Diseases of the stomach

Front matter

Bonk . U< 3

(V^rifoN MM

COPYRIGHT DEPOSIT.

Preface To The Fifth Edition

While the plan of the book has remained the same, the text has been thoroughly revised and several additions made. Radiography has made rapid strides and has contributed largely toward clearing the field of diagnosis. It has accordingly been given a more prominent place. It gives me great pleasure to notice the widespread interest the American medical profession is of late years taking in the Diseases of the digestive tract. That my work has been a contributing factor thereto and of some assistance to my worthy Colleagues affords me great satisfaction.

Max Einhorn.

New York, June 10th, 1911.

Preface To The First Edition

During the last twenty years our views in the field of diseases of the stomach have undergone great changes. W. Beaumont in this country laid the corner-stone of scientific research and experimental study on the functions of this organ in 1825. From that time on the science of gastric diseases remained in a state of quiescence until 1867, when Kussmaul methodically applied the stomach pump in the treatment of dilatation of the stomach. The real progress, however, began a few years later, when Leube made use of the stomach pump for diagnostic purposes. Ewald, Boas, Reichmann, Riegel, and others then instituted extensive studies of the gastric functions in health and disease. This second epoch in the study of digestive diseases, which had its inception in Germany, soon made itself felt in other countries, notably France, Russia, Austria, England and America. In our country especially it seems that a very fruitful activity is developing in this direction. Among the older writers I would mention the names of Austin Flint, Delafield, Pepper, and Osier, all of whom contributed largely to our clinical knowledge in this branch of medicine. The newer researches were taken up here and further advanced by Charles G. Stockton, Francis P. Kinnicutt, Allen A. Jones, D. D. Stewart, J. C. Hemmeter, and many other very active investigators. The progress achieved relates to a more profound knowledge of gastric affections — by examination of the functions — and to a more successful therapy, first by diet, secondly by the newer mechanical means of treatment (lavage, spray, electricity), and thirdly by surgical orocedures. Our

vii

Viil PREFACE.

more extensive knowledge of diet and treatment is of advantage not only to the specialist, but to the general practitioner as well, and it is with the view of assisting the latter in the acquisition of all these advantages which have accrued that this treatise has been written. A series of articles on Diseases of the Stomach, which I contributed to the "Twentieth Century- Practice of Medicine" has greatly facilitated my work. In this book the subject has been considered from a more practical standpoint, and special attention has been paid to diet and treatment. I trust that this work will aid in awakening a deeper interest in the study of diseases of the stomach among American physicians, and if this object be realized, I shall feel more than recompensed for the time spent in its preparation^

Max Einhorn.

New York, June loth, 1896.

CHAPTER I. Anatomy and Physiology

Anatomy, 1

Situation, 2

Blood-vessels, 2

Relations of the Stomach to Xeighboring Organs, 3

Structure of the Stomach, 3

Blood-vessels, Lymphatics, and Nerves of the Stomach, 6

Physiology 7

The Gastric Juice, 9

Gastric Digestion, 11

Intestinal Digestion, 14

CHAPTER II. Methods of Examination

Interrogation of the Patient, 17

Methods of Physical Examination, 20

Inspection, 20

Palpation, 22

Percussion, 24

Auscultatory Percussion, 26

Sounds of the Stomach, 26

Splashing Sound (Clapotage), 26

Deglutition Sounds, 27

Dripping Sounds, 28

Bubbling Sounds, 28

Succussion Sounds, 28

Gurgling Sounds, 29

Respiratory Sounds, 29

Sizzling Sounds, 29

Ringing Sound- 30

<TNopha£oscopy, 30

Ga-troscopy, 33

Ga-trodiaphany or Transillumination of the Stomach, 36

Roentgen Rays 40

Radium Transillumination of the Stomach, 48

ix i CONTENTS.

