DIGESTION. 



167 



the walls of the stomach and abdomen, the result either of accident or of 

 necessary surgical or experimental procedures. 



The earliest observations on gastric digestion were made by Dr. Beau- 

 mont on Alexis St. Martin, who, as the result of a gunshot wound, was left 

 with a permanent fistulous opening into the fundus of the stomach. This 

 opening two years after the accident was about two and a half inches in 

 circumference and usually closed from within by a fold of mucous mem- 

 brane which prevented the escape of the food. This valve could be readily 

 displaced by the finger and the interior of the stomach exposed to view. 

 After the complete recovery of St. Martin, Dr. Beaumont during the years 

 between 1825 and 1831 at intervals made numerous experiments on the 

 nature of gastric digestion. As the result of an admirable series of investi- 

 gations it was established that the digestion of the food is largely a chemic 

 act, due to the presence of an acid fluid secreted by the mucous membrane; 

 that this fluid is secreted most abundantly after the introduction of food into 

 the stomach; that different articles of food 

 possess varying degrees of digestibility; that 

 the duration of digestion varies according to 

 the nature of the food, exercise, mental states, 

 etc., and that the process is aided by contin- 

 uous movements of the muscle walls. 



Since Dr. Beaumont's time the establishing 

 of a gastric fistula in human beings has been 

 necessitated by pathologic conditions of the 

 esophagus. After recovery these cases offered 

 fair facilities for the study of the process when 

 the food was introduced through the opening. 

 Similar fistulae have been established in both 

 carnivorous and herbivorous animals with a 

 view of studying the process as it takes place 



them. The results obtained in these in- 



m 



FIG. 75. DIAGRAM SHOWING 

 THE RELATION OF THE NATURAL 

 STOMACH TO THE MINIATURE 

 STOMACH OR POUCH MADE AC- 

 CORDING TO THE PROCEDURE DE- 

 VISED BY PAWLOW. V. The nat- 

 ural stomach. 5. The miniature 

 stomach, e, e. The septum formed 

 by the mucous membrane. A, A. 

 The abdominal walls. 



stances in many respects corroborate those 

 obtained by Dr. Beaumont, though many new 

 facts, unobserved by him, have been brought 

 to light. 



Much additional information as to the mode of secretion and the char- 

 acteristics of the gastric juice has been obtained, since the introduction of two 

 new procedures by Pawlow. The first consists in establishing a gastric 

 fistula and subsequently dividing the esophagus in the neck, and then so 

 adjusting the divided ends that they heal separately into an angle of the skin 

 incision. The second procedure consists in forming a diverticulum or pouch 

 out of the cardiac end of the stomach which opens on the surface of the ab- 

 domen but is separated from the rest of the stomach by a thin septum formed 

 oftwo layers of mucous membrane. (Fig. 75.) The serous and muscle-coats 

 of this pouch are in direct continuity with the large stomach and all possess 

 the same vascular and nerve connections. Because of this fact this miniature 

 stomach, about one- tenth the size of the natural stomach, exhibits the same 

 phenomena, so far as the secretion of the gastric juice is concerned, as the 

 large stomach does. The phenomena which are observed in it may be taken 



