing animal
substances, both when, taken into the stomach and when ex-
posed to the action of the gastric juice out of the body.

There are on record no minute quantitative analyses of
the human gastric juice, except those by Schmidt, of the
fluid from the stomach of a woman with gastric fistula ; l and

1 For analyses by SCHMIDT of two specimens of gastric juice taken from the
stomach of this woman, see MILNE-EDWAKDS, Lepons sur la Physiologic, Paris,
1862, tome vii., p. 42.

In nine analyses of the gastric juice of the dog, when the saliva had been
previously shut off from the alimentary canal, Bidder and Schmidt found the fol-
lowing to be the mean composition (Die Verdauungssafte, Leipzig, 1852, S. 61):

Table of Solid Constituents of the Gastric Juice of the Dog.

Ferment, etc 17'127

Free hydrochloric acid - 3-050

Chloride of potassium 1-125

Chloride of sodium 2-507

Chloride of calcium 0*624

Chloride of ammonium 0'46S

Phosphate of lime 1*729

Phosphate of magnesia 0-226

Phosphate of iron 0-082

26-938

In another series of three experiments, in which the saliva was allowed to
pass into the stomach, the proportion of free acid was 2-337, and the proportion
of organic matter was somewhat increased. (Op. cit., p. 70.)

ORGANIC PRINCIPLE OF THE GASTKIC JUICE. 235

in this case there is reason to suppose that the secretion was
not normal. The analysis of the gastric juice of St. Martin
' by Berzelius was not minute. The analyses of Schmidt give
less than six parts per thousand of solid matter ; while Ber-
zelius found over twelve parts per thousand. In all the
comparatively recent analyses, there have been found a free
acid or acids ; a peculiar organic matter, generally called
pepsin ; and various inorganic salts, among which may be
mentioned as most important, the chlorides of sodium, po-
tassium, and calcium, with the phosphates of lime, mag-
nesia, and iron. Of these constituents, the salts possess little
physiological importance compared with the organic matter
and the acid principles.

Organic Principle of the Gastric Juice. — This principle,
called pepsin or gasterase, is an organic nitrogenized body,
peculiar to the gastric juice ; and, as we shall see further on,
is essential to its digestive properties. When the gastric fluid
was first obtained, even by the imperfect methods employed
anterior to the observations of Beaumont and of Blondlot, an
organic matter wras spoken of as one of its constituents. In
the rough analyses given by Leuret and Lassaigne, in 1825,
an " animal matter soluble in water " is mentioned ; 1 Tiede-
mann and Gmelin speak of " an animal matter insoluble in
alcohol, but soluble in water," which they regarded as sali-
vary matter, and another animal matter, soluble in alcohol
(osmazome) ; " and, finally, in a letter to Dr. Beaumont, Dr.
Dunglison states that in conjunction with Professor Emmet,
of the University of Virginia, he found in a specimen of gas-
tric juice taken from St. Martin " an animal matter, solu-
ble in cold water, but insoluble in hot." ! This principle

1 LEURET ET LASSAIGNE, Recherches Physiologiques et Chimiques pour servir
d I'Histoire de la Digestion, Paris, 1825, p. 113.

2 TIEDEMANN ET GMELIN, Recherches Experimentales Physiologiques et Chi-
miques sur la Digestion, Paris, 1827, premiere partie, p. 168.

3 BEAUMONT, Experiments and Observations on the Gastric Juice, and the Phys-
iology of Digestion, Plattsburg, 1833, p. 78.

236 DIGESTION.

was not mentioned by the authors just cited as essential to
the solvent action of the gastric juice ; but experiments on
artificial digestive fluids by Eberle, Schwann and Muller,
Wasmann, and others, demonstrated that acidulated infu-
sions of the mucous membrane of the stomach, possessing all
the physiological properties of the gastric juice, contained
an organic matter, first isolated by Wasmann, on which the
solvent powers of these acid fluids seemed to depend. The
experiments of Schwann and Muller upon the action of arti-
ficial digestive fluids are very interesting, and corrected the
mistake made by Eberle, who supposed that an organic sub-
stance, with the same properties as that made from the stom-
ach, could be extracted from any of the mucous membranes.1
Mialhe, who has obtained this substance in great purity by
the process recommended by Yogel, describes the following
properties as characteristic of the organic matter in artificial
gastric juice. Dried in thin slices on a plate of glass, it is in
the form of small, grayish, translucent scales, with a faint
and peculiar odor, and a feebly bitter and nauseous taste.
It is soluble in water and in a weak alcoholic mixture, but is
insoluble in absolute alcohol. A solution of it is rendered
somewhat turbid by a temperature of 212° Fahr., but it is
not coagulated, though it loses its specific properties. It is
not affected by acids, but is precipitated by tannin, creosote,
and a great number of the metallic salts.2 This substance
dissolved in water slightly acidulated possesses, in a verv
marked degree, the peculiar solvent properties of the gastric
juice ; but it has been found by Payen and Mialhe not to be
so active as the principle extracted from the gastric juice it-
self, which is described by Payen under the name of gas-
terase.3 In the abattoirs of Paris, Mialhe collected from the

1 MUELLER, Manuel de Physiologic, traduit par Jourdan, Paris, 1851, toine i.,
p. 465.

8 MIA.LHE, Chimie appliquee d la Physiologic et d la Therapeutiqne, Paris, 1856,
p. 39.

3 PA YEN, Note sur le Principe actifdu Sue Gastriquc. — Comptes Rendus, Par-
is, 1843, tome xvii., p. 654 et seq.

SOUKCE OF THE ACIDITY OF THE GASTBIC JUICE. 237

secreting stomachs of calves as they were killed, from six to
ten pints of gastric juice ; and from this he extracted the
pure pepsin by the process recommended by Payen, which
consists merely in one or two precipitations by alcohol. This
substance he found to be identical with the principle obtained
by Payen from the gastric juice of the dog. Its action upon
albuminoid matters was precisely the same as that of pepsin
extracted from artificial gastric juice, except that it was
more powerful.

Source of the Acidity of the Gastric Juice. — Reaumur
and Spallanzani recognized that the fluid from the stomach
has, at certain times, an acid reaction ; and subsequent ob-
servations have confirmed this fact, and shown that this re-
action is invariable during digestion. But although the most
distinguished and skilful chemists of the day have attempted
to ascertain the source of this acidity, from Prout, in 1823,
to Blondlot, in 1858, embracing Leuret and Lassaigne, Tiede-
mann and Gmelin, Berzelius, Chevreuil, Bidder and Schmidt,
Dumas, Lehmann, Bernard and Barreswil, with a host of
others, the question has not yet received a solution which is
generally accepted. It would be inconsistent with the plan
of this work to discuss all the opinions which have from time
to time been expressed upon this subject, or to attempt to
criticise the various processes employed by different chemists
in the analyses they have brought forward in support of their
views. The discussion will be confined to the question of
the existence of one or more of three acid principles ; viz.,
free hydrochloric acid, free lactic acid, and the acid phos-
phate of lime.

In 1823, Prout examined the fluid from the stomachs of
rabbits which had been fed a short time before death, and
demonstrated, apparently, the presence of free hydrochloric
acid. The method employed in these analyses was to estimate
in a certain portion of a watery extract of the contents of the
stomach the total amount of fixed chlorides (or muriates as

238 DIGESTION.

they were then called) ; in another portion, the total amount
of hydrochloric acid, both free and combined ; and in another
the total amount of 'free acid. By this process, the estimate
for the free acid was corrected by subtracting the estimated
proportion of fixed acid from the proportion of acid, free and
combinecl. An abundance of hydrochloric acid was also in-
dicated by Prout in the acid matters vomited in certain cases
of dyspepsia.1

The method made use of by some of those who profess to
have found free hydrochloric acid in the gastric juice has
been to subject the fluid to distillation, testing the acid fluid
which passes over, with nitrate of silver. This was the
method employed by Dunglison and Emmet ; 2 but the
experiments of Bernard and Barreswil on the gastric juice
from dogs, and the more recent observations of Dr. F. G.
Smith on the gastric juice from St. Martin, have shown that
this process is really of little value. The following observa-
tions by Bernard and Barreswil show conclusively that al-
though hydrochloric acid may be obtained from gastric juice
by distillation, it does not necessarily exist in the fluid in a
free state ; a very important consideration in a question in
which every thing depends upon the absolute accuracy of
modes of analyses :

In subjecting the gastric juice of the dog to distillation
at a low temperature, with all the necessary precautions, it
was found that the first products did not present an acid re-
action. It was at first thought that this would be ground
for the exclusion of hydrochloric acid, which is considered to
be volatile ; but it was found that in the distillation of water
which had been slightly acidulated with hydrochloric acid,
the first products were neutral, and the acid was only disen-
gaged in the fluid which passed over toward the last periods

1 PROUT, On the Nature of the Acid and Saline Matters usually -existing in the
Stomaclis of Animals ; read Dec. 11, 1823. — Philosophical Transactions, London,
1824, p. 45 et seq.

2 BEAUMONT, op. cit., p. 78.

SOURCE OF THE ACIDITY OF THE GASTRIC JUICE. 239

of the process. In again distilling the gastric juice, it was
found that the product was neutral, presenting no precipitate
with the nitrate of silver, until about four-fifths of the fluid
had passed over ; that afterward, the fluid which passed over
was distinctly acid, but did not precipitate with the salts of
silver ; and " finally, only toward the last instants, when
there only remained a few drops of gastric juice to evaporate,
the acid liquid which was produced gave a marked precipi-
tate with the salts of silver, which was not dissolved by con-
centrated nitric acid." ' It was found that the addition to
the gastric juice of a small quantity of oxalic acid produced
a marked opacity due to the formation of the insoluble oxa-
late of lime, while an equal quantity of the same reagent
produced no opacity in water containing a proportion of two
thousandths of hydrochloric acid, to which chloride of cal-
cium had been added. From this experiment, Bernard con-
cluded that the hydrochloric acid in the gastric juice exists
in the condition of a chloride, and not in a free state.

Prof. F. Gr. Smith, who had an opportunity of examining
the gastric juice from St Martin, in 1856, took the fluid from
the stomach after two ounces of dry bread had been chewed
and swallowed, and subjected it to distillation. The first
fluid which passed over was neutral, and the residue, after
the temperature had been :' somewhat raised, produced a
slight precipitate with the nitrate of silver, which was solu-
ble in ammonia. In another experiment, a mixture of lactic
acid and chloride of sodium in solution was subjected to dis-
tillation, and the product formed a slight precipitate with the
nitrate of silver. The precipitation, in this instance, was
attributed to the passage of a small quantity of chloride of
sodium with the vapors, and it is to this, also, that he attrib-
utes the opalescence of the products of distillation of the

1 BERNARD, Lemons dc Physiologic Experimentale, Paris, 1856, tome ii., p. 395 ;
and BERNARD, VILLEFRANCHE ET BARRESWIL, Sur les Phenomenes Chimiques
de la Digestion (deuxjeme memoire). — Comptes Rendus, Paris, 1844, tome xix.,
p. 1284 et seq.

240 DIGESTION.

gastric juice, when treated with the nitrate of silver.1 These
experiments are of great interest in so far as they confirm
the observations of Bernard, Villefranche, and Barreswil on
the gastric juice of the dog.

The experiments of Lehniann on this point are even more
conclusive. He found that pure gastric juice, when evapo-
rated in vacuo, develops hydrochloric acid; but he also
found that chloride of calcium is decomposed during evapo-
ration with lactic acid in vacuo, and attributes the generation
of hydrochloric acid in the gastric juice to the decomposition
with this salt, and not the chloride of sodium, as was thought
by Bernard, Yillefranche, and Barreswil.2

These observations explain perfectly the presence of
hydrochloric acid in liquids obtained by distillation, of the
gastric juice, without supposing that this acid, in a free state,
is one of its normal constituents. But this is not the only
ground on which the opinion that the hydrochloric is the
free acid of the gastric juice is based. Physiologists of the
present day who hold to this view rely chiefly . on the re-
cent examinations of the gastric juice of the dog by Bidder
and Schmidt. It remains now to see whether the observa-
tions of Schmidt, which apparently demonstrate the exist-
ence of a proportion of chlorine not to be accounted for ex-
cept under the supposition that it exists in the form of free
hydrochloric acid, are conclusive, when opposed to the facts
which are supposed to be inconsistent with the existence of
free hydrochloric acid in the gastric secretion. The method
employed by Bidder and Schmidt is, in brief, the following : s

The juice was taken from dogs that had been fasting for
from eighteen to twenty hours, the food having previously
been either animal or vegetable, the gastric juice in both
cases being identical. To prevent the admixture of saliva,

1 F. G. SMITH, Experiences sur la Digestion. — Journal de la Physiologie, Paris,
>1858, tome i., p. 149 et seq.

2 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. i., p. 93.

8 BIDDER UND SCHMIDT, Die Verdauungssafte, Leipzig, 1852, S. 44 et seq.

SOURCE OF THE ACIDITY OF THE GASTRIC JTHCE. 24:1

all the salivary ducts were tied before the fluid was taken
from the stomach.

The first step was to take about one hundred grammes of
cold gastric juice, strongly acidulated with nitric acid, and
precipitate it with nitrate of silver. The chloride of silver,
free from organic mixture, was then separated by filtration
and weighed, the total quantity of chlorine being calculated
therefrom. After having precipitated the excess of the salt
of silver in the filtered fluid by hydrochloric acid, the liquid
was calcinated in a porcelain vessel, and the total quantity
of bases estimated. Having thus obtained the proportion
of bases and the total quantity of chlorine, it is evident
that if this quantity be more than sufficient to saturate the
bases, the chlorine must exist in some other form, which
is supposed by Schmidt to be that of hydrochloric acid. It
was found, indeed, that .the quantity of chlorine was greater
than the equivalent of the bases estimated.

The second step was to determine, by saturating the acid
of the gastric juice with potassa, lime, or baryta, the propor-
tion of free acid. It was found by this process that the
quantity of free acid nearly corresponded with the excess of
chlorine over the quantity estimated as combined with bases
in the previous experiment.

In this process, the ammonia is necessarily lost during;
calcination; but in subsequent experiments, this substance
,was found to be constantly present, but in inconsiderable
quantity. It was also assumed to be experimentally demon-
strated that no organic acid, with the elements, C.H.O., ex-
isted in the gastric juice, except in infinitesimal quantity.

These experiments afford the strongest arguments in fa-
vor of the view that hydrochloric acid is the free acid of the
gastric juice ; but on the other hand, facts have been brought
forward, some of which have already been referred to,, which
show that this acid cannot here exist in a free state.

One of the most important of these facts is, that the addi-
tion of a small quantity of oxalic acid to gastric juice produces
16

242 DIGESTION.

a precipitate of the insoluble oxalate of lime, which does not
take place in the presence of free hydrochloric acid, even when
it exists in very minute quantity. ISTo one has denied that this
reaction always takes place in the gastric juice ; but, in this
fluid, is it inconsistent with the presence of a small quantity
of hydrochloric acid ? We have found that the addition of
two drops of ordinary hydrochloric acid to half a fluid ounce
of gastric juice does not prevent the precipitation of the oxa-
late of lime, which, in the single observation referred to,
was only prevented when the quantity of acid was increased
to five drops. On adding oxalic acid to fresh urine, the
precipitate of oxalate of lime was marked ; but after the
addition of two drops of ordinary hydrochloric acid, this re-
action did not take place. Taken in connection with the
fact that many of the ordinary chemical reactions are pre-
vented or modified in fluids containing organic substances,
this would lead us to inquire whether free hydrochloric acid
may not exist in small quantity in the gastric juice, and, as
an exceptional phenomenon, the reaction between the oxalic
acid and the soluble salts of lime still take place ; or whether
the acid may not unite with the organic principle, forming,
as was suggested by Schiff, chlorohydropeptic acid. In
support of this latter view, it is to be remembered that Mul-
der has formed combinations of organic principles with vari-
ous of the mineral acids, such as the sulphuric and the hy-
drochloric. In these compounds, the acid character remains,
but the ordinary reactions of the acid are lost. For exam-
ple, in a compound of sulphuric acid, called by Mulder, sul-
pho-proteic acid, the precipitations with baryta and lime do
not take place.1

1 These compounds of mineral acids with organic principles have been very
little studied. In view of the accurate researches of Bidder and Schmidt, and
the fact that many of the properties of fluids containing free hydrochloric acid
are wanting in the gastric juice, Longet, after a full and candid discussion of the
whole question, admits the possible existence of an acid compound of pepsin and
hydrochloric acid, characteristic of the gastric juice ; but he contends for the
existence, in addition, of a certain proportion of a free organic acid, which he

SOTTKCE OF THE ACIDITY OF THE GASTRIC JUICE. 243

•

With the abundant opportunities which have been pre-
sented for the chemical study of the gastric juice, not only in
the inferior animals, but in man, and in view of the numer-
ous elaborate researches into the nature of this fluid by the
most skilful physiological chemists of the day, it is a matter
of surprise that the question of the existence of free hydro-
chloric acid, or its condition as regards combination with the
organic matter, is not settled. It certainly cannot now be
regarded as settled beyond question. If, as is supposed by
Bidder and Schmidt, there be a proportion of chlorine which
cannot be accounted for by the quantity of ordinary bases in
the gastric juice, it probably does not exist as free hydro-
chloric acid, but is in some way united with organic matter.

In 1786, Macquart indicated the presence of lactic acid
in the gastric juice of the calf; attributing to free phosphoric
acid, the acidity of the gastric juice of the ox and the sheep.1
Since then there have been numerous analyses in which this
principle has been said to be found. Among those who
early adopted this view, may be mentioned Chevreul, Graves,
Leuret, and Lassaigne. After the -analyses by Prout, in
1823, and the observations of Beaumont on the fluid obtained
from St. Martin, and until the publication of the experi-
ments of Bernard, Yillefranche, and Barreswil, in 1844, the
hydrochloric was generally supposed to be the free acid of

supposes to be the lactic acid. (Traite de Physiologie, Paris, 1861, tome i., p.
203.)

1 MACQUART, Memoire sur le Sue Gastrique des Animaux Ruminants. — Me-
moires de la Sociele Royale de Medecine, Paris, 1786, p. 355 et seq. In a pound
of gastric juice from tire calf, obtained from animals just killed, Macquart found
forty-eight grains of lactic acid (p. 377). It is probable that the large quantity
of acid thus obtained was derived in part from the milk taken into the stomach
of the animal ; especially as Macquart mentions that sugar was likewise found,
which certainly is not a normal constituent of the gastric juice. At the time of
the observations of Macquart, the formation of lactic acid from sugar was not
known. In fact, it was only in 1780 that this acid was first described by Scheele;
and it was many years before its formation from sugar, muscular tissue, etc., waa
described.

244 DIGESTION.

•

the gastric juice.1 It is chiefly on the last-named observa-
tions— which have been supported by Bernard in his later
publications2 and by the confirmatory experiments of Leh-
mann and others — that those who admit the presence of free
lactic acid in quantity in the gastric juice rest their belief.

We have already referred to the experiments of Bernard,
which show that an artificial fluid containing chloride of sodi-
um and lactic acid in solution behaves, during distillation, in
every way like the natural gastric juice. These show also how
hydrochloric acid may be produced during the last period
of the distillation by decomposition of the chlorides. We have
seen that this observation was confirmed by Lehmann, who
noted the same reaction during evaporation at the ordinary
temperature, in vacuo^ though he supposed the action in
the gastric juice to be upon the chloride of calcium instead
of the chloride of sodium. Lehmann found in the acid resi-
due, free lactic acid, lactate of lime, and alkaline chlorides.
Bernard and Lehmann have brought forward other experi-
mental facts to prove that the gastric juice contains lactic acid.
If starch be boiled in a solution containing hydrochloric
acid, it soon loses its property of forming a blue compound
with iodine ; while if it be boiled with lactic acid, no such
change is observed. If starch be boiled with a solution con-
taining hydrochloric acid, to which has been added a soluble
lactate in excess, it remains unaltered ; which shows, accord-
ing to Bernard, that hydrochloric acid in a free state cannot
exist in the presence of an excess of a salt of lactic acid. By
similar experiments, the same observer assumes to prove
that the existence of hydrochloric acid is inadmissible in the
presence of a phosphate or an acetate in excess.3 Lehmann
has found that starch boiled with gastric juice retains the
property of being colored blue by iodine.4

1 Loc. cit.

2 BERNARD, Legons de Physiologic Experimentale, Paris, 1856, p. 393 et seq.

3 Op. cit., p. 398.

* LEHMANN, Physiological Chemistry, Philadelphia, 1855, p. 93.

SOURCE OF THE ACIDITY OF THE GASTKIC JUICE. 24:5

These experiments are considered by Bernard as positive
proof that the acid of the gastric juice is the lactic ; and the
fact " seems to him to be at the present day beyond contes-
tation." The facts adduced by Lehmann, however, are even
stronger. By operating upon a large quantity of gastric juice,
he has been enabled to form the lactates in such quantity
that he was enabled to subject them to ultimate analysis, and
determine positively the nature of the acid. He found that
the acid had the composition of lactic acid formed from
sugar, and not that of the acid formed from the juice of the
muscular tissue.1

In view of the facts above mentioned, and the somewhat
uncertain basis on which the supposition of the presence of
free hydrochloric acid is founded, it seems almost certain
that the principal free acid of the gastric juice is the lactic.
It is important to remember that while the experiments of
Bernard and Lehmann were made on gastric juice from the
dog, they have been confirmed, in their essential particulars,
by the recent observations of Prof. F. G. Smith on the nor-
mal gastric juice from the human subject.2

It now remains only to discuss the question of the exist-
ence in the gastric juice of the acid phosphate of lime, to
the exclusion altogether of free acids; a theory first proposed
by Blondlot in 1843, and entertained and defended by him,
as late as 1858, notwithstanding the fact that this view has
met with no favor hi the physiological world.3

1 Loc. tit.

2 F. G. SMITH, Experiences sur la Digestion. — Journal de la Physiologic, Paris,
1858, tome i., p. 144 ; and Philadelphia Medical Examiner, July and September,
1856.

s In a paper devoted entirely to the question of the acid principle of the
gastric juice (Nouvelles Recherches Chimiques sur la Nature etVOrigine du Prin-
cipe Acide gui domine dans le Sue Gastrique, Paris, 1851, p. 4), Blondlot
acknowledges that he remains almost alone in his opinion ; for, with the excep-
tion of Dumas, " who, while admitting the presence of free lactic acid, tacitly
declares that the existence of the biphosphate of lime cannot be mistaken," all
authors oppose his view. In the page referred to by Blondlot (DUMAS, Traite

24:6 DIGESTION.

To Blondlot belongs the rare merit of having been one
of the first, if not the very first, to propose and execute an
experiment by which the normal gastric juice could be ob-
tained in quantity from a living animal. In his first analy-
sis of the fluid thus obtained, he denied the existence of any
acid principles except the biphosphate of lime. This view he
holds at the present day ; and notwithstanding the elaborate
researches of the most distinguished physiological chemists,
in all of which a free acid of some kind has been recognized,
still ardently defends his original position. The question of
the existence in the gastric juice of the acid phosphate of
lime, to the exclusion of free acids, may be discussed in a
few words.

Assuming that the gastric juice contains a free acid, a
view which the arguments of Blondlot fail to disprove, the
question arises whether the biphosphate of lime may not also
exist in this fluid. On this point there can be no doubt.
All the modern analyses of the gastric juice give the phos-
phate of lime as one of its constituents ; and Blondlot justly
remarks that it is strange to see, in certain analyses, the
neutral phosphate of lime and hydrochloric or lactic acid put
down as existing together, as though the phosphoric acid
were able to retain the two equivalents of the base in the
presence of either of these two acids.1 The fact is, that basic
phosphate of lime (3CaO,PO5), a salt insoluble in pure water,
but soluble in acid solutions, is invariably decomposed in the
presence of acids as powerful as the hydrochloric or the lac-
tic. It then loses two equivalents of the base, and is trans-
formed into the acid phosphate (CaO + 2HO,PO&).

After having discussed the question of the existence of
the biphosphate in two elaborate memoirs, one published in

de Chimie, Paris, tome viii., p. 604), it is only stated that the acid reaction of the
gastric juice is not due exclusively to the biphosphate of lime, as was recently
advanced by Blondlot, and the existence of this principle is nowhere positively
admitted.

1 BLONDLOT, Nouvelles Recherches sur la Digestion. — Journal de la Physiologic^
Paris, 1858, tome i., p. 310, note.

SOURCE OF THE ACIDITY OF THE GASTRIC JUICE. 247

1843 and the other in 1851, in a third, Blondlot regards the
presence of this principle in the gastric juice as conclusively
established by the fact that it forms a precipitate of the neu-
tral phosphate of lime with pure lime-water ; the precipitate,
as he assumes, being formed by the neutralization of the acid
phosphate.1 This conclusion is undoubtedly perfectly legit-
imate ; and there can be no doubt but that the biphosphate
of lime always exists in the gastric juice, in greater or less
quantity. This principle must be put in the place of the neu-
tral phosphate, which is given by most authors, for the latter
salt cannot exist in a fluid containing free hydrochloric or lac-
tic acid, either of which acids would immediately appropriate
the excess of the base. That a free acid exists in the gastric
juice in a proportion more than sufficient to simply act upon
the neutral phosphates — which would then form lactates and
leave the biphosphate as the single acid principle — is shown
by the fact that the gastric juice will dissolve and act
upon an excess of the neutral phosphate of lime.2 This
fact in itself is sufficient to show that the gastric juice does
not depend for its acidity entirely on the biphosphate of
lime.

There can be no doubt of the constant presence of the
acid phosphate of lime in the gastric juice, at least in the
dog ; and its quantity is undoubtedly increased in this ani-
mal during the digestion of bones, by the action of the acid
fluid upon their phosphatic constituents ; but the arguments
of Blondlot against the existence of a free acid have little or
no weight. One of those on which most stress is laid is that
the gastric juice does not act upon the carbonates; which

1 Loc. cit., p. 309.

2 BERNARD, VILLEFRANCHE ET BARRESWIL, Sur les Pkenomenea Chimiques de
la Digestion (deuxieme memoire). — Comptes Rendus, Paris, 1844, tome xix., p.
1284. These authors state that the gastric juice will dissolve the neutral phos-
phate of lime, which is insoluble in the biphosphate (p. 1285); but this is not, as
they supposed, an argument against the existence of the biphosphate, for it has
long been well known that the neutral phosphate of lime is readily dissolved in
acid liquids.

248 DIGESTION.

would undoubtedly "be the case if it contained a free acid.
The simple reply to this is that there is sufficient evidence
to show that it is not the fact. Melsens, using a specimen of
fluid obtained by Blondlot from the dog and given to Du-
mas, found that seventy-three grammes of juice dissolved, in
twenty-four hours, 0*108 of a gramme of calcareous spar
(crystallized carbonate of lime). He confirmed this observa-
tion by several experiments, so that there can be no doubt
as to its accuracy.1

It is plain, therefore, that while the acid phosphate of
lime has been shown to be a constant constituent of the pure
gastric juice, contributing, in a certain degree, to its acidity,
it is not by any means to be regarded as the sole acid prin-
ciple ; the phosphate probably existing in this form by virtue
of the presence in this fluid of a free acid.

On what does the Acidity of the Gastric Juice depend ?

This is the simple question to which the foregoing discus-
sion naturally leads ; and it is one which can be answered
almost with positiveness, though it is not settled to the sat-
isfaction of all physiologists, and there are some conflicting
observations which can be harmonized only by new re-
searches.

Aside from the conditions under which acids, such as
the butyric, acetic, or the lactic, are developed from articles
of food taken into the stomach, the evidence is strongly in
favor of free lactic acid as the principle on which the gastric
juice mainly and constantly depends for its acidity. There
also exists a certain proportion of the biphosphate of lime ;
and this is the only condition in which a phosphate of lime
can exist in the presence of free lactic acid.

The observations of Bidder and Schmidt indicate, appar-
ently, a quantity of chlorine in the gastric juice not to be

1 MELSENS, Recherches sur VAcidite du Sue Gastrique, — Comptes JRendus, Paris,
1844, tome six., p. 1289 et seq.

SOUKCE OF THE ACIDITY OF THE GASTRIC JUICE. 24:9

accounted for by the proportion of bases obtained by ulti-
mate analysis. There is evidence sufficiently positive to
show that there is no hydrochloric acid in the gastric juice,
in a condition which allows the fluid to present the reactions
which are observed when this acid exists in a free state. If
there be any hydrochloric acid not in combination with me-
tallic bases, it is united with organic matter in such a way as
to prevent the manifestations of its ordinary properties, ex-
cepting that of acidity. The fact that some of the mineral
acids can be made to unite in this- way with albuminoid sub-
stances lends color to this supposition ; although further in-
vestigations are necessary to demonstrate that this takes place
in the gastric juice.

Ordinary Saline Constituents of the Gastric Juice. — It
has been experimentally demonstrated that artificial fluids,
containing the organic principles of the gastric juice and the
proper proportion of free acid, are endowed with all the di-
gestive properties of the normal secretion from the stomach ;
and that these properties are rather impaired when an excess
of its normal saline constituents is added, or when the rela-
tion of the salts to the water is disturbed by concentration.
Boudault" and Corvisart evaporated two hundred grammes
of the gastric juice of the dog to dryness, and added to the
residue fifty grammes of water. They found that the fluid
thus prepared, containing four times the normal proportion
of saline principles, did not possess by any means the ener-
gy of action on alimentary substances of the normal secre-
tion.1 These facts have led physiologists to attach little im-
portance to the ordinary saline principles found in the gas-
tric juice.

In the various analyses of the pure juice from the human
subject and the inferior animals, particularly dogs, chemists
have discovered the chlorides of sodium, calcium, potassium,

J Quoted by LOXGET, op. cit., tome i., p. 204.

250 DIGESTION.

and ammonium, and the phosphates of lime (necessarily in
the form of the biphosphate), magnesia, and a small propor-
tion of the phosphate of iron. Of these principles, the chlo-
ride of sodium has always been found to exist in greatest
abundance.

CHAPTER IX.

ACTION OF THE GASTRIC JUICE IN DIGESTION.

Constituents on which the activity of the gastric juice depends — Action of the
gastric juice upon meats — Action upon albumen, fibrin, caseine, and gelatine
— Action upon vegetable nitrogenized principles — Albuminose, or peptones —
Action of the gastric juice on fats — Action on saccharine and amylaceous prin-
ciples— Duration of stomach-digestion — Digestibility of different aliments in
the stomach — Action of the gastric juice upon the coats of the stomach —
Circumstances which influence stomach-digestion.

IN treating of the composition of the gastric juice, frequent
allusion has been made to its solvent action in digestion, and
the constituents on which this property depends. Certain
of the principles most readily attacked by this fluid are acted
upon by weak acid solutions containing no organic matter ;
but though some physiologists have been disposed to regard
the acts of solution which take place in the stomach as de-
pendent merely on the presence of a free acid, it is now well
established that the presence of a peculiar organic principle
is an indispensable condition to the performance of real di-
gestion by the gastric fluid.1 The experiments of Mialhe,2

1 BOUCHARDAT ET SANDRAS, Recherches sur la Digestion. — Annales de Chimie et
de Physique, 1842, 3me serie, tome v., p. 478 et seq. These authors attempted to
show that a feeble acid fluid was capable of dissolving fibrin and gluten, but they
failed to prove that this solution was similar to the process which takes place
in digestion. The view that the digestion of certain principles in the stomach
is due solely to the action of a free acid was also entertained by Tiedmann and
Gmelin. (Op. tit.)

3 MIALHE, Chimie appliquee d la Physiologie et d la Therapeutique, Paris, 1856,
p. 114 et seq. In these experiments, Mialhe was only carrying out the idea of
Dumas, who believed that two agents exist in the gastric juice ; viz., "the acid

252 DIGESTION.

undertaken with the view of showing that the acid simply
prepared the albuminoids by permeating them and causing
them to swell up and become gelatiniform, do not show that
solution of these principles, even after such preparation, can
be accomplished by a neutral solution of the organic princi-
ple of the gastric juice. The view thus advanced by Mialhe
was completely disproved by the observations of Longet,
who showed that when the solution was neutralized, some of
the acid fluid always remained in the substance of the nitro-
genized principle which had been subjected to its action;
and thus, when pepsin was added, the substance digested
was really permeated by a fluid containing both the organic
principle of the gastric juice and an acid. "When, on the
other hand, the fibrin, which was the nitrogenized substance
used in the experiments, was removed from the neutralized
solution, cut into slices, and washed, so as to remove. all trace
of acid, the neutral solution of pepsin had no action upon it.1

It has, indeed, been fully established that fluids contain-
ing the organic principle of the gastric juice have no diges-
tive properties unless they also possess the proper degree of
acidity ; and it is as well settled that fluids containing acids
alone have no action on albuminoids similar to that which
takes place in digestion ; and that when these principles are
dissolved by them it is simply accidental.

It is a curious fact that the presence of any one particu-
lar acid does not seem essential to the digestive properties
of the gastric juice, so long as the proper degree of acidity
is retained. In the experiments of Bernard, Villefranche,
and Barreswil, after saturating the gastric juice with neu-

wlrich softens and swells up the nitrogenized matter ; the pepsin or the chymo-
sine which determines its liquefaction by a phenomenon analogous to that of the
action of diastase on starch." (Traite de Chimie, Paris, 1846, tome vi., p. 380.)
This opinion of Dumas is based on experiments showing that fibrin is reduced to
a jelly-like consistence by the action of six parts of hydrochloric acid with ten
thousand parts of water, and is afterward completely dissolved by adding to the
mixture a few drops of rennet.
1 LONGET, op. cit., p. 214.

ACTION OF THE GASTEIC JUICE IN DIGESTION. 253

tral phosphate of lime and adding acetic, phosphoric, or
hydrochloric acid, in such quantity that it certainly existed
in a free state, the digestive properties of the fluid were re-
tained. These authors regard it as essential that the normal
acid of the gastric juice should be thus capable of being
replaced indifferently by other acids; for, they say, in
case any salt were introduced into the stomach which would
be decomposed by the lactic acid of the gastric juice, diges-
tion would be interfered with, unless the liberated acid
could take its place.1 It can readily be appreciated that
transient disturbances might occur from this cause were the
.existence of any one acid principle indispensable to the di-
gestive properties of the gastric juice ; while if only a certain
degree of acidity were required, this condition might be pro-
duced by any acid, either derived from the food or produced
by secretion.

Enough has already been said under the head of the or-
ganic principle of the gastric juice to show that the presence
of this substance is likewise a condition indispensable to
digestion.

The necessity of an acid and an organic principle in the
gastric juice can be shown by the following simple experi-
ment, which we have often made use of as a class-demon-
stration : Take three cubes of coagulated white of egg, one
of which is put into pure gastric juice, the other into gastric
juice which has been carefully neutralized, and the third
into gastric juice in which the properties of the organic prin-
ciple have been destroyed by boiling. If the three speci-
mens be kept at about the temperature of the body for a
number of hours, the albumen in the pure juice will be
found to be partially or completely reduced to a grumous
consistence, readily breaking up between the fingers, while
the other specimens are scarcely acted upon.

As far as has been ascertained by experiments in artificial
digestion, the mucus, which always exists in greater or less

1 Op. dt. — Comptes Rendus, Pari?, 1844, tome xix., p. 1289.

254: DIGESTION.

quantity in the stomach, does not seem to be important.
It is usual in these experiments to separate mucus and
extraneous matters from, gastric juice by filtration before
it is used; and the digestive properties of the fluid thus
treated are not sensibly affected when the mucus is allowed
to remain.1

In studying the physiological action of the gastric juice,
it must always be borne in mind that the general process of
digestion is accomplished by the combined, as well as the
successive action of the different fluids. The act should be
viewed in its ensemble ', rather than as a process consisting of
several successive and distinct operations, in which different
classes of principles are dissolved by distinct fluids. The
food meets with the gastric juice after having become im-
pregnated with an immense quantity of saliva ; and it passes
from the stomach to be acted upon by the intestinal fluids,
having imbibed both saliva and gastric .juice. By studying
the different digestive fluids in too exclusive a manner, many
physiologists, while professing to assign definite and distinct
properties to each, thus investing the function of digestion
with an attraction of simplicity, have necessarily ignored or
distorted facts, and assumed a completeness for the sum of
our information on this subject, which does not exist. There
could be no more serious barrier than this in the way of
farther knowledge of a function, concerning which much
remains to be learned.

"When the acts which take place in the mouth are prop-
erly performed, the following alimentary substances, commi-
nuted by the action of the teeth and thoroughly insalivated^
are taken into the stomach : muscular tissue, containing the

1 Blondlot has shown (Traite Analytique de la Digestion, Paris, 1843, p. 292),
that mucus is not acted upon by the gastric juice, even after prolonged contact at
the temperature of the body. The mucus which is secreted in the stomach is,
as far as has been ascertained, precisely like the secretion of ordinary mucous
membranes ; and it does not possess any peculiar properties, like, for example,
the viscid secretion from the intestinal mucous membrane.

ACTION OF THE GASTKIC JUICE UPON MEATS. 255

muscular substance enveloped in its sarcolemma, blood-ves-
sels, nerves, white fibrous tissue holding the muscular fibres
together, interstitial fat, and a small quantity of albumen,
fibrin, and corpuscles from the blood, all combined with a
considerable quantity of inorganic saline matters ; albumen,
sometimes unchanged, but generally in a more or less perfectly
coagulated condition ; fatty matter, sometimes in the form
of oil and sometimes enclosed in vesicles, constituting adipose
tissue 5 gelatine and animal matters in a liquid form extracted
from meats, as in soups ; caseine, in its liquid form united
with butter and salts in milk, and coagulated in connection
with various other principles in cheese ; vegetable nitrogen-
ized principles, of which gluten may be taken as the type ;
vegetable fats and oils ; saccharine principles, both from the
animal and vegetable kingdom, but chiefly from the vegetable ;
the different varieties of amylaceous principles ; and finally,
organic acids and salts, chiefly from vegetables. These prin-
ciples, particularly those from the vegetable kingdom, are
united with more or less innutritions matter, such as cellu-
lose. They are also seasoned with aromatic principles, con-
diments, etc., which are not directly used in nutrition.1

The various articles coming under the head of drinks
are taken without any considerable admixture with the sa-
liva. They embrace water, the various nutritious or stimu-
lant infusions (including alcoholic beverages), with a small
proportion of inorganic salts in solution.

All articles enumerated above are more or less modified
in the stomach; and the action of the gastric juice upon
them will now be taken up in detail.

Action of the Gastric Juice upon Meats. — There are
three ways in which the action of the gastric juice upon the
various articles of food may be studied. One is to subject them
to the action of the pure fluid taken from the stomach, as

1 Condiments and articles of this class have already been considered with,
sufficient minuteness. (See p. 100.)

256 DIGESTION.

was done by Beaumont in the human subject, and by Blond-
lot and others in experiments upon the inferior animals;
another is to make use of properly prepared acidulated infu-
sions of the mucous membrane of the stomach, which have
been shown by Schwann, Miiller, Mialhe, and others, to have
sensibly the same properties as the gastric juice, differing only
in activity ; and another is to examine from time to time the
contents of the stomach after food has been taken. By all
of these methods of study, it has been shown that the diges-
tion of meat in the stomach is far from being complete.
The parts of the muscular tissue most easily attacked are
the fibrous tissue which holds the muscular fibres together,
with the sarcolemma, or sheath of the fibres themselves. If
the gastric juice of the dog be placed in a vessel with finely
chopped lean meat, and kept in contact with it for a number
of hours at from 80° to 100° Fahr., agitating the vessel occa-
sionally, so as to subject, as far as possible, every particle of
the meat to its action, the filtered fluid will be found increased
in density, its acidity diminished in intensity, and presenting
all the evidences of having dissolved a considerable portion
of the tissue. There always, however, will remain a certain
portion which has not been dissolved. Its constitution is nev-
ertheless materially changed ; for it no longer possesses the
ordinary character of muscular tissue, but easily breaks down
between the fingers into a pultaceous mass. On subjecting
this residue to microscopic examination, it is found not to
contain any of the white inelastic fibres ; and the fibres of
muscular tissue, though presenting the well-marked and
characteristic striae, are broken into short pieces and possess
very little tenacity. It is evidently only the muscular sub-
stance which remains; the connective tissue and the sar-
colemma having been dissolved. These facts we have
repeatedly noted, and even on adding fresh juice to the
undigested matter, have been unable to dissolve it to any
considerable extent; the residue not being sensibly di-
minished in quantity, and the muscular substance always

ACTION" OF THE GA8TKIC JUICE UPON MEATS. 257

presenting its characteristic strise, on microscopic examina-
tion.

Although it is stated by many, in a general way, that the
nitrogenized alimentary principles are digested by the gas-
tric juice, a review of actual experiments will show that the
digestion of meat in the stomach is substantially such as we
have just indicated. Beaumont, in his experiments on arti-
ficial digestion, while he frequently states that the meat is
completely digested, describes the mixture, after a digestion
of eight or nine hours, as about the color of whey, and de-
positing a fine sediment of a reddish color after standing for
a few minutes.1 In no case does he distinctly state that meat
is ever completely dissolved. Pappenheim is quoted by Lon-
get as having examined animal matters, ^especially muscular
tissue, in various stages of digestion by the gastric juice, and
noted the disintegration of the tissue and division of the mus-
cular fibres into fragments, but not the solution of the true
muscular substance.2 Burdach, in his elaborate treatise on
physiology, describes the digestion of meat as consisting in the
solution of its cellular tissue, which is dissolved, first separa-
ting the muscular fibres, and finally being converted into a
pultaceous mass, more or less brown.3 The same facts, essen-
tially, have been noted by Bernard in experiments with the
gastric juice of different animals. This observer has found
that the fluid from the stomach of the rabbit or the horse is
much inferior, as regards the activity of its action upon meat,
to the gastric juice of the dog.4 He compares the disinte-
grating process which takes place in the stomach to the ac-
tion of boiling water in cooking. Dr. Dalton has found, in
the dog, that during digestion, partially disintegrated mus-
cular fibres, 'still recognizable on microscopic examination,

1 BEAUMONT, Experiments and Observations on the Gastric Juice and the Phys-
iology of Digestion, Plattsburg, 1833, p. 129.

2 LONGET, op. cit., tome i., p. 222.

3 BURDACH, Traite de Physiologic, Paris, 1841, tome ix., p. 273.

4 BERNARD, Lemons de Physiologic Experimentale, Paris, 1851, p. 414.

17

258 DIGESTION.

pass from the stomach into the small intestine, and can be
distinguished in the tube for a considerable distance.1

"Whether the gastric juice be entirely incapable of acting
upon the muscular substance or not, the above-mentioned
facts clearly show that, usually, muscular tissue is not com-
pletely digested in the stomach. The action in this organ is
to dissolve out the inter-muscular fibrous tissue and the sar-
colemma, or sheath of the muscular fibres, setting the true
muscular substance free, and breaking it up into small parti-
cles. The mass of tissue is thus reduced to th'e condition
of a thin pultaceous fluid which passes into the small intes-
tine, where the process of digestion is completed. As far as
a great part of the muscular substance is concerned, the ac-
tion in the stomach is preparatory, and not final.

The constituents of the blood (fibrin, albumen, and cor-
puscles), which may be introduced in small quantity in con-
nection with muscular tissue, are probably completely dis-
solved in the stomach.

Action upon Albumen, Fibrin, Caseine, and Gelatine. —
Dr. Beaumont thought that raw albumen, or white of egg,
became first coagulated in the stomach, and was afterward
dissolved ; but this has been disproved by numerous other
observers, who, however, have experimented chiefly on dogs.
Reference to the experiments of Beaumont will show that
the phenomena which he described as taking place in a mix-
ture of equal parts of white of egg and gastric juice, kept at
the temperature of the body for three hours, do not really
indicate coagulation. He states that " 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 in-
crease for three hours, at which time the fluid had become
of a milky appearance ; the small flocculi, or loose coagula,

1 DALTON, A Treatise on Human Physiology, Philadelphia, 1864, p. 157

ACTION OF THE GASTRIC JUICE UPON ALBUMEN. 259

had mostly disappeared, and a light-colored sediment
sided to the bottom." * If white of egg be mixed with equal
parts of pure water and be gently stirred with a glass rod,
the same small white flocculi will make their appearance,
and the mixture will become opaque and whitish. This is
due to the disengagement of shreds of the membranes in
which the clear albumen is contained ; these being invisible
in pure white of egg, from the fact that the two substances
have the same refractive power. A very different appear-
ance is presented when water containing even a small quan-
tity of nitric acid is added to the albumen. True coagula-
tion then takes place ; and the mixture becomes immediate-
ly filled with large dense clots ; or the mass may become
nearly solidified, if the acid be added in sufficient quantity.
Longet and Schiif injected a filtered watery mixture of al-
bumen into the stomach of the dog through a fistulous open-
ing, and found that no coagulation took place.2

The action of the gastric juice upon uncooked white of
egg .is to disintegrate its structure, separating, and finally
dissolving the membranous sacs in which the pure albumen
Is contained. It also acts upon the albumen itself, forming
a new fluid substance, called albuminose, or albumen-pep-
tone, which, unlike albumen, is not coagulated by heat or
acids, but is precipitated by alcohol, tannin, and many of
the metallic salts.

The digestion of raw, or imperfectly coagulated albumen,
takes place with considerable rapidity in the stomach.
Beaumont gave St. Martin the white of two eggs when the
stomach was empty, and found that it had been completely dis-
posed of in an hour and a half.3 The digestion of albumen
in this form is more rapid than when it has been completely
coagulated by heat,

Coagulated white of egg is almost, if not entirely dis-
solved by the gastric juice. If a cube of albumen in this con-

1 BEAUMONT, op. cit., p. 148. 2 LONGET, op. cit., p. 220.

3 Op. cit., p. 149.

260 DIGESTION.

dition be subjected to the action of the gastric juice at the
temperature of the body, taking care to agitate it occasion-
ally, the edges and corners gradually become rounded, and
nearly the whole mass finally breaks down and is dissolved,
having previously become softened, so that it is easily
crushed between the fingers. ^ Usually, one or two points
appear in the mass, which are acted upon with difficulty
or may resist solution entirely. It is a matter of common,
as well as scientific observation, that hard-boiled eggs
are less easily digested than when they are soft-boiled or
raw.

The products of the digestion of raw and of coagulated
albumen (albumen-peptone) are essentially the same. It is
probable that the entire process of digestion and absorption
of albumen takes place in the stomach; and if any pass
out at the pylorus, the quantity is exceedingly small.

Fibrin, as distinguished from the so-called fibrin of the
muscular tissue, or masculine, is not a very important ar-
ticle of diet. The action of the gastric juice upon it is
more rapid and complete than upon albumen. Mialhe, who
has made numerous experiments on the action of the gastric
juice upon albuminoid substances, found the coagulated and
washed fibrin of the blood readily fluidified by an acidulated
solution of pepsin.1 The well known action upon fibrin of
water slightly acidulated with hydrochloric acid has led some
physiologists to assume that the acid is the only principle in
the gastric juice necessary to the digestion of this principle ; 2
but careful observations on the comparative action of acidu-
lated water and of artificial or natural gastric juice show that

1 MIALHE, Chimie appliquee d la Physiologic et d la Therapeutique, Paris,
1856, p. 115 et seq.

2 BOITCHARDAT ET SANDRAS, Recherchcs sur la Digestion. — Annales de Chimie
et de Physique, Paris, 1842, 3me serie, tome v., p. 478 et seq. These observers
attached great importance to the acid principle of the gastric juice in digestion'.
They supposed that it was the sole principle necessary to the digestion of fibrin
and some other nitrogenized substances, though they recognized the necessity
of the organic substance in the digestion of coagulated albumen.

ACTION OP THE GASTRIC JUICE UPON CASEINE. 261

the presence of the organic principle is necessary to the di-
gestion of this, as well as other nitrogenized alimentary prin-
ciples. The action of water containing a small proportion
of acid is to render fibrin soft and transparent, frequently
giving to the entire liquid a jelly-like consistence. The sub-
stance thus produced has been likened by Mialhe to caseine,
as it is precipitable by acids and by rennet. The result of
the digestion of fibrin in the gastric juice, or in an acidulated
fluid to which pepsin has been added, is its complete solution
and transformation into a substance which is not affected by
heat, acids, or by rennet.

The substance resulting from the action of. gastric juice
upon fibrin, called by Lehmann, fibrin-peptone, presents
many points of similarity with the albumen-peptone, but
nevertheless has certain distinctive characters. Lehmann,
indeed, supposes that there are differences between the prod-
ucts of the digestion of all the various nitrogenized aliment-
ary principles, sufficiently well marked to distinguish them
from each other.1

Liquid caseine is immediately coagulated by the gastric
juice, by virtue both of the free acid and the organic matter.
Kennet, which is so largely used for the coagulation of caseine
in the manufacture of cheese, is probably nearly identical with
pepsin. Once coagulated, caseine is acted upon in the same
way as coagulated • albumen. The caseine which is taken as
an ingredient of cheese is digested in the same way. Ac-
cording to Lehmann, coagulated caseine requires a longer
time for its solution in the stomach than most other nitro-
genized substances ; and it is stated by the same author, on
the authority of Elsasser, that the caseine of human milk,
which coagulates only into a sort of jelly, is more easily di-
gested than caseine from cow's milk.2

The product of the digestion of caseine is a soluble sub-

1 LEHMANX, Physiological Chemistry, Philadelphia, 1855, rol. i., p. 451 et seq.
3 Ibid.

262 DIGESTION.

stance, not coagulable by heat or the acids, called by Leh-
inann, caseine-peptone.

Gelatine is rapidly dissolved in the gastric juice, when it
loses the characters by which it is ordinarily recognized, arid
no longer forms a jelly on cooling.1 This substance is much
more rapidly disposed of than the tissues from which it is
formed ; and the products of its digestion in the gastric juice
resemble the substances resulting from the digestion of the
albuminoids generally.

Action on Vegetable Nitrogenized Principles. — These
principles, of which gluten may be taken as the type, are
undoubtedly chiefly, if not entirely, digested in the stomach.
Raw gluten is acted upon very much in the same way as
fibrin ; and cooked gluten behaves like coagulated albumen.
Vegetable articles of food generally contain gluten in greater
or less quantity, or principles resembling it, as well as various
non-nitrogenized principles, and cellulose. The fact that these
articles are not easily attacked in any portion of the aliment-
ary canal, unless they have been well comminuted in the
mouth, is shown by the passage of grains of corn, beans, etc.,
in the faeces. When properly prepared by mastication and
insalivation, the action of the gastric juice is to disintegrate
them, dissolving out the nitrogeiiized principles, freeing the
starch and other matters so that they may be more easily
acted upon in the intestines, and leaving the hard indigest-

1 Blondlot studied the comparative action of acidulated water and gastric
juice from the dog upon gelatine. He took three vessels, each capable of hold-
ing thirty grammes, in each of which he put ten grammes of jelly obtained by
boiling one part of isinglass with twenty of water. He then filled the vessels,
one with gastric juice, and the two others with water acidulated with phosphoric
and with acetic acid. By the action of heat, the jelly was soon dissolved in each
of the three vessels. After ten hours, he found that while the specimens of gela-
tine in the acidulated water formed a jelly on cooling, so that the vessel could
be inverted without any of the substances escaping, the specimen which had been
digested in gastric juice retained its fluidity. ( Traite Analytique de la Digestion,
Paris, 1843, p. 290.)

OR PEPTONES.

ible matters, such as cellulose, to pass away in the faeces.
The nitrogenized portions of bread are probably acted upon
in the stomach in the same way and to the same extent as
albumen, fibrin, and caseine.

Albuminose^ or Peptones.

The product, or the sum of the products of the digestion
of nitrogenized alimentary principles in the stomach, was
first closely studied by Mialhe, who regarded the action of
the gastric juice on all principles of this class as resulting in
their transformation into a new substance which he called
albuminose.1 Lehmann has since investigated the principles
resulting from the action of the gastric juice on various
nitrogenized matters, and describes them under the name of
peptones.2 It has been conclusively shown that stomach-
digestion is not merely a solution of certain alimentary prin-
ciples, but that these substances undergo very marked
changes, and lose the properties by which they are generally
recognized. That the different principles resulting from this
transformation resemble each other very closely is also un-
doubted ; but there must be, as is suggested by Mialhe,
differences in the chemical composition of the products of
digestion of different principles, as well as differences, which
have lately been noted, with regard to their behavior with
reagents.

The albuminose described by Mialhe is a colorless liquid,
with a feeble odor resembling that of meat. It is not coagula-
ble by heat, acids, or by pepsin ; a property which distin-
guishes it from almost all of the nitrogenized principles of
food. It is coagulated, however, by many of the metallic salts,
by chlorine, and by a solution of tannin after it has been acidu-
lated by nitric acid.3 An interesting peculiarity of this prin-

1 MIALHE, 1} Union Medicate, Paris, septembre, 1847, and Chimie appliquee d
la Physiologie el d la Therapeutique, Paris, 1856, p. 124 et seq.
3 Op. tit., vol. i., p. 451.
3 MIALHE, op. cit., p. 125.

264: DIGESTION.

ciple is its curious modifying influence upon Trommer's test
for sugar. Prof. Dalton first noted a peculiar interference
with this test in gastric juice taken from a fistula in a dog.
He found that a drop of honey mixed with a drachm or two
of gastric juice presented, on the addition of sulphate of cop-
per and a solution of potash, the following appearance:
On adding one or two drops of the solution of copper, the
ordinary faint blue tint was produced; "but on adding the
potash, instead of this producing a greater intensity in the
blue color, as is usually the case, the solution became of a
rich purple tinge, which changed to a yellow on boiling,
without any deposit of the suboxide of copper. This pecu-
liarity was found by Dalton to be due neither to the free
acid of the gastric juice nor to the organic matter ; for it was
present, both in gastric juice which had been neutralized, and
after the organic matter had been separated by boiling and
filtration.1 A year later, the same fact was noted by Lon-
get, who ascertained that the peculiarity in the reaction was
due to the presence of albuminose, and assumed to be able
to distinguish in this way between albuminoid substances
and the principles resulting from their digestion in the stom-
ach ; ' an explanation which was afterward adopted by Dal-
ton.3 In the experiments of Dalton, the secretion of gastric
juice was generally excited by feeding the animal with
small firm pieces of meat, the exterior having been hardened
by boiling water ; and obtained in this way, the filtered fluid
from the stomach, even that which flows immediately after
the introduction of the meat, generally contains a small
quantity of albuminose.

Mialhe found, on evaporating albuminose to dryness, that

1 DALTON, On the Gastric Juice and its Office in Digestion. — American Jour-
nal of the Medical Sciences, October, 1854, p. 319.

2 LONGET, Nouvelles Recherclies relatives d I1 Action du Sue Gastrique sur lex
Matieres Albumino'idcs. — Gazette Hebdomadaire, No. 6, Paris, fevrier, 1855, tome
ii., p. 103.

3 DALTON, A Treatise on Human Physiologij, third edition, Philadelphia, 1864,
p. 143.

ALBUMINOSE, OK PEPTONES. 265

the residue consisted of a yellowish-white substance, resem-
bling desiccated white of egg. The dry residue is soluble in
water, when it regains its characteristic properties ; but it is
entirely insoluble in alcohol.

The observations of Lehmann on albuminose, or pep-
tones, were more extended. He found a great similarity
between the substances resulting from the digestion of the
various albuminoid bodies, and even those produced by the
digestion of gluten, chondrine, and gelatinous tissues. He
was unable to obtain the peptones free from mineral sub-
stances. In the condition of k greatest purity in which they
have been obtained, they have been found to be white
amorphous bodies, odorless, having a mucous taste, very
soluble in water, and insoluble in alcohol. Their watery
solutions redden litmus. They combine readily with bases,
forming neutral salts which are soluble in water.1 The
differences between the various peptones are not, as yet,
very well defined. Lehmann states that they always con-
tain the same proportion of sulphur that existed in the albu-
minoid substance from which they are formed.

According to Lehmann, the gastric juice transforms the
various nitrogenized alimentary principles into these liquid
suBstances, which are not easily coagulable, and which pre-
sent slight differences in chemical composition and gen-
eral properties, varying with the principles from which they
are formed. Those which have been most particularly de-
scribed are fibrin-peptone, albumen-peptone, and caseine-
peptone. It does not appear, however, that the differences
between the substances resulting from the digestion of the
various nitrogenized bodies are sufficiently definite to estab-
lish a rigorous distinction between them ; and until we are
better acquainted with their distinctive properties, it is best,
perhaps, to preserve the name albuminose, applying it to
the substance resulting from the action of the gastric juice
upon the albuminoids. "We are as yet too little acquainted

1 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. i., p. 451.

266 DIGESTION.

with the chemistry of organic nitrogenized bodies to be able
to follow out closely all the changes which take place during
their digestion.1

With even the imperfect knowledge which we have of
the properties of albuminose, it is evident that the object of
stomach-digestion, aside from its function in preparing cer-
tain articles for the action of the intestinal fluids, is not simply
to liquefy certain of the alimentary principles, but to change
them in such a way as to render them endosmotic and pro-
vide -against the coagulation which is so readily induced in
ordinary nitrogenized bodies. Albuminose passes through
membranes with great facility, and, as we have seen, is not
coagulable by heat or the acids.

Another, the most important and the essential change
which is exerted by the gastric juice upon the albuminoids,
is that by which they are rendered capable of assimilation
by the system after their absorption. The important fact
that pure albumen and gelatine, when injected into the
blood, are not assimilable but are rejected by the kidneys
was first demonstrated by Bernard and Barreswil. These
observers found also that albumen and gelatine which had
previously been digested in gastric juice were assimilated
in the same way as though they had penetrated by the
natural process of absorption from the alimentary canal.'
Mialhe has repeated these experiments, and arrived at the
same conclusions. He has also found that the same is true
of caseine and fibrin.3

1 Before the researches of Mialhe, little or nothing of a positive nature was
known regarding the products of stomach- digestion. The substance now called
albuminose was then indefinitely described under the names of osmazome, sali-
vary matter, gelatiniform matter, etc.

2 BERNARD ET BARRESWIL, Memoire sur le Sue Gastrique et son Role dans la
Nutrition. — Comptes Rendus, Paris, 1844, 2me serie, tome xii., p. 277.

a MIALHE, op. cit., p. 127. With regard to the experiments of Bernard and
Barreswil, it is justly remarked by Berard (Traite de Physiologic, tome ii., p. 133)
that, as the digestion of albuminoid principles takes away from them the charac-
ters by which they are ordinarily recognized, albumen could not, of course, b&

ACTION OF THE GASTRIC JTJICE ON FATS. 267

These facts, showing that something more is necessary in
stomach-digestion than mere solution, point to pepsin as
the important active principle in producing the peculiar
modifications so necessary to proper assimilation of nitro-
genized alimentary substances. The action which takes
place is one of those ordinarily termed catalytic, in which
the pepsin, acting by its mere presence, as a ferment, induces
these peculiar changes.1 They are, however, an essential,
and the most important part of the action of the gastric juice,
and the transformation into albumin ose takes place in all
nitrogenized principles which are liquefied in the stomach.
As it is impossible for two catalytic processes to take place
at the same time in any single organic substance, the more
powerful always overcoming and taking the place of the
weaker, it is evident that when nitrogenized principles in
process of putrefaction are introduced into the stomach, the
catalytic process of putrefaction must cease when the
changes which take place in digestion become established.
This explains the antiseptic properties of the gastric juice,
and the frequent innocuousness of animal substances in va-
rious stages of decomposition taken into the stomach.

Action of the Gastric Juice on Fats. — Beaumont does
not say much with regard to the changes which fatty sub-
stances undergo in the stomach, except that they " are di-
gested with great difficulty." 2 All the recent observations
on this subject show that these principles, when taken in the
condition of oil, pass out at the pylorus unchanged. Most

recognized in the urine. In a subsequent account by Bernard of experiments on
the injection of albumen into the circulation (Liquides de V Organisrne, Paris,
1859, tome ii., p. 459), there is no mention of the effects of injecting albumen
dissolved in the gastric juice, though the first experiments upon the injection of
pure albumen are confirmed. The facts are nevertheless interesting and instruc-
tive, as showing the want of assimilation of undigested nitrogenized principles
mixed with the blood.

1 For a definition of the process of catalysis, see vol. i., p. 74.

2 Op. cit., p. 45.

268 DIGESTION.

of the fatty constituents of the food are liquefied at the tem-
perature of the body ; and when taken in the form of adipose
tissue, the little vesicles in which the oleaginous matter is
contained are dissolved, the fat is set free and melted, and
floats in the form of great drops of oil on the alimentary
mass. The action of the stomach, then, seems to be to pre-
pare the fats, chiefly by dissolving the adipose vesicles, for
the complete digestion which takes place in the small intes-
tine.

Action on Saccharine and Amylaceous Principles. — The
varieties of sugar of which glucose is the type undergo little,
if any, change in digestion, and are probably for the most
part directly absorbed by the mucous membrane of the
stomach. This is not the case, however, with the varieties
of sugar classed with cane-sugar. The experiments of Ber-
nard and Barreswil1 have shown that cane-sugar injected
into the veins of a living animal is not assimilated by the
system, but is immediately rejected by the kidneys. "When,
however, it has been changed into glucose by the action of a
dilute acid, or by digestion in the gastric juice, it no longer
behaves as a foreign substance, and does not appear in the
urine.

This leads to a consideration of the changes which cane-
sugar undergoes in the stomach. Experiments have shown
that this variety of sugar, after being digested for several hours
in the gastric juice, is slowly converted into glucose. This
action, according to the recent observations of Longet and
Schiff, does not depend upon any constituent of the gastric
juice except the free acid ; and they found that an exceedingly
dilute mixture of hydrochloric acid had an equally marked
effect.2 Dalton founcl that, in the dog, the ingestioii of cane-
sugar induced, almost invariably, an immediate reflux of
intestinal fluids, including bile, by which it was promptly

1 Loc. cit.

2 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 221.

ACTION ON SACCHARINE AND AMYLACEOUS PRINCIPLES., 269

converted into glucose.1 This, however, he found to be only
temporary ; and in experiments in which half an ounce of
loaf-sugar was given to the animal after a twelve hours' fast,
unaltered cane-sugar remained in the stomach for from two
and a half to three hours.

Experiments in artificial digestion have shown that cane-
sugar is transformed into glucose by the gastric juice very
slowly, the action of this fluid in no way differing from that
of very dilute acids. In the natural process of digestion, this
action may take place to a certain extent ; but it is not shown
to be constant or important, and we must look to intestinal
digestion for rapid and effective transformation of cane-sugar.

The action of gastric juice, unmixed with saliva, upon
starch is entirely negative, as far as any transformation into
sugar is concerned. When the starch is enclosed in vegeta-
ble cells, it is set free by the action of the gastric juice/ upon
the nitrogenized parts. It has been found by Bernard that
raw starch, in the form of granules, becomes hydrated in
the stomach; and he attributes this action to the elevated
temperature and to the acidity of the contents of the organ.2
This is not the form, however, in which starch is generally
taken by the human subject ; but when it is so taken, the
stomach evidently assists in preparing it for the more com-
plete processes of digestion which are to take place in the
small intestine.

Cooked or hydrated starch, the form in which it exists in
bread, farinaceous preparations generally, and ordinary vege-
tables, is not affected by the pure gastric juice, and passes out
at the pylorus unchanged. It must be remembered, however,
that the gastric juice does not prevent a continuance of the
action induced by the saliva ; and experiments have shown
that gastric juice taken from the stomach, when it contains a
notable quantity of saliva, has, to a certain extent, the power

1 DALTON, On the G-asiric Juice and its Office in Diyestiam. — American Jour-
fial of the Medical Sciences, October, 1854, p. 319.

'J BERNARD, Leco-m de Physiologie Experimentale, Paris, 1856, p. 401.

270 . DIGESTION.

of transforming starch into sugar.1 It has already been re-
marked that, with regard to this question, experiments on
dogs, as these animals do not naturally take starch as food,
do not correspond with observations on the human subject.

The changes which vegetable acids and salts, the various
inorganic constituents of food, and the liquids which come
under the head of drinks undergo in the stomach are very
slight. Most of these principles can hardly be said to be
digested ; for they are either liquid or in solution in water,
and are capable of direct absorption and assimilation. "With
regard to most of the inorganic salts, they either exist in
small quantity in the ordinary water taken as drink, or are
united with organic nitrogenized principles. In the latter
case, they become intimately combined with the organic
principles resulting from stomach-digestion. We have al-
ready seen that the various peptones have been found to
contain the same inorganic constituents which existed in the
nitrogenized principles from which they were formed.

Some discussion has arisen with regard to the action of the
fluids of the stomach upon the phosphate and the carbonate
of lime ; salts which are considered nearly, if not entirely,
insoluble. The action upon these principles is interesting,
as they are essential constituents of the osseous tissues. Ob-
servations in both natural and artificial digestion have shown
that the calcareous constituents of bone are, to a certain ex-
tent, dissolved in the gastric juice. The experiments of Chos-
sat upon animals deprived of these principles in the food
demonstrated that they are absolutely necessary to proper nu-
trition,2 and therefore must be dissolved somewhere in the ali-
mentary canal • and the well-known fact that the phosphate
of lime is soluble in acid fluids, when it is converted into the
biphosphate, would point at once to the gastric juice as the
agent for its digestion. In fact, it has been clearly shown
that bones are digested to a considerable extent in the stom-

1 See page 177. 2 See page 65.

DUEATION OF STOMACH-DIGESTION. ' 271

ach, though, the greater part passes through the alimentary
canal and is discharged unchanged in the faeces. Beaumont
has shown this to be true in the human subject by experi-
ments which he performed, out of the body, with gastric juice
taken from St. Martin.1 In these observations, after a cer-
tain portion of the bone had been dissolved, the action was
increased by the addition of fresh gastric juice. In the
natural process of digestion, the solution of the calcareous
elements of bone is more rapid than in artificial digestion,
from the fact that the juice is being continually absorbed
and secreted anew by the mucous membrane of the stomach.

Duration of Stomach-Digestion.

'Now that the relative importance of the stomach and
the small intestines in digestion is more fully understood,
less interest is attached to the length of time required for
the action of the gastric juice upon different articles of food
than formerly, when the stomach was regarded as the prin-
cipal, if not the sole digestive organ. It was thought at
one time that the food was converted in the stomach into a
pultaceous mass called chyme,2 which passed into the intes-
tine, where the assimilable portion (the chyle) was separated
and absorbed by the lacteals. Eeaumont, in preparing the
elaborate table which has been so much quoted, conceived
that the simple action of the gastric juice represented the
chief part of the digestive process ; and that it was possible,
from experiments with this fluid, to ascertain the digesti-
bility of different articles. From this point of view he re-
gards fatty substances, which are now known to be digested

1 BEAUMONT, op. cit., p. 200.

2 The word chyme, like many words used by the earlier physiologists, under
the supposition that they represented definite principles, has for some time been
practically discarded, on account of its indefinite signification. It is particularly
inexact, as the mass resulting from the action of the gastric juice upon the varied
articles used as food is composed of many undigested substances, as well as dis-
tinct substances resulting from the digestion of different alimentary principles.

272 DIGESTION.

exclusively in the small intestines, as requiring a very long
time for their digestion.

Understanding, as we do, that comparatively few articles,
and these belonging exclusively to the class of organic nitro-
genized principles, are completely dissolved in the stomach,
it is evident that the length of time during which food re-
mains in this organ, or the time occupied in the solution of
food by gastric juice, out of the body, does not represent the
absolute digestibility of different articles. It is, nevertheless,
an interesting and important question to ascertain, as nearly
as possible, the duration of stomach-digestion.

There has certainly never been presented so favorable an
opportunity for determining the duration of stomach-diges-
tion as in the case of St. Martin. From a very great num-
ber of observations made on digestion in the stomach itself,
Beaumont came to the conclusion that " the time ordinarily
required for the disposal of a moderate meal of the fibrous
parts of meat, with bread, etc., is three to three and a half
hours." 1 The observations of Prof. F. G. Smith, made upon
St. Martin, many years later, give two hours as the longest
time that aliments remained in the stomach.2 In a remark-
able case of intestinal fistula, reported by Prof. Busch, of
Bonn, it was noted that food began to pass out of the stom-
ach into the intestines fifteen minutes after its ingestion,
and continued to pass for three or four hours, until the
stomach was emptied.3

Undoubtedly the duration of stomach-digestion varies in
different individuals, and is greatly dependent upon the
kind and quantity of food taken, conditions of the nervous
system, exercise, etc. As a mere approximation, the average

1 Op. eit.t p. 275.

2 F. G. SMITH, Experiences sur la Digestion. — Journal de la Physiologic,
Paris, 1858, tome i., p. 146, and Philadelphia Medical JHzaminer, July and Sep-
tember, 1856.

3 BUSCH, Bietrag zur Pliysiologic der Verdauungsorganc. — VIRCHOW'S Archiv,
Berlin, Bd. xiv., S. 140 et scq., and American Journal of the Medical Sciences,
July, I860, p. 219.

DURATION OF STOMACH-DIGESTION. 273

time that food remains in the stomach after an ordinary meal
may be stated to be from two to four hours.

Digestibility of Different Aliments in the Stomach. — We
are indebted to Beaumont for nearly all that is positively
known regarding the facility with which different articles
are disposed of in the stomach. While it is fully understood
that most of the substances experimented upon by him are
not completely digested by the gastric juice, and although
he was often wrong in assuming that articles of food were
digested wrhen they had not become completely liquefied and
consequently endosmotic, the table which he prepared with
so much care was the result of such conscientious and ex-
tended research, that it must always be recognized as of great
value. Nearly all of the results given in the table are de-
rived loom experiments frequently repeated, and " performed
under the naturally healthy condition of the stomach and or-
dinary exercise." They show the mean time employed in the
digestion, in the stomach, of most of the ordinary articles of
food, in the person of a healthy young man of good digestive
powers. Of course it must be understood that there are im-
portant peculiarities in different individuals, which could not
be considered. As many of the alimentary substances exper-
imented upon are but slightly acted on by the gastric juice,
it has been thought proper, in making the selections from the
table, to discard all articles which are mainly digested in
the small intestine.

With these modifications, therefore, the following table
may be taken as representing the comparative rapidity with
which most of the ordinary nitrogenized articles are acted
upon in the stomach; they being either completely dis-
solved, and probably directly absorbed by its mucous mem-
brane or prepared for the action of the intestinal fluids, pass-
ing gradually out at the pylorus. It must be remembered,
however, that slow digestion does not always indicate that the
process is difficult, and the action of the gastric fluids upon
18

274

DIGESTION.

many articles which apparently give no trouble in digestion
is by no means rapid :

Table showing the Digestibility of various Alimentary Substances in the

Stomach.1

Articles of Diet.

Mode of
Preparation.

11

Articles of Diet.

Mode of
Preparation.

§ «

!§§

Milk.

Boiled
Eaw
do.
"Whipped
Eoasted
Soft-boiled
Ha'd-boiled
Fried
Baked
Boiled
do.
Fried
Broiled
Fried
do,
Boiled
Kaw
Eoasted
Stewed
Broiled
Eoasted
Broiled
Eoasted
Broiled
Boasted
Boiled
do.
Fried
Broiled
Boiled
Eoasted
Broiled
Fried
Broiled
Eoasted
Eaw
Stewed
Broiled
Fried
Boiled
Eoasted
Boiled
Eoasted
do.

2'00
2-15
2-00
1-30
215
3-00
3-30
3-30
2-45
2-GO
1-30
1-30
3-00
3-30
3-30
4-00
2-55
3-15
3-30
1-35
2-30
2-30
3-00
3-00
3-30
3-10
3-36
4-00
3-00
3-00
3-15
4-00
4-30
3-15
5-15
3-00
3-00
3-15
•1-Ti

Chicken, full grown
Fowls, domestic

Fricasseed
Boiled
Eoasted
do.
do.
Boiled
do.
do.
do.
do.

do.

do.
do.
do.
do.
do.
Broiled
Boiled
Fried
Boiled
do.
Warmed
Broiled
Boiled
Eaw
Boiled
do.
do.
Eoasted
Baked
Boiled
Eaw
do.
Boiled
do.
do.
do.
Baked
do.
Eaw
do.
do.

2-45
4-00
4-00
4-00
4-30
1-30
3-00
300
3-30
3-30

4-00

4-15
1-00
1-00
1-45
2-40
2-00
3-00
4-00
4-15
5-30
2-30
3-20
2-30
3-30
3-45
2-30
2-30
2-30
2-30
3-30
2-30
2-00
4-30
3-13
3-30
3-45
3-15
3-30
1-30
2-00
2-50

do

Ear^s fresh

do. do

df> do •" . :

Ducks, domesticated
do. wild

do. do ,

do. bean

do do. . ....

do. chicken

Custard

do. mutton

Trout, salmon, fresh

do. beef, vegetables, and )
bread J

do. do. do

Bass, striped, do
Flounder do . .

do. marrow-bones
Pigs' feet, soused

Catfish do

Tripe do.

Salmon salted

Brains, animal . ,
Spinal marrow, animal
Liver, beeves', fresh
Apeneurosis

Oysters, fresh

do. do

do do

Venison steak

Heart, animal

Cartilage

Tendon

Beef, fresh, lean, rare
Beef-steak

Hash, meat, and vegetables.
Sausage fresh. ....

