DIGESTION. 207 



eliminated from the body .^ The bile is thus a compound of both 

 secretory and excretory principles^ 



The flow of bile from the liver is continuous but subject to con- 

 siderable variation during the twenty-four hours. The introduction 

 of food into the stomach at once causes a slight increase in the flow, 

 but it is not until about two hours later that the amount secreted 

 reaches its maximum; after this period it gradually decreases up to 

 the eighth hour, but never entirely ceases. During the intervals of 

 digestion though a small quantity passes into the intestine, the main 

 portion is diverted into the gall-bladder, where it is retained until 

 required for digestive purposes. When acidulated food passes over 

 the surface of the duodenum there is excited, through reflex action, 

 a contraction of the muscular walls of the gall-bladder and ducts and 

 a gush of bile into the intestine, the discharge continuing intermit- 

 tently until digestion ceases and the intestine is emptied of its con- 

 tents. 



<^The total quantity of bile secreted daily has been estimated to be A, / 

 from 500 to 800 grams^^" 



Physiologic Action of Bile. Notwithstanding our knowledge &M 

 of the complex composition of bile, the quantity discharged daily, and / 

 the time and place of its discharge, its exact relation to the digestive 

 process has not been fully determined. &zNo specific action can be 

 attributed to it... It has but a slight, if any, diastaticltction on starch. 

 It is without influence on proteids. By virtue of the bile salts it con- 

 tains, it hastens the action of pancreatic juice in splitting neutral oils 

 into fatty acids and glycerin, and in this way aids in their digestion. 

 The bile salts also dissolve insoluble soaps, which may be formed 

 during digestion. 



Bile : favorsdiedigestion^lial. If it be excluded from the intes- 

 tine tr^re^7mm^m^e^6cesTrom 22 to 58 per cent, of the ingested 

 fats. At the same time the chyle, instead of presenting the usual 

 white creamy appearance, is thin and slightly yellow. The manner 

 in which the bile promotes fat digestion is yet a subject of investiga- 

 tion. If all the fat is converted into fatty acid and glycerin, with the 

 formation of soaps, as seems probable, the action of the bile becomes 

 more apparent from the fact, already stated, that it dissolves and 

 holds in solution the soaps so formed which would be necessary to 

 their absorption by the epithelial cells. As an aid tojiigestion the 

 bile has been regarded as important, for the reason mat its entrance 

 into the intestine is attended by a neutralization and precipitation of 

 the proteids which have not been fully digested and are yet in the 

 stage of acid-albumin. In this way gastric digestion is arrested and 

 the foods are prepared for intestinal digestion. 



Though bile possesses no antiseptic properties outside the body, 

 itself undergoing putrefactive changes very rapidly, it has been 



