GASTRIC JUICE, AND STOMACH DIGESTION. 135 



tary glands of the small intestine. These follicles, which are not very 

 numerous, are seated in the lower part of the mucous membrane, 

 and enveloped by the caecal extremities of the tubules. (Fig. 27, a.) 



In the cardiac portion of the stomach, the tubules are very wide 

 in the superficial part of the mucous membrane, and lined with 

 large, distinctly marked cylinder epithelium cells. (Fig. 29.) In the 

 deeper parts of the membrane they become branched and conside- 

 rably reduced in size. From the point where the branching takes 

 place to their termination below, they are lined with small glandular 

 epithelium cells, and closely bound together by intervening areolar 

 tissue, so as to present somewhat the appearance of compound 

 glandules. 



The bloodvessels which come up from the submucous layer of 

 areolar tissue form a close plexus around all these glandules, and 

 provide the mucous membrane with an abundant supply of blood, 

 for the purposes both of secretion and absorption. 



That part of digestion which takes place in the stomach has 

 always been regarded as nearly, if not quite, the most important 

 part of the whole process. The first observers who made any 

 approximation to a correct idea of gastric digestion were Keaumur 

 and Spallanzani, who showed by various methods that the reduction 

 and liquefaction of the food in the stomach could riot be owing to 

 mere contact with the gastric mucous membrane, or to compression 

 by the muscular walls of the organ ; but that it must be attributed 

 to a digestive fluid secreted by the mucous membrane, which pene- 

 trates the food and reduces it to a fluid form. They regarded this 

 process as a simple chemical solution, and considered the gastric 

 juice as a universal solvent for all alimentary substances. They 

 succeeded even in obtaining some of this gastric juice, mingled 

 probably with many impurities, by causing the animals upon which 

 they experimented to swallow sponges attached to the ends of 

 cords, by which they were afterward withdrawn, the fluids which 

 they had absorbed being then expressed and examined. 



The first decisive experiments on this point, however, were those 

 performed by Dr. Beaumont, of the U. S. Army, on the person of 

 Alexis St. Martin, a Canadian boatman, who had a permanent gas- 

 tric fistula, the result of an accidental gunshot wound. The musket, 

 which was loaded with buckshot at the time of the accident, was 

 discharged, at the distance of a few feet* from St. Martin's body, in 

 such a manner as to tear away the integument at the lower part of 

 the left chest, open the pleural cavity, and penetrate, through the 