Beef, fresh, lean, dry
do. with mustard, etc
do. with salt only
do

Gelatine

Cheese, old, strong

Green corn and beans
Beans pod

Mutton, fresh

Parsnips

Potatoes Irish

Veal, fresh

do. do

do. do ....

Cabbage head

Pork steak

do. do. with vinegar.

do. fat and lean
do. recently salted
do. do
do. do

Carrot, orange

Turnips, flat

Beets ... .

do. do.

4-30
2-18
2-25
2-30
2-30

do. wheat, fresh
Apples, sweet, mellow
do. sour, do
do. do. hard

Turkey, wild

do. domesticated
do. do

Goose, wild

Most of the facts recorded in the above table are in ac-
cordance with the popular ideas regarding the digestibility
of various articles, based on general experience. With these

1 In the original table given by Beaumont (op. cit., p. 269 et seq.\ there is
also given the mean time of digestion artificially, in vials, on a bath. This has
been omitted, as it often bears little relation to the time occupied in the diges-
tion of the same principles in the stomach, and the results are of necessity quite
inaccurate.

ACTION OF THE GASTRIC JUICE UPON THE STOMACH. 275

as a guide, the following may be taken as a summary of what
is known regarding the facility with which different articles
are disposed of in the stomach :

Milk is one of the articles digested in the stomach with
greatest ease. Its highly nutritive properties and the varie-
ty of principles which it contains make it extremely valuable
as an article of diet, particularly when the digestive powers
are impaired, and when it is important to supply the system
with considerable nutriment. Eggs are likewise highly nu-
tritious and are easily digested. Raw and soft-boiled eggs
are more easily digested than hard-boiled. 'Whipped eggs
are apparently disposed of with great facility. As a rule,
the flesh of fish is more easily digested than that of the
warm-Wooded animals. Oysters, especially when raw, are
quite easy of digestion. The flesh of mammals seems to be
more easily digested than the flesh of birds. Of the different
kinds of meat, venison, lamb, beef, and mutton are easily
digested, while veal and fat roast-pork are digested with
difficulty. Soups are generally very easily digested. The
animal substances which were found to be digested most
rapidly, however, were tripe, pigs' feet, and brains. Vege-
table articles are represented in the table as being digested
in about the same time as ordinary animal food ; but a great
part of the digestion of these substances takes place in the
small intestine. Bread is digested in about the time required
for the digestion of the ordinary meats.

Action of the Gastric Juice upon the Coats of the Stomach.

Early in the physiological history of digestion, it was
asked of those who adopted the view that the stomach se-
creted a fluid capable of dissolving many of the articles of
food, why, if such a powerfully solvent fluid be thus secreted,
are not the coats of the stomach dissolved and digested dur-
ing life ? This question was difficult to answer, even after
the existence of a solvent gastric juice had been fully demon-
strated. That the coats of the living stomach enjoy an im-

276 DIGESTION.

munity from the action of their own secretion during life is
sufficiently evident ; at the same time that it is apparent that
tissues like the stomach, and even the stomach of animals bear-
ing a close physiological resemblance to the human subject,
as, for example, tripe, are easily disposed of when used as food.

Since the observations of Hunter, in 1772, in which it
was shown that the stomach could be digested after death
in persons killed suddenly when the organ contained an
abundance of gastric juice, the cause of the immunity
of the stomach from digestion during life has been much
discussed. At. the time of Hunter's observations, it was
still a question among physiologists concerning the exist-
ence of a solvent fluid in the stomach ; and the fact noted
by him, that there were few dead bodies in which the great
pouch was not in some degree digested, while in several sub-
jects, killed suddenly while in good health and full diges-
tion, parts of the cardiac portion, and sometimes even por-
tions of the diaphragm were entirely dissolved, was a con-
clusive proof of the active solvent properties of the gastric
juice.1 The facts thus observed by Hunter, which belong
more to pathology than to physiology, were confirmed by
numerous physiologists ; and it only remained to demonstrate
the reason why solution of the coats of the stomach never
took place during life.2

The explanation offered by Hunter himself has not been
by all regarded as entirely satisfactory. It was assumed by

1 JOHN HUNTER, Observations on Certain Parts of the Animal (Economy,
second edition, London, 1792, p. 226, and American edition of Works, Philadel-
phia, 1840, vol. ii., p. 144. The original paper was read before the Royal Soci-
ety, June 18, 1772, and was printed in the Philosophical Transactions, vol. Ixii.

2 It has been found that when the human subject or one of the inferior ani-
mals is killed while in full digestion, the stomach will be digested and generally
perforated after death, the action taking place in the most dependent portion.
In order to secure this effect, it is only necessary to maintain the natural temper-
ature of the body ; this being a condition indispensable to the action of the
gastric juice, under any circumstances. We have already alluded (p. 230) to the
researches of Mr. T. W. King on this subject, in connection with the function of
different parts of the mucous membrane of the stomach.

ACTION OF THE GASTKIC JUICE UPON THE STOMACH. 277"

him that "animals, or parts of animals, possessed of the
living principle, when taken into the stomach, are not in the
least affected by the powers of that viscus, so long as the
animal principle remains." 1 It was also assumed that, by
virtue of this principle, many animals are capable of inhab-
iting the stomach, living and even breeding there. It is
undoubtedly true that a living, highly organized part, abun-
dantly supplied with blood-vessels, the process of destructive
assimilation and nutrition taking place in its substance with
great activity, is protected from the action of a fluid like the
gastric juice by the very conditions of its existence ; but it is
desirable, if possible, to define these protecting conditions
a little more closely. It is important, moreover, to know
whether it is literally true that animals may maintain an
independent existence in the living stomach, as was sup-
posed by Hunter. A recent writer on this subject states that
there are no examples of this to be found.2 The parasites
which infest the stomachs of some of the inferior animals,
as the horse or sheep, are firmly attached to, and, indeed,
partly buried in the mucous membrane. In investigating
the accuracy of a popular belief that lizards and various
other animals of that class frequently exist for a long time in
the human stomach, Dr. Dalton has lately shown that the
ordinary garden-slug and lizards, introduced living into the
stomach of the dog, are soon killed and are easily digested.3
An interesting experiment by Bernard has shown most con-
clusively that the nutritive processes, as they take place in
cold-blooded animals, do not enable the tissues to resist the
action of the gastric juice. He introduced through a fistulous
opening into the stomach of a dog the posterior extremities

1 HUNTER, Observations on Certain Parts of the Animal (Economy, London,
1792, p. 228.

2 PAYT, On the Immunity enjoyed by the Stomach from being digested by its
own Secretion during Life. — Philosophical Transactions, London, 1863, p. 169.

3 DALTON, Experimental Investigations to determine whether the Garden-Slug
can live in the Human Stomach. — American Journal of the Medical Sciences,
April, 1865, p. 334 et seq.

278 DIGESTION.

of a living frog, and the parts were sensibly acted upon by
the gastric juice, even while the animal was alive and active.1
A still more striking experiment was made by Dr. F. "W. Pavy,
who introduced through a fistulous opening into the stom-
ach of a dog in full digestion, one of the ears of a rabbit,
taking care to avoid mechanical injury, and obstructing the
circulation in the part as little as possible. At the end of
two hours, several large spots of erosion were observed upon
the ear ; and at the end of four and a half hours, rather more
than half an inch of the tip had been removed, " a small
fragment only being left attached by a narrow shred to the
remainder of the ear." 2

Bernard denies the protective influence of the "living
principle," as advanced by Hunter, and attributes the im-
munity of the stomach from digestion during life to the pres-
ence of a coating of mucus and epithelium, the latter being
continually dissolved by the gastric juice, but renewed as fast
as it is destroyed. According to this supposition, as soon as
life ceases, the epithelium being no longer renewed, the coats
of the stomach are attacked, if any gastric juice exist in its
cavity. The finger, when introduced into the living stomach
through a fistula, is not acted upon, because its epidermic
covering is not capable of being dissolved by the gastric juice ;
and the legs of the living frog are digested because the epi-
thelium is not readily restored after it is removed.3 This
explanation is unsatisfactory, for several reasons. In the first
place, it is simply a gratuitous supposition that the epithe-
lium of the stomach is constantly destroyed by the gastric
juice, and is as constantly reproduced. Again, in cases of ul-
ceration of the stomach, or other structural diseases in which
portions of the mucous membrane are deprived of epithelium,
the parts thus denuded are not acted upon by the gastric juice
during life ; and furthermore, Pavy has shown by experi-

1 BERNARD, Lemons de Physiologie Experimentale, Paris, 1856, p. 408.

PAVY, op. cit., p. 162.
8 BERNARD, op. cit., p. 404 ft seq.

ACTION OF THE GASTBIC JUICE UPON THE STOMACH. 279

ment that the mucous membrane may be dissected from a
portion of the stomach of a living animal, and the organ re-
turned to its place, and yet secretion of gastric juice and di-
gestion of food take place as usual, without the denuded
portion being acted upon.1

An explanation recently offered by Pavy is exceedingly
ingenious; and the experiments by which it is supported
demonstrate one of the conditions of highly organized living
parts which is inconsistent with the digestive action of the
gastric juice. It is well known that acidity is a condition
indispensable to the action of the gastric juice upon any prin-
ciple or tissue ; and so long as the mucous membrane lining
the stomach is abundantly supplied with a constantly chan-
ging current of blood, which is distinctly alkaline in its
reaction, it is impossible for the gastric juice to have any
effect upon it. The immense vascularity of the lining mem-
brane of the stomach, particularly during digestion, is in
itself almost a sufficient argument in favor of this explana-
tion. A tissue thus permeated writh an alkaline fluid, which
can never be neutralized during life, because it is constantly
changing, cannot be digested by the gastric juice. It is difficult
to support this view with experiments which are not open to
objection • and, undoubtedly, the strongest arguments in favor
of it lie in the known conditions necessary to digestion in the
stomach. In the case of the legs of the frog and the ear of
the rabbit, which were digested in the stomach of the dog
while the circulation in the parts was not interrupted, the
quantity of blood, in the first instance, is so small, and the
circulation so languid, that it could readily be neutralized ;
and ' the vascularity of the ear, in the second instance, is so
slight, that it can easily be conceived to be inadequate to
the protection of the tissues. Pavy has shown that the stom-
ach is digested during life in rabbits after the application of
ligatures at the cardiac and pyloric extremities, the supply
of blood being further cut off by ligatures applied to the
1 Op. dt., p. 163.

280 DIGESTION.

vessels passing to this organ. He lias likewise shown that
when the circulation is arrested during life in a portion of
the stomach by drawing it up and applying a ligature, the por-
tion thus constricted will be acted upon by the gastric juice.1
It must be remembered, however, that in both these experi-
ments, the inevitable result of the operation must be to dimin-
ish or arrest the nutritive processes, and thus produce substan-
tially the same condition which obtains after death. It is not
apparent, indeed, how any operation can be performed on a
living animal by which the circulation of the blood in the
walls of the stomach, or any part of the organ, will be inter-
rupted, without arresting the nutritive process in' the part ;
for these depend entirely upon a proper and constant supply
of the circulating fluid. Experiments have already sufficiently
well demonstrated the influence of different degrees of acidity
upon the digestive activity of the gastric juice. It is evi-
dent that after death, when the circulation is arrested, if any
considerable quantity of gastric juice should be present in
the stomach, the alkalinity of the small quantity of blood
which remains in the vessels is neutralized, and offers no ob-
stacle to the solvent action of the fluid, provided the proper
temperature be maintained.

In endeavoring to give a satisfactory answer to the ques-
tion why the stomach is not acted upon by its own secretion
during life, it is impossible to ignore a similar inquiry which
presents itself with regard to the small intestine and the
secretions which are poured into its cavity. The intestinal
secretions are undoubtedly capable of digesting, to a certain
extent, animal tissues, although the process is much more
active when these tissues have first undergone preparation in
the stomach. The alkaline reaction of the blood cannot be
regarded as the condition protecting the coats of the intes-
tines from digestion during life, for the digestive fluids in
this portion of the alimentary canal are themselves alkaline.
Is there, then, any assignable reason, aside from the alka-

1 Op. dt.

ACTION OF THE GASTRIC JUICE UPON THE STOMACH. 281

linity of the blood, why animal tissues are digested in the
alimentary canal, while the coats of the canal itself are pro-
tected ? Taking into consideration all the facts relating to
this subject, the following seem to be the most rational con-
clusions :

Although, during life, the secretions discharged into the
alimentary canal will digest the various articles of food with-
out attacking the canal itself, after death, the accumulation
in the stomach is frequently sufficient to digest the coats of
the organ, causing perforation and escape of its contents,
and acting sometimes upon contiguous parts. The accu-
mulation in the jejunum, where intestinal digestion is most
active, is never considerable ; for digestion is here complete
and rapid, and absorption follows immediately. It is impos-
sible to say whether, if the digestive fluids should remain in
quantity in this part after death, post mortem digestion of
the intestines would or would not take place.

In the living stomach, the circulation of a great quantity
of an alkaline fluid is an effectual barrier to the solution of
its tissues by the gastric juice ; for acidity is an indispensable
condition to the action of this fluid upon any substance. This
condition of the tissues would not, however, protect the walls
of the small intestine from the action of the alkaline fluids
poured into its cavity.

Inasmuch as digestion involves a catalytic transformation
of alimentary principles into new substances with distinctly
modified properties, it necessarily abolishes, for the time,
all other catalytic processes. For this reason the cata-
lytic changes incident to putrefaction are arrested by the
action of the gastric juice, the more powerful process of
transformation into albuminose, or peptones, taking its place.
It is impossible that the digestive fluids should act upon any
living part in which the catalytic changes incident to nutri-
tion are so actively in operation as in the mucous membrane
lining the alimentary canal ; for these involve a constant sup-
ply of new material, with removal of effete matter, which

282 DIGESTION.

takes place with much more rapidity than is consistent with
the gradual permeating and solvent action of any of the
digestive fluids. These fluids could not long remain in con
tact with the vascular tissues, but would be carried away in
the torrent of the circulation. The digestion of parts of a
living cold-blooded animal, in which the processes of nutri-
tion are very slow, or slightly vascular parts of a warm-
blooded animal, is not inconsistent with this supposition.1

Circumstances which influence Stomach-Digestion.

The various conditions which influence stomach-diges-
tion, except those which relate exclusively to the character
or the quantity of food, operate mainly by influencing the
quantity and quality of the gastric juice. It is seldom, if
ever, that temperature has any influence ; for the tempera-
ture of the stomach in health does not present variations
sufficient to have any marked effect on digestion. Ex-
periments in artificial digestion have shown that aliment-
ary substances are most vigorously acted upon when main-
tained in contact with gastric juice at or near 100° Fahr.

As a rule, gentle exercise, conjoined with repose or
agreeable and tranquil occupation of the mind, is more
favorable to digestion than absolute rest. Yiolent exercise
or severe mental or physical exertion is always undesirable
immediately after the ingestion of a large quantity of food,
and, as a matter of common experience, has been found to
retard digestion. These facts have also been experiment-
ally demonstrated by Beaumont in the case of St. Martin.2
Sleep, if light and taken in the sitting posture, seems almost
necessary to easy digestion in many persons ; but it should
be continued for only a few minutes. A prolonged and deep

1 If gastric juice be injected under the skin of a living animal, as was done
by Bernard (op. cit., p. 407), solution of the areolar tissue, which is non-vascular,
and in which the nutritive processes possess very little activity, takes place, and
the more vascular and highly organized parts are not attacked.

2 Op. tit., p. 94.

CIRCUMSTANCES WHICH INFLUENCE STOMACH-DIGESTION. 283

sleep immediately after a full meal is almost always inju-
rious, and extraordinary heaviness at that time is generally
an indication that too much food has been taken.

The effects of sudden and considerable loss of blood upon
stomach-digestion are very marked. After a full meal, tho
whole alimentary tract is deeply congested, and this condition
is undoubtedly necessary to the secretion, in proper quantity,
of the various digestive fluids. When the entire quantity of
blood in the economy is greatly diminished from any cause,
there is a difficulty in supplying the amount of gastric juice
necessary for a very full meal, and disorders of digestion are
apt to occur, especially if a large quantity of food has been
taken. This is also true in inanition, when the quantity of
blood is greatly diminished. In this condition, although the
system constantly craves nourishment and the appetite is
frequently enormous, food should be taken in small quanti-
ties at a time.

As a rule, children and young persons digest food which
is adapted to them more easily and in larger relative quantity
than those in adult life or in old age ; but ordinarily, in old
age, the digestive processes are carried on with more vigor
and regularity than the other vegetative functions, such as
general assimilation, circulation, or respiration.

Influence of the Nervous System on the Stomach. — It is
well known that mental emotions frequently have a marked
influence on digestion ; and this, of course, can take place
only through the nervous system. Of the two nerves which
are distributed to the stomach, the pneumogastric has been
the more carefully studied, experiments upon the sympathetic
being difficult and unsatisfactory. Though the complete
history of the influence of the pneumogastric nerves upon
digestion belongs to the section on the nervous system, it
will be interesting in this connection to consider briefly some
of the facts which have been ascertained with regard to the
influence which these nerves exert upon the stomach.

284: DIGESTION.

It Will not be necessary to discuss the opinions of the
earlier experimenters upon the influence of section of the
pneumogastric nerves in the neck on stomach-digestion ; as
their experiments were made in ignorance of the fact that
division of these nerves paralyzes the oesophagus, and ren-
ders the deglutition of most of the articles of food impossible.
After section of the nerves in the neck, acts of deglutition are
apparently performed, but the food collects in and distends
the paralyzed oesophagus, and does not pass to the stomach.1
It is not surprising, therefore, that the first experiments upon
the influence of the pneumogastrics on digestion should have
been contradictory, some contending that section of the nerves
arrested stomach-digestion, while others maintained that the
nerves had little or no influence upon the stomach. It is
evident that without an appreciation of the effects of section
of the pneumogastrics upon deglutition, observations on the
influence of their section upon stomach-digestion would be
of little value.

The recent experiments of Longet seem to show that
while section of the pneumogastrics in the neck undoubtedly
diminishes the secretion of gastric juice, the production of
this fluid is not entirely arrested. He states that in dogs,
one or two days after section of the nerves, he found the
lacteals filled with chyle after milk had been passed into the
stomach ; but it is now well known that chyle is in great part,
if not entirely, formed in the intestinal canal, without the inter-
vention of the stomach. Another experiment, howev er, is more
interesting. After section of the pneumogastrics, having ex-

1 This observation, first made by Bouchardat and Sandras, in 184Y, has since
been confirmed by many experimenters. Bernard, after dividing the pneumo-
gastrics in the middle region of the neck in a dog which had a large gastric fistula,
gave the animal soup and sugared milk, which he ate with difficulty, and made
many efforts to swallow ; but the matters did not pass into the stomach, and
were soon regurgitated by the mouth (Legons sur la Physiologic et la Pathologie
du Systeme Nerveux, Paris, 1858, tome ii., p. 422). This was one of many experi-
ments made by Bernard with the same results (Lemons de Physiologie Experi-
mentale, Paris, 1856, p. 435).

INFLUENCE OF THE NEKVOTJS SYSTEM ON THE STOMACH. 285

posed the mucous membrane of the stomach, he found that
an acid fluid appeared in parts which were subjected to me-
chanical or galvanic irritation.1 The general results of his ex-
periments on this subject were that after the division of both
pneumogastric nerves, small quantities of food could be di-
gested in the stomach, but that a considerable mass was only
chymified on the surface, the centre not undergoing any altera-
tion. This he attributes, not so much to arrest of secretion
of the gastric juice, as to paralysis of the movements of the
stomach, which, when the mass of food is considerable, are
necessary in order to expose all parts to the action of the
gastric juice.3

The experiments of Bernard on this subject are very clear
and satisfactory. When the mucous membrane of the stom-
ach was turgid with blood, the animal (a dog) being in full
digestion and provided with a large gastric fistula so that
the changes which might take place in the stomach could be
readily observed, the pneuinogastrics were divided in the
neck. At once the mucous membrane became pale and flac-
cid, and the secretion of gastric juice was arrested. When
the animal died after section of the pneumogastrics during
digestion, it was remarked that the absorption of chyle
seemed to have been arrested, the lacteals being found to
contain coagulated chyle even as far as the villi of the intes-
tines.3 According to these experiments, the action of gas-
tric juice which might exist in the stomach at the time of
section of the pneumogastrics would continue, but no new
fluid is secreted ; and if the fluid thus remaining in the
stomach be neutralized, digestion is immediately arrested.
In one experiment in which the pneumogastrics had been
divided, having previously emptied the stomach, Bernard
introduced meat finely divided. The next day the meat had

1 LONGET, TraitS de Physiologic, Paris, 1861, tome i., p. 235.

2 Op. cit., p. 237.

8 BERNARD, Lemons de Physiologic Experimentale, Paris, 1856, p. 438.

286 DIGESTION.

a distinctly ammoniacal odor and an alkaline reaction, as
the result of spontaneous decomposition.1

These experiments show only an immediate arrest of the
secretion of the gastric juice. In certain exceptional in-
stances in which animals survive the section of both nerves
for a number of days, or sometimes even recover, it has been
noted that after a few days an acid secretion again takes
place in the stomach.3

Though much confusion exists in the earlier observations
on the effects of section of the pneumogastrics upon the
stomach, the conclusions to be drawn from more recent ex-
periments are tolerably definite.

There can be no doubt that division of both these
nerves produces immediate and grave disorder in the pro-
cess of stomach-digestion, amounting, it is more than prob-
able, to complete arrest of the secretion of the gastric
juice. Its secretion may be induced again by local stimula-
tion, but the quantity is always greatly diminished. Under
these circumstances, it is possible that very small quantities
of food may be digested in the stomach a day or two after
the operation ; and if the animal survive for a considerable
time,3 the secretion may be to a certain extent reestablished.
Serious trouble in stomach-digestion is produced by the pa-
ralysis of the muscular coats of the stomach consequent upon
section of both pneumogastrics.

1 BERNARD, Legons sur la Physiologie et la Pathologic du Sysieme JWervew,
Paris, 1858, tome ii., p. 418.

2 Ibid.

3 One of the animals operated upon by Bernard lived for seventeen days.

CHAPTEK X.

MOVEMENTS OF THE STOMACH.

Character of the contractions of the muscular coat of the stomach — Movements
in the cardiac and in the pyloric portion — Mechanism of the movements of
the stomach — Rumination, and regurgitation from the stomach — Rumination
in the human subject — Yomitmg — Mechanism of vomiting — Condition of the
stomach during the act of vomiting — Action of the diaphragm in vomiting —
Action of the abdominal muscles in vomiting — Action of the oesophagus in
vomiting — Summary of the muscular action which takes place in vomiting —
Eructation.

As the articles of food are passed into the stomach by the
acts of deglutition, the organ gradually changes its form, size,
and position. "When the stomach is empty, the opposite sur-
faces of its lining membrane are in contact in many parts, and
are thrown into numerous longitudinal folds. As the organ is
distended, these folds are effaced, the stomach itself becom-
ing more rounded ; and as the two ends with the lesser curv-
ature are comparatively immovable, the whole organ un-
dergoes a movement of rotation, by which the anterior face
becomes superior, and is applied to the diaphragm. At this
time the great pouch has nearly filled the left hypochondriac
region, and the greater curvature looks anteriorly, and comes
in contact with the abdominal walls.

Aside from these changes, which are merely due to the
ingestion of food, the stomach undergoes important move-
ments, which continue until its contents have been dissolved
and absorbed, or have passed out at the pylorus. But while
these movements are taking place, the two orifices are guard-
ed, so that the food shall remain .for the proper time exposed

288 DIGESTION.

to the action of the gastric juice. We have already noted
the rhythmical contractions of the lower extremity of the
oesophagus, by which regurgitation of food is prevented ; 1
and the circular fibres, which form a thick ring at the py-
lorus, are constantly contracted, so that, at least during the
first periods of digestion, only liquids and that portion of
food which has been reduced to a pultaceous consistence can
pass into the small intestine. It is well known that this re-
sistance at the pylorus does not endure indefinitely, for indi-
gestible articles of considerable size, such as stones, have
been passed by the anus after having been introduced into
the stomach ; but observation has shown that masses of
digestible matter are passed by the movements of the stom-
ach to the pylorus over and over again, and do not find
their way into the intestine until they have become softened
and broken down.

The contractions of the walls of the stomach are of the
kind characteristic of the non-striated muscular fibres. If
the finger be introduced into the stomach of a living animal
during digestion, it is gently but rather firmly grasped by a
contraction which is slow and gradual, enduring for a few
seconds, and as slowly and gradually relaxing and passing to
another part. The movements during digestion undoubt-
edly present certain differences in different animals ; but
there can be no doubt that the phenomenon is universal, in
spite of the experiments of some physiologists anterior to the
time of Haller, who exposed the organ and always found it
passive. In dogs, when the abdomen is opened soon after
the ingestion of food, the stomach appears pretty firmly con-
tracted on its contents. In a case reported by Todd and
Bowman, in the human subject, in which the stomach was
very much hypertrophied and the walls of the abdomen
were very thin, the vermicular movements could be dis-
tinctly seen. These movements were active, resembling the
peristaltic movements of the intestines, for which, indeed,

1 See page 204.

MOVEMENTS OF THE STOMACH. 289

they were mistaken, as the nature of the case was not recog-
nized during life.1 !Nb argument, therefore, seems necessary
to show that during digestion, the stomach is the seat of
tolerably active movements.

A peculiarity in the movements of the stomach, which
has been repeatedly observed in the lower animals, partic-
ularly dogs and cats, and in certain cases has been con-
firmed in the human subject, is that at about the junction of
the cardiac two-thirds with the pyloric third, there is fre-
quently a transverse band of iibres so firmly contracted as to
divide the cavity into two almost distinct compartments.
It has also been noted that the contractions in the cardiac
division are much less vigorous than near the pylorus ; the
stomach seeming simply to adapt itself to the food by a
gentle pressure as it remains in the great pouch, while in the
pyloric portion, divided off as it is by the hour-glass con-
traction above-mentioned, the movements are more frequent,
vigorous, and expulsive. We must again refer, however, to
the observations of Beaumont for the only accurate descrip-
tion of the movements of the stomach, as they take place
during digestion in the human subject.

The experiments of Beaumont were generally made with
the subject lying on the right side, and the movements of the
stomach were observed by following with the eye a particular
morsel of food as it passed along, or by introducing the bulb
of a thermometer into the organ, and allowing it to move with
the alimentary mass. It was invariably found that the move-
ments of the thermometer-bulb were the same as those ob-
served by identifying and following a particular portion of
food. As the alimentary bolus enters by the cardiac opening,
it turns to the left, descends into the great pouch, and follows
the greater curvature to the pyloric end. It then returns to
the cardiac orifice by the lesser curvature, and takes again
the same course as before. "While these revolutions, so to

1 TODD AND BOWMAN, TJie Physiological Anatomy cpid Physiology of Man,
Philadelphia, 1857, p. 550.
19

290 DIGESTION.

speak, of the alimentary mass are going on, the food is turned
over and over, so that it becomes intimately mixed with the
digestive fluids and subjected to a certain amount of tritura-
tion. This action is undoubtedly of great importance, as
fresh portions of food are thereby continually exposed to the
action of the gastric juice, and the boluses, with their particles
agglutinated to a certain extent in the mouth, are disinte-
grated and penetrated with the gastric fluid in every part.

A marked difference was observed between the move-
ments in the cardiac and in the pyloric portion. "When the
thermometer-bulb arrived at the contracted septum, which
was three or four inches from the pyloric end, it was at first
stopped by the forcible contraction; but in a short time
there was a gentle relaxation which allowed it to pass, when
it was drawn quite forcibly for three or four inches toward the
pyloric opening. "When in this portion of the stomach, the
bulb was firmly grasped and made to undergo a spiral mo-
tion ; and if drawn forcibly out, it gave to the fingers the
sensation of being held by a strong suction force. As soon
as relaxation occurs, the bulb is passed back to the seat of
stricture, and when pulled through this, it moves freely in
the great cavity.

Each one of these revolutions was found to occupy from
one to three minutes. They were slower at first than after
digestion had been somewhat advanced.1

The mechanism of these movements is easily appreciated
when we consider the number and varied direction of the
fibres which form the muscular coat of the stomach, and the
fact that the stomach, when distended, is more or less dis-
placed with every movement of the diaphragm. It is easy
to understand, also, how in the pyloric portion, where the
muscular fibres are thickest and the cavity is comparatively
small and elongated, the movements should be more vigorous
and expulsive than over the rest of the organ. We have
already alluded to the fact that the movements of the stom-

1 BEAUMONT, op. cit., p. 109 at seq.

MOVEMEOTS OF THE STOMACH. 291

ach are animated by the pneumogastric nerves and become
arrested when both these nerves are divided.1

As the result chiefly of the observations of Beaumont, the
following may be taken as a summary of the physiological
movements of the stomach in digestion :

The stomach normally undergoes no movements until
food is passed into its cavity. When food is received, at the
same time that the mucous membrane becomes congested and
the secretion of gastric juice commences, contractions of the
muscular coat begin, which are slow and irregular during
the commencement of stomach-digestion, but become more
vigorous and regular as the process advances. After diges-
tion has become fully established, the stomach is generally
divided by the firm and almost constant contraction of a
transverse band of fibres into a cardiac and a pyloric portion ;
the former occupying about two-thirds, and the latter one-
third of the length of the organ. The contractions of the
cardiac division of the stomach are uniform and rather gen-
tle ; while in the pyloric division they are intermittent and
more expulsive. The effect of the contractions of the stom-
ach upon the food contained in its cavity is to subject it to
a tolerably uniform pressure, with a certain amount of
trituration and agitation, in the cardiac portion, the gen-
eral tendency of the movement being toward the pylorus
along the greater curvature, and back from the pylorus
toward the great pouch along the lesser curvature. At
the constricted part, which separates the cardiac from the
pyloric portion, there is an obstruction to the passage of the
food until it has been sufficiently acted upon by the secre-
tions in the cardiac division to have been reduced to a pul-
taceous consistence. The alimentary mass then passes into
the pyloric division, and by a more powerful contraction
than occurs in other parts of the stomach, it is passed into

1 The question as to how far the sympathetic system of nerves is ever con-
cerned in the movements of the stomach will be considered in treating specially
of the nervous system.

292 DIGESTION.

the small intestine. This completes the distinction between
the two portions of the stomach, the cardiac division only,
as we have already seen, possessing a mucous membrane
capable of secreting the true solvent gastric juice.

"The revolutions of the alimentary mass, thus accom-
plished, take place slowly, by gentle and persistent contrac-
tions of the muscular coat ; the food occupying from one to
three minutes in its passage entirely around the stomach.
Every time that a revolution is accomplished, the contents
of the stomach are somewhat diminished in quantity ; 1 prob-
ably, in a slight degree, from absorption of digested matter
by the stomach itself, but chiefly by the gradual passage of
the softened and disintegrated mass into the small intestine.
This process continues until the stomach is emptied, oc-
cupying a period of from two to four hours ; after which, the
movements of the stomach cease until food is again in-
troduced.

Regurgitation, Vomiting, and Eructation.

Rumination and Regurgitation. — Regurgitation of part
of the contents of the stomach, in the human subject, though
of frequent occurrence, particularly in early life, is not strictly
a physiological act ; and is always due either to overloading
of the stomach or some pathological condition. But in some
of the inferior animals this is habitual ; a certain class, called
ruminants, regularly passing the food, after the first deglu-
tition, in small quantities from the paunch into the mouth,
where it undergoes a second mastication, and is only then
permitted to pass to the secreting stomach and the rest of
the alimentary canal. Animals of this class, examples of
which are the ox, sheep, goat, and the camel and the deer
tribe, are invariably herbivorous, and take into the stomach
a large bulk of matter from which is elaborated a compara-
tively small quantity of nutriment. During the period when
they are nourished by milk, rumination does not take place.

1 BEAUMONT, op. cit., p. 113.

RUMINATION AND EEGUEGITATION. 293

The ordinary food taken by these animals passes, in greatest
part, into the first stomach or rumen ; a small portion, which
consists of the moist and finely divided parts, passes into the
second stomach, but none is received into the third and
the fourth stomach.1 In the first stomach, are thus collected
all the dry and coarse parts of the food, which are here
slowly but continuously agitated by the movements of the
muscular coat Most of the liquids taken and a consider-
able quantity of saliva accumulate in the second stomach, or
reticulum. When the proper quantity of food has been taken,
small quantities are forced by the contractions of the muscu-
lar wall into a canal or groove, which is a continuation of the
oesophagus, and is bounded by two lips capable of closing over
the top, so as to completely separate it from the great cavity.
Here the food is moistened by fluids poured in from the sec-
ond stomach, and a small bolus, moulded by the muscular
contractions of the walls of the canal, is prepared to be passed
back to the mouth. The bolus is then passed along the
oesophagus by the anti-peristaltic contractions of its muscular

1 All ruminating animals have multiple stomachs, generally with four dis-
tinct divisions. The first stomach, called the rumen or paunch, is the most
capacious. It is generally divided into several sacs, and is lined by a mucous
membrane with numerous villi, and covered by a dense layer of epithelium.
The second stomach, called the reticulum, is very much smaller than the first. It
presents in its mucous membrane, a large number of deep polygonal pits, like
the cells of the honey-eomb, and always contains a considerable quantity of
liquid. There is a very free communication between the reticulum and the ru-
men. The third stomach, called the omasum, or psalterium, is ovoid in form, and
its mucous membrane is arranged in folds like the leaves of a book, giving it a
very remarkable appearance. These folds are alternately wide and narrow.
The fourth stomach, called the abomasum, is the true secreting organ. It is lined
by a soft, glandular mucous membrane, and resembles the single stomach of
most mammals. In the camel, in addition to the above compartments, the
stomach is provided with several groups of large sacs attached to the rumen.
These receive only liquids, and are provided with bands of muscular fibres around
their openings, so that their liquid contents may be retained and stored up for
future use. In this animal, the cells of the reticulum are unusually deep, narrow
at their openings, and are capable of being closed by the contraction of mus-
cular fibres situated at their orifices.

294: DIGESTION.

coat, aided by a brisk, powerful, and involuntary contraction
of the abdominal muscles and the diaphragm. Though this
act is aided by the contractions of the oesophagus itself, it can-
not be accomplished without the action of the diaphragm and
abdominal muscles. This has been proven by experiments in
which these muscles have been paralyzed ; when rumination
becomes impossible. The passage of the bolus from the ru-
men to the mouth takes place with great rapidity, and has
nothing of the gradual character which is noted in the peris-
taltic movements of the intestinal canal. In the rumen, con-
trary to the opinion which at one time obtained, the food is
only macerated in the fluids which have been swallowed,
nothing being secreted in its cavity ; but the position of the
reticulum is such as to favor the accumulation in its cavity
of fluids, consisting of salivary secretion which has been
swallowed, and fluids taken as drink. There is no evidence
that there is any fluid secreted in the second stomach.

"When a bolus is thus brought back to the mouth, it un-
dergoes the second mastication, which, in the ox, is gener-
ally something less than a minute in duration. At this time
it is still further moistened by an abundant flow of saliva,
taking place almost entirely from the parotids.

After the second mastication has been accomplished, the
mass is swallowed with great rapidity ; and as it is now
soft, and inconsiderable in size, it does not distend the canal
which passes from the oesophagus to the third stomach so as
to separate the lips and escape into the rumen, but passes di-
rectly into the third stomach, or omasum. In the omasum,
the food is pressed rather forcibly between the leaf-like folds
of the mucous membrane, and gradually passes from this to
the fourth stomach, or abomasum, which is the true stomach
of these animals, and the only one which secretes the gastric
juice. There is no reason to believe that any fluid is se-
creted in the third stomach, the contents of which are always
remarkably dry.

The second deglutition is followed very soon by the pas-

RUMINATION AND EEGHRGITATION. 295

sage of a new bolus to the mouth for rumination ; the inter-
val of time being very short, only from four to five seconds.1
There is considerable difference in the length of time em- '
ployed by different animals in rumination. In the ox, about
one-quarter of the day is thus occupied ; but in the sheep
and the goat the process is much more rapid.2

Additional interest is attached to the function of rumi-
nation in the inferior -animals, in connection with human
physiology, from the fact that an analogous process has
sometimes been observed in the human subject ; though it is
rare and generally connected with a pathological condition.
Such cases have been often quoted, and, in the earlier works
on physiology, were frequently exaggerated ; but a few in-
stances, well authenticated, are on record in which rumina-
tion had become habitual. A very remarkable case of this
kind is reported by Home. The subject was an idiot-boy, aged
nineteen years, who had an appetite so ravenous that it be-
came necessary to restrict the quantity of food. At dinner he
ordinarily ate about a pound and a half of meat and vegeta-
bles, swallowing the whole in two minutes. He began to chew
the cud at the end of a quarter of an hour. The muscles of
the throat could be seen to contract when the bolus was
passed back to the mouth. He chewed the food by two or
three movements of the jaws and then swallowed it again.
This was repeated at intervals for half an hour, during which
time he was always more quiet than usual. The intellect
was so feeble that it was impossible to ascertain whether the
rumination was voluntary or involuntary.3 One of the cases
of rumination most frequently referred to is that of M.
Cambay, who studied the phenomena in his own person, and

1 COLIN, Traite de Physiologic Comparee des Animaux Domestiques, Paris,
1854, tome i., p. 527.

2 COLIN, op. cit., p. 521.

3 HOME, Observations on the Structure of the Stomachs of Different Animals,
with a view to elucidate the Process of converting Animal and Vegetable Substances
into Chyle. — Philosophical Transactions, London, 1807, p. 174.

296 DIGESTION.

made it the subject of an inaugural thesis ; and another is
the case of the brother of M. P. Berard.1 In these instances,
as far as could be ascertained from the sensations during the
act, the regurgitation of food was effected by persistent con-
tractions of the muscular walls of the stomach, assisted by a
slight and almost involuntary contraction of the abdominal
muscles and diaphragm. It is stated by Cambay that in his
case, the taste of the articles of food was not modified, " but
that it is with something of a sense of pleasure that the ru-
minator thus causes to return to the mouth the aliments that
he has taken into the stomach, which makes them undergo
a new trituration." "

Rumination in the human subject is not a physiological
act. It is evident that the substances returned to the
mouth are not impregnated with the gastric juice, for they
have not the disagreeable acid taste of ordinary vomited
matters. The acts are generally preceded by a sense of ful-
ness in the stomach, and their mechanism is probably nearly
the same as that of the regurgitation of small quantities of
milk from the distended stomachs of young children, which
is so common. In the person of Cambay, the first act was
said to be voluntary, but succeeding ones were not under the
control of the will. Undoubtedly the faculty of regurgita-
ting the food may be improved by practice, and we have
known of an instance in which it was apparently cultivated
as an accomplishment.

The mechanism of regurgitation of portions of the con-
tents of the stomach, aside from instances simulating rumi-
nation, has been so often alluded to that it demands in this
connection but a passing mention. In some persons, this act
may be accomplished by a voluntary muscular effort, espe-
cially when the stomach is overloaded. It occasionally hap-
pens, when the stomach is somewhat distended, that a small

1 BERARD, Cours de Physiologic, Paris, 1849, tome ii., p. 274.

2 CAMBAY, TJiese sur le Merycisme et la JDigestibilite des Alimens. — Theses de
Creole de Medccine, Paris, 1830, tome vii., No. 213, p. 10.

VOMITING. 297

portion of its contents suddenly finds its way to the mouth with-
out even the consciousness of the individual. The muscular
contraction which produces this slight regurgitation is so insig-
nificant that there must necessarily have been some relaxation
at the cardiac opening of the stomach, which under ordinary
conditions is, as we know, firmly closed. The act is then pro-
duced, in part by a slight contraction of the abdominal muscles
and diaphragm, and in part by contractions of the stomach
itself and anti-peristaltic movements of the oesophagus. It
has nothing of the violent expulsive character of true vomiting.

Vomiting.'' — The mechanism of vomiting was the subject
of much discussion among physiologists in the early part of
the present century, when the celebrated experiments of
Magendie on this subject were first made. Though Magen-
die was by no means the first to demonstrate the view which
now generally obtains regarding the muscular actions con-
cerned in vomiting, his experiments were of such a striking
character, and so demonstratively conclusive, as to attract the
attention of all physiologists, and to settle, almost beyond
doubt, a question which had before been very uncertain. The
experiments of Bayle, Chirac, Schwartz, and others, which
tended to prove that vomiting is due to contractions of the
abdominal muscles and diaphragm, compressing the stomach,
and not to contractions of the muscular tissue of the stomach
itself, had been recognized and the conclusions adopted by
some physiologists, long before the publication of Magendie's
experiments, in 1813. For example, John Hunter, in the
second edition of his Animal (Economy, published in
1792, says : u We know that the action of vomiting is per-
formed entirely by the diaphragm and abdominal muscles.

5? 2

1 A sufficient apology for considering the act of vomiting (which is undoubt-
edly pathological), so fully as is done in the succeeding pages, is in the fact that
its mechanism is usually treated of in works upon physiology, and is not consid-
ered in treatises upon practical medicine.

2 HUNTER, Observations on Certain Paris of the Animal (Economy, London,
1792, p. 199.

298 DIGESTION.

Nevertheless, the general opinion was, with Haller,1 that in
vomiting, the stomach was emptied chiefly by convulsive
contractions of its intrinsic muscles.

An excellent review of the experiments on the mechan -
ism of vomiting, anterior to the memoir of Magendie, is con-
tained in the report of the commission from the Institut, to
which the subject was referred. The first observations on the
subject were those of Bayle, made in 1681 ; 2 these were fol-
lowed by the confirmatory experiments of Chirac, in 1686,
the later experiments of Schwartz, and many others.8 The
experiments of Bayle consisted in giving animals emetics in
solution in water, and making an incision into the abdomen,
so that when the animal made efforts at vomiting, the finger
could be introduced and placed upon the stomach. "When
this was done, it became evident that the stomach did not
contract during the act by which its contents were expelled ;
and when the abdomen was largely opened, so that the stom-
ach could not be compressed between the diaphragm and the
abdominal muscles, vomiting was impossible. That these
experiments had been recognized by physiologists, is shown
by the passage just quoted from the works of Hunter.

"We can give no better idea of the actual mechanism of
vomiting than by a brief analysis of the memoir of Magendie,
with the various experimental facts by which the views
advanced by him were supported. The first two experi-
ments were merely repetitions of those performed long before
by Bayle and Chirac. After having caused a dog to swal-
low six grains of tartar emetic, when nausea had been ex-
cited, an incision was made in the median line and the finger
was introduced into the abdominal cavity and placed upon

1 HALLER, Elementa Physiologies, Bernse, 1764, tomus vi., pp. 281, 282.

2 MAGENDIE, Memoire sur le Vomissement, lu d la premiere classe de Vlmtilut
de France. — Suivi du Kapport fait a la classe par MM. Cuvier, Huinboldt, Pinel,
et Percy, Paris, 1813, p. 27.

8 HALLER, op. cit., tomus vi., p. 228. Schwartz went further than his prede-
cessors, and showed that the cardiac opening of the stomach was relaxed during
vomiting.

VOMITING. 299

the stomach. At each nausea, the finger was compressed,
but the stomach seemed passive ; and when vomiting took
place and part of the contents of the stomach was dis-
charged, the finger was " compressed with a force really ex-
traordinary." The incision in the abdomen was then en-
larged so that the stomach could be seen. The stomach
became distended with air at each nausea, and when vomit-
ing occurred again, it was compressed without presenting the
slightest contraction of its intrinsic muscular fibres. The air
with which the stomach was distended before each act of
vomiting evidently was introduced by the oesophagus, as
was shown by experiments which have been already quoted.1
In another experiment, four grains of emetic were injected
into the jugular of a dog, a large incision was made into the
abdomen, and the stomach was drawn entirely out so as to
be removed from the pressure of the muscles. Though the
animal made violent efforts at vomiting, the contents of the
stomach were undisturbed, and the organ remained perfectly
motionless and flaccid. Yomiting was then produced by
vigorous pressure of the stomach, outside of the abdomen,
with the hands. In another experiment, the stomach was
drawn out of the abdomen, the vessels carefully ligated, and
the organ extirpated. Into the abdomen was then introduced
a small pig's bladder, to the neck of which was fixed a gum-
elastic tube, which was passed into the oesophagus and se-
cured in that position by threads. About a pint of water was
then introduced into the bladder which was made to take
the place of the stomach, and the wound in the abdomen was
closed with points of the interrupted suture. Emetic was
then injected into the veins, and in a few moments efforts at
vomiting supervened, and the contents of the bladder were
discharged by the mouth. These remarkable experiments
proved conclusively the want of action of the stomach itself
in vomiting, and the mechanism of the discharge of its con-
tents by compression exerted upon it by the abdominal mus-

1 See page 20Y.

300 DIGESTION.

cles and the diaphragm. Other experiments were made,
however, which demonstrated the relative importance of the
different muscles in the performance of this act. The phrenic
nerves were divided in a dog, and the diaphragm was thus
rendered almost inert. On injecting emetic into the veins
after this operation, vomiting took place at times very feebly,
and at times not at all. In another animal, the abdominal
muscles were divided, leaving the viscera confined by the peri-
toneum and the linea alba. Emetic was then injected into the
circulation, and vomiting was effected solely by contractions
of the diaphragm. In this experiment, after having divided
the phrenic nerves, vomiting ceased, though the nausea con-
tinued.

These experiments, which were satisfactorily repeated
before a commission from the Institut, consisting of Cuvier,
Humboldt, Pinel, and Percy, are as conclusive as any that
ever have been made upon living animals. Since their
publication, they have been repeated by a number of physi-
ologists, among whom may be mentioned Begin,1 Legallois,
and Beclard.2 We are also enabled to testify to their ac-
curacy from personal observation ; and in the fall of 1861
they were in part repeated in the course of lectures on phys-
iology before the class of the Bellevue Hospital Medical Col-
lege, and an animal was caused to vomit from a pig's blad-
der which had been substituted for the stomach.3

If any thing further were needed to establish the great
importance of the action of the abdominal muscles and
diaphragm in vomiting, and the insignificant part played by
the stomach itself in this operation, it could be furnished by
facts relating to the mode of contraction of the muscular
fibres which constitute the middle coat of the stomach, and

1 Dictionnaire des Sciences Medicales, in 60 vols., Paris, 1822, tome Iviii., Ar-
ticle Vbmissement.

2 LEGALLOIS, Experiences sur le Vomissement. — (Euvres, Paris, 1824, tome ii.,
p. 93 et seq.

3 These experiments were made simply for class-demonstration, and have
never before been published.

VOMITING. 301

cases of disease in which, it has been impossible for contrac-
tions of the stomach to take place. It is well known that
the characteristic mode of contraction of the striated, volun-
tary muscles is rapid, violent, and followed by sudden relaxa-
tion ; and that where it becomes necessary, in the performance
of any of the vegetative functions, that such muscular action
should take place, as in the action of the heart in propelling
the blood forcibly into the arterial system, the striated mus-
cular fibre is found. On the other hand, the characteristic
mode of contraction of the non -striated, involuntary muscular
fibre is gradual, enduring for a certain time, and followed by
a slow relaxation. These facts point at once to the kind of
muscles which we would suspect to be engaged in the pro-
duction of vomiting. The act is always violent, sudden, and
convulsive, and is entirely inconsistent with the mode of con-
traction of non-striated muscles, as it has been observed in
other situations.

A remarkable case is mentioned by Longet, in which a
young girl, with the intent to commit suicide, swallowed a
large quantity of a mineral acid. She vomited continually
up to the time of her death ; and in the vomited matters were
found numerous shreds of the coats of the stomach. At the
autopsy it was found that the stomach had been destroyed,
except little portions of its walls, which were adherent to
the surrounding parts. These were united to the adjacent
viscera and the walls of the abdomen by inflammatory ex-
udation, so as to form a cavity which was not a stomach,
but which communicated freely with the oesophagus. Yet
this patient, without a contractile stomach, vomited freely
during the last hours of her life.1

A case of extrusion of the stomach, reported by Lepine,
in 1S44,2 is often misquoted so as to make it appear that the

1 LONGET, Traile de Physiologic, Paris, 1861, tome i., p. 141.

2 LEPINE, Plaie penetrante de V abdomen ayante donne issue d Tistomac, d Pare
du colon, et d V epiploon, guerie en vingtet un jours, suivi de reflexions mr levomissc-
ment. — Bulletin de P Academic Royale deMedecine, Paris, 1843-'44, p. 1 46 et seq.

302 DIGESTION.

contractions of the stomach itself are sufficient to produce
vomiting.1 In this case, the stomach, containing food and
air, was protruded from the abdomen by a large wound. It
remained motionless while violent and ineffectual efforts at
vomiting were made, during the wThole time that it was thus
out of the abdomen, and could not be excited to contrac-
tion, even by gentle irritation ; but when the stomach was
returned into the abdominal cavity, vomiting instantly took
place.

All the facts bearing on this subject go to show that in
true vomiting, contractions of the muscular coats of the
stomach are not necessary, are not definitely connected
with the act, and are never capable of discharging any part of
the contents of this viscus. On the contrary, the observa-
tions of Magendie seem to show that the stomach is rather
relaxed than contracted during efforts at vomiting.2

1 CARPENTER, Principles of Human Physiology, Philadelphia, 1853, p. 408,
TODD AND BOWMAN, The Physiological Anatomy and Physiology of Man, Philadel-
phia, 1857, p. 565, and KIRKES, Manual of Physiology, Philadelphia, 1857, p. 195.
These authors quote the case reported by Lepine as presenting contractions of the
stomach itself, with discharge of part of its contents, while it remained out of the
abdominal cavity. Brinton ( Cyclopaedia of Anatomy and Physiology, London, 1859,
vol. v., supplement, p. 317) notices and corrects this error in previous quotations.
The case is also correctly quoted by Dunglison (Human Physiology, Philadelphia,
1856, p. 205), and by Milne-Edwards (Lecons sur la Physiologic, Paris, 1860, p.
333).

2 MAGENDIE, Memoiresur le Vomissement, Paris, 1813, p. 12. Both Carpenter
and Todd and Bowman, base their opinion that the muscular walls of the stomach
are active in vomiting mainly upon the case reported by Lepine ; the former
quoting extensively from the original source, but the latter crediting the quotation
to "Paget's Eeport for 1845." Carpenter says : " The stomach, having wholly
protruded itself, it was seen to contract itself repeatedly and forcibly during the
space of half an hour, until by its own efforts it had expelled all its contents
except gases " (p. 408) ; and the same is said by Todd and Bowman, who speak
of the reporter as L'Epione (p. 565, note). In the original account of the case
referred to, there is no such statement ; but, on the contrary, the reporter says (p.
148) : " Thus, during all the time that the stomach remained out of the abdom-
inal cavity, there did not take place any apparent contraction of the muscular
fibres of this viscus, and nothing that it contained was expelled from its cavity,
notwithstanding the violent efforts at vomiting that the patient made. Hardly

VOMITING. 303

More importance is to be attached to the action of the
oesophagus in vomiting than is usually assigned to it by
writers. The following remark by Hunter, on this point,
is interesting : " The muscles of the cavity of the abdomen
act, in which is to be included the diaphragm ; so that
the capacity of the abdomen is lessened, and the action
of the diaphragm rather raises the ribs ; and there is also an
attempt to raise them by their proper muscles, to make a
kind of vacuum in the thorax, so that the oesophagus may be
rather opened than shut, while the glottis is shut so as to
let no air enter the lungs.1 A little reflection will make it
evident that the descent of the diaphragm, the most power-
ful of the inspiratory muscles, with the glottis firmly closed,
makes a virtual vacuum in the chest, by the force of which,
a canal so dilatable as the oesophagus would undoubtedly be
distended. This action must powerfully assist in vomiting,
by drawing the food into the oesophagus and by dilating
the cardiac opening, which, as we have seen, is ordinarily
closed. Experiments, particularly those of Beclard and of
Legallois, have further shown that there is a violent and ex-
tensive contraction of the longitudinal fibres of the oesoph-
agus with each act of vomiting. This was demonstrated
by dividing the oesophagus near the stomach, drawing it out
at a wound in the neck, and causing the animal to make
efforts at vomiting, by injecting emetic into the veins. "With
each act, the oesophagus was observed to undergo sudden
and marked contraction in its length.2 This act assists in
vomiting, as the shortening of the oesophagus has a tendency

had the stomach been returned into the belly, when the same effort produced ex-
pulsion of aliments."

It is remarkable that the authors of the above-mentioned excellent and com-
prehensive works upon physiology should have been content to take a quotation
so important as the one in question at second-hand, when a reference to the origi-
nal would have enabled them to avoid making an important statement precisely
opposite to the fact.

1 HUNTER, op. cit.t p. 200.

1 LEGALLOIS, (Euvres, Paris, 1824, tome ii., p. 91.

304 DIGESTION.

to dilate the cardiac opening of the stomach, and counteract
the contraction of the pillars of the diaphragm.

It has been found "by Magendie that' during the nausea
which precedes the act of vomiting, there is always distension
of the stomach from deglutition of air.1 This may be some-
times absent in the human subject, when vomiting occurs
very suddenly ; but in all Magendie's experiments upon ani-
mals, he found that immediately after an act of vomiting,
the stomach was flaccid, but that when another effort was ap-
proaching, and during the nausea which preceded, the organ
became gradually distended. Distension of the stomach
from deglutition of air previous to the act of vomiting was
observed in the case of extrusion of the stomach reported by
Lepine.2 It is unnecessary to repeat the observations by
which it was shown that the air enters by the oesophagus ;
as they have already been referred to under the head of deg-
lutition.3

Summary. — The symptoms which precede the act of
vomiting are sufficiently familiar. Usually they commence
with a peculiar sensation of depression and general malaise,
known as nausea. This is frequently accompanied by slight
pain in the region of the epigastrium, feeble pulse, cold and
clammy perspiration, and pallor. There is also usually an
increase in the flow of saliva. Retchings and the peculiar
acts by which air is forced into the stomach are frequent,
and immediately before the vomiting takes place, there is
generally a violent inspiration, followed by spasmodic closure
of the glottis. Yiolent and convulsive expulsion of a part^
or the whole of the contents of the stomach by the mouth,
which is widely opened, then takes place. This is accom-
plished by spasmodic contractions of the diaphragm, the

1 MAGENDIE, Memoire sur la Deglutition de I1 Air atmospherique, lu d Vlnsti-
tut, le 26 octobre, 1813, p. 4.

2 LEPINE, loc. cit., p. 149.
8 See page 207.

VOMITING. 305

longitudinal fibres of the oesophagus, and the abdominal
muscles. The muscular coats of the stomach itself are re-
laxed, or, at all events, their contraction has no marked in-
fluence in the expulsion of its contents.

The most important muscle concerned in this act is the dia-
phragm ; and it has been shown that this muscle alone is capa-
ble of producing vomiting when the abdominal muscles have
been divided.1 The action of the diaphragm is to forcibly
press the stomach against the anterior wall of the abdomen
and the linea alba, at the same time, by its descent, forming
a tendency to a vacuum in the chest and dilating the oesoph-
agus,— as the air cannot enter the lungs, owing to closure
of the glottis. The contractions of the longitudinal fibres of
the oesophagus are probably important in assisting to relax the
cardiac opening of the stomach, counteracting, at the same
time, the contractions of the pillars of the diaphragm. The
contractions of the abdominal muscles assist in expelling the
contents of the stomach, but are much less effectual than the
contractions of the diaphragm. It has been shown that they
are frequently incapable, in themselves, of producing vomit-
ing when the diaphragm has been paralyzed. They always
act, however, as can be readily observed by simple external
examination.

The vomited matters pass readily into the mouth, and
seldom, if ever, into the glottis, which is firmly closed. The
velum is generally contracted and applied to the pharynx so
as to protect the nasal passages ; but this is not always effec-
tual, for matters sometimes pass into the nose when the act
is very sudden or when the mouth is not sufficiently opened.

After the act has been accomplished by one, or several
successive contractions, it is followed immediately by a pro-
longed expiration and a sense of relief from the distressing
nausea. It is frequently repeated, however, at intervals

1 In birds, the abdominal muscles perform the most important part in vomit-
ing.

20

306 DIGESTION.

more or less remote, when the phenomena take place in the
order just described.

The act of vomiting is undoubtedly induced by causes
which operate through the nervous system, and a full con-
sideration of these properly belongs to another division of
this work. The impression produced by the irritant emetics
is conducted to the nervous centre and gives rise to a stimu-
lus which is sent to the muscles concerned in the act. The
transmission takes place in part through the pneumogastrics,
though this is not the only channel, for vomiting may be
thus induced after division of these nerves. It is by no
means necessary that an impression should be made upon
the stomach, as is shown by efforts at vomiting after the
stomach has been extirpated. Irritation of some of the sym-
pathetic nerves, particularly the abdominal ganglia, will pro-
duce vomiting. Traction upon the oesophagus, the irritation
produced by biliary calculi, uterine disorders, etc., may pro-
duce the same result. Yomiting is very common in cerebral
disturbances ; and this is undoubtedly the first cause of or-
dinary sea-sickness. When vomiting results from titillation
of the fauces, the impression is conveyed to the nervous
centre and is reflected to the muscles concerned, in the same
way. These facts show that there are many avenues for the
passage of these impressions to the nervous centres. The
action of emetics which operate through the blood is not re-
flex, but the vomiting is probably induced by the direct im-
pression made by these substances on the nervous centres.

Eructation. — The discharge of gases from the oesopha-
gus by the mouth, accompanied with a peculiar and charac-
teristic sound, is very common. This is usually accomplished
without any marked effort of the muscles concerned in vom-
iting, and evidently requires very little force. Usually, the
cardia is so effectually closed as to prevent the passage even
of gases ; and in eructation, there 'must be a temporary relax-
ation of this opening. When thus relaxed, the act is accom-

VOMITING. SOT

plished chiefly by contractions of the stomach and oesopha-
gus. It is generally accompanied or preceded by sensible
convulsive movements of the oesophagus, involving, possibly,
contractions of its longitudinal fibres, which would favor re-
laxation of the cardiac opening. Though usually involun-
tary, this act is sometimes under the control of the will.
When it occurs, while it is difficult or impossible to prevent
the discharge of the gas, the accompanying sound may be
readily suppressed. Eructation is frequently a matter of
habit, which in many persons becomes so developed by prac-
tice, that the act may be performed voluntarily at any time.

CHAPTEE XI.

INTESTINAL DIGESTION.

Physiological anatomy of the small intestine — Size of the small intestine — Divi-
sions of the small intestine — Mucous membrane of the small intestine — Yal-
vulae conniventes — Glands of Brunn — Intestinal tubules, or follicles of Lieber-
kiihn — Intestinal villi — Solitary glands, or follicles, and the patches of Peyer
— Intestinal juice — Secretion of the solitary and agminated glands — General
properties of the intestinal juice — Action of the intestinal juice in digestion.

Physiological Anatomy of the Small Intestine.

THE small intestine, so called on account of its small size
as compared with, the rest of the intestinal tract, is the long
cylindrical tube which occupies the greatest part of the
abdominal cavity. This must now be regarded as the most
important division of the digestive system ; and its physiolo-
gical anatomy, together with that of the great glands which
discharge their secretions into its cavity, are indispensable as
an introduction to the study of intestinal digestion. As it is
in the small intestine that the final elaboration of most of
the alimentary principles takes place, and here also that these
principles are taken into the circulating fluid, we will find,
in our study of its anatomy, certain parts which are con-
cerned in digestion, and others which, as far as we know, are
connected only with the function of absorption. It will be
most convenient, however, to consider, in this connection, all
the structures found in the small intestine, which possess
physiological interest.

The small intestine, extending from the pyloric ex-
tremity of the stomach to the ileo-csecal valve, is held to the

INTESTINAL DIGESTION. 309

spinal column by a double fold of serous membrane, called
the mesentery. As the peritoneum which lines the cavity
of the abdomen passes from either side to the spinal col-
umn, it comes together in a double fold just in front of the
great vessels along the spine, and passing forward, splits
again into two layers, which become continuous with each
other and enclose the intestine, forming its external coat.
The width of the mesentery is usually from three to four
inches ; but at the commencement and the termination of
the small intestine, it suddenly becomes shorter, binding the
duodenum and that portion of the intestine which opens into
the eaput coli closely to the subjacent parts. The mesentery
thus keeps the intestine in place, but allows of a certain
amount of motion, so that the tube may become convoluted,
accommodating itself to the size and form of the abdominal
cavity. The form of these convolutions is irregular and is
continually changing.

The length of the small intestine, in situ, is probably
from fifteen to eighteen feet ; 1 but the canal is very disten-
sible, and its dimensions are subject to constant variations.
When separated from the mesentery, and measured with-
out stretching, its length has been found to be, on an average,
about twenty feet. Its diameter is about one and a quarter
inches.2

This part of the alimentary canal has been divided into
three portions, which present anatomical and physiological
peculiarities, more or less marked. These are the duodenum,
the jejunum, and the ileum.

The duodenum has received its name from the fact that

1 See page 134, note.

2 Dr. Brmton made the last-named estimates from measurements of something
less than forty human intestines. " In making these, the healthy intestine was
laid upon a board, and spread out to what seemed a proper width, before taking
its length. (Cyclopcedia of Anatomy and Physiology, London, 1859, vol. v., sup-
plement, p. 340.) Sappey, from measurements in four cases, estimates the
length of the small intestine at about twenty-six feet. ( Traite d'Anatomie Do
scriptivc, Paris, 1857, tome iii., p. 124.)

310 DIGESTION.

it is about the length of the breadth of twelve fingers, i. e.,
from eight to ten inches. This portion of the intestine is
considerably wider than the constricted pyloric end of the stom-
ach, with which it is continuous, and is also much wider than
its continuation, the jejunum. It presents a curve, which is
ordinarily described by anatomists as consisting of three por-
tions. The first, called the hepatic or ascending portion, is
about two inches in length. This is much less firmly fixed
by its peritoneal attachment than the other portions, and is
nearly covered by the serous membrane. Its direction is
outward, backward, and slightly upward. Turning down-
ward, and a little inward, it merges into the second, called
the descending or vertical portion, the length of which is
about three inches. This is covered with peritoneum only on
its anterior surface, and is somewhat more firmly attached
than the ascending portion. The intestine then makes a sec-
ond bend, and the third or the transverse portion is
horizontal in its course, passing across the spine into the left
hypochondrium. This portion is about five inches in length.
It is narrower than the others, is but partially covered by
peritoneum, and is more firmly bound down than any other
part of the small intestine.

The coats of the duodenum, as of the other divisions of
the intestinal tube, are three in number. Commencing ex-
ternally, we have the serous, or peritoneal coat, which has
already been described. The middle, or muscular coat, is
composed of the involuntary or unstriped muscular fibres,
such as exist in the stomach, arranged in two layers. The
external, longitudinal layer is not veiy thick, and the direc-
tion of its fibres can be made out easily, only at the outer
portions of the tube, opposite the attachment of the mesen-
tery. Near the mesenteric border, the fibres are very faint.
This is true throughout the whole of the small intestine ;
though the fibres are most numerous in the duodenum. The
internal, circular, or transverse layer of fibres is considerably
thicker than the longitudinal layer. These fibres encircle

MUCOUS MEMBRANE OF THE SMALL INTESTINE. 311

the tube, running, for the most part, at right angles to the
external layer, but some of them having rather an oblique
direction. The circular layer is thickest in the duodenum ;
diminishing gradually in thickness to the middle of the
jejunum, but after that maintaining about a uniform thick-
ness throughout the canal, to the ileo-caecal valve.

The jejunum, the second division of the small intestine, is
continuous with the duodenum. It presents no well-marked
line of separation from the third division, but is generally
considered to include the upper two-fifths of the small in-
testine, the lower three-fifths being called the ileum. It has
received its name from the fact that it is almost always
found empty after death. This portion of the intestine pre-
sents no important peculiarities as regards its peritoneal and
muscular coat.

The ileum is somewhat narrower and thinner than the
jejunum ; otherwise possessing no marked peculiarities except
in the structure of its mucous membrane. This opens into
the commencement of the colon, and is the termination of
the small intestine.

Mucous Membrane of the Small Intestine. — The mucous
coat of the small intestine is somewhat thinner than the
lining membrane of the stomach. It is thickest in the duode-
num, and gradually becomes thinner till we reach the ileum.
It is highly vascular, presenting, like the mucous membrane
of the stomach, a great increase in the quantity of blood
during the process of digestion. It has a peculiar soft and
velvety appearance, and during digestion, is of a vivid red
color, being pale pink during the intervals. It presents for
anatomical description the following parts : 1, folds of the
membrane, called valvulse conniventes ; 2, duodenal race-
mose glands, or the glands of Brunn ; 3, intestinal tubules,
or the follicles of Lieberkuhn ; 4, intestinal villi ; 5, solitary
glands or follicles ; 6, agminated glands, or the patches of
Peyer.

312 DIGESTION.

The valvulge conniventes, simple transverse duplicatures
of the mucous membrane of the intestine, are particularly
well marked in man, though they are found in some of the
inferior animals belonging to the class of mammals, as the
elephant and the camel.1 They render the extent of the
mucous membrane much greater than that of the other coats
of the intestine. Commencing at about the middle of the
duodenum, they extend, with no diminution in number,
throughout the jejunum. In the ileum they become more
and more rare, until they are lost at about its lower third.
Sappey found about six hundred of these folds in the first
half of the small intestine, and from two hundred to two
hundred and fifty in the lower half. He estimates that in
those portions of intestine where they are most abundant,
they increase the length of the mucous membrane to about
double that of the tube itself ; but in the ileum they do not
increase the length more than one-sixth.2 The folds are
always transverse and occupy usually from one-third to one-
half of the circumference of the tube, though a few may ex-
tend entirely around it. The greatest width of each fold is
in the centre, where it measures from a quarter to half an
inch. From this the width gradually diminishes until the
folds are lost in the membrane as it is attached to the mus-
cular coat. Between the folds are found fibres of connective
tissue similar to that which attaches the membrane through-
out the whole of the alimentary tract. This, though loose,
is constant, and prevents the folds from being effaced, even
when the intestine is distended to its utmost. Between the
folds are also found vessels, nerves, and lymphatics.

The position and arrangement of the valvulae conniventes
is such that they move freely in both directions, and may be
applied to the inner surface of the intestine either above or
below their line of attachment. It is evident that the food,

1 MILNE-EDWAKDS, Lemons sur la Physiologie ct I1 Anatomic Comparee, Paris,
1860, tome vi., p. 393.

2 SAPPEY, Traite d1 Anatomic Descriptive, Paris, 1857, tome iii., pp. 134, 135.

MUCOUS MEMBEANE OF THE SMALL INTESTINE. 313

as it passes along in obedience to the peristaltic movements,
must, by insinuating itself beneath the folds and passing over
them, be exposed to a greater extent of mucous membrane
than if these valves did not exist. This is about the only
definite use which can be assigned to them. They cannot,
as has been supposed by some, have any considerable influ-
ence on the rapidity of the passage of the alimentary mass
along the intestinal canal.

Thickly set beneath the mucous membrane in the first
half of the duodenum, and scattered here and there through-
out the rest of its extent, are the duodenal racemose glands,
or the glands of Brunn. These are not found in other parts
of the intestinal canal. In their structure, they closely re-
semble the racemose glands of the oesophagus. On dissect-
ing the muscular coat from the mucous membrane, they may
be seen with the naked eye in the areolar tissue, in the form
of little rounded bodies, about one-tenth of an inch in diam-
eter. Examined microscopically, these bodies are found to
consist of a large number of short blind tubes ramifying in
every direction and held together by a small quantity of
fibrous tissue. The tubes have blood-vessels ramifying on their
exterior and are lined with glandular epithelium. They col-
lect together to terminate in an excretory duct which pene-
trates the mucous membrane and opens into the intestinal
cavity. When these structures are examined in a perfectly
fresh preparation, the excretory duct is frequently found to
contain a clear viscid mucus, of an alkaline reaction. This
secretion has never been obtained in quantity sufficient to
admit of the determination of its chemical or physiological
properties. Its quantity must be infinitely small compared
with the quantity of secretion produced by the glandular
tubes found in such immense numbers throughout the intes-
tinal tract ; and it cannot be regarded as constituting an im-
portant part of the fluid known as the intestinal juice.

The intestinal tubules, or the follicles of Lieberkuhn, the

314 DIGESTION.

most important glandular structures in the intestinal cavity }
are found throughout the whole of the small and large intes-
tine. In examining a thin section of the mucous membrane,
these little tubes are seen closely packed together, occupying
nearly the whole of its structure. From the great extent of
the membrane, it can readily be conceived that their number
must be immense. Between the tubules are blood-vessels
embedded in a dense stroma of fibrous tissues with numerous
of the unstriped muscular fibres. In a vertical section of the
mucous membrane, the only situations where the tubules are
not seen are in that portion of the duodenum where the
space is occupied by the ducts of the glands of Brunn, and
immediately over the centre of the larger solitary glands
and some of the closed follicles which are collected to form
the patches of Peyer. The tubes are not entirely absent in
the patches of Peyer, but are collected in rings, twenty or
thirty tubes deep, which surround each of the closed follicles.
A microscopical examination of the surface of the mucous
membrane by reflected light shows that the openings of the
tubules are between the villi.

In their anatomical characters, the tubules closely resemble
the tubes of the stomach, especially those found in the py-
loric portion. They are composed externally of a structure-
less basement membrane, and are lined with a single layer of
columnar epithelium like the cells which cover the villi ; the
only difference being that in the tubes the cells are a
little shorter. These cells never contain fatty granules, even
during the digestion of fat. The central cavity which the
cells enclose, which is about one-fourth of the diameter of the
tube, is filled with a clear viscid fluid, wThich is the most im-
portant constituent of the intestinal juice. The length of
the tubules is equal to the thickness of the mucous membrane,
and is about -f-g of an inch. Their diameter is about ^F of
an inch. In man they are cylindrical, terminating in a sin-
gle, rounded, blind extremity, which is frequently a little
larger than the rest of the tube. These tubules are the chief

MUCOUS MEMBBANE OF THE SMALL INTESTINE. 315

agents concerned in the production of the fluid known as the
intestinal juice.

The intestinal villi, though chiefly concerned in absorp-
tion, are most conveniently considered in this connection.
These exist throughout the whole of the small intestine, but
are not found beyond the ileo-csecal valve, though they
cover that portion of the valve which looks toward the ileum.
Their number is very great, and they give to the membrane
its peculiar and characteristic velvety appearance. They are
found on the valvulse conniventes as well as the attached por-
tions of the mucous membrane. In the duodenum and jeju-
num, they are most numerous. In these parts, there are from
fifty to ninety villi to a square line, and in the ileum, from
forty to seventy to a square line.1 Sappey estimates, on an
average, about fifty to the square line, and more than ten
millions (10,125,000) throughout the whole of the small in-
testine.8 The form of the villi varies somewhat in different
animals. In the human subject, they are flattened cylinders
or cones. In the duodenum, where they resemble somewhat
the elevations found in the pyloric portion of the stomach,
they are shorter and broader than in other situations, and are
more like flattened conical folds. In the jejunum and ileum,
they are in the form of long flattened cones and cylinders.
As a rule, the cylindrical form predominates in the lower
portion of the intestine. In the jejunum they attain their
greatest length, measuring here from s\ to j\ of an inch in
length, by TV to T£7 of an inch in breadth at their base.

The structure of the villi shows them to be simple eleva-
tions of the mucous membrane, provided with blood-vessels,
and probably also with lacteals, or intestinal lymphatics.
Externally is found a single layer of long columnar epithe-
lial cells, resting on a structureless basement membrane.

1 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 325.

8 SAPPEY, Traite d'Anatomie Descriptive, Paris, 1857, tome iii., p. 140. Sap-
pey estimated twelve to fourteen villi to a square millimetre, which gives, ap
proximatively, about fifty to a square line.

316 DIGESTION.

These cells, though closely adherent to the subjacent parts
during life, are easily removed after death, and are almost
always destroyed and removed in injected preparations.
They adhere firmly to each other, and are isolated with diffi-
culty in miscroscopic preparations. Kolliker has shown that
the membranes on the free surfaces of these cells are thick-
ened and finely striated, forming, as it were, a special mem-
brane covering the villus and external to the cells. This
membrane may be raised up from the cells and exhibited by
the action of water.1

The substance of the villus is composed of a stroma of
amorphous matter, in which are embedded nuclei and a
few fibres, fibro-plastic cells, and numerous non-striated mus-
cular fibres. The blood-vessels are very numerous ; four or
five, and sometimes as many as twelve or fifteen artereoles
entering at the base, ramifying through the substance of the
villus, but not branching or anastamosing, or even diminish-
ing in calibre, until by a slightly wavy turn or loop they
communicate with the venous radicles, each of which is some-
what larger than the arterioles. The veins all converge to
two or three branches, finally emptying into a large trunk
which occupies the centre of the villus.2

The nuclei of the muscular fibres of the villi may be
shown by treating them with acetic acid after the epithelium
has been removed. These fibres appear to be longitudinal,
forming a thin layer surrounding the villus, about half way
between the periphery and the centre, and continuous with
the muscular coat of the intestine. The muscular fibres,
from their arrangement, would seem to be capable of short-

1 KOLLIKER, op. cit., p. 328. These observations were made by Kolliker in
1855. In 1842, Goodsir described and figured an appearance on the free ends
of the epithelium covering the villi, which he said was like a membrane cover-
ing the cells, though he did not distinctly assert the existence of such a mem-
brane. ( On the Structure of the Intestinal Villi in Man and certain of the Mam-
malia, with some Observations on Digestion, and the Absorption of Chyle. — TJie
Edinburgh New PhilosophicalJournal, 1842, vol. xxxiii., p. 167.)