Radium Photographs of the Stomach 50

Examination of the Functions of the Stomach 53

Secretory Function 53

Leube-Reigel's Test Dinner, 55

Test Breakfast of Ewald and Boas 56

Germain See's Test Meal, 56

Klemperer's Test Meal 57

Ewald-Boas' Expression Method, 58

Contraindications to the Use of the Stomach Tube, 78

Other Methods of Testing the Gastric Secretion, 78

Exact Determination of the Quantity of Chyme within the

Stomach 89

Abnormal Constituents of the Gastric Contents, 90

Microscopical Examination of the Gastric Contents, 97

Value and Limitations of Examinations of the Gastric

Contents 113

Absorptive Function of the Stomach, 115

Motor Function of the Stomach, 116

Mechanical Function, 119

CHAPTER III. Diet

Dietetics, 127

Composition of the Most Common Food Substances, 129

Animal Foods 133

.Me Foods, 135

Liquid Foods, 136

Utilization of Food, 137

Diet in Health 137

A Few Hints with Regard to the Proper Way of Eating, 137

Dietetics in Diseases of the Stomach, 139

In Acute Diseases of the Stomach 143

In Chronic Affections of the Stomach, 145

CHAPTER IV. Local Treatment of the Stomach

Lavage 155

The Gastric Douche 160

The Gastric Spray 164

The Stomach Powder Blower , 166

Electricity 168

[n8tniments, Apparatus, and Chemicals Required, 180

COXTEXTS. xi

CHAPTER V. Organic Diseases with Constant Lesions

The Acute and Chronic Gastric Catarrh 182

Acute Gastritis 182

Gastritis Acuta Simplex or Acute Gastric Catarrh 1S2

Etiology, 1S2

Symptomatology 1S4

Diagnosis 1S5

Prognosis 1S6

Treatment 1S6

Gastritis Phlegmonosa 1S7

Diagnosis 1S9

Treatment 1S9

Gastritis Toxica 189

Chronic Gastric Catarrh — Gastritis Glandularis Chronica 191

Pathological Anatomy 191

Procrno^is 201

CHAPTER VI. Organic Disease^ with Constant Lesions — Continued

- ■ latioo of the Ulcer 224

- :iptomatology 226 arii CONTENTS.

Ulcer of the Stomach, Duration of the Disease, 234

Perforation, 234

Localization of the Ulcer, 242

Diet in Gastric Ulcer, 247

Exulceratio Simplex (Dieulafoy), 258

Surgical Procedures, 262

CHAPTER VIII. Organic Diseases with Constant Lesions — Continued

Cancer' of the Stomach (Carcinoma Ventriculi), 276

Parasitic Theory, 281

Topographical Relations, 284

The Shape of the Stomach, 285

Secondary Changes Accompanying Cancer of the Stomach, . . . 286

Cancerous Metastases, 286

Duration and Prognosis, 309

CONTEXTS. xiii

Cancer of the Stomach. Treatment 309

Surgical 309

Medical. 312

Radium, 312

CHAPTER XIII. Nervous Affections of the Stomach

Sensory Gastric Neuroses, 421

(a) Abnormal Sensations of a General Character, 422

Bulimia, 423

CONTENTS. xv

Parorexia (Perversion of Appetite), 425

Polyphagia, 426

Akoria, 426

Nervous Anorexia, 426

Inanition, 431

(6) Special Sensations within the Stomach Itself, 436

Gastric Idiosyncrasies, : 437

Abnormal Sensations, 439

Hyperesthesia of the Stomach 439

Gastralgokenosis, 450

Motor Neuroses, 450

Spasm of the Cardia (Cardiospasmus), 450

Eructation, 466

Pyrosis, 468

Regurgitation, 468

Duration, 472

Nervous Vomiting (Vomitus Nervosus), 477

Juvenile Vomiting, . 479

Periodic Vomiting, 479 xvi CONTENTS.

Reflex Vomiting 481

Idiopathic Nervous Vomiting, 482

Pneumatosis, 483

Hypanakinesis Ventriculi 484

Hyperanakinesis Ventriculi, 484

Peristaltic Restlessness of the Stomach, 484

Antiperistaltic Restlessness of the Stomach, 486

Incontinentia Pylori (Incontinence of the Pylorus), 486

Pylorospasmus, 488

Atony of the Stomach 492

Secretory Neuroses, 494

Nervous Dyspepsia 495

Chapter XIV

The Condition of the Stomach in Diseases of Other Organs.

