THE GASES OF THE STOMACH. 



301 



That the stomach is also capable of digesting parts of a living body is shown 

 by the fact that the thigh of a living frog or the ear of a rabbit, introduced into a 

 gastric fistula in a dog, will be partly digested. The edges of gastric ulcers and 

 fistulas in human beings are also eroded by the digestive activity of the gastric 

 juice. The question was early asked, Why does the stomach-wall not digest 

 itself? As, after death, the mucous membrane is, in fact, often rapidly softened 

 by autodigestion (gastric softening), the opinion is justified that, so long as the 

 circulation is maintained, the tissues are constantly protected against the action 

 of the acid by the alkalinity of the blood. If the reaction of the gastric juice be 

 alkaline, digestion cannot be inaugurated. Ligation of the blood-vessels of the 

 stomach resulted, according to Pavy's investigations, in digestive softening of the 

 gastric mucous membrane. In human beings morbid occlusion of the vessels 

 causes, in an analogous manner, the development of gastric ulcers. Also the thick, 

 firmly adherent layer of mucus may help to protect the uppermost layer of the 

 mucous membrane against autodigestion. In general, however, the conditions, 

 with respect to all peptonizing ferments, are such that fully living protoplasm, 

 therefore also that of the epithelial cells of the stomach, possesses the property 

 of being able to resist the action of enzymes, as it is capable of decomposing all, 

 even the most complicated, molecules of inanimate substances. Amcebae, bacteria, 

 worms, larvae and embryonal vegetable cells are not affected by artificial digestive 

 juices, not even by trypsin. 



After extirpation of the stomach, digestion is continued by the pancreas, the 

 liver and the intestines. The stomach is a protective apparatus with respect to 

 the intestine, as it removes various injurious influences, particularly of bacterial 

 origin. 



THE GASES OF THE STOMACH. 



The stomach always contains gases, derived in part from air directly 

 swallowed, as, for example, with the saliva, and in part from gases that 

 pass backward from the duodenum. 



If the larynx and the hyoid bone are suddenly drawn forcibly forward (as in 

 vomiting), a considerable amount of air enters the space behind the larynx and 

 when the latter returns to its position of rest, is carried down by the peristalsis of 

 the esophagus. One can feel distinctly the downward passage of such a quantity 

 of air. At times, even without any movement of deglutition, a number of small 

 air-bubbles enter the stomach. 



These masses of air constantly undergo change, owing to the absorp- 

 tion of oxygen into, and the elimination of carbon dioxid from, the 

 blood. The rather abundant production of carbon dioxid in the 

 stomach depends, however, on chemical processes resulting from the 

 admixture of the pyloric secretion, containing sodium carbonate, with 

 the secretion of the fundus, containing acid. According to Planer, the 

 amount of oxygen is extremely small, while that of carbon dioxid is 

 considerable. 



A portion of the carbon dioxid in the saliva is set free by the acid of 

 the gastric juice. The quantity of nitrogen is indifferent. 



GASES OF THE STOMACH. VOLUMES IN PER CENT. 



(According to Planer.) 