2 SAPPEY, Traite d"1 Anatomic Descriptive, Paris, 185V, tome iii., pp. 144, 145.

MUCOUS MEMBRANE OF THE SMALL INTESTINE.

317

ening the villus, and this has actually been observed in speci-
mens taken from the intestine shortly after death.

Fig. 2.

The anatomy of the lac-
teals as they originate in the
villi has been the subject of
much controversy ; but almost
all anatomists are now agreed
that these vessels commence
either by a plexus or by blind
extremities, and have no di-
rect openings into the intesti-
nal cavity. The most gener-
ally received view at the pres-
ent day is that the lacteals
originate by a single delicate,
nearly straight vessel in each
villus; and that this vessel
has no ramifications in the
villus itself, but commences
by a single, rather dilated,
blind extremity near the
apex.

Owing to the excessive te- been partially withdrawn by contrac-
nuity of the Walls of the lac- tion from its investing epithelium,

the villi — if indeed

Intestinal villi, as seen by transmit-
ted light. The villus, marked 1, has

which is thus left entire like the finger
of a glove.

a, epithelium of the villus ; 6, gran-
ular matrix, or substances of the same.
(BRINTOX, Cyclopaedia of Anatomy and
Physiology, London, 1859, vol. v., sup-
plement, p. 354.)

teals in

they exist at all — it has been
found impossible to fill them
with an artificial injection,
though the lymphatics sub-
jacent to them may be easily
distended and studied in this way. Those who profess to have
seen the single lacteal in the villus have done so by examining
the parts when the lacteal system has been engorged with
chyle. It seems, however, from a careful review of the whole
subject, that the view entertained by Sappey is most nearly

318 DIGESTION.

correct. This observer, having tried all methods of artificial
injection of the lacteals of the villi, came to the conclusion
that nothing was to be learned from examinations of the
mucous membrane after death. He then examined the villi
of a dog in which the entire lacteal system was engorged
with chyle, securing the chyle in the parts by ligatures
applied to the principal trunks. "When he examined the
mucous membrane, he found it white, as though it had been
sprinkled with milk, and the villi engorged and in a sort of
erection. On placing some of these villi between two plates of
glass and examining them with a magnifying power, he saw
them divide, while under observation, into two portions ; a
peripheral portion, occupied by loops of blood-vessels, and a
central, white portion, which had a cylindrical or ellipsoidal
form. It is this central portion which has been taken for the
single lacteal by most anatomists ; but Sappey believes that
this is an illusion ; and that the white appearance is produced
simply by the pressure of the glass forcing the chyle which
is in the peripheral portion out of the villus, while the fluid
is imprisoned in the central portion. The figures given by
Kolliker certainly have the appearance described by Sap-
pey ; and if the lacteals really commence by a single dilated
vessel, they have no analogue in other parts of the lymphatic
system.

Sappey, while unable to demonstrate lacteals in the intes-
tinal villi, infers their existence from analogy with the papillae
of various parts. The reason why they cannot be injected in
the intestine is because the soft tissue in which they are em-
bedded affords no support to their walls. As regards their
mode of origin, we are disposed to adopt the opinion of
Sappey, that they commence by a delicate anastamosing
plexus situated outside the blood-vessels.1 This is the way
in which lymphatics have been shown to arise in the papillae
of the skin and other parts in which the density of the sur-

1 SAPPEY, op. cit.,tome iii., p. 149 et seq.

MUCOUS MEMBRANE OF THE SMALL INTESTINE. 319

rounding structures will admit of these vessels being filled
with injection.

~No satisfactory account has ever been given of nerves in
the intestinal villi. If any exist in these structures, they
probably are derived from the sympathetic system, which
is largely distributed to the intestinal canal.

The solitary glands or follicles and the patches of Peyer,1
or agminated glands, have one and the same structure ; the
only difference being that those called solitary are scattered
singly in very variable numbers throughout the small and
large intestine, while the agminated glands consist of num-
bers of these follicles collected into patches of different sizes.
These patches are generally found in the ileum. The number
of the solitary glands is so variable that it is impossible to give
any general estimate of it. They are sometimes absent. The
patches of Peyer are always situated in that portion of the
intestine opposite the attachment of the mesentery. They
are likewise variable in number, and are irregular in size.
They are usually irregularly oval in form, and measure from
half an inch to an inch and a half in length, by three-
fourths of an inch in breadth. Sometimes they are three or
four inches long, but the largest are always found in the
lower part of the ileum. Their number is about twenty, and
they are usually confined to the ileum ; but when they are
very numerous — for they sometimes exist to the number of
sixty or eighty — they may be found in the jejunum, or even
in the duodenum.

Two varieties of these patches have been lately described

1 These patches, or collections of closed follicles in the intestine are generally
called the patches or glands of Peyer, after the anatomist who described them, in
1677. It is admitted that Peyer was not their discoverer, as they had been ob-
served by Severin, Wepfer, and particularly by Grew, an English anatomist, in
1676 ; but the description by Peyer was so much more accurate and- satisfactory
than the observations of his predecessors, that the glands have since been
called by his name. The work of Peyer is reprinted in the Bibliothcca Anato-
mica, by Clericus and Mangetus, tomus i., p. 150. This is entitled, Exertitatio
Analomico-Medica Prima, de Grlandulis Intestinorum adjecta, est Anatome Venfri-
culi Gallinacei.

320 DIGESTION.

by anatomists. In one of these varieties, the patch is quite
prominent, its surface being slightly raised above the general
mucous surface, while in the other, the surface is smooth,
and the patch is distinguished at first with some difficulty.
The more prominent patches are covered with mucous mem-
brane arranged in folds something like the convolutions on
the surface of the brain. The valvulse conniventes are ar-
rested at or very near their borders. These are the only
patches which are generally described as the glands of Peyer ;
the others, which may be called the smooth patches, being
generally overlooked. The latter are covered with a smooth,
thin, and closely adherent mucous membrane. Their follicles
are small and numerous. The borders of these patches are
much less strongly marked than those of the first variety. As
they are evident only upon close examination, and as they
are the only patches present in certain individuals, it is said
that sometimes the patches of Peyer are entirely wanting.
They are generally less numerous than the first variety, and,
according to Sappey, are most abundant in persons of feeble
constitution.1 The villi are very large and prominent on the
mucous membrane covering the first variety of Peyer's
patches, especially at the summit of the folds. In the sec-
ond variety, the villi are the same as over other parts of the
mucous membrane, except that they are placed more irreg-
ularly and are not so numerous.

The intimate structure of these bodies has not been defi-
nitely settled in all its particulars. It is well determined,
however, that the follicles which compose them are com-
pletely closed ; the openings which have been said to exist
being undoubtedly accidental ruptures made in preparing
the specimen for microscopic examination. These follicles
are somewhat pear-shaped, with their pointed projections
directed toward the cavity of the intestine. Just above
the follicle, there is generally a small opening in the mu-
cous membrane, surrounded by a ring of intestinal tubules,

1 SAPPEY, op. cit., tome iii., p. 175.

MUCOUS MEMBKANE OF THE SMALL INTESTINE. 321

and leading to a cavity, the base of which is convex and
formed by the conical projection of the wall of the follicle.
The diameter of the follicles is from 7V to ^\ or even TV of
an inch.1 The small-sized follicles are generally covered by
mucous membrane and have no opening leading to them.
Each follicle consists of a rather strong capsule composed of
an almost homogeneous, or very slightly fibrous membrane,
enclosing a semi-fluid grayish substance, cells, blood-vessels,
and probably lymphatics. The semi-fluid matter is of an
albuminoid character. The cells are very small, rounded,
and mingled with numerous small free nuclei. The blood-
vessels have rather a peculiar arrangement. In the first
place they are distributed between the follicles, so as to form
a rich net-work surrounding each one. Numerous capillary
branches are sent from these vessels into the interior of the
follicle, returning in the form of loops. The obscurity in the
anatomy of the follicles is chiefly with regard to the arrange-
ment of their lymphatic vessels. These have not been dis-
tinctly traced within the investing membrane. They have
been demonstrated surrounding the follicles, but it is still
doubtful whether they exist in their interior. This ques-
tion is so unsettled that it is impossible to make a definite
statement on the subject. All that is known is that during
digestion the number of lacteals coming from the Peyerian
patches is greater than at other parts ; but vessels containing
a milky fluid are never seen within the follicles.

The mucous membrane covering the prominent patches
is generally so thick and folded that the closed follicles can-
not be seen from above and are only discernible from the
under surface. In the smooth patches, the follices are gen-
erally well brought out by maceration in acetic acid.

The description of the follicles which compose the patches
of Peyer answers, in general terms, for the solitary glands,
except that the latter are found in both the small and large
intestine.

1 KOLLIKER, op. cit., p. 332.
21

322 DIGESTION.

Intestinal Juice.

Of the three fluids with, which the food is brought in con-
tact in the intestinal canal, namely, the bile, the pancreatic
juice, and the intestinal juice, the last, the secretion of
the mucous membrane of the intestine, presents the greatest
difficulties in the investigation of its properties and function.
If it be admissible to reason from the known mechanism
of secretion in other parts, it is fair to suppose that the
normal secretion from the mucous membrane of the intestine
can only take place in obedience to the stimulus of food.
The same cause induces the secretion of the pancreatic juice,
and increases the flow of bile. As we have already seen, the
food, as it passes from the stomach into the duodenum, is to
a great extent disintegrated and mingled with the secretions
from both the mouth and the stomach. Under these circum-
stances, it is evidently impossible, in the present state of the
science, to collect the intestinal juice under perfectly phys-
iological conditions, in a state of purity sufficient to allow of
extended experiments regarding its composition, properties,
and action in digestion. It is for these reasons that we
cannot regard the observations of Frerichs and Bidder and
Schmidt as, of themselves, throwing much light upon the
properties and function of the fluid under consideration.

Frerichs attempted to collect the intestinal juice in the
following way : He drew out from the abdomen of a living
animal a loop of the small intestine, from four to eight
inches in length, which was emptied, carefully cleaned by
repeated washings with warm water, and isolated by two
ligatures. The intestine was then returned to the abdomi-
nal cavity, the animal was killed after a few hours, and the
contents of the isolated portion examined. These experi-
ments were made upon dogs and cats, during the intervals of
digestion. The fluid contained in the portion of intestine
situated between the ligatures was found to be transparent,
colorless, and viscid, with a strongly alkaline reaction. It

JUICE. 323

possessed, to a certain degree, the property of transforming
starch into sugar, but the intensity of its action in this re-
spect was very variable. It also imperfectly emulsified the
fats and had some action upon the albuminoids. The gen-
eral conclusion arrived at by Frerichs was that the intestinal
juice was not very active in digestion.1

The method of studying the intestinal juice employed by
Bidder and Schmidt more nearly fulfilled the necessary phys-
iological conditions. They experimented upon dogs and
cats, shutting off from the intestine the bile and pancreatic
juice, and found that when starch was introduced into the
canal it became transformed into sugar. They also ob-
served that fat was emulsified to a considerable degree, and
that albumen and meat were partially disintegrated and di-
gested.2 These observers were unable to collect the intesti-
nal juice in quantity sufficient for analysis ; and regarded
the fluids which were obtained in quantity by Frerichs as
the result of pathological action. That which they obtained
was found to be colorless, very viscid, and strongly alkaline
in its reaction.

As far as the composition and general properties of the
intestinal juice are concerned, the observations of Colin upon
horses are the most definite, though it is questionable whether
he succeeded in obtaining the fluid in a normal state. To
collect the fluid, an incision was made into the abdominal
cavity, and from four and a half to six feet of the small in-
testine were drawn out. This portion was emptied by gently
pressing with the finger from above downward, while with
the other hand the upper portion was kept closed. Without
removing the fingers, two soft clamps were then applied, thus
shutting off the exposed part of the intestine from the rest
of the canal. The gut was then returned and the wound in
the abdomen closed. At the end of half an hour, the animal

1 FRERICHS, Verdauung. — WAGNER'S Handworterbudi der Physiologic, Braun-
schweig, 1846, Bd. iii., S. 832.

2 BIDDER UNO SCHMIDT, Die Verdauungssafte, Leipzig, 1852, S. 270 et seq.

324: DIGESTION.

was killed by bleeding, and the contents of the isolated portion
of the intestine were examined. The quantity of juice obtained
was considerable, being from 1,235 to 1,852 grains for about six
and a half feet of intestine. It was always found to be
much less when intestinal digestion had been suspended, and
its quantity could be increased by the injection into the loop
of a little solution of manna, sulphate of soda, or aloes.
The fluid thus obtained was clear, a little yellowish, with a
saline taste and an alkaline reaction. It was mixed with
mucus, which formed a sediment when the fluid was allowed
to stand, and could be separated by filtration.1

Notwithstanding the care with which these observations
were conducted, it is not probable that the fluid thus ob-
tained by Colin was the normal intestinal juice ; and it cer-
tainly does not correspond in its general characters with the
fluids which have been studied by other experimenters.

It becomes an interesting question, in this connection, to
determine whether the solitary and the agminated glands
produce any secretion which is discharged into the intestinal
cavity. Though these follicles are closed, the observations
of Colin have shown pretty conclusively that they are capable
of producing a secretion ; but the precise mode of its forma-
tion is not so apparent. The experiment by which this was
demonstrated was made on a pig, an animal in which there
is an enormous agminate gland, ribbon-shaped, and over six
feet in length. That portion of the ileum in which the
gland is situated was emptied, and about four and a half feet
of it isolated by two ligatures from the rest of the canal. At
the end of an hour the animal was killed and the intestine
examined. The surface of the gland was found covered with
a layer of mucus, thicker and more consistent than over other
portions of the membrane.2 The only way in which it could
reasonably be supposed that this secretion was produced is by

1 COLIN, Traile de Physiologic Comparee, Paris, 1854, tonae i., p. 648 et seq.

2 Loc. tit.

INTESTINAL JUICE. 325

exhalation through the membranes of the follicles ; as there
is no evidence that their contents are discharged by rupture.

Taking only into consideration experiments upon animals,
little definite information has been obtained concerning the
composition and properties of the intestinal juice. We can
readily see that this must be the case, since it has thus far
been impossible, in observations of this kind, to fulfil the
necessary physiological conditions. Further facts were evi-
dently needed to harmonize the opposite results arrived at
by different experimenters. It was the same in the progress
of the physiology of stomach-digestion, which was unsettled
and obscure until the normal gastric juice was obtained by
Beaumont. The case of intestinal fistula reported by Busch,
to which reference has already been made, has done much to
elucidate this subject.1

The case referred to was that of a woman, thirty-one years
of age, who, in the sixth month of her fourth pregnancy,
was injured in the abdomen by being tossed by a bull. The
wound was between the umbilicus and the pubes, presenting
two contiguous openings connected with the intestinal canal.
It was supposed that the openings were into the upper third
of the small intestine. At the time the patient first came
under observation, every thing that was taken into the stom-
ach was discharged by the upper opening, and all attempts
to establish a communication between the two by a surgical
operation had failed. At this time the patient was extremely
emaciated, had a voracious appetite, and was evidently suf-
fering under defective nutrition resulting from the constant
discharges of alimentary matter from the fistula. Having
been treated, however, by the introduction of cooked aliment-
ary substances into the opening connected with the lower

1 BUSCH, Beilrag zur Physiologic der Verdauungsorgane. — VIRCHOW'S Archiv,
Berlin, 1858, Bd. xiv., S. 140 et seq. An analysis of these observations, embra-
cing most of the interesting points, is contained in the American Journal of the
Medical Sciences, July, 1860, p. 217, and in the North American Medico- Chirur-
gical Review, of th£ same date.

326 DIGESTION.

end of the intestine, she soon improved in her nutrition, and
was then made the subject of extended and interesting ob-
servations upon intestinal digestion.

With regard to the general properties of the intestinal
juice, the observations of Busch upon this case agree with
those of Bidder and Schmidt upon the lower animals. He
never, in the natural condition, found a large quantity of se-
cretion in the intestine. The fluid was white or of a pale
rose-color, consistent, and always strongly alkaline. The
maximum proportion of solid matter which it contained was
T'4: and the minimum 3'8T per cent.1 The secretion could
not apparently be obtained in sufficient quantity for ultimate
analysis.

!Nb better opportunity than this could be presented for
studying the intestinal juice in its pure state. The nature
of the case made it impossible that there should be any ad-
mixture of food, pancreatic juice, bile, or the secretion of the
duodenal glands ; and during the process of digestion, the
'lower part of the intestine undoubtedly produced a fluid of
perfectly normal character. "When we come to consider the
action of the intestinal juice upon the various articles of food,
our most reliable facts will be drawn from the observations
made upon this case.

From what has been ascertained by experiments upon
the lower animals and observations on the human subject,
the intestinal juice has been shown to possess the following
characters :

Its quantity in any portion of the mucous membrane
which can be examined is small ; but when the extent of the
canal is considered, it is evident that the entire quantity of
intestinal juice must be great, though beyond this, no reliable
estimate can be made.

The intestinal juice is viscid, and has a tendency to ad-

1 YIRCHOW'S Archiv, 1858,' S. 156.

INTESTINAL JUICE. 327

here to the mucous membrane. It is generally either color-
less or of a faint rose tint, and its reaction is invariably al-
kaline.

With regard to the composition of the intestinal juice,
little of a definite character has been learned. All that can
be said is that its solid constituents exist in the proportion
of about 5*4:7 parts per hundred.1 In most analyses of fluids
from the intestine, there is reason to believe that the normal
intestinal juice was not obtained.2

The organs which secrete the fluid known as the intes-
tinal juice are the follicles of Lieberkuhn, the glands of
Brunn, the solitary follicles, and the patches of Peyer. The
fluid, however, is chiefly secreted by the follicles of Lieber-
kuhn, which, as we have seen, exist in the mucous mem-
brane of the intestine in immense numbers. Though the
other organs mentioned do not contribute much to the secre-
tion, they produce a certain quantity of fluid; and the intes-
tinal juice must be regarded as a compound fluid, like the
saliva, and not the product of a single variety of glands, like
the gastric juice.

Action of the Intestinal Juice in Digestion.

The physiological action of the intestinal juice has been
closely studied in the inferior animals by Frerichs and Bid-
der and Schmidt ; but their experiments have been some-

1 BUSCH, loc. cit.

2 Colin (op. cit., tome i., p. 649) gives the following analysis by Lassaigne of
intestinal fluid taken from the horse. The mode in which this fluid was obtained
by Colin has already been referred to. The fluid was collected in large quantity,
and it seems probable, especially since the observations of Busch, that it \vas not
the normal intestinal juice. Its specific gravity was 1,010 at 60° Fahr.

Water ' . 98-10

Albumen 0*45

Chloride of sodium ~\

" " potassium I 1>46

Phosphate of soda

Carbonate of soda 100 '00

328 DIGESTION.

what contradictory. All observers, however, are agreed that
this fluid is more or less active in transforming starch into
sugar. But we must turn finally to the observations of
Busch on the case of intestinal fistula in the human subject
for the most satisfactory and definite information on this sub-
ject. In many points, it is true, these observations simply
confirm those which have been made upon the inferior ani-
mals, but they are of great value, as they establish conclu-
sively many important facts regarding the action of the
intestinal juice in the human subject.

In this case, starch, both raw and hydrated, when intro-
duced into the lower opening, where it came in contact only
with the intestinal juice, was invariably changed into glu-
cose. Cane-sugar was not transformed into glucose, but ap-
peared in the faeces as cane-sugar. This is important, with
reference both to the want of action of the intestinal -juice
upon cane-sugar, and the fact that cane-sugar, as such, is not
absorbed in quantity by the intestinal mucous membrane.

Coagulated albumen and cooked meat were always more
or less digested by the intestinal juice. This fact coincides
with the observations of Bidder and Schmidt.

The observations which were made on fats, melted but-
ter, and cod-liver oil, showed that the pure intestinal juice
had little or no action upon them. These substances always
appeared in the faeces unchanged. "When, however, fatty
matters were taken into the stomach, they were discharged
from the upper opening in the intestine in the form of a very
fine emulsion, and could not be recognized as fat.

It is evident from these facts that the intestinal juice is
important in digestion, more as a fluid which aids the gen-
eral process as it takes place in the small intestine, than as
one which has a peculiar action upon any distinct class or
classes of alimentary principles. It undoubtedly assists in
completing the digestion of albuminoid substances and in
transforming starch into sugar. Although, in the latter
process, its action is very marked, the same property belongs

ACTION OF THE INTESTINAL JUICE IN DIGESTION. 329

to the saliva and the pancreatic juice. Intimately mingled
— as it always is during digestion — with the bile and the
pancreatic juice, as well as with various alimentary sub-
stances, the intestinal juice should be studied as it operates
upon the food, in connection with the other fluids found in
the small intestine ; the digestive action of all being most in-
timately associated.

CHAPTEE XII.

PANCREATIC JTJICE.

Pancreatic ducts — Mode of obtaining the pancreatic juice — General properties
and composition of the pancreatic juice — Alterations of the pancreatic juice —
Action of the pancreatic juice in digestion — Action upon fats — Destruction
of the pancreas — Cases of fatty diarrhoea — Action of the pancreatic juice
upon starchy and saccharine principles — Action upon nitrogenized principles
— Summary of the functions of the pancreas in digestion.

THE physiological anatomy of the pancreas will not de-
mand a very extended consideration, as most of the points of
its descriptive anatomy have no direct relation to its phys-
iology, and its minute anatomy belongs properly to the sub-
ject of secretion. The pancreas is a glandular organ, situ-
ated transversely in the upper part of the abdominal cavity,
closely applied to its posterior wall. Its form is elongated,
with an enlarged thick portion, called the head, which is at-
tached to the duodenum, a body, and a pointed extremity,
which is in close relation to the hilum of the spleen. Its
average weight is from four to five ounces ; its length is about
seven inches ; its greatest breadth about an inch and a half ;
and its thickness three-quarters of an inch.1 It lies behind the
peritoneum, which only covers its anterior surface.

According to Bernard, who has made numerous investi-
gations into the anatomy of this gland, there are nearly
always, in the human subject, two ducts opening into the

1 HYDE SALTER, Cyclopcedia of Anatomy and Physiology, London, 1859, vol.
v., supplement, p. 83.

PAKCREATIC JUICE. 331

duodenum ; 1 one which opens in common with the ductus
communis choledicus, and one which opens about an inch
above the main duct, called by Bernard the recurrent or ac-
cessory duct. The main duct is about an eighth of an inch
in diameter, and extends along the body of the gland, be-
coming larger as it approaches the opening. The second
duct is smaller, and becomes diminished in calibre as it nears
the duodenum. Many anatomists describe but a single duct,
regarding the other as anomalous. The dissections of Ber-
nard, however, were very numerous, and show the almost
constant occurrence of two ducts.2

In general appearance and minute structure, the pancreas
is like the parotid and submaxillary glands. By the older
anatomists it was known as the " abdominal salivary gland,"
on account of this resemblance in structure and an assumed
similarity in the nature of their secretions. Recent develop-
ments in the physiology of the pancreatic juice have caused
this name to be discarded.

It is only since it has been established by Bernard that
one of the most important of the properties of the pancreatic
juice is its power of emulsifying liquid fats, that the experi-
ments of the older physiologists on the pancreas have assumed
any great interest. In the elaborate work of Longet,3 is
a long quotation from Regnerus de Graaf, showing that this
physiologist collected fluid from the pancreas in a living dog,
in 1662. Following De Graaf, there were others who adopt-

1 BERNARD, Memoirs sur le Pancreas, Paris, 1856, p. 9. The fact of the al-
most constant existence of two pancreatic ducts in the human subject is now
recognized by several anatomists. Sappey, out of sixteen dissections of the hu-
man pancreas, found, in one instance, a supplementary duct which had no com-
munication with the duodenum, so that it was really in this case but a branch of
the main duct. In all other instances, there were two ducts, as described by
Bernard. — ( Traite tf Anatomic Descriptive, Paris, 1857, tome iii., p. 248.)

2 In dogs and in many other animals, two ducts exist ; so that both must be
ligated when it is desired to shut off the pancreatic secretion from the intestine.

3 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 256.

332 DIGESTION.

ed the same method of experimentation. The operative pro-
cedure consisted simply in making an incision into the ab-
dominal cavity, tying the intestine near the pylorus and a
little distance below the opening of the pancreatic duct,
opening the canal, and introducing a duck's quill into the
orifice of the pancreatic duct. By arranging a little vial in
such a position that fluid would drop into it from the quill,
De Graaf collected in this way from a dog, two drachms,
and even half an ounce of fluid in seven or eight hours. The
fluid thus obtained was sometimes acid, very often acid and
salt, and sometimes nearly insipid. Though, as has been so
conclusively shown by Bernard, the experiment of De Graaf
was nearly correct in principle, the fluid which he called
pancreatic juice lacked the constant and necessary property
of the normal secretion, namely, alkalinity.1

It is not necessary to detail the observations of all those
who, since De Graaf, have obtained fluid purporting to be pan-
creatic juice. Most of the early observations on this subject
were made with a view of proving either that the secretion
of the pancreas was or was not identical with the saliva,
and have no immediate bearing on our knowledge of the
true function of this organ. Magendie repeated the experi-
ment of De Graaf, but did not succeed in obtaining any
fluid. He operated by simply exposing the orifice of the
pancreatic duct and collecting with a pipette a few drops
of liquid as it flowed. He obtained thus only a small quan-

1 KEGNERUS DE GRAAF, Tradatus Anatomico-Medicus de Sued Pancreatici
Natura et Usu. Ludg. Batavorum, Ex Officina Hackiana, 1671. In this curious
and interesting treatise, which is quite elaborate, the anatomical characters of
the pancreas are minutely described, the opinions of various authors concerning
its uses are discussed, experiments to obtain the pancreatic juice are detailed
with great care, and the properties of the fluid in health and disease are fully
considered. The whole is illustrated with a number of excellent engravings.
The process for obtaining the pancreatic juice so closely resembles that em-
ployed at the present day, that it is surprising that the normal fluid was not pro-
cured. Though De Graaf indicated very nearly the proper way to obtain pan-
creatic juice from a living animal, he developed little or nothing concerning ita
properties and functions.

PANCREATIC JUICE. 333

tity, but enough to determine its alkaline reaction and -its
partial coagulability by heat.1 In 1824, Leuret and Las-
saigne obtained a considerable quantity of pancreatic juice
from the horse, by incising the abdomen, exposing the ductus
communis choledicus with the pancreatic duct, and introdu-
cing into the latter a gum-elastic tube, which was secured in
place by a ligature. They found the fluid alkaline, and made
an analysis of it, which is now quoted in many works on phys-
iology. The digestive properties of the secretion were not
observed.2 Tiedemann and Gmelin obtained fluid from the
pancreatic duct of a dog, by drawing out the duodenum and
pancreas by an opening into the abdomen, and introducing
into the duct a small glass tube. In this way they collected
a little over one hundred and fifty grains in four hours. The
first few grains of fluid were reddish and had an acid reac-
tion. The greater part was clear and faintly alkaline, this re-
action, however being attributed to a change in the secretion,
owing to the sufferings of the animal.3 These authors give
no idea of the physiological properties of the fluid.

The above represents the state of the science concerning
the function and properties of the pancreatic juice prior to
1846, when Bernard first made his experiments on this sub-
ject. I^ot only was the function of the pancreas unknown,
but the ideas concerning the composition of the pancreatic
juice were vague and uncertain and based upon contradic-
tory observations. Bernard was the first to obtain normal
pancreatic juice from a living animal and give a definite
idea of its properties and functions ; a fact which it is proper
to particularly insist upon, inasmuch as since his discovery

1 MAGENDIE, Precis filemenlaire de Physiologic, Paris, 1836, 4me edition,
tome ii., p. 470. An account of this observation is also given in a previous
edition, which appeared in 1817.

2 LEURET ET LASSAIGNE, Recherches Physiologiques et Chimiques pour servir
d VHistoire de la Digestion, Paris, 1825, p. 102 et seq.

3 TIEDEMANN ET GMELIN, Recherches Experimentales Physiologiques et Chi-
miques svr la Digestion, Paris, 1827, premiere partie, p. 27 et seq.

334: DIGESTION.

some have pretended that the facts which he established had
been demonstrated before.1 The following method for col-
lecting the pancreatic juice from a living animal, one which
we have repeatedly employed with success, is essentially that
recommended by Bernard :

The animal generally employed by Bernard in these ex-
periments is the dog. Selecting one of tolerably large size,
he is secured to the operating table, and placed upon his left
side. An incision from three to four inches in length is then
made in the right hypochondrium, just below and parallel
with the border of the last rib. The parts are first divided
down to the fascia transversalis and the peritoneum. An
opening is then made into the abdominal cavity about half
the length of the incision through the skin and muscles;
which brings to view the duodenum and a portion of the
pancreas. The duodenum, with the pancreas attached to it,
is then carefully drawn out of the abdomen. The next step
is to introduce a small canula into the principal pancreatic
duct. In the dog, there are always two pancreatic ducts : a
small one, which opens into the intestine at or near the open-
ing of the bile-duct, and a principal duct, which is situated
about an inch below. To collect the juice, the tube should be
introduced into the principal duct. This is found by turning
the duodenum and pancreas so as to expose the posterior sur-
face of the gland, when the duct, which is very short and al-
most concealed by the tissue of the pancreas, may be seen
obliquely penetrating the intestinal wall. In the dog, the
pancreas is composed of two portions ; one, called the hori-
zontal portion, which is attached to the duodenum, and a ver-
tical p'ortion, which passes away from the intestine between
the folds of the mesentery. The duct is generally situated
near the point where the pancreas ceases to be attached to
the intestine. The tissue of the pancreas is to be carefully

1 BERNARD, Memoirs sur le Pancreas, Paris, 1856. — Lemons de Physiologie Ex-
perimentale, Paris, 1856. — Lepons sur les Proprietes Physiologiques et Ics Altera-
tions Patholoyiques des Liquides de I* Organismc, Paris, 1859:

PANCEEATIC JUICE.

335

pushed away from the duct with the end of the canula or
the point of a knife, a small longitudinal slit is made in it
with the scissors, and a silver canula about one twelfth of an
inch in diameter and four inches in length is introduced and
firmly secured in place by a ligature which has previously
been thrown around the duct. The canula should be pro-
vided with a well-fitting stylet, with the point rounded 30
that it may be introduced into the duct with ease ; and the
end of the canula should be somewrhat roughened, so that the
ligature may secure it well in place. The canula will enter
the duct for a short distance only, and it should not be intro-
duced forcibly.

Fig. 8.

Full-grown shepherd-dog (female), in which a pancreatic fistula has been
established.

A, silver tube to which a bladder has been attached ;— B, bladder;— C, stop-
cock for the purpose of collecting the juice which accumulates in the bladder,
(BERNARD, Lemons de Pliydologie Experimental e, Paris, 1856, tome ii.,.p. 197.)

336 DIGESTION.

After this lias been accomplished, the canula may be
steadied by attaching it with a single stitch to the wall of the
intestine. The stylet is now to be withdrawn and the parts
carefully returned to the abdomen, leaving the end of the
canula projecting at the anterior portion of the wound,
which should now be carefully closed. Bernard recommends
to first raise up the fascia and peritoneum with hooks and
carefully attach their edges with sutures ; and then to close,
in the same way, the incision in the muscles and integument.

The animal may now be kept upon the table, and the
fluid which is discharged from the tube collected in a test-
tube, or a thin gnm-elastic-bag may be attached. This
may be provided with a stop-cock, so that the fluid may be
drawn off at will.

Like the other digestive fluids, the pancreatic juice is only
secreted in abundance during the process of digestion. It is
therefore necessary to feed the animal moderately about an
hour before the operation, so that the pancreas may be in full
activity. When it is exposed at that time, it is filled with
blood and has a rosy tint, contrasting strongly writh its pale
appearance during the intervals of digestion.

In performing the above experiment, it is generally better
not to employ an anaesthetic agent, as this almost always
produces vomiting, arrests digestion for a time, and conse-
quently interferes with the secretion of the pancreatic juice.
This, however, is not always the case. We have sometimes
performed the operation with the aid of ether and obtained
a fair amount of fluid. It is also necessary to avoid traction
upon the duodenum as much as possible, for this is almost sure
to produce vomiting. To obtain the best results, the opera-
tion should be performed rapidly and with very little expo-
sure of the pancreas. In some very successful experiments,
Bernard has obtained from sixty to one hundred grains of
juice in an hour, from a dog of medium size.1

1 BERNARD, Memoire sur le Pancreas, Paris, 1856, pp. 46, 47.

PANCREATIC JUICE. 337

Some of the most interesting facts developed by Bernard
concerning the pancreatic juice relate to phenomena con-
nected with its secretion. It is important to remember that
the secretion of the pancreas is entirely suspended during
the intervals of digestion. This fact has been definitely
settled by Bernard,1 and can easily be observed by opening
animals in digestion and while fasting. In the first instance
the pancreatic duct will be found full of normal secretion,
and in the other, it will be almost, if not entirely, empty.
Bernard has also found that the pancreatic juice begins to
flow into the duodenum during the first periods of stomach-
digestion, before alimentary matters have begun to pass in
quantity into the intestine.

Another important fact determined by Bernard is that
the secretion of the pancreas is readily modified by irritation
and inflammation following the operation. When we come
to treat of the general properties of the normal pancreatic
fluid, it will be seen that its characteristics are, decided
alkalinity, viscid consistence, and coagulability by heat. It
is almost always the case that a few hours after the canula
is fixed in the duct, the juice loses some of these characters
and flows in abnormal quantity. "With respect to suscepti-
bility to irritation, the pancreas is peculiar ; and its secretion
is sometimes abnormal from the first moments of the experi-
ment, especially if the operative procedure has been pro-
longed and difficult. That the properties above given are
characteristic of the normal pancreatic secretion, there can
be no doubt ; as in all instances, fluid taken from the pan-
creatic duct of an animal suddenly killed while in full di-
gestion is strongly alkaline, viscid, and coagulable by heat.
This excessive sensitiveness of the pancreas has rendered
fruitless all the attempts of Bernard to establish a permanent
pancreatic fistula from which the normal juice could be
collected.2

1 Op. tit., p. 43.

2 A number of physiologists have attempted to establish a permanent com-

22

338 DIGESTION.

General Properties and Composition of the Pancreatic
Juice. — In all the inferior animals from which the pancreatic
secretion has been obtained in a normal condition, the fluid
has been found to present pretty uniform characters. It is
viscid, slightly opaline, and has a distinctly alkaline reaction.
Bernard found the specific gravity of the fluid from the
dog to be 1,04:(V The quantity of organic matter which the
normal secretion contains is very great, so that the fluid is
completely solidified on the application of heat. This great
coagulability is one of the properties by which the normal
fluid may be distinguished from that which has undergone
alteration.

Composition of the Pancreatic Juice of the Dog?

Water 900 to 920

Organic matter precipitable by alcohol, and \ ^ 'TS-fiO

containing always a little lime (pancreatine) )
Carbonate of soda,
Chloride of sodium, I ! 10 to ^

Chloride of potassium, I

Phosphate of lime, 1,000 1,000

Most of the analyses which have been made of the pan-
creatic fluid are not to be relied upon, as the manner in which

munication with the pancreatic duct. It is true that a fistula may be maintained
in this situation for several days, but the fluid which is collected from it is usu-
ally abnormal. It is for this reason that some observations on the properties of
the pancreatic juice, particularly those of the German physiologists, are opposed
to those of Bernard ; for the fluids with which they operated were not the same.
Colin (Traite de Physiolcgie Comparee, Paris, 1854, tome i., p. 633) has been
to a certain extent successful in establishing fistulas in animals of the bovine
species. In one instance he made observations on the flow of the pancreatic
juice in a young ox for six days. According to the observations of Colin, in all
cases where a tube is introduced into the pancreatic duct, ulceration takes place
at the site of the ligature and the tube falls out six or eight days after the op-
eration.

1 Op. dL, p. 55.

2 BERNARD, Memoire sur le Pancreas, Paris, 1856, p. 60. The arrangement
of this table has been altered from the original in order to make it correspond
with the tables of the composition of the other digestive fluids.

PANCREATIC JUICE. 339

the juice was obtained shows generally that it was not nor-
mal. There is no doubt, however, that the fluid which was
obtained from the dog and analyzed by Bernard possessed all
the characteristic physiological properties.

The chemical properties of the organic principle of the
pancreatic juice are distinctive. Though, like albumen, it is
coagulated by heat, the strong mineral acids, and absolute
alcohol, it differs from albumen in the fact that its dried al-
coholic precipitate can be redissolved in water, giving to the
solution all the physiological properties of the normal pan-
creatic secretion. Bernard has also found that pancreatine is
coagulated by an excess of sulphate of magnesia, which will
coagulate caseine but has no effect upon albumen. It is im-
portant to recognize this distinction between pancreatine and
other nitrogenized principles, especially albumen, from the
fact that the last-named substance has the property of forming
an emulsion with fats, though not so readily and completely
as the pancreatic juice ; and it is essential to decide whether
the organic principle is a peculiar and distinct substance, or
albumen transuded, pathologically perhaps, from the blood.
There can be no doubt, in view of the marked chemical and
physiological peculiarities of pancreatine, that this is a dis-
tinct proximate principle, characteristic of the pancreatic
secretion and found in no other fluid,

Researches have likewise shown that pancreatine is the
essential physiological constituent of the pancreatic juice,
and the only one which gives this fluid its peculiar digestive
properties. The contents of the duodenum, as the partly
digested matters pass from the stomach, are generally acid ;
but this does not at all interfere with the action of the pan-
creatic juice. Though the secretion itself is alkaline, it re-
tains its physiological properties when it has been rendered
acid by admixture with gastric juice.1

The inorganic constituents of the pancreatic juice do not
possess any great physiological interest, inasmuch as they do

1 BERNARD, Memoire sur le Pancreas, Paris, 1856, p. 67.

340 DIGESTION.

not seem to be essential to its peculiar digestive properties.
It has been shown, indeed, by Bernard, that the organic prin-
ciple alone, extracted from the pancreatic juice and dissolved
in water, is capable of imparting to the fluid all the physio-
logical characters of the normal secretion.

The entire quantity of pancreatic juice secreted in the
twenty-four hours has been variously estimated by different
authors. After what has been said concerning the variations
to which the secretion is subject, it is not surprising that
these estimates should present great differences. Bernard
was able to collect from a dog of medium size from eighty to
one hundred grains in an hour ; 1 but it must be remembered
that only one of the ducts was operated upon, and that the
gland is always very susceptible to irritation. There is no
accurate basis for an estimate of the quantity of pancreatic
fluid secreted in the twenty-four hours in the human subject,
or of the quantity necessary for the digestion of a definite
amount of food.

Unlike the gastric juice, the secretion of the pancreas,
under ordinary conditions of heat and moisture, rapidly
undergoes decomposition. In warm and stormy weather the
alteration is marked in a few hours ; but at a temperature
of from 50° to 70° Fahr., it decomposes gradually in from
two to three days. The changes which the fluid thus under-
goes are interesting, from the fact that some physiologists,
having experimented with an altered or an abnormal secre-
tion, have failed to recognize certain of the characteristic
properties of the normal fluid.2 As it thus undergoes decom-
position, the fluid acquires a very offensive putrefactive odor,
and its coagulability diminishes, until finally it is not affected
by heat. The alkalinity, however, increases in intensity ; and

1 Loc. cit.

2 FRERICHS, in WAGNER'S Handworterbuch der Physiologic, Braunschweig,
1846, Bd. in., S. 848. It is stated by this author that the pancreatic juice does
not emulsify fats more readily or completely than many other animal fluids. The
juice which he used was undoubtedly abnormal, as it was not coagulable by
heat.

ACTION OP THE PANCREATIC JUICE IN DIGESTION. 341

when neutralized with an acid, there is a considerable evo-
lution of carbonic acid ; which does not occur in fresh pan-
creatic juice.

A reaction peculiar to decomposed pancreatic juice is
described by Bernard. On the addition of a small quantity
of chlorine-water, a red color is produced which disappears
in an excess of the reagent.1 The color is intense in propor-
tion to the extent to which decomposition of the organic
matter has advanced ; except, however, when the process of
putrefaction has arrived at its last degree, when the exces-
sive alkalinity interferes with the reaction, and the color
only appears when the fluid has been neutralized with an
acid.2

Action of the Pancreatic Juice in Digestion.

It is only since the observations of Bernard, in 184:8, that
the pancreatic juice has been regarded as a fluid of any great
importance in digestion. It has now been demonstrated,
both by cases of disorganization of the pancreas in man, and
by experiments on animals, in which the tissue of the organ
has been destroyed, that the pancreatic juice is essential to
digestion and to life ; animals dying of inanition when its
function has been abolished.

The most striking feature in the discovery made by Ber-
nard was the action of the pancreatic juice in the digestion
of fats ; it being shown that these principles are acted upon
almost exclusively by the pancreas, and that they pass
through the alimentary canal undigested when this organ
has been destroyed. For this reason, probably, the action of
-the pancreas in the digestion of fatty substances has received

1 BERNARD, op.,cit., p. 57.

2 This reaction with chlorine was observed by Tiedemaun and Gmelin (Re-
cherches Experimental™, etc., Paris, 1827, tome L, p. 41); but these authors re-
garded it as one of the properties of the normal secretion. Bernard does not
assume to have been the first to observe the peculiar color produced by chlo-
rine, but simply to have pointed out the fact that it occurs in the decomposed,
and not in the normal secretion.

342 DIGESTION.

an undue prominence ; and its action upon other articles of
food, though not at the present day overlooked, does not
always receive proper consideration. We shall find that the
pancreatic juice has an important action in the digestion of
nearly all the alimentary principles as they pass out from the
stomach.

Action upon Fats. — Even before the publication of Ber-
nard's researches, it was pretty generally admitted that the
digestion of fat consisted in its minute subdivision and sus-
pension in the form of an emulsion. This view was adopted
from the fact that during the absorption of fats from the
intestinal canal, the lacteals and thoracic duct always contain
innumerable small fatty globules ; but the ideas of physiolo-
gists as to the particular fluid by which the emulsification of
fats is accomplished were not very well settled. The most
generally received opinion, however, was that this was effect-
ed by the bile ; but experiments on this subject were very
contradictory. The observations of Brodie, confirmed by
Mayo,1 seemed to show that ligation of the bile-duct pre-
vented the formation of white chyle ; while the experiments
of Magendie led to a precisely opposite conclusion.2

Eberle, the author of a treatise on digestion published in
1834:,3 who, it will be remembered, prepared an artificial
gastric juice by macerating in water the mucous membrane
of the stomach,4 adopted the same method in preparing an
artificial pancreatic fluid. He made a number of experi-
ments with a fluid prepared by infusing finely divided por-
tions of the pancreas of the ox in pure water. The results
of his experiments with this fluid upon the fats foreshad-
owed the discovery of Bernard, though they cannot justly

1 MAYO, Outlines of Human Physiology, London, 1827, p. 406.

2 MAGENDIE, Precis Elementaire de Physiologic, Paris, 1836, tome ii., p. 118.

3 EBERLE, Physiologie der Verdauung, Wiirtsburg, 1838. Longet and Milne-
Edwards refer to an edition of this work bearing the date 1834. The edition of
1838 is apparently nothing more than a reprint.

4 See page 236.

ACTION UPON FATS. 343

be said to have anticipated it. The following is the experi-
ment described by Eberle : " Artificial pancreatic fluid
was mixed and shaken up with a drop of oil, and presently
assumed the appearance of an emulsion, but after repose
several small oil-drops again presented themselves, which
appeared to have lost little or none of their clearness and
transparency. However, when more oil was added, and the
mixture shaken, receiving the warmth of the hand, it then
became an opaque, yellowish- white fluid, from which, after
repose, considerable oil separated on the surface. But this
oil was itself white and opaque, and so finely subdivided, that
it presented a creamy appearance, and the remaining fluid
did not again become clear.

" Consequently the pancreatic juice is capable of taking
up fat in a very finely subdivided condition and thus forming
a sort of emulsion." 1

The opinion thus advanced by Eberle was a mere conjec-
ture, based upon the behavior of an artificial fluid which had
not been proven to possess the properties of the normal pan-
creatic secretion. Though these passages are quoted by Lon-
get a as proof that Bernard did not discover the function of the
pancreas, it must be acknowledged that they bear no more rela-
tion to the discovery as established by positive demonstration,
than do the sayings of Servetus, Columbo, or Cesalpinus, to
the demonstration of the circulation of the blood by Harvey.
Eberle did not obtain the secretion of the pancreas, and the
emulsion which he formed with his artificial fluid was mani-
festly very imperfect. Furthermore, the experimental basis
for his views was so slight that his observations are not even
mentioned in the works on physiology published at that
time, save in one, where they received merely a passing al-
lusion.3 It is only since the function of the pancreas has been

1 EBERLE, op. cit., p. 251.

3 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 260.
? LONGET (loc. cit.) states that the opinion of Eberle seems to have been
adopted by Burdach. Burdach was the author of a large work on physiology, in

344: DIGESTION.

demonstrated by Bernard, and his observations have been so
widely corroborated that it is now regarded as an established
fact, that- earlier publications on this subject have possessed
any interest or importance.

With the exception of the above-mentioned observations
of Eberle, nothing definite had been ascertained concerning
the digestion of fats anterior to the experiments of Bernard.1

One of the most remarkable facts observed by Bernard
was that, in the rabbit, after the ingestion of fatty matters,
vessels filled with white chyle do not make their appearance

nine volumes, with additions by E. Burdach, Dieffenbach, Mayer, J. Miiller,
Rathke, Siebold, Yalentin, and Wagner. — ( Traite de Physiologic consideree comme
Science d1 Observation, trad, par Jourdan, Paris, 1837-1841.) This work is
mainly a compilation of the physiological literature of the day, drawn largely
from the German. In vol. ix., p. 380, which is referred to by Longet, Burdach
quotes two lines from Eberle, saying that " according to Eberle, it (the pancre-
atic juice) serves besides to dilute the fat, and to reduce it to the form of an
emulsion ; a great part of its constituent principles pass also into the chyle.7'
But in the previous page (379) he has the following paragraph :

" We have even less knowledge of the effects of the pancreatic juice than
of those of the bile. Eberle supposes that it is analogous to the intestinal juice,
because the pancreas is a continuation of the intestine. But, in reasoning in
this manner, one would have fully as much foundation for saying the same thing
of the bile. And when Eberle attributes to it the effects which he has remarked
in the pancreatic juice artificially imitated, by that, he gives a very feeble basis
to his theory, which fortunately contains nothing in particular."

As the above constitutes about the only mention which is made of the obser-
vations of Eberla, even in German works, it is very easy to appreciate the state
of knowledge concerning the function of the pancreas, anterior to the experi-
ments of Bernard ; and it is not surprising that he should have been ignorant
of these experiments, which have been only quoted since his discovery has taken
so prominent a place in science.

1 These experiments were commenced in the winter of 1846, and were first
publicly announced in the year 1848, in a communication to the Society of Biology
of Paris. They were subsequently made the subject of a memoir which received
the prize of the Academy of Sciences, in 1850. A full account of all the researches
of Bernard upon this subject is contained in his Memoire sur le Pancreas, Paris,
1856. The results of his experiments are also contained in his Lecons sur la
Physiologic Experimentalc, Paris, 1856, and in the Lecons surles Proprietes Phy-
swlogiquea et les Alterations Pathologiques des Liquides de V Organisms, Paris,
1859, tomeii.

ACTION UPON FATS. 345

at the commencement of the small intestine, as in other
animals, but are first seen from twelve to twenty inches
below the pylorus. The anatomical peculiarity in these ani-
mals is that the pancreatic duct, instead of opening into the
intestine with the bile-duct at the upper part of the small
intestine, has its opening from twelve or twenty inches be-
low ; just at the point where the chyliferous vessels are ob-
served. This fact, which we have frequently confirmed, points
directly to the pancreatic juice as the agent principally, if not
exclusively, concerned in emulsifying the fats ; while it shows
that the bile possesses little or no immediate efficiency in this
regard.

Following out this line of inquiry, and operating with
fresh, coagulable pancreatic juice and the liquid fats, or
those capable of being liquefied by gentle heat, it was
found that slight agitation of this fluid with the fats pro-
duced a very fine and permanent emulsion, similar in every
respect to the milky fluid found in the lacteals during di-
gestion. In fact, comparative analyses of the lymph and
chyle have shown that the lattei* liquid is nothing more than
lymph, with the addition of fatty emulsion. As soon as the
absorption of fat is completed, the lacteal vessels lose their
opaque white contents, and carry nothing but colorless lymph.
This is one of the great experimental facts upon which is
based the view that the pancreatic juice has the property
of digesting the fats. Concerning the accuracy of this obser-
vation there can be no doubt. The fact has been so fre-
quently confirmed, that it must now be considered as estab-
lished beyond question ; and we can add our testimony to its
accuracy from personal observation. It is true that some of
the German physiologists have been unable to confirm these
experiments ; l but by carefully following out the process in-
dicated by Bernard, which is detailed with great care, we
have invariably found his observations to be correct. It

1 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. i., p. 500
et seq.

34:6 DIGESTION.

is well known that many of the German experimenters op-
erated with pancreatic juice which was not coagulahle, and
which Bernard regards as abnormal and incapable of digest
ing fat. With regard to the observation upon the lacteals of
the rabbit, by following out carefully the directions given by
Bernard, and injecting into the upper part of the intestine of
this animal a small quantity of a solution of fat in ether, we
have seen the lacteals appear just at the orifice of the pan
creatic duct and below it, while they were absent above.1

The pancreatic juice is the only one of the digestive fluid?
which is capable of forming a complete and permanent emul-
sion with fats. The fact that the other digestive fluids will
not accomplish this is easily demonstrated as regards saliva,
gastric juice, and bile. The intestinal juice is then the only
one which might be supposed to have this property. The
observations of Busch on this point, in his case of intestinal
fistula, are conclusive. He found that fatty matters taken
into the stomach were discharged from the upper opening in
the intestine in the form of a fine emulsion, and were never
recognizable as oil ; but that fat introduced into the lower
intestinal opening was not acted upon, and was discharged
unchanged in the faeces.2

Another peculiarity noted by Bernard in the emulsion
resulting from the action of pancreatic juice upon fats is that
it persists when diluted with water, and will pass through a

J It has been shown by Bernard that ether is one of the most powerful ex-
citants of the pancreatic secretion ; and consequently when fat in solution in
ether is introduced into the intestinal canal, the secretion is poured out in abun-
dance, and the fat is immediately emulsified. — (Lemons sur les Effets des Sub-
stances Toxiques et Medicamenteuses, Paris, 1857, pp. 417, 418.)

The observations of Bernard upon rabbits were fully confirmed in a series
of experiments performed under the direction of Prof. Samuel Jackson, of Phila-
delphia. He fed these animals with fat and vegetables in the way indicated
by Bernard, and never saw the lacteals fully injected with chyle above the open-
ing of the pancreatic duct. — (American Journal of the Medical Sciences, October,
1854.)

2 BUSCH, in YIRCHOW'S Archiv, Berlin, 1858, Bd. xiv., S. 165, 175 ; and
American Journal of the Medical Sciences, July, 1860, pp. 219, 220.

ACTION UPON FATS. 34:7

moistened filter like milk. This does not take place in the
imperfect emulsion formed by a mixture of oil with any
other of the digestive fluids.

Although the normal pancreatic juice is constantly al-
kaline, this is not an indispensable condition as regards its
peculiar action upon fats ; for the emulsion is none the less
complete when- the fluid has been previously neutralized
with gastric juice.

Bernard has shown that the pancreatic juice and the tis-
sue of the pancreas have the property of saponifying fats, or
decomposing them into a fatty acid and glycerine, and that
this property is not possessed by any other tissue or liquid
of the economy.1 The question naturally arises, then, whether
this be an accidental property of the tissue and the secretion
of the pancreas, or whether partial saponification of fat takes
place in digestion. Concerning this point there is no dif-
ference of opinion among physiological chemists. The fat
which is contained in the lacteal vessels is always neutral ;
and the absence of any fatty acid has been recognized by
Bernard, as well as by others. The inevitable conclusion to
be drawn from this fact is, that while fat may be in part de-
composed into an acid and glycerine by the pancreatic juice,
out of the body, in the natural process of digestion, either
this does not take place, or the acid is not absorbed by the
lacteals. The greatest part, if not the whole, of the fat
which is digested in the small intestine is simply formed
into an emulsion by the pancreatic juice, and undergoes no
chemical alteration.

To complete the experimental evidence of the action of
the pancreatic juice in the digestion of fats, Bernard at-
tempted to extirpate or destroy the pancreas in a living ani-
mal. This he found very difficult. All attempts to extir-
pate the organ with the knife being unsuccessful, the injec-
tion of foreign matters into the duct was resorted to. After
a great number of unsuccessful experiments, in two in-

1 BERNARD, op. dl., p. 94 et seq.

348 DIGESTION.

stances, the functions of the gland were suspended for a
time, and its tissue was partly destroyed by the injection of
melted tallow. In both of these observations, the effects
upon digestion were very marked. Though the appetite
was voracious, the animals became gradually emaciated,
and the faeces contained a large quantity of rancid undi-
gested fat. At the same time, other alimentary principles,
incompletely digested, were recognized in the discharges. In
two dogs operated upon by Bernard, in which the experi-
ments were successful, the nutrition and the alvine discharges
became normal at the thirteenth and the seventeenth day.

«/

After the animals had completely recovered, they were killed,
and the pancreas in both instances was found partially de-
stroyed.1

I^ow that the action of the pancreatic juice upon fats is
so well understood, it is a matter of surprise that the cases
of fatty diarrhoea connected with disorganization of the pan-
creas, which were reported by Dr. Richard Bright, in 1832,2
did not direct the attention of physiologists to the function
of this organ. These cases, with others of a similar charac-
ter which have been reported from time to time, are now
brought forward as strong evidence of the action of the pan-
creas in the digestion of fats. Many of them presented a
train of symptoms • analogous to those observed in animals
after partial destruction of the gland. The presence of fat
in the alvine dejections was most marked ; and, as is now
well known, this could be nothing but the undigested fatty
principles of the food. In the three cases observed by Bright,
the pancreas was found so disorganized that its secreting
function must have been almost, if not entirely, abolished.

1 BERNARD, Memoire sur le Pancreas, Paris, 1856, pp. 17 and 69.

2 BRIGHT, Cases and Observations connected with Diseases of the Pancreas and
Duodenum. — Medico- Chirurgical Transactions, London, 1833, vol. xviii., p. 1 et
seq. In the same volume (p. 57) is a case of jaundice with discharge- of fatty
matter from the bowels and a contracted state of the duodenum, reported by
E. A. Lloyd, Esq., and still another case of the same character is reported by
Dr. J. Elliotson.

ACTION UPON FATS. 34:9

Iii the case reported by Mr. Lloyd, the condition was the
same ; and in the case reported by Dr. Elliotson, " the pan-
creatic duct and the larger lateral branches were filled with
white calculi." Another interesting case of disease of the
pancreas is detailed in the catalogue of the Anatomical Mu-
seum of the. Boston Society for Medical Improvement, 184/T.
In this case it was observed by the patient that fatty dis-
charges from the bowels did not take place unless fatty ar-
ticles of food had been taken. After death, a large tumor
was found in the situation of the pancreas, but all trace of
the normal structure of the organ had been destroyed.1

Many more cases of this character are quoted by Ber-
nard and others, and they fully confirm the observations and
experiments which have been made upon the lower animals 2
They all seem to show that the function of the pancreas in
digestion is essential to life, but that one of the chief dis-
orders in digestion incident to the destruction of this gland
relates to the digestion of fats.

Taking into consideration all the facts bearing upon this
subject, the conclusion is inevitable that the chief agent in
the digestion of fats is the pancreatic juice ; and that this
fluid acts by forming with the fat a very fine emulsion, thus
reducing it to a form in which it can be absorbed. How far
the bile may assist in this process is a question which will
come up for consideration hereafter ; but the facts with re-
gard to the pancreatic juice are conclusive. In making this
unqualified statement, it is not intended to ignore the experi-
ments of some of the German physiologists, which have

1 A Descriptive Catalogue of the Anatomical Museum of the Boston Society
for Medical Improvement, Boston, 1847, p. 174.

2 Dr. John H. Griscom, of New York, gives the details of an interesting case
of Diarrhoea Adiposa, in the Transactions of the American Medical Association,
1813, volume xiv., p. 173 et seq. In this case, recovery apparently took place,
and the patient passed from observation. He also gives a tabulated analysis of
twenty-five cases of discharge of fatty matter from the bowels observed by
various authors. It is not unusual for cases of this kind to terminate in
recovery.

350 DIGESTION.

seemed opposed to the observations of Bernard.1 To many
of these experiments, reference has already been made. In
endeavoring to ascertain the truth of an important physio-
logical statement supported by experimental facts, it is indis
pensable first to put one's self in the position of the experi
menter, and carefully to repeat his observations in precisely
the way in which they were originally made. Having done
this, we have been able on many occasions to confirm the
most important of the experiments of Bernard ; 2 and we can
find nothing in the contradictory observations of others
which invalidate their accuracy. So long us physiologists
operate with the watery secretion which flows from a per-
manent pancreatic fistula, they will fail to observe the prop-
erties of the normal fluid ; and if they will carefully follow
the experimental procedure so minutely detailed by Bernard,
their observations will be in accordance with the results
at which he has arrived.

Action upon Starchy and Saccharine Principles. — All
physiologists are agreed with regard to the action of the pan-
creatic juice in transforming starch into sugar. This was
first observed, in 1844, by Yalentin, who experimented with
an artificial fluid made by infusing pieces of the pancreas
in water.3 Bouchardat and Sandras first noted this property
in the normal pancreatic secretion. They obtained the se-
cretion in small quantity from the goose, by killing it while

1 FRERICHS, Die Verdauung, in WAGNER'S Handworterbuch der Physiologic,
Braunschweig, Bd. iii. — LENZ, De Adipis Concoctione et Absorptions, Dorpati,
1850. — BIDDER UNO SCHMIDT, Die Verdaungssafie, Leipsig, 1852. — LEHMANN,
Physiological Chemistry, Philadelphia, 1855, vol. i.

2 We have repeatedly confirmed most of the experiments of Bernard show-
ing the action of the pancreatic juice upon fats ; but have not succeeded in
destroying the pancreas in a living animal and noting the effects upon digestion
of the absence of the secretion. "We attempted this a number of times, in 1860,
by injecting the pancreatic duct with fat, but in all of the experiments the ani-
mals died, of peritonitis.

3 VALENTIN, Lehrbuch der Physiologic des Menschen, Braunschweig, 1844, and
second edition, 1847, Bd. i., S. 356.

ACTION UPON STAKCHY AND SACCHAEINE PKINCIPLES. 351

in full digestion and pressing out by the duct all the fluid
which the pancreas contained. They noted also the viscid
character of the secretion and its alkaline reaction.1 All
who have experimented on the pancreatic juice since this
time have confirmed these observations.2

The property of converting starch into sugar is pos-
sessed by several of the digestive fluids. "We have seen that
the starchy elements of food are acted upon by the saliva,
that this action is not necessarily arrested as these principles,
mixed with the saliva, pass into the stomach, and that the
intestinal juice of itself is capable of effecting the transfor-
mation of starch into sugar to a considerable extent. It
therefore becomes an important question to determine pre-
cisely how far the pancreas is actually concerned in the di-
gestion of this class of principles.

Bernard places the pancreatic juice at the head of the list
of the digestive fluids which act upon starch.3 This view is
undoubtedly correct ; though he goes a little too far in claim-
ing that starch is almost exclusively digested by the pancreas.
Bernard's experiments, however, were made chiefly on dogs ;
and these animals do not naturally take starch as food.4 In
man, some of the starchy principles of the food are acted
upon by the saliva, but undoubtedly, most of the starch

1 BOUCHARDAT ET SANDRAS, Des FoncHons du Pancreas et de son Influence
dans la Digestion des Feculenls. — Memoire adresse d V Academic des Sciences, le
14 avril, 1845, — Supplement d PAnnuaire de Ttierapeutiquc, Paris, 1846, p. 148
et seq.

2 Frerichs, Bidder and Schmidt, Bernard, Lehmann, and all to whom we
have referred in connection with the function of the pancreas, are agreed with
regard to its action upon starch.

3 Op. dt., p. 128.

4 Bernard found that in pigeons, the pancreas could be extirpated without
producing immediate death. In a pigeon from which the pancreas had been
removed by tearing the tissue away piecemeal with the forceps, when the animal
commenced to eat, two days after the operation, vegetable cells containing unal-
tered starch were found in abundance in the faeces ; while, in health, the starch
which these cells contained was always dissolved out (Lecons de Physiologic Ex-
perimentale, Paris, 1856, p.

352 DIGESTION.

taken as food is digested in the' small intestine. Though the
intestinal juice is capable of effecting its transformation into
sugar, the experimental evidence is conclusive that in this
it is subordinate to the pancreatic juice, which latter effects
this transformation, at the temperature of the body, with
extraordinary activity. There is no evidence that the bile
has any thing to do with this action ; and, indeed, it is stated
by Lehmann, that starch is not materially affected by the
bile, even after prolonged digestion.1

To sum up the whole process of the digestion of starch,
it may be stated, in general terms, that this principle, when
hydrated, which is the usual condition in w^hich it is taken
into the stomach of the human subject, is slightly acted upon
by the saliva, both in the mouth and after it has passed into
the stomach • when it is taken raw, it is hydrated in the stom-
ach, and usually undergoes no transformation into sugar until
it has passed into the small intestine ; and when it passes out
at the pylorus, mainly by the action of the pancreatic juice
but with the assistance of the intestinal juice, it is trans-
formed into glucose, and in this form is absorbed.

We have already followed out the digestion of sugar as
far as the small intestine.2 Glucose undergoes no change in
the stomach, and is taken directly into the circulation. It is
probable, also, from the experiments of Bouchardat and
Sandras and others, that a small quantity of cane-sugar may
in like manner be taken up by the blood-vessels of the in-
testinal mucous membrane.3 It has been shown that a small
quantity of cane-sugar is transformed into glucose in the
stomach, but, as we noted in treating of stomach-digestion,
the quantity is inconsiderable, and the transformation de-
pends simply upon the presence of a free acid in the gastric
juice.

1 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. i., p. 492.

2 See page 268.

3 BOUCHARDAT ET SANDRAS, De la Digestion des Matieres Feculentcs et Sucrees,
etc. — Supplement d TAnnuaire de Therapeutigue, Paris, 1846, p. 81 et seq.

ACTION UPON STARCHY AND SACCHARINE PRINCIPLES. 353

As most of the saccharine principles of food exist in the
form of cane-sugar, it is the action of the digestive fluids
upon this variety of sugar which possesses the greatest phys-
iological interest. As cane-sugar passes from the stomach
into the duodenum, it is almost instantly transformed into
glucose. This fact has lately received additional confirmation
in the case of intestinal fistula observed by Busch. In this
case, when cane-sugar was introduced in quantity into the
stomach, fasting, the fluid which escaped from the upper end
of the intestine contained a small quantity of glucose, but
never any cane-sugar.1

It now becomes a question whether this transformation
into glucose is effected by the bile, the intestinal juice, or
the pancreatic juice. The pancreatic juice and the intestinal
juice are the two fluids which might be supposed to have this
effect ; as it has been repeatedly demonstrated that the bile
has of itself no direct action upon any of the alimentary
principles.

This point is. settled by the experiments of Busch upon
the lower end of the intestine, in his case of fistula. Matters
introduced into this lower opening came in contact with the
intestinal juice only. He found that cane-sugar, exposed
thus to the action of the intestinal juice, was not converted
into glucose, but a large portion of it was found in the faeces.
These observations also indicate that cane-sugar is not read-
ily absorbed by the intestinal mucous membrane until it has
been transformed into glucose.

Out of the body, the pancreatic juice is capable, if kept
but for a short time in contact with any of the saccharine
principles, of transforming them into lactic acid. Bouchar-
dat and Sandras believed that sugar was always changed
into lactic acid in digestion ; 2 but further experiments have
shown that this is not the case.3 The contents of the small
intestine are sometimes alkaline or neutral, and sometimes

1 Loc, cit. 2 Loc. cit.

3 BERNARD, Memoire sur le Pancreas, Paris, 1856, p. 133.
23

354: DIGESTION.

acid. "When a very large quantity of sugar has been taken,
a part of it may be converted in the intestine into lactic acid,
and this may happen with the sugar which results from the
digestion of starch ; but under ordinary conditions, starch
and cane-sugar are readily changed into glucose and are ab-
sorbed without undergoing further transformation. All the
varieties of sugar after they have been absorbed by the por-
tal vein and carried to the liver, are here transformed into
glucose, the only form under which they can be used in nu-
trition.

Action of the Pancreatic Juice on Nitrogenized Prin-
ciples.— Although Eberle and some other German observers,
particularly Purkinje and Pappenheim, alluded to the action
of an acid infusion of the tissue of the pancreas upon certain
nitrogenized principles, as early as 1834 and 1836, it is only
since the normal pancreatic juice was obtained by Bernard
that any thing definite has been ascertained concerning its
action upon this class of alimentary substances ; 1 and even
now, much remains to be done in this direction.

"We have frequently had occasion to insist upon the great
relative importance of intestinal digestion, and it has been
apparent that in the stomach, the process of disintegration of
food is not final, even as regards many of the nitrogenized
principles, but is rather preparatory to the complete liquefac-
tion of these principles, which takes place in the small intes-
tine. The experiments, already referred to, of Bernard, in
which the pancreas has been partly destroyed in dogs, show

1 The ideas of the German physiologists concerning the functions of the pan-
creas were very indefinite before the publication of Bernard's experiments. The
vague and uncertain observations of Eberle and of Purkinje and Pappenheim are
simply alluded to in some of their most elaborate works upon physiology (see
BURDACH, Traite de Physiologic, trad, par Jourdau, Paris, 1841, tome ix., p.
317). These observations by no means justify the claim made by Corvisart that
the authors referred to discovered the action of the pancreatic juice upon the
albuminoids (CORVISART, Sur-une Fonction pen connue du Pancreas, Paris, 1857
-1858, p. 1).

ACTION ON NITROGENIZED PRINCIPLES. 355

rapid emaciation, with great voracity, and the passage, not
only of unchanged fats and starch, but of undigested nitro-
genized matter in the dejections. In some instances, pieces
of tripe which had been fed to the animal were recognizable
in the faeces " by their aspect, because of their slight altera-
tion." * The voracious appetite, progressive emaciation, and
the passage of all classes of alimentary substances in the
fseces, after this operation, demonstrate conclusively the great
importance of the pancreatic juice in digestion. But when
we inquire into the precise mode of action of this fluid upon
the albuminoids, the question becomes one of great difficulty.
If the bile be shut off from the intestine and discharged ex-
ternally by a fistulous opening, the same voracity and ema-
ciation are observed ; and yet there is no single alimentary
substance upon which the bile, of itself, can be shown to
exert a decided digestive action. Furthermore, the pancre-
atic juice is evidently calculated to act upon alimentary prin-
ciples after they have been subjected to the action of the
stomach, a preparation which is absolutely essential to proper
intestinal digestion ; and once passed into the intestine, the
food comes in contact with a mixture of pancreatic juice, in-
testinal juice, and bile. We have to study, therefore, the
special action of the pancreatic secretion upon the albumi-
noids, as far as it can be isolated, and its action in conjunc-
tion with the other intestinal fluids, and in the presence of
other alimentary principles in process of digestion.

The first definite observations upon these points were
made by Bernard. He found that the albuminoid substances
generally, exposed to the action of the pancreatic juice out
of the body, became rapidly softened and dissolved in some
of their parts, but soon passed to a condition of putrefaction.
An analogous change, it will be remembered, also takes place
in starchy and fatty matters when exposed to the action of
the pancreatic juice out of the body, and they pass through
the various stages of transformation respectively into lactic

1 BERNARD, Memoir e snr Ic Pancreas, Paris, 1856, p. 137.

356 DIGESTION.

acid and the fatty acids. This putrefactive action does not
take place in albuminoids which have been precipitated
after having been cooked, nor in raw gluten or caseine.
The presence of fat also interferes with putrefaction; so
that Bernard concludes that the fats have an important
influence in the intestinal digestion of nitrogenized princi-
ples.1 The observations of Corvisart, who experimented,
however, with an artificial fluid formed by infusing the fresh
pancreas in water, were made in order to prove the great
activity of the pancreatic juice in the digestion of albuminoid
substances. Though these experiments are frequently re-
ferred to as throwing considerable light upon a function of
the pancreas but little known, the author of them does not
seem, in their execution, to have fulfilled the necessary phy-
siological conditions ; and his results cannot, therefore, be
accepted as definite and conclusive.2

Taking into consideration what has been positively ascer-
tained concerning the action of the pancreatic juice upon the

1 Op. cit., pp. 129 and 130.

2 CORVISART, Sur une Fonctionpeu connue du Pancreas, Paris, 185 7-1 858, and
Collection de Memoir es sur une Fonctionpeu connue du Pancreas, Paris, 1857-
1863. In the experiments upon the digestion of albuminoids in the duodenum
of a living animal, the intestine was exposed, the duodenum washed out with a
stream of tepid water, and albumen or some other substance introduced ; the duo-
denum being isolated from the rest of the intestine by two ligatures. That normal
digestion and absorption can take place under these conditions is not conceivable.
Again, in experimenting upon the action of the pancreatic juice out of the body,
the pancreatic secretion is never used, but an infusion of the tissue of the gland
is substituted. Though something may be learned by experimenting in this way,
results thus obtained should be compared with those which are obtained by using
the actual secretion of the gland. By using all the precautions recommended
by Corvisart in a paper published in reply to certain objections made to his ex-
periments, by Dr. Brinton (Journal de la Physiologic, Paris, 1860, tome iii., p.
473 et seq.\ we have never been able to manufacture a pancreatic juice with
which we could demonstrate to a medical class the characteristic properties of
the normal secretion. Corvisart does not seem to have verified any of his obser-
vations by operating with the actual secretion of the pancreas ; and, on the other
hand, has written several memoirs to show that infusions of the tissue of glands
resemble the natural secretions more closely than the fluids obtained from their
ducts.

STJMMABY. 357

albuminoids, there can be no doubt with regard to the impor-
tance of its function in. the digestion of these principles after
they have been exposed to the action of the gastric juice.
The experiments of Bernard and the later observations of
Daltpn upon the digestion of these substances after they have
passed out of the stomach show that they undergo impor-
tant and essential changes as they pass down the intestinal
canal. While the bile and the intestinal juice are by no
means inert, they seem to be only auxiliary in their action to
the pancreatic juice. When meat is taken into the stomach,
or is exposed even for a long period to the action of the gas-
tric juice, there is always more or less insoluble residue,
which can be shown by microscopical examination to consist
of the muscular substance. Dalton has shown, in a carefully
conducted series of observations, that the characteristic strise
gradually disappear and the tissue is dissolved as it passes
down the intestine ; * and although he entertains the view
that this is due to the action of the gastric juice which is
continued in the intestine, the evidence derived from the
observations of others seems to show that it depends mainly
upon the pancreatic juice.

The preparation which the albuminoids undergo in the
stomach is undoubtedly necessary to the easy digestion, in
the small intestine, of that portion which is not dissolved by
the gastric juice. This fact has been conclusively demon-
strated by experiments on intestinal digestion in the inferior
animals, and by the observations of Busch in the case of in-
testinal fistula in the human subject.

Summary. — The action of the pancreas upon the various
articles of food may be summed up in a few words :

This fluid is the only one capable of forming an instanta-
neous, complete, and permanent emulsion with the liquid
fats, thus preparing them for absorption by the lacteals. The
fat from the adipose tissue is set free in the stomach and

1 DALTON, Treatise on Human Physiology, Philadelphia, 1864, p. 157 et seq.

358 DIGESTION.

liquefied, but is not otherwise acted upon. In normal diges-
tion, the pancreatic juice does not acidify fats.

Raw starch — which becomes hydrated in the stomach —
and cooked starch are changed. into sugar by the pancreatic
juice, and in this form are absorbed. In this the pancreatic
secretion is aided by the intestinal juice, a fluid which pos-
sesses the same property, though in a less degree. Cane-
sugar and milk-sugar are probably changed into glucose by
the pancreatic juice alone. This change takes place to a very
slight extent in the stomach.

