490 DIGESTION. 



large amounts of acid, a mixture of bile, pancreatic juice, and intestinal 

 juice pass readily into the stomach. After food rich in fat, which retards 

 the secretion of gastric juice and the motility of the stomach, a diges- 

 tion due to this alkaline mixture may take place in the stomach. 



Bile itself has no solvent action on proteins in neutral or alkaline 

 reaction, but still it may exert an influence on protein digestion in the 

 intestine. The acid contents of the stomach, containing an abundance 

 of proteins, give with the bile a precipitate of proteins and bile-acids. 

 This precipitate carries a part of the pepsin with it, and for this reason, 

 and also on account of the partial or complete neutralization of the acid 

 of the gastric juice by the alkali of the bile and the pancreatic juice, 

 the pepsin digestion cannot proceed further in the intestine. On the 

 contrary, the bile does not disturb the digestion of proteins by the pan- 

 creatic juice in the intestine. The action of these digestive secretions, 

 as above stated, is not disturbed by the bile, not even by the faintly acid 

 reaction due to organic acids; but, on the contrary, the action of tryp- 

 sin is accelerated by the bile. In a dog killed while digestion is going 

 on, the faintly acid, bile-containing material of the intestine shows regu- 

 larly a strong digestive action on proteins. 



The precipitate formed on the meeting of the acid contents of the 

 stomach with the bile easily redissolves in an excess of bile and also in the 

 NaCl formed in the neutralization of the hydrochloric acid of the gastric 

 juice. This may take place even in faintly acid reaction. Since 

 in man the excretory ducts of the bile and the pancreatic juice open near 

 one another, in consequence of which the acid contents of the stomach 

 are probably immediately in great part neutralized by the bile as soon 

 as it enters, it is doubtful whether a precipitation of proteins by the bile 

 occurs in the intestine. 



Besides the previously mentioned processes caused by enzymes, 

 there are others of a different nature going on in the intestine, 

 namely, the fermentation and putrefaction processes caused by micro- 

 organisms. These are less intense in the upper parts of the intestine, 

 but increase in intensity toward the lower part, and decrease in the 

 large intestine because of the consumption of fermentable material and 

 by the removal of water by absorption. Fermentation processes, but 

 only very slight putrefaction, occur in the small intestine of man. 

 MACFADYEN, M. NENCKI, and N. SEEBER l have investigated a case 

 of human anus praBternaturlis, in which the fistula occurred at the 

 lower end of the ileum, and they were able to investigate the con- 

 tents of the intestine after it had been exposed to the action of the mucous 

 membrane of the entire small intestine. The mass was yellow or yellowish 



1 Arch. f. exp. Path. u. Pharm., 28. 