Tuberculosis of the Lungs, 502

Syphilis of the Stomach 505

Chlorosis and Anaemia, 509

Heart Lesions, 509

Dyspeptic Asthma, 510

Disturbances of the Liver, 513

Diseases of the Kidney, 513

Diabetes, 514

Arthritis Deformans, 514

Gout, 514

Malaria, 514

Diseases of the Skin, 515

Pemphigus of the Mouth, 515

Urticaria and Erythema, 515

Eczema, 516

Acne Simplex and Acne Rosacea, 516

Psoriasis, 516

DISEASES OF THE STOMACH.

Chapter I. Anatomy And Physiology

Anatomy.

The stomach is a pyriform sac the longitudinal diameter of which is as a rule oblique in position. The larger part of the ors;an is situated higher up and more to the left than the smaller,

Fta. 1. — The Stomach. C, cardia; P, pylorus; F, fundus; G, greater curvature; L, lesser curvature.

which is directed to the right somewhat upward and sometimes backward. This smaller extremity terminates in the small intestine. The point at which the stomach communicates with the small intestine is called pylorus (P) and is recognizable on its outer surface by a furrow and on its inner surface by a protruding fold (valvula pylori). The communication between the (esophagus and the stomach is called the cardia (C) and issituated at the upper part. A straight line (AB) drawn in the direction of the oesophagus and prolonged through' the stomach would cut off one-fourth or one-fifth of this organ to the left. This portion to the left is called the greater cul-de-sac (saccus csecus) (F) or fundus. The volume of the stomach varies according to the condition of its contents. When filled its long diameter measures 26 to 31 cm., the transverse diameter being 8 to 10 cm. at the fundus and much less at the pylorus. Here it measures about 2.6 cm. When the stomach is filled the anterior wall turns somewhat upward and the posterior downward (a rotation of the organ takes place).

Situation.

The stomach lies on the left side of the body, and only one-sixth of it is situated on the right side. This includes thepylorus and the adjacent parts which lie behind the liver (lobus Spigelii) . The cardia is situated in the left parasternal line, somewhat above the ensiform process; the lesser curvature lies on the left side, close to the vertebral column and runs downward and parallel with it. The greater curvature extends from the base of the gall bladder and the liver into the left hypochondriac region in which the whole of the fundus is found.

Blood-Vessels.

The blood-vessels enter the stomach at its upper and lower borders and thus divide the surface of the stomach into two equal parts. These lines mark the superior and inferior margins of the stomach, the upper and lower curvature, or the lesser and greater curvature.

STRUCTURE OF THE STOMACH. 3

The Relations of the Stomach to Neighboring Organs.

The left segment of the stomach is in contact with the diaphragm above, and to the left with the spleen and the left kidney. The lesser curvature and the adjacent part of the organ are in relation with the pancreas, and the splenic artery and vein. The greater curvature and a portion of the front wall as well as the pylorus touch the liver and also the transverse colon.

Structure of the Stomach.

The stomach has four coats, the serous, muscular, areolar or submucous, and mucous. The serous coat is derived from the peritoneum and forms a thin, smooth, transparent and elastic membrane. It closely covers the entire viscus excepting along it> two curvatures. Here the attachment is looser, leaving space for the larger blood-vessels.

The muscular coat is composed of plain muscular tissue, forming three sets of fibres disposed in layers — namely, the longitudinal, the circular, and oblique fibres. The outermost layer is the longitudinal one, then follows the circular, and the innermost is the oblique. The latter is very incomplete, and is a continuation of the circular fibres of the gullet. These fibres descend obliquely from the cardiac orifice upon the anterior and posterior surfaces of the stomach, and after spreading out from one another, they run in the direction of the circular fibres and terminate at the greater curvature.

The submucous coat connects the muscular and mucous coats and consists of areolar tissue. It is the seat of division and passage of the blood-vessels.

The mucous membrane is a smooth, soft, rather pulpy membrane which has a somewhat pink hue. It is .thickest in the pyloric region and thinnest at the fundus.

DISEASES OF THE STOMACH.