The albuminoids, such as gluten, fibrin, albumen, caseine,
and musculine, which have been disintegrated but not dis-
solved by the gastric juice as they pass out of the stomach, are
liquefied by the pancreatic juice with the aid of the bile and
the intestinal juice, are changed into albuminose, or peptones,
and are thus absorbed. This takes place whether the reac-
tion of the contents of the intestine be alkaline, acid, or neu-
tral. Though the action of the pancreatic juice, out of the
body, soon induces putrefaction in many of the albuminoids,
this does not occur in the natural process of digestion. The
presence of a small quantity of fat retards this putrefactive
change in artificial digestion, and it may have some influence
upon the digestion of these principles in the intestine. '

As the different articles pass out at the pylorus, in the
natural process of digestion, they are in the condition most
favorable for the action of the intestinal fluids. The starch
is always hydrated, with the particles separated and distrib-
uted through the entire mass of food ; the oil is freed from
the vesicles in which it is enclosed in the adipose tissue, and
is likewise distributed through the alimentary mass ; the ni-
trogenized articles are disintegrated, softened, and reduced to
a pultaceous mass ; and, in fine, all the food which has not
been digested in the stomach is prepared to absorb with
avidity the fluids which it meets in the intestine, so that it
rapidly undergoes the final changes which take place in this
part of the digestive apparatus. Again, the food is passed

STJMMAKY. 359

out very gradually, and only after it has been fully prepared
in the stomach for intestinal digestion.

In intestinal digestion, all the secretions found in the
small intestine combine to accomplish the final result ; and
it only remains for us to examine how far and in what way
this process is influenced by the bile.

CHAPTEE XIII.

ACTION OF THE BILE IN DIGESTION MOVEMENTS OF THE SMALL

INTESTINE.

Question of the excrementitious or recrementitious character of the bile — Liga-
tion of the ductus communis choledicus — Biliary fistula — General constitu-
tion of the bile — Observations on a dog with biliary fistula — Variations of the
bile with digestion — Movements of the small intestine — Peristaltic and anti-
peristaltic movements — Cause of the movements of the small intestine —
Function of the gases in the small intestine — Peristaltic movements after
death — Influence of the nervous system upon the peristaltic movements.

Action of tJie Bile in Digestion.

A GKEAT deal of diversity of opinion has existed among
physiologists concerning the functions of the*bile. It is now
pretty generally acknowledged that this fluid has, of itself,
no marked influence upon any of the different classes of ali-
mentary principles, such as we have observed in the other se-
cretions which are discharged into the alimentary canal. This
being the case, it is important to decide whether the bile is
essential in assisting or modifying the action of other secre-
tions, or whether it is entirely inert in the digestive process.
From the fact that it is poured into the upper part of the
small intestine, it would seem that it must have some office,
either in modifying the digestion and absorption of food, or
in the passage of alimentary substances or their residue down
the intestinal tract. It is difficult to suppose that a fluid
which is brought in contact with the alimentary mass in that
portion of the intestine where the most important digestive
processes commence should be simply excrementitious ; yet

ACTION OF THE BILE IN DIGESTION. 361

this is the view entertained by some experimentalists, more
especially Blondlot. In this position of the subject, natu-
rally the first question to decide is concerning the excremen-
titious or recrementitious character of the bile ; or whether,
in other words, it is separated from the blood simply to be
discharged from the body, or has some important function to
perform as a secretion.

An apparently simple method of settling this question
has been employed by many experimenters, but with results
which are not satisfactory unless they can be in some way
harmonized. Schwann, Nasse, Bidder and Schmidt, and
Bernard, whose observations will be more fully considered
hereafter, have performed experiments upon animals in
which the bile was entirely shut off from the intestine and
discharged from the body by a fistula. If the bile be simply
excrementitious, it should follow that animals operated upon
in this way would not suffer from the discharge of the bile
by a fistula and its diversion from the intestine ; but in all
of them, death occurred with symptoms pointing to defective
nutrition consequent upon grave disorder of digestion. The
same result followed our own experiments on this subject.
On the other hand, Blondlot attempts to show that the bile
is simply an excretion, and that animals thrive and will live
for an indefinite period when it, is diverted from its natural
course and discharged from the body.

In the experiments of Blundell, Brodie, and others, who
simply closed the ductus communis choledicus, the effects of
shutting off the bile from the intestine were modified by the
consequent undue accumulation of this fluid in the biliary
passages. The only way to obviate this difficulty was to dis-
charge the bile by a fistula, as was first done by Schwann.
The first experiments reported by Schwann were made upon
sixteen dogs and one rabbit. Of these, only six can be re-
garded as successful ; and in the others, the animals either
died of peritonitis resulting from the operation, or recovered,
the fistulous opening into the gall-bladder becoming closed

362 DIGESTION.

and the communication between the liver and the intestine
reestablishing itself. These six animals died, apparently
of inanition, respectively, after seven, thirteen, seventeen,
twenty-five, sixty-fonr, and eighty days. In all, except the
t\vo animals that lived for sixty-four and eighty days, respec-
tively, there was gradual diminution in weight from the date
of the operation, notwithstanding that a large quantity of food
was taken. In the two exceptions, there was first diminution
in weight, then the flesh was partially regained, but it sub-
sequently diminished until death occurred.1 In these six ani-
mals there was every reason to believe that death occurred
from the loss of the digestive function of the bile, and the dis-
turbances in nutrition wrere very much like those produced by
Bernard by destruction of the pancreas. These experiments
were confirmed in their essential particulars by Bidder and
Schmidt, Nasse, and Bernard. In an observation reported by
Bernard, the animal died two months after the operation,
having presented gradual emaciation accompanied by great
voracity.2

These facts seem to show that the bile is not simply an
excrementitious fluid, and that its function, after it is dis-
charged into the intestine, is not only important, but abso-
lutely essential to life. The only experiment which is op-
posed to this view is one reported by Blondlot.

The experiment by Blondlot was made upon a dog. The
fistula was established in the fundus of the gall-bladder,
the ductus communis having been tied and a portion ex-
sected, after the method employed by Schwann. Fifteen
days after the operation, the animal had become extremely
thin, but ate well, and, according to the report of the experi-
menter, was in perfect health. During all this time, how-

1 SCHWANN, Experiences pour constater si la JBile joue dans I1 Economic Ani-
male un Role essentiel pour la Vie. — Memoire lu d la Seance de V Academic Royah
du 6 juillet, 1844. — Nouveaux Memoircs de V Academic Royale des Sciences et Belles-
lettres de Bruxclles, Bruxelles, 1846, tome xviii.

2 BERNARD, Liquides de VOrganismc, Paris, 1859, tome ii., p. 199.

ACTION OF THE BILE IN DIGESTION. 363

ever, lie habitually licked the bile, but was finally prevented
from doing this by a muzzle. From the moment when the
dog ceased to swallow the bile, the nutrition began to im-
prove, and in three months he had recovered the natural
amount of flesh.1 A further account of this experiment is
given by Blondlot in another memoir.2 The animal, while
in perfect health, aside from the existence of the fistula, was
claimed by the owner, from whom it had been stolen before
it passed into the hands of the experimenter. With the fistula
still open, the dog was used by its owner for hunting and lived
for five years. At the end of this time it was returned to H.
Blondlot, but died while in his possession, two months after.

The important question then to determine was that the
bile had been completely shut off from the intestinal canal.
An examination of the parts was consequently made, in the
presence of a number of physicians and students. On the
most minute dissection, it was impossible to find any com-
munication between the bile-duct and the duodenum ; and
the conclusion arrived at was that the animal had lived for
five years without a drop of bile passing into the intestine,
and, consequently, that this fluid was useless in digestion.

The facts obtained by all other observers are in direct op-
position to the above experiment. After a number of trials,
we succeeded in establishing a biliary fistula in a dog, the
operation being followed by no inflammation of the peri-
toneum, and notwithstanding that the animal was voracious
and consumed daily large quantities of food, it died in thirty-
eight days, of inanition.3 If our own observation and those
of other experimenters be correct, it is impossible that an ani-

1 BLONDLOT, Essai sur les Fonciions du Foie et de ses Annexes, Paris, 184-6, p.
55 et seq.

3 BLOXDLOT, Inutilite de la Bile dans la Digestion proprement dile, memoire
complementaire de V Essai sur les Fonctions du Foie, Paris, 1851.

3 Experimental Researches into a neio Excretory Function of the .Liver. —
American Journal of the Medical Sciences, October, 1862. The details of this ex-
periment will be given further on, when we come to treat of the actual function
of the bile in digestion.

364 DIGESTION.

mal should live in perfect health for years with all the bile
discharged by a fistula.

There is reason to believe that the experiment of Blond-
lot was inaccurate, and that a communication existed between
the bile-duct and the duodenum, which was not discovered
at the dissection after death. The following observation
strengthens us in this opinion :

We made an attempt on one occasion to ascertain the
total amount of bile secreted in twenty-four hours ; and with
this view, the ductus comrnunis choledicus was exposed in a
dog ; the bile contained in the gall-bladder was pressed out ; a
canula, with an elastic bag attached, was fixed in the duct ;
and the external wound closed, leaving the end of the canula,
with the bag attached, protruding from the abdomen. The
bag ruptured twenty-three hours after, and the experiment
was consequently unsuccessful in the end for which it was
undertaken. The tube dropped out at the end of forty-eight
hours, and the external wound quickly healed. Thirty days
after the operation, the animal was killed. He had then en-
tirely recovered, and no bile had been discharged externally
for a long time. The alvine dejections were perfectly nor-
mal, and there could be no doubt that the bile was regularly
discharged into the duodenum. On dissection after death,
the liver was found normal, and the papilla which marks
the opening of the bile-duct into the duodenum was natural
in appearance. It was with the greatest difficulty, however,
that the communication between the bile-duct and the duo-
denum could be found ; yet, after patient searching for more
than an hour, a small tortuous tract was discovered. Had
it not been certain that bile had been constantly discharged
into the intestine, it might have been assumed, even after
careful examination, that no such communication existed.1
This examination convinced us that it was possible that the
communication between the duct and the intestine had been

I0p.cit.) — American Journal of the Medical Sciences, October, 1862.

ACTION OF THE BILE IN DIGESTION. 365

reestablished in Blondlot's case, and that it had escaped ob-
servation in the dissection after death.

One point in the observations of Blondlot which makes it
evident that all the bile was not discharged by the fistula is
the repeated statement that the animal was perfectly well,
and no one would know from its appearance that it had a
fistula. In our own experiment, the lower part of the abdo-
men and the legs were covered with a thick coating of in-
crusted bile, and it was impossible to keep the parts clean.
This must take place if all the bile be discharged by a fis-
tula, and could hardly fail to attract the attention of every
one.

The isolated experiment of Blondlot does not therefore
invalidate the results obtained by Schwann and confirmed
by so many eminent physiologists. The bile is not simply
an excretion, but has an important and essential office to
perform in the process of intestinal digestion. "We have,
however, conclusively shown that, in addition to its recremen-
titious function, it separates from the blood an important ex-
crementitious principle, cholesterine, which, under a modified
form, is discharged in the faeces.1 This function of the liver
will be fully considered under the head of excretion. It is
sufficient for our present purposes to show that the bile, un-
like any other fluid in the organism, has two distinct func-
tion's, dependent upon two distinct classes of constituents.
The peculiar principles known as the biliary salts, which are
produced first in the liver, give it its digestive properties ; and
the cholesterine, which is simply separated from the blood by
the liver, gives it its excrementitious character.

As we are much better acquainted with the excrementi-
tious than with the digestive function of the bile, we will
only consider, in this connection, a few of the points concern-

1 See an article by the author, entitled Experimental Researches into a New
Excretory Function of the Liver; consisting in the removal of Cholesterine from
the Blood, and its discharge from the Body in the form of Slercorine (the Serolint
of Boudet}. — American Journal of the Medical Sciences, October, 1862.

366 DIGESTION.

ing the chemistry of this fluid ; deferring a full account of its
composition until we come to treat of it as an excretion.

The bile varies in color and consistence in different ani-
mals. It usually has a greenish, yellowish, or brownish hue.
In the human subject, it has a dark golden-brown color,
and is somewhat viscid in consistence, chiefly from ad-
mixture with the mucus of the gall-bladder. The specific
gravity of human bile has been found to be about 1,018.' Its
reaction is faintly alkaline.

Physiological chemists have long since recognized in the
bi]e peculiar principles, which are found in no other part of
the organism ; but the exact nature of these constituents was
first described by Strecker, in 1848. The principle described
by Eerzelius under the name of biliary matter, subsequently
separated by Thenard into two principles, called by him bil-
iary resin and picromel, and afterward treated of by Tiede-
mann and Gmelin, who obtained two substances, which they
called taurine and cholic acid, was analyzed by Strecker, who
obtained from the bile of the ox two acids, cholic and cho-
leic acid, which he found existed in this fluid in combina-
tion with soda.2 The results of these researches by Strecker
into the chemistry of the bile, the most extended and accu-
rate which had ever been made, are now generally accepted
by physiologists. The cholic acid of Strecker, which may
be decomposed into a new acid and a principle called glycine,
and the choleic acid from which may be formed a new acid
and taurine, are called by Lehmann, respectively, glycocholic
and taurocholic acid.3 In the bile of the ox, these are found
combined with soda, and the peculiar proximate principles
of this fluid are now recognized as the glycocholate of soda, a

1 DALTON, Human Physiology, Philadelphia, 1864, p. 175.

2 STRECKER, Untersuchung der Ochsgalle. — Annalen der Chimie rind PJiarma-
cie, Heidelberg, 1848, Bd. Ixv. S. 1 et scq. ; and Bd. Ixvii., S. 1 el seq. ; Beobach-
lungen uber die Galle verschiedener Thiere, Idem, 1849, Bd. Ixx., S. 149 et seq,
An analysis of the above is given in the Journal de Pharmacie ft de Chimie,
Paris, 1848, tome xiii., p. 215 ; 1849, tome xv., p. 153 ; and tome xvi., p. 450.

3 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. ii.,p. 201 et seq.

ACTION OF THE BILE IN DIGESTION. 367

. crystalline substance, and the taurocholate of soda, which is
of a resinous consistence, and is stated to be uncrystallizable.

The whole subject of the constitution of the bile has
been admirably reviewed by Dalton, who has made, in addi-
tion, important original researches into the constitution and
physiology of this fluid.1 In the human bile, Dalton has
found a resinous substance, which, from its behavior with
various reagents, is undoubtedly analogous to the taurocho-
late of soda of ox-bile, but which he could not obtain in a
crystalline form.3

In addition to the biliary salts, the bile contains the ordi-
nary inorganic salts, found in nearly all the animal fluids, a
small quantity of fat, the oleates, margarates, and stearates
of soda and potassa, mucus from the gall-bladder, and cho-
lesterine ; the last being an excrementitious product. The
action of the bile in digestion, whatever its nature may be,
undoubtedly depends chiefly upon the biliary salts, and per-
haps to some extent upon its saponaceous constituents.

Experiments on the action of the bile upon different ali-
mentary substances out of the body have not led to any defi-
nite results. It is only in connection with the other diges-
tive fluids that it seems to be efficient ; and the only obser-
vations which have thrown any light upon, the subject are
those made upon digestion in the living organism. Simple
ligation of the bile-duct, as was practised by Blundell, Bro-
die, Magendie, Mayo, and others, has taught us very little
regarding the effects of shutting off the bile from the intes-
tine ; for the immediate effects of the operation generally
interfered with the process of digestion, and subsequently the
experiment was necessarily disturbed by the effects of the
retention of bile in the excretory passages. As would nat-

1 DALTON, On the Constitution and Physiology of the JBile. — American Journal
of the Medical Sciences, October, 1857.

* Since writing the above, we have been informed bj Professor Dalton that ho
has succeeded in obtaining a small quantity of crystalline matter from the human
bile.

368 DIGESTION.

urally.be expected, these observations have been quite con-
tradictory. Brodie found no white chyle in the lacteals
after the duct had been tied,1 while Magendie, in two simi-
lar experiments, found that the chyle was formed without
the aid of the bile.2 Of others who have repeated these ex-
periments, some have confirmed the observations of Brodie,
and some, those of Magendie.

The results of experiments upon the digestive function
of the bile have not been very definite ; but those which have
been most satisfactory have followed the establishment of a
fistulous opening into the gall-bladder, the flow of bile at
the same time being completely shut off from the intestine.
In all experiments of this kind in which fatal inflammation
did not follow the operation, death has taken place from inan-
ition, notwithstanding an increase in the quantity of food
taken. Schwann has shown that this result is not due simply
to the loss of the solid matter discharged in the bile, which is
small in proportion to the total daily loss of weight.3 It un-
doubtedly proceeds from disordered nutrition, which has its
starting point in disordered digestion.

We have now to study the modifications in digestion and
nutrition which are the result of simply diverting the bile
from the intestine. With that view we followed carefully
these changes in the animal with a biliary fistula, that was
under our own observation. This experiment confirmed, in
all important particulars, those of Schwann and of Bidder
and Schmidt. It is given here somewhat in detail, for inas-
much as no inflammation followed the operation and noth-
ing occurred to complicate the effects of the diversion of the
bile from the intestine, we regarded the experiment as re-
markably successful.

1 BRODIE, Experiences sur V Usage de la Bile dans la Digestion. — Journal de
Physiologic, Paris, 1 823, tome iii., p. 93.

2 MAGENDIE, Precis Elementaire de Physiologic, Paris, 1836, tome ii., p. 118.

3 Loc. cit.

OBSERVATIONS ON A DOG WITH BILIARY FISTULA. 369

Observations on a Dog with Biliary Fistula. — Novem-
ber 15, 1861, a biliary fistula was established in a young
cur-dog weighing twelve pounds. The abdominal organs
were very little exposed, and the experiment, from the first,
promised to be very satisfactory. The bile-duct was first
ligated next the intestine and at its junction with the cystic
duct, and the intermediate portion exsected. The incision
in the abdomen was in the median line just below the ensi-
form cartilage, and was about three inches long. The fun-
dus of the gall-bladder was then drawn to the upper portion
of the wound, and the bile was evacuated by a small open-
ing, the edges of which were attached to the abdominal pa-
rietes. The wound in the abdomen was then closed, except
the opening into the gall-bladder, into which a few shreds of
lamp-wicking were introduced.

The animal appeared to do perfectly well after the opera-
tion, and ate the usual quantity the next day. He was kept
in a warm room, though the weather was mild ; and a care-
ful record was made of his condition every day. The fistula
occasionally showed a tendency to close, but it was kept
open by the occasional introduction of a glass rod. From
time to time, while the animal was under observation, he
licked the bile as it flowed from the fistula. This was finally
prevented by a long wire-muzzle, the sides of which were
covered with oil-silk.

The abdomen was somewhat tumid, with some rumbling
in the bowels, for five days after the operation. The first
alvine discharge took place on the evening of the second day.
The fseces seemed in all regards normal. After that time,
they became very infrequent, though the animal ate well
every day. The fseces that were passed after the third day
were of a grayish color and moderately soft. They had an
exceedingly offensive and penetrating odor. At about
the fifteenth day, the faeces became more frequent; and
from that time were passed three or four times a day. Gen-
erally they were clay-colored ; but on one or two occasions
24

370 DIGESTION.

were quite dark. They always had a peculiarly offensive
odor.

The weight of the animal remained stationary for about
four days. On the sixth day (November 20th) the weight
began to diminish. He weighed on that day, before feeding,
eleven and one quarter pounds. November 22d, he weighed
but little over eleven pounds. November 24th, he weighed
ten pounds. He maintained this weight until December 1st,
when the weight again began to diminish. On December 6th,
the weight was nine pounds. On December 7th, the weight
was reduced to eight and a half pounds, and the strength be-
gan to fail manifestly. December 10th and llth, he gained
a little, on those days weighing nine pounds ; but after that,
he progressively diminished in strength and in weight until
death occurred, thirty-eight days after the operation. The
weight was then seven and a half pounds, showing a total
loss of four and a half pounds, or 37| per cent

During the first nine days of the observation the animal
ate well, but not ravenously, taking about three-quarters of
a pound of beef-heart daily. On the tenth day the appetite
increased. He ate on that day, at one time a pound, and at
another, half a pound of meat. He ate on an average about
a pound and a half of beef-heart daily, until the day before
his death. During the last five or six days he seemed very
ravenous, and was not allowed to eat all that he would at
one time. At this time he was ordinarily fed twice a day.
He would not eat fat, even when very hungry. During the
last day, when too weak to stand, he attempted to eat while
lying down. During the last twelve days of the observation,
he attempted constantly to eat the faeces.

During the last days of the experiment, when the dog
had become much reduced in weight, he became very cross,
and snapped at every animal that came near him. There
was never any icterus, fetor of the breath, or falling off of
the hair.

A careful examination of the animal was made after

OBSERVATIONS OX A DOG WITH BILIARY FISTULA. 371

death. The gall-bladder was somewhat contracted but not
obliterated, and the fistula would admit the largest-sized
male catheter. Both ends of the divided bile-duct were
found impervious. There was no passage for the bile into
the intestine. The abdominal organs were normal, with the
exception of evidences of slight peritoneal inflammation
around the wound and over the convex surface of the liver.
There was no fat in the omentum or anywhere in the body,
except a very small quantity at the bottom of the orbit.

The above observation is a type of the instances — which
are not very numerous — in which the bile has been complete-
ly shut off from the intestine and discharged externally by a
fistula into the gall-bladder. As far as could be ascertained,
this animal, from the first, presented no disturbances which
were not due solely to the absence of the bile from the intes-
tine, and its discharge externally. Though the phenomena
here presented do not teach us much that is definite concern-
ing the digestive action of the bile, taken in connection with
what has been ascertained concerning the general properties
of this secretion, they throw some light upon its function.

One of the functions which has been ascribed to the bile
is that of regulating the peristaltic movements .of the small
intestine, and of preventing putrefactive changes in the in-
testinal contents and the abnormal development of gas. Ex-
periments on this point are somewhat conflicting. Our own
observations would lead us to doubt the constant influence of
the bile upon the peristaltic movements. During the first
few days of the experiment, the dejections were very rare ;
but they afterward became regular, and at one time, even,
there was a tendency to diarrhoea. There can be no doubt,
however, that the bile retards the putrefaction of the con-
tents of the intestinal canal, particularly when animal food
has been taken. The faeces in the dog, as far as our own
observation goes, were always extremely offensive. Bidder
and Schmidt found this to be the case in dogs fed entirely
on meat ; but the faeces were nearly odorless when the ani-

372 DIGESTION.

mals were fed on bread alone.1 In the case of intestinal
fistula in the human subject, the evacuations which took
place after the introduction of alimentary substances into
the lower portion of the intestine had an unnaturally offen-
sive and putrid odor. In this case, as it was impossible for
matters to pass from the portions of the intestine above the
fistula to those below, the food introduced into the lower
opening was completely removed from the action of the
bile.

So far as the digestion of the different alimentary princi-
ples is concerned, it has been shown that the bile, of itself,
has no particular action upon any of them. In the faeces
of animals with biliary fistula, the only peculiarity which has
been observed, aside from the putrefactive odor and the
absence of the coloring matter of the bile, has been the pres-
ence of an abnormal proportion of fat. We have observed
this in the faeces of a patient suffering under jaundice appar-
ently due to temporary obstruction of the bile-duct.2 This
fact was noted in the dogs experimented upon by Bidder
and Schmidt.

The various experiments which have been performed upon
animals render it almost certain that the bile has an impor-
tant influence, either upon the digestion or the absorption of
fats. The observations of Brodie and others, in which the
bile-duct was simply ligated, are not very conclusive, as the
disturbances produced by the retention of the bile probably
had an influence upon digestion and absorption ; but Bidder
and Schmidt noted in animals with biliary fistula that the
chyle contained very much less fat than in health. In an
animal with a fistula, and the bile-duct obliterated, the pro-
portion of fat was 1*90 parts to 1,000 parts of chyle ; while

1 Op. cit., p. 218.

2 American Journal of the Medical Sciences, October, 1862. We obtained
from 941*4 grains of faeces taken from this patient, a cake of soap weighing thir-
ty-four grains. In an analysis of the faeces made nineteen days after, when the
patient had recovered, no saponifiable fat was found.

OBSERVATIONS ON A DOG- WITH BILIARY FISTULA. 373

in an animal with the biliary passages intact, the proportion
was 32-79 parts per 1,000.*

In animals operated upon in this way, there is frequently
a great distaste for fatty articles of food. In our own obser-
vation, the dog refused fat meat even when very hungry and
when lean meat was taken with great avidity.

Experiments concerning the influence of the bile upon the
absorption of fats have resulted in hardly any thing definite.
We only know the fact that when the bile is diverted from
the intestine, the proportion of fat in the chyle is greatly
reduced, and a large proportion of the fat taken with the
food passes through the intestine and is found in the -faeces.

The action of the bile in exciting muscular contraction,
particularly in the smooth muscular fibres, is pretty well es-
tablished. It has been shown by Schiff that this fluid acts
upon the muscular fibres situated in the substance of the in-
testinal villi, causing them to contract, and, according to his
view, assisting in the absorption of chyle by emptying the
lacteals of the villi.3 The whole subject, however, of the
absorption of fats is exceedingly difficult of investigation ;
and our knowledge of it has not been sensibly advanced by
the experiments upon the influence exerted by the bile.

Notwithstanding the obscurity in which this subject is
involved, it is certain that the progressive emaciation, loss
of strength, and final death of animals deprived of the
action of the bile in the intestine is due to defective diges-
tion and assimilation. In spite of the great quantities of
food taken by these animals, the phenomena which precede
the fatal result are simply those of starvation. It may be
that the biliary salts are absorbed by the blood and are
necessary to proper assimilation; but there is no experi-
mental basis for this supposition, and it is impossible to dis-
cover these salts in the blood of the portal system by the or-
dinary tests. It is more probable that the biliary salts influ-

1 Op. cit.y p. 227.

2 LOXGET, Traite de Physiologic, Paris, 18G1, tome i., p. 256.

374 DIGESTION.

ence in some way the digestive process and are modified and
absorbed with the food.

The observations of Bidder and Schmidt show conclu-
sively that the characteristic constituents of the bile are
absorbed in their passage down the alimentary canal. Hav-
ing arrived at a pretty close estimate of the quantity of bile
daily produced in dogs, they collected and analyzed all the
faecal matter passed by a dog in five days. Of the dry residue
of the faeces, the proportion which could by any possibility
represent the biliary matters did not amount to one-fourth
of the dry residue of the bile which must have been secreted
in that time. They also estimated the total quantity of sul-
phur contained in the faeces, and found that the entire quan-
tity was hardly one-eighth of that which was discharged into
the intestine in the bile ; and inasmuch as nearly one-half of
that found in the faeces came from hairs which had been
swallowed by the animal, the experiment showed that nearly
all the sulphur contained in the non-crystallizable element of
the bile (the taurocholate of soda) had been taken up again
by the blood.1 These observations show conclusively that
the greater part of the bile, with the biliary salts, is ab-
sorbed by the intestinal mucous membrane. Prof. Dalton
has attempted to follow these principles into the blood of the
portal system, but has never been able to detect the biliary
salts, by the most careful analysis.2 Like the peculiar prin-
ciples of other secretions which are reabsorbed in the aliment-
ary canal, these substances become changed and are not to
be recognized by the ordinary tests, after they are taken into
the blood.

Although it is the digestion and absorption of fatty sub-
stances which seem to be most seriously interfered with in
cases of biliary fistula in the inferior animals, the rapid loss
of weight and strength would indicate great disturbance in

1 BIDDER UND SCHMIDT, Die Verdauungssafte, Leipzig, 1852, S. 217, 218.

2 DALTON, Treatise on Human Physiology, Philadelphia, 1864, pp. 179 and
198.

OBSERVATIONS JDN A DOG WITH BILIARY FISTULA. 37$

the digestion and absorption of other articles of food. A
fact which indicates a connection between the bile and the
process of digestion is that the flow of this secretion, though
constant, is greatly increased when food passes into the intes-
tinal canal. This has been noted by all who have experi-
mented on the subject. The following observations on a
dog, showing the variations in the flow of bile from the fistu-
la, were made twelve days after the fistula had been estab-
lished, when the weight of the animal had been reduced from
twelve to ten pounds :

Table of Variations in the Flow of Bile with Digestion.1

(At each observation, the bile was drawn for precisely thirty minutes.)

TIME AFTER FEEDING.

Fresh Bile.

Dried Bile.

Percentage of Dry Eesidue.

Immediately

Grains.

8-103

Grains.

0-370

4-566

One hour . .

20-527

0-586

2-854

35*760

1-080

3-023

Four hours

38-939

1-404

3-605

22-209

0-987

4-450

Ei^ht hours. ... ...

36-577

1-327

3-628

24-447

0-833

3-407

Twelve hours. .

5-710

0-247

4-325

Fourteen hours .

5-000

0-170

3-400

Sixteen hours

8-643

0-309

3-575

Eighteen hours

9-970

0-277

2-778

4-769

0-170

3-565

Twenty-two hours

7-578

0-293

3-866

Disregarding slight variations in this table, which might
be accidental, it may be stated, in general terms, that the
bile commences to increase in quantity immediately after
eating ; that its flow is at its maximum from the second to
the eighth hour, during which time the quantity does not
vary to any great extent ; after the eighth hour it begins to

1 The entire quantity of bile in the twenty-four hours, estimated from these
observations by taking an average of the quantities obtained in all the observa-
tions and multiplying by forty-eight, was 833-933 grains, with 30-003 grains of
dry residue. The question of the entire quantity of bile produced by the human
subject in the twenty-four hours will be considered hereafter under the head of
excretion.

3 TO DIGESTION.

diminish, and from the twelfth hour to the time of feeding,
it is at its minimum.1 The experiments of Dr. Dalton, made
on a dog with a fistula into the duodenum, show "that the
bile passes into the intestine in by far the largest quantity
immediately after feeding, and within the first hour." 2

Though it has been pretty satisfactorily demonstrated
that the presence of the bile in the small intestine is necessary
to proper digestion, and even essential to life, and though
the variations in the flow of bile with digestion are now well
established, it must be confessed that we have hardly any
definite information concerning the mode of action of the
bile in intestinal digestion and absorption. In all proba-
bility, its action is auxiliary to that of the other digestive
fluids.

Movements of the Small Intestine.

By the contractions of the muscular coats of the small in-
testine, the alimentary mass is made to pass along the canal,
sometimes in one direction, and sometimes in another ; the
general tendency, however, being toward the caecum. The
partially digested matters which pass out at the pylorus are
prevented from returning to the stomach, by the peculiar
arrangement of the fibres which constitute the pyloric mus-
cle. The passage from the stomach to the intestine, as we
have seen, becomes constricted gradually, so that food of the
proper consistence finds its way easily into the duodenum ;

1 There is some difference in the observations of different experimenters con-
cerning the variations in the flow of bile with digestion. Bidder and Schmidt
(op. cit.} found that the flow began to increase about two hours after feeding, its
maximum being at from twelve to fifteen hours after ; Arnold (American Jour-
nal of the Medical Sciences, April, 1856, p. 467) found the maximum to occur
soon after feeding, decreasing after the fourth hour ; and Kolliker and Miiller
(American Journal of the Medical Sciences, April, 1857, p. 476) found the maxi-
mum to be between the sixth and the eighth hour.

2 DALTON, Constitution and Physiology of the Bile. — American Journal of
the Medical Sciences, October, 1857, p. 317, and Treati&i on Human Physiology^
Philadelphia, 1864, p. 190.

MOVEMENTS OF THE SMALL INTESTINE. 377

but viewed from the duodenal side, the constriction is
abrupt, so that regurgitation is generally difficult.1

Once in the intestine, the food is propelled along the
canal by peculiar movements, which have been called peri-
staltic, when their direction is toward the large intestine, and
antiperistaltic, when the direction is reversed. These move-
ments are of the character peculiar to the unstriped mus-
cular fibres; i. &, slow, gradual, the contraction enduring for
a certain time, and followed by a correspondingly slow and
gradual relaxation. Both the circular and the longitudinal
muscular layers participate in these movements. If we care-
fully watch this action in the intestines of an animal after
the abdomen has been opened, we can sometimes see a gradual
constriction produced by the action of the circular fibres at
a certain point, which is slowly propagated along the tube,
while, at the same time, the longitudinal fibres are alter-
nately contracted and relaxed in the same gradual manner,
shortening and elongating the tube and facilitating the on-
ward passage of its contents. It can readily be appreciated
how movements of this kind are capable of propelling the
alimentary mass slowly but certainly along the intestinal
tract, even when the direction is in opposition to the force of
gravity ; and how admirably these movements are calculated

1 When the stomach is empty, the pylorus is relaxed, so that the bile fre-
quently passes in from the duodenum ; but as soon as the food is passed into
the stomach by the resophagus, the pylorus becomes firmly closed. It is stated
by Magendie (Precis filementaire de Physiologic, Paris, 1836, p. 83), and this
view is adopted by some physiologists, that the pylorus allows matters to pass
with difficulty from the stomach to the intestine, but that regurgitation from the
intestine to the stomach is comparatively easy. This opinion is based upon an
experiment of Magendie, in which he showed that air contained in the stomach
could not be forced into the intestine by pressure with the hands, while the
pressure easily passed air from the duodenum iato the stomach. (Loc. cit.} It
must be remembered, however, that the muscular fibres of the pylorus are con-
nected with the stomach, and not with the intestine ; and that pressure exerted
upon the stomach would cause them to contract, but pressure upon the duodenum
would have no such effect. We have already noted that during a quiescent con-
dition of the stomach, these fibres are relaxed.

378 DIGESTION.

to thoroughly incorporate the food with the digestive fluids
and expose those parts which have been completely liquefied
to the absorbent action of the mucous membrane.

Though the mechanism of the propulsive movements of
the intestine may be studied in living animals after opening
the abdomen, or, better still, in animals just killed, the
movements thus observed do not entirely correspond with
those which take place under natural conditions. In vivi-
sections, no movements are observed at first ; but soon after
exposure of the parts, nearly the whole intestine moves like a
mass of worms. In the normal process of digestion, the
movements are never so general nor so active; they take
place more regularly and consecutively in those portions
in which the contents are most abundant, and the move-
ments are intermittent, being interrupted by long inter-
vals of repose. In Prof. Busch's case of intestinal fistula,
there existed a large ventral hernia, the coverings of which
were so thin that the peristaltic movements could be read-
ily observed. In this case, the general character of the move-
ments corresponded with what has been observed in the in-
ferior animals. It was noted that the movements were not
continuous, and that there were often intervals of rest for
more than a quarter of an hour. It was also observed that
the movements, as indicated by flow of chymous matter
from the upper end of the intestine, were intermitted with
considerable regularity during part of the night. After ten
or eleven p. M., no discharge took place for six or seven hours.
Antiperistaltic movements, producing discharge of matters
which had been introduced into the lower end of the intes-
tine, were frequently observed.

As far as has been ascertained by observations upon the
human subject and warm-blooded animals, the regular intes-
tinal movements are excited by the passage of alimentary
matter from the stomach through the tube during the natu-
ral process of digestion. By a very slow and gradual action

1 Loc. cit.

MOVEMENTS OF THE SMALL INTESTINE. 379

of the muscular coat of the intestine, its contents are passed
along, occasionally the action being reversed for a time, until
the indigestible residue, mixed with a certain quantity of
intestinal secretion, more or less modified, is discharged grad-
ually into the caput coli. These movements are apparently
not continuous, and depend somewhat upon the quantity of
matter contained in different parts of the intestinal tract. If
we are to judge from the movements in the inferior animals
after the abdomen has been opened, the intestines are con-
stantly changing their position, principally by the action of
their longitudinal muscular fibres, so that the force of gravity
does not oppose the onward passage of their contents as
much as if the relative position of the parts were constant.
There are no definite observations concerning the relative
activity of the peristaltic movements in different portions of
the intestine ; but from the fact that the jejunum is constant-
ly found empty, while the ileum contains a considerable
quantity of pultaceous matter, it would seem that the move-
ments must be more vigorous and effective in the upper por-
tions of the canal.

The gases which are constantly found in the intestine
have, according to Longet,1 an important mechanical func-
tion. They are useful, in the first place, in keeping the ca-
nal constantly distended to the proper extent, thus avoiding
the liability to disturbances in the circulation, and facilita-
ting the passage of the alimentary mass in obedience to the
peristaltic contractions. They also support the walls of the
intestine and protect these parts against concussions in walk-
ing, leaping, etc. The gases are useful, likewise, in offering
an elastic but resisting mass upon which the compressing ac-
tion of the abdominal muscles may be exerted in the acts of
straining and expiration. If we could suppose the intestinal
tube to be entirely free from gaseous contents, it is evident
that the functions above mentioned would be performed
imperfectly and with difficulty.

1 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 152.

380 DIGESTION.

There can be hardly any question that the normal move-
ments of the intestine are principally due to the impression
made upon the mucous membrane by the alimentary mat-
ters, to which is added, perhaps, the stimulant action of the
bile. It is difficult to determine with accuracy what part
the bile plays in the production of these movements, from
the fact that the normal action of the intestine is not easily
observed. In the case of intestinal fistula so often referred
to, when food was introduced into the lower end of the
canal, there was at first an abundant evacuation every twen-
ty-four hours ; but subsequently it became necessary to use
enemeta. As there T$as no communication between the
lower and the upper end of the intestine, this fact is evi-
dence that the peristaltic movements can take place with-
out the action of the bile. Experiments upon the inferior
animals concerning the influence of the bile upon the peri-
staltic movements are somewhat contradictory. When the
abdomen is opened during life, vigorous movements may
sometimes be excited by pressing bile into the intestine from
the gall-bladder ; and the same result is occasionally observed
when the bile is applied to the peritoneal surface in an ani-
mal recently killed. But the various experiments in which
the bile has been diverted from the intestine and discharged
by a fistula, taking the frequency of the alvine dejections as
a test, show that regular peristaltic movements may take
place without the intervention of the bile.

The vigorous peristaltic movements which occur soon after
death have been explained in various ways. It has been
shown that these movements are not due to a lowering of the
in temperature, or to exposure of the intestines to the air.
The latter fact may be easily verified by killing a rabbit,
when vigorous movements may be seen through the thin ab-
dominal walls, even while the cavity is unopened. According
to Schiff, the only cause of these exaggerated movements is
diminution or arrest of the circulation. This physiologist, by
compressing the abdominal aorta in a living animal, was able

MOVEMENTS OF THE SMALL INTESTINE. 381

to excite peristaltic movements in the intestine as vigorous as
those which take place after death ; and on ceasing the com-
pression, the movements were arrested.1

The nerves which are distributed to the small intestine
are derived almost exclusively from the sympathetic system.
The only part receiving filaments from the cerebro-spinal cen-
tres is the commencement of the duodenum, to which are dis-
tributed a few branches from the pneumogastric. The experi-
ments of Brachet,2 by which he attempted to prove that the
movements of the intestines were under the control of the
pneumogastric and nerves emanating from the spinal cord,
have not been verified by other observers. Recent ex-
periments render it probable that an influence, derived
from the cerebro-spinal system, is essential to the functions
of the sympathetic ganglia,3 which may account for some
of the results obtained by Brachet after dividing the spinal
cord. The experiments of Muller, however, render it cer-
tain that the peristaltic movements are to some extent under
the influence of the sympathetic nerves distributed to the in-
testines. In these experiments, movements of the intestine
were produced by galvanization of filaments of the sympa-
thetic distributed to its muscular coat, after the ordinary post-
mortem movements had ceased. The same results followed
the application of caustic potash to the semilunar ganglia ,
the movenents reappearing when the potash was applied,
" with extraordinary vivacity " in the rabbit after the abdo-
men had been opened and the movements had entirely
ceased.4 These experiments have been confirmed by Longet,
who found, however, that the movements did not take place

1 SCHIFF, in LONGET, Traite de Physiologie, Paris, 1861, tome i., p. 147.

2 BRACHET ET FOUILHOUX, Encydop'edie des Sciences Medicates (Analomie et
Physiologic], Paris, 1840, tome v.,p. 258.

3 BERNARD, Recherches Experimentales sur les Nerfs Vasculaires el Calorifiques
du grand Sympathique. — Journal de la Physiologic, Paris, 1862, tome v., p.
383.

4 MULLER, Physiologic du Systeme Nerveux, Trad, par Jourdan, Paris, 1840,
tome i., p. 122.

382 DIGESTION.

unless alimentary matters were contained in the intes-
tine.1

It must be acknowledged that very little is known con-
cerning the reflex actions which take place through the sym-
pathetic system ; but there is certainly good ground for sup-
posing that certain reflex functions are performed by this
system of nerves, one of the most important of which is the
production of peristaltic movements in obedience to the im-
pression made by alimentary substances upon the mucous
membrane. This impression is probably conveyed to the
semilunar ganglia and reflected back through the motor
nerves to the muscular coat of the intestine.

1 LONGET, Trait6 de Physiologic, Paris, 1861, tome i., p. 148.

CHAPTEE XIY.

ACTION OF THE LARGE INTESTINE.

Physiological anatomy of the large intestine — Divisions of the large intestine —
Ileo-caecal valve — Digestion in the large intestine — Contents of the large in-
testine— Composition of the faeces — Microscopic characters of the fasces — Ex-
cretine and excretoleic acid — Stercorine — Origin of stercorine — Summary of
the constitution of the faeces — Movements of the large intestine — Defecation
— Action of the sphincter and the levator ani — Gases found in the alimentary
canal— Origin of the intestinal gases.

Physiological Anatomy of the Large Intestine.

THE large intestine, so called because its diameter is great-
er than that of the rest of the intestinal tract, receives for
the most part only 'the indigestible residue of the food,
mingled with certain of the secretions which are discharged
into the small intestine. In the human subject, the processes
of digestion which take place in this part of the alimentary
canal are unimportant ; and it is probable that hardly any
thing but water is absorbed by its lining membrane. Mat-
ters are, however, stored up in the large intestine for a num-
ber of hours, and a certain amount of secretion takes place
from its follicular glands.

The entire length of the large intestine is from four to
six feet. Its diameter is greatest at its commencement, where
it measures, when moderately distended, from two and a half
to three and a half inches. According to the observations
of Brinton, the average diameter of the tube beyond the
caecum is from one and two-thirds to two and two-thirds

384: DIGESTION.

inches.1 Passing from the caecum, the canal diminishes in
calibre, gradually and very slightly, to where the sigmoid
flexure opens into the rectum. This is the narrowest portion
of the canal. Beyond .this, the rectum gradually increases
in diameter, forming a kind of pouch, which abruptly di-
minishes in size near the external opening, to form the anus.

The general direction of the large intestine is from the
cascum in the right iliac fossa, to the left iliac fossa, thus sur-
rounding the convoluted mass formed by the small intestine,
in the form of a horse-shoe. From the caecum to the rectum
the canal is known as the colon. The first division of the
colon, called the ascending colon, passes almost directly up-
ward to the under surface of the liver ; the canal here turns
at nearly a right angle, passes across the upper part of the ab-
domen, and is called the transverse colon ; it then passes down-
ward at nearly a right angle, forming the descending colon.
The last division of the colon, called the sigmoid flexure, is
situated in the left iliac fossa and is in the form of the italic
letter 8. This terminates in the rectum, which is not straight,
as its name would imply, but presents at least three distinct
curvatures, as follows : it passes first in an oblique direction
from the left sacro-iliac symphysis to* the median line op-
posite the third piece of the sacrum ; it then passes down-
ward, in the median line, following the concavity of the sa-
crum and coccyx ; and the lower portion, about an inch in
length, turns backward to terminate in the anus.

The form of the large intestine is peculiar. The caecum,
or caput coli, presents a rounded dilated cavity, continuous
with the colon above, and communicating by a transverse slit
with the ileum. At its lower portion is a small cylindrical
tube, from one to five inches in length, opening below and a
little posterior to the opening of the ileum, called the vermi-
form appendix. This is covered with peritoneum, and is pos-
sessed of a muscular and a mucous coat. It is sometimes en-

1 BRINTON, Cyclopaedia of Anatomy and Physiology, London, 1859, vol. v.,
supplement, p. 362.

ACTION OF THE LAEGE INTESTINE. 385

tirely free, and is sometimes provided with a short fold of
mesentery for a part of its length. The coats of the appen-
dix are very thick. The muscular coat consists of longitudi-
nal fibres only. The mucous membrane is provided with
tubules and closed follicles, the latter frequently being very
numerous. This little tube, which is only about one-third
of an inch in diameter, generally contains a quantity of clear,
viscid mucus. Particles of faecal matter and extraneous sub-
stances, such as seeds, sometimes find their way into its cavi-
ty, and producing ulceration, they may escape into the peri-
toneal cavity and induce fatal inflammation.1 The uses of
the vermiform appendix are unknown.

Ileo-ccecal Valve. — The most interesting anatomical pecu-
liarity of the caecum is the opening by which it receives
the contents of the small intestine. This opening is ar-
ranged in the form of a valve, known as the ileo-csecal valve,
situated at the inner and posterior portion of the caecum.
The small intestine, at its termination, presents a shallow
concavity, which is provided with a horizontal button-hole
slit opening into the caecum. The surface of the valve
which looks toward the small intestine is covered with a mu-
cous membrane provided with villi and in all respects re-
sembling the general mucous lining of the small intestine.
Viewed from the caecum, a convexity is observed correspond-
ing to the concavity upon the other side. The caecal surface
of the valve is covered with a mucous membrane identical
with the general mucous lining of the large intestine. It is
evident from an examination of these parts that pressure
from the ileum will open the slit and allow the easy passage
of the semi-fluid contents of the intestine ; but pressure from

1 During intra-uterine life, the caecum is relatively much larger than in the
adult. It afterward retracts in its lower half or two-thirds to about the diam-
eter of a crow-quill, and this forms the appendix vermiformis. This appendix
exists only in man and the quadrumana. (SAPPEY, Traite d1 Anatomic Descriptive,
Paris, 1857, tome iii., p. 202.)
25

386 DIGESTION.

the csecal side will approximate the lips of the valve, and
the greater the pressure the more firmly will the opening be
closed. The valve itself is composed of folds involving the
white fibrous tissue of the intestine (the cellular tunic of some
anatomists), and the circular muscular fibres from both the
small and the large intestine ; the whole being covered with
mucous membrane. The lips- of the valve unite at either
extremity of the slit and are prolonged on the inner surface
of the caecum, forming two raised bands or bridles ; and these
become gradually effaced and are thus continuous with the
general lining of the canal. The posterior bridle is a lit-
tle longer and more prominent than the anterior. These
assist somewhat in enabling the valve to resist pressure from
the caecal side. The longitudinal layer of muscular fibres
and the peritoneum pass directly over the attached edge of
the valve and are not involved in its folds. These give
strength to the part, and if they be divided over the valve,
gentle traction will suffice to draw out and obliterate the
folds, leaving a simple and unprotected communication be:-
tween the large and the small intestine.

Peritoneal Coat. — Like most of the other abdominal vis-
cera, the large intestine is covered by peritoneum. The
csecum is covered by this membrane only anteriorly and
laterally. It is usually bound down closely to the subjacent
parts, and its posterior surface is without a serous investment ;
though sometimes it is completely covered, and there may
be even a short mesocsecum. The ascending colon is like-
wise covered only in front, and is closely attached to the
subjacent parts. The same arrangement is found in the
descending colon. The transverse colon is almost completely
invested with peritoneum ; and the two folds forming the trans-
verse mesocolon split to pass over the tube above and below,
uniting again in front to form the great omentum. The trans-
verse colon is consequently quite movable. In the course of
the colon and the upper part of the rectum, particularly on

MUSCULAR COAT. 387

the transverse colon, are found a number of little sacculated
pouches filled with fat, called the appendices epiploicse.
The sigmoid flexure of the colon is invested with peritoneum,
except at the attachment of the iliac mesocolon. This divi-
sion ,,of the intestine is capable of considerable motion. The
upper part of the rectum is almost completely covered by
peritoneum, and is but loosely held in place. The middle
portion is closely bound down, and is only covered with peri-
toneum anteriorly and laterally. The lowest portion of the
rectum has no peritoneal covering.

Muscular Coat. — The muscular fibres of the large intes-
tine have an arrangement quite different from that which
exists in the small intestine. The external, longitudinal
layer, instead of extending over the whole tube, is arranged
in three distinct bands, which commence in the caecum at
the vermiform appendix. Passing along the ascending co-
lon, one of the bands is situated anteriorly, and the others
latero-posteriorly. On the transverse colon, the anterior band
becomes inferior, and the two latero-posterior bands become
respectively postero-superior and postero-inferior. On the de-
scending colon and the sigmoid flexure, the muscular bands
resume the relative position which they had on the ascending
colon. As these longitudinal fibres pass to the rectum, the
anterior and the external bands unite to pass down on the
anterior surface of the canal, while the posterior band passes
down on its posterior surface. Thus the three bands are here
formed into two. These two bands as they pass downward,
though remaining distinct, become much wider ; and longitu-
dinal muscular fibres commencing at the rectum are situated
between them, so that this part of the canal, especially in its
lower portion, is covered with longitudinal fibres in a pretty
uniform layer.

The termimation of the muscular fibres of the rectum has
been closely studied by Sappey. He has found that as far
as their terminations are concerned, the fibres may be divided

388 DIGESTION.

into an external, a middle, and an internal layer. The pos-
terior fibres of the external layer pass away from the lower
portion of the rectum, are reflected backward along the con-
cavity of the sacrum, and are attached to the promontory.
These fibres, which are generally pale, Sappey proposes to
designate as retractors of the anus. A few of the posterior
fibres are attached to the aponeurosis and the parts between
the coccyx and the promontory. In front, the external fibres
are attached to the aponeurosis which covers the vesiculse
seminales, and laterally they are inserted into the deep pel-
vic fascia. The termination of the middle layer of the
fibres is less clearly made out. Those situated at the sides
of the rectum are inserted into " a very dense cellulo-fibrous
band, which, by its opposite surface, gives insertion to a
great number of fibres of the levator ani." The others are
many of them continuous with the fibres of the levator
ani as they pass along the floor of the pelvis. Some of the
fibres of the deep layer are attached by little tendons
which pass between the external and the internal sphincter
to the deep portions of the skin which encircle the anus.1
The importance of closely studying the attachments of these
fibres will be appreciated when we come to treat of defecation.
Over the caecum and the colon, the anterior band of mus-
cular fibres is from one-third to one-half an inch in width.
The postero-external band is not more than half as wide, and
the postero-internal band is even narrower. The muscular
bands are much shorter than the canal itself, and their attach-
ment to the walls gives the intestine a peculiar sacculated ap-
pearance. That this is produced by the arrangement of the
muscular fibres may be demonstrated by dividing them in
various places or removing them entirely, when the canal may
be extended to double its original length. Between the bands
there are no longitudinal muscular fibres ; but circular or
transverse muscular fibres exist throughout the whole length
of the large intestine. In the csecum and colon, the circular

1 SAPPEY, op. cit., pp. 226, 227.

MUCOUS COAT. 389

fibres are so pale and the layers are so thin that their pres-
ence is demonstrated with great difficulty. In the rectum
they are somewhat more numerous. About an inch above
the anus the circular fibres are collected into a pretty well-
marked muscular ring, which has been called the internal
sphincter.

Mucous Goat. — The mucous lining of the large intestine
presents several important points of difference from that which
is found in the small intestine. It is paler, somewhat thick-
er, firmer, and more closely adherent to the subjacent parts.
In no part of this membrane are there any folds, like those
which form the valvulse conniventes of the small intestine ;
and the surface is perfectly smooth and free from villosities.

Throughout the entire membrane, from the ileo-csecal
valve to the anus, are innumerable orifices which lead to
simple follicular glands. These structures resemble in all
respects the follicles of the small intestine, except that they
are a little longer, owing to the greater thickness of the mem-
brane, and are wider, and rather more numerous. Among
these small follicular openings are found, scattered irregularly
throughout the membrane, larger openings which lead to
utricular glands, resembling the closed follicles, in general
structure, except that they have an orifice opening into the
cavity of the intestine, which is sometimes so large as to be
visible to the naked eye.1 The number of these glands is very
variable, and they are irregularly disseminated throughout the
intestine in company with the closed follicles, except in the
rectum, where they are absent. In the caecum and colon, a
number of isolated closed follicles are generally found, which
are identical in structure with the solitary glands of the small
intestine. These are exceedingly variable, both in number
and size.

The mucous membrane of the rectum, in the upper
three-fourths of its extent, does not differ materially from that

1 SAPPEY, op. c^.,tome iii., p. 192.

390 DIGESTION.

of the colon. In the lower fourth, the fibrous tissue by which
the lining membrane is united to the subjacent muscular
coat is loose, and the membrane, when the canal is empty, is
thrown into a great number of irregular folds. At the site
of the internal sphincter, five or six little semilunar valves
have been observed with their concavities directed toward the
colon. These form an irregular festooned line which surrounds
the canal ; their folds, however, are small and have no tenden-
cy to obstruct the passage of faecal matters. The simple folli-
cles are particularly abundant in the rectum, and the mem-
brane is constantly covered with a thin coating of mucus.
Another peculiarity to be noted in the mucous membrane
of the lower portions of the rectum, is its great vascularity ;
the veins, especially, being very numerous.

Finally, the rectum terminates in the anus, a button-hole
orifice, situated a little in front of the coccyx, which is kept
closed and somewhat retracted, except during the passage of
the faeces, by the powerful external sphincter. This muscle
is composed entirely of red or striated fibres, which are ar-
ranged in the form of an ellipse, its long diameter being
antero-posterior.

It is now almost universally admitted that the digestion of
all classes of alimentary substances is completed either in the
stomach or the small intestine, and that the mucous membrane
of the large intestine does not secrete a fluid endowed with
any well marked digestive properties. The simple follicles,
the closed follicles, and the utricular glands, produce a glairy
mucus, which, as far as we know, serves merely to lubricate
the canal. This has never been obtained in sufficient quan-
tity to admit of any accurate investigation into its properties.1

1 It is now pretty generally conceded by practical physicians that it is pos-
sible to support the vital powers for a time by nutrient matters introduced into
the large intestine by injection. As can readily be .understood, there are ob-
stacles in the employment of this method of alimentation which render its ap-
plication difficult, if not impossible, in many cases ; but instances have been
reported in which it has been used for a long time with complete success. One

MUCOUS COAT. 391

In studying the changes which the alimentary mass un-
dergoes in its passage through the small intestine, we have
seen that in this portion of the canal the great part of all
the nutritive material is not only liquefied, but absorbed.
Sometimes fragments of muscular fibre, oil-globules, and other
matters in a state of partial disintegration are to be detected
in the fseces by the microscope ; but generally this is either
the result of taking an excessive quantity of these substances,
or it depends upon some derangement of the digestive ap-
paratus ; though muscular fibres deeply colored with bile,
but still distinctly striated, were constantly found in the
fseces by Wehsarg.1 When intestinal digestion takes place
with regularity, the transformation of the alimentary mass
into faecal matter is slow and gradual. As the contents of
the stomach are passed little by little into the duodenum, the
chymous mass becomes of a bright-yellow color, and its
fluidity is increased, from the admixture of bile and pancre-

of the most remarkable of these was reported in the American Journal of the
Medical /Sciences, October, 1852, by Dr. J. L. Pierce. In this case, the patient,
a female about twenty-sis years of age, suffered from a disorder of the stomach,
in which all articles of food were rejected within a few moments after they had
been taken. She was actually in danger of death from inanition, when it was
proposed to nourish her entirely by enemata. Under the direction of her physi-
cian, she took injections of lamb or mutton broth, about half a pint at a time, every
three hours, for about three months. During the first week of this treatment,
she was allowed occasionally a little gum-arabic water or pure water, not to ex-
ceed a teaspoonful at a time ; but after that, nothing was taken by the mouth.
Under this treatment the patient improved in health and strength, began grad-
ually to take food by the mouth at the end of three months, and finally recovered.
(Loc. cit., p. 571 et seq.)

It is difficult to determine whether nutritive matters thus introduced into the
large intestine undergo any change which may be likened to digestion ; but
there can be no doubt that they are in great part absorbed. A French experi-
menter, M. Bouisson, reports an observation in which a dog was first purged,
then kept fasting for two days, when a quantity of milk was injected into the
large intestine. The animal was killed a short time after, and the lymphatics from
the large intestine were found filled with white chyle. (Etudes sur le Chyle. —
Gazette Medicale de Paris, 1844, tome xii., p. 522.)

1 WEHSARG, MiTcroscopische und Chemiche Unterwichungen der Faeces g&~
sunder, erwachscner Menschen, Giessen, 1833, p. 65.

392 DIGESTION.

atic fluid. In passing along the canal, the consistence of
the mass gradually diminishes, from the absorption of its li-
quid portions, and the color becomes darker ; and by the time
that the contents of the ileum are ready to pass into the
csecum, the greatest part of those substances which, we have
recognized as alimentary principles have become changed and
absorbed. The various forms of starchy and saccharine prin-
ciples, unless they have been taken in excessive quantity, soon
disappear from the intestine ; and the glucose, which is the re-
sult of their digestion, may be recognized in the blood of the
portal system. As a rule, fatty matters are not found in the
lower part of the ileum, having passed into the lacteals in
the form of an emulsion. Neither fibrin, albumen, nor
caseine can be detected in the ileum ; and, as we have seen,
the muscular substance, as recognized by its microscopic
characters, becomes gradually disintegrated and is lost — ex-
cept a few isolated fragments deeply colored with bile — some
time before the undigested residue passes into the large in-
testine.

In the human subject, those portions of the food which re-
sist the successive and combined action of the different diges-
tive secretions, are derived chiefly from the vegetable kingdom.
Hard vegetable seeds, the cortex of the cereals, spiral vessels,
and, in fine, all parts which are composed largely of cellulose,
pass through the intestinal canal without much change.
These substances form, in the faeces, the greatest part of what
can be recognized as the residue of matters taken as food. It
is well known that an exclusively animal diet, particularly if
the nutritious principles be taken in a concentrated and read-
ily assimilable form, leaves very little undigested matter to
pass into the large intestine, and gives to the faeces a charac-
ter quite different from that which is observed in herbivorous
animals, or in man, when subjected to an exclusively vege-
table diet. The characters of the residue of the digestion of
albuminoid substances are not very distinct. As a rule,
none of the albuminoids are to be recognized in the healthy

CONTENTS OF THE LARGE INTESTINE. 393

faeces by the ordinary tests. This has been ascertained by
Braconnot, by experiments on pigeons, and by Blondlot, by
experiments on dogs. Blondlot fed .a dog for eight days
with hashed beef mixed with about a quarter of its weight
of liquid albumen, and never could detect either albumen
or fibrin in the faeces. He fed the same dog for four days
on the spongy structure of bones roughly comminuted in a
mortar, and by heating the fseces with water in a Papin's
digester, he was unable to extract any gelatine.1 Of the
various animal substances which may find their way into the
alimentary canal, mucus is apparently the most refractory
to the action of the digestive fluids, none of which seem to
affect it in the slightest degree. In normal alimentation, then,
the quantity of nitrogenized matter which escapes digestion
is very slight, consisting chiefly of tendinous or ligamentous
structure, elastic tissue, skin, and tissues of like nature. "When
the quantity of animal matter taken is excessive, the residue
is greater, but the principles are in a putrescent condi-
tion and cannot usually be recognized by their ordinary
characters.

Many insoluble inorganic substances are taken with the
food and appear unchanged in the faeces. The faeces of
dog? fed exclusively on bones, which were formerly adminis-
tered internally as a remedy for epilepsy, under the name of
album Grcecum, are composed almost entirely of calcareous
matter. With regard to the ordinary inorganic constituents
of the faeces, however, it is difficult to say how much is de-
rived from the ingesta, and how much from the different in-
testinal secretions.

Contents of the Large Intestine.

When the contents of the small intestine have passed the
ileo-caecal valve, they become materially changed in their
general character, partly from admixture with the secretions
of this portion of the canal, and are then known as the faeces.

1 BLONDLOT, Traite Analyiique de la Digestion, Paris, 1843, p. 441.

394: DIGESTION.

The most palpable of these changes relate to consistence,
color, and odor.

Faecal matter has a much firmer consistence than the
contents of the ileum ; which is due to a constant absorp-
tion of the liquid portions. As a rule, the consistence is
great in proportion to the length of time that the faeces re-
main in the large intestine; and this is variable in different
persons and in the same -person, in health, depending some-
what upon the character of the food.

The color changes from the yellow, more or less bright,
which is observed in the ileum, to the dark yellowish-brown,
characteristic of the faeces. Though the bile-pigment cannot
usually be recognized by the ordinary tests, it is this which
gives to the contents of the large intestine their peculiar
color, which is lost when the bile is not discharged into the
duodenum. In a specimen of healthy human faeces which
had been dried, extracted with alcohol, the alcoholic solution
precipitated with ether, and the precipitate dissolved in dis-
tilled water, we failed to detect the slightest trace of the
biliary salts by Pettenkofer's test. In a watery extract of the
same faeces, the addition of nitric acid also failed to show
the reaction of the coloring matter of the bile.1 The color,
however, has been found to vary considerably with the diet.
Wehsarg has shown that with a mixed diet, the color is yel-
lowish-brown ; with an exclusively flesh-diet, it is much
darker ; and witli a milk-diet, it is more yellow.8

The odor of the faeces, which is characteristic and quite
different from that of the contents of the ileum, is somewhat
variable, and is due in part to the peculiar decomposition
of the residue of the food, in part to the decomposition of

1 Prof. Dalton, in comparative analyses of the contents of the small and the
large intestine in dogs, in which the matters were first evaporated to dryness, the
residue extracted with absolute alcohol and then precipitated with ether, always
detected biliary matters by Pettenkofer's test in the contents of the small intes-
tine, while they were invariably absent in the contents of the large intestine.
(Treatise on Human Physiology, Philadelphia, 1864, p. 193.)

2 Op., cit.

CONTENTS OF THE LAEGE INTESTINE. 395

the bile, and in part to matters secreted by the mucous
membrane of the colon and the glands near the anus.

The entire quantity of faeces in the twenty-four hours
was found by Wehsarg to be about 4'6 ounces. This was
the mean of seventeen observations ; the largest quantity
being 10*8 ounces, and "the smallest 2'4 ounces.1 As the
average of five examinations of his own faeces on successive
days, Dr. Hammond found the entire quantity in the twenty-
four hours to be about 5*24 ounces.2

The reaction of the faeces is undoubtedly very variable,
depending chiefly upon the character of the food. Marcet
found the human excrements always alkaline.3 Wehsarg,
on the other hand, found the reaction generally acid, but
very frequently alkaline or neutral.

The first accurate analyses of the faeces were made by
Berzelius ; but the great advances which have been made in
physiological chemistry since that time have enabled later
observers to arrive at results much more definite and satis-
factory. The recent researches into the composition of the
healthy faeces by "Wehsarg, already referred to, have thrown
much light upon the nature of the constituents derived from
the food and the bile, as well as. the proportions of the va-
rious inorganic salts. Marcet has lately discovered a crys-
tallizable substance peculiar to the human faeces ; 4 and we
have recently shown that probably the most important excre-
mentitious principle discharged by the rectum is derived

1 Op. tit., p. 62.

2 HAMMOND, Experimental Researches relative to the Nutritive Value of Albu-
men, Starch, and Gum, when singly and exclusively used as Food, Philadelphia,
1857, p. 18.

3 MARCET, An Account of the Organic Chemical Constituents or Immediate
Principles of the Excrements of Man and Animals in the Healthy Slate.— Philo-
sophical Transactions, London, 1854, p. 265.

4 MARCET, An Account of the Organic Chemical Constituents or Immediate
Principles of the Excrements of Man and Animals in the Healthy State. — Philo-
sophical Transactions, -London, 1854, p. 265 et seq. ; and, On the Immediate Prin-
ciples of the Human Excrements in the Healthy State. — Idem., 1857, p. 403 ct seq.

396 DIGESTION.

from the bile, and is a peculiar modification of cholesterine.1
Analyses of the faeces have also been made by Simon and
Percy,2 Hiring,3 Lehmann,4 and many others. The observa-
tions of Simon and of Ihring relate chiefly to the faeces in
disease. Most of our statements concerning the composition
of the faeces in health will be derived from the researches of
Wehsarg and of Marcet, and our own observations.

The proportions of water and solid matter in the fseces is
variable. Berzelius found in the healthy human fseces 73*3
parts of water and 26*7 parts of solid residue.6 The average
of seventeen observations by "Wehsarg was precisely the same.

Dr. Hammond, in a series of observations made upon his
own person for five successive days, while in perfect health,
found the average proportion of water to the solid matters
of the faeces to be as 730 to 270.° In a single specimen of
perfectly healthy faeces, the entire quantity passed for the
twenty-four hours (seven and a half ounces), we found the
proportion of water to solid matter to be as Y16 to 284.

In the observations of "Wehsarg, the mean quantity of
solid matter discharged in the faeces in the twenty-four hours
was 463 grains ; the extremes being 882*8 grains and 251*6
grains. The proportion of undigested matters in the solid
residue was very small, averaging but little more than ten
per cent. ; the mean quantity in the twenty-four hours in ten
observations being but 52*5 grains. This was found, how-

1 Experimental Researches into a New Excretory . Function of the Liver, con-
sisting in the Removal of Cholesterine from the Blood, and its Discharge from the
Body in the Form of Stercorine (the Seroline of Boudcf). — American Journal of
the Medical Sciences, October, 1862.

2 SIMON, Animal Chemistry with Reference to the Physiology and Pathology
of Man, Philadelphia, 1846, p. 671 et seq.

3 IHRING, Mikroscopish-Chemische Untersuchungen menschlichen Faeces unter
verschiedenen pathologischen Verhdltnissen, Giessen, 1852.

4 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. i., p. 517 etseq.

5 BERZELIUS, Analyse de la Matiere Excrew,entitielle de VHomme. — Annales de
Chimie, Paris, 1807, tome Ixi., p. 321.

6 HAMMOND, op. cit. The above is calculated from the results given in the
table (loc. cit., p. 18).

CONTENTS OF THE LARGE INTESTINE. 397

ever, to be exceedingly variable ; the largest quantity being
126*5 grains, and the smallest 12*5 grains.

Microscopical examination of the faeces reveals the various
vegetable and animal structures which we have referred to
as escaping the action of the digestive fluids. Wehsarg also
found a " finely divided faecal matter " of indefinite structure^
but containing partly disintegrated intestinal epithelium
Crystals of cholesterine were never observed. "Whenever the
matter was neutral or alkaline, crystals of the ammonio-
magnesian phosphate were found.1 Mucus is also found in
variable quantity, in the faeces, with desquamated epithe-
lium, and a few leucocytes.

The quantity of inorganic salts in the faeces is not great.
In addition to the aminonio-magnesian phosphate, phosphate
of magnesia, phosphate of lime, and a small quantity of iron
have been found. The chlorides are either absent or present
only in small quantity.

Marcet has pretty generally found in the human faeces
a substance possessing the characters of margaric acid, and
volatile fatty acids ; the latter free, however, from butyric
acid. Gystine is mentioned as an occasional constituent.2
He also found a coloring matter like that extracted by Yer-
deil from the blood and by Harley from the urine. This is
probably a modification of biliverdine.

In 1854, Marcet described a new substance in the human
faeces, which he called excretine, and an acid called excre-
toleic acid, which he supposed to be a compound of excre-
tine. These principles and the one which we described in
1862, under the name of stercorine, are, as far as we know,
the only ones which have been recognized as characteristic

1 Wehsarg mentions amorphous fat as always found in the fasces on micro-
scopic examination (p. 65). We have seen that the saponifiable fats cannot usu-
ally be separated from the fasces ; while amorphous stercorine might easily be
mistaken for fat. Wehsarg does not indicate the exact nature of the fatty mat-
ters which he observed.

2 MARCET, Philosophical Transactions, 1854

398 DIGESTION.

of the normal faeces ; and the stercorine we have found to be
one of the most distinct and important of the excrementitious
principles in the body.1 The relations of excretine to the
process of destructive assimilation of the tissues have not
been so clearly indicated.

Excretine and Excretoleic Acid. — Excretine was obtained
by Marcet from the healthy human faeces in the following
way : The faeces were first treated with boiling alcohol until
nothing more could ' be extracted. • This alcoholic solution
was acid and deposited a sediment on cooling. Milk of lime
was then added to the solution, producing a yellowish-brown
precipitate, and leaving the fluid of a clear straw-color. The
precipitate was then collected on a filter, dried, afterward agi-
tated with ether and filtered, forming a clear yellow solution.
In from one to three days, beautiful long silky crystals of
excretine were formed, generally collected into tufts adhe-
ring to the sides of the vessel. Examined by the microscope,
these were found to consist of acicular four-sided prisms of
variable size. This substance is insoluble in water, slightly
soluble in cold alcohol, but very soluble in ether and hot
alcohol. Its alcoholic solutions are faintly, though distinctly,
alkaline. Its fusing point is from 203° to 205° Fahr. It
may be boiled with potash for hours without undergoing
saponification.* In a second paper by Marcet, published in
1857, the composition of excretine is given as C^IPO'S1. It
was also found that its crystallization was facilitated by cold.*
Apparently, the quantity of excretine contained in the faeces

J In 1833, Boudet described a new substance as existing in the serum of the
blood, which he called Seroline. (Nouvclles Recherches sur la Composition du
Serum du Sang. — Annales de Chimie et de Physique, Paris, 1833, tome Hi., p.
337.) This is the substance which we discovered in the faeces, and have de-
scribed under the name of Stercorine.

2 MAECET, Philosophical Transactions^ 1854, p. 265 et seq.

8 Excretine has not yet been made to enter into any definite combinations,
and its formula is calculated on the assumption that one equivalent of excretine
contains one equivalent of sulphur.

EXCRETINE AND EXCRETOLEIC ACID. 399

is not very great, as only 12*6 grains were obtained by
Marcet from nine evacuations.1

We have very little definite information concerning the
production of excretine. Marcet examined, on one occasion,
the contents of the small intestine of a man that had died of
disease of the heart, without finding any excretine.2 It is
probable that this principle is formed in the large intestine,
though further observations are wanting on this point.

The substance called excretoleic acid is very indefinite in
its composition and properties. It is described as an olive-
colored fatty acid, insoluble in water, non-saponifiable, and
very soluble in ether and in hot alcohol. It fuses at from
77° to 79° Fahr.

Stercorine. — This principle, which we discovered in the
faeces in 1862, was described by Boudet in 1833, as existing
in excessively minute quantity in the serum of the blood,
and was called by him seroline. As we found it to be the
most abundant and characteristic constituent of the sterco-
raceous matter, we proposed to call it stercorine ; 3 particu-
larly as our researches led us to the opinion that it really
does not exist in the serum, but is formed from cholesterine
by the processes employed for its extraction.

Stercorine may be extracted in the following way : The
fseces are first evaporated to dryness, pulverized, and treated
with ether. The ether extract is then passed through animal
charcoal, fresh ether being added until the original quantity
of the ether extract has passed through. It is impossible to
decolorize the solution entirely by this process ; but it should
pass through perfectly clear and of a pale amber color. The
ether is then evaporated, and the residue extracted with boil-
ing alcohol. This alcoholic solution is evaporated, and the
residue treated with a solution of caustic potash for one or

1 MARCET, Philosophical Transactions, 1857, p. 410.

9 Ibid., 1854, p. 269.

3 American Journal of the Medical Sciences, October, 1862.

400 DIGESTION.

two hours at a temperature a little below the boiling point,
by which all the saponifiable fats are dissolved. The mix-
ture is then largely diluted with water, thrown upon a
filter, and washed until the fluid which passes through is
neutral and perfectly clear. The filter is then carefully dried,
and the residue washed out with ether. The ether solution
is then evaporated, extracted with boiling alcohol, and the
alcoholic solution evaporated. The residue of this last evap-
oration is composed of pure stercorine.

"When first obtained, the stercorine is a clear, slightly
amber, oily substance, about the consistence of Canada bal-
sam used in microscopic preparations. In four or five days
it begins to show the characteristic crystals. These are few
in number at first, but soon the entire mass assumes a crys-
talline form. In one analysis we obtained from seven and a
half ounces of normal human faeces (the entire quantity for
the twenty-four hours), 10'4rl7 grains of stercorine, the ex-
tract consisting of nothing but crystals. This was all the
stercorine to be extracted from the regular daily evacuation
of a healthy male twenty-six years of age and weighing about
one hundred and sixty pounds. In the absence of other in-
vestigations, the daily quantity of this substance excreted
may be assumed to be not far from ten grains.

In many regards, stercorine bears a close resemblance to
cholesterine. It is neutral, inodorous, and insoluble in water
and in a solution of potash. It is soluble in ether and hot
alcohol, but is almost insoluble in cold alcohol. A red color
is produced when it is treated with strong sulphuric acid. It
may be easily distinguished from cholesterine, however, by
the form of its crystals. It fuses at a low temperature, 96*8°
Fahr., while cholesterine fuses at 293° Fahr.

Stercorine crystallizes in the form of thin delicate nee-
dles, frequently mixed with clear rounded globules, which
are probably composed of the same substance in a non-crys-
talline form. When the crystals are of considerable size, the
borders near their extremities are split longitudinally for a

EXCKETINE AND EXCBETOLEIC ACID.

