96 NUTRITIONAL PHYSIOLOGY 



insoluble and are not always successfully carried to the 

 intestine by the bile. When they deposit in solid form in 

 the gall-bladder they contribute to the formation of "gall- 

 stones," aggregations in which another waste-product, 

 the waxy cholesterin, may be included. The pigments are 

 usually more or less altered by bacterial action in the 

 course of their journey through the canal, and eventually 

 become the chief coloring-matter of the feces. 



The bitter taste of bile is due to. two organic salts of 

 high molecular weight. These seem to have a totally dif- 

 ferent significance from that of the pigments and choles- 

 terin. They are not lost to the body, but are absorbed 

 from the lower part of the small intestine and are presum- 

 ably secreted again and again. This phenomenon has 

 been spoken of as the "circulation of the bile-salts." The 

 withholding of these bodies from the alimentary tract tends 

 to derange digestion and, in particular, to diminish the 

 absorption of fats. When bile is tested by itself it shows 

 only the feeblest digestive powers, yet pancreatic digestion 

 is greatly promoted by its presence, and it may be likewise 

 an ally of the intestinal juice. 



Light is thrown on the properties of the bile by observing 

 the condition of jaundice. This disorder is commonly 

 caused by the more or less general plugging of the bile- 

 ducts with mucus. The secretion cannot make its escape 

 from the liver in the normal way and some of it enters the 

 circulation. Bile-pigments make their appearance in the 

 white of the eye and in the skin. The urinary pigment, 

 which is always closely related to the pigments of the bile, 

 is much increased. The ill feeling which usually attends 

 the condition may be due in part to the mildly poisonous 

 effect of the abnormally retained bile constituents. It is 

 likely to be aggravated by indigestion. The bile-salts are 

 lacking and the capacity to digest the food and promptly 

 absorb the end-products is greatly reduced. Bacterial 

 action in the intestine may become pronounced. This 

 last fact has suggested that the bile may be an antiseptic. 

 It cannot be shown to have anything like a universal action 

 of this kind, but it is very probable that it has a selective 