The mucous membrane constitutes the glandular layer of the organ. The glands, which number about five millions, are t ubular in form and are arranged perpendicularly to the surface; at their base and around them are fibrous tissue and lymphoid cells; also a thin layer of muscles (muscularis mucosae).

Fig. 2. Fig. 3.

Fig. 2. — A Vertical Section of the Stomach, a, Mucosa; b, submucosa; c, d, muscularis;

e, serosa. X60.

Fig. 3. — A Cardiac Gland, a, Parietal cells; 6, principal cells.

The glands are composed of the following parts: (1) The mouth; (2) the neck, which is the thinnest part; (3) the body, which is much thicker, and (4) the base.

Several tubules (two to five) very frequently end in one mouth. The dots that are seen on the surface of the mucosa consist of the openings of the glands. The whole inner surface

STRUCTURE OF THE STOMACH.

of the stomach is covered by columnar epithelium, which extends for a variable distance into the mouths of the glands. The glands are divided into two kinds :

1. Cardiac or fundus glands. These fill the greater part of the stomach and are characterized by the two following features: The mouth of the gland is short as

compared with the length of the gland itself. They contain parietal or oxyntic cells, which are closely arranged in the neck of the glands. They are recognizable by being of a more or less cuboid shape and having a dark granular appearance. They are stained quite deeply with the aniline dyes.

The other cells of the glands are called the principal cells, and are somewhat smaller in shape and not so dark as the parietal cells.

2. The pyloric glands. The mouth of the gland is quite long as compared with the tube itself. The body of the gland consists almost entirely of the principal cells. Xo parietal cells are to be found here, although some cells also occur which become darkly stained with osmic acid. Nussbaum considered them similar to the parietal cells of the cardiac glands. They are usually called the Nussbaum cells.

Besides these specific glands there are a number of mucous glands in the neighborhood of the pylorus.

Heidenhain, 1 Kupffer, 2 Sachs. 3 and Stoehr 4 have greatly con-

1 Heidenhain: Archiv fur mikrosk. Anat., vol. 6, 1870.

2 Kupffer: "Epithel und Drusen des menschlichen Magens," Miinchen, 1883.

3 Sachs: Archiv f. exoerimentelle Patholog., vols. 22 and 24. * Stoehr: Archiv f. mLcrosk. Anat., vol. 20.

Fig. 4.— A Pyloric Gland, a Mouth; b, neck; c, fundus.

tributed to our knowledge of the histology of the gastric mucosa. According to these writers, the principal cells generate the pepsin and the rennet ferments, whereas the parietal or oxyntic cells are imbued with the faculty of secreting hydrochloric acid.

Blood-Vessels, Lymphatics, and Nerves of the Stomach.

The arteries of the stomach originate from the cceliac axis, the left coronary artery being a direct branch of this vessel, and the right a branch of the hepatic artery. These supply the smaller curvature and form the superior ventricular arch. The greater curvature is supplied by the right inferior coronary artery, being a branch of the hepatic artery, and by the left inferior coronary artery, which is a branch of the splenic artery; they both form the inferior ventricular arch. All these vessels reach the stomach between the folds of the peritoneum. After ramifying between the several coats and supplying them with blood (especially giving off a number of capillaries to the muscular coat), and after dividing into very small vessels in the submucous areolar tunic, their ultimate arterial branches enter the mucous membrane and ramifying freely pass between the tubuli, where they form a plexus of fine capillaries upon the walls of the tubules and also around the mouths of the glands.

The veins arise from the capillary network and pursue an almost straight course through the mucous membrane between the glands. After piercing the muscularis mucosae and forming a wide plexus in the submucous tissue, they return the residual blood into the splenic and superior mesenteric veins and also directly into the portal vein.

The lymphatics of the gastric mucosa extend, as first shown by Loven, directly to the surface of the mucosa. They form a dense network of lacunar spaces situated between and among the gland tubuli, which, as well as the blood-vessels in many parts, they enclose with sinus-like dilatations. Near the sur-

PHYSIOLOGY. 7

face of the membrane, the lymph is collected into vessels which form loops or possess dilated extremities. These vessels are less superficial than the blood capillaries, although the lacunar spaces extend as far as the basement membrane of the surface.