401

Fig. 4.

short distance. The crystals are frequently arranged in

bundles, as in Fig. 4, in which they are represented as seen

under a T\ inch ob-

jective. In Fig. 5

the crystals are rep-

resented as seen un-

der a -i inch objec-

tive. These crystals

cannot be confound-

ed with excretine,

which crystallizes in

the form of regular,

four-sided prisms, nor

with the thin rhom-

boidal or rectangular

tablets of cholester-

ine. They are iden-

tical with the crys-

tals of seroline figured by Robin and Ycrdiel.1

There can be no
doubt with regard to
the origin of the ster-
corine which exists in
the fasces. We have
found that whenever
the bile is not dis-
charged into the du-
odenum, as is prob-
ably the case, for a
time, in icterus ac-
companied with clay-
colored evacuations,
stercorine is not to

V>p rliar>nirm*c»rl ir» -fTio
U1SCOV6I

Tn
j.11

Stercorine from the human f,eces, T*5 inch objective.

Fig. 5.

ATIP

Stercorinc from the same specimen after it had been
melted, placed upon a glass slide, covered with thin
glass, and allowed to crystallize. The crystalliza-
tion was very slow, occupying some weeks.

1 ROBIN ET VERDIEL, Chimie Anatomique, Paris, 1853, Atlas, PI. xxxvi., Fig. 2.
26

4:02 DIGESTION.

case of this kind, in which the faeces were subjected to ex-
amination, the matters extracted with hot alcohol were en-
tirely dissolved by boiling for fifteen minutes with a solu-
tion of potash, showing the absence of cholesterine and ster-
corine. In another examination of the faeces from this
patient, made nineteen days after, when the icterus had
almost entirely disappeared and the evacuations had be-
come normal, stercorine was discovered. Taking the esti-
mates which have been made of the entire quantity of bile
discharged into the intestine in the twenty-four hours, by
Bidder and Schmidt, and Dalton, a comparison of the total
quantity of cholesterine contained in the bile with the quan-
tity of stercorine actually discharged shows a correspondence
which serves as an additional argument in favor of the view
that stercorine is formed from a modification of cholesterine
in its passage along the intestinal canal.

These facts showT conclusively that the cholesterine of the
bile, in its passage through the intestine, is changed into
stercorine. Both of these principles are crystalline, non-
saponifiable, are extracted by the same chemical manipula-
tions, and behave in the same way when treated with sul-
phuric acid. The stercorine must be regarded as a slight
modification of cholesterine, the excrementitious principle
of the bile.1

"We have found that the change of cholesterine into ster-
corine is directly connected with the process of intestinal

1 Our researches into the functiou of cholesterine have left no doubt that this
is an excrementitious principle hardly second in importance to urea. We have
found that cholesterine is always more abundant in the blood coming from the
brain than in the blood of the general arterial system, or in the venous blood
from other parts ; that its quantity is hardly appreciable in venous blood from
the paralyzed side in hemiplegia ; and that it is separated from the blood by
the liver. We have also shown that in cases of serious structural disease of
the liver, accompanied by symptoms pointing to blood-poisoning, cholesterine
accumulates in the blood, constituting a condition which we have called choles-
terasmia. This subject will be fully discussed under the head of Excretion. For
a full account of our observations upon the function of cholesterine see The
American Journal of the Medical Sciences, October, 1862.

SUMMABY. 403

digestion. If an animal be kept for some days without food-,
cholesterine will be found in the faeces, though for a few
days stercorine is also present. It is generally recognized by
those who have analyzed the faeces, that cholesterine does
not exist in the normal evacuations ; but whenever digestion
is arrested, the bile being constantly discharged into the
duodenum, cholesterine is found in large quantity. For ex-
ample, in hibernating animals, cholesterine is always present
in the faeces.1 The same is true of the contents of the intes-
tines during foetal life ; the meconium always containing a
large quantity of cholesterine, which disappears from the
evacuations when the digestive function becomes established.

Summary. — The entire quantity of faeces passed in the
twenty-four hours is from four to seven ounces. The color
may be of any shade between a yellow, a yellowish-brown,
and a very dark brown. The odor of the faeces is sui generis,
and is developed only after the matters have been discharged
by the ileum into the large intestine.

The reaction of the faeces may be alkaline, neutral, or
acid ; depending, probably, upon changes which take place
in the undigested residue of the food.

The proportion of solid residue in the faeces after evapo-
ration is about two hundred and seventy parts per thousand.
The absolute quantity of solid matter discharged in the faeces
in the twenty-four hours is about four hundred and sixty
grains ; only about ten per cent, of which consists of undi-
gested matters.

The matters contained in the faeces which are derived
from the food consist largely of vegetable structures, such as
cellulose, spiral vessels, the cortex of grains, etc. The mat-
ters derived from animal food are, pieces of tendinous or
elastic structure, ill-defined grumous matter, particles of mus-
cular tissue in various stages of disintegration, the inor-

1 MARCET, op. dt., — Philosophical Transactions, London, 1854, p. 278 .

404: DIGESTION.

garde constituents of bone, etc. The faeces sometimes contain
a small quantity of fatty acids.

The inorganic matters contained in the faeces consist
chiefly of the phosphate of magnesia, with the phosphate of
lime and a little iron. "When the reaction is neutral or
alkaline, crystals of the ammonio-magnesiaii phosphate are
found. Mucus exists in the faeces in small quantity, with epi-
thelium and a few leucocytes.

The only characteristic excrementitious constituents of the
faeces which have yet been described are : stercorine, the
most important excrementitious principle discharged by the
rectum, and excretine and excretoleic acid, which have been
found as yet only in the human faeces. Though the color of
the faeces is undoubtedly due to a transformation of the col-
oring matter of the bile, neither the biliary salts nor biliver-
dine are to be detected in the large intestine by the ordinary
tests. The coloring matters of the faeces resemble the color-
ing matters which have been extracted from the blood and
the urine.

Movements of the Large Intestine. — Movements of the
same general character which we have noted in the small
intestine occur in the large intestine ; though the peculiari-
ties in the arrangement of the muscular fibres and the more
solid consistence of the contents render these movements
somewhat distinctive. In all instances where these move-
ments have been observed in the human subject or the lower
animals, they have been found to be less vigorous and rapid
than the contractions of the small intestine. Indeed, when
the abdominal organs are exposed, either in a living animal
or immediately after death, movements of the large intestine
are generally not observed, except on the application of me-
chanical or galvanic irritation ; and they are then more cir-
cumscribed -and much less marked than in any other part of
the alimentary canal. In the rabbit, in which the colon is
very large, the few spontaneous movements which are some-

MOVEMENTS OP THE LAKGE INTESTINE. 405

times seen on opening the abdomen immediately after death
are feeble and irregular, particularly in the caecum. That
the faeces remain for a considerable time in some of the sac-
culated pouches of the colon is evident from the appearance
which they sometimes present of having been moulded to
the shape of the canal. This appearance is frequently ob-
served in the dejections, which are then said to be " fig-
ured."

In the caecum, the pressure of matters received from the
ileum forces the mass onward into the ascending colon, and
the contractions of its muscular fibres are undoubtedly slight
and ineffective. Once in the colon it is easy to see how the
contractions of the muscular structure (the longitudinal bands
shortening the canal, and the transverse fibres contracting
below and relaxing above) are capable of passing the faecal
mass slowly onward. Though the transverse fibres are thin
and seemingly of little power, they are undoubtedly power-
ful enough to empty the sacculi, when assisted by the move-
ments of the longitudinal fibres, especially as the canal is
never completely filled and the fasces are frequently in the
form of small moulded lumps.

By these slow and gradual movements, the contents of
the large intestine are passed toward the sigmoid flexure of
the colon, where they are arrested until the period arrives
for their final discharge. The time occupied in the passage
of the faeces through the ascending, transverse, and descend-
ing colon is undoubtedly variable in different persons, as we
find great variations in the intervals between the acts of
defecation. During their passage along the colon, the con-
tents of the canal assume more and more of the normal
faecal consistence and odor, and become slightly coated with
the mucous secretion of the parts.

It has been pretty conclusively shown that the accumula-
tion of faeces generally takes place in the sigmoid flexure ; for
under normal conditions, the rectum is found empty and con-
tracted. This part of the colon is much more movable than

406 DIGESTION.

other portions, and is better calculated as a receptacle for
faeces.1 At certain tolerably regular intervals, the faecal
matter is passed into the rectum and is then almost imme-
diately discharged from the body.

Defecation.

In health, expulsion of fsecal matters takes place with
regularity generally once in the twenty-four hours. This
rule, however, is by no means invariable, and dejections may
habitually occur twice in the day, or every second or third
day, within the limits of perfect health. It is well known
that habit has a great influence upon the regularity of defe-
cation; and sometimes, in cases of irregularity, physicians
have recommended patients to make an effort to void the
faeces at a certain time every day, this practice being fre-
quently followed by the best results. At the time when def-
ecation ordinarily takes place, a peculiar sensation is experi-
enced calling for an evacuation of the bowels ; and if this be
disregarded, the desire may pass away, and after a little time,
the act becomes impossible. Under these circumstances, it is
probable that the faeces are passed out of the rectum by anti-
peristaltic action.

The condition which immediately precedes the desire for
defecation is probably the descent of the contents of the
sigmoid flexure of the colon into the rectum. It was formerly
thought that the faeces constantly accumulated in the dilated
portion of the rectum, where they remained until an evac-
uation took place ; but the arguments of O'Beirne against
such a view are conclusive. He has demonstrated by numer-
ous explorations in the human subject, that under ordinary
conditions, the rectum is contracted, and contains neither
faeces nor gas. It is, indeed, a fact familiar to every surgeon
that the rectum usually contains nothing which can be
reached by the finger in physical examinations, and that

1 O'BEIRNE, New Views of the Process of Defecation, Washington, 1834,
pp. 11, 12.

DEFECATION. 407

paralysis or section of the muscles which close the anus by
no means involves, necessarily, a constant passage of faecal
matter. O'Beirne not only found the rectum empty and
presenting a certain amount of resistance to the passage
of injected fluids, but on passing a stomach-tube into the
bowel, after penetrating from six to eight inches, it passed
into a space in which its extremity could be moved with
great freedom, and there was instantly a rush of flatus, of
fluid fasces, or of both, through the tube. In some instances in
which nothing escaped through the tube, the instrument con-
veyed to the hand an impression of having entered a solid
mass ; and on being withdrawn contained solid faeces in its
upper portion.1 According to this observer, the sensation
which leads to an effort to discharge the faeces is produced by
the accumulation of matters in the sigmoid flexure, which
finally present at the contracted portion of the rectum just at
its commencement. This constriction, situated at the most
superior portion of the rectum, is sometimes spoken of as the
sphincter of O'Beirne.

The above is undoubtedly the mechanism of the descent
of faecal matter into the rectum in defecation, as the act is
usually performed ; but under certain circumstances, faeces
must accumulate in the dilated portion of the rectum. Ordi-
narily, the discharge of faeces only takes place after the efforts
have been continued for a certain time ; and when the evacua-
tion is " figured," the whole length discharged frequently ex-
ceeds so much the length of the rectum, that it is evident that a
portion of it must have come from the colon. O'Beirne states,
indeed, that he has frequently examined the rectum at the
moment when a moderate inclination to go to stool is felt, and
found it empty and contracted.2 But in cases where the faeces

1 O'BEIRNE, op. cit., p. 12.

2 O'Beirne apparently fails to make a sufficiently accurate distinction between
"a moderate inclination to goto stool" (Op. cit., p. 12) and the peculiar sensation
which seems to demand a prompt evacuation. This latter we beh'eve to be due to
the presence of faecal matter in the rectum.

408 DIGESTION.

are very fluid, or when the call for an evacuation has not been
regarded and has become imperative, the immediate dis-
charge of matters when the sphincter is relaxed shows that
the rectum has been more or less distended. In many per-
sons of constipated habit, and particularly in old subjects, the
rectum may become the seat of large accumulations of hard-
ened and impacted faeces ; but this is a pathological condition.

The sensation which ordinarily precedes and gives rise to
evacuation of faecal matter is peculiar, and very variable in
intensity. When this sensation is well marked but not ex-
cessive, it is probably due to the presence of fascal matter in
the rectum, not in sufficient quantity, however, to press for-
cibly on the sphincter. Pressure upon the rectum from any
cause, or irritation of its mucous membrane, is apt to give
rise to this peculiar sensation to a very marked degree. In
some diseases, the exaggeration of this sensation, then called
tenesmus, is very distressing.

In the process of defecation, the first act is the passage,
by peristaltic contractions, of the contents of the sigmoid
flexure of the colon through the slightly constricted opening
of the rectum into its dilated portion below. The fsecal mat-
ter, however, is not allowed to remain in this situation, but
passes into the lower portion of the rectum, in obedience to
the contractions of its muscular coat, assisted by the action
of the abdominal muscles and diaphragm. The circular fibres
of the rectum undergo the ordinary peristaltic contraction ;
and the action of the longitudinal fibres is to render the rec-
tum shorter and more nearly straight. The internal and the
external sphincter present a certain amount of resistance to
the discharge of the faeces, more particularly the external
sphincter, which is a striated muscle of considerable power.
There is always, however, a voluntary relaxation of this mus-
cle, or rather a cessation of its semi-voluntary contraction,
which immediately precedes the expulsive act. The dila-
tation of the anus is also facilitated by the action of the
levator ani, which arises from the posterior surface of the

DEFECATION. 409

body and ramus of the pubis, the inner surface of the spine
of the ischium, and a line of fascia between these two points,
passes downward and is inserted into the median raphe of the
perineum and the sides of the rectum, the fibres uniting with
those of the sphincter. While this muscle forms a support
for the pelvic organs during the act of straining, it steadies
the end of the rectum, and by its contractions, favors the re-
laxation of the sphincter, and draws the anus forward.

The action of the diaphragm and the abdominal muscles is
very simple. They merely compress the abdominal organs
and consequently those contained in the pelvis, and assist in
the expulsion of the contents of the rectum. The diaphragm
is the most important of the voluntary muscles concerned in
this process ; and during the act of straining, the lungs are
moderately filled and respiration is interrupted. The vigor
of these efforts depends greatly upon the consistence of the
faecal mass, very violent contractions being frequently required
for the expulsion of hardened faeces after long constipation.
Though more or less straining generally takes place, the con-
tractions of the muscular coats of the rectum are frequently
competent of themselves to expel the fasces, especially when
they are soft. This can be shown by arresting all voluntary
muscular action during an easy act of defecation, when the
fasces may be passed by contractions of the rectum alone.

By a combination of the movements above described, the
floor of the perineum is pressed outward, the anus is di-
lated, the sharp bend in the lower part of the rectum is
brought more into line with the rest of the canal, and a por-
tion of the contents of the rectum is expelled. Yery soon,
however, the passage of faeces is interrupted by a contraction
of the levator ani and the sphincter, by which the anus is
suddenly and rather forcibly retracted. This muscular
action may be effected voluntarily ; but after the sphincter
has been dilated for a time, the evacuation is interrupted in
this way, notwithstanding all efforts to oppose it. After a
time, another portion of faeces is discharged, until the matters

410 DIGESTION.

have ceased to pass out of the sigmoid flexure, and the rec-
tum has been emptied. The mucous membrane of the rec-
tum, which is rather loosely held to the subjacent tissue, is
slightly prolapsed during an evacuation, but returns shortly
after the act has been completed.

Yery little need be said concerning the influence of the
nervous system on the movements concerned in defecation.
The non-striated muscular fibres which form the muscular
coat of the rectum are supplied with nerves from the sympa-
thetic system ; and to the external sphincter are distributed
filaments from the last sacral pair of the spinal nerves. These
nerves bring the sphincter to a certain degree under the con-
trol of the will, and impart likewise the property of tonic
contraction, by which the anus is kept constantly closed.

Gases found in the Alimentary Canal.

In the human subject, a certain quantity of gas is gener-
ally found in the stomach and in the small and the large
intestine. The most accurate analyses of these gases, as
they may be supposed to exist in the human subject in
health, are those of Magendie and Chevreul, who had the
opportunity of examining the bodies of several criminals
immediately after execution. The previous analyses by Ju-
rine (who was the first to examine the gases of the alimentary
canal) and others, were made before the processes for the
analysis of gases had been brought to a sufficient degree of
perfection to insure accurate results.

The gases in the stomach appear to have no definite func-
tion. They generally exist in very minute quantity, and are
sometimes absent. The oxygen and nitrogen are derived
from the little bubbles of air which are incorporated with
the alimentary bolus during mastication and insalivation.
The other gases are probably evolved from the food during
digestion ; at least, there is no satisfactory evidence that they
are produced in any other way.

Yery little gas is ordinarily found in the stomach. Ma-

. GASES FOUND IN THE ALIMENTARY CANAL. 411

gendie and Chevreul collected and analyzed a small quantity
from the stomach of an executed criminal a short time after
death, and ascertained that it had the following compo-
sition : 1

Gases contained in the Stomach.

Oxygen 11-00

Carbonic Acid • 14-00

Pure Hydrogen 3-55

Nitrogen 71*45

100-00

Magendie and Chevreul found three different gases in the
small intestine. Their examinations were made upon three
criminals soon after execution. The first was twenty-four
years of age, and two hours before execution had eaten bread
and Gruyere cheese and drunk red wine and water. The
second, who was executed at the1 same time, was twenty-
three years of age, and the conditions as regards digestion
were the same. The third was twenty-eight years of age,
and four hours before death, he ate bread, beef, and lentils,
and drank red wine and water. The following was the re-
sult of the analyses.2

(rases contained in the Small Intestine.

First Criminal Second Criminal. Third Criminal.

Carbonic acid 24-39 40*00 25-00

Pure Hydrogen 55-53 51-15 8-40

Nitrogen 20-08 8'85 66*60

100-00 100-00 100-00

No oxygen was found in either of the examinations, and
the quantities of the other gases were so variable as to lead to
the supposition that their proportion is not at all definite.
"We have already alluded to the mechanical function of these
gases in intestinal digestion.3

1 MAGENDIE, Prtcis tflementaire de Physiologic, Paris, 1836, tome ii., p. 89.
3 Ibid., p. 115.
3 See page 379.

412

DIGESTION.

In the large intestine, the constitution of the gases pre-
sented the same variability as in the small intestine. Car-
buretted hydrogen was found in all of the analyses. In the
large intestine of the first criminal, and in the rectum of the
third, were found traces of sulphuretted hydrogen. The fol-
lowing is the result of the analyses in the cases before cited.
In the third, the gaseous contents of the caecum and the rec-
tum were analyzed separately.1

Gases contained in the Large Intestine.

First Criminal.

Second Criminal.

Third Criminal.

Third Criminal.

Carbonic Acid 2
Carburetted hydrogen
and traces of sul-
phuretted hydrogen
Pure hydrogen and
carburetted hydro-
gen

43-50
5-47

70-00
11-60

Caecum.

12-50

Rectum.

42-86
11-18

Pure hydrogen
Carburetted hydrogen

5*1-03

18-40

7-50
12-50
67-50

45-96

100-00

100-00

100-00

100-00

Origin of the Intestinal Gases. — With our present infor-
mation on this subject, the most reasonable view to take of
the source of the gases normally found in the intestines is
that they are given off from the articles of food in their
various stages of digestion and decomposition. That this is
the principal source of the intestinal gases there can be no
doubt ; and it is well known that certain articles of food, par-
ticularly vegetables, generate much more gas than others.
The principal gases found in the intestinal canal may all be
obtained from the food ; while some of them, as hydrogen
and carburetted hydrogen, do not exist in the blood ; and it
is difficult to conceive how they can be generated in the in-

1 HAGENDIE, op. cit., p. 128.

a In this examination, "traces of sulphuretted hydrogen were manifested upon
the mercury before the instant when the gas was analyzed ; " (op. cit, p. 129).

OBIGIN OF THE INTESTINAL GASES. 413

testine except by decomposition of some of the articles of
food. Hydrogen and its compounds are always found in
quantity in the small and the large intestine. Chevillot,
who made a number of researches into the composition of
the gases of the alimentary canal in patients dead from dif-
ferent diseases, submitted various alimentary substances
taken from the digestive organs to a temperature equal to
that of the body. In a certain number of instances, but not
in all, hydrogen was evolved.1

It is said that gas is sometimes found in the intestines
of the foetus, and that it may be generated in a loop of intes-
tine in a living animal, after a portion of the canal has been
drawn out, isolated by ligature, freed from its liquid and
gaseous contents, and returned to the abdomen. In some
diseased conditions also, it is very common for the abdomen
to become rapidly tympanitic, the gas being generated so
quickly that its presence is not easily explained by supposing
it to be evolved by decomposition of the ingesta. It has, in-
deed, been supposed that the intestinal mucous membrane is
capable of secreting gases as well as liquids ; but in support
of this view there does not appear to be any positive demon-
stration. No doubt some of the gases which may be formed
in the intestine are capable of absorption. It is impossible
to say, however, that even the gases normally held in solu-
tion in the blood, namely, oxygen, nitrogen, and carbonic
acid, are exhaled from the blood into the intestinal cavity.
Oxygen is never given off in this way, for this gas has only

1 CHEVILLOT, Recherches sur les Qaz de VEstomac et des Intestins de THomme
d Veldt de maladie. — Journal de Physiologic, Paris, 1829, tome ix., p. 310.
Magendie (Precis filementaire de Physiologic, Paris, 1836, p. 117) states that
Chevillot collected the contents of the small intestine, which he allowed to fer-
ment for a certain time at the temperature of the body, obtaining exactly the
same gases which were found in the intestine. The reference to the paper of
Chevillot is given above, and it is there simply stated that hydrogen is sometimes
given off from the contents of the small intestine. Chevillot proposed at some
future time to give the full results cf his experiments on this subject, but as far
as we know, this has never been done.

414: DIGESTION.

been found in the stomach, and is there derived from air
which has been swallowed. "With regard to the origin of
the other gases found in the intestine under the peculiar
circumstances just mentioned, in which they are apparently
generated with much rapidity, there are not sufficient data
to enable us to form an intelligent opinion.

CHAPTER XT.

ABSORPTION.

General considerations — Absorption by blood-vessels — Absorption by lacteal and
lymphatic vessels — Physiological anatomy of the lacteal and lymphatic sys-
tem— Thoracic duct — Structure of the lacteal and lymphatic vessels — Lym-
phatic glands — Absorption of albuminoids by the lacteals — Absorption of
glucose and salts by the lacteals — Absorption of water by the lacteals — Ab-
sorption from parts not connected with the digestive system — Absorption
from the skin — Absorption from the respiratory surface — Absorption from
closed cavities, reservoirs of glands, etc. — Absorption of fats and insoluble
substances — Variations and modifications of absorption — Influence of the
condition of the blood and the vessels on absorption — Influence of the ner-
vous system on absorption.

DIGESTION has two great objects : one is to reduce the
different alimentary principles to a fluid condition, and the
other to commence the series of catalytic transformations by
which these principles are rendered capable of nourishing
the organism. The principles thus acted upon are taken
into the blood as fast as the requisite changes in their consti-
tution are effected ; and once received into the circulation,
become part of the great nutritive fluid, supplying the waste
which the constant regeneration of the tissues from materials
furnished by the blood necessarily involves. The only group
of principles which does not obey this general law is the
fats. Though a small portion of the fat taken as food passes
directly into the blood-vessels of the intestinal canal, by far
the greatest part finds its way into the circulation by means
of special absorbent vessels which empty into large veins.
In whatever way fat enters the blood, it is never dissolved,
but is reduced to the condition of a fine emulsion.

416 ABSORPTION.

The process by which digested materials are taken into
the blood is called absorption. It is now recognized that two
sets of vessels are concerned in the performance of this func-
tion ; namely, the blood-vessels and the lacteals. Those parts
of the food which have been rendered fluid and are capable
of forming a homogeneous mixture with the blood-plasma
are absorbed chiefly by the blood-vessels, though a small
portion finds its way into the lacteals. The emulsified fats
are taken up in greatest part by the lacteals, though a small
quantity is taken directly into the blood. In treating of
this subject, it will be convenient to consider the action of
these two kinds of vessels separately.

Absorption ty Blood - Vessels.

That soluble substances can pass through the delicate
walls of the capillaries and small veins and that absorption
actually takes place in great part by blood-vessels is a fact
which hardly demands discussion at the present day. There
are now all the proofs that could be asked in support of
this view. Soluble principles which have disappeared from
the alimentary canal have been repeatedly found in the blood
coming from the part, even when the lymphatics have been
divided and communication existed only through the blood-
vessels. The old theoretical view which was entertained be-
fore the lymphatics and lacteals were discovered was that
absorption took place by blood-vessels ; but after special ab-
sorbent vessels were described, it was generally supposed
that they furnished the only avenue for the entrance of new
matters into the economy, though the doctrine of vascular
absorption was retained by a few.1 It was only after the

1 The observations of William and John Hunter, who attempted to show by
experiments upon living animals that the lacteals were the only absorbent ves-
sels of the intestines, have been so completely disproved by more recent investi-
gations that they do not demand extended discussion. These experimenters
showed that milk introduced into the intestinal cavity was absorbed by the lac-
teals and not by the veins ; but the evidence that absorption of other fluids did
not take place by the veins was entirely insufficient. The experiments referred

ABSORPTION BY BLOOD-YESSELS. 417

conclusive experiments of Magendie, in 1809, tnat positive
proof was given of the absorbing power of the blood-vessels.
These experiments settled the question of vascular absorp-
tion, though they led some to take too exclusive a view of
the importance of the venous radicles in this function, and
to deny that absorption took place to any considerable ex-
tent through the lymphatic and lacteal system.

If it were consistent with the plan of this work to enter
into a purely historical discussion of the theories which have
been advanced from time to time concerning the mechanism
of absorption, it might be shown that comparatively modern
researches have led us back to the views entertained by the
ancients, before the discovery of the lymphatic system of
vessels ; but we shall confine ourselves to a history of those
facts connected with absorption, which have been experimen-
tally demonstrated. In 1808, in a paper on the " Structure
and Uses of the Spleen," read before the Royal Society of
London, Everard Home showed that various matters in-
jected into the stomach were carried to the spleen without
passing into the thoracic duct. The inference to be drawn
from this paper, which is very brief, is that he supposed that
these substances were carried to the spleen by absorbents,
and were there mixed with the blood. In these experiments
Home was assisted by Brodie.1 In 1811, as the result of
further experiments on this subject, Home abandoned the
idea that the -principles absorbed were mixed with the blood
in the spleen, as he found that matters injected into the
stomach appeared in the blood in a dog from which the
spleen had been removed four days before.2 The first

to were made in 1758 and 1759. (J. HUNTER, Observations on Certain Parts of
the Animal (Economy, Philadelphia, 1840, p. 303.)

1 HOME, On the Structure and Uses of the Spleen. — Philosophical Transac-
tions, London, 1808, p. 45 et seq.

2 HOME, Experiments to prove that Fluids pass directly from the Stomach to
the Circulation of the Blood, and from thence into the Cells of the Spleen, the G-all-
Bladder and Urinary Bladder without going through the Thoracic Duct. — Philo-
sophical Transactions, London, 1811, p. 163 et seq.

27

4:18 ABSORPTION.

of these essays contained very little concerning the general
process of absorption from the alimentary canal, but was
supposed to throw some light upon the function of the
spleen, as an organ in which part of the chyle was mixed
with the blood. The second essay was published two years
after the researches of Magendie had been communicated to
the Institute of France.

The results of the experiments of Magendie were of the
most positive character.1 In his first experiments, it was
found that after ligation of the thoracic duct in dogs, poison-
ing by a solution of upas introduced into the peritoneal cavity,
the pleural cavity, the stomach, intestines, or muscles of the
thigh, took place with no diminution in intensity or rapidity.
The second series of experiments was even more striking. The
abdomen of a dog, that had eaten largely seven hours before,
was opened, and a loop of the small intestine drawn out.
About fifteen inches of the canal was separated from the rest
by two ligatures, and finally cut off beyond them. The lym-
phatics arising from the isolated portion of the intestine,
which were very apparent, were all tied with two ligatures,
and divided between them. Five mesenteric arteries and
five veins then remained connecting the intestine with the
vascular system. Four of the arteries and veins were ligated
and divided ; 'and the single artery and vein which remained
were isolated for about two inches of their length, and even
the cellular coat dissected off, for fear that it might be said to
contain lymphatics. A small quantity of upas was then in-
troduced into the isolated portion of the intestine (which had
no communication with the body except by the single mesen-
teric artery and vein), the loop was enveloped in a fine cloth
and returned to the abdominal cavity. In about six minutes,
the general effects of the poison were manifested with their
usual intensity. This experiment was repeated several times,

1 MAGENDIE, Memoire sur les Organes de I1 Absorption chez les Mammiferes ;
lu d I'lnstilut le 7 aout, 1809. — Journal de Physiologic, Paris, 1821, tome i., p.
18 et seq.

ABSORPTION BY BLOOD-VESSELS. 419

with the game result. In other experiments, the leg was sep-
arated from an animal, all the parts being divided except the
crural artery and vein ; and in one experiment, a quill was
introduced into each of these vessels, secured with ligatures,
and the vessels themselves divided, so that there could be no
communication of the leg with the body except through the
circulating blood. Under these conditions, the poison intro-
duced into the foot produced its effects upon the system in
ordinary time ; while it was found that the effects of the
poison could be retarded or arrested by simple compression
of the vein. These experiments, which are models of inge-
nuity and accuracy, removed all doubt of the fact that ab-
sorption takes place by blood-vessels.

Most of the experiments which followed those of Magen-
die simply confirmed his results. Tiedemann and Gmelin, as
the result of a very elaborate series of investigations, showed
that alimentary matters, odorous and coloring matters, and
various saline and metallic substances, when taken into the
alimentary canal, find their way into the system by the ab-
sorbents and the thoracic duct, and by the radicles of the por-
tal vein.1 Finally, Segalas, in 1822, supplied about the only
link wanting in the chain of evidence developed by the origi-
nal experiments of Magendie. He demonstrated that poi-
soning did not follow the introduction of a solution of nux
vomica into a loop of intestine separated from the rest of the
canal, so long as the circulation was interrupted, or when the
blood returning from the part by the vein was discharged
from the vessel and not carried into the general circulation.2

At this time the subject of vascular absorption attracted
a great deal of attention among experimental physiologists ;
and a committee, consisting of Drs. Harlan, Lawrence, and

1 TIEDEMANN ET GMELIN, JRecherches sur la Route qui prennent diverses Sub-
stances pour passer de VEstomac et du Canal Intestinal dans le Sang ; sur la
Fonction de la Rate et sur Us Voies cachees de V Urine, Trad, par S. Heller, Paris,
1821.

2 SEGALAS, Note sur F Absorption Intestinale. — Journal de Physiologic, Paris,
1822, tome ii., p. 117 ft scq.

420 ABSORPTION.

Coates, was appointed by the Academy of Medicine, of Phil-
adelphia, to examine into the subject. This committee made
a great number of experiments, which entirely confirmed the
observations of Magendie.1 The same may be said of the
experiments of Panizza, which were, indeed, as regards in-
testinal absorption, little -more than a' repetition of those of
Magendie and Segal as.2 At the present day there is no dif-
ference of opinion among physiologists concerning the direct
absorption of nutritive matters by the blood-vessels of the
alimentary canal. It has been repeatedly shown, indeed,
that during absorption, the blood of the portal vein is rich in
albuminoids, sugar, and other principles resulting from
digestion.

In the mouth and oesophagus, the sojourn of alimentary
principles is so brief, and the changes which they undergo so
slight, that no absorption of any moment can take place. It
is evident, however, that the mucous membrane of the mouth
is capable of absorbing certain soluble matters, from the effects
which are constantly observed when the smoke or the juice
of tobacco is retained in the mouth even for a short time.
In the stomach, however, the absorption of certain materials
takes place with great activity. A large proportion of the in-
gested liquids,3 and of those principles of food which are dis-

1 Report of the Committee of the Academy of Medicine of Philadelphia, on
the means by which Absorption is effected. — Philadelphia Journal of the Medical
and Physical Sciences, 1821, vol. iii., p. 273, and 1822, vol. v., p. 327.

2 PANIZZA, De V Absorption Veineuse, Paris, 1843. The most striking of the
experiments of Panizza was one made on a horse, in which a loop of the small
intestine was drawn out, isolated by ligatures, and left connected with the sys-
tem only by a single artery and vein. Poisons and other substances introduced
into this loop were detected in blood taken from the vein, and their effects upon
the system were not manifested so long as the blood coming from the part was
prevented from entering the general circulation. (Op. cit., p. 19.)

8 It has been repeatedly demonstrated by experiments that liquids are ab-
sorbed from the stomach after the pylorus has been tied. This has been done
by Magendie '(Precis Elemcntaire de Physiologic, Paris, 1836, tome ii., p. 140),
by Bouchardat and Sandras, and others. The experiments made by Colin
and Bouley on absorption from the stomach after ligation of the pylorus in

ABSORPTION BY BLOOD-VESSELS. 4-21

solved by the gastric juice and converted into albuminose, is
taken up directly by the blood-vessels of the stomach. It
may, indeed, be assumed as a general law, that digested mat-
ters are in great part absorbed as soon as their transforma-
tions in the alimentary canal have been completed.

In the passage of the food down the intestinal canal, as
we have already seen, there is a constant loss of material.
As the digestion of the albuminoids is completed, these prin-
ciples are absorbed, and their passage into the mass of blood
is indicated chiefly by an increase in its proportion of al-
bumen. Analyses by Beclard of blood taken from the portal
veins during digestion have shown a great increase in the pro-
portion of fibrin over the blood in other parts of the venous
system and in the same vessel during the intervals of diges-
tion.1 These observations have been repeatedly confirmed, and
many of the other products of digestion, such as glucose and
fatty emulsion, have also been demonstrated in quantity in the
blood of the portal vein during absorption. The fats, though
taken up in greatest part by the lacteals, are always found in
greater or less quantity in the portal blood. It has fre-
quently been observed that after a full meal consisting
largely of fat, the blood from the portal vein, as it cools and
coagulates, leaves a white scum of fat upon the surface.2 On
one occasion we observed in the portal blood of an animal
killed in full digestion a layer of fat on cooling so thick that
a quantity of blood, which was spilled upon a table and the

different animals show that in the earnivora, and in most animals with a single
stomach, this takes place with great rapidity. In the horse, the mucous mem-
brane of a great portion of the stomach is lined by pavement epithelium like that
found in the oesophagus, and absorption from the stomach is very slow. (COLIN,
Traite de Physiologic Comparie, Paris, 1856, tome ii., p. 29 et seq.

1 BECLARD, Recherches Experimentales sur les Fondions de la Rate etsur celles
de la Vcine Porte. — Archives Generates de Medecine, Paris, 1848, p. 443.

2 Bernard found in the dog that the portal blood sometimes contained almost
as much fatty emulsion as the chyle (Du Role de VAppareil Chyli/ere dans I* Ab-
sorption des Substances Alimentaires}. — Comptes Rendus, Paris, 1850, tome xxxi.,
p. 802.

422 ABSORPTION.

floor, was white, like milk. We have since frequently at-
tempted to demonstrate this excessively chylous condition
of the blood during the absorption of fats, but have found
that it is not generally so well marked.

The greatest part of the food is absorbed by the intesti-
nal mucous membrane, and, with the alimentary substances
proper, a large quantity of secreted fluid is reabsorbed. This
fact is particularly striking as regards the bile. The biliary
salts disappear as the alimentary mass passes down the intes-
tine and are undoubtedly absorbed, though they are so
changed that they cannot be detected in the blood by the
ordinary tests. In this portion of the alimentary canal, it
will be remembered that an immense absorbing surface is

O

provided, by the arrangement of the mucous membrane in
folds, forming the valvulso conniventes, and the presence of
the innumerable villi which are found throughout the small
intestine. A certain portion of the gaseous contents of the
intestines is also absorbed, though it is not easily ascertained
what particular gases are thus taken up.1

Absorption by Lacteal and Lymphatic Vessels.

The history of the discovery of what is ordinarily termed
the absorbent system of vessels, from the vague allusions of
Hippocrates, Galen, Aristotle, and others, to the description
of the thoracic duct in the middle of the sixteenth century
by Eustachius,2 and finally to the discovery of the lacteals
by Asellius, in 1622, is more interesting in an anatomical,

1 In treating of digestion, we have necessarily considered the complete prepara-
tion of alimentary principles for absorption, and have frequently alluded to the
fact that these principles are taken up as fast as they are thus modified. In con-
nection with the subject of absorption, therefore, it will be only necessary to point
out the vessels which are concerned in this function, and the mechanism of the
passage of liquids through their walls.

2 BARTHOLOMEWS EUSTACHIUS, De Vena quce Azygos Greeds dicilur, etc. ( Opus-
<wla Anatomica, Yenetiis, 1564, p. 301). Eustachius discovered in the horse a ves-
sel beginning at the left jugular vein and descending toward the pillars of the
diaphragm, which he described as " always white, and filled with watery humor."
This was the thoracic duct.

ABSORPTION BY LACTEAL AND LYMPHATIC VESSELS. 423

than in a physiological point of view. Our knowledge of
the anatomy of the absorbent system dates from the discov-
ery of the thoracic duct; but from the discovery of the lac-
teals, dates the history of these vessels as the carriers of
nutritive matters from the intestinal canal to the general
system.

In 1622, in making an experiment on a dog for the pur-
pose of demonstrating to some scientific friends certain points
connected with the functions of the recurrent laryngeal
nerves, Asellius opened the abdomen and saw for the first
time little white vessels passing back from the intestine
between the folds of the mesentery. Not knowing at first
the nature of these vessels, he punctured one of them, and
the milky fluid escaped, revealing their true character.1
The discovery of the lacteal system was thus made appar-
ently by pure accident. The entire history of this discovery
is given by its author. He states that when the dog died,
the white vessels disappeared from before his eyes. The fol-
lowing day, on opening the abdomen of another dog, he
found no lacteals ; but remembering that the first animal
had been experimented upon while in full digestion, he ex-
posed the abdominal organs in another dog under the same
conditions, and again found the vessels full of chyle. His
observations upon dogs were afterward confirmed by experi-
ments upon cats, sheep, and many other animals. Asellius
died in 1626, and it was reserved for others to complete his
discovery by showing the true course of the lacteals ; he
supposing that they passed directly to the liver, where the
chyle was made into blood. His* work, De Lactibus sive
Lacteis Venis, was published in 1628,2 by Tadinus and Sep-

1 GASPAR ASELLIUS, De Ladibus sive Lacteis Venis, etc., Basilese, Typis Henric-
Petrinis, 1628, p. 19 et seq.

*'J The copy of Asellius in our possession was published by Alexander Tadinus
and Senator Septalius, and bears the date of 1628. Reference to the same work,
published in 1627, at Mediol, is made by Berard ( Cours dc Physiologic, Paris,
1849, tome ii., p. 563).

4:24: ABSORPTION.

talius, two of his friends who were present at his first demon
stration.1

Like many great discoveries, the demonstration of the
lacteals was denied by several of the prominent physiologists
of the day. Among others, Harvey is frequently quoted as
refusing to recognize the claims of Asellius ; a want of
appreciation of the claims of another to an important dis
co very, which might justly be regarded as ungenerous in so
great a discoverer, and one who suffered so keenly from si in
ilar opposition. "We do not find, however, that this subject
is discussed to any extent in the systematic works of Harvey ;
but it is mentioned in letters written during the later periods
of his life. In one of these, addressed to Dr. Morison, of
Paris, in 1652, in speaking of the discovery by Asellius and
the later discovery of the connection between the lacteals
and the thoracic duct by Pecquet, Harvey, while admitting
the existence of the vessels, does not acknowledge that they
carry the chyle from the intestine.2 In another letter, writ-
ten in 1655, he excuses himself from investigating the sub-
ject of the use of these vessels on account of his advanced
age, " which unfits us for the investigation of novel subtleties,
and the mind which inclines to repose after the fatigue of
lengthened labors." 3 At the time when the first letter was
written, Harvey was seventy-four years of age, and he was
seventy-seven at the date of the second letter. The positive
proof of the connection of the lacteals with the thoracic duct
was only published in 1651, and. the work reached Harvey
just before the letter to Dr. Morison was written. It is not
to be expected that H^vey would at that time attempt

1 It is stated by Breschet that in 1628, the lacteals were seen for the first
time in the human subject. The body of a criminal, who had made a copious
repast before his execution, was given by Peiresc, senator of Aix, to Gassendi,
and some physicians of his acquaintance, who made an examination an hour and
a half after death and found the vessels full of chyle. (BRESCHET, Systeme Lym-
phaiique, Paris, 1836, p. 4.)

2 HARVEY, Works, Sydenham edition, London, 1847, p. 604
? Ibid., p. 613 et seq.

ABSORPTION BY LACTEAL AND LYMPHATIC VESSELS. 425

with all the ardor of youth, to verify new experiments, and
his disinclination to do so should not be regarded, as it seems
to be by some, as a blot upon his reputation.

In 1649,1 Pequet discovered the receptaculum chyli, and
demonstrated that the lacteals did not pass to the liver, but
emptied the chyle into the commencement of the thoracic
duct, by which it was finally conveyed into the venous sys-
tem.1 In 1650-'51, the anatomical history of the absorbent
vessels was completed by the discovery, by Rudbeck, of vessels
carrying a colorless fluid, in the liver, and finally in almost
all parts of the body. Rudbeck demonstrated the anatomi-
cal identity of these vessels with the lacteals.3 They were
afterward carefully studied by Bartholinus, who gave them
the name of lymphatics.4

It is unnecessary to follow out the various researches
made into the structure of the lymphatics in man and the
inferior animals by the Hunters, Hewson, Monro, Cruik-

1 1649 is given by Haller as the date of this discovery (Elementa Physiologies,
Bernse, 1765, tomus vii., p. 203). Some authors state that the discovery was
made in 1647, and others in 1648. The original work of Pequet was published
in 1651. He does not himself give the date of the discovery, though he states
that the investigations which formed the basis of his work occupied three years.

a J. PEQUETUS, JSxperimenta nova Anatomica, etc., in the BiUiotheca Anatomi-
ca by CLERICUS and MANGETUS, Genevse, 1699, tomus il, p. 689 eiseq.

3 OLAUS RUDBECK, Nova JExercitatio Anatomica, exhibens Ductus Hepalicos
Aquosos et Vasa Glandularum Serosa, in the BiUiotheca Anatomica, tomus ii., p.
729 et seq.

4 BARTHOLINUS, Vasorum Lymphaticorum Historia nova, in the Bibliotheca
Anatomica, tomus ii., p. 722. The honor of the discovery of the lymphatics is
by some claimed for Bartholinus. His observations, however, were made in
1651-'52, while those of Rudbeck were made in 1650-51.

Some authors have advanced the claims of Dr. Jolyffe, an English anat-
omist, to the discovery of the lymphatics. In Cruikshank's elaborate work
(The Anatomy of the Absorbing Vessels in Man, second edition, London, . 1790,
p. 36), it is stated that in 1653, Dr. Jolyffe, who was then taking his degree at
Cambridge, informed Glisson that he had discovered a fourth variety of vessels,
different from the veins, arteries, and nerves. This was two years later than the
discovery of these vessels by Rudbeck ; and it is evident that Jolyffe, who made
no publication of his observations at the time, has no claim to priority, though
he may have been ignorant of the observations of his predecessors.

426 ABSORPTION.

shank, and others. Though these vessels are very delicate
and difficult of study, it is now pretty generally admitted that
they have no orifices at their origin in the intestines and other
parts, but are perfectly closed, and all substances which
are absorbed by them enter by imbibition. The old idea,
which dates from the discoveries of Asellius and Pecquet,
that the lacteals absorb all the products of digestion, was
overthrown by the experiments of Magendie, and of those
who experimented : after him on vascular absorption. It is
now known that the fatty portions of the food, reduced to a
very fine emulsion by the pancreatic juice, are absorbed by
this system of vessels, and that these are the only principles
which are taken up in great quantity. The arguments which
we have already mentioned are sufficient to establish this
fact. If the abdomen of a living animal be opened during full
digestion, then, and then only, will the lacteals and the
thoracic duct be found distended with fatty emulsion. If the
organ which digests fat be rendered incapable of performing its
function, the lacteals cease to carry chyle. These vessels do not
appear in the mesentery until the food has passed the orifice of
the pancreatic duct. Finally, the observations of Bouchardat
and Sandras remove all doubt as to the absorption of the pro-
ducts of the digestion of fatty matters by the lacteals ; for these
observers found not only that in dogs the proportion of fat in
the chyle was increased pari passu with an increase in the
quantity of fat taken as food, but that the particular kinds of
fat administered to the animals could be recognized in the
chyle.1 We have seen that a certain quantity of fat escapes
the lacteals and is absorbed directly by the blood-vessels ; and
it becomes an important question to determine whether the
lacteals, in addition to their more prominent function, be not
concerned in the absorption of drinks, the albuminoids, saline
and saccharine matters, etc. This question will be taken up

1 BOUCHARDAT ET SANDRAS, Recherches^ur la Digestion ct P Assimilation den
Corps gras. — Anmiaire de Therapeutique, Paris, 1845, p. 242 et scg.

ANATOMY OF THE LACTEAL AND LYMPHATIC SYSTEM. 427

after the consideration of certain points in the anatomy of
the lymphatic system.1

Physiological Anatomy of the Lacteal and Lymphatic
System. — One of the most difficult problems in anatomy is
to determine the situation and mode of origin of the lymphat-
ics in different parts of the body. The tenuity of the walls
of these vessels, even in their course, and the presence of in-
numerable valves, render it impossible to study them by the
ordinary methods of injection. Since it has been ascertained,
however, that they originate in many parts by a rich anas-
tamosing plexns, their anatomy has been well made out in
certain situations by simply puncturing with a fine-pointed
canula the parts in which the plexus is supposed to exist, and
allowing a fluid, generally mercury, to gently diffuse itself in
the vessels of origin. Following the course of the vessels,
the fluid passes into the larger trunks, and thence to the lym-
phatic glands. The regularity of the plexus through which
the fluid is first diffused and the passage of the injection
through the larger vessels to the glands are positive proof
that the lymphatics have been penetrated, and that the ap-
pearances observed are not the result of mere infiltration.
This mode of investigation is best illustrated in the injection
of the lymphatics of the skin. The pressure employed is de-
rived simply from a column of mercury of sufficient height ;
the tube in which the mercury is contained being connected
with a flexible tube, by which the height may be readily in-

1 One of the most successful of the early investigators into the anatomy of
the lymphatic system was the great anatomist, Mascagni. He demonstrated the
capillary plexus of origin of these vessels in many of the tissues of the body,
but was led into the error, in some instances, of supposing that fluid simply ex-
travasated in the substance of the tissue was contained hi lymphatic vessels. He
has therefore described lymphatics in situations where they have not been de-
monstrated by more recent investigations. However, the figures which he gives
of these vessels are copied into many of the recent works on anatomy. (MAS-
CAGNI, Dei Vasi Linfatid. — Prodrcmo della Grande Analomia, Firenze, 1819,
pp. 3-54.)

428 ABSORPTION.

creased or diminished at will. With, the flexible tube is con-
nected the capillary tube of glass, which is to be introduced
into the part to be injected. In the case of the skin, the fine
glass point is introduced just below the cuticle at so acute an
angle as to be almost horizontal. A stop-cock, which is con-
nected with a tube into which the glass point is fitted, is then
turned, and the pressure of the column of mercury forces in
the injection. The puncture in the skin is to be very super-
ficial, otherwise the mercury will pass into the blood-vessels.
"When the operation has been successful, the mercury will be
seen to " cover the skin with a silvery net-work." The tube
should remain in place for from half a minute to a minute
only. To demonstrate that this plexus really consists of
lymphatic vessels, one of 'them may be denuded and punc-
tured with the glass point, when the lymphatic will become
instantly distended as far as the nearest gland, in which the
injection is always arrested.1

Lymphatics have not been actually injected and demon-
strated in all the tissues of the body ; but in some parts in
which it has been thus far impossible to inject them, we are
not justified in assuming positively that they do not exist.
For example, in the intestinal villi, according to Sappey, these
vessels have never been seen, though their existence is al-
most certain. The most generally received views with regard
to the ordinary mode of origin of the lymphatic vessels is
that they commence by a closed capillary plexus, which does
not communicate with either the small arteries, veins, or the
capillary blood-vessels, and is always situated externally to
the blood-vessels. It does not appear that the vessels compos-
ing this plexus vary much in size. They are very elastic,
and after distension by injection, they return to a very small
diameter wThen the fluid is allowed to escape. It is prob-

1 For full details for the performance of these exceedingly delicate manipula-
tions, the reader is referred to the work of Sappey. ( Traite d'Analomie Descrip-
tive, Paris, 1853, tome i., p. 639 et seq.} This author has been peculiarly suc-
cessful in his researches into the minute anatomy of the lymphatic system.

ANATOMY OF THE LACTEAL AND LYMPHATIC SYSTEM. 429

Pig. 6.

able, therefore, that the capacity of the vessels is much ex-
aggerated by the means which are taken to render them
apparent. In some recent observations by Dr. Belaieff, of
St. Petersburg, into the origin of the lymphatics of the penis,
the walls of the vessels were rendered apparent by the action
of nitrate of silver in solution in pure water, and it is prob-
able that they were very little distended. The smallest of
these vessels had a diameter of about 3-^ °f an inch.1 This
may be taken as their average diameter in the primitive
plexus. This plexus, when the vessels are abundant, as they
are in certain parts of the cutaneous surface, resembles an
ordinary plexus of capillary blood-vessels, except that the
walls of the vessels are thinner and their diameter is greater.

In a recent work on
the lymphatic system, by
Dr. Labeda, which seems
to represent the latest
ideas of the French school,2
it is stated, on the author-
ity of Robin (whose ob-
servations are said to have
been confirmed by His),
that the vessels of ori-
gin of the lymphatic sys-
tem are always applied in
the form of a half-cylin-
der upon the capillary
blood-vessels " in such a
manner that the wall of
the capillary forms one
wall of the lymphatic:
they do not pass along the
veins, but along the arte-

1.1. Deep or subdermic net-work of lymphatics
of the skin. — 2.2.2.2. Vessels branching from
this net-work and applied to the internal face
of the integument, from which they soon ex-
tend and pass into the substance of the subcu-
taneous cellulo-aclipose layer. (SAPPEY, Manu-
el d' 'Anatomic Descriptive, Paris, 1847, tome
i, p. 593.)

1 BELAIEFF, Rcclierclies Microscopiques sur les Vaisseaux Lymphaiiques du
Gland. — Journal de I' Anatomic el dela Physiologie, Paris, 186G, tome iii., p. 469.

2 LABEDA, Sysfeme Lymphatique, Paris, 1866.

430 ABSORPTION.

rioles, and apply themselves indistinctly in the form of a
concentric demi-canal upon each capillary, then the lym-
phatic is detached little by little from the vessel which
it accompanies, and possesses a proper individuality (auto-
nomie) (Cours de CH. ROBIN)." x Robin alludes to this as
the general mode of origin of the lymphatics, and mentions
" the impossibility of capillary rupture or capillary exosmosis
without communication with the lymphatics when they ex-
ist." 3 But in a recent publication on the lymphatic system
of the torpedo, he describes this disposition of the lymphat-
ics around the small arteries, in fishes, reptiles, and batra-
chians, without applying it distinctly to the human subject.3
Robin has described a peculiar mode of origin in the lym-
phatics of the brain and spinal cord, which will be referred
to in connection with the mode of origin of the lymphatics
in particular parts.

In the general description of the lymphatic system, three
sets of vessels are usually recognized : the plexus situated on
the general surface ; the deep vessels ; and those coming from
the small intestine, ordinarily called lacteals.

The superficial vessels have the smallest diameter, and
are by far the most numerous. They are composed of the
fine plexus already mentioned, very superficially situated in
the skin, and a second plexus just below the skin, composed
of vessels of much greater diameter. The skin is thus en-
closed, as ifc were, between two plexuses of capillary lym-
phatics. A plexus analogous to the most superficial plexus
of the skin is found just beneath the surface of the mucous
membranes. These may, indeed, be classed with the super-
ficial lymphatics.

The deep lymphatics are much larger and less numerous,
and their origin is less easily made out. These accompany

1 LABEDA, op. cit., p. 27.

2 ROBIN, Programme du Cours d1 Histologie, Paris, 1864, p. 210.

3 ROBIN, Memoire sur V Anatomic des Lymphatiques des Torpilles. — Journal de
de V Anatomic et de la Physiologie, Paris, 1867, tome iv., p. 3 et seq.

ANATOMY OF THE LACTEAL AND LYMPHATIC SYSTEM. 431

the deeper veins in their course. They receive the lymph
from the superficial vessels.

!N"o valvular arrangement is found in the smallest lym-
phatics ; but the vessels coming from the primitive plexuses,
and the large vessels, contain valves in immense numbers.
These valves, being so closely set in the vessels, give to them,
when filled with injection, a peculiar and characteristic bead-
ed appearance.

The course of the lymphatics is generally tolerably direct.
As they pass toward the great trunks by which they com-
municate with the venous system, they present a peculiar
anastomosis with the adjacent vessels, called anastomosis by
bifurcation ; that is, as a vessel passes along with other ves-
sels nearly parallel with it, it bifurcates, and the two branches
pass into the nearest vessels on either side. These anasto-
moses are quite frequent and generally occur between vessels
of equal size. In their course, the vessels pass through the
lymphatic glands, which will be described further on.

A notable peculiarity in the lymphatic vessels is that they
vary very little in size, being nearly as large at the extremities
as they are near the trunk. In their course, they are always
much smaller than the veins and do not progressively enlarge
as they pass on to the great lymphatic trunks. The largest-
sized vessels as they pass from the skin are from ^ to ^ of
an inch in diameter,1 and the larger vessels, in their course,
have a diameter of from y^ to J of an inch.2 As in the case
of the smallest lymphatics in the primitive plexus, the elasti-
city of the walls of the vessels renders their calibre greatly
dependent upon the pressure of fluid in their interior. Many
anatomists have noticed that vessels hardly perceptible while
empty are capable of being dilated to the diameter of half
a line or more, returning to their original size as soon as the
distending fluid is removed.3

1 BELAIEFF, op. cit.

3 KOLLIKER, Manual of Human Miscroscopic Anatomy, London, 1860, p. 503.

a MILNE-EDWARDS, Lcfom sur la Physiologic, Paris, 1859, tome iv., p. 509, note.

432 ABSORPTION.

The peculiarities which the lymphatics present in the
different tissues and organs do not possess much physiolo-
gical interest, except the arrangement of the vessels of ori-
gin in the substance of the brain and spinal cord. In the
skin, the only interesting peculiarity which we have not al-
ready noticed is that the vessels appear to be very unequally
distributed in different parts of the surface. According to
Sappey,1 they are particularly abundant in the scalp over the
biparietal suture, the soles of the feet and the palms of the
hand, the fingers at the lateral portion of the last phalanges,
and the scrotum. In the median portion of the scrotum, they
attain their highest degree of development. They are also
found, though in fewer numbers, originating from around
the median line on the anterior and posterior surface of
the trunk ; the posterior median portion of the extremities ;
the skin over the mammae ; and around the orifices of the
mucous passages. Sappey has injected lymphatic vessels in
the anterior portion of the fore-arm, the thigh, and the leg,
and the middle portion of the face, though they are demon-
strated with difficulty in these situations. If they exist at
all in other portions of the cutaneous surface, they are few in
number and rudimentary.

In the mucous system, the lymphatics are very abundant.
Here are found, as in the skin, two distinct layers which en-
close between them the whole thickness of the mucous mem-
brane. The more superficial of these layers is composed of
a rich plexus of small vessels, and beneath the mucous mem-
brane is a plexus consisting of vessels of larger size and less
numerous. The superficial plexus is exceedingly rich in the
mixed structure which forms the lips and the glans penis, and
around the orifices of the mouth, the nares, the- vagina, and
the anus. There are certain mucous membranes in which the
lymphatics have never been injected. These are the mucous
membrane of the bronchial tubes, the membrane lining all
of the ducts of the glands except the ureters, the Schneide-

1 Op. dt.

ANATOMY OF. THE LACTEAL AND LYMPHATIC SYSTEM. 433

rian mucous membrane, and the conjunctiva. When an in-
jection has appeared to penetrate in these situations, it was
probably a mere infiltration of the parts, as the fluids never
have been made to enter the larger vessels, much less pass to
a lymphatic gland.1

In the visceral layer of the serous membranes, the lym-
phatics have been demonstrated in great abundance ; but here
they are supposed by Sappey to be derived from the organs
to which these membranes are adherent. Their existence in
the parietal portion of the membranes is doubtful ; and if
they exist here at all, their number is not great. Their ex-
istence in the synovial membranes is doubtful.

Lymphatics have been demonstrated as taking their origin
in the voluntary muscles, the diaphragm, the heart, and the
non-striated muscular coats of the hollow viscera, though
their investigation in these situations is exceedingly diffi-
cult.

Lymphatics are found coming from the lungs in immense
numbers. These arise in the walls of the air-cells, and sur-
round each pulmonary lobule with a close plexus. The deep
vessels follow the course of the bronchial tubes, passing
through the bronchial glands and the glands at the bifurca-
tion of the trachea, to empty into the thoracic duct and the
great lymphatic duct of the right side.

In the glandular system, including the ductless glands,
and in the ovaries, the lymphatic vessels are, as a rule, more
abundant than in any other parts of the body. They are
especially numerous in the testicle, the ovary, the liver, and
the kidney.

In the substance of the brain and spinal cord, Robin has
lately demonstrated a curious system of vessels which entirely
surround the capillary blood-vessels, and are connected with
the lymphatic trunks or reservoirs described by Fohmann
under the pia mater. The capillary blood-vessels thus float
in a fluid contained in these cylindrical sheaths, which

1 SAPPEY, op. cit., tome i., p. 595.
28

434: ABSORPTION.

exceed them in diameter by from jaVo- to T£7 of an inch
These investing vessels follow the blood-vessels in their rami
fications, and contain a clear fluid, with bodies resembling
the lymph-corpuscles. When Robin first described these ves-
sels minutely, he did not state definitely their physiological
relations ; * but he has just published a memoir in which he
describes them as true lymphatic vessels, analogous to the
lymphatics which partly surround the small blood-ves-
sels in fishes, reptiles, and batrachians.2 In these animals,
the lymphatics in many parts nearly surround the blood
vessels, to the walls of which the edges of their proper coat
are adherent ; and that portion of the wall of the blood-
vessel which is thus enclosed forms at the same time the wall
of the lymphatic.3 This disposition of the lymphatics in the
brain and spinal cord would allow of free interchange by
endosmosis and exosmosis of the liquid portions of the blood
and the lymph.

The following are the principal situations, in addition to
those already mentioned, in which lymphatic vessels have
never been satisfactorily demonstrated, and in which their
existence, even, is doubtful : the walls of the blood-vessels :
the osseous system; tendons, ligaments, and the general
fibrous system. It is almost unnecessary to add that they
are not found in the teeth, hair, nails, epidermis, and the
epithelial structures.

The lymphatic vessels from the superficial and deep por-
tions of the head and face on the right side, and those from

1 ROBIN, Recherches sur quelques Particularity de la Structure des Capillaires
de VEncephale. — Journal de la Physiologic, Paris, 1859, tome ii., p. 543 et seq.

2 ROBIN, Memoire sur V Anatomic des Lymphatiqucs des Torpilles. — Journal
de I1 Anatomic etde Physiologic, Paris, 1867, tome iv., p. 3 et seq.

3 The essential anatomical characters of the canals surrounding the blood-
vessels in the nervous centres were described by His, in 1865, probably without
a knowledge of the previous observations of Robin. (His, On the Existence of a
Perivascular Canal-System in the Central Organs of the Nervous System, and
upon its relations to the Lymphatic System. — British and Foreign Medico- Chirur-
gical Review, January, 1867, p. 237.)

ANATOMY OF THE LACTEAL AND LYMPHATIC SYSTEM. 435

the superficial and deep portions of the right arm, the right
half of the chest, and the mammary gland, with a few vessels
from the lungs, pass into the great lymphatic duct (ductus
lymphaticus dexter), which empties into the venous system
at the junction of the right subclavian with the internal
jugular. This vessel is about an inch in length and from
one-twelfth to one-eighth of an inch in diameter. It is pro-
vided with a pair of semilunar valves at its opening into
the veins, which effectually prevent the ingress of blood.

The vessels from the inferior extremities, and those from
the lower portions of the trunk, the pelvic viscera, and the
abdominal organs, generally pass into the thoracic duct. In
their course, all of the lymphatics pass through the small,
flattened, oval bodies, called the lymphatic glands, which are
so abundant in the groin, the axilla, the pelvis, and some
other parts. From two to six vessels, called the vasa affer-
entia, enter these bodies, having first broken up into a num-
ber of smaller vessels just before they pass in. They pass
out by a number of small vessels which unite to form one,
two, or three trunks, generally of larger size than the vasa
afferentia. The vessels which thus .emerge from the glands
are called vasa efferentia.

The lymphatics of the small intestine, called lacteals, pass
from the intestine between the folds of the mesentery to
empty, sometimes by one, and sometimes by four or five
trunks, into the receptaculum chyli. In their course, the
lacteals pass through several sets of lymphatic glands, which
are here called mesenteric glands.

The thoracic duct, into which the great majority of the
lymphatic vessels empty, is a vessel with exceedingly delicate
walls, and about the size of a goose-quill. It commences by a
dilatation more or less marked, called the receptaculum chyli.
This is situated upon the second lumbar vertebra. The canal
passes upward in the median line for the inferior half of its
length. It then inclines to the left side, forms a semicircu-
lar curve something like the arch of the aorta, and empties at

436 ABSORPTION.

the junction of the left subclavian with the internal jugular
vein. It diminishes in size from' the receptaculum to its mid-
dle portion, and becomes larger again near its termination.
It occasionally bifurcates near the middle of the thorax, but
the branches become reunited a short distance above. At
its opening into the venous system, there is generally a val-
vular fold, but, according to Sappey, this is not constant.1
There is always, however, a pair of semilunar valves in the
duct, from three-quarters of an inch to an inch from its
termination, which effectually prevent the entrance of blood
from the venous system.

It is now generally admitted that the lymphatic and lac-
teal vessels have no connection with the blood-vessels, except
by the two openings by which they discharge their contents
into the venous system. The foregoing sketch of the de-
scriptive anatomy of what has been called the absorbent
system of vessels shows that they may collect fluids, not only
from the intestinal canal during digestion, but from nearly
every tissue and organ in the body ; and that these fluids
are received into the venous circulation.

Structure of the Lacteal and Lymphatic Vessels. — The
lymphatic vessels, even those of largest size, are remarkable
for the delicacy and transparency of their walls. This is well
illustrated in the case of the lacteals, which are hardly visible
in the transparent mesentery, unless filled with opaque chyle.

From the difficulty in studying the lymphatics at their
origin, except by means of injections, or reagents which stain
the vessels, investigations into the structure of the smallest
vessels have been very few and not very satisfactory. It is
supposed, however, that the vessels here consist of a single
amorphous coat, resembling, in this regard, the capillary
blood-vessels. Dr. Belaieff describes in the capillary lym-
phatics of the penis, a lining of epithelial cells arranged in
a single layer. These.cells are oval, polygonal, fusiform or

. - 1 SAPPEY, op. tit., tome i., p. 621.

STRUCTURE OF THE LACTEAL AND LYMPHATIC VESSELS. 4:3 T

dentated, with 'their long diameter in the direction of the
axis of the vessels.1 The vessels themselves are completely
closed ; and the openings which were described by the older
anatomists were either accidental or imaginary.

In all but the capillary vessels, although the walls are ex-
cessively thin, three distinct coats can be distinguished. The
internal coat consists of a membrane lined with oblong
epithelial cells. These cells, however, do not form a con-
tinuous sheet, as in the capillaries. According to some anat-
omists, the membrane is composed of reticulated longitudi-
nal fibres ; but Sappey states that he has never been able to
distinguish any appearance of this kind.2 This coat is some-
what elastic, though it readily gives way when the vessels
are forcibly distended. The middle coat is composed of
longitudinal fibres of the white fibrous tissue, with delicate
elastic fibres and unstriped muscular fibres arranged trans-
versely. The external coat is composed of the same struc-
tures as the middle coat ; but the fibres are arranged, for the
most part, longitudinally. In this coat, the muscular fibres
do not form a continuous sheet, but are collected into sepa-
rate fasciculi, which have a direction either longitudinal or
oblique. The fibres of connective tissue are very abundant,
and loosely unite the vessels to the surrounding parts. The
internal and the middle coat are closely adherent to each
other ; but the external coat may readily be separated from
the others. Blood-vessels have been found in the walls of
the lymphatics, but as yet, the presence of nerves has not
been demonstrated.

The walls of the lymphatic vessels are very closely ad-
herent to the surrounding tissues ; so closely, indeed, that
even a small portion of a vessel is detached with great diffi-
culty, and the vessels, even those of large size, cannot be
followed out and isolated for any considerable distance.

1 Op. cit. — Journal de V Anatomic et de la Physiologic, Paris, 1866, tome ill,
p. 469.

2 Op. cit., tome i., p. 625.

438 ABSORPTION.

In all the lymphatic vessels, beginning a short distance
from their plexus of origin, are found numerous semilunar
valves, generally arranged in pairs, with their concavities
looking toward the larger trunks. These folds are formed
of -the two inner coats; but the fold formed of the lining
membrane is by far the wider, so that the free edges of the
valves are considerably thinner than that portion which is
attached directly to the vessel. In some of the vessels, at
the point where one lymphatic communicates with another,
there is a valve formed of two folds, one of which is much
wider than the other • but in the valves situated in the course
of the vessels, the curtains are of equal size. The valves are
very numerous in all of the lymphatics ; but they are most
abundant in the superficial vessels. Sappey counted from
sixty to eighty in the vessels of the arm, from the fingers
to the axillary glands, and from eighty to one hundred in
the long vessels of the lower extremities.1 The distance
between the valves is from one-twelfth to one-eighth of an
inch, near the origin of the vessels, and from one-quarter to
one-third of an inch, in their course. In the lymphatics situ-
ated between the muscles, the valves are less numerous.
They are always relatively few in the vessels of the head and
neck and in all that have a direction from above downward.
Though there are a number of valves in the thoracic duct,
they are not so numerous here as in the smaller vessels.

In their anatomy and general properties, the lymphatics
bear a close resemblance to the veins. Though much thinner
and more transparent, their coats have nearly the same ar-
rangement. The arrangement of valves is entirely the same ;
and in both systems, the folds prevent the reflux of fluids when
the vessels are subjected to pressure. A number of forces
(which will be considered hereafter) combine to produce the
flow of lymph and chyle in the absorbent system. Among
these is intermittent pressure from surrounding parts, which

1 Op. cit., tome i., p. 618.

LYMPHATIC GLANDS. 439

could only operate favorably in vessels provided with numer-
ous valves.

We have already referred to the great elasticity of the
lymphatics. It is now pretty generally admitted that* the
]arger vessels and those of medium size are also endowed
with contractility, though the action of their muscular
fibres, like that of all fibres of the involuntary or non-stri-
ated variety, is slow and gradual. Todd and Bowman have
demonstrated this property by mechanically irritating the
thoracic duct in an animal recently killed, but they observed
that the contraction was very slow.1 Milne-Edwards, quot-
ing from a manuscript presented by Colin to the Academy of
Sciences, in 1858, states that this observer noted alternate
filling and emptying of some of the lacteal vessels in the
mesentery of the ox ; portions of the vessels becoming alter-
nately enlarged in the form of pouches, and contracted so
that they almost disappeared.2 There can be no doubt that
the lymphatic vessels possess a certain degree of contractility
which is fully as marked, perhaps, as in the venous system.

Lymphatic Glands. — In the course of the lymphatic ves-
sels, are found numerous small lenticular bodies, called lym-
phatic glands. The number of these glands is very great,
though it is estimated with difficulty, from the fact that
many of them are very small and are consequently liable
to escape observation. It may be stated as an approxi-
mation that there are from six to seven hundred lymphatic
glands in the body. Their size and form is also very vari-
able within the limits of health. They are generally flat-
tened and lenticular, some as large as a bean, and others as
small as a small pea, or even a pin's head. They are ar-
ranged in two sets : one superficial, corresponding with the
superficial lymphatic vessels, and a deep set, corresponding

1 TODD AND BOWMAN, Physiological Anatomy and Physiology of Man, Phila-
delphia, 1857, p. 615.

' MILNE-EDWARDS, Lecons sur la Physiologic, Paris, 1859, tome iv., p. 511.

44:0 ABSORPTION.

with the deep vessels. The superficial glands are most nu-
merous in the folds at the flexures of the great joints, and
about the great vessels of the head and neck. The deep-seated
glands are most numerous around the vessels coming from
the great glandular viscera. A distinct set of large glands is
found connected with the lymphatic vessels between the
folds of the mesentry. These are known as the mesentric
glands. All of the lymphatic vessels pass through glands
before they arrive at the great lymphatic trunks, and most
of them pass through several glands in their course.

There is some difference of opinion among anatomists
concerning the intimate structure of the lymphatic glands.
Some regard them as composed simply of a plexus of lym-
phatic vessels, held together by a delicate stroma of fibrous
tissue ; while others deny that there is any direct communica-
tion between the afferent and the efferent vessels, assuming
that the vessels which penetrate the glands break up into
small branches which open into a parenchyma, which is
filled with closed follicles, and that the fluids are collect-
ed from the glands by a second set of capillaries connected
with the efferent lymphatics. According to the latter view,
the meseiiteric glands are little more than collections of fol-
licles like the solitary glands of the intestines, held together
by a delicate fibrous structure. This difference^ of opinion
seems to be due to the different methods which have been
employed in studying the structure of the glands. Taking,
for example, the results arrived at by two prominent investi-
gators, Sappey, wrho has studied these organs with great
success by injections, seems to have clearly demonstrated a
lymphatic plexus in their interior ; while Kolliker, whose in-
vestigations have been confined chiefly to examinations of
the organs in a recent state, has not been able to follow out
the lymphatic vessels, but has accurately described the con-
tents of the alveoli, or what are regarded by others as closed
follicles. In attempting to represent what has been actu-
ally demonstrated concerning the structure of these bodies,

LYMPHATIC GLANDS. 441

we shall first take up the appearances which are observed in
the fresh structures, and afterward those points which have
been demonstrated by minute injections.

The perfect healthy glands are of a grayish- white or red-
dish color, of about the consistence of the liver, presenting a
hilum where the larger blood-vessels enter and the efferent
vessels emerge, and covered, except at the hilum, with rather a
delicate membrane, composed of inelastic, with a few elastic
fibres. Their exterior is somewhat tuberculated, from the
projections of the follicles just beneath the investing mem-
brane. The interior of the glands is soft and pulpy. It pre-
sents a coarsely granular cortical substance, of a reddish- white
or gray color, which is from one-sixth to one-fourth of an inch
in thickness in the largest glands. The medullary portion,
which comes to the surface at the hilum, is lighter colored and
coarser than. the cortical substance. Throughout the gland
are found delicate fasciculi of fibrous tissue connected with
the investing membrane, which serve as a fibrous skeleton
for the gland, and divide its substance into little alveoli. The
structure is far more delicate in the cortical than in the me-
dullary portion. Leydig compares this tissue to that of a
sponge, and says that " the connective tissue of the cortical
region corresponds to a very fine sponge, and that of the
medullary region to a coarse sponge." 1

Within the alveoli, are irregularly oval, closed follicles,
about 2^0- of an inch in diameter,2 filled with a fluid and
with cells like those contained in the solitary glands of the
intestines and the patches of Peyer. These follicles do not
seem to occupy the medullary portion of the glands, which,
according to Kolliker, is composed chiefly of a net-work of
lymphatic capillaries, mixed with rather coarse bands of
fibrous tissue.3 The follicular structures in the lymphatic

1 LEYDIG, Traite d1 Histologie de VHomme et des Animaux, Paris, 1866, p.
457.

3 ROBIN, Dictlonnaire de Nysten, Paris, 1865, article Lymphatique.

3 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 507.

442 ABSOKPTION.

glands resemble the closed follicles in the mucous membrane
of the intestinal canal and the Malpighian bodies of the
spleen.

The elaborate researches of Sappey leave scarcely any
doubt as to the course and arrangement of the lymphatic
vessels in the interior of the lymphatic glands, though the
view advanced by him that these bodies consist mainly of
lymphatics with a little fibrous tissue cannot be sustained.
By pricking a perfectly healthy gland with the delicate point
of his apparatus for injecting the lymphatics, he has seen the
mercury successively fill the different capillary vessels, and
pass into the vasa efferentia.1 Sappey does not appear, how-
ever, to have caused the injection to pass from the afferent
to the efferent vessels, entirely through this plexus ; and while
the fact of the continuity of these vessels through a capillary
plexus is extremely probable, it has not, as yet, been posi-
tively proven.

As far as has been ascertained, the following is the course
of the lymphatic vessels through the glands : From two to
six vasa afferentia approach the gland, and when within
about a quarter of an inch of it, break up into numerous small
branches which penetrate its investing membrane. In the
substance of the gland, these vessels are distributed in the
capillary plexus just described, and emerge by the vasa effer-
entia, which are always larger than the afferent vessels, and
are from one to three in number. In attempting to pass
injections entirely through the glands, the fluid has fre-
quently been observed to pass into the small veins ; so that
some anatomists have assumed that there is connection in
the substance of the glands between the lymphatics and the
blood-vessels. It is altogether probable that the passage of
fluids into the veins under these circumstances is due to rup-
ture of the vessels ; and at all events, the direct connection
between them and the lymphatics has never been satisfac-
torily demonstrated.

