118 



PHYSIOLOGY. 



intestine into cholin, a poisonous alkaloid; but the intestinal bac- 

 teria destroy it at once, producing methane, carbonic acid, and 

 ammonia. 



Uses of Bile. 



In fasting, not a drop of bile enters the intestine. Fat, meat 

 extractives, and the products of digestion of egg-albumin set up a 

 free' discharge of the fluid. Bile accentuates the activity of the 

 pancreatic enzymes, especially the fat-splitting ones, the action of 



Fig. 33. Curves Showing the Velocity of Secretion of Bile into the 

 Duodenum on (1) a diet of milk, uppermost curve; (2) a diet of meat, 

 middle curve; (3) a diet of bread, lowest curve. The divisions on the 

 abscissa represent intervals of thirty minutes; the figures on the ordi- 

 nates represent the volume of secretion in cubic centimeters. (HowELL, 

 after BKUNS. ) 



which is increased twofold. The pancreatic secretion, in its hourly 

 rate, corresponds closely with the entry of bile into the intestine 

 under the same conditions of diet. The similarity is most striking. 

 Bile arrests the action of pepsin, which is injurious to the ferments 

 of the pancreatic juice, and favors the ferments of the latter, espe- 

 cially the fat-splitting one. 



Bile is principally excrementitious. It partly emulsifies the fats 



