512 DIGESTION. 



because it retards the swelling up of the proteins. The passage of bile 

 into the stomach during digestion on the contrary, seems, according, 

 to several investigators, especially ODDI and DASTRE/ to have no dis- 

 turbing action on gastric digestion. According to BoLDYREFF, 2 after 

 continuous starvation, on feeding fat and food rich in fat, as well as after 

 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 digestion 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. 

 According to BAUMSTARK and COHNHEIM 3 connective tissue is digested 

 on the other side of the pylorus in the intestine by the pepsin-hydrochloric 

 acid. On the contrary, the bile does not disturb the digestion of pro- 

 teins by the pancreatic juice in the intestine. The action of these diges- 

 tive 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 trypsin is accelerated by the bile. In a dog killed while 

 digestion is going on, the faintly acid, bile-containing material of the 

 intestine shows regularly a strong digestive action on proteins. 



The precipitate of protein and bile-salts 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 hydro- 

 chloric 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 pre- 

 cipitation 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-organ- 

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



1 Oddi, in Centralbl. f. Physiol., 1, 312; Dastre, Arch, de Physiol. (5), 2, 316. 

 8 Centralbl. f. Physiol., 18, 457, and Pfluger's Arch., 121. 

 3 Zeitschr. f. physiol. Chem., 65, 477 (1910). 