J SAPPEY, Traite d'Anatomie Descriptive, Paris, 1853, tome i., p. 629.

LYMPHATIC GLANDS.

443

Fig. 7.

The lymphatic glands are supplied with blood by some-
times one, but generally several small arteries, which pen
etrate at the hilum. These vessels pass directly to the
medullary por-
tion, and there
break up into
several coarse
branches, to be
distributed to
the cortical sub-
stance, where
they ramify in
an exceedingly
delicate capil-
lary net-work,
with rather
wide meshes,
in the closed
follicles found
in this portion
of the gland.
This capillary
plexus also re-
ceives branches Different varieties of lymphatic glands. (SAPPEY, Traite
„ <V Anatomic Descriptive, Paris, 1853, tome i., p. 632.)

from small ar-
terial twigs which penetrate the capsule of the gland at dif-
ferent points. Returning on themselves in the form of loops,
the vessels unite to form one or more large veins, which gen-
erally emerge at the hilum.

Very little is known regarding the distribution of the
nerves in the lymphatic glands. A few filaments from the
sympathetic system enter with the arteries, but they have
never been traced to their final distribution. The entrance
of filaments from the cerebro-spinal system has never been
demonstrated.

It is evident from the structure of the lymphatic glands.

ABSOEPTION.

that they must materially retard the passage of the lymph
toward the great trunks ; and it is well known in pathology
that morbid matters taken up by the absorbents are fre-
quently arrested and retained in the nearest glands.

The function of the lymphatic glands is very obscure.
By some they are supposed to have an important office in
the elaboration of the corpuscular elements of the lymph
and chyle ; and it has been observed that the lymph con-
tained in vessels which have passed through no glands is
relatively poor in corpuscles, while the large trunks and the
efferent vessels contain them in large numbers.1 This sin-
gle fact is indefinite enough, as regards the mode of forma-
tion of the lymph-corpuscles, but it represents about all
that is actually known concerning the function of the lym-
phatic glands. The mode of development of the leucocytes
in this situation will be more fully considered in connection
with the lymph and chyle.

In endeavoring to estimate the share which the lacteals
and lymphatics have in the function of absorption, it becomes
an important question to determine what principles these
vessels are capable of taking up, beside the fatty elements of
the food ; and how far, if at all, they assist the blood-ves-
sels in the absorption of the general products of digestion.
It is unnecessary again to recur to the function of the lac-
teals in the absorption of emulsified fats, for this has already
been discussed at sufficient length.3

Absorption of Albuminoids ~by the Lacteals. — Comparative
analyses of the lymph and chyle always show in the latter
fluid an excess of albumen and fibrin. As we may reason-
ably suppose that during the intervals of digestion the lac-
teals carry ordinary lymph, for at this time these vessels are
filled with a colorless transparent fluid, having the general
physical characters of lymph, it is natural to infer that the

1 KULLIKER, Manual of Human Microscopic Anatomy, London, I860, p. 513.

2 See page 426.

ABSORPTION OF ALBUMINOIDS BY THE LACTEALS. 445

excess of albumen and fibrin in the white chyle is due to
absorption of albuminoids from the intestinal canal. A
number of years ago, experiments were made upon this sub-
ject by Prout and Marcet, in which the chyle was collected
from the thoracic duct in dogs fed upon different substances.
These observers noted marked differences in the composition
of the chyle in the animals fed exclusively upon vegetable, and
those fed upon animal food ; in the latter case, the propor-
tion of albumen being very much greater.1 The fact that
the fluids were taken from the thoracic duct, where the chyle
from the intestine is mixed with all the lymph from the lower
extremities and the pelvic organs, takes away somewhat from
the value of the experiment. This is all the more evident,
as in the more recent experiments of Bouchardat and San-
dras, it was found that the chyle from the thoracic duct
had about the same composition in animals fed with gum,
starch, sugar, fibrin, albumen, or gelatine.2 Bouchardat and
Sandras conclude, from these observations, that the lacteals
absorb only fats. But the observations of Lane and Bees
upon this point, in which the chyle was taken from the lac-
teals before they emptied into the thoracic duct, are more
satisfactory. IVIr. Lane collected the chyle from the lacteals
of a donkey, seven and a half hours after a full meal of oats
and beans, and compared its composition with that of the
lymph. The analyses were made by Dr. Bees, who found
that the chyle contained about three times as much albumen
and fibrin as the lymph.3 While by far the greater part of
the products of digestion of the albuminoids is absorbed by

1 PROUT, Phenomena of Sanguification, and on the Blood in general. — Annals
of Philosophy, London, 1819, vol. xiii., p. 25 ; and MARCET, Some Experiments on
the Chemical Nature of Chyle. — Medico- Chirurgical Transactions, London, 1819,
vol. vi., p. 618.

2 BOUCHARDAT ET SANDRAS, Rechtrches sur la Digestion. — Annuaire de Tlw-
rapeutique, Paris, 1845, p. 259.

3 LANE, Lymphatic and Lacteal System. — Cyclopaedia of Anatomy and Physi-
ology, London, 1839-1 84 7, vol. iii., p. 223. These analyses were also published
by Rees in the London Medical Gazette, January 1, 1841, vol. xxvii., p. 547.

446 ABSORPTION.

the blood-vessels, there can be no doubt that a small portion
is also taken up by the lacteals.

Absorption of Glucose and Salts ~by the Lacteals. — What
has just been stated regarding the absorption of albuminoids
applies with equal force to saccharine matters and the in-
organic salts. Small quantities of sugar and sometimes lac-
tic acid have been detected in the chyle from the thoracic
duct in the herbivora ; * and the presence of sugar in both the
lymph and the chyle has been accurately determined by
Colin.2

It is true that the products of the digestion of saccha-
rine and amylaceous matters are taken up mainly by the
blood-vessels, but a small quantity is also absorbed by the lac-
teals. In the comparative analyses of the chyle and lymph
by Dr. Rees, the proportion of inorganic salts was found to
be considerably greater in the chyle.3 The great excess in
the quantity of blood coming from the intestine and the
rapidity of its circulation, as compared with the chyle, will
explain the more rapid penetration by endosmosis of the
soluble products of digestion.

Absorption of Water ~by the Lacteals. — There can be no
doubt that a small portion of the liquids taken as drink
finds its way into the circulation by the lacteals, though the
greatest part passes directly into the blood-vessels. This has
been proven by experiments of a most positive character.
Leuret and Lassaigne state that when an animal is fed with
an aliment which is very substantial, and is killed during
digestion, the thoracic duct contains a very small quantity
of chyle ; but when the animal has taken liquids with the
food, the thoracic duct and the lacteals are very much dis-

1 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 35Y.

2 COLIN, De T Origine du Sucre contenu dans le Chyle. — Journal de la Phy-
siologic, Paris, 1858, tome i., p. 539 et seq.

3 Loc. cit.

ABSORPTION OF WATER BY THE LACTEALS. 447

tended.1 In an experiment by Ernest Burdach, a dog was
deprived of food and drink for twenty-four hours, after which
he was allowed to drink water, and, in addition, half a pound
was injected into the stomach. The animal was killed a
half an hour after, and the thoracic duct was found engorged
with watery lymph, which contained a very small number of
lymph-corpuscles.2

In discussing the question of absorption by the blood-
vessels of the intestinal canal, we alluded to experiments
which showed that various poisonous substances introduced
into the intestines produced their characteristic effects upon
the system with great rapidity when the veins leading from
the part were intact, while no such effects followed when the
only avenue to the general system was through the lacteals.
During the time w^hen the question of exclusive absorption by
either the lacteals or the veins wTas so much agitated, a num-
ber of experiments were made by different physiologists to
show, on the one hand, that certain coloring matters and salts
were absorbed by the lacteals alone, and, on the other, that
these were absorbed only by the veins. These experiments have
lost much of their interest, now that the question of venous
absorption is definitively settled. "Without again discussing
these observations in detail, it may be stated as the general
results of experiments on this subject, that few, if any, of the
active poisons were found to be absorbed from the alimentary
canal, except by blood-vessels ; and when soluble coloring
matters, or salts which could be easily recognized, were
found in the lacteals or the thoracic duct, after they had been
introduced into the intestine, they penetrated in small quan-
tity and very slowly ; while it has been repeatedly found that
the same substances were taken up by the veins with great
rapidity and excreted, in many instances, by the urine.

1 LEURET ET LASSAIGNE, Eecherches Physiologiques et Chimiques pour servir
d FHistoire de la Digestion, Paris, 1825, p. 197.

2 G. F. BURDACH, TraitS de Physiologic, Paris, 1841, tome ix., p. 253 : addi-
tion by Ernest Burdach.

44:8 ABSORPTION.

The earlier physiologists, who supposed that all the pro-
ducts of digestion entered the system by the thoracic duct,
attached a great deal of importance to experiments showing
the effects of shutting off the chyle from the vascular system,
by tying or destroying this great canal. A number of very
interesting cases of obliteration of the thoracic duct in the
human subject has also been reported by Astley Cooper,
Andral, and others. ' In three cases observed by Cooper, the
duct was found completely obstructed ; and in two, he was
able to follow out anastomosing lymphatic branches, which
carried the chyle past the obstacle, so that its passage to the
venous system was not interrupted. In the remaining case,
the obstruction was accidentally discovered in a subject that
had been so far dissected as to render it impossible to ascertain
whether or not any anastomosing vessels existed.1 In^a case
of obliteration of the thoracic duct, reported by Andral, the
canal had become an impervious cord for a considerable por-
tion of its extent, but there was a large vessel, like a seconc^
thoracic duct, which extended from below the obstruction,
opening into the duct a considerable distance above, so that
the flow of chyle was not in the least interrupted.3

In nearly all the experiments which have been performed
upon the lower animals, ligation of the thoracic duct has
been followed by death, except where large communicating
vessels were found to exist, which would allow of the pas-
sage of the chyle into some part of the venous system.
Lower tied the duct in dogs, and the animals survived but a
few days.3 In the experiments of Cooper, three dogs, out of
four which were operated upon, died from rupture of the

1 ASTLEY COOPER, Three Instances of Obstruction of the Thoracic Duct, with
some Experiments showing the Effects of tying that Vessel. — Medical Records and
Researches selected from the Papers of a Private Medical Association, London,
1798, p. 86 et seq.

2 ANDRAL, FILS, Recherches pour servir' d VHistoire des Maladies du Systeme
Lymphatique. — Archives Generates de Medecine, Paris, 1824, tome vi., p. 505.

3 LOWER, Tractatus de Corde, item de Motu et Colore Sanguinis, ct Chyli
in cum Transitu. — Amstelodami, 1(569, p. 220 et seq.

ABSOKPTTON OF WATER BY THE LACTEALS. 449

receptaculum chyli, and in the fourth, which was afterward
killed, a vessel was fonnd extending from the duct below the
point of ligature to the great lymphatic vein on the right side.1
The experiments of Dupuytren upon horses were followed
by nearly the same results. Some of the animals died after
five or six days, and others apparently recovered. In those
that fried, it was found impossible after death to pass an in-
jection from the lower part of the duct, below the ligature,
into the subclavian vein ; but in the animals that survived, it
was always easy to pass any kind of liquid from the duct into
the vein, by numerous communicating vessels located in the
posterior and^he anterior mediastinum. Magendie, who was
present at the dissection of a horse upon which Dupuytren
had tied the duct six weeks before, found evident communica-
tions between that portion of the duct situated below the point
of ligature and both subclavian veins, although the duct itself
had been completely obliterated.8 The experiments of Flan-
drin seem to indicate that ligation of the thoracic duct is not
necessarily fatal, even though the flow of chyle be com-
pletely arrested. In one experiment upon a horse that was
old and feeble, death took place in three days, while in
eleven other experiments, the animals survived, and were
killed generally fifteen days after ligation of the duct ; but
no attempt was made to determine the existence or non-exist-
ence of anastomosing branches communicating with the veins
in*the neck.3 '

The early experiments of Du Yerney 4 and others, which

1 Loc. cit., p. 104 et seq. In one of these experiments the duct was simply
divided in the neck and was not tied. The animal died on the fifth day.

2 MAGENDIE, Memoire sur les Organes de V Absorption chez les Mammiferes.
— Journal de Physiologic, Paris, 1821, tome i., p. 21.

3 FLANDRIN, Suite des Experiences sur V Absorption des Vaisseaux Lympha-
tiques dans les Animaux. — Journal de Medecine, Chirurgie, Pharmacie, etc., Paris,
1791, tome Ixxxvii., p. 226 et seq.

4 Histoire de 1} Academic des Sciences de Paris, 1675, tome i., p. 197. Cu
Verney did not tie the thoracic duct, but applied a ligature to "the subclavian
vein above the thoracic canal, and the jugular above its insertion."

29

450 ABSOKPTION.

it is unnecessary to quote in detail, indicate that death must
take place after ligation of the thoracic duct, unless there
exist some communicating vessel by which the chyle can be
discharged into the venous system. We cannot assume, with
Lower, that a dog can die of starvation within three days "af-
ter this operation ; but it is an inevitable conclusion, from
the experiments cited above, that the cause of death is
chiefly mechanical, and is due to distension, and sometimes
rupture, of some of the vessels. Cooper found that the recep-
taculum chyli was ruptured in dogs when the extremity of
the duct was exposed soon after eating and simply com-
pressed for a few minutes with the fingers.1 - A permanent
loss of the nutritive material which passes up the thoracic
duct might produce death from inanition; but usually the
fatal result follows too soon to admit of this explanation.
Leuret and Lassaigne tied the thoracic duct in a dog, which
was treated antiphlogistically after the operation, by M.
Watrin, and restored in fifty-eight days in good condition.
This animal was afterward killed during digestion, and the
abdomen opened. It was ascertained that the duct was sin-
gle, and the receptaculum and the lacteals contained a small
quantity of chyle.2 Leuret and Lassaigne reasoned, from
this single experiment, that there exists a communication
between the lacteals and the radicles of the portal vein.
They did not, however, demonstrate by injection that there
existed no communication between the lower portion of the
duct and the veins of the neck.

Absorption from Parts not connected with the Digestive
System'.— Aside from the entrance of gases into the blood
from the pulmonary surface, physiological absorption is al-
most entirely confined to the mucous membrane of the ali-
mentary canal. It is true that liquids may find their way

1 ASTLEY COOPER, op. a/., p. 110.

2 LEURET ET LASSAIGNE, Rccherches Physiologiques et Chimiques pour servir
d VHistoire de la Digestion, Paris, 1825, p. 180 et seq.

ABSOKPTTON FEOM THE SKIN". 451

into the circulation through the skin, the lining membrane
of the air-passages, the reservoirs, dncts, and parenchyma of
glands, the serous and other closed cavities, the areolar tis-
sues, the conjunctiva, the muscular tissue, and, in fact, all
parts which are supplied with blood-vessels; but here the
absorption of foreign matters is an occasional or an acci-
dental circumstance, and is not connected with the general
process of nutrition. It is now well known that all parts
of the body, except the epidermis and its appendages, the
epithelium, and some other structures which are regularly
desquamated, are constantly undergoing change, and the
effete matters which result from their decay are taken up
by what is called interstitial absorption, and carried by the
blood to the proper organs, to be excreted. It would seem
probable that the vessels of these parts would also be capable
of taking up soluble foreign substances when presented to
them ; and this is, indeed, the fact with regard to all parts in
which the nutritive processes are even moderately active, or
where the structures covering the vascular parts are per-
meable.

Absorption from the Skin. — It is now generally admitted
that absorption can take place from the general surface,
though at one time this was a question much discussed by
physiologists and practical physicians. The proofs, however,
of the entrance of certain medicinal preparations from the
surface of the body are now entirely conclusive ; and the con-
stitutional effects of medicines administered in this way are
frequently as marked as when they are taken into the ali-
mentary canal. But the question which is of most interest
to us as physiologists concerns the normal functions of the
skin as an absorbing surface.

Looking at this subject purely from a physiological point
of view, absorption from the skin, under ordinary conditions,
must be exceedingly slight, if, indeed, it take place at all.
There are a few observations by the older physiologists

452 ABSOKPTKXN".

which would at first seem to show that a certain amount of
water is taken up by the skin when the atmosphere is un-
usually moist. In all of these, however, the conclusion is
drawn from the circumstance that the weight is occasionally
somewhat increased under these conditions ; but no account
is taken of the fact, that when the surrounding atmosphere
is moist, the amount of the exhalations is greatly decreased.
The lungs, also, present an immense absorbing surface,
which is not at all considered. Experiments on this point
are not sufficiently definite to warrant any positive conclu-
sions ; but it is evident that if any thing enters in this way,
the quantity must be excessively minute.

The experiments upon the entrance of water and soluble
substances through the skin, when the body has been im-
mersed for a long time in a bath, are somewhat contradictory.
Most experimenters have noted an increase in the weight,
which they attribute to absorption of water, but others pro-
fess to have observed a slight diminution in the weight
of the body.

In some experiments on this subject, by Madden, in which
all necessary precautions were adopted, the air being respired
through a tube passed out of the window of the room, so that
no unusual absorption of moisture could take place by the
lungs, the results were very conclusive.1 In experiments of
this kind there are many modifying influences to be guarded
against. For example, it has been found to be important to
regulate carefully the temperature of the bath ; for when it
exceeds that of the body, there may be a loss of weight by
cutaneous transpiration. It is stated by Longet 2 that when
the temperature of the water is lower than that of the body,
there is a gain in weight ; but that the cutaneous exhalation

1 MADDEN, An Experimental Inquiry into the Physiology of Cutaneous Ab-
sorption, etc., Edinburgh, 1838, p. 59 et seq.

2 LONGET, TraiU de Physiologie, Paris, 1861, tome i., p. 296. In the work
of Longet will be found a very full account of the various experiments in favor
of, and opposed to, cutaneous absorption.

ABSORPTION FROM THE SKIN. 453

and absorption are balanced when the temperature of the
bath and the body are the same. There is another source
of complication in these observations, which has been
brought forward very strongly by a recent French writer, M.
Delore. This observer has carefully noted the increase in
weight of the hair, nails, and epidermis, after immersion for
half an hour in distilled water, and has always found it to Jbe
very considerable. He assumes that this is more than suffi-
cient to account for the increase in the weight of the en-
tire body after immersion in water for half an hour, which
amounts to about seven hundred grains.1

There are, nevertheless, facts which render it certain that
water can be absorbed by the skin. In an elaborate series of ex-
periments by Collard de Martigny, it was proven conclusively
that water could be absorbed in small quantity by the skin of
the palm of the hand. In one experiment, a small bell-glass
filled with water was applied hermetically to the palm. This
was connected with a tube bent in the form of a siphon, also
filled with water, the long branch of which was placed in a
vessel of mercury. After the apparatus had been applied
for an hour and three-quarters, the mercury was found sen-
sibly elevated in the tube, showing that a certain quantity
of the water had disappeared.2 Recently a very extended
series of observations upon the absorption of water and solu-
ble substances has been made by Dr. "Willemin, in which it
is conclusively proven that water is absorbed in a bath, and
that various medicinal substances may be taken up by
the skin in this way, and can be detected afterward in the
urine. In a large number of experiments, he found that the
weight of the body, after remaining in a tepid bath for from
thirty to forty-five minutes, was generally stationary ; but

1 DELORE, De I1 Absorption des Medicaments par la Peau saine. — Journal de la
Physiologic, Paris, 1863, tome vi., p. 274.

2 COLLARD DE MARTIGNY, Observations et Experiences sur F Absorption Cu-
tanee de VEau, du Lait, et du Bouillon. — Archives Generates de Medecine, Paris,
1821, tome xi., p. 83.

454: , ABSORPTION.

that sometimes there was a very slight diminution in weight
and sometimes a very slight increase. By comparative ob-
servations, however, he found that the diminution of weight
in the bath was always less than the amount lost by the
same subject in the air. Dr. "Willemin employed a very
delicate apparatus for weighing, and his observations were
apparently conducted with great care. He also confirmed
the statement of "W. F. Edwards and others, that transpiration
from the general surface goes on in a bath. This he showed
by differences in the composition of the bath before and
after immersion of the body. These observations do much
to reconcile the contradictory experiments of others, in some
of which a diminution in weight was observed, while in
some an increase was noted.1 In studying this subject, it
must always be remembered that there is a constant loss
of weight by evaporation from the general surface and from
the lungs ; a fact which was not taken into account by some
of the earlier experimenters.

It has been frequently remarked that the sensation of
thirst is always least pressing in a moist atmosphere, and
that it may be appeased to a certain extent by baths. It is
true that, in a moist atmosphere, the cutaneous exhalations
are diminished, and this might account for the maintenance
of the normal proportion of fluids in the body with a less
amount of drink than ordinary; but we could hardly ac-
count for an actual alleviation of thirst by immersion of the
body in water, unless we assumed that a certain quantity of
water had been absorbed. A striking example of relief of
thirst in this way is given by Captain Kennedy, in the narra-
tive of his sufferings after shipwreck, when he and his men

1 WILLEMIN, Recherches Experimentales sur V Absorption par le Tegument
externe de VEau ft des Substances solubles. — Archives Generales de Medecine,
Paris, 1863, 6me serie, tome ii., pp. 5, 177, 313 ; and Nouvelles Recherches sur
V Absorption Cutanee, Id., 1864, tome iii., p. 513. In the first article, Dr. Wil-
lemin gives an admirable historical review of the experiments on cutaneous
absorption. The last article contains a great number of original observations,
and the conclusions.

ABSOEPTION FKOM THE EESPIKATOEY SURFACE. 455

were exposed for a long time without water in an open boat.
With regard to his sufferings from thirst, he says : " I cannot
conclude without making mention of the great advantage I
derived from soaking my clothes twice a day in salt water,

and putting them on without wringing There is

one very remarkable circumstance, and worthy of notice,
which was, that we daily made the same quantity of urine as
if we had drunk moderately of any liquid, which must be
owing to a body of water absorbed through the pores of the
skin. ... So very great advantage did we derive from
this practice, that the violent drought went off, the parched
tongue was cured in a few minutes after bathing and washing
our clothes ; at the same time we found ourselves as much
refreshed as if we had received some actual nourishment." *

The mechanism of the introduction of various salts in
solution in water and of certain medicinal substances through
the skin belongs chiefly to therapeutics. There can be no
doubt of the penetration of numerous articles simply placed
in contact with the surface ; and it is well known that the
skin denuded of its epidermis absorbs soluble substances
with great rapidity. Though observations on the absorption
of salts in medicated baths are somewhat contradictory, there
are enough positive experiments on this point to leave no
doubt as to the actual penetration of these principles, which
are to be recognized, indeed, in the urine. The penetration
of most medicinal substances by the skin is very much facili-
tated by frictions, employing what is known in therapeutics
as the iatroleptic method.2

Absorption from the Respiratory Surface. — In studying
the physiological anatomy of the respiratory apparatus, we

1 Narrative of Captain Kennedy's losing his vessel at sea, and his distresses
afterward, communicated to his owner. — Annual Register, London, 1769, p. 190.

2 For a full account of the absorption of medicinal substances by the healthy
skin, the reader is referred to the article by Delore, in the Journal de la Physiolo-
gie, Paris, 1863, tome vi., p. 249 et seq.

456 AESOEPTION.

have seen how admirably the respiratory surface is calculated
for the introduction of gaseous principles into the blood.1
The great rapidity with which the oxygen of the inspired
air penetrates through the delicate covering of the pulmo-
nary vessels has already been fully considered under the head
of Respiration. Under natural conditions, the gases of the
air are the only principles absorbed by the lungs ; but exam-
ples of the absorption of other gaseous matters are exceed-
ingly common, and this process has been the subject of nu-
merous experiments by physiologists. The fact of the ab-
sorption of foreign substances by the lungs, also, has long
been definitely settled ; but this belongs to pathology or to
therapeutics, rather than to physiology.

It is now almost universally conceded that animal and
vegetable emanations may be taken into the blood by the
lungs and produce certain well-marked pathological condi-
tions. It is supposed that many contagious diseases are prop-
agated in this way, as well as some fevers and other gener-
al diseases which are not contagious. With regard to certain
poisonous gases and volatile principles, the effects of their
absorption by the lungs are even more striking. Carbonic
oxide and arseniuretted hydrogen produce death almost in-
stantly, even when inhaled in small quantity. The vapor of
pure hydrocyanic acid acts frequently with great promptness
through the lungs. Turpentine, iodine, and many medicinal
substances may be introduced with great rapidity by inhala-
tion of their vapors ; and we well know the serious effects
produced by the emanations from lead or mercury in persons
who work in these articles. Among the most striking proofs
of the absorption of vapors by the lungs are the effects
of the inhalation of chloroform and ether. These pass into
the blood and manifest their characteristic ansesthetic influ-
ences almost immediately. 'Not only have vapors introduced
in this way been recognized in the blood, but many of the
principles thus absorbed are excreted by the kidneys, and

1 See vol. i., Respiration.

ETC. 457

may be recognized by their characteristic reactions in the
urine.

As would naturally be expected, water and substances in
solution, when injected into the respiratory passages, are rapid-
ly absorbed ; and poisons administered in this way manifest
their peculiar effects with great promptness.1 Experimenters
on this subject have shown the facility with which liquids
may be absorbed from the lungs and the air-passages, but it
must be remembered that the natural conditions are never
such as to admit of this action. The normal function of the
lungs is to absorb oxygen, and sometimes a little nitrogen
from the air ; and the absorption of any thing else by these
surfaces is unnatural, and generally deleterious.

Absorption from Closed Cavities, Reservoirs of Glands,
etc. — Facts in pathology showing absorption from closed
cavities, the areolar tissue, the muscular and nervous tissue,
the conjunctiva, and other parts, are sufficiently numerous.
In all cases of effusion of serum into the pleural, peritoneal,
pericardial, or synovial cavities, in which recovery takes
place, the liquid becomes absorbed. It has been shown by
experiment that warm water injected into these cavities is
disposed of in the same way. In 1683, Dr. "William Mus-
grave injected water into the thorax of a greyhound, produ-
cing at first considerable disturbance, but in a few days the
fluid was removed by absorption, and entire recovery took
place. On one occasion, a pound and a half of water was
injected into one side of the chest and half a pound into the
other.2 Experiments of this nature have been frequently

1 Numerous experiments, which it is not necessary to discuss in detail, have
been performed, showing the prompt absorption of poisons from the respiratory
surfaces. Magendie repeatedly showed this with solutions of nux vomica and
other poisons, in his public demonstrations (Phenomenes Physiques de la Vie,
Paris, 1842, tome i., p. 31). It has been found by Magendie and others that this
is one of the most rapid ways in which poisons in solution can be introduced into
the system.

2 MUSGRAVE, Warm Water injected into the Tliorax of a Bitch. — Philosophical

458 ABSORPTION.

repeated, with the same results. Effusions into the areolar
tissue are generally removed by absorption. In cases of
penetration of air into the pleura or the general areolar tis-
sue, absorption likewise takes place ; showing that gases may
be taken up in this wray as well as liquids. Effusions of
blood beneath the skin or the conjunctiva, or in the muscular
or nervous tissue, may become entirely or in part absorbed.
It is true that these are pathological conditions, but in the
closed cavities, the processes of exhalation and absorption are
constantly going on, though not very actively.

Experiments are not wanting to confirm these facts. It
is very common to produce dilatation of the pupil by the
application of a solution of atropine to the conjunctiva. Ma-
gendie made numerous experiments upon the relative rapid-
ity of absorption of poisons from the areolar tissue, the pleu-
ra, and some of the other serous cavities.1 These, however,
only confirmed what has been so often observed in pathology
and therapeutics. As regards absorption from the areolar
tissue, the administration of remedies by the hypodermic
method, which is now so common, is a daily proof of the
facility with which soluble principles are taken into the blood
when introduced beneath the skin.

Under some circumstances, absorption takes place from
the reservoirs of the various glands, the watery portions of
the secretions being generally taken up, leaving the solid
and the organic matters. It is supposed that the bile becomes
somewhat inspissated when it has remained for a time in the
gall-bladder, even when the natural flow of the secretion is
not interrupted. Certainly, when the duct is in any way
obstructed, absorption of a portion of the bile takes place,
as is proven by coloration of the conjunctiva, and even of
the general surface. The serum of the blood, under these
conditions, will always be found strongly colored with bile.

Transactions, No. 240, p. 181 ; reprinted in the Abridgment, London, 1749,
fifth edition, vol. iii., p. 78.

1 MAGENDIE, Phenomenes Physiques de la Vie, Paris, 1842, tome i., p. 29 ctseq.

ABSORPTION OF FATS AND ESTSOLTJBLE SUBSTANCES. 459

It is probable that some of the watery portions of the
urine are reabsorbed by the mucous membrane of the urinary
bladder, when the urine has been long confined in its cavity ;
though this resorption is ordinarily very slight. A great
many cases of discharge of urinary matters by the stomach
and intestines, skin, etc., when the urine has been long re-
tained, have been reported by the older physiologists, and
were supposed to indicate resorption of these principles from
the bladder. The mechanism of the excretion of urinary
matters was not understood before the experiment^ of Pro-
vost and Dumas, who showed that urea will accumulate in
the blood after the extirpation of both kidneys in the inferior
animals.1 It is now generally admitted that this takes place
when the function of excretion of urine is seriously inter-
fered with, and that an attempt is made by Nature to re-
move these effete principles from the system by the stomach,
intestine, skin, and lungs. It is possible, therefore, that the
vicarious discharge of urinary matters in the cases reported,
before the true process of excretion by the kidneys was un-
derstood, was due to accumulation of the constituents of the
urine in the blood, and not their resorption from the urinary
passages.

Absorption may take place from the ducts and the par-
enchyma of glands, though this occurs chiefly when foreign
substances have been injected into these parts.

Absorption of Fats and Insoluble Substances.

The general proposition that all substances capable of
being absorbed are soluble in water or in the digestive fluids
must be modified in the case of the fats. These are never
dissolved in any appreciable quantity in digestion, the only
change which they undergo being a minute subdivision in
the form of a very fine emulsion. In this condition, the fats

1 PROVOST ET DUMAS, Examen du Sang et de son Action dans les divers
PMnomenes de la Vie. — Annales de Chimie et de Physique, Paris, 1823, tome
xxiii., p. 90.

460 ABSORPTION.

are taken up by the lacteals, and may be absorbed in small
quantity by the blood-vessels. Though it is now pretty well
understood how endosmotic liquids pass through the walls
of the blood-vessels and absorbents, the mechanism of the
penetration of fatty particles, which is no less constant, is
still somewhat obscure. We cannot at the present day in-
voke the aid of orifices in the vessels in explanation of this phe-
nomenon ; for the opinion of the best anatomists is decidedly
against the existence of these orifices in the lacteal capillaries,
though some still adhere to the view that they really exist,
and it is certain that there are no such openings in the capil-
lary blood-vessels.1

There can be no question with regard to the actual pene-
tration of the minute particles of the chyle into thelacteals,
and even into the blood-vessels. In birds, indeed, all the fat
which is absorbed is taken up by the blood-vessels, the lym-
phatics .of the intestine never containing a milky fluid.2
Assuming, then, that the walls of these vessels have no
orifices through which the fatty particles can pass, it is

• 1 It is chiefly with reference to the penetration of fatty particles that the
question of the existence or non-existence of orifices in the smallest lacteals is
interesting. Cruikshank, who wrote an elaborate memoir on the anatomy of
the absorbent system, in the latter part of the last century, not only .admits
the existence of these openings, but actually estimates their number in each
villus. He examined the villi in the intestines of a woman who had died sud-
denly, and in whom the lacteal system was filled with coagulated chyle. He and
Dr. William Hunter examined the villi with the microscope, estimating about
fifteen or twenty openings on each villus, in the jejunum. — (CRUIKSHANK, The
Anatomy of the Absorbing Vessels of the Human Body, second edition, London,
1790, p. 59). Kb'lliker (Manual of Human Microscopic Anatomy, London, 1860,
p. 329) describes striae in the cell-wall, which he remarks may possibly be at-
tributed to extremely fine canals. Beaunis (Journal de la Physiologic, Paris,
1863, tome vi., p. 339) quotes and confirms the observations of Kecklinghausen
(VIRCHOW'S Archiv, Berlin, 1862, Bd. xxvi., S. 188), who professes to have
demonstrated openings in the lacteals by filling them with a solution of nitrate of
silver, when the openings presented the appearance of black points. In none of
these observations, is the evidence sufficiently conclusive to warrant the assump-
tion of the existence of openings in any part of the absorbent system.
2 BERNARD, Lecons de Physiologie Experimental, Paris, 1856, p. 317.

ABSORPTION OF FATS AND INSOLUBLE SUBSTANCES. 461

evident that under certain circumstances, fatty emulsions
must be endosmotic, or, in other words, they are capable
of passing through membranes.

It is true that the currents which take place between two
miscible liquids of different densities separated by an animal
membrane do not usually occur when one of these liquids is
a fatty emulsion ; and this is explained by the general law that
all substances, in order to pass through membranes, must be
in solution. It must be remembered, however, that we can
but roughly imitate the physiological conditions of any func-
tion, in experiments out of the organism. In an endos-
mometer, we usually have two liquids of different densities
separated by the membrane, and the currents are dependent
upon very simple physical laws. In the organism, the blood
is moving with great rapidity in vessels possessing contrac-
tile and elastic coats ; the diameter of the vessels is subject
to great variations ; the liquids which enjer the blood-vessels
or the lacteals pass through epithelial cells and other struc-
tures which are in a condition of continual metamorphosis ;
the walls of the vessels are thinner than any membrane which
we can make use of ; and there is a host of conditions which
cannot be fulfilled in any apparatus that can be artificially
constructed. We may roughly imitate the movement of the
circulating fluids, and then it is found that the activity of
the endosmotic current is greatly increased.

It has been found, also, that the chemical reaction of
the endosmotic liquids has an important influence upon
osmotic currents. This latter condition is most interesting
with regard to the absorption of fats. While it has been
found invariably that neutral emulsions will not pass through
membranes and mix with pure water or with neutral fluids,
it has been conclusively demonstrated by Matteucci that the
passage of fats readily takes place when both of the solutions
are alkaline. This observer, having made an emulsion of
olive-oil with water containing 4*3 parts per thousand of
potash, introduced into it an endosmometer likewise filled with

462 ABSOEPTION.

a feebly alkaline fluid. The membrane used was the urinary
bladder of the ox, and the temperature was 80° Fahr. at the
beginning of the experiment. In a very short time, the
liquid had mounted in the endosmometer more than an inch.1
In these experiments, the liquids were not more strongly al-
kaline than the blood or the lymph ; and it is fair to infer
that in the intestine, where the conditions are as favorable
for absorption as possible, the minute fatty pajticles of the
chyle can pass through the coats of the lacteals or the .blood-
vessels to the lymph and the blood, which fluids are always
distinctly alkaline. Though we cannot at present explain
precisely how emulsions pass through membranes in which
no orifices can be demonstrated, the fact of their penetration
can hardly be doubted.

In studying the mechanism of the penetration of fatty
particles into the intestinal villi, it has been ascertained that
the epithelial cells covering the villi play an important part
in this process. It was first ascertained by Goodsir that
during the digestion of fat these cells became filled with fatty
granules.2 This fact has been confirmed by Gruby and
Delafond,3 Kolliker,4 and others. Prof. Dalton, in his work
on physiology, figures the appearances of the intestinal

1 MATTEUCCI, Lecons sur les Phenomenes Physiques des Corps Vivants, Paris,
1847, p. 105.

2 GOODSIR, On the Structure of the Intestinal Villi in Han and certain of the
Mammalia, with some Observations on Digestion, and the Absorption of Chyle.
— The Edinburgh New PhilosophicalJournal, 1842, vol. xxxiii., p. 167. Goodsir
thought that the epithelium of the villi was for the protection of these parts
during the intervals of digestion, and that the cells were always desquamated dur-
ing absorption ; but this view is not now entertained.

3 GRUBY ET DELAFOND, Resultats des Recherches faites sur V Anatomic et les
Fonctions des Villosites Intestinales, V Absorption, la Preparation et la Composition
organique du Chyle dans les Animauz. — Comptes Rendus, Paris, 1843, tome xvi.,
p. 1194. These authors pointed out the differences between the epithelial cells
during fasting and during digestion ; but they made several errors in their ob-
servations, and described openings and ciliae on the free ends of the epithelium.

4 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p.
329.

ABSOKPTION OF FATS AND INSOLUBLE SUBSTANCES. 463

epithelium during the digestion of fat, contrasted with the
epithelium observed during the intervals of digestion ; showing
the cells, during absorption, filled with fatty granules.1 The
hypothesis of Briicke, that the free ends of these cells have
no membrane, and that the fat enters to be passed out at
openings in the pointed ends, cannot be sustained ; for Kolli-
ker has demonstrated that the entire layer of epithelium
covering the villi is itself covered by a continuous mem-
brane.2

A more accurate knowledge of cell-action might enable
us to explain the mechanism of the passage of fat through
these structures in the intestine. In the general process of
nutrition, fatty granules are frequently deposited in various
tissues, cells, etc., by virtue of an inherent property common
to all living tissues, which enables them to select, as it were,
certain principles from the nutritive fluid. It is as difficult
to explain how fatty particles pass out through the walls of the
capillary blood-vessels and penetrate cells and other structures,
as it is to understand how the particles of chyle penetrate
the cells of the intestinal villi and enter the lacteals and
blood-vessels. The only purely physical facts which throw
any light upon this phenomenon are those of the passage of
emulsions through membranes moistened with alkaline
fluids. Excessively fine emulsions actually penetrate the
intestinal vessels and the structures which cover them ; and
the fluids contained in these vessels are always distinctly al-
kaline. How far the epithelial cells covering the villi are
concerned in this process is a question which cannot at
present be satisfactorily answered.

It is true, as a general law, that insoluble substances,
with the exception of the fats, are never regularly absorbed,
no matter how finely they may be divided. The apparent
exceptions to this are, mercury in a state of minute sub-
division like an emulsion, and carbonaceous particles. In the

1 D ALTON, Treatise on Human Physiology, Philadelphia, 1864, p. 172.

2 KOLLIKER, IOC. Clt.

464 ABSORPTION.

case of mercury, it is well known that minute particles in
the form of unguents may be introduced into the system by
prolonged frictions ; but this cannot be regarded as an in-
stance of physiological absorption. - We have already con-
sidered the subject of the passage of small carbonaceous
particles through the pulmonary membrane, and have seen
that their penetration is purely mechanical.1 The same thing
may possibly occur when fine sharp particles of carbon are
introduced into the alimentary canal ; but the experiments
of Mialhe with pulverized charcoal,2 and particularly those
those of Berard, Robin, and Bernard with lamp-black intro-
duced into the intestinal canal of animals, showed that
though the intestinal mucous membrane became of a deep
black, this could easily be removed by a stream of water,
and no carbonaceous particles could be discovered in the
mesenteric veins, the lacteals, or the mesenteric glands.3
When the carbon is used in the form of lamp-black, the
particles are very minute and rounded, and do not present
the sharp points and edges which sometimes enable the
grains of pulverized charcoal to penetrate the vessels me-
chanically.

Variations and Modifications of Absorption.

Yery little is known concerning the variations in lacteal
or lymphatic absorption ; but in absorption by blood-vessels,
important modifications occur, due, on the one hand, to dif-
ferent conditions of the fluids to be absorbed, and on the
other, to differences in the constitution of the blood and in
the conditions of the vessels.

The different conditions of the fluids to be absorbed ap-
parently do not always have the same influence in physio-
logical absorption as in endosmotic experiments made out
of the body. Saccharine solutions of different densities con-

1 Yol. i., Kespiration, p. 364.

• 2 MIALHE, Ghimie appliquee d la Physiologic, Paris, 1856, p. 197.
8 BEKARD, Cours de Physiologic, Paris, 1849, tome ii., p. 729.

VARIATIONS AND MODIFICATIONS OF ABSOKPTION. 465

fined in distinct portions of the intestinal canal of a living
animal do not present any marked variations in the rapidity
of their absorption, and they are taken up by the blood, even
when their density is greater than that of the blood-plasma.
Solutions of nitrate of potash and sulphate of soda of greater
density than the serum, which would, therefore, attract the
endosmotic current in an endosmometer, are readily taken
up by the blood-vessels in a living animal.1 Indeed, nearly
all soluble substances, whatever be the density of their solu-
tions, may be taken up by the various absorbing surfaces
during life.

The woorara poison and most of the venoms are remark-
able exceptions to this rule. In a series of very interesting
experiments upon the absorption of woorara, Bernard has
shown that this curious poison, which is absorbed so readily
from wounds or when introduced under the skin, generally
produces no effect when introduced into the stomach, the
small intestine, or the urinary bladder. This result, how-
ever, is not invariable, for poisonous effects are produced
when the agent is introduced into the stomach of a fasting
animal.2 This peculiarity in the absorption of many of the
animal poisons has long been observed ; and it is well known
that flesh of animals poisoned with woorara can be eaten
with impunity. It is curious, however, to see an animal
carrying in the stomach without danger a fluid which would
produce death if introduced under the skin ; and the ex-
planation of this is not readily apparent. The poison is
not neutralized by the digestive fluids, for woorara digested
for a long time in gastric juice, or taken from the stomach
of a dog, is found to possess all its toxic properties, as we
have frequently shown (repeating the experiment of Ber-
nard) by poisoning a pigeon with woorara drawn by a fis-
tula from the stomach of a living dog. If we recognize the

1 LOXGET, Traite de Physiologic, Paris, 1861, tome L, p. 921.

2 BERNARD, Lemons sur les Effets des* Substances Toxiques et Medicamenteuses,
Paris, 1835, p. 282 et seq.

30

466 ABSORPTION.

absorption of this poison simply by its effects npon the sys-
tem, it must be assumed that, during digestion, it cannot be
absorbed by the mucous membrane of the stomach and small
intestine, notwithstanding that it is exceedingly soluble.

It has also been shown by Segalas, that liquids which
immediately disorganize the tissues, such as concentrated
nitric or sulphuric acid, cannot be absorbed.1 Another
important peculiarity in absorption has been demonstrated
by Mialhe, who has shown that solutions which readily co-
agulate the albumen of the circulating fluids are absorbed
very slowly.2 This is explained on supposition that there is
a coagulation of the albuminous fluids with which the ab-
sorbing membrane is permeated, which interferes with the
passage of liquids. These substances are nevertheless taken
up by the blood-vessels, though rather slowly.

The modifications which are due simply to the physical
conditions of liquids to be absorbed are chiefly manifested
out of the body, and will be considered in connection with
the subject of endosmosis.

Influence of the Condition of the Blood and the Vessels on
Absorption. — After loss of blood or deterioration of the nutri-
tive fluid from prolonged abstinence, absorption generally
takes place with great activity. This is well known, both as
regards the entrance of water and alimentary substances and
the absorption of medicines. It was at one time quite a com-
mon practice to bleed before administering certain remedies,
in order to produce their more speedy action upon the sys-
tem. The increase in the activity of the absorption of poi-
sons by bleeding was strikingly illustrated by Magendie in
some of his earliest experiments. He found that when an
animal had been bled copiously, the effects of poisons, which
were ordinarily manifested after two minutes, appeared with-

1 SEGALAS, Note sur quclques Points de Physiologic. — Journal de Physiologie^
Paris, 1857, tomeiv., p. 287.

2 MIALHE, Chimie appliquee d la Physiologic, Paris, 1856, p. 200.

INFLUENCE OF THE NEKVOTJS SYSTEM ON ABSORPTION. 467

in thirty seconds.1 In the same series of experiments, the
effects of excessive repletion of the vessels were demonstra-
ted. After injecting about a quart of water into the veins
of a dog of medium size, absorption was found to be con-
siderably retarded; and in another experiment, in which
more than two quarts of water were thus introduced (as
much as could be injected without producing death) the ab-
sorption of poisons seemed to be arrested ; and after having
waited half an hour for the phenomena which were generally
developed in two minutes, a large opening was made in the
jugular vein, and as the vessels became relieved, the toxic
effects were manifested.2

The rapidity of the circulation has an important influence
upon absorption. We have already shown, in treating of the
action of the blood-vessels on absorption, that this process
may be impeded or even arrested by the ligation of important
vessels. It has been evident, also, that absorption is generally
active in proportion to the vascularity of different parts.
During ,the process of intestinal absorption, the increase in
the activity of the circulation in the mucous membrane
is very marked, and undoubtedly has its influence upon the
rapidity with which the products of digestion are taken up.

Influence of the Nervous System on Absorption. — Experi-
ments upon the influence of the nervous system on absorption
are still very imperfect. It is certain that this process, espe-
cially in the stomach, is subject to variations, which can
hardly be dependent upon any thing but nervous action.
Water and other liquids, which usually are readily absorbed
from the stomach, are sometimes retained for a time, and are
afterward rejected in nearly the condition in which they were
taken. It is probable, however, that the most important in-
fluences thus exerted by the nervous system are effected

1 MAGENDIE, Memoire sur le Mechanisme de T Absorption chez les Animaux d
Sang rouge et chaud. — Journal de Physiologic, Paris, 1821, tome i., p. 5.
a MAGENDIE, loc. cit.

468 ABSORPTION.

through the circulation. The recent experiments of Bernard
and others upon the sympathetic system of nerves and its
connection with the muscular coats of the small arteries, by
the action of which the supply of blood in different parts is
regulated, point out a line of experimentation which would
probably throw much light upon some of the important vari-
ations in absorption. "When it is remembered that the small
arteries may become so contracted under the influence of the
sympathetic system, that their calibre is almost obliterated,
of course retarding to a corresponding degree the capillary
and venous circulation in the parts, and, again, that through
the sympathetic nerves the same vessels may be so dilated as
to admit to a particular part three or four times as much
blood as it ordinarily receives, it becomes apparent that ab-
sorption may be profoundly affected through this system of
nerves. Unfortunately, there are as yet no definite experi-
ments upon these points. In the observations upon absorp-
tion after division of certain nerves by Brodie, Brachet, Lon-
get, and others, attention was always directed particularly to
the cerebro-spinal system, and many of the experiments, in-
deed, were made before much was known concerning the
functions of the sympathetic.

As far as the influence of the cerebro-spinal system is
concerned, it has been ascertained that while section of
some of the nerves distributed to the alimentary canal will
slightly retard the absorption of poisonous substances, it is
never entirely arrested. Longet found that the operation of
strychnine injected into the stomach of a dog in which both
pneumogastric nerves had been divided was retarded about
five minutes ; but that the convulsions, when they occurred,
were fully as severe as in an animal which had received an
equal dose, without section of the nerves.1

1 LONGET, 2raite de Physiologic, Paris, 1861, tome i., p. 379.

CHAPTEK XYI

I

IMBIBITION AND ENDOSMOSIS.

General considerations — Imbibition by animal tissues — Mechanism of the passage
of liquids through membranes — Observations anterior to those of Dutro-
chet — Experiments of Dutrochet — Conditions necessary to endosmosis and
exosmosis — Influence of membranes upon osmotic currents — Capillary attrac-
tion— Imbibition by porous substances — Endosmosis through porous septa —
Endosmosis through animal membranes — Endosmosis through liquid septa —
Electrical theory of endosmosis — Influence of different liquids upon osmotic
currents — Diffusion of liquids — Endosmotic equivalents — Modifications of en-
dosmosis— Modifications due to the extent and the thinness of the permeable
membrane — Modifications due to pressure and the movements of liquids —
Modifications due to variations in temperature — Modifications induced by elec-
tricity— Application of physical laws to the function of absorption — Transu-
datron.

THE ideas of physiologists concerning the mechanism of
absorption have become radically changed since the begin-
ning of the present century ; and it is now generally admitted
that this process takes place chiefly by blood-vessels, and that
the absorbents have no orifices endowed with the wonderful
elective power which was attributed to them by the older wri-
ters. This involves the passage of liquids through the coats
of the blood-vessels and lymphatics ; a process which has been
the subject of numerous experiments, resulting in the devel-
opment of many important physical laws capable of applica-
tion to physiological absorption. At the present day, the
history of absorption is not complete without a consideration
of the laws of imbibition and endosmosis. In accordance
with the plan which we have endeavored to follow in the

470 ABSORPTION.

course of this work, we shall only consider fully those facts
in the history of endosmosis which are directly applicable to
absorption as it takes place in the living organism ; necessa-
rily omitting many points which may be interesting, but
which have no direct physiological application. It is impor-
tant, however, to ascertain precisely how far these physical
laws are involved in the passage of liquids through living
membranes.

In entering upon the consideration of this subject, it is
necessary to appreciate the fact that the walls of the blood-
vessels and lymphatics have no pores which are demonstra-
ble ; and the supposition that minute orifices exist in these
membranes, that cannot be discovered by the highest powers
of the microscope, is entirely gratuitous, and has only been
advanced for the purpose of affording a purely physical ex-
planation of the passage of liquids.

It is evident that if liquids be capable of passing through
the substance of animal membranes, the membrane itself is
capable of taking up a certain portion of the liquid by imbi-
bition ; and this must be considered as the starting-point in
absorption.

Imbibition is, indeed, a property common to all animal
structures. One of the m^st striking characteristics of or-
ganic principles is that they may lose water by desiccation
and regain it by imbibition. It is also a well-known fact
that the tissues do not imbibe all solutions with the same
degree of activity. The researches of Liebig have shown
that distilled water is the liquid which is always taken up in
greatest quantity, and that saline solutions enter the sub-
stance of the tissues in an inverse ratio to their density.1
This is also the fact with regard to mixtures of alcohol and
water ; imbibition always being in an inverse proportion to
the quantity of alcohol present in the liquid. Among the

1 LIEBIU, Recherches sur quelques-unes des Causes du Mouvement des Liquidcs
dans l> Organism? Animal — Annalcs de CMmieet de Physique, Paris, 1849, 3me
s6rie, tome xxv., p. 367.

IMBIBITION AND ENDOSMOSIS. 471

other circumstances which have a marked influence upon
imbibition, is temperature. It is a familiar fact that dried
animal membranes may be more rapidly softened in warm
than in cold water ; and with regard, to the imbibition of
liquids by sand, the researches of Matteucei and Cima have
shown an immense increase at a moderately elevated tem-
perature.1 While nearly all the structures of the body
will imbibe liquids, after desiccation, the membranes through
which the processes of absorption are most active are, as a
rule, most easily permeated; and we shall see when we
come to study the mechanism of the passage of liquids
through these membranes, that the character of the liquid,
the temperature, etc., have a great influence upon the activ-
ity of this process. For example, all liquids which have a
tendency to harden the tissues, such as saline solutions, alco-
hol, etc., pass through with much less rapidity than pure
water. These facts will be found particularly interesting in
connection with experiments on the passage of liquids
through membranes, in experiments on endosmosis with arti-
ficial apparatus.

Mechanism of the Passage of Liquids through Membranes.

The attention of physiologists was first directed to this-
subject by the researches of Dutrochet, in 1826.2 Though
not by any means the first to observe the phenomena which
he described under the name of endosmosis, to Dutrochet is
generally ascribed the honor of having first indicated the
applications of the laws of endosmosis to the nutrition of
plants and animals. Undoubtedly, Dutrochet was the first

1 MATTEUCCI, Lemons sur les Phenomenes Physiques des Corps. Vivants, Paris,
1847, p. 23.

2 The most complete account of these experiments is contained in a collection
of memoirs published by Dutrochet, in 1837, entitled Memoires pour servir d
VHisloire Anatomique et Physiologique des Vegetaux et des Animaux, tome i., pp.
1-99. A pretty full account is also given by Dutrochet in the Cyclopaedia of
Anatomy and Physiology, article Endosmosis, London, 1836-1839, vol. ii., p. 98.

472 ABSORPTION.

to make experiments upon endosmosis which attracted
the attention of scientific men in different parts of the
world and were immediately repeated and extended; but
the experiments made upon living animals by Lebkiichner,
in 1819, and by Magendie, in 1820, had already demon-
strated most conclusively the passage of liquids through the
walls of the blood-vessels ; and the explanation offered by
these physiologists was fully as definite as that proposed
by Dutrochet.

In the experiments of Lebkiichner, it was conclusively
shown that solutions readily passed through- many ani-
mal membranes, especially the walls of the blood-vessels.
He found that prussiate of potash, placed in contact with
the jugular vein of a living rabbit for ten minutes, pene-
trated into the blood, so that the characteristic reactions with
the sulphate of iron were manifested in the serum of the
arterial blood and the blood from the jugular upon the oppo-
site side. The same result followed other experiments of the
same kind, and experiments with emetic, prussic acid, etc.1

In the experiments of Magendie, this observer, refusing
to recognize the existence of absorbing openings, either in
the lacteals or the venous radicles, showed that when a por-
tion of the jugular vein was plunged into acidulated water,
and was so arranged that none of the fluid could enter ex-
cept through its walls, pure water, when passed in a stream
through the vessel, became sensibly acid in from five to six
minutes. Another experiment was even more interesting.
He exposed in a young dog the jugular vein for its whole
length, placed it upon a card, and let fall drop by drop upon
its surface a solution of nux vomica, taking care that the
poison touched nothing but the card and the vein, and that
the course of the blood in the vessel was not • interrupted.
The effects of the poison were developed in this animal in four

J LEBKUCHNER, Dissertation inaugurate sur la Permeabilite des Tissus vivans,
Tubingue, 1819. (Extrait.)— Archives Generates de Mededne, Paris, 1825, tome
vii., p. 439.

PASSAGE OF LIQUIDS THROUGH MEMBRANES. 473

minutes. This experiment was repeated upon other animals
and upon the carotid artery, with similar results.1 These
observations are referred to in recent French works on phys-
iology, as the first experiments illustrating the operation of
imbibition in the process of absorption ; 2 but we cannot dis-
cover why they do not fully illustrate the passage of liquids
through the membranes which form the walls of the blood-

o

vessels. If they had been made after the experiments of
Dutrochet, instead of before, they would certainly have been
quoted as illustrations of endosmosis.

As regards experiments on the passage of liquids through
membranes, out of the body, those made by the Abbe
Nollet, in 1748 (probably the first on record), are most strik-
ing, when brought in comparison with the illustrative experi-
ments made on endosmosis at the present day.

In the course of a series of observations on the causes Of
the ebullition of liquids, ISTollet filled a vial about five inches
long with alcohol, covered it tightly with a moistened blad-
der, and immersed it in pure water. In five or six hours, he
found that the water had passed through the membrane to
the alcohol, and the bladder had become convex. It first
occurred to him that this might be due to a difference in the
temperature of the two liquids ; but the same phenomenon
was presented when the temperature of the liquids was the
same. On filling the vial with water and immersing it in
alcohol, the action was reversed, and the membrane became
concave. By a series of ingeniously contrived experiments,
he also ascertained that water could readily be forced through
a membrane, while alcohol passed through in small quantity
and only under great pressure.3

1 MAGENDIE, Memoire sur le Mecanisme de I1 Absorption chez les Animaux d
Sang rouge ei chaud, lu d VAcademie des Sciences de Paris, octobre, 1820. —
Journal de Physiologic, Paris, 1821, tomei., p. 1 et seq.

2 MILNE-EDWARDS, Lecons sur la Physiologic, Paris, 1859, tome v., p. 25; and
LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 381.

3 NOLLET, Recherches sur les Causes du Bouillonnement des Liquides. —
Memoir es de VAcademie Royale, Paris, 1748, p. 101 et seq.

474 ABSOKPTION.

From the beginning of the present century, up to 1826,
several isolated observations were made on the passage of
liquids through membranes. In 1802, Parrot noted the
passage of water through the membranes of an egg which
had no calcareous covering ; 1 in 1816, Porrett noted that the
galvanic current was capable of causing water to pass through
an animal membrane ; 3 and finally, in 1822, Fischer, pro-
fessor at Breslau, actually constructed an endosmometer, and
noted the elevation of the liquid in the tube above the level
of the liquid in which the apparatus was placed. The experi-
ments of Fischer were more complete, and illustrated the
laws of endosmosis more fully, than is generally supposed.
Not only did he construct an endosmometer, closing the
lower portion of his apparatus with an animal membrane,
and noting the passage of pure water through the membrane
to a saline solution, but he described the exosmosis of
the saline solution, and observed that the currents continued
until both liquids became of equal density. He also noted
that the currents were active in proportion to the thinness
of the animal membrane used.3

To return to the observations of Dutrochet, it is univer-
sally acknowledged that he was the first to describe fully
and definitely the passage of liquids through animal mem-
branes, out of the body ; to show the influence of different
liquids used ; to measure the force of the different currents ;
and, finally, to give to these actions the names of endosmosis
and exosmosis.4 He constructed an instrument known as

1 PARROT, Phenomene frappant d^Endosmose dans P Organization animate.
—Bulletin ScientifiquG de V Academic de St. Petersbourg, 1840, tome vii., p. 346.

2 PORRETT, Curious Galvanic Experiments. — Annals of Philosophy, London,
1816, vol. viii.,p. 74.

3 FISCHER, Ueber die Wiederherstellung eines Metalls durch ein anderes und
iiber die Eigenschaft der thierisclien JBlase Flussigkeiten durch sicli hindurch zu
lassen, und sie in einigen Fallen aw2«7i£&m.— GILBERT'S Annalcn der Physik,
Leipzig, 1822, Bd. kxii., S. 301.

4 DUTROCHET, De I* Endosmose. — Memoires pour servir d VHistoire Anato-
mique et Physiologique des Animaux, Paris, 1837, tome i., p. 1 et seq.

Dutrochet was first led to study the phenomena of endosmosis by observing

PASSAGE OF LIQUIDS THEOUGH MEMBEANES. 475

the endosmometer ; which consists simply of a small bell
glass, the lower opening of which is closed by a membrane,
the opening above being connected with a long glass tube
by which the force with which liquids pass through the
membrane can be measured. The bell-glass is generally filled
with a liquid capable of attracting a current of water from
without, and is immersed in pure water, so that the membrane
is completely covered. Under these circumstances, there is
a current of water through the membrane, which will cause
the liquid to mount in the tube, sometimes to the height of
•several feet; but at the same time, there is a feebler current
from the interior of the apparatus to the water. Dutrochet
called the stronger, the endosmotic current, and the feebler,
the exosmotic current. This nomenclature, however, is not
strictly accurate ; for if the position of the liquids be re-
versed, as was shown in the old experiments of Nollet, the
stronger current is exosmotic and the feebler is endosmotic.
It must be remembered, therefore, that the name endosmosis
is always to be understood as applied to the principal cur-
rent, while the term exosmosis is applied to the current in
the opposite direction. This possible inaccuracy of expres-
sion has led to the adoption by Graham and others of the
term osmosis, as applied generally to the currents which take
place through membranes ; a but the terms first proposed by
Dutrochet are most commonly used.

The phenomena of endosmosis, w^hich, since the publica-
tion of the researches of Dutrochet, have been so closely
studied by physicists, are chiefly interesting to the physiolo-
gist in their application to absorption. "While it is perhaps
true that all the phenomena of physiological absorption

that little organic vesicles, when immersed in water, discharged a portion of their
contents through their investing membranes. This fact he communicated to the
Philomathic Society of Paris, in 1809 (pp. cit., p. 5), but as we have already seen,
essentially the same phenomenon was observed in an egg by Parrot, in 1802.

1 GRAHAM, On Osmotic Force. — Philosophical Transactions, London, 1854, p.
177 et seq.; and Elements of Inorganic Chemistry, Philadelphia, 1858, p. 746.

476 ABSORPTION.

cannot as yet be explained upon purely physical principles,
it is nevertheless important to ascertain how far physical
laws are involved in this process. With this end in view,
we shall study the physical phenomena of endosmosis, chiefly
with reference to their physiological applications.

It is now definitely ascertained that the following condi-
tions are necessary for the operation of endosmosis and exos-
mosis :

1. That both liquids be capable of " wetting " the inter-
posed membrane, or, in other words, that the membrane be
capable of imbibing both liquids. If but one of the liquids
can wet the membrane, the current can take place in only
one direction.

2. That the liquids be miscible with each other, and be
differently constituted. Though it is found that the currents
are most active when the liquids are of different densities, this
condition is not indispensable ; for currents will take place
between solutions of different substances, such as salt, sugar,
or albumen, though they may have precisely the same den-
sity.

The physiological applications of the laws of endosmosis
can now be more fully appreciated, as it is evident that the
above conditions are fulfilled whenever absorption takes
place ; with the single exception of the absorption of fats,
which has been specially considered. For example, all sub-
stances are dissolved or liquefied before they are absorbed,
and in this condition are capable of "wetting the walls of the
blood-vessels ; and all the liquids absorbed are capable of
mixing with the plasma of the blood.

What makes this application still more complete is the
behavior of albumen in endosmotic experiments. In phys-
iological absorption, there is always an immense predomi-
nance of the endosmotic current, and there is very little
transudation, or exosmosis, of albumen, the chief nutritive
constituent of the blood. On the other hand, there is a con-
stant absorption of albuminose, which is destined to be con-

PASSAGE OF LIQUIDS THROUGH MEMBRANES. 477

verted into the albumen of the blood. Mialhe, in com-
paring the endosrnotic properties of albumen and albumi-
nose, has given an explanation of these remarkable phe-
nomena.

Recognizing the fact, which was, indeed, pointed out
clearly by Dutrochet, that albumen is capable of inducing a
more powerful endosmotic current than almost any other
liquid, he has shown that it never itself passes through mem-
branes in the exosrnotic current ; but that albuminoids, after
transformation by digestion into albuminose, or albumen
mixed with gastric juice, pass through animal membranes
with great facility. The experiments by which these facts
are demonstrated are very conclusive, and are of the highest
physiological importance. On removing part of the shell of
an egg, so as to expose its membranes, and immersing it in
pure water, the passage of water into the egg was rendered
evident by the projection of the distended membranes ; but
although the surrounding liquid had become alkaline, and
the appropriate tests revealed the presence of some of the in-
organic constituents of the egg, the presence of albumen
could never be detected.1 When the contents of the egg
were replaced by the serum of the blood, the same result fol-
lowed. " After six or eight hours of immersion, the serum
had yielded to the water in the vessel all its saline elements,
chlorides, sulphates, phosphates, which were easily recog-
nized by their peculiar reactions, but not an atom of al-
bumen." 2

1 MIALHE, Chimie appliquee d la Physiologic et d la Therapcutique, Paris,
1856, p. 141.

2 Loc. tit., p. 142.

The above experiment possesses additional interest, as it illustrates a new
principle recently announced by Graham, called dialysis. This is dependent simply
upon the fact that various membranes and some porous septa, when used in an
apparatus like an endosmometer, will allow only " crystalloid " bodies to pass
through ; while the organic substances, called by Graham " colloids," are retained.
For example, if a fluid containing an inorganic substance, such as a salt of arsenic,
mixed with organic matter, be placed in the interior of such an apparatus, and

478 ABSOKPTKXN-.

Influence of Membranes upon Osmotic Currents.

The force with which liquids pass through membranes,
called endosmotic or osmotic force, is to a great degree de-
pendent upon the influence of the membranes themselves.
This influence is always purely physical, in experiments
made out of the body ; and physiological absorption can be
explained, to a certain extent, by the same laws. It must be
remembered, however, that the properties of organic struc-
tures, which are manifested only in living bodies, are capable
of modifying these physical phenomena to a remarkable de-
gree. For example, all living tissues are capable of selecting
and appropriating from the nutritive fluids the materials ne-
cessary for their regeneration ; and the secreting structures of
glands also select from the blood certain principles which are
used in the formation of their secretions. At the present day
these phenomena, and their modifications through the ner- .
vous system, cannot be fully explained. This is true, also,
of many of the phenomena of absorption and their modifica-
tions, which are probably dependent upon the same kind of
action. In view of these undoubted facts, the influence of
the structures through which liquids pass in physiological ab-
sorption may be divided : first, into physical influences, which
may be illustrated by endosmotic experiments with organic
membranes out of the body ; and second, modifications of
these phenomena, which are presented only in the living
organism.

One of the earliest theories which was offered in expla-
nation of the passage of liquids through membranes, makes
it dependent . entirely upon the laws of capillary attraction
and of the diffusion of liquids ; and to appreciate fully the
views of those who adopt this purely physical theory, it will

the whole be immersed in pure water, in the course of about twenty-four hours,
one-half or three-fourths of the crystalloid matters will be found in the surround-
ing liquid, entirely separated from the colloid matters. An apparatus of this
land, called a dialyser, has been found very useful in certain inorganic analyses.

INFLUENCE OF MEMBRANES UPON OSMOTIC CURRENTS. 479

be necessary to pass in review the laws which regulate these
phenomena. This is all the more necessary, as in most works
upon physics, the physiological application of these laws are
not fully appreciated ; while, on the other handj physiol-
ogists are too apt to neglect physical explanations of the so-
called vital phenomena.

Capillary attraction is dependent upon an adhesive force
or attraction between certain surfaces and certain liquids. A
liquid, in order to be subject to this force, must be capable
of wetting the surface to which it is exposed. This is illus-
trated by the well-known attraction between water and
glass. If a drop of water be placed upon a clean glass plate,
it becomes flattened and adheres to the surface ; and when
the plate is inclined, runs to the edge, leaving a wet line, and
does not fall to the ground, but adheres to the plate and is
sustained against the force of gravity. If the plate be care-
fully covered with grease, the drop of water will not adhere
to the surface, and is more nearly spherical ; and when the
plate is inclined, it rolls to the edge and falls to the ground.
This is explained by the fact that water is not capable of
wetting a greased surface. If a globule of mercury be placed
upon the glass plate, instead of water, it moves about freely,
and falls to the ground, because no attraction exists between
it and the surface.

If the experiment be now modified by partly immersing
a clean glass plate in a vessel of water, another set of phenom-
ena is presented. At the point where the glass is in contact
with the surface of the liquid, a slight elevation of water along
the sides of the glass will be observed, which is in opposition
to both the force of gravitation and the cohesive molecular
attraction between the particles of the liquid. No argument
is necessary to show that, within certain limits imposed by
the law of gravitation, the ascent of liquids thus attracted by
the surfaces of solids will bear a direct ratio to the predomi-
nance of the adhesive attraction between the surface and the
liquid over the cohesive attraction between the molecules of

4:80 ABSOBPTION.

the liquid. The elevation of the liquid can therefore be in-
creased by diminishing the amount of liquid and increas-
ing the extent of the attracting surface. This is illustrated
by a modification of the last experiment. If the surface -of
the liquid near the plate of glass be carefully examined, it
will be found to present a curve, which extends from the
highest point to which the liquid has ascended on the glass
to the general level. If we now divide the liquid into im-
aginary parallel strata of infinite thinness, it is evident that
the layer of liquid next the glass is most powerfully attracted
and has mounted highest ; that the second stratum, being
removed from the surface, is less powerfully attracted, and is
influenced to a greater degree by the cohesive attraction be-
tween the molecules of the liquid ; and that, as we recede
from the glass surface, the attractive force is progressively
diminished and the cohesive force progressively increased,
until, when the general level of the liquid is reached, the at-
tractive force is lost. Suppose now that a second plate of
glass be placed parallel to the first, the liquid between the
two plates will be subjected to double the amount of attrac-
tion, and will form a concave surface, the lowest point being
equidistant between the two plates. The nearer these two
plates are brought together, the smaller will be the quantity
of liquid, and the molecular attraction between its particles
will necessarily be proportionately diminished. This may
be shown by approximating the glasses at one end, and
progressively increasing the distance between them to the
other. The liquid will then form a curve between the plates,
the highest point being where they are most closely approx-
imated.

If tubes be used instead of plates of glass, the foregoing
facts are more strikingly illustrated. The nearer the internal
surfaces of. the tube are brought together, or, in other words,
the smaller the calibre of the tube, the greater will be the
elevation of liquid in its interior. It is because liquids are
observed, in accordance with this law, to mount highest in

INFLUENCE OF MEMBRANES UPON OSMOTIC CURRENTS. 481

tubes of capillary diameter, that this force has been called
capillary attraction.

There is no essential difference between the phenomena
of imbibition by porous substances and the elevation of
liquids in capillary tubes. In both, it is necessary that the
liquid should be capable of wetting the surfaces to which it
is exposed. The imbibition of water by a sponge is depend-
ent upon capillary attraction. If the liquid thus taken up
remain and fill the interstices, no current takes place ; but
if it be constantly removed by evaporation, or otherwise,
a constant now is produced. It is in this way that an
alcohol-lamp is emptied of fluid, which is taken up by the
wick and lost by evaporation. This single current is pro-
duced by the diffusion of the liquid in the atmosphere in the
form of vapor • but if an apparatus be constructed in which
the liquid absorbed is gradually diffused in another liquid,
the result will be the same. Suppose, for example, that an
endosmometer be constructed in which the septum consists of
a porous substance, such as unglazed earthenware. Let this
apparatus be so filled with a saline solution, and the septum
immersed in pure water. The porous septum will then
gradually take up the water and bring it in contact with the
saline solution ; when, in obedience to the law of diffusion
of liquids, the water passes in a diffusive current to the saline
solution, and a steady current wUl be established through
the septum. As diffusion can only take place between liquids
which are miscible with each other, this condition is indis-
pensable to the production of a current. If we now suppose
that both liquids are capable of wetting the septum, in such
an apparatus as we have described, they will meet in the
substance of the septum. Once in contact with each other,
whether within or without the septum, the liquids will
diffuse ; the water flowing toward the saline solution, which
in its turn flows toward the water. In this way, two currents
are produced. It has been found in experiments of this kind
that the two currents are generally unequal, the more power-
31

482 ABSOKPTION.

ful corresponding to the endosmoticj and the feebler to the
exosmotic current. This inequality in the currents is explain-
ed by the fact that porous substances imbibe different liquids
with different degrees of activity ; * so that the septum
always contains a greater quantity of one of the liquids.
It is the liquid thus introduced in greater quantity in
which the more powerful current is developed. In this case,
also, the difference in the diffusibility of the liquids has
an important influence ; but these phenomena will be more
fully considered when we come to treat of the influence of
different liquids upon endosmosis.

Numerous experiments have demonstrated that both -the
endosmotic and the exosmotic current may be produced by
using a porous instead of a membranous septum, though
they are always more feeble.2 The phenomena thus pre-
sented are to be explained entirely by the laws of capil-
lary attraction and of the diffusion of liquids. These laws
would enter largely into the explanation of the passage of
liquids through animal membranes, if it could be demon-
strated, or even rendered probable, that these membranes
are porous, or are provided with capillary openings. It will
be necessary, however, to study this question very carefully,

1 This fact is strikingly illustrated in some of the experiments of Matteucci
on the imbibition of different solutions by tubes filled with fine sand (Lecons sur
les Phenomenes Physiques des Corps Vivants, Paris, 184*7, p. 21).

2 DUTROCHET, De rjj/ndosmose. — Memoires pour servzr d VHistoire Anato-
mique el Physiologique des Vegetaux et des Animaux, Paris, 1837, tome i., pp.
21-23.

Dutroehet made a number of experiments with different porous septa. He
found it impossible to produce endosmosis through thin sections of sandstone
or of imperfectly baked porcelain ; but with a septum of potter's clay, one-
twenty-fifth of an inch thick, there was a tolerably energetic endosmotic current.
The same result followed when the septum was from one-twelfth to one-fifth of
an inch thick ; but in septa of greater thickness than this, the currents were
very feeble. These experiments were repeated by Graham with more satisfac-
tory results. By employing a porous jar, such as is used in Grove's battery,
vigorous endosmotic and exosmotic currents were produced. — (On Osmotic Force*
— Philosophical Transactions, London, 1854, p. 180.)

INFLUENCE OF MEMBRANES UPON OSMOTIC CURRENTS. 483

and examine all the properties of animal membranes, both
within and without the living organism.

In the first place, is there any proof that all membranes
which will admit the passage of liquids are porous ? This
is a most important question ; and it lies at the foundation of
the explanation of the phenomena of endosmosis by the laws
of capillary attraction.

In all membranes which possess an anatomical structure
discoverable by the microscope, there are undoubtedly inter-
stices between the fibres, cells, etc., of which the tissue is
composed ; but on the other hand, animal membranes gen-
erally have a layer, like the basement-membranes of mucous
tissues, which is absolutely homogeneous and structureless.
In applying the laws of endosmosis to physiological absorp-
tion, it is found that the membranes which are most easily
penetrated by fluids are excessively thin and perfectly homo-
geneous. Take, for example, the walls of the capillary blood-
vessels, through which the greatest part of the physiological
absorption takes place ; this membrane is from jj^oo- to Tsio-ir
of an inch thick, and is entirely amorphous, with the excep-
tion of a few oval nuclei imbedded in its substance. The as-
sumption that invisible capillary orifices exist in these thin
amorphous membranes is purely hypothetical, and is unwar-
rantable. The only circumstance which could lead to such
a supposition is the fact that these membranes can be pene-
trated by liquids.

It is manifestly unphilosophical and absurd to offer, as an
explanation of endosmosis through structureless membranes,
an hypothesis which has its only support in the existence of
the phenomenon which it is intended to explain. This mode
of reasoning is all the more unsound, as the phenomena of
endosmosis are very far from being completely understood ;
and many important properties of organic structures, which
bear directly upon the question under consideration, are ig-
nored. For example, physiological absorption does not
always take place in accordance with known physical laws.