The nerves originate from the abdominal part of the vagus, forming the interior gastric plexus at the cardia. The vagus here extends over the whole anterior surface of the fundus. The right branch of the vagus supplies with only one-third of its fibres the stomach wall, especially the posterior wall, whereas two-thirds supply the other abdominal organs. The branches of the sympathetic nerve coming from the cceliac plexus enter into many ramifications with the vagus. These nerves, with a number of small ganglia, form a network in the submucosa.

Physiology.

The stomach forms a part of the digestive tract, and in order to understand its functions thoroughly, it will be best to give a short review of the entire process of digestion. By the term 11 digestion" are understood all processes which serve to convert the various food-stuffs into such a condition that they become fit for entrance into the circulation. These changes are effected by means of ferments, which replace the Bunsen flame of the chemist in the laboratory of the living organism. The ferments are produced by living cells, and possess certain properties in the way of effecting chemical changes when in contact with certain substances. All these changes can ultimately be explained as an hydration of anhydrides — i.e., the substances developed by their presence contain more water than the primary substances.

All ferments possess the six following qualities:

1. They are of organic nature.

2. They act only in the presence of water.

3. The total amount of the formed products contains more hydrogen and oxygen (in the relation of water) than the original substance.

4. They decompose peroxide of hydrogen.

5. They act best at temperatures varying between 30° and 60° C.

6. Each ferment possesses a specific action, and one and the same substance may develop different products when in contact with different ferments.

The ferments are divided into two classes:

1. Formed ferments; those whose active principle cannot be separated from the original cell in which they are generated and is dependent on the life of their mother substance (yeast cells).

2. Unformed ferments: those which can be separated from their original soil without losing their specific action.

Most of the ferments that exist in the living organism are unformed (ptyalin, pepsin, rennet, trypsin, etc.). Thus far all attempts to isolate ferments in a chemically pure state have been unsuccessful. We only know that they are organic bodies whose structure is similar to that of the proteids.

In the mouth the food first comes in contact with the saliva by the act of chewing. This secretion consists of the products of the salivary and mucous glands of the mouth. It is of alkaline reaction, low specific gravity (1.002-1.009), contains epithelia, mucus, ptyalin, albumin, and some salts. It also contains traces of potassium thiocyanate (CNKS). After being lubricated by the saliva, the food passes through the pharynx and oesophagus into the stomach. The ptyalin, which is characterized by converting starch into maltose or sugar, begins its action upon the food already in the mouth, but the principal work is done during the first period of digestion within the stomach.

THE GASTRIC JUICE. 9

The Gastric Juice.

Spallanzard 1 and Reaumur were the first to make experimental studies upon the gastric juice. They recognized its property of digesting meat and of exerting an antifermentative action. Prout in 1S24 discovered hydro chloric acid in the gastric juice. These experiments have been greatly furthered and advanced in this country by Beaumont, 2 who at about the same time made a series of investigations upon the well-known Canadian, St. Martin, with his gastric fistula. Many of the facts discovered by Beaumont form the basis of our knowledge of the physiology of the stomach; as, for instance, his observations on the movements of the stomach. Blondlot 3 first established a gastric fistula in animals for experimental purposes. Bidder and Schmidt 4 have conclusively shown that the acid of the gastric juice is hydrochloric acid, while Schwann in 1836 discovered the pepsin ferment. The nature of the acid of the gastric juice has been the subject of much controversy even during late years. Thus Winter and Hay em 5 disputed the formation of hydrochloric acid within the gastric glands. They assert that while the glands produce an organic acid, this is changed into an inorganic by the presence of salt (sodium chloride) within the stomach. This theory, however, is incorrect, as it is well known that the stomach will furnish a secretion containing free hydrochloric acid even when no food or other substance containing sodium chloride has been ingested.

The gastric juice is a clear, colorless fluid of an acid reaction and a specific gravity of 1.002-1.003. The quantity secreted

2 Beaumont: '"Experiments and Observations of the Gastric Juice and the Physiology of Digestion,'' Combe's edition, 1833.