484: ABSORPTION.

It undergoes modifications which can at present only be
explained on the supposition that the liquids become, for
the time, part of the living organic structures and partake
of their peculiar properties ; one of them, the property
by virtue of which they appropriate both the 'organic and
Ithe inorganic principles necessary to their proper consti-
tution and regeneration, is called by some, vital ; a word
which simply expresses ignorance of its essential character.
It must be understood, however, that this remark does not
apply to the general phenomena of endosmosis or absorp-
tion, but only to certain of its unexplained modifications.

A most important property of organic tissues, which is
ignored by those who explain absorption on the principle of
capillary attraction, is that of hygrometricity. All the or-
ganic nitrogenized proximate principles are capable of losing
their water of composition by desiccation and of regaining it
by imbibition. The water w^hich enters into their composi-
tion is not necessarily contained in interstices in the tissue,
but, in the case of structureless parts especially, is uniform-
ly disseminated, or we may term it diffused, throughout
the organic substance, of which it forms a constituent part.
This action of certain liquids upon the organic semisolids is
something like the diffusion of liquids ; the difference being
that it is the liquid only which is diffused in the semisolid,
the semisolid being incapable of diffusing in the liquid.1 As
it has been found that all liquids are not equally subject to
capillary attraction, so animal tissues imbibe different liquids
with different degrees of activity ; 2 a fact which will ac-
count in a measure for the variations in the endosmotic
currents with different solutions.

Examples are not wanting of endosmosis by imbibition
or diffusion, when it cannot be assumed that there is any

1 The liquid organic principles, such as albumen and caseine, are capable of
diffusing with other liquids, but the cohesion of membranes is too powerful to
allow of this reciprocal action.

2 See pnge 470.

INFLUENCE OF MEMBRANES UPON OSMOTIC CURRENTS. 485

such thing as porosity in the septum. The following exper-
iment of Lhermite fully illustrates this point. A tube was
partly filled with a column of chloroform ; and upon this was
poured a layer of water, and above it a layer of ether. The
ether gradually penetrated the layer of water and passed to
the chloroform, mingling with it. After a certain time, all
the ether had thus been diffused in the chloroform, and the
layer of water retained its original volume.1 We have re-
peated this experiment with some slight modifications, using
first a layer of sulphuric acid, then a layer of water, and
finally a solution of blue litmus in alcohol ; and in a very
short time the acid penetrated the water and reddened the
litmus above. A liquid septum is certainly not porous, in
any sense of the word ; and the explanation of the phenome-
non of endosmosis through liquids depends simply upon the
law of diffusion of liquids, the molecules of the liquids being
held together so feebly that they will admit the molecules of
other liquids with which they are capable of mixing.

With regard to the passage of liquids through different
septa, the following seem to be the facts which can be con-
sidered as definitely settled :

The cohesive attraction of the constituent particles of in-
soluble solids is so great, that the entrance of fluids is impossi-
ble, unless the substance be porous ; and this always involves
the law of capillary attraction ; but in liquids, the cohesive
attraction is so slight as to admit of the penetration and dif-
fusion of certain other liquids.

Homogeneous animal membranes, which are of a semi-
solid consistence, are capable of imbibing certain liquids ;
and any liquid which can pass into such membranes, under
proper conditions, will pass through them. The cohesive
attraction of the particles of the membrane is not such as to
allow them to imbibe an indefinite quantity of any liquid ;
but it is one of the distinctive properties of organic tissues

1 LHERMITE, Recherches sur V Endosmose. — Comptcs Rendus^axls, 1854, tome
xxxix., p. 1179.

486 ABSORPTION.

that a limited quantity of liquid can be taken up in this
way.

In view of these facts, it is not necessary to assume the ex-
istence of infinitely small capillary openings in homogeneous
membranes through which osmotic currents can be made to
take place, in order to explain the mechanism of these cur-
rents. In the case of two liquids capable of diffusing with
each other and separated by an animal membrane, the mech-
anism of the endosmotic and exosmotic currents is very
simple. In the first place, the membrane imbibes both the
liquids, but one is always taken up in greater quantity
than the other. If water and a solution of common salt be
employed, the surface of the membrane exposed to the water
will imbibe more than the surface exposed to the saline solu-
tion ; but both liquids will meet in its substance. The first
step, therefore, in the production of the currents is imbibi-
tion. Once in contact with each other, the liquids diffuse ;
the water passing to the saline solution, and vice versa.
This takes place by precisely the same mechanism which has
been described in connection with the passage of liquids
through porous septa.

In the observations of Porrett,1 it was observed that the
galvanic current was capable of causing water to pass
through animal membranes. Carrying out this idea, Dutixv
chet first supposed that the attractive force which operated
in endosmosis was due to electrical action ; but this view he
subsequently abandoned.2 This theory was afterward ad-
vanced by Draper,3 who noted the fact that a drop of water
placed upon the surface of mercury could be made to spread
out into a thin film and wet the mercury, by connecting the
globule with the positive pole of a galvanic battery and

1 PORRETT, Curious Galvanic Experiments. — Annals of Philosophy, London,
1816, vol. viii., p. 74.

2 Op. cit., p. 70.

3 DRAPER, On the Mechanical Functions of Areolar Tissues. — American Jour ••
nal of the Medical Sciences, August, 1838, p. 308.

INFLUENCE OF MEMBRANES UPON OSMOTIC CURRENTS. 487

the mercury with the negative pole. This experiment sim-
ply illustrates the fact that attractive force can be generated
by galvanic action. It is well known that endosmosis can
be greatly modified by galvanism, but the supposition that
capillary attraction is an electric phenomenon is purely hy-
pothetical and is entertained by few physicists. The numer-
ous publications by different experimenters, which immedi-
ately followed the publication of the observations of Dutro-
chet,1 many of them in this country, did little more than
confirm the facts demonstrated by Dutrochet, differing only
on theoretical points. A consideration of these, however,
belongs more to physics than to physiology.

It was first supposed by Dutrochet that the endosmotic
current always took place from the rarer to the denser li-
quid ; and it was found, in using different saline solutions,
that within certain limits, the activity of the current was
in proportion to the density of the solution in the endos-
mometer. But this error was soon corrected by more ex-
tended experiments, in which endosmotic currents frequently
took place from the denser to the rarer liquids, as is the case
with water and alcohol, and with alcohol and ether.2 It is
now fully recognized that the osmotic currents are not ne-
cessarily dependent upon the different densities of the liquids,
but are due chiefly to their different affinities for the in-
tervening membrane.

The osmotic currents may be modified with the same li-

1 TONGO, Experiments to prove the Existence of a peculiar Physico-organic Ac-
tion, inherent in Animal Tissues, called Endosmose and Exosmose. — American
Journal of the Medical Sciences, May, 1829, p. 73.

JACKSON, On Absorption, Ibid., Feb., 1830, p. 277.

MITCHELL, On the Penetrativeness of Fluids, Ibid., Nov., 1830, p. 36.

VALK, Microscopical Observations on Portions of Animal Tissue, with addi-
tional Experiments on Endosmose and Exosmose, Ibid., Feb., 1831, p. 405.
DRAPER, Experiments on Absorption, Ibid., May, 1836, p. 13. On the Phys-
ical Action of the Capillary Systems, Ibid., Feb., 1838, p. 289; and, On some Me-
chanical Functions of Areolar Tissues, Ibid., May, 1838, p. 23, and August,
1838, p. 302.

2 DUTROCIIET, Op. tit., p. 40.

488 ABSORPTION.

quids, by using different membranes. This fact was well illus-
trated in some of the experiments of Matteucci and Cinia, in
which comparative observations were made upon the currents
through the skin of the torpedo, the skin of the frog, and the
skin of the eel. The results obtained with these different
membranes showed marked and constant variations. The
same observers, in using the mucous membrane of the stom-
ach of the lamb, found a marked difference in the endosmot-
ic phenomena when the surface exposed to the water was
reversed. In two experiments, with the epithelial surface of
the membrane turned toward the interior of the endosmom-
eter, the elevation of the liquid in an hour and a quarter
was from forty-four to fifty-six millimeters; but with the
membrane reversed, so that the attached surface was turned
toward the interior, the elevations during the same period
were sixty-six and seventy-two millimeters.1 This difference
is readily explained by the difference in the constitution of
the two surfaces of the membrane used.

From these facts it is evident that while the diffusion of
liquids as they meet in the substance of a membrane is the
actual cause of the osmotic currents, which are continued as
the liquids diffuse with each other upon either side of the
membrane, the determination of a predominating or endos-
motic current, the ordinary conditions being undisturbed, is
effected by the greater attractive force which the membrane
exerts upon one of the liquids.

Influence of Different Liquids upon Osmotic Currents.

The action of the liquids between which endosmotic cur-
rents take place is, as we have seen, most intimately con-
nected with the force by which the liquids enter the mem-
brane, be it capillary attraction or imbibition ; but the at-
tractive force exerted by the membrane is never capable, in
itself, of producing a current. It is evident, therefore, that

1 MATTEUCCI, Lemons sur les Phenomenes Physiques des Corps Vivants^P&ris,
1847, pp. 48, 51.

INFLUENCE OF LIQUIDS UPON OSMOTIC CURRENTS. 489

the properties of the liquids must have an important in-
fluence upon osmose, both from differences in the attrac-
tion of the membrane for the liquids, and their different
degrees of diffusibility. In order to appreciate fully all the
physical phenomena of osmose, it will be necessary to study
carefully the laws of diffusion of liquids and the diffusibility
of different solutions ; but it will be sufficient for our present
purpose to state a few general propositions, which will be
fotind more or less applicable to physiological absorption.

When two liquids, capable of mixing with each other,
are brought together, they diffuse with greater or less rapid-
ity, until the constitution of the mixture becomes uniform.

Different liquids possess widely different degrees of diffu-
sibility ; and as a rule, in saline solutions, the rate of dif-
fusion increases in proportion to the strength of the solution,
at least when the quantity of salt dissolved does not exceed
four or five per cent.1 It follows from this that the activity
of the endosmotic current toward any saline solution will be
greatest at the beginning of the experiment, and will pro-
gressively diminish as the currents continue and the two
liquids assume a more nearly uniform density.

The rate of diffusion of different solutions is generally
increased by a moderate elevation of temperature.

Bearing in mind these general laws, and remembering
that they are applicable to diffusion as it takes place through
animal membranes, we can easily understand how different
liquids and solutions, in an endosmometer, will attract with
different degrees of intensity any given liquid, such as pure
water ; and how this attractive force, which is measured by
the rapidity and extent of the rise of liquid in the endosmom-.

1 GRAHAM, Elements of Inorganic Chemistry, Philadelphia, 1858, p. 743.

The diffusibility of different acid and saline solutions has been very fully in-
vestigated by Graham, who has developed many interesting facts showing the
influence of different liquids upon osmotic phenomena. For further information
on this subject, the reader is referred to the papers published by Graham in the
Philosophical Transactions, in 1849, 1850, and 1857 ; and to the chapter on "Dif-
fusion of Liquids," in the Elements of Inorganic Chemistry, by the same author.

490 ABSORPTION.

eter, may be modified by the concentration of the solution,
differences in temperature, and other, conditions. The in-
fluence which the membrane exerts upon the relative inten-
sity of these currents is dependent to a certain extent upon
the diffusion which takes place when the two liquids come
together in its substance.

As a rule to which there are not very many exceptions,
pure water will penetrate animal membranes more readily
than any other liquid ; and it is consequently from the water
to the liquid contained in the endosmometer that the principal
current generally takes place. Liquids like alcohol, saline so-
lutions, etc., which have this property, are said to be positively
osmotic ; while those with which the current takes place in
the opposite direction, such as oxalic acid, weak hydrochloric
acid, bichloride of platinum, etc., are said to be negatively
osmotic. In a series of experiments with different liquids,
if the endosmometer be always the same, and all the liquids
used be exposed to the action of pure water, in a given time
a definite change in the quantity of fluid in the endosmom-
eter will be produced, which will be indicated by a certain
amount of elevation or depression in its level.

Endosmotic Equivalents. — The term endosmotic equiva-
lent is often used in comparing the endosmotic power of
different solutions. The degrees by which these equivalents
are represented are entirely arbitrary, and are intended to
represent the force with which various solutions attract pure
water. Among those who have experimented upon this sub-
ject, Graham has, perhaps, made the greatest number of com-
parative observations. He has avoided some of the sources
of error which were not provided against by Dutrochet, and
has always been careful to operate with different solutions
under conditions as nearly identical as possible. "We can
give the best definition of endosmotic equivalents by describ-
ing in detail the manner in which the experiments of Gra-
ham were performed.

ENDOSMOTIC EQUIVALENTS.

491

Fig. a

The apparatus used was an endosmometer, made on the
same principle as the instrument constructed by Dutrochet,
but so modified as to obviate certain elements of inaccuracy
in comparative experiments. The reservoir, or bulb, was three
inches in diameter at the lowest portion, to which the mem-
brane was applied, and its capacity was five or six ounces.
To this was attached a vertical tube, six inches in length,
with a calibre of about
three-tenths of an inch,
or one-tenth the diameter
of the bulb. The mem-
brane used was the blad-
der of the ox, with the
muscular coat removed.
Sometimes the membrane
was doubled. To avoid
the stretching of the mem-
brane by pressure of li-
quid in the tube, it was
supported by a slightly
concave perforated zinc
plate, carefully varnished,
to prevent its being acted
upon by the solutions, and
resting on a tripod. This
apparatus was filled with
the solution up to a point
marked zero on the verti-
cal tube, and then placed
in a jar containing about
sixtv ounces of distilled

, „ n ^ . -, Instrument used by Graham for determining os-

Water, tile SUriaCe OI Which motic equivalents. (Elements of Inorganic
_ ,, , , Chemistry, Philadelphia, 1858, p. 749.)

was careiully brought to

the level of the liquid in the tube.1 In most of the com-

GRAHAM, On Osmotic Force. — Philosophical Transactions, London, 1854, p.

185.

492 ABSOKPTKXN".

parative observations, the same membrane was used, being
soaked for a number of hours in distilled water before each
experiment. The tube was graduated in millimeters, and in
each observation, the degrees of elevation or depression were
noted hourly for five hours. "When the principal current was
from the exterior to the interior, the liquid in the endos-
mometer was said to be positively osmotic, and the number
of degrees of elevation in the tube after immersion for five
hours was taken as its osmotic equivalent. When, on the
other hand, there was an excess in the diffusion of the li-
quid, it was said to be negatively osmotic, and the number
of degrees of depression in the tube after immersion for five
hours was taken as its negative osmotic equivalent.

"With this apparatus, Graham determined the osmotic
equivalents of a number of different solutions, the strength
of each being one per cent. In the following table are given
a few of these results :

Osmose of one per cent. Solutions in Membranes.1

Oxalic acid — 148

Hydrochloric acid (O'l per cent.) — 92

Bichloride of tin — 46

Chloride of sodium + 2

Chloride of potassium + 18

Chloride of calcium + 20

Sulphate of magnesia. + 14

Protochloride of iron + 435

Chloride of mercury +121

Mercuric nitrate + 476

Chloride of aluminium + 540

Carbonate of potash + 439

Experiments on the endosmotic power of different liquids
have been very numerous, and some of them, particularly
those referring to the endosmotic power of albumen, possess
considerable physiological interest. The great endosmotic
power of albumen, or the force with which albumen attracts

1 GRAHAM, Op. cit. — Philosophical Transactions, London, 1854, p. 225, and
Elements of Inorganic Chemistry, Philadelphia, 1858, p. 750.

ENDOSMOTTC EQUIVALENTS. 493

liquids and causes them to pass through membranes, was
early pointed out by Dutrochet;1 and the experiments of
Mialhe, to which we have already referred, have developed
the interesting fact, that while albumen attracts liquids
powerfully, it is not exosmotic.2 The important applica-
tions of this fact to vascular absorption are evident.

Some of the modifications in the endosmotic currents,
due apparently to very slight changes in the constitution of
the liquids, show an influence exerted by these conditions
which undoubtedly is capable of important applications to
physiological absorption ; but unfortunately, the ascertained
facts bearing upon the subject are few and imperfectly un-
derstood. Dutrochet observed that the presence of a very
small quantity of hydrosulphuric acid in a solution of gum
or of sugar diminished very considerably the endosmotic
action, by giving rise to a powerful exosmotic current from
the acid to the water.3 A still more remarkable fact was
observed by Poiseuille. This observer filled an endosmom-
eter with a solution of chloride of potassium, immersed
it in serum, and noted quite a rapid elevation of the liquid
to the height of nine millimeters; but on substituting for
this a solution of the same density, to which the hydro-
chlorate of morphia had been added in the proportion of a
little more than one per cent., the liquid rose only to the
height of six millimeters, and there then followed a decided
exosmotic current.4

As we have seen that there are various conditions capable
of profoundly modifying physiological absorption, it will be
interesting and useful to compare them with the physical
and other conditions which influence endosmosis. In this
way we will be enabled to appreciate more fully the appli-

1 DDTROCHET, De VEndosmose. — Memoires, Paris, 1837, p. 46.

3 See page 477.

8 DUTROCHET, op. cit., p. 64.

4 POISEUILLE, Rechcrches Experimentales sur les Medicaments.— Comptes
Rendus, Paris, 1844, tome xix., p. 1000.

494: ABSORPTION.

cations of physical laws to the phenomena of absorption as it
occurs in the living body.

Modifications of Endosmosis.

Modifications due to the Extent and Thinness of the Per-
meable Membrane. — It has been found in endosmotic experi-
ments, that the activity of the currents is in proportion to the
extent of the endosmotic surface and the thinness of the per-
meable membrane. In physiological absorption, the most
favorable conditions for endosmosis are realized in the capil-
lary system of highly vascular parts. The extent of absorb-
ing surface is here enormous ; and the walls of the vessels are
exceedingly delicate and permeable. The experiments of
Hagendie and others on vascular absorption, which have al-
ready been considered in detail, demonstrate the great ra-
pidity with which soluble substances are absorbed from the
highly vascular mucous membrane of the intestinal canal ;
and the experiments upon absorption through the walls of
the jugular vein show how much more slowly this takes place
when the membrane is thick, and the surface comparatively
restricted.1

Modifications due to Pressure and the Density of
Liquids. — The force of the endosmotic current is frequently
so great as to overcome a very considerable pressure. This
is illustrated in all experiments in which the liquid in an
endosmometer is made to rise in a long tube. If a closed
membranous sac containing a highly endosmotic liquid be
immersed in water, the force with which the liquid pene-
trates will often be sufficient to rupture the membrane itself;
as is shown when an egg, with a part of its shell removed, is
placed in water. This forcible character of the endosmotic
current early attracted the attention of Dutrochet, whose
experiments on this point were very interesting. He intro-
duced into the reservoir of an endosmometer a saccharine
1 See page 472.

MODIFICATIONS OF END03MO3IS. 495

solution of 1*035 density, charging his tube, which was bent
in the form of a V, with a column of mercury one inch in
height. At the end of twenty-eight hours, the ascent of the
column of mercury was arrested at ten inches and seven
lines. Using a saccharine solution of 1*070 density, and
charging the tube with ten inches of mercury, in thirty-six
hours, the elevation of the mercury had become arrested at
twenty-two inches and ten lines. In a third experiment, the
density of the saccharine solution was 1*040, and the tube was
charged with twenty-two inches of mercury. The experi-
ment lasted for three days, and the elevation of the mercury
was forty-five inches and nine lines. All these experiments
were made at the same temperature (69° Fahr.)1

These experiments, which have frequently been repeat-
ed in a more or less modified form, illustrate three points :
first, the great force of the endosmotic current ; second, the
fact that this current may be arrested by a sufficient amount
of pressure ; for in the second experiment, after endosmosis
had ceased and the mercury had been elevated nearly
twenty-three inches, the density of the liquid in the endos-
mometer had been reduced from 1*070 to 1*053, when, with-
out pressure, the current would undoubtedly have continued ;
and finally, these experiments illustrate the fact that, within
certain limits, the force of the endosmotic current is in pro-
portion to the concentration of the solution in the endos-
mometer.

Even in the large arteries, the pressure of blood seldom
exceeds six inches of mercury, and it is much reduced
when the blood passes into the capacious system of capillary
vessels and thence into the veins. This amount of pressure,
then, though capable of exerting a marked influence upon
the rapidity of absorption, would not materially oppose the
introduction of liquids of low density^ even were its effects
not counteracted to a certain extent by other circumstances *
for it must be remembered that the blood has a specific

1 DUTROCHET, op. cit, tome i., p. 38.

496 ABSORPTION.

gravity of from 1*050 to 1*060, and contains salts and albu-
men, substances possessing highly endosmotic properties.
. Circulation of the blood is the most important condition
modifying the opposing influence of pressure. This condi-
tion is so important in modifying endosmosis that it de-
mands special consideration. It is sufficient in this connec-
tion, however, to appreciate the fact of its powerful influence
in promoting the endosmotic current.

Variations in the pressure in the blood-vessels has already
been alluded to as exerting an important influence on the
rapidity of absorption. When the entire quantity of blood
is diminished by hemorrhage or prolonged abstinence, the
.activity of endosmosis is immensely increased ; and it is cor-
respondingly diminished when the pressure is increased, as in
plethora or after injection of fluids into the blood-vessels of
a living animal. This rule does not apply to those instances
of local increase in the pressure of blood which are attended
with very great increase in the activity of the circulation, as
in the mucous membrane of the intestinal canal during diges-
tion and absorption.

In physical experiments, all observers have noticed a great
increase in the activity of the currents with an increase in
the density of the endosmotic solution. Graham found that
with a solution containing two per cent, of sulphate of mag-
nesia, the minimum of elevation in the tube of the endos-
mometer was 30, and the maximum 33 millimeters ; with so-
lutions containing five per cent, of the salt, the minimum
was 73, and the maximum 76 ; with solutions containing ten
per cent., the minimum was 134, and the maximum 152 ; and
with solutions containing twenty per cent., the minimum was
238, and the maximum 283.1

These facts are directly applicable to the blood and the
influence of the concentration of this fluid upon absorption.

1 GRAHAM, op. cit. — Philosophical Transactions, London, 1854, p. 199. These
figures are selected from a large number of observations upon different saline so-
lutions, all of which were followed by essentially the same results.

MODIFICATIONS OF ENDOSMOSIS. 497

i

In physiological absorption, the salts of the blood exert a
certain amount of endosmotic force, but of all its constitu-
ents, albumen is the most efficient in this regard. The
greater the relative proportion of albumen to the watery con-
stituents, the greater will be the activity of endosmosis. It
is in this way that the hydragogue cathartics, by largely di-
minishing the watery constituents of the blood, at the same
time that they diminish the pressure, increase the activity of
absorption. The albumen of the blood also opposes exosmo-
sis, or transudation ; and when its proportion is considerably
diminished, dropsies into the areolar tissue and the serous
cavities are apt to occur.

Modifications due to Movements of the Liquids. — Move-
ments of the liquids, in endosmotic experiments, are capable
of increasing the activity of the currents in two ways. In
the first place, by agitating the liquids the rapidity of diffu-
sion is increased and fresh layers of liquid are brought in
contact with the membrane. It is well known to all that
have experimented on this subject, that in an ordinary en-
dosmometer, after the current has become very feeble or has
entirely ceased, it may be again excited by simply agitating
the liquids. This fact was accurately described and explained
by Poiseuille. He placed an endosmometer filled with a
solution containing four per cent, of phosphate of soda in a
vessel of serum. The liquid mounted in the tube to the
height of thirty-four millimeters, but after some hours .of
complete repose, it descended to about three millimeters
above the level of the external liquid. On slightly agitating
the apparatus, the ascent recommenced at the rate of four
millimeters per hour.1 Poiseuille explains this fact on the
principle that endosmosis and exosmosis had gone on in that
portion of the liquid near the membrane until the density of
the saline solution had been reduced to a point at which the

1 POISEUILLE, Reclierches Experimentales sur les Medicaments. — Comptca
Rendus, Paris, 1844, tome xix., p. 997.
82

498 ABSOBPTION.

current takes place in the opposite direction ; as he had pre-
viously demonstrated that with one per cent, solutions of
phosphate of soda, the current was always from the saline
solution to the serum. This great diminution in density,
however, he assumed to be only local ; and the endosmotic
current recommenced when general diffusion was hastened
by agitation of the liquids. In experiments such as those
performed by Matteucci and Cima, in which fluid is made
to pass in a current through a portion of a vein which is
immersed in a vessel of acidulated water, the rapid pene-
tration of the acid is due in part to the suction force pro-
duced by the current, and in part to the constant renewal of
liquid on one side of the membrane. In an experiment of
this kind, Matteucci found that an acid reaction was almost
immediately manifested in the liquid flowing from the vein
when a current was established, but the penetration required
some time when the liquids were motionless.1

In the vascular system, all the conditions are realized for
the greatest development of the influence exerted upon en-
dosmosis by the movements of liquids. The blood is circu-
lating in the small vessels under a pressure much less than
that in the general arterial system. It contains a large pro-
portion of albumen, the fluid of all others which powerfully
attracts an endosmotic current without itself passing through
membranes. The circulation is so rapid that what enters
through the walls of the vessels is immediately carried on to
the heart, and in less than thirty seconds (the estimated du-
ration of the entire circuit of the blood), by the churning
action of this organ as well as the diffusion produced by the
force of the current, is mixed with the whole mass of the
circulating fluid. The substance absorbed must then mod-
ify the whole mass of blood (which is estimated at eighteen
pounds, in a man of ordinary size) before the activity of ab-
sorption can be diminished by an alteration in the density of

1 MATTEUCCI, Lemons sur les Phenonenes Physiques des Corps Vivants, Paris,
1847, p. 78.

MODIFICATIONS OF ENDOSMOSIS. 499

tlie fluid toward which the current is directed. In ordinary
absorption, this modification must be so slight as to have no
material influence upon the endosmotic action.

Modifications due to Variations in Temperature. — The
original experiments of Dutrochet developed some striking
physical facts with regard to the influence of temperature on
the endosmotic current, which have been repeatedly confirmed
by later observers. In experiments with the caecum of a
fowl, filled with a solution containing one part of gum to ten
of water, he found that the apparatus immersed in water at 41°
Fahr. for an hour and a half gained thirteen grains in weight ;
while it gained twenty-three grains in the same time when
the temperature of the water was raised to from 88° to 90°,
notwithstanding the fact that the liquid had already become
somewhat less endosmotic by the introduction of water in
the first experiment.1

Under ordinary conditions, physiological absorption is
not much influenced by temperature, for most of the liquids
to be absorbed are soon brought to the general temperature
of the body; but it is a general observation that warm
liquids are absorbed more rapidly than cold.

Modifications induced lyy Electricity. — In a physical
point of view, the influence of electricity upon the endos-
motic current is very interesting ; and it is impossible to say
that this force does not intervene in the phenomena of absorp-
tion in the living body. JSTevertheless, there are no sufficient
data for assuming that physiological absorption has any thing
to do with electricity ; and it is much more reasonable to sup-
pose that the modifications in absorption which are effected
through the nervous system are due to the influence of the
nerves upon the circulation.2 In view of the early experi-
ments of Porrett, who produced an endosmotic current

1 DUTROCHET, Memoires, etc., tome i., p. 27.
8 See page 468.

500 ABSORPTION.

through an animal membrane with pure water on either side,
by simply immersing in the fluids the poles of a galvanic
battery,1 and the experiments of Dutrochet, who produced
currents in the same way through the caecum of the fowl,2
the idea was advanced that all endosmosis was dependent
upon galvanic action. !N"o one, however, has ever professed
to have detected a galvanic current during ordinary endos-
mosis, by the galvanometers usually employed, and this the-
ory is without any positive basis.

These observations of Porrett and Dutrochet have been
repeatedly verified by later experimenters. They showed a
tendency to diffusion in two portions of the same liquid,
separated by a membrane, when one was charged with posi-
tive and the other with negative electricity, the current tak-
ing place from the positive to the negative pole. Under
these circumstances, the endosmotic current is actually pro-
duced by galvanic action, for it never takes place when the
liquids on either side of the membrane are identical. Other
experiments, which it is unnecessary to refer to in detail,
have shown that the phenomena of osmosis between liquids
of different constitution may be modified by galvanic action,
that the currents may be established in this way where they
would not otherwise take place, and that existing currents
may be arrested or even reversed. The experiments of
Fodera (which were made upon living animals before the
description of endosmosis by Dutrochet), are striking exam-
ples of the influence of electricity upon the passage of solu-
tions through animal membranes. This observer found that
while it required from half an hour to an hour and a half for
a solution of sulphate of iron and a solution of prussiate of pot-
ash, placed upon either side of an animal membrane, to pene-
trate its substance and produce the characteristic blue reac-
tion, when the liquids were connected with the poles of a gal-

1 PORRETT, Curious Galvanic Experiments. — Annals of Philosophy, London,
1816, vol. viii., p. 74.

2 Op. tit, p. 71.

APPLICATION OF PHYSICAL LAWS TO ABSORPTION. 501

vanic battery, this result was produced " in a few minutes and
even in a few seconds, according to the power of the pile and
the energy of its action." This is only one of a number of ex-
periments by Fodera illustrating the influence of the galvanic
current upon imbibition and absorption.1

The only definite applications of these facts to physiology
have been made in connection with the influences of the
nervous system upon absorption; and this has been done
under the idea that there is something in common between
the nervous force and electricity. If we are to determine the
existence of electrical action by the usual methods, the gal-
vanic current cannot be regarded as identical with nervous
power. The only way which we have of detecting a gal-
vanic current is by instruments known as galvanometers;
and those used at the present day in accurate investigations
are exceedingly sensitive. "With the most delicate instru-
ments known, it is impossible to detect any galvanic current
during endosmosis, or during the conduction by nerves of
the so-called nervous force. There is no reason, therefore, to
suppose that absorption is affected by galvanic action operat-
ing through the nervous system, and we must be content
with the explanations of nervous influence already given.3
Nevertheless, galvanic currents have been detected between
different tissues and different parts of the same tissue during
life and immediately after death; but we have not as yet
been able to determine positively the influence of these cur-
rents upon any of the important functions.

Applications of Physical Laws to the Function of
Absorption.

In no experiments performed out of the body, can the
conditions favorable to the passage of liquids through mem-
branes in accordance with purely physical laws be realized as

1 FODERA, Recherches Experimental es 'sur V Absorption et Exhalation, Paris,
1824, p. 22.

2 See page 468.

502 ABSORPTION.

they exist in the living organism. The vast extent of the
absorbing surfaces ; the great delicacy and permeability of
the membranes ; the rapidity with which principles are car-
ried on by the torrent of the circulation, as soon as they pass
through these membranes ; the uniformity of the pressure,
notwithstanding the penetration of liquids; all these favor
the physical phenomena of absorption in a way which can-
not be imitated in artificially constructed apparatus. It
is not necessary to invoke the vital properties of tissues to
explain the ordinary phenomena of absorption. Enough has
been learned of the laws which regulated endosmosis and
exosmosis to enable us to explain most of these phenomena
upon physical principles. This fact has been apparent in
studying these principles in their relation to absorption in
the living body- But it is an important question to deter-
mine whether this be applicable to all the varied phenomena
of physiological absorption. In other words, are there any
modifications in this function which cannot, as yet, be ex-
plained by physical laws ?

Admitting the fact that the general process of absorption
takes place in accordance with the laws of endosmosis, we
will now consider some of the phenomena which appear to
be in opposition to known physical principles, or in which
the application of these principles seems to be imperfectly
understood.

It is not easy to understand how particles of emulsified
fat find their way through the walls of the lacteals and the
blood-vessels. The experiments of Matteucci with alkaline
emulsions, which we referred to fully in connection with the
absorption of fats, seem to show that alkalinity is a condition
necessary to the penetration of fatty particles, though they do
not offer an explanation of the mechanism by which these
particles pass through membranes. It has been demonstrated
that the epithelium which covers these membranes becomes
filled with fatty granules during the absorption of emulsions,
and we must invoke the aid of " cell-action," — concerning

APPLICATION OF PHYSICAL LAWS TO ABSORPTION. 503

which it must be confessed that there exists very little defi-
nite information — in explanation of this phenomenon. The
penetration of membranes by fatty particles must be re-
garded as one of the points which cannot be fully explained
by the laws of endosmosis.

There are certain experiments on absorption, in the living
body, to which a great deal of importance was attached by
Longet, which are seemingly in opposition to physical laws.
This author states that when solutions of sugar of different
densities are secured in isolated portions of the intestine of a
living animal, the denser solutions are absorbed with as
much rapidity as those which are less concentrated. He also
shows that saline solutions of greater density than the blood
are absorbed in the living animal, when, according to physi-
cal laws, the current should take »place in the opposite
direction.1 The view that these facts are in opposition to
physical laws is very successfully controverted by Milne-
Edwards. This author, referring to some experiments by
Von Becker in support of his position, asserts that there is
first an exosmosis of the watery portions of the blood to these
dense solutions, with a feeble penetration of the solutions into
the blood-vessels, until, by the laws of diffusion, the solutions
become so diluted as to be taken into the circulation.2 Such
an action as this could not take place between two saline solu-
tions in an endosmometer, for both currents would cease when
the liquids became of equal density ; but it has been shown
that after endosmosis in an endosmometer has ceased, it may
be again induced by simply agitating the liquids. In phys-
iological absorption, the motion is constant and very rapid,
and solutions in their passage along the alimentary canal are
continually exposed to fresh absorbing surfaces. Further-
more, the albumen of the blood, which is very slightly ex-
osmotic, will attract an endosmotic current from liquids
even when they are of the same density. The kind of ac-

1 See page 464.

3 MILNE-EDWARDS, Lemons sur la Physiologic, Paris, 1859, tome v., p. 192.

504 ABSORPTION.

tion described by Milne-Edwards would be by no means an
isolated example of a liquid passing out of the blood-vessels
to be again absorbed after it has acted upon matters contained
in the alimentary canal. This takes place with all the di-
gestive fluids ; and the liquid is effused, not by simple exos-
mosis, but by an act of secretion excited by the impression
made upon the mucous membrane. We are not justified,
therefore, in assuming, with Longet, that the absorption of
solutions of greater density than the blood is always in op-
position to the laws of end osmosis.

The imbibition of the coloring matter of the bile by the
coats of the gall-bladder after death, while nothing of the
kind takes place during life, is not due to the absence of vital
action. During life, the circulation in the mucous membrane
of this reservoir would readily remove the few particles of
coloring matter which might penetrate from the bile, and of
course there is no time for any coloration to take place.

In treating of the variations and modifications of absorp-
tion, we noted an apparent elective power in the mucous
membrane of some portions of the alimentary canal. This
is illustrated in the failure of the mucous membrane to ab-
sorb the woorara and various of the animal poisons, which,
as a rule, are only effective when introduced into a wound or
injected into the areolar tissue. The separation of various
soluble substances by the process known as dialysis may
throw some light upon this subject, but as yet we have no
facts which offer a satisfactory explanation of this phenome-
non.1 Certain of these phenomena which show an apparent
elective power in absorbing membranes are probably due to
a cell-action resembling secretion ; for all these surfaces are
covered with epithelium, which must be penetrated before
the fluids can get to the blood-vessels. But even with regard
to the selection of materials from the blood to form secre-
tions, very little of a definite character is known.

Those who believe that absorption is often modified by
1 See page 477, note.

TEANSUDATION. 505

vital action offer this in explanation of the important influ-
ence of the nervous system on this function. Precisely how
the nervous system affects absorption, in all instances, it is
impossible in the present state of our knowledge to deter-
mine ; but modifications are frequently effected through the
sympathetic system. These nerves, as is well known, are
capable of producing important local changes in the circula-
tion, and can even temporarily arrest the capillary circula-
tion in some parts ; and it is in this way that many of the
variations in absorption may be produced.

Transudation. — Although the endosmotic is the princi-
pal current in the functions which have thus far been consid-
ered, this is always accompanied by a certain amount of
exosmosis. All the soft and vascular tissues, and all the cav-
ities and tubes, contain a certain amount of exhaled or transu-
ded fluid. This may be small in quantity and hardly more than
vaporous, as it is over the pleura or peritoneum, or it may be
liquid and in a decidedly appreciable quantity, like the inter-
muscular fluid, etc.; but all these vascular tissues are moist-
ened by liquid which has transuded the permeable walls of the
blood-vessels. The subject of transudation, however, is so
closely connected with secretion, that its full consideration
will come properly under that head, in another volume. At
present it will be sufficient to notice only a few facts which
relate to this subject. There is probably a feeble exosmot-
ic current in the alimentary canal ; which will account for
the presence of certain salts, etc., in the faeces, which are
evidently derived from the blood. In the subcutaneous
areolar tissue and in the substance of and between the mus-
cles, there is a certain quantity of a liquid containing a very
minute proportion of albumen and some inorganic salts.
This is transuded from the blood-vessels by so simple a pro-
cess that it hardly merits the name of secretion.

Transudation of these liquids is influenced chiefly by the
pressure of blood in the vessels and by the constitution of

506 ABSORPTION.

the circulating fluid. The influence of pressure, which is so
often observed in the dropsies which result from venous ob-
struction, was noted nearly two hundred years ago by Lower,
who observed that there was a serous effusion under the
skin of the face of a dog after the jugular veins had been
tied.1 This fact is too well established to need further illus-
tration.

The influence of the constitution of the blood upon transu-
dation is very interesting. The exosmotic properties of albu-
men are so slight, that there is usually but a very small amount
of transudation through any of the vessels, and the fluid thus
effused contains but a minute quantity of albumen ; but if the
density of the blood be greatly diminished, and especially if it
become impoverished in albumen, transudation may become
so active as to produce general dropsy. The deficiency
in albumen in the blood of persons suffering from general
dropsy was observed by Bostock, who, at the instance of Dr.
Bright, made a number of examinations of the blood from
patients suffering from what is now known as renal dropsy.
" In the serum of these patients the proportion of albumen
was found to be less than in health." 2 This fact has since
been noted by other observers, particularly by Becquerel
and Kodier, who made a large number of observations show-
ing the influence of a deficiency of albumen in the blood
upon transudation.3 These facts have a pathological rather
than a physiological bearing, but they illustrate the influence
of the albumen of the blood upon normal transudation by
exosmosis.

1 LOWER, Tradatus de Corde, item de Motu et Colore Sanguinis, ct Cliyli in
eum Transitu, Amstalodami, 1669, p. 124.

8 BOSTOCK, An Elementary System of Physiology, London, 182*7, p. 411.

3 BECQUEREL ET RODIER, De TAnemis par Diminution de Proportion de VAl-
bumine du Sang, et des Hydropsies qui en sont la Consequence. — Extrait de la Ga-
zette Medicate de Paris, 1850.

CHAPTEE XYII.

LYMPH AND CHYLE.

Mode of obtaining lymph — Quantity of lymph — Properties and composition of
lymph— Alterations of the lymph — Influence of starvation upon the lymph —
Corpuscular elements of the lymph — Leucocytes — Development of leucocytes
in the lymph and chyle — Globulins — Origin and function of the lymph-
Chyle — General properties of the chyle — Composition of the chyle— Compar-
ative analyses of the lymph and the chyle — Microscopical characters of the
chyle — Movement of the lymph and the chyle — Pressure of fluids in the
lymphatic system — General rapidity of the lymphatic circulation — Causes of
the movement of the lymph and chyle — Influence of the forces of endosmosis
and transudation — Influence of the contractile walls of the vessels — Influ-
ence of pressure from surrounding parts — Influence of the movements of
respiration.

To complete the history of physiological absorption, it
will be necessary to study carefully the origin, composi-
tion, and properties of the lymph and chyle. It is only
within a few years that physiologists have been able to ap-
preciate the importance of the lymph, for the experiments
indicating the enormous quantity of this liquid which is con-
tinually passing into the blood are of recent date. The
earlier experimenters never succeeded in obtaining more than
a small quantity of fluid from the lymphatic system. On
the other hand, for the long period during which it was sup-
posed that all the products of digestion entered the system by
the thoracic duct, the importance of the chyle was much exag-
gerated ; but the researches upon intestinal absorption by
Magendie and those who followed him, and the experiments
of Colin on the quantity of fluid which passes into the blood
by the thoracic duct during the intervals of digestion, have

508 ABSOEPTION.

enabled physiologists to form a better estimate of tlie im-
portance of the lymph and chyle. In studying the proper-
ties of these fluids, the consideration of the lymph naturally
precedes that of the chyle ; as the latter consists simply of
lymph, to which certain of the products of digestion have
been added during absorption from the alimentary canal.

Lymph.

Mode of obtaining Lymph. — The old methods of obtaining
this fluid are no longer employed. In the inferior animals,
recently killed, a few drops may be obtained by pricking the
lymphatic glands, or by exposing the right lymphatic trunk
or the thoracic duct, and collecting the small quantity of fluid
which is discharged when these vessels are punctured. Al-
though a notable quantity of chyle can be obtained from the
thoracic duct of an animal killed during intestinal absorption,
it is difficult to collect even a small quantity of fluid during
the intervals of digestion. Yarious occasions have presented
themselves for obtaining lymph, possessing more or less of its
normal characters, from the human subject during life ; but
in many of these instances, as in the observations of Wutzer,
Sommerring^l^asse, Marchand and Colberg, and some others,
there existed some pathological condition of the lymphatic
system, and it cannot be assumed that the liquid thus ob-
tained was in a perfectly healthy condition.

The first successful experiments in which the lymph and
chyle were obtained in quantity were made by Colin. This
observer, in operating upon large animals, particularly the
ruminants, experienced no great difficulty in isolating the
thoracic duct near its junction with the subclavian vein, and
introducing a metallic tube of sufficient size to allow the free
discharge of fluid.1 These experiments, made upon horses

1 COLIN, Traite de Physiologie Comparee des Animaux Domestiques, Paris,
1856, tome ii., p. 100.

The idea of establishing a fistula into the thoracic duct did not originate with
Colin, although he was the first to perform the experiment successfully. In the

LYMPH. 509

and the larger ruminants, were the first to give any clear
idea of the quantity of liquids— lymph and chyle — which
pass through the thoracic duct. In an observation upon a
cow of medium size, he succeeded in collecting, in the course
of twelve hours, the enormous quantity of 105 '3 Ibs. av,
(47,963 grammes) ; and he further states that a very much
greater amount can be obtained by operating upon rumi-
nants of larger size.1 Whether this represents the actual
quantity which is normally discharged into the venous cir-
culation is a question which will be considered under the
head of the probable quantity of lymph and chyle ; but it
certainly shows that the lymph cannot but be regarded as
one of the most important of the animal fluids.

Among the observations upon the fluids discharged from
the thoracic duct which followed the experiments of Colin,
the most interesting are those made in 1859, by Daltoii,
who operated upon carnivorous as well as herbivorous ani-
mals. These experiments were performed upon young goats
and dogs ; and the general results with regard to the quan-
tity of fluids discharged closely corresponded with those ob-
tained by Colin.2 The operation of making the fistula in
goats is not very difficult, all that is necessary being to cut
down upon the subclavian vein at the point where the duct

latter part of the last century, Flandrin, who made a number of experiments upon
the effects of ligating the thoracic duct in horses (see page 449), attempted to
make a fistula into the canal by exposing it and introducing a tube made of
tin. He did not succeed, however, in obtaining the chyle in quantity, as the
tube soon became obstructed. (FLAXDRIN, Suite des Experiences sur V Absorption
des Vaisseaux Lymphatiques dans les Animaux. — Journal de Medecine, Chirurgie,
Pharmacie, etc., Paris, 1791, tome Ixxxvii., p. 230 et seq.)

1 COLIN, op. cit, tome ii., p. 106.

2 DALTON, The Physiology of the Circulation. — A Course of Lectures delivered
in the College of Physicians and Surgeons, New York, in the Fall Term of 1859. —
American Medical Monthly and New York Review, December, 1860, p. 415 ; and
Treatise on Human Physiology, Philadelphia, 1864, p. 322.

Dr. Dalton, in his experiments upon dogs, poisoned the animals with woorara,
and collected the liquid which flowed from the thoracic duct, the circulation being
kept up by artificial respiration.

510 ABSORPTION.

empties into it, and fix in it a tube of appropriate size ; but
in dogs, the vessels are more deeply situated, and the opera-
tive procedure is much more tedious. This, however, is the
only way in which lymph and chyle can be obtained from
the lower animals in any considerable quantity.

Quantity of Lymph. — Although the experiments just
described might at first seem sufficient to give a pretty
clear idea of the entire quantity of lymph discharged into
the venous system, it is evident that the conditions of the
circulation of this fluid must be so seriously modified by the
establishment of a fistula, that the results thus obtained are
far from being entirely satisfactory. In the first place, Colin
found that the canal, at its junction with the subclavian
vein, was seldom single ; and in many of his observations in
which a very large quantity of liquid was obtained, there were
several vessels of nearly equal size emptying into the venous
system. In the experiment which we have referred to, how-
ever, the opening was single; and the quantity of fluid
obtained represented all that passed up the thoracic duct
during the time that the observation was continued. As
we should naturally expect, the discharge of liquid was
subject to certain variations, its maximum corresponding
with the period of greatest activity in digestion and ab-
sorption.

It is not possible to estimate the influence of the unob-
structed discharge of lymph and chyle by a fistulous opening
upon the absolute quantity which passes out of the canal ;
and in the natural course of the circulation, there is a certain
amount of obstruction to ics entrance into the vein, which
might sensibly retard the current.

According to the estimates of Dalton, deduced from his
own observations upon dogs and the experiments of Colin
upon horses, the total quantity of lymph and chyle produced
in the twenty-four hours in a man weighing one hundred
and forty pounds is from six to six and a half pounds. And,

QTJAOTTTY OF LYMPH. 511

again, reasoning from experiments made upon dogs eighteen
hours after feeding, when the fluid which passes up the tho-
racic duct may be assumed to be pure unmixed lymph, the
total quantity of lymph alone, produced in the twenty-four
hours by a man of ordinary weight, would be between three
and a half and four pounds (3-864: Ib.).1 These estimates can
only be accepted as approximative ; and they do not indicate
the entire quantity of lymph actually contained in the or-
ganism.

There are no very late researches with regard to the va-
riations in the quantity of lymph. Collard de Martigny
made a series of elaborate investigations a number of years
ago, with regard to the effects of starvation upon the consti-
tution and the quantity of the lymph. He found the lym-
phatics always distended with fluid in dogs killed after two
days of total deprivation of food. This condition continued
during the first week of starvation ; but after that time, the
quantity in the vessels gradually diminished, and a few hours
before death, the lymphatics and the thora,cic duct were nearly
empty. In comparing the quantity of fluid in the lymphat-
ics of the neck during digestion and absorption, with the
quantity which they contained soon after digestion was com-
pleted, the same observer found that while digestion and
absorption were going on actively, the vessels of the neck
contained scarcely any fluid ; but the quantity gradually in-
creased after these processes were completed."

Properties and Composition of Lymph. — Lymph taken
from the vessels in various parts of the system, or the fluid
which is discharged from the thoracic duct during the inter-
vals of digestion, is either perfectly transparent and color-

1 DALTON, Treatise on Human Physiology, Philadelphia, 1864, p. 322.

2 COLLARD DE MARTIGNY, Recherches Experimentales sur les Effete de I1 Absti-
nence Complete d'Alimens solides et liquides sur la Composition et la Quantite
du Sang et de la Lymphe. — Journal de Physiologie, Paris, 1828, tome viii., p.
174 et scg.

512 ABSORPTION.

less, or of a slightly yellowish or greenish hue. When al-
lowed to stand for a short time, it becomes slightly tinged
with red ; and frequently it has a faint rose-color when first
discharged. Miscroscopical examination shows that this red-
dish color is dependent upon the presence of a few blood-
corpuscles, which are entangled in the clot as the lymph
coagulates, thus accounting for the deepening of the color
•when the fluid has been allowed to stand. The origin of
these red corpuscles has long been a subject of discussion.
Their constant presence in lymph or chyle discharged by
fistulous openings has led to the opinion that they are normal
constituents of these fluids ; and this view has been adopted
without reserve by those who assume that the blood-corpus-
cles are formed from the white corpuscles, or leucocytes. If
this view of the formation of the corpuscular elements of the
blood be adopted, there is no good reason why red corpuscles
should not be formed from the leucocytes in the lymph and
chyle as well as in the blood itself ; particularly as the clear
fluid of the lymph and chyle contains nearly all the principles
found in the plasma of the blood. On the other hand, many
regard the presence of red corpuscles as always accidental ;
and in support of this view, Robin brings forward the fact
that red corpuscles are never found in lymph taken from a
portion of a vessel included between two ligatures.1 This is
certainly a very strong argument against the constant and
normal existence of red corpuscles in the lymph, particularly
as the connection between the lymphatics and the blood-ves-
sels is very close, and all operations upon the lymphatic sys-
tem involve disturbances in the circulation. There is no
positive evidence of the formation of red corpuscles from the
leucocytes ; and if it be the fact that red corpuscles never
exist in lymph taken from a portion of a lymphatic vessel
included between two ligatures, it is fair to assume that
the presence of these corpuscles in lymph and chyle is

1 ROBIN, Programme du Cours cTHistologie profcsse d la Faeulte de Mede-
dne de Paris, 1862-'63, et 1863-'64, Paris, 1864, p. 112.

PROPERTIES AND COMPOSITION OF LYMPH.. 513

accidental, and that they are always derived from the
blood.

Lymph has no decided or characteristic odor. It is very
slightly saline in taste, — almost insipid. Its specific gravity
is very much inferior to that of the blood. Magendie found
the specific gravity in the dog to be about 1,022.* Kobin
states that the specific gravity of the defibrinated serum of
the lymph is 1,009. 3 In some recent analyses, by Dahnhardt,
of the lymph taken from dilated vessels in the leg. in the
human subject, the specific gravity was only 1,00 7.3 The
exceedingly low specific gravity in the last instance would
rather lead to the opinion that the fluid was not entirely
normal. The difiiculty in obtaining this fluid in a perfectly
normal condition from the human subject has rendered it
impossible to ascertain its normal specific gravity, even ap-
proximatively ; but it evidently possesses a density much
inferior to that of the blood. The reaction of the lymph is
constantly alkaline. According to Robin, the alkalinity
of the lymph is neutralized by 0*37 per cent, of lactic acid,
while the blood is neutralized by 0'50 per cent.4

A few minutes after discharge from the vessels, both the
lymph and chyle undergo spontaneous coagulation. Accord-
ing to Colin, the fluid collected from the thoracic duct in the
large ruminants coagulates at the end of five, ten, or twelve
minutes, and sets into a mass having exactly the form of the
vessel in which it is contained. Colin states that the clot is
tolerably consistent, but that there is never any spontaneous
separation of serum.5 This may be the fact with regard to
the lymph and the chyle of the large ruminants, but in the
observations of Dalton, who operated upon dogs and goats,

1 MAGENDIE, Precis fitimentaire de Physiologie, Paris, 183G, tome ii., p. 192.

2 KOBIN, Programme du Cours, Paris, 1846, p. 111.

8 DAHNHARDT, Zur Chimie der Lymphe. — VIRCHOW'S Archiv, Berlin, 1866,
Bd. xxxvii., S. 59.

4 Loc. cit

6 COLIN, Traite de Physiologic Comparee des Animaux Domesiiques, Paris,
1856, tome ii., p. 111.
33

514: ABSORPTION.

after a few hours' exposure, the clot contracted to about half
its original size, precisely like coagulated blood, and the se-
rum became perfectly separated. In one instance, in the dog,
the volume of serum, after twenty-four hours of repose, was
about twice that of the contracted clot.1 Milne-Edwards, quo-
ting from an unpublished memoir presented by Colin to the
Academy of Sciences, in 1858, states that the lymph does not
coagulate in the vessels, even when the circulation is inter-
rupted.2 This may be the case under ordinary conditions,
when the vessels are simply tied ; but it was found by Flan-(
drin,3 that coagulation obstructed the tubes which he intro-
duced into the thoracic duct so completely that he was able
to obtain but a small quantity of fluid ; a difficulty which is
also mentioned by Colin, who states that " the clearing of
the tube rarely suffices to reestablish the flow, for the coag-
ulum formed in the tube is prolonged for a greater or less
distance into the interior of the thoracic duct." 4 Coagula-
tion of lymph in the vessels during life, if it occur at all,
must be exceedingly infrequent, notwithstanding that the
flow of lymph and chyle is very slow . and irregular, com-
pared with the circulation of the blood, and is subject, prob-
ably, to frequent interruptions.

Although numerous analyses have been made of lymph
from the human subject, the conditions under which the fluid
has been obtained render it probable that in the majority of
instances it was not entirely normal. It will be necessary,
therefore, to compare these analyses with observations made
upon the lymph of the inferior animals ; as in the latter, this
fluid has been collected under conditions which leave no
doubt as to its normal character. In the experiments of

1 D ALTON, Lectures on the Physiology of the Circulation. — The American
Medical Monthly and New York Review, December, 1860, p. 411.

8 MILNE-EDWARDS, Leconssur la Physiologic, Paris, 1859, toine iv., p. 556, note,

3 Loc. cit.

4 COLIN, op. cit., tome ii., page 111.

PROPERTIES AND COMPOSITION OF LYMPH. 515

Coliu especially, the fluids taken from the thoracic duct dur-
ing the intervals of digestion undoubtedly represent the
normal mixed lymph collected from nearly all parts of the
body ; ,and the operative procedure in the large ruminants is
so simple as to produce little if any general disturbance. The
following is an analysis by Lassaigne of specimens of lymph
collected by Colin from the thoracic duct of a cow, under the
most favorable conditions :

Composition of Lymph from a Cow.1

Water! 964-0

Fibrin 0'9

Albumen 28-0

Fatty matter 0'4

Chloride of sodium 5'0

Carbonate, phosphate, and sulphate of soda 1-2

Phosphate of lime 0'5

1,000-0

These proportions are by no means invariable, the differ-
ences in coagulability indicating differences in the propor-
tion of fibrin, and the degree of lactescence showing great
variations in the proportion of fatty matters. The table
may be taken, however, as a pretty close approximation of
•the average composition of the lymph of these animals, dur-
ing the intervals of digestion.

Of the various analyses of human lymph, it will be ne-
cessary only to select a few, as most of them are far from.

1 COLIX, Traite de Physiologie Comparee des Animauz Domestiqties, Paris,
1856, tome ii., p. Ill,

The proportions in this table have been changed from hundreds to thousands.
In this, as in all other analyses of the lymph, the organic constituents are esti-
mated dry. In treating of the composition of the blood (see vol. i., p. 130 et seq.},
we endeavored to show that the water which exists in coagulated fibrin and albu-
men should be considered as water of composition ; coagulation simply altering
the form of these organic principles without changing their constitution. Accord-
ing to this view, an estimate of these substances in a dry state gives the quantity
of the residue after desiccation, and not their actual proportion in a natural
condition.

516 A3SOEPTION.

representing the normal characters of this fluid. Lheritier
analyzed the contents of the thoracic duct of a man who died
of softening of the brain, having taken a little water thirty
hours before death.1 This analysis gives a very large propor-
tion of fibrin, albumen, and fatty matters (3*20 of fibrin, 60*02
of albumen, and*5'10 of fat, per 1,000), so large, indeed, that
some physiologists doubt the accuracy of the results.2 On the
other hand, the analyses of Marchand and Colberg,3 which are
so often quoted, give, as the composition of lymph extracted
from a wound of the lymphatics on the top of the foot, a very
large proportion of water (969*26 parts per 1,000), and conse-
quently a small proportion of solid matter. We would sup-
pose that fluid thus taken from a wounded part must neces-
sarily contain an admixture of pathological secretions.

The analyses of human lymph which seem to be the
most reliable, and in which the fluid was apparently pure and
normal, are those of Grubler and Quevenne. The lymph, in
this case, was collected by Desjardins from a female who
suffered from a varicose dilatation of the lymphatic vessels
in the anterior and superior portion of the left thigh. These
vessels occasionally ruptured, and the lymph could then be
obtained in considerable quantity. When an opening existed,
the discharge of fluid could be arrested at will by flexing the
trunk upon the thigh. Gubler and Quevenne made elaborate
analyses of two different specimens of the fluid, with the fol-
lowing results.4

1 BECQUEREL ET RODIER, Traite de Chimie Pathologique, Paris, 1854, p. 3.

" LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 411.

8 MARCHAND UND COLBERG, Jfeber die chemische Zusammensetzung dcr
menschlicJicn Lymphe. — POGGENDORFF'S Annalen der PhysiJc und Chemie, Leipzig,
1838, Bd. cxix., S. 629.

4 DESJARDINS, Note sur un Cas de Dilatation variqueuse du Reseau Lymplia-
tique superficiel du Derme ; Emission voluntaire de Lymphe ; Analyse de cette
Lymplie,par GUBLER ET QUEVENNE. — Gazette Mcdicale de Paris, 1854, p. 454.

The two tables of Gubler and Quevenne have been brought together and the
proportions changed from hundreds to thousands. An evident error in the sec-
ond analysis (9'92 instead of 0'92 parts of fatty matter per hundred) has been
corrected. For a full account of this case, with the analyses and examinations of

PROPERTIES AND COMPOSITION OF LYMPH. 517

Composition of Human Lymph.

First Analysis. Second Analysis.

Water , 939-87 934-77

Fibrin 0'56 O63

Caseous matter (with earthy phosphates and traces

of iron) 42-75 42-80

Fatty matter (in the second analysis, fusible at

102-3° Fahr.) , 3'82 9'20

Hydro-alcoholic extract (containing sugar, and leav-
ing, after incineration, chloride of sodium, with

the carbonate of soda) 13-00 12-60

1,000-00 1,000-00

The above analyses show a much larger proportion of
solid constituents than was found by Lassaigne in the lymph
of the cow. This excess is pretty uniformly distributed
throughout all the constituents, with the exception of the
fatty matters and fibrin ; the former existing largely in excess
in the human lymph, especially in the second analysis, while
the latter is smaller in quantity than in the lymph of the
cow. It is evident, however, from a comparison of the two
analyses of Gubler and Quevenne, that the composition of the
lymph, even when it is unmixed with chyle, is subject to
great variations. The caseous matter given by Gubler and
Quevenne is probably equivalent to the albuminous matter
of other chemists.

The distinctive characters of the different principles
found in the lymph do not demand extended , considera-
tion, inasmuch as most of them have already been treated
of in connection with the blood. In comparing, however,
the composition of the lymph and the blood, we are at once
struck with the great excess of solid constituents in the latter
fluid. In the analyses of the serum of the blood by Bec-
querel and Rodier, the proportion of solid constituents was
ninety-two parts per 1,000 ; 1 while in the analyses of the hu-

the fluid, the reader is referred to the Gazette Nedicale, 1854, pp. 361, 403, 452,
and 516.

1 BECQUEREL ET EODIER, Chimie Pathologique, Paris, 1854, p. 86.

518 ABSORPTION.

man lymph by Gubler and Quevenne, the proportion was
from sixty to sixty-five parts per 1,000, and in the analysis
of Lheritier, which gives the largest quantities of solid mat-
ter, the proportion was between seventy-five and seventy-six
parts.1

In all analyses, except those of Lheritier, the organic ni-
trogenized compounds have been found to be very much less
in the lymph than in the blood. This is generally most
marked with regard to the fibrin ; but, as before stated, the
proportion of all these ingredients is quite variable. On ac-

1 A series of very elaborate analyses of the human lymph has recently been
made by Dahnhardt, under the direction of Professor Hensen. The fluid was col-
lected from a patient suffering from elephantiasis, or some analogous affection, in
which the lymphatics were found dilated. These observations have already been
referred to, and it is probable that the fluid obtained was not normal lymph. The
analyses, however, were exceedingly minute, especially as regards the proportions
of inorganic matters. The following is one of the analyses of this fluid :

Water 987*700

Fat 0-030

Organic extractives soluble in alcohol 1-284

Organic extractives soluble in water = extractive and albumen 0'908

Organic substances insoluble in water = fibrin and insoluble albumen. 1*699

r Chloride of sodium 6-148

Soda 0-576

Inorganic substances soluble I Potagh Q.493

mwater' 1 Carbonic acid 0-638

^Sulphuric and phosphoric acid and loss, 0-221

fChalk 0-132

Magnesia 0-011

Oxide of iron 0'006

Phosphoric acid 0*118

Carbonic acid 0'015

Carbonate cf magnesia, sulphuric acid,

and loss 0-021

Inorganic substances insolu-
uble in water,

1,000-000

DAHNHARDT, Ztur Chemie der Lymphe. — VIRCHOW'S Archiv, Berlin, 1866,

Bd. xxxvii., S. 55 et seq.

Analyses of the same lymph for organic matter, by Professor Hensen, give a
proportion of 1*070 of fibrin, 1-408 of serum-albumen, and 0-894 of albummous
compounds precipitated by acetic acid.

PKOPERTIES ANT> COMPOSITION OF LYMPH. 519

count of this deficiency in fibrin, lymph is much inferior to
the blood in coagulability, and the coagulum, when it is
formed, is soft and friable. There does not appear, however,
to be any actual difference between the coagulating principle
of the lymph and the fibrin of the blood.

Lassaigne found, in the lymph of the cow, that the quantity
of albumen was a little less than one-half the proportion con-
tained in the blood ; but in most analyses of human lymph,
the proportion has been much less. The analyses of Gubler
and Quevenne, however, give a somewhat greater quantity
of albuminoid matter (caseous matter), the proportion in one
analysis being 42-75, and in the other 42'80 parts per 1,000.
There appears, also, to be some difference between the albu-
minoid matter of the lymph and the albumen of the blood.
Gubler and Quevenne speak of the substance found in one
lymph as caseiform matter ; and Hensen speaks of a propor-
tion of serum-albumen and of albuminous matter precipitated
by acetic acid. The albuminoid matter of the lymph, there-
fore, would seem to possess certain distinctive characters ;
but we know so little of the function of this fluid, that it is
impossible to assign to these substances any special physio-
logical properties.

Fatty matters have generally been found more abun-
dantly in the lymph than in the blood ; but their proportion
is even more variable than that of the albuminoid substances.

Yery little remains to be said concerning the ordinary
inorganic constituents of the lymph. The analyses of Dahn-
hardt have shown that nearly, if not all, of the inorganic
matters which have been demonstrated in the blood are
contained in the lymph ; and even a small proportion of iron
is given in the analyses of Gubler and Quevenne.

These facts indicate a remarkable correspondence be-
tween the composition of the lymph and that of the blood.
All of the constituents of the blood exist in the lymph, the
only difference being in their relative proportions. It is the
same with the corpuscular elements ; for the so-called lymph-

520 ABSOKPTION.

corpuscles are identical with tlie leucocytes of the blood, and
the red disks frequently find their way from the blood-vessels
into the lymphatics.

In addition to the constituents of the lymph ordinarily
given, the presence of glucose, and more lately, the existence
of a certain proportion of urea, have been demonstrated in
this fluid. Brande, in 1812, noted the presence of sugar in the
chyle, but not in the lymph.1 It has since been demonstrated,
however, in the lymph, by Gubler and Quevenne,2 Poiseuille
and Lefort,3 Colin,4 and others. Poiseuille and Lefort found
that the proportion of sugar was always greater in the lymph
than in the chyle. The recent researches of Colin show that
the difference between the proportion of this substance in the
lymph and in the chyle is not very great, and its quantity
does not vary very considerably in different classes of ani-
mals. His observations were made upon horses, oxen, and
dogs, and the proportion of sugar varied between 1*02 and
1*58 parts per 1,000.5 It has not been ascertained how the
sugar contained in the lymph takes its origin, and its func-
tion in this situation is equally obscure.

The presence of urea in considerable quantity in both the
chyle and the lymph has been determined by Wurtz ; 6 and
it is thought by Bernard that the lymph is the principal

1 BRANDE, Chemical Researches on the Blood and some other Animal Fluids. —
Philosophical Transactions, London, 1812, p. 96.

Brande noticed crystals of what he supposed to be sugar of milk in the alco-
holic extract of the fluid taken from the thoracic duct four hours after feeding.

2 GUBLER ET QUEVENNE, op. cit. — Gazette Medicale de Paris, 1854, p. 454.
These observers, while admitting that the existence of sugar in the lymph is ren-
dered exceedingly probable — as the extract reduced a copper solution — did not
assume to have positively demonstrated its existence.

3 POISEUILLE ET LEFORT, De V Existence du Glycose dans V Organisme Animal.
— Comptes Rendus, Paris, 1858, tome xlvi., p. 567, and Note supplementaire, Ibid.,
p. 678.

4 COLIN, De I1 Origine du Sucre contenu dans le Chyle. — Journal de la Phy-
siologie, Paris, 1858, tome i., p. 539 etseq.

5 Loc. cit., p. 544.

6 BERARD, Formation Physiologique du Sucre dans V Economic Animate.—'

PROPERTIES AND COMPOSITION OF LYMPH. 521

fluid, if not the only one, by which this excrementitious sub-
stance is taken up from the tissues.1 Although urea always
exists in the blood, its quantity is less than in the lymph.2

The pathological alterations of the lymph have not been
experimentally investigated, if we except the early observa-
tions of Collard de Martigny upon the eifects of abstinence
upon the composition of this fluid. The experiments of this
observer upon the effects of abstinence upon the quantity
of lymph have already been referred to.3 "With regard to
the influence of this condition upon the composition of the
lymph, we may take the results of three analyses of the fluid
from dogs that had been without food, respectively, for thir-
ty-two hours, nine days, and twenty-one days.4

After 32 hours. After 9 days. After 21 days.

Water and salts 940-0 931-4 936-8

Fibrin 3'0 5'8 3'2

Albumen, fatty, and coloring matters. 57'0 62'S 60-0

Bulletin de VAcademie Imperiale de Medecine, Paris, 1856-'57, tome xxii., p.
784.

Wurtz discovered urea in a specimen of chyle brought to him by Berard for
examination, taken from a young bull. In less than a gramme of chyle, he dis-
covered large quantities of urea, and formed distinct crystals by combining it
with nitric acid. He believed that the urea came from the lymph and not from
the alimentary substances taken up from the intestine. This view was confirmed
by subsequent analyses, in which he discovered urea in the lymph of the dog, the
horse, and the ox. He found also that its proportion in the lymph was greater
than that naturally contained in the blood. (Written communication, in LONGET,
Traite de Physiologic, Paris, 1861, tome i., p. 429, note.)

1 BERNARD, Lemons sur les Proprietes Physiologiques el les Alterations Patho-
logiques dcs Liquides de V Organisme, Paris, 1859, tome ii., p. 27.

2 Wurtz, analyzing comparatively the blood, lymph, and chyle for urea, found
this substance in greatest proportion in the lymph. In a dog nourished with
meat, the proportion of urea was 0'089 parts per 1,000 in the blood and 0-158 in
the lymph ; in a cow, the proportion was 0*192 in the blood, 0*192 in the chyle,
and 0-193 in the lymph ; and in a ram, the proportion was 0-248 in the blood,
and 0-280 in the chyle. (Comptes Rendus, Paris, 1859, tome xlix., p. 53.)

3 See page 511.

4 COLLARD DE MARTIGNY, Rechercfies Experimental sur les Effets de V Absti-
nence complete d'Alimens solides et Jiquides, sur la Composition et la Quantite du
Sang et de la Lymphe. — Journal de Physiologie, Paris, 1828, tome viii., p. 182 et seq.

522 ABSOEPTION.

This table shows a certain concentration of the lymph
during the first periods of starvation ; but when the vital
powers had become very much reduced, and death, became
imminent, conjoined with a great diminution in the absolute
quantity of the lymph there was a notable reduction in the
proportion of its solid constituents.

The differences which the lymph presents in different ves-
sels relate chiefly to the abundance of its corpuscular ele-
ments. It has been said, however, that the quantity of
fibrin is greatest in the contents of the thoracic duct, and
that its proportion progressively increases from the periphery
to the large vessels.1 There is no positive evidence, however,
that fibrin is produced by the lymphatic glands, though this
theory has been advanced.

Corpuscular Elements of the Lymph. — In every part of
the lymphatic system, in addition to a few very minute fatty
granules, there are found certain corpuscular elements
known as the lymph-corpuscles. These exist, not only in
the clear lymph, but in the opaque fluid contained in the lac-
teals during absorption. They are now regarded as identical
with the colorless globular corpuscles found in the blood,
known under the name of white blood-corpuscles, or leu-
cocytes. Although these bodies have been pretty fully de-
scribed in treating of the corpuscular elements of the blood,"
they present some peculiarities in the lymphatic system, par-
ticularly in their development, which demand consideration.

The leucocytes found in the lymph and chyle are rather
less uniform in size and general appearance than the white
corpuscles of the blood. Their average diameter is about ¥ 3V ¥
of an inch ; but some are larger, and others are as small as
5 oVo- °f an inch. Some of these corpuscles are quite clear
and transparent, presenting but few granulations and an in-
distinct nuclear appearance in their centre; but others are

1 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 413.
8 See vol. i., p. 121.

COKPUSCTTLAB ELEMENTS OF THE LYMPH. 523

granular and quite opaque. They present the same adhe-
sive character in the lymph that we have noted in the blood,
and frequently are found collected in masses in different
parts of the lymphatic system.1 Treated with acetic acid,
the corpuscles generally become swollen, and are rendered
very transparent, then presenting from one to four or five
nuclear concretions in their interior. In all other regards,
these bodies present the same characters as the leucocytes of
the blood, and need not, therefore, be further described.

We have already alluded to the fact that the lymph-cor-
puscles are more abundant in the larger than in the smaller
vessels ; and "that they have been thought to be particularly
numerous in the vessels coming from the lymphatic glands.
It is nevertheless true that corpuscles exist even in the
smallest vessels, and they are sometimes quite abundant in
lymph which has not passed through any glands. These
considerations naturally lead to the theory of the develop-
ment of leucocytes in the lymphatics, as well as in the or-
dinary vascular system, particularly as the constant dis-
charge of lymph and chyle into the blood-vessels renders it
more than probable that most of the leucocytes found in the
blood are derived from the lymph.

The late researches of Robin, and others, by whom his
observations have been somewhat extended, have conclu-
sively demonstrated that leucocytes may be developed, under
proper conditions, in a clear structureless blastema, without
the intervention of any glandular organ ; and, furthermore,
it is not necessary that the blastema should be enclosed in
any system of vessels. These facts refute completely the idea
that the lymph-corpuscles are formed either by the lymphatic
glands or by the walls of the lymphatic vessels. Observa-
tions have also shown that leucocytes exist in the blood ot
the embryo before any lymphatic vessels can be demon-

1 ROBIN, Sur quelques Points de VAnalomie et dc la Physiologic des Leucocytes
ou Globules blancs du Sang. — Journal de la Physiologic, Paris, 1859, tome ii., p.
44.

524: ABSOEPTION.

strated ; 1 a fact which shows that these bodies may be devel-
oped de novo in the blood-plasma.

Of these facts there can be no doubt ; and since the publi-
cation of the first volume of this work, additional experiments
upon the development of leucocytes in clear fluids have not
only confirmed the views which we adopted with regard to
the origin of these bodies in the blood and elsewhere, but
have defined more closely the conditions under which such
development may take place. We refer particularly to the
observations of Onimus upon the genesis of leucocytes and
upon spontaneous generation.2 These experiments are all
the more striking in their application to the development of
the lymph-corpuscles, as they were made with the clear
fluid effused from the blood by vesication, and as recent facts
with regard to the relative anatomy of the smallest lymphat-
ics and the blood-vessels render it probable that the lymph
is in great part derived from liquid elements which pass out
of the blood by exosmosis.

Onimus used the clear fluid taken without delay from
rapidly developed blisters, which he found ordinarily con-
tained no leucocytes, but which he carefully filtered in order
to remove all sources of error. The filtered liquid contained
no morphological element whatsoever ; but, on the other
hand, he found that if the liquid were allowed to remain for
an hour or more in contact with the dermis, it always con-
tained leucocytes and epithelial cells. Under these circum-
stances, even after filtration, the liquid contained a few leuco-
cytes ; but after six or seven hours of repose in a conical vessel,
the corpuscular elements gravitated to the bottom, leaving
the upper portion of the liquid perfectly clear.

This liquid, entirely free from formed anatomical ele-
ments, was enclosed in little sacs formed of an animal mem-

1 ROBIN, op. cit. — Journal de la Physiologic, Paris, 1859, tome ii., p. 49,

a ONIMUS, Experiences sur la Genese dcs Leucocytes et sur la Generation Spon-

tanee. — Journal de VAnatomie et de la Physiologic, Paris, 1867, tome iv., p. 47

et seq.

COKPUSCULAR ELEMENTS OF THE LYMPH. 525

brane (goldbeater's skin) and introduced tinder the skin of a
living rabbit. At the end of twelve hours, a few small leuco-
cytes and granulations had made their appearance ; at the
end of twenty-four hours, the fluid had become somewhat
opaque and contained a large number of leucocytes and
granulations ; and at the end of thirty-six hours, the fluid
was white, milky, and composed almost entirely of leucocytes
and granulations. The leucocytes, which were examined also
by Robin, presented all the characters by which these cor-
puscles are ordinarily recognized. These experiments were
repeated with more than forty different specimens of fluid
from blisters.