3 Blondlot: "Traite analytique de la digestion," Paris, 1843.

4 Schmidt: Liebig's Annalen. xeii.. 1854.

-Winter and Hayem: "Du Chimisme Stomachale," Paris, 1891.

in twenty-four hours is not exactly known. It is estimated by some to be about three pints. The principal constituents of the gastric juice are: (1) Hydrochloric acid; (2) pepsin; (3) rennet. These two ferments Pawlow and Sawjalow 1 consider as identical. Recently a fat-splitting ferment has been discovered in the gastric juice by Volhard. 2

The degree of acidity varies from 0.1 to 0.2 per cent. Both ferments, pepsin and rennet, when first secreted are inactive bodies and called respectively pepsinogen and rennet-zymogen, but coming in contact with the acid become converted into active pepsin and rennet. Besides these three substances, the gastric juice contains water, inorganic salts, and some proteid matters.

The greatest difficulty in explaining the production of gastric juice was encountered in the circumstance that an inorganic acid should be secreted by the blood, which is a strongly alkaline solution. Maly, 3 however, gave the following explanation: Some liquids with alkaline reaction may contain acid salts; thus in the blood there exist disodic orthophosphate and monosodic orthophosphate (Na 2 HP0 4 and NaH 2 P0 4 ), together with distinctly alkaline salts. AVhen such a solution is placed into a dialyzer immersed in distilled water the acid principle passes into the latter. Thus within the dialyzer there is an alkaline and outside an acid liquid. Maly compares the stomach and the kidneys to a dialyzer, and explains in this way the secretion of acid fluids from the kidneys and from the stomach. The details of the formation of hydrochloric acid may be given as follows : If Na 2 HP0 4 is brought together with calcium chloride (CaCl 2 ), there is formed triphosphate of calcium, sodium chloride,

1 W. Sawjalow: " Zur Frage nach der Identitat von Pepsin und Chymosin." Z< itschr. f. phys. Chemie, Bd. 46, p. 307.

2 Franz Volhard: "Ueber das fettspaltende Ferment des Magens." Zeitschr. f. klin. Med., Bd. 43, Heft 5 und 6.

3 Maly: " Untersuchungen uber die Mittel zur Saurebildung im Organismus." Zeitschrift fur physiologische Chemie, i., p. 174.

GASTRIC DIGESTION. 11

and free hydrochloric acid according to the following formula: 2Na 2 HP0 4 +3Caa 2 =Ca 3 (P0 4 ) 2 H-4NaCl+2HCl.

Tins theory, although very ingenious, does not suffice to explain the entire process of gastric secretion. For there is no reason why the hydrochloric acid should not be secreted in other organs than the stomach, the blood coming into contact with many other glandular apparatuses. Besides, this theory does not explain why the secretion should not go on all the time in the stomach. Here as elsewhere we are forced to accept a specific action of the cells which cannot be explained by simply physical or chemical laws. We know that there are cells imbued with certain specific actions that are unexplainable by chemical formulae.

Gastric Digestion.

The principal part played by gastric digestion consists in the conversion of albuminates (including also connective tissue and in a considerably minor degree nuclei) into the more soluble forms of propeptones and peptones, which are the result of the combined action of hydrochloric acid and pepsin. The rennet ferment curdles milk. The gastric juice is also endowed with the property of converting cane sugar into grape sugar, and gelatin into a soluble form (a peptone) which no longer coagulates. Besides this, a small percentage of fat is split into fatty acids.

The secretion of gastric juice, according to Pawlow, 1 is under control of the nervous system, the secretory fibres being contained in the vagus. The act of eating (even when the food does not reach the stomach) produces a flow of gastric juice, provided the vagus is intact. If the latter is cut, then the mere act of eating remains without result. This proves that the sensations of taste, odor, etc., developed during eating,

1 Pawlow: "The Work of the Digestive Glands,*' translated by Thompson, reflexly stimulate the secretory fibres in the vagus nerve. This kind of secretion Pawlow designates as " psychical." Gastric secretion, being thus begun, is then supplemented by reflex stimulations arising in the stomach itself, the mucous membrane of which contains, besides sensory, also secretory nerves. Some foods (meat extracts, meat juices, soups) are particularly apt to excite secretion, while others (bread, white of egg) are ineffective. According to Pawlow the quantity and quality of the secretion vary with the character of the food.