The experiments were then varied in order to show the
influence of the membrane and of the composition of the
blastema upon the development of leucocytes. By modi-
fying the membrane in which the blastema was enclosed,
it was found that the corpuscles were rapidly developed
in proportion to the activity of the osmotic action. "When
thick animal membranes were used, their development was
slow, and in some instances did not take place at all. There
was no development of leucocytes in a clear blastema enclosed
in a sac of caoutchouc or in glass tubes hermetically sealed ;
and from this it was concluded that the osmotic action was a
necessary condition, and that the mere heat of the body was
not sufficient to develop these corpuscles, even in an appro-
priate blastema. The influence of this constant molecular
movement is in striking contrast to the conditions of absolute
repose which are so essential to the formation of crystals
from ordinary saline solutions.

One of the most interesting points in these experiments
is connected with the influence of the composition of the
blastema upon the development of leucocytes. It was found
that these bodies were never developed in a blastema in
which the fibrin had been coagulated. Experimenting with
two liquids, the only difference in their constitution being
that in one the fibrin had been coagulated by repeatedly

526 ABSORPTION.

plunging the glass tube in which it was contained into cool
water, while the other was kept at the ordinary temperature,
a little bicarbonate of soda being added to prevent coagula-
tion, it was found that leucocytes were developed as usual in
the fluid which contained its fibrin, and that none appeared
in the other. On placing the liquid with its coagulum en-
closed in a sac under the skin, it was found that after a time
the fibrin was redissolved, but no leucocytes made their ap-
pearance.

The theory which has for its motto, omnis cellula e cellula,
receives no support from these experiments. Onimus added
to fluids which had been deprived of their fibrin, epithelial
cells and pus-corpuscles, but even after thirty-six hours, he
never found any additional development of corpuscular ele-
ments. Leucocytes added to fluids in which the fibrin was
unchanged did not seem to exert any influence upon the de-
velopment of new corpuscles.

As regards the lymph, there is no fluid in the body which
is placed under conditions more favorable to the development
of leucocytes. It is enclosed in a system of vessels possess-
ing extremely thin walls, and undoubtedly subjected to active
osmotic currents. It contains, likewise, a considerable quan-
tity of fibrin; and the proportion of this principle has
always been found to influence the rapidity of the develop-
ment of white corpuscles. Its circulation is not very rapid,
and the obstacles to the current which are presented in the
lymphatic glands undoubtedly give time for the perfection in
the structure of leucocytes. It is in this way that the in-
crease in the number of leucocytes as the lymph passes from
the periphery to the larger vessels, and especially as the fluid
passes through the glands, can be explained.

. From the fact that leucocytes are developed before the lym-
phatic system makes its appearance, that they are found in
lymph which has never passed through lymphatic glands, and
from the observations just cited showing their spontaneous
formation in an amorphous blastema, it is the inevitable con-

ORIGIN AND FUNCTION OF THE LYMPH. 527

elusion that nearly, if not quite all, of the lymph-corpuscles
are developed by genesis in the clear lymph-plasma, and that
their development goes on as the fluid circulates toward the
venous system. With regard to the influence of the lym-
phatic glands upon the generation of leucocytes, there is no
evidence that the corpuscles which are developed in the
course of the lymph through these organs are not here, as
elsewhere, formed simply from the blastema ; and it is not
necessary to invoke any special formative action taking place
in the peculiar structures of the glands.

The function of the lymph-corpuscles is obscure. They
are discharged into the blood, of which they form a constant
constituent. Aside from the hypothesis that they are con-
cerned in the formation of the red blood-disks, no definite
and reasonable theory of their physiological office has been
proposed.

In addition to the ordinary leucocytes and a certain num-
ber of fatty granules, a few small clear globules or granules,
about TjVo- of an inch in diameter, called sometimes globu-
lins, are almost constantly present in the lymph. These are
insoluble in ether and acetic acid, but are dissolved by am-
monia. They are regarded by Robin as a variety of leuco-
cytes and are described by him as free nuclei. They make
their appearance in the blastema before the larger leucocytes
are developed.

Origin and Function of the Lymph. — There can hardly
be any doubt concerning the source of most of the liquid
portions of the lymph, for they can be derived only from the
blood. Although the exact relations between the smallest
lymphatics and the blood-vessels have not been made out in
all parts of the system, there is manifestly no anatomical
reason why the water, mixed with albumen and fibrin and
holding salts in solution, should not pass from the blood into
the lymphatics ; and this is rendered nearly certain if it
can be demonstrated that the lymphatics partly or entirely

528 ABSOEPTION.

surround many of the blood-vessels ; for under these circum-
stances, endosmotic and exosmotic currents would inevita-
bly take place. We have seen, in comparing the composi-
tion of the lymph with that of the plasma of the blood, that
the constituents of these fluids are nearly if not quite identi-
cal ; the only variations being in their relative proportions.
This is another strong argument in favor of the passage of
most of the constituents of the blood into the lymph. The
difference in the proportion of albumen is explained by the
fact that this substance is but slightly exosmotic ; and with
regard to the proportion of fibrin, it is pretty well estab-
lished that, in the blood, this principle is formed by a trans-
formation of albumen. The same may occur in the lymph,
particularly as the quantity of fibrin has been found to in-
crease as the liquid passes from the periphery to the larger
vessels.

One of the most important physiological facts in the
chemical history of the lymph is the constant existence of a
considerable portion of urea. This cannot be derived from
the blood, for its proportion is greater in the lymph,1 not-
withstanding that this fluid is being constantly discharged
into the blood-vessels. The urea which exists in the lymph
is derived from' the tissues ; it is discharged then into the
blood, and is constantly being removed from this fluid by the
kidneys.

The positive facts upon which to base any precise ideas with
regard to the general function of the lymph are not very nu-
merous. From the composition of this fluid, its mode of circu-
lation, and the fact that it is being constantly discharged into
the blood, it would not seem to have an important function
in the active processes of nutrition. The experiments of Col-
lard de Martigny sustain this view, inasmuch -as the quan-
tity and the proportion of solid constituents of the lymph
were rather increased than diminished in animals that had

1 WURTZ, written communication, in LOXGET, Traite de Pliytiologie, Paris,
1861, tome i., p. 429, note.

CHYLE. 529

been deprived of food and drink for several days ; while it
is well known that starvation always impoverishes the blood.1
On the other hand, urea, one of the most important of the pro-
ducts of destructive metamorphosis of the tissues, is undoubt-
edly taken up by the lymph, and conveyed in this fluid to
the blood. It remains now for future investigations to deter-
mine whether other excrementitious principles may not be
taken up from the tissues in the same way — a question of
great importance in its relations to the mechanism, of excre-
tion.

What is positively known with regard to the functions
of the lymph may be summed up in a very few words : A
great part of its constituents is evidently derived from the
blood; and the relations of these principles (fibrin, albumen,
and the ordinary inorganic salts) to nutrition are not under-
stood. The same may be said of sugar, also a constant con-
stituent of the lymph, the origin of which, even, is not known.
Urea and, perhaps, other excrementitious matters are taken
up from the tissues by the lymph, and are discharged into
the blood, to be removed by the appropriate organs from the
system.

While the blood is evidently the great nutritive fluid of
the body, being constantly regenerated and purified by the
absorption of nutritive matters, by respiration, and by the
action of excreting organs, the lymph has an important
function in removing from the tissues some, at least, of the
products of physiological decay of the organism.

Chyle.

During the intervals of digestion, the intestinal lymphat-
ics and the thoracic duct carry ordinary lymph ; but as soon
as absorption of alimentary matters begins, certain nutritive
principles are taken up in quantity by these vessels, and
their contents are now known as the chyle. But little re-
mains to be said concerning this fluid, as we have consid-

1 Loc. cit.
34

530 ABSOEPTKXfr.

ered pretty fully the composition and properties of the
lymph as well as the different principles taken up by the
lacteal vessels which, with the lymph, form the chyle.
Some general considerations, however, remain concerning
the composition and properties of the chyle- as a distinct
fluid.

In the human subject and in carnivorous animals, the
chyle taken from the lacteals near the intestine, where it is
nearly pure, or from the thoracic duct, when it is mixed with
lymph, is a white, opaque, milky fluid, of a slightly saline
taste, and an odor which is said to resemble that of the semen.
The odor is also said to be characteristic of the animal from
which the fluid is taken ; although this is not very marked,
except on the addition of concentrated acid, the process^ em-
ployed by Barreul to develop the characteristic odor in the
fluids from different animals.1 Bouisson has found that the
peculiar odor of the dog was thus developed in fresh chyle
taken from the thoracic duct of this animal.2

The chyle taken from a fistula into the thoracic duct is
frequently of a more or less rosy tint ; and it has been a
question whether this be due to a peculiar coloring matter or
to the accidental presence of a few red blood-corpuscles.
Colin, whose experiments in collecting chyle from living
animals have been very numerous and successful, assumes
that the red coloration is always due to blood-corpnscles
coming from the subclavian vein ; the valve at the orifice of
the thoracic duct not being always sufficient to prevent re-
gurgitation. He has never found blood in the fluid taken
from the mesenteric vessels or the receptaculum chyli. and he
states, furthermore, that the chyle from these vessels never
becomes colored under the influence of the air or of oxygen.3

1 See vol. i., p. 67.

2 BOUISSON, Eludes sur le Chyle. — Gazette Hedicale de Paris, 1844, tome xii.,
p. 412.

3 COLIN, Traile de Physiologic Comparee des Animaux Domestiques, Paris,
1856, tome ii., p. 7.

CHYLE. 531

Dalton and others have noted the same fact, and have ob-
served that the fluid which is first discharged after a tube is
fixed in the thoracic duct is perfectly white, the rosy tint
gradually appearing as the chyle flows from the fistula.1
These views with regard to the coloration of the chyle after its
discharge from the vessels are stated positively, as the result
of numerous experiments ; and there is every reason for sup-
posing that they are correct, notwithstanding that Longet
and some others have assumed that the chyle becomes tinged
with red as the result of a transformation of a coloring mat-
ter peculiar to this fluid, " a matter with regard to the origin
and nature of which we are not yet certain." 2

The reaction of the chyle is either alkaline or neu-
tral.3 Dalton noted an alkaline reaction in the chyle of
the goat and of the dog ; * and a specimen of chyle taken
from a criminal immediately after execution, and examined
by Bees, was neutral.6 Leuret and Lassaigne obtained the
fluid from the receptaculum chyli in a man that had died
of cerebral inflammation, and found its reaction to be al-
kaline.8

The specific gravity of the chyle is always less than that
of the blood ; but it is very variable, and depends upon the
quality of the food and particularly upon the quantity of
liquids ingested. Lassaigne found the specific gravity of a
specimen of pure chyle taken from the mesenteric lacteals of

1 DALTON, Lectures on the Physiology of the Circulation. — American Medical
Monthly and New York Review, December, 1860, p. 409.

2 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 423.

3 Tiedemann and Gmelin found the fluid collected from the thoracic duct of a
dog, four hours after eating, to be alkaline. (TIEDEMANN ET GMELIN, Recherches
sur la Route que prennent diverses Substances pour passer de VJEstomac et du Ca-
nal Intestinal dans le Sang, etc., Paris, 1821, p. 4.)

4 Loc. cit.

5 REES, On the Chemical Analysis of the Contents of the Thoracic Duct in tlie
Human Subject. — Philosophical Transactions, London, 1842, p. 8.

6 LEURET ET LASSAIGNE, Recherches Physiologiques et Chimiques pour servir
d FHistoire de la Digestion, Paris, 1825, p. 165.

532 ABSOEPTION.

a bull to be 1,01s,1 and the specific gravity of the specimen
of human chyle examined by Rees was 1,024.2

The differences in the appearance of the chyle in dif-
ferent animals depend chiefly upon the diet. Colin found
it excessively milky in the carnivora, especially after fats
had been taken in quantity ; while in dogs that were nour-
ished with articles containing but little fat, its appearance
was hardly lactescent.3 Tiedemann and Grnelin found the
chyle almost transparent in herbivora fed with hay or straw.
They also observed the fact that the chyle was nearly trans-
parent in dogs fed with liquid albumen, fibrin, gelatine,
starch, and gluten ; while it was white in the same animals
fed with milk, meat, bones, etc.4

It is impossible to give even an approximative estimate
of the entire quantity of pure chyle taken up by the lacteal
vessels. "When it finds its way into the thoracic duct, it is
mingled immediately with all the lymph from the lower ex-
tremities; and the immense quantities of fluid which have
been collected from this vessel by Colin and others,6 give
no idea of the quantity of chyle absorbed from the intes-
tinal canal. We cannot, therefore, attempt even to give an
approximate estimate of absolute quantity of chyle ; but it is
evident that this is variable, depending upon the nature of
the food and the quantity of liquids ingested.

Like the lymph, the chyle, when removed from the ves-
sels, speedily undergoes coagulation. Different specimens
of the fluid vary very much as regards the rapidity with
which coagulation takes place. The contents of the thoracic
duct taken from the inferior animals generally coagulates in
a few minutes. The first portion of the fluid collected from

1 COLIN, op. cit., tome ii., p. 7.

2 Loc. cit.

8 Op. cit., p. 8.

4 TIEDEMANN ET GMELIN, Recherches Experimentales Physiologiques et Chi*
miqucs sur la Digestion, Paris, 1827, premiere partie, p. 176 et seg., and p. 308.
6 See page 509.

COMPOSITION OF THE CHYLE. 533

the human subject by Dr. Rees (the chyle was collected in
this case in two portions) coagulated in an hour.1 Received
into an ordinary glass vessel, the chyle generally separates
more or less completely after coagulation into clot and
serum, the density and size of the clot indicating the pro-
portion of fibrin. The serum which thus separates is quite
variable in quantity, and is never clear. Its milldness does
not depend entirely upon the presence of particles of emul-
sified fat, and it is not rendered transparent by ether; it
contains, in addition to these particles', numerous leucocytes
and organic granules.

Numerous observations have been made with reference
to the influence of different kinds of food upon the chyle ;
but these have not been followed by any definite results that
can be applied to the human subject. It is usual to find the
chyle fluid in the lacteals and the thoracic duct for many
hours after death ; but it soon coagulates upon exposure to
the air. Although the entire lacteal system is sometimes
found, in the human subject and in the inferior animals, filled
with perfectly opaque coagulated chyle,2 the fluid does not
often coagulate in the vessels.

Composition of the Chyle. — Analyses of the milky fluid
taken from the thoracic duct during full digestion by no
means represent the composition of pure chyle ; and it is
only by collecting the fluid from the mesenteric lacteals, that
it can be obtained without a very large admixture of lymph.
In the human subject, it is rare even to have an opportunity
of taking the fluid from the thoracic duct in cases of sudden
death during digestion ; and in most of the inferior animals
which have been operated upon, it is difficult to obtain fluid
from the small lacteals in quantity sufficient for accurate

1 REES, On the Chemical Analysis of the Contents of the Thoracic Duct in the
Human Subject. — Philosophical Transactions, London, 1842, p. 82.

2 CRTJIKSHANK, TJie Anatomy of the Absorbing Vessels of the Human
London, 1790, p. 101.

534: ABSORPTION.

analysis. In operating upon the ox, however, Colin lias suc-
ceeded in collecting pure chyle in considerable quantity. In
this animal, the lacteals are not numerous, but are of consid-
erable size, and unite into a large trunk which follows the
course of the mesenteric artery and vein. On introducing, in
the living animal, a tube into this trunk or into one of its
large tributaries, a considerable quantity of fluid may be col-
lected in a very few minutes.

The chyle of the ox, collected in this way by Colin, was
examined by Lassaigne, but unfortunately no complete anal-
ysis was made. The fluid contained 1*9 parts per 1,000 of
dried fibrin, which wras double the quantity found in the
fluid from the thoracic duct of the same ruminant. The
serum contained 952'1 parts of water and 47*9 parts of solid
matters — albumen and salts.1 Although the analysis of this
fluid was not completed, it evidently contained all the organic
and inorganic principles which exist in pure lymph and in
the contents of the thoracic duct. Remembering, then, that
even during the period of greatest activity in the absorption
of alimentary matters, the contents of the thoracic duct con-
sist largely of lymph, we must take the analyses of this mixed
fluid as our only data for forming an approximative estimate
of the proportions of the various constituents of the chyle.
It must be borne in mind, also, that the composition of the
chyle is constantly varying with the diet. As we have al-
ready shown in treating of absorption, many of the aliment-
ary principles may be actually recognized in the fluid ob-
tained from the lacteals during digestion and absorption.2

The most complete analysis of chyle from the human
subject is given by Dr. Rees.3 Tb.e fluid was taken from the
thoracic duct of a vigorous man, a little more than an hour

1 COLIN, Traite de Physiologic Comparee des Animaux Domestiques, Paris,
1856, tome ii., p. 7.

2 See page 445 etseq.

" REES, On the Chemical Analysis of the Contents of the Tlioradc Dud in lh«
Human Subject. — Philosophical Transactions, London, 1842, p. 81 et seq.

. COMPOSITION OF THE CHYLE. 535

after his execution by hanging. The subject was apparently
in perfect health up to the moment of his death. The evening
before, he ate two ounces of bread and four ounces of meat.
At seven o'clock A. M., precisely one hour before death, he
took two cups of tea and a piece of toast ; and he drank a
glass of wine just before mounting the scaffold. When the
dissection was made, the body was yet warm, although the
weather was quite cold. The thoracic duct was rapidly
exposed and divided, and about six fluidrachms of milky
chyle were collected. The fluid was neutral, and had a spe-
cific gravity of 1,024. The following was its proximate com-
position :

Composition of Human Chyle from the Thoracic Duct.

Water 904-8

Albumen, with traces of fibrinous matter '. 7O8

Aqueous extractive 5'6

Alcoholic extractive, or osmazome 5'2

Alkaline chloride, carbonate, and sulphate, with traces of alkaline

phosphates and oxides of iron 4'4

Fatty matters 9-2

1,000-0

Of the constituents of the chyle not given in the ordinary
analyses, the most important are the urea, which is derived
exclusively from the lymph, and sugar, coming from the sac-
charine and amylaceous articles of food during the digestion
of these principles.

The difference in chemical composition between the un-
mixed lymph and the chyle is very well illustrated in a com-
parative examination of these two fluids taken from a don-
key. The fluids were collected by Mr. Lane, the chyle being
taken from the lacteals before reaching the thoracic duct.
The animal was killed seven hours after a full meal of oats
and beans. The following analyses of the fluids was made
by Dr. Kees : *

1 REES, On Chyle and Lymph. — London Medical Gazette, 1841, vol. xxvii., p.
547; and LANE, Lymphatic and Lacteal System. — Cyclopaedia of Anatomy and
Physiology, London, 1839-1847, vol. iii., p. 223.

536 ABSOBPTION.

Composition of Chyle and Lymph before reaching the Tho-
racic Duct.

Chyle. Lymph.

Water ............................................ 902-37 965-36

Albuminous matter ................................. 35-16 12-00

Fibrinous matter ........ 9 ..... , .................... 3-70 1-20

Animal extractive matter soluble in water and alcohol. . . 3'32 2*40

Animal extractive matter soluble in water only . . . ....... 12-33 13-19

Fatty matter ...................................... 36'01 a trace

j Alkaline chloride, sulphate and carbonate, with j ^ ,, g.gg

, )

traces of alkaline phosphate, oxide of iron,

1,000-00 1,000-00

The above analysis shows a very marked difference in the
proportion of solid constituents in these two fluids. The
chyle contains about the same proportion of albumen and
fibrin as the lymph, and a much larger proportion of salts.
The proportion of fatty matters in the chyle is very great,
while in the lymph there exists only a trace.1

The individual constituents of the chyle given in the
above tables do not demand any further consideration than
they have already received under the head of lymph. The
albuminoid matters are in part derived from the food, and in
part from the blood, through the admixture of the chyle
with lymph. The fatty matters are derived in greatest part
from the food. As far as has been ascertained by analyses of
the chyle for salts, this fluid has been found to contain essen-
tially the same inorganic constituents as the plasma of the
blood. All of these principles are rapidly poured into the
blood, where they assist in supplying the material which is
being constantly consumed in the process of nutrition.

1 The proportion of fat given in this analysis of the chyle is even greater than
the proportion given by Nasse in an analysis of the chyle of the cat, which ia
very commonly quoted as a specimen of chyle extraordinarily rich in fatty mat-
ters. The probable explanation of the large proportion of fat found by Kees is
that the fluid was taken from the lacteals, and was not mixed with lymph in the
thoracic duct. The proportion of fat in the analysis made by Nasse was 32-7
parts per 1,000. (NASSE, Chylus — WAGNER'S Handworterluch der Physiologie,
Braunschweig, 1842, Bd. i., S. 235.)

MICROSCOPICAL CHARACTERS OF THE CHYLE. 537

The presence of sugar in the chyle was first mentioned
by Brande, who described it, however, rather indefinitely.1
Glncose was distinctly recognized in the chyle by Trommer,2
and its existence in many of the higher orders of animals has
since been fully established by Colin.3

Microscopical Characters of the Chyle. — The milky ap-
pearance of the chyle as contrasted with the lymph is due to
the presence of an immense number of excessively minute fatty
granules. The liquid becomes much less opaque when treated
with ether, which dissolves many of the fatty particles. In fact,
the chyle of the thoracic duct is nothing more than lymph to
which an emulsion of fat in a liquid containing fibrin, albu-
men, and salts is temporarily added during the process of
intestinal absorption. The quantity of fatty granules in the
chyle varies considerably with the diet, and generally dimin-
ishes progressively from the smaller to the larger vessels, on
account of the constant admixture of lymph. The size of
the granules is pretty uniformly from ^jloQ ^° TYJO ¥ of an
inch.* They are much smaller and more uniform in size in
the lacteals than in the cavity of the intestine. Their con-
stitution is not constant ; and they are composed of the dif-
ferent varieties of fat which are taken as food, mixed to-
gether in variable proportions. This fact was well illustrated
in the experiments of Bouchardat and Sandras, who even
detected certain peculiar kinds of fat which had been fed to
dogs, in the contents of the lacteals and the thoracic duct.5

1 BRANDE, Chemical Researches on the Blood and some othfr Animal Fluids. —
Philosophical Transactions, London, 1812, p. 96.

2 TROMMER, Unterscheidung von Gfummi, Dextrin, Traubenzwcker, und Rohr-
zucker. — Annalen der Chemie und Pharmacie, Heidelberg, 1841, Bd. xxxix.,
S. 360.

3 COLIN, De V Origine du Sucre contenu dans le Chyle. — Journal de la Physi-
ologic, Paris, 1858, tome i., p. 539 et seq.

4 ROBIN, in NYSTEN'S Didionnaire de Medecine, Paris, 1865, article Chyle.

6 BOUCHARDAT ET SANDRAS, Recherches sur la Digestion et V Assimilation des
Corps gras. — Annuaire de Therapeutique, Paris, 1845, p. 242 et seq.

538 ABSORPTION.

The ordinary corpuscular elements of the lymph — leuco-
cytes and globulins — are also found in variable quantity in
the chyle. These have already been fully considered.

Movements of the Lymph and the Chyle.

Compared with the current of blood, the movements of
the lymph and chyle are feeble and irregular ; and the char-
acter of these movements is such that they are evidently due
to a variety of causes. As regards those elements which are
derived directly from the blood, the lymph may be said to
undergo a true circulation ; inasmuch as there is a constant
transudation at the peripheral portion of the vascular system
of fluids which are returned to the circulating blood by the
communications of the lymphatic system with the great
veins. But we have seen that the lymph is not derived en-
tirely from the blood, a considerable portion resulting from
interstitial absorption in the general lymphatic system, and
from the absorption of certain nutritive matters by the chy-
liferous vessels. These are, physiologically, the most impor-
tant constituents of the lymph and chyle ; and they are
taken up simply to be carried to the blood, and do not pass
again from the general vascular system into the lym-
phatics.

As far as the mode of origin of the lymph and chyle has
any bearing upon the movements of these fluids in the
lymphatic vessels, there is no difference between the imbibi-
tion of new materials from the tissues or from the intestinal
canal, and the transudation of the liquid portions of the
blood ; for the mechanism of the passage of liquids from the
blood-vessels is such that the motive power of the blood can-
not be felt. An illustration of this is in the mechanism of
the transudation of the liquid portions of the secretions. The
force with which fluids are discharged into the ducts of the
glands is enormous, and is independent of the action of the
heart ; being due entirely to the force of transudation and
secretion. This is combined with the force of imbibition,

MOVEMENTS OF THE LYMPH AND THE CHYLE. 539

and with it forms one of the important agents in the move-
ments of the lymph and chyle.

These movements are studied with great difficulty. One
of the first peculiarities to be observed is, that under normal
conditions, the vessels are seldom distended ; and the quan-
tity of fluid which they contain is subject to considerable
variation. As far as the flow in the vessels of medium size
is concerned, the movement is probably continuous, subject
only to certain momentary obstructions or accelerations from
various causes. But in the large vessels situated near the
thorax, and in those within the chest, the movements are in
a marked degree remittent, or may even be intermittent.
All experimenters who have observed the flow of lymph or
chyle from a fistula into the thoracic duct have noted a con-
stant acceleration with each act of expiration ; and an im-
pulse synchronous with the pulsations of the heart has been
frequently observed.

The fact that the lymphatic system is never distended,
and the existence of the numerous valves by which different
portions may become isolated, render it impossible to esti-
mate the general pressure of fluid in these vessels. This is
undoubtedly subject to great variations in the same vessels at
different times, and in different parts of the lymphatic sys-
tem. It is well known, for example, that the amount of dis-
tension of the thoracic duct is exceedingly variable, its capa-
city not infrequently being many times increased during
active absorption. At the same time it is difficult to attach
a manometer to any part of the lymphatic system without
seriously obstructing the circulation, and consequently ex-
aggerating the normal pressure. But the force with which
liquids penetrate these vessels is very great. This is illus-
trated by the experiment of ligating the thoracic duct ; for
after this operation, unless communicating vessels exist by
which the fluids can be discharged into the venous system,
their accumulation is frequently sufficient to rupture the
vessel. %

54:0 ABSORPTION.

The general rapidity of the current in the .lymphatic
vessels has never been accurately estimated. As a natural
consequence of the variations in the distention of these ves-
sels, the rapidity of the circulation must be subject to con-
stant modifications. Beclard, making his calculation from
the experiments of Colin, who noted the quantity of fluid dis-
charged in a given time from fistulous openings .into the
thoracic duct, estimates that the rapidity of the flow in this
vessel is about one inch per second.1 This estimate, how-
ever, can be only approximative ; and it is evident that the
flow must be much less rapid in the vessels near the pe-
riphery than in the large trunks, as the liquid moves in a
space which becomes rapidly contracted as it approaches the
openings into the venous system.

Causes of the Movements of the Lymph and Chyle.

Various influences combine to produce the movements of
fluids in the lymphatic system, some being constant in their
operation, and others intermittent or occasional. These will
be considered, as nearly as possible, in the order of their rel-
ative importance.

Influence of the Forces ofEndosmosis and Transudation
(vis a tergo). — The forces of endosmosis and transudation are
undoubtedly the main causes of the lymphatic circulation,
more or less modified, however, by influences which may
accelerate or retard the current ; but this action is capable in
itself of producing the regular movement of the lymph and
chyle. It is a force which is in constant activity, as is seen
in cases of ligation of the thoracic duct, an operation which
must finally abolish all other forces which aid in producing
the lymphatic circulation. "When the receptaculum chyli is
ruptured, as a consequence of obstruction of the thoracic duct,
the vessel gives wray as the result of the constant endosmotic

1 BECLARD, Iraite tilementaire de Physiologic Humaine, Paris, 1859, p. 180.

INFLUENCE OF ENDOSMOSIS AND TEANSUDATION.

action, in the same way that the exposed membranes of an
egg may be ruptured by endosmosis, when immersed in
water.

We have already alluded to the influence of transudation
from the blood-vessels, and compared it to the force with which
the secretions are discharged into the ducts of the glands ; and
in placing this, with the force of endosmosis, at the head of the
list of the agents which effect the lymphatic circulation, its
importance is not over-estimated. This conclusion can hardly
be avoided, when we consider the anatomy of the lymphatic
system. The situations in which the endosmotic force ori-
ginates are at the periphery, where the single homogeneous
wall of the plexus is excessively thin, and the extent of
absorbing surface is enormous. If liquids can penetrate with
such rapidity and force through the walls of the blood-ves-
sels, where their entrance is opposed by the pressure of the
fluids already in their interior, they certainly must pass with-
out difficulty through the walls of the lymphatics, where
there is no lateral pressure to oppose their entrance, except
that produced by the weight of the column of liquid. This
pressure is readily overcome ; and the numerous valves in
the lymphatic system effectually prevent any backward cur-
rent. Every particle of liquid that passes into the lymphat-
ics by endosmosis or by transudation, produces movement by
displacing an equal bulk of liquid contained in the vessel.
We observe with the microscope the rapid filling and rup-
ture of microscopic cells when immersed in water ; and the
rough experiments by which the operation of endosmosis is
ordinarily illustrated, in which the extent of endosmotic sur-
face is infinitely small compared with the lymphatic system,
exhibit a current of considerable force and rapidity. When
we remember that the infinitely numerous lymphatic radi-
cles are bathed in fluids, which undoubtedly pass into their
interior with great facility, and compare the probable extent
of this endosmotic surface with the diameter of the thoracic
duct, we can hardly be surprised that this force should be ca-

54:2 ABSOEPTIOK.

pable of producing a movement in the great trunk at the rate
of an inch per second. The great elasticity of the vessels
and the fact that they are never completely filled allow of
considerable distension of isolated portions of the lymphatic
system, when there is any obstruction to the current that is not
readily overcome. In this way we account for the variations
in the flow of the lymph and chyle which are of such con-
stant occurrence.

Influence of the Contractile Walls of the Vessels.— In.
treating of the anatomy of the lymphatic system, it has
already been observed that .the large vessels and those of
medium size are provided with unstriped muscular fibres,
and are endowed with contractility.1 This fact has been
demonstrated by physiological as well as anatomical investi-
gations. Beclard states that he has often produced contrac-
tions of the thoracic duct by the application of the two poles
of an inductive apparatus.2 It is not uncommon to see
the lacteals become reduced in size to a mere thread, even
while under observation. Although experiments have gen-
erally failed to demonstrate any regular rhythmical contrac-
tions in the lymphatic system,3 it is probable that the vessels
contract upon their contents, when they are unusually dis-
tended, and thus assist the circulation, the action of the
valves opposing a regurgitating current. This action, how-
ever, cannot have any considerable and regular influence
upon, the general current.4

1 See page 43*7.

2 BECLARD, Traite filementaire de Physiologie Humaine, Paris, 1859, p. 177.

s COLIN is quoted as having observed rhythmical contractions in the mesen-
teric lymphatics in the ox ; but as far as we know, his experiments have not been
published. (LABEDA, Systime Lymphatique, Cours du Chyle et de la Lymphe,
Paris, 1866, p. 63.)

4 In some of the lower vertebrate animals, in which the lymphatic vessels
have no valves, there exist several contractile dilatations, or hearts, which are
provided with valves, and which pulsate regularly. These were discovered by
Miiller, in 1832, in frogs, toads, and lizards. (MULLER, Manuel de Physiologiey

INFLUENCE OF PRESSURE FROM SURROUNDING PARTS. 543

Influence of Pressure from Surrounding Parts. — Con-
tractions of -the ordinary voluntary muscles, compression of
the abdominal organs by contraction of the abdominal mus-
cles, peristaltic movements of the intestines, and pulsations
of large arteries situated against the lymphatic trunks, par-
ticularly the thoracic aorta, are all capable of increasing the
rapidity of the circulation of the lymph and chyle.

The contractions of voluntary muscles assist the lym-
phatic circulation in precisely the same way in which they
influence the flow of blood in the venous system ; and we
have nothing to add regarding this action to what has al-
ready been said on this subject in connection with the
venous circulation.1 The fact that muscular movements
actually accelerate the flow of lymph has been conclusively
demonstrated by Colin, who found that when a tube was
introduced into any of the lymphatic vessels of the neck, in
the -horse or the large ruminants, the discharge of fluid in a
given time was increased one-quarter, one-third, and even
one-half, during movements of mastication.2

Increase in the flow of chyle in the thoracic duct, as the
result of compression of the abdominal organs, or by knead-
ing the abdomen with the hands, was observed by Magendie,3
and the fact has been confirmed in all recent experiments
on this subject. The same effect, though probably less in
degree, is produced by the peristaltic contractions of the
intestines.

When a tube is introduced into the upper part of the
thoracic duct, it is frequently the case that the fluid is dis-
charged more forcibly with each pulsation of the heart.

Paris, 1851, tome i., p. 208 ; and POGGENDORFF'S Annalen der Physick und Che-
mie, Leipzig, 1832, Bd. xxv., S. 517.)

1 See vol. i., p. 317 et seq., and page 325 cl seq., for the function of the
valves of the veins.

2 COLIX, Traite de Physiologie Comparee des Animaux Domestiques, Paris,
1856, torne ii., p. 89.

3 MAGENDIE, Precis tflementaire de Physiologie, Paris, 1836, tome ii., p.
183.

544: ABSORPTION.

This was frequently observed by Dalton in his experiments
on the thoracic duct, and he describes the jets as being
" like blood coming from a small artery when the circulation
is somewhat impeded." 1 This impulse is due to compression
of the thoracic duct as it passes under the arch of the
aorta. Its influence upon the general current of the
lymph and chyle is probably insignificant, but the fact
attracted the attention of Haller, who attached to it a
great deal more importance than it is now believed to

Influence of the Movements of Respiration. — While the
vis a tergo must be regarded as by far the most important
agent in the production of the lymphatic circulation, the
movements of fluids in the thoracic duct receive constant and
important aid from the respiratory acts. This fact has long
been recognized ; and in the works of Haller will be found a
full discussion of the influence of the diaphragm and the
movements of the thorax upon the circulation of chyle.3 The
observations of Colin on this subject are most valuable, as
he was the first to successfully establish a fistula into the
thoracic duct in large animals. He always' found a marked
remittency in the flow of chyle from a fistula into the tho-
racic duct, which was absolutely synchronous with the move-
ments of respiration. With each act of expiration, the fluid
was forcibly ejected, and with inspiration, the flow was very
much diminished or even arrested. These impulses became
much more marked when respiration was interfered with and
the efforts became violent. The intermittency of the cur-
rent was sometimes'so decided, that the pulsations were re-
peated in a long elastic tube attached to the canula for the

1 DALTON, Lectures on the Physiology of the Circulation. — American Medical
Monthly and New York Review y December, 1860, p. 416.

2 HALLER, Elementa Physiologies Corporis Humani, Bernss, 1765, tomus vii.,
p. 237.

3 Ibid.

INFLUENCE OF THE MOVEMENTS OF RESPIRATION. 545

purpose of collecting the fluid.1 These observations were con-
firmed by Dal ton, who noted the interesting fact, that in ani-
mals poisoned with woorara, in which artificial respiration
was continued by insufflation, the phenomena were reversed ;
the abundant discharge then took place with insufflation,
when the parts contained in the thorax were compressed by
the distended lungs, and in the intervals, the flow became
scanty or ceased.3

The amount of influence exerted by the respiratory move-
ments upon the flow of the lymph and chyle can be best ap-
preciated by examining carefully the mechanism of its oper-
ation.

With each act of inspiration, all the liquids, as well as
the air, are drawn toward the cavity of the thorax. In
this way, the thoracic duct is dilated and then becomes
most distended with fluid. At the same time, the flow of
lymph from the right lymphatic duct into the right subcla-
vian vein is increased. After the thoracic duct has been thus
dilated in inspiration, at the moment of expiration, in com-
mon with all the other parts contained within the thorax, it
undergoes compression ; the valves prevent the reflux of its
contents, and, as a necessary consequence, the fluid is then
discharged with increased force into 'the left subclavian. vein.
It can be readily understood how the act of inspiration, while
it has a tendency to fill the thoracic duct from below, op-
poses the discharge of fluid from a fistula.

From all these considerations, it is evident that, although
there are many circumstances capable of modifying the
currents in the lymphatic system, the regular flow of the
lymph and chyle depends chiefly upon the vis a tergo / but
the vessels themselves sometimes undergo contraction, and
they are subject to occasional compression from surround-
ing parts, which, from the existence of numerous valves in

1 COLIN, Traiie de Physiologic Comparee des Animaux Bomesiiques, Paris,
1856, tome ii., p. 90.

2 DALTON, op. cit., p. 416.

35

54:6 ABSORPTION.

the vessels, must favor the current toward the venous system.
The alternate dilatation and compression of the thoracic duct
with the acts of respiration is likewise an aid to the circula-
tion, and is more efficient than any other force, except the vis
a tergo. The action of the valves is precisely the same in
the lymphatic as in the venous syst.em.

D E X.

Absorbent system, discovery of, . . 422
Absorption, general considera-
tions, 415

by blood-vessels, 416

experiments on the action of

the blood-vessels in, '. . . . . 418

in the mouth, .420

of liquids and the products

of digestion in the stomach,.. .. 421

in the small intestine, 421

proof of, by demonstration

of albumen, glucose, etc., derived
from food, in the blood of the

portal system, 421

of secreted fluids with digest-
ed alimentary matters, 422

by lacteal and lymphatic ves-
sels, 422

of gases in the alimentary

canal, 422

from parts not connected

with the digestive system, 450

from the skin, 451

from the respiratory sur-
face, 455

from the closed cavities, .... 457

— — from subcutaneous areolar

tissue, 458

from reservoirs of glands, . . 458

from the urinary bladder,. . . 459

from the ducts and the paren-
chyma of glands, 459

of fats, mechanism of, 459

of mercury and particles of

carbon, 463

variations and modifications

of, 464

of woorara and venoms,. . . . 465

of liquids which disorganize

the tissues, 466

Absorption, influence of the condi-
tions of the blood and of the ves-
sels on, 466

influence of loss of blood on, 466

influence of repletion of the

vessels on, 467

influence of the nervous sys-
tem on, 467

Acid principle of the gastric juice, 238

Album Grsecum, 393

Albumen, 47

vegetable, 51

action of gastric juice upon, . 258

comparative digestibility of,

raw and coagulated, 259

Albumen-peptone, 260

Albuminoids, action of intestinal

juice upon, 328

absorption of, by lacteals,. . . 444

Albuminose, 263

interference of, with Trom-

mer's test for glucose, 264

Alcohol, 102

— — elimination of, 103

effects of, upon the nervous

system, 105

influence of, upon the exhala-
tion of carbonic acid,. 105

influence of, upon nutrition,.. 106

influence of, upon the capa-
city for enduring cold, 100

influence of, upon the capa-
city for labor, 110

Ale, 113

Aliment, definition of, 44

quantity and variety of neces-
sary to nutrition, 122

influence of, upon the capa-
city for labor, 127

necessity of vaiiety in, 128

548

INDEX.

Aliment, effects upon the system of

restriction to a single article, . . 130
Alimentary principles, nitrogen-

ized, 45

non-nitrogenized, 54

inorganic, 63

Alimentary substances, compound, 67
derived from the animal

kingdom, 69

preparation of those derived

from the animal kingdom, 86

derived from the vegetable

kingdom, 89

Alimentation, effects of insufficient

food in man, 34

Amandine, 52

Andersonville, condition of the

United States soldiers, prisoners

of war at, 37

Anus, 390

Appendix vermiformis, 385

Appendices epiploicas, 387

Appetite, 15

— — modifications of, by season

and temperature, 16

influence of exercise, etc.,

upon, 16

influence on, of extirpation of

the spleen or of one kidney,.. . . 17

Asparagus, 99

Azygos uvulas muscle, 185

Baking, in the preparation of

food,.. 88

Barley, 92

Beef, 70

composition of, 71

Beef-steaks, composition of, cook-
ed, 72

Beer,.. , 113

Beet-root, 99

Bicuspid teeth, 142

Bile, action of, in digestion, 360

experiment to ascertain quan-
tity of secreted, ' 364

excrementitious and recre-

mentitious properties of, 365

general physical properties

of, 366

reaction of, 366

peculiar salts of, 366

influence upon the formation

of chyle of ligating the common

bile-duct, 368

influence of, .upon peristaltic

movements of the intestine,. 371, 380

Bile, influence of, in preventing
putrefactive changes in the con-
tents of the intestine, 371

influence of, on the digestion

of fat, 372

influence of, in exciting con-
tractions of the intestinal villi, . 373

resorption of salts of, in the

intestine, 374

variations in flow of, with di-
gestion, 375

imbibition of the coloringmat-

ter of, by the walls of the gall-
bladder after death, 504

Biliary fistula, 361-368

observations on an animal

with, 369

Biliary matter, 366

Biliary resin, 366

Birds, flesh of, used as food, 75

Blood, as an article of food, 76

Boiling, in the preparation of food, 88

Bread, 92

mode of making, 93

made of gluten, 53

brown, . 95

unfermented, or aerated, ... 96

Broiling, in the preparation of food, 88

Brunn, gland's of, 313

Buccul glands, 166

Buckwheat, 91

Butter, 80

Buttermilk, , 79

Cabbage, 99

Csecum, , 384

Caffeine, 119

Cake, 96

Calf's head and feet, used as food, 76

Canine teeth, 142-143

Capillary attraction, 479-482

Carbon, comparison between the

quantity of, discharged and the

quantity ingested, 124

Carbon, penetration of particles of,

into the blood-vessels, 464

Carbonate of lime, action cf the

gastric juice upon, 270

Carrots, 99

Caseine, 48

vegetable, 51

action of the gastric juice

upon, 261

Caseine-peptone, 262 .

Cauliflower 99

Celerv,.. .... 99

INDEX.

549

PAGE

Cellulose, 60

Cement of the teeth, 140

Cereal grains,. . . 90

Cerealine, 95

Cheese, .. 81

composition of, .....„, 80

made of peas, 52

Chiccory, . ..." 99

adulteration of coffee with, . . 118

Chloride of sodium, 64

Chocolate, 120

preparation of, for use, 121

Cliolesterine, transformation of, in-
to stercorine, 402

presence of, in the faeces, iin-

. der certain conditions, and in the

meconium, 403

Choleic acid, 366

Cholic acid, 366

Chondrine, 48

Chyle, 529

general properties of,., .530, 531

quantity of, 532

.composition of, 533, 536

presence of sugar in, 537

— r— microscopical characters of, 537
Chyle and lymph, comparative

composition of, 536

presence of sugar in, 520

presence of urea in, 520

movements of, 538, 540

influence of the forces of en-

dosmosis and transudation en

the movements of, 540

influence of the. contractile

walls of the vessels on the

movements of, 542

influence of pressure from

surrounding parts on the move-
ments of, 543

influence of movements of

respiration on the movements

of, ; 544

Cider, ' 114

Clams, used as food, 84

Climate, influence of, upon the

diet, 128

Closed follicles of the stomach, ... 217

Cocoa, composition of, 121

Coffee, , 114

influence of, upon capacity

for labor, 114

influence of, upon capacity

for enduring cold, 116

composition of, 117

varieties of... ,.118

Coffee, adulteration of, with the

chiccory-root, 118

infusion of the leaves of,. . . 118

Colon, 384

muscular bands of, 388

Coloring matters, absorption of, by

the lacteals, 447

Condiments, 100

Corn, 90

Crabs, used as food,. 85

Cream, 79

Cresses, 99

Crustacea, used as food, 85

Defecation

sensations which precede the

act of, 406,

relaxation of the external

sphincter in,

action of the levdtor ani in,

muscular acts concerned in, .

influence of the nervous sys-
tem upon,

Deglutition,

physiological anatomy of the

parts concerned in,

mechanism of,

first period of,

second period of,

protection of the posterior

nares during the second period
of,

protection of the opening of

the larynx during the second
period of,

function of the epiglottis in

closure of the glottis in,. . .

importance of the sensibilit}

of the top of the larynx in, ...
itudy of, by auto-hryngo

scopy

third period of,

action of the oesophagus in,.

duration of the third period

of,

character of the movements

of,

in various positions of the

body,

of air,

Dentine,

Dialysis (note),

Diastase (note;,

animal,

Diet (see Aliment),

Diffusion of liquids,

40G

408

408
408
409

410

181

181
188
188
191

194
194
196

197

202
204
204

205
206

206

207
140

477
59

179
44

489

550

USTDEX.

Digestion, general considerations,. 133

duration of, 134

in the mouth, 135

in the stomach, 208

influence of exercise upon, . . 282

influence of loss of blood

upon, 283

influence of age upon,. 283

influence of the nervous sys-
tem upon, 283

in the small intestine, 308

Digestive apparatus, general ar-
rangement of, 133

Digestibility of different articles, . . 273

Drinks, 101

Drinking, mechanism of, 138

Duodenum, 309

Eggs, as articles of food, . .' 77

Electricity, influence of, in modi-
fying endosmsis, 499

Enamel of the teeth, 139

Endosmosis, 469, 471

discovery of laws of, 471

experiments on, anterior to

the observations of Dutrochet,. 472

experiments of . Dutrochet

upon, 474

conditions necessary to,. ... 476

behavior of albumen and al-

buminose in, 477

influence of membranes upon, 478

application of laws of capil-
lary attraction to, 478

through porous septa, 482

through homogeneous mem-
branes, 483, 485

through liquids, 485

production of, by the gal-
vanic current, 486

influence of different liquids

upon,... , 488

modifications of, due to the

extent and thickness of the

permeable membrane, 494

modifications of, due to pres-
sure and the density of liquids, .

494-497

modifications. of, due to move-
ments of liquids, 497

modifications of, due to tem-
perature, 499

modifications of, induced by

electricity, *. 499

application of physical laws

to, 501

PAOB

Endosmosis of fatty emulsions, . . . 502

of dense saline and other

. solutions,. 464, 503

modifications of, through the

nervous system, 505

Endosmotic equivalents, 490-494

Enemata, nutrition by (note),. . . . 390
Epiglottis, function of, in degluti-
tion, 194-198

effects of removal of, in the

human subject and the inferior

animals, 196,198,201

Eructation, 306

Excretion, 398

Excretoleic acid, 899

Faeces, general characters of, 394

quantity of, 395

proportion of solid matters

in, - 396

microscopical characters of,. 397

summary of the characters of, 403

time occupied in the passage

of, through the colon, 405

accumulation of, in the sig-

moid flexure, 408

expulsion of (see Defecation), 406

Fats, 61

proportion of, in certain ve-
getables, 62

composition of, 63

action of the gastric juice

upon, 267

action of the pancreatic

juice upon, 342

acidification of, by the pan-
creatic juice and the tissue of

the pancreas, 347

influence of the bile on the

digestion of, 372

absorption of, by the lacteals

and blood-vessels, 426

mechanism of absorption

of, ..459, 502

influence of the alkalinity of

the fluids upon the absorption

of, 461

penetration of, into the intes-
tinal epithelium, 402

Fatty diarrhoea, 348

Fauces, pillars of, 182

— r- isthmus of, 184

Fibrin, 48

vegetable, 51

action of the gastric juice

upon, 260

INDEX.

551

Fibrin-peptone, 261

Fishes, used as food, 82

Flavoring articles, 100

Food (see Aliment), 44

Frogs, used as food, 84

Fruits, 100

Frying, in the preparation of

food, 89

Game, 74-75

Garlics, 99

Gases found in the alimentary

canal, 410

origin of, in the intestine,. . 412

absorption of, in the intes-
tine, 422

Gasterase, 235

Gastric fistula in the inferior ani-
mals ; mode of operating, . . .221-222

case o-f Alexis St. Martin, ... 223

Gastric juice, 217

first obtained by causing

animals to swallow perforated
tubes filled with sponge, etc.,. . 218

mode of collecting from a

fistula, 222

secretion of, 225

action of acids and alkalies

upon secretion of, - 227

influence of gustatory im-
pressions upon the secretion

of, 227

conditions which disturb the

secretion of, 228

secretion of, in different parts

of the stomach, 229

quantity of, secreted in the

twenty -four hours, 230

composition of, 232

specific gravity of, 233

power of resisting decompo-
sition and antiseptic properties

of, , 234,267

chemical analysis of, in the

dot

234

organic principle of, 235

source of acidity of, 237

chlorohydropeptic acid in,. . 242

lactic acid in, 243

acid phosphate of lime in,. . 245

action of, upon carbonate of

lime, 248

— — principles upon which its

acidity depends, , 248

• ordinary saline constituents

of, 249

Gastric juice, digestive properties
of, depend on the presence of or-
ganic matter and a free acid, 251, 253

the normal acid of, may be

replaced by certain other acids, 252

mixture of mucus in, 254

action of, upon meats, ..... 255

actiojn of, upon albumen, raw

and coa'gulated, 258

action of, upon fibrin, 260

action of, upon caseine,. . . . 261

action of, upon gelatine, . 262

action of, upon vegetable ni-

trogenized matters, 262

action of, upon gluten, 262

catalytic action of 267

• action of, upon fats, 267

action of, upon saccharine

and amylaceous principles 268

action of, upon inorganic

principles, 270

action of, upon the coats of

the stomach, 275

influence of section of the

pneumogastric nerves upon se-
cretion of, 284

Gastric tubules, 213

Gelatine, 48

composition of, 49

influence of, upon nutrition, 50

Globulins in the lymph, 527

Glottis, closure of, in deglutition, . . 196
Glucose, absorption of, by the lac-
teals, 446

Gluten, 52

action of, as a ferment, 53

action of the gastric juice

upon, 262

Gluten-bread, 53

Glutine, 54

Glycine, 366

Glycocholic acid and glycocholate

of soda, 366

Goat's flesh, as an article of food, 73
Gum, 61

Hunger, 14-17

location of sense of, 18

nerves which convey the im-
pression of, to the brain, 20

Hydro-carbons, 54

Hydrochloric acid, question of the
existence of, in the gastric juice, 237

Ileo-cascal valve, 385

lleurn, 311

552

INDEX.

PAGE

Imbibition and endosmosis,. . .469-471

Inanition, 23

loss of weight in, 25

influence of age upon loss of

weight in, 26

proportionate loss in differ-
ent parts of the body in, 27

influence of, upon the blood

and the circulation, 28

influence of, upon respiration, 29

influence of, upon the animal

temperature, 29

influence of, upon the ner-
vous system, 31

duration of life in, 31

. influence of age upon dura-
tion of life in, 15

Incisor teeth, 142

Inorganic salts, absorption of, by

the lacteals, 446

Insalivation, 155

Intestine, length of, 134

Intestine, small, general view of ar-
rangement of, 137

physiological anatomy of, ... 308

dimensions of, 309

divisions of, 309

mucous membrane of, 311

o-landular structures of, 313

vim of, 815

solitary glands and patches of

Peyer in, 319

"movements of, 376, 378, 380

causes of movements of,. 378, 380

uses of gases in, 379

influence of the nervous sys-
tem upon the movements of, ... 381

composition of gases of,. ... 411

absorption in, 421

Intestine, large, physiological anat-
omy of,. 383

peritoneal coat of, 386

muscular coat of, 387

mucous membrane of, 389

ordinary follicles of, 389

utricular glands of, 389

closed follicles of, 389

secretion of the mucous mem-
brane of, 390

changes of the alimentary

residue in, 391

contents of, 393

movements of, 404

gases of, 412

Intestinal fistula, case of, in the

human subject, 325 i

Intestinal juice, 322

— T— mode of collecting, 322

quantity of, 326

reaction of, 327

proportion of solid matters in, 327

glandular organs concerned

in the production of, 327

composition of, in the horse, 327

action of, in digestion, 327

action of, upon starch, 328

want of action of, upon cane-
sugar, 328

want of action of, upon fats, 328

action of, upon albuminoids, 328

Inuline, 60

Iron, 65

Jejunum, 311

Lacteals, 435

origin of, in the intestinal

villi, 317

discovery of,. ... 423

Lactic acid, presence of, in the gas-
tric juice, 243

Legumine, 62

Leguminous ' roots, leaves, seeds,

etc., 97

Leucocytes in the lymph, 522

development of, in the lymph

and in a clear blastema,. . . 523-527

Levator palati muscle, 185

Levator ani, action of, ia defeca-
tion, 408

Lichenine, 60

Lieberkiihn, follicles of, 314

Lime, acid phosphate of, in the gas-
tric juice, 245

Lingual glands, 166

Liquors, distilled, „ 110

malt, 113

Lobsters, used as food, 85

Lymph, 503

mode of obtaining 503

quantity of, 510

general properties of,. .. .511-513

coloration of, after discharge

from the vessels, 512

presence of red blood-corpus-
cles in, 512

• coagulation of, 513

composition of, 514-521

presence of sugar in,. . ..520, 537

presence of urea in, 520, 523

effects of abstinence upon

the constitution of, .. . 521

INDEX.

553

Lymph, differences in the composi-
tion of, in different vessels, 522

corpuscular elements of, .... 522

origin of,.. 527

function of, 528

Lymph and chyle, comparative

composition of, 536

movements of, 538-540

influence of the forces of en-

dosmosis and of transudation

on the movements of, 540

influence of the contractile

walls of the vessels on the

movements of, 542

influence of pressure from

surrounding parts on the move-
ments of, 543

influence of the movements

of respiration on the move-
ments of, 544

Lymphatics, discovery of, 425

physiological anatomy of, ... 427

mode of injection of, in the

skin, 427

relation of the plexus of ori-
gin of, to the blood-vessels,. . . . 429
diameter of vessels of ori-
gin of, 429

superficial layer of, 430

deep layer of, 430

valves of, 431, 438

slight variation of size of, in

their course, 431

peculiarities of, in the brain

and spinal cord, 432, 433

of the mucous system, 432

of the serous membranes,. . . 433

of the muscular system, .... 433

of the respiratory system,. .. 433

of the glandular system, .... 433

situations in which they have

not been demonstrated, 434

course of, 435

structureof,. 436

connections of, with sur-
rounding tissues, 437

elasticity and contractility

of, -... 439

Lymphatic glands, number and sit-
uation of, 439

structure of, 440

course of ve-ssels through, . . 440

follicles of, 441

arrangement of the lymphat-
ics in the interior of, 442

blood-vessels of, 443

Lymphatic glands, nerves of,. .... 443

function of 444

Lymph-corpuscles, 522

function of, 527

Macaroni, 97

Malt-liquors, 113

Mannite, 61

Mastication, 133

physiological anatomy of

parts concerned in, 139

muscles of, 146

action in, of muscles which

depress the lower jaw, 147

action in, of muscles which

elevate the lower jaw and move
it laterally and antero-poste-
riorly, .

149

action of the tongue, lips, and

cheeks in, 150

summary of the process of, . 153

influence of, upon the parotid

secretion, 160

Maxillary bone, superior, 144

inferior 144

articulation of, with the tem-
poral bone, 145

Meats, 69

from non-domesticated ani-
mals, 74

from animals killed before

maturity, 74

action of gastric juice upon, . 255

Mercury, absorption of, 464

Merycismus (see Rumination), .... 295

Milk, as an article of food, 76

composition of, 77

Molar glands, 166

Molar teeth, 142, 143

Mollusks, used as food, 84

Mucilages, 61

Mucous follicles of the stomach,. . 214
Mucus, mixture of, in the gastric

juice, 254

Musculine, 40

Mussels used as food, 84

Nitrogen, comparison between
quantity of, discharged and in-
gested, 124

Nitrogenized alimentary principles, 45
Non-nitrogenized alimentary prin-
ciples, 54

Oatmeal, 91

(Esophagus, general description of, 186

554:

INDEX.

(Esophagus, muscular fibres of, ... 187

mucous membrane of, 188

action of, in deglutition,. . . . 204

intermittent contractions of

the lower third of, 204

action of, in vomiting, 303

Oils (we Fats), 61

Onions, 99

Osmazome, 87

Oysters, used as food, 84

Palate, muscles of, 185

Pancreas, physiological anatomy

of, ". 330

situation of duct of, in the

rabbit, 345

effects of destruction of,. ... 347

cases of disorganization of,

in the human subject, 348

summary of functions of, ... 357

Pancreatic juice, mode of obtain-
ing the pure secretion, 332

secretion of, 336

composition of, 338

quantity of, 340

decomposition of, 340

reaction of, Avith chlorine,.. . 341

action of, in digestion, 341

— action of, upon fats,. . .< .342-350

action, of, upon starch, 350

action of, upon sugar, 353

action of, upon nitrogenized

principles, 354

Pancreatine, 339

Panification, 94

Parotid gland (see Saliva), 156

Parsnips, 99

Pectine,, 60

Pectose, 60

Pepsin, 235

mode of extraction of, 236

Peptic glands, 213

Peptones, 263

Peristaltic movements, influence

of the bile upon, 371, 380

of the small intestine (see

Small intestine), 376

Perry, 114

Peyerian patches, anatomy of,.. . . 319

secretion from, 324

Pharynx, general description of,.. 182

muscles of, 184

• mucous membrane of, 185

Pharyngeal glands, 167

Phosphate of lime, 65

action of gastric juice upon, . 270

PAGV

Picromel, 366

Pig's feet used as food, 76

Pleural cavity, absorption from, . . 457
Pneumogastric nerve, influence of
section of, upon stomach-diges-
tion, , 284

Poisons, absorption of, by the lac-
teals, 447

Pork, 73

Porter, 113

Potato, 98

composition of, 98

sweet, 98

Prehension of solids and liquids, 137

Ptyaline, 171

action of, upon starch, 171

Pulp-cavity of the teeth, 142

Pyloric muscle, 210

Ration of the United States sol-
dier, 127

of the British soldier, 126

Receptaculum chyli, discovery of, -425

Rectum, muscular fibres of, 387

mucous membrane of, 390

Regurgitation from the stom-
ach, 292

Reptiles used as food, 83

Respiratory surface, absorption

from,..! 455

Rice, 92

Roasting, in the preparation of

food, 88

Rumination, 292

course of the food in,. 293

in the human subject, 295

Eye, 91

Saliva, 155

functions of, 174

action of, upon starch, 174

action of the pure secretion

from the different glands upon

starch, 175

mechanical functions of, .... ISO

secretions from the smaller

glands of the mouth, tongue,

and pharynx, 166

Saliva, mixed, 167

excitation of secretion of, ... 168

quantity of, 169

general properties of, 170

composition of, 171

reaction of, with the perchlo-

ride of iron, 172

Saliva, parotid, 156

DsDEX.

555

Saliva, parotid, mode of obtaining
the pure secretion from the hu-
man subject, 157

composition of, in the human

subject, 157

comparison of, with the mixed

saliva, in the human subject,. . 158

organic principle of, 159

sulpho-cyanide in, , 159

influence of mastication upon

the secretion of, 160

alternation in the secretion

of, on the two sides, 160

influence of gustatory impres-
sions upon the secretion of,. . . . 161

functions of, 162

Saliva, sublingual, 164

general properties of, 165

secretion of, 165

Saliva, submaxillary, 162

composition and properties

of, 163

influence of gustatory im-
pressions upon the secretion of, 164

Salsify, '. 99

Sauerkraut, 99

Scallops, used as food. 84

Shrimps, used as food, 85

Skin, absorption from, 451

transudation from, in a bath, 454

Snails, used as food, 84

Solitary glands of the intestine, ... 319

Soup, formula for making, 87

Sphincter, internal, 389

external, 390

of O'Beirne, 407

Starch, 56

properties of, in different

vegetables, 56

granules of, 58

tests for, 58

changes of, into dextrine and

glucose, 59

principles resembling, 60

action of the saliva'upon, . . 174

action of the gastric juice

upon, 269

action of the intestinal juice

upon, 328

— — action of the pancreatic juice

upon, 350

summary of the process of

digestion of, 352

Stercorine, 399

extraction of, 399

crystals of, 400

PAGE

Stercorine, formation of, from

cholesterine, 402

Stewing, in the preparation df

food, 88

St. Martin, case of, 223

Stomach, physiological anatomy of,

135, 208

movements of, 136, 287

muscular coat of, 209

mucous membrane of, 21 2

glandular apparatus of, 212

character of the glands in dif-
ferent parts of, 2J2, 214

fistula into, 220

mucous follicles of, 214

closed follicles of, 2J7

duration of digestion in,. ... 271

immunity of, from digestion

by the gastric juice during life, 275

existence of living animals in, 277

digestion of parts of living

animals in, 277

protection of walls of, from

digestion during life, by the al-
kalinity of the blood, . ." 279

protection of walls of, from

digestion during life, by the cat-
alytic processes of nutrition, . . . 281

influence of section of the

pneumogastric nerves upon the

movements of, 285

— *- diiference between the mus-
cular contractions of, in the car-
diac and in the pyloric portion, 290

regurgitation from, 292

— — anatomy of, in ruminating

animals (note), 293

gases of, 411

absorption from, 421

Stomach-glands, 213

Stomach-tubes, muscular fibres
surrounding extremities of,. ... 217

Stylo-pharyngeus muscle, 184

Sublingual gland (see Sublingual

saliva), ; 164

Submaxillary gland (see Submax-
illary saliva), 162

Sugar, 55

action of gastric juice upon, 268

action of pancreatic juice

upon, 353

presence of, in the lymph

and chyle, 520, 537

Sulpho-cyanide in the parotid sali-
va, 159

in the mixed saliva, 1 72

556

EST3EX.

Sweet-breads,,

PAGE

. 76

Tao-foo, 52

Taurine, 366

Taurocholic acid, 366

Taurocholate of soda, 367

Tea, 118

composition of, 119

varieties of, 120

preparation of, for use, 120

Teeth, physiological anatomy of,...

139, 142

enamel of, 139

dentine, 140

cement, ^ 141

pulp-cavity of, ". 142

uses of Sensibility of, in mas-
tication, 152

Temperature, influence of, upon

endosmosis, 499

Tenesmus, 408

Tensor palati muscle, 185

Terrapins, used as food, 83

Theine, 119

Thirst, 21

location of sensation of, .... 22

relief of, by immersion of the

body in water, 454

Thoracic duct, discovery of, 422

anatomy of, 435

effects of obliteration of, 448

fistula into, 508

quantity of fluid obtained

from a fistula into, 509

Tongue, action of, in drinking, ... 137

action of, in mastication,. . . 151

action of, in deglutition,. . . . 189

Tonsils, 167

Transudation, 505

influence of pressure in the

blood-vessels upon, 506

influence of the constitution

of the blood upon, 508

Trichina spiralis, 73

Tripe, 76

Turtles, used as food, 83

IJrea, presence of, in the lymph

and chyle, 520, 528

Uvula, 185'

Valves of the lymphatics, . . .431, 438

Valvulre conniventes, 311

Velum pendulum palati, 182

Venison 74

Venoms, absorption of, 465

Vermicelli, 97

Villi of the small intestine, 315

contractions of, 316

lacteal vessels of, I .. 317

Viscera, animal, used as food, .... 76

passive condition of the stom-
ach in 298

action of the diaphragm and

the abdominal muscles in,. . 299,

from a pig's bladder substitu-
ted for the stomach in a living
animal,

by a girl after destruction of

the stomach by a corrosive poi-
son,

impossibility of, in a case in

which the stomach was extruded
by a wound in the abdomen, . .
action of the oesophagus in, .

305

299

301

302
303

summary of the act of, 304

protection of the glottis and

the posterior nares in, 305

ways in which it may be in-
duced, 305

Water, 64, 101

quantity of, necessary to nu-
trition, 124

absorption of, by the lacte-

als, " 446

Wheat, 90

Wines, Ill

constituents of, 112

sparkling, 112

of the United States, 113

Woorara, absorption of, 465

D. APPLET ON. & CO: S PUBLICATIONS.

A NEW BOOK BY LOUIS FIGUZER.

THE VEGETABLE WORLD;

BEING

A HISTORY OF PLANTS,

WITH THEIR BOTANICAL DESCRIPTIONS AND PECULIAR PROPERTIES.
BY LOUIS FIGUIER,

AtTTHOE OF "THE WOELD BEFOEE THE DELUGE."

Illustrated with Four Hundred and Forty-six Engravings interspersed through the
text, and Twenty-four full-page Illustrations,

Chiefly 3)rawn from Nature, by M. JFA. G U^T,

ILLOSTBATOK TO THE BOTANICAL COURSE OF THE FACPLT5T OF SCIENCES OF PAEI8.

One vol., '8 vo, beautifully printed. 584 pages. Cloth, $6.00; Half Calf,
$8.50; Full Calf, $10.50.

"The present volume maybe considered as the second contribution which M. Figuier has
made toward his Tableau de la Nature. ' The World before the Deluge1 contemplates a period
in the earth's history when its natural ornament was absent; when its surface was an arid desert
a vast solitude, the abode of silence and death. Plants preceded animals in the order of creation ;
when the great animals which preceded men were create* by the wisdom of the Eternal, the
earth was already clothed in a mantle of vegetation. * * * * The History of Plants
which is now submitted to the reader is divided into four parts: — I. The Organography and Phys-
iology of Plants. II. The Classification of Plants. III. The Natural Families of Plants. IV
The Geographical Distribution of Plan ia.""— Extract from Prtfa.ce.

"A volume which furnishes reading of the most attractive, fascinating, and profitable kind,
teaching the old many facts far from familiar to them, and leading the young into fields which
the study of a lifetime cannot exhaust. It reads as though it might have been originally written
in English, and it certainly contains more information upon the subject of which it treats than
any other single volume extant ; and this is imparted in so agreeable a manner that the work
deserves to be called popular in the best sense of the term. It is impossible to award too high
praise to the engravings which illustrate and ornament the work. They are executed in the best
style."— N. T. Times.

13. J±. <Sc Co. liave lately published,

The World Before the Deluge. By Louis Figuier. A New Edition,

Illustrated. 1 vol., 8vo. Cloth, $6 ; half calf, $8.50.
The Harmonies of Nature. By Dr. G. Hartwig. Illustrated. 1 vol.

8vo. Cloth, $7.50.
The Harvest of the Sea. By James G. Bertram. Illustrated. 1 vol., 8vo

Cloth, $7.50.

D. APPLET ON & CO'S. PUBLICATIONS.

-AJXTID EISTL-A-T^OEID E3DITIO3ST.

THE WORLD BEFORE THE DELUGE.

BY LOUIS FIGUIER.

The Geological Portion carefully Revised, and much Original Matter added,
BY HENRY W. BEISTOW, F. E. S., OF THE GEOLOGICAL SURVEY OF GREAT BRITAIN.

Containing thirty-four full-page Illustrations of Extinct Animals and Ideat, Landscapes of

the Ancient World, designed ~by Riou, and two hundred and two Figures of

Animals, Plants, and other Fossil Remains and Restorations.

lvol.,8vo. 437 pages. Beautifully printed. Cloth, $6.00.

" The text of this, the second edition of M. Figuier's popular work, has undergone a careful
revision, so as to assimilate the phraseology of the French geologist to that adopted in English
Science, as far as this could be accomplished without prejudice to the author's method and
reasoning. Some inaccuracies which had crept into the previous version have been rectified, and
statements or fact upon which discoveries subsequent to the publication of the original work
have thrown light, have been corrected or remodelled, so as to represent more precisely the
present state of scientific opinion."— Extract from Preface.

"This work is written in the most entertaining manner. It unfolds the history of the worl J
as shown in geoiogy, from its supposed gaseous state until the era of the Noachian deluge. To
the student of geology and the general reader, M. Figuier's work will prove very full of interest
* * * It is a good book, and good books are the need of the day.1'— New York Commercial
Advertiser. . >

3D. J±. &c CO. have lately published,

The Harmonies of Nature; or, THE UNITY OF CREATION. By Dr. G.
Hartwig, author of "The Sea and its Living Wonders," and "The Tropical
World." With eight full-page drawings, and nearly two hundred Woodcuts. 1
vol., 8vo, 406 pages. Cloth, $7.50 ; half calf, extra, $10 ; full calf, extra, $12.

The Harvest of the Sea. A Contribution to the Natural and Economic His-
tory of the British Food Fishes. By James G. Bertram. With fifty Illustra-
tions. 1 large vol., 8vo. 520 pages. Cloth, $7.50 ; half calf, extra, $10 ; full
calf, extra, $12.

Homes Without Hands : Being an Account of the Habitations Constructed
by various Animals, classed according to their principles of Construction. By
Rev. J. G. Wood, M. A. F. L. S., author of the " Illustrated Natural History,"
&c. With very numerous Illustrations, engraved on wood by G. Pearson, from
original drawings made by F. W. Keyl and E. A. Smith, under the author's
superintendence, expressly for this work. 1 vol., 8vo. Cloth, $7.50 ; half calf,
extra, $10 ; full calf, extra, $12.

THE ONLY COMPLETE AUD UNIFOKM EDITION,

LORD MACAULAY'S WORKS,

EDITED BY HIS SISTER,
L-A.IDY

8 Vola., large 8vo. Price, cloth, $40.00 ; half calf extra, $56.00 ; full calf

extra, $64.00. Beautifully printed in large clear type, on

thick toned paper, with a fine portrait engraved

on steel by W. Holl.

In preparing for publication a complete and uniform edition of Lord Macaulay's
Works, it has been thought right to include some portion of what he placed on record
as a jurist in the East. The papers selected are the Introductory Report on the
Indian Penal Code, and the notes appended to that code, in which most of its leading
provisions were explained and defended. These papers were entirely written by Lord
Macaulay, but the substance of them was the result of the joint deliberations of the
Indian Law Commission, of which he was President. They are by no means merely
of Indian interest, for while they were the commencement of a new system of law for
India, they relate chiefly to general principles of jurisprudence, which are of universal
application.

The contents are arranged in this edition as follows : Vols. I. to IV., History of
England since the Accession of James the Second ; Vols. V., VI., and VII., Critical
and Historical Essays, Biographies, Report and Notes on the Indian Penal Code, and
contributions to Knight's Quarterly Magazine ; Vol. VIII., Speeches, Lays of Ancient
Uome, and Miscellaneous Poems.

This last division of the work is completed by the insertion of the Cavalier's Song
and the Poetical Valentine to the Hon. Mary C. Stanhope, two pieces which were not
included in previous editions of Lord Macaulay's miscellaneous writings.

" Every admirer of Lord Macaulay's writings (and their name as legion) will
heartily thank Appleton & Co. for having produced this elegant edition of his
works. It seems almost idle to say any thing in praise of the great historian to
the American reader, but we cannot forbear expressing our admiration of the physical

as well as mental strength so manifest in his diction and style But it is not our

intention to write a critique on the man whose memory holds so prominent a place
in the heart of the reading world. The volumes before us should fill a niche in every
public and private library in our land." — Glen Falls Journal.

" His writings and his speeches, arranged in chronological order, exhibit the devel-
opments of a mind always more or less powerful, and announce the extent of his
reading and the tenacity of his memory. His contributions to the History of British
India show how usefully his time was spent during his sojourn at Calcutta."

D Appleton & Co.'s Descriptive Catalogue may be had gratuitously on
application.

D. APPLETON & CO.,

PUBLISHERS, BOOKSELLERS, & STATIONERS,

9O, 92 & 94 Grand Street, New York.

1). APPLET ON & CO:S PUBLICATIONS.

THE PHYSIOLOG-Y

AND

PATHOLOGY OF THE MIND.

By ELEISTRY lyt^TJDSIL.EY, M. D., London.
1 volume, 8vo. Cloth. Price, $4.00.

CONTENTS :

Fart I.— The Fiay§iology of tlie mind.

CHAPTER 1. On the Method of the Study of the Mind.
" 2. The Mind and the Nervous System.

" 3. The Spinal Cord, or Tertiary Nervous Centres ; or, Nervous Centres of Eeflex Action.
" 4. Secondary Nervous Centres ; or Sensory Ganglia; Sensorium Commune.
" 5. Hemispherical Ganglia; Cortical Cells of the Cerebral Hemispheres: Ideational

Nervous Centres ; Primary Nervous Centres; Intellectorium Commune.
" 6. The Emotions.
" 7. 'Volition.

" 8. Motor Nervo-us Centres, or Motorium Commune and Actuation or Effection.
• " 9. Memory and Imagination.

Part II.— Tlie Fatb©I®gy of the Mind.

CHAPTER 1. On the Causes of Insanity.
" 2. On the Insanity of Early Life.
" 3. On the Varieties of Insanity.

CHAPTER 4. On the Pathology of Insanity.
" 5. On the Diagnosis of Insanity.
" 6. On the Prognosis of Insanity.

CHAPTER 7. On the Treatment of Insanity.

" The first part of this work may be considered as embodying the most advanced
expression of the new school in physiological psychology, which has arisen in
Europe, and of which Bain, Spencer, Leycoch, and Carpenter, are the more eminent
English representatives." — Home Journal.

" The author has professionally studied all the varieties of insanity, and the
seven chapters he devotes to the subject are invaluable to the physician, and full of
important suggestions to the metaphysician." — Boston Transcript.

" In the recital of the causes of insanity, as found in peculiarities of civilization, of
religion, of age, sex, condition, and particularly in the engrossing pursuit of wealth,
this calm, scientific work has the solemnity of a hundred sermons ; and after going
down into this exploration of the mysteries of our being, we shall come up into
active life again chastened, thoughtful, and feeling, perhaps, as we never felt before,
how fearfully and wonderfully we are made." — Evening Gazette.

UNIVERSITY OF CALIFORNIA

Medical Center Library

THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW

Books not returned on time are subject to fines according to the Library
Lending Code.

Books not in demand may be renewed if application is made before
expiration of loan period.

JUN 3 -

10?n-l,'57(C4267s4)4128