Bayliss and Starling 1 have shown that the acid of the gastric juice, upon reaching the duodenum, produces a substance which is carried by the way of the blood stream to the pancreas, stimulating this organ to activity. This indefinite substance they have termed " secretin."

Pawlow has demonstrated the existence in the duodenum of another important substance, namely, "enterokinase," which activates the trypsinogen of the pancreatic juice into trypsin.

The work accomplished by the stomach in the act of digestion must also be ascribed to the active and passive movements that take place in this organ, in consequence of which certain physical changes are effected in the ingested food. Each particle of food is brought into more intimate contact with the stomach walls by these movements than would otherwise be possible. The food as a whole becomes more liquefied and passes, as chyme, through the pylorus into the small intestine. The pylorus is said to control the entrance of the more liquid chyme into the duodenum. It opens and closes at certain intervals. We are as yet not able to give a full explanation for this seemingly elective action of the pylorus, nor do we exactly know at what intervals the pylorus opens. It is only known that at certain times after certain meals (about two

1 Bayliss and Starling: Journal of Physiology, 1902, p. 28, 325.

GASTRIC DIGESTION. 13

hours after a small meal, six to seven hours after a large meal) the stomach is completely empty.

Recently Cannon 1 has made a study of the motions of the stomach by means of the .r-rays. He gave animals (cats) foods mixed with subnitrate of bismuth, exposed them to the Roentgen rays, and watched the action of the stomach with the fluoroscope.

Movements begin a few minutes after the entrance of food into the stomach. Contractions start in the middle of the stomach and run toward the pylorus. These waves of contraction appear at regular intervals. The pyloric portion becomes lengthened: here the peristalic waves become more pronounced with advanced digestion. These movements serve to mix the food thoroughly with the gastric juice, and to reduce it to a thin, liquid mass — chyme. At certain intervals the pyloric sphincter relaxes, and the contraction wave squeezes part of the ehynie into the duodenum with considerable force. Different foods appear to leave the stomach at various periods of time. Thus. Cannon 2 found that carbohydrate food begins to pass out from the stomach soon after ingestion, and requires only about one-half as much time as the proteids for complete gastric digestion. Fats remain long in the stomach when taken alone, and when combined with other food-stuffs markedly delay their exit through the pylorus. It is nowadays presupposed that the act of closure and relaxation of the pylorus is controlled by chemical stimuli (hydrochloric acid, etc.).

The stomach serves as a reservoir for the food until it is made fit for the passage into the small intestine, in which organ the main process of digestion takes place.

Some of the substances contained in liquefied chyme are absorbed through the stomach wall, such as sugar, salts, peptone, perhaps propeptones; the rest passes into the small in-

1 Cannon: American Journal of Physiology, 1808. p. 1. 359.

2 Cannon: American Journal of Physiology. 1904. p. 12.

testine, and is subjected to the action of several secretions that combine there in order to further change it and make it fit for absorption.

Intestinal Digestion.

Although it is not my intention to give a detailed description of the process of intestinal digestion, it might still be useful briefly to discuss the further fate of the chyme. On the entrance of the chyme into the duodenum, it is subjected to the influences of the bile and pancreatic juice, which are there poured out, and also to that of the intestinal secretion. All these secretions have a more or less alkaline reaction, and through their admixture with the chyme its acidity becomes less and less, until at length, at about the middle of the small intestine, the reaction becomes alkaline, and continues so as far as the ileo-csecal valve.

Of the bile we know that it has a strongly alkaline reaction and that it is able to emulsify fats. It also possesses antifermentative and slightly purgative properties.

The importance of the liver, however, cannot be judged from the influence which the bile exerts upon the digestive economy. "To regard the liver in this light," says L. Brunton, 1 "is just about as rational as to think that an Atlantic steamer has been built for the express purpose of throwing out from its. sides the two jets which are formed by the waste water from the engines. The condensed steam may be utilized and so may the bile, but the condensation of steam- is not the main object of an Atlantic steamer, nor is the secretion of bile a chief function of the liver."