142 THE DIGESTIVE FLUIDS. 



controlling the intensity of the putrefactive and fermentative proc- 

 esses which even normally take place in the lower intestinal tract. 

 It has now been definitely established, however, that, aside from its 

 emulsifying action upon fats, the secretion possesses no digestive 

 properties whatever, and is likewise without effect upon the bacteria 

 which are normally found in the intestinal canal. \Ye accordingly 

 find that in animals and in man the processes of nutrition are in no 

 way interfered with if the bile is prevented from entering the 

 digestive tube, but is carried to the outside through the establish- 

 ment of a fistulous opening in the common duct, provided that food 

 is administered which contains but little fat. With a diet consist- 

 ing of albumins and carbohydrates digestion thus continues unim- 

 paired, and the animal is capable of maintaining its nitrogenous 

 equilibrium practically as before. If fats, however, are given at the 

 same time in large amounts, more or less serious digestive disturb- 

 ances soon develop, and the animal loses weight. In such cases it 

 has been ascertained that whereas normally from 2 to 10 per cent, 

 of the ingested fat is eliminated in the feces, from 31 to 47 per cent, 

 now escapes resorption. The offensive gases which are then passed 

 by the animal are referable to an increase of the putrefactive proc- 

 esses in the intestines, it is true. This is, however, not owing to 

 the absence of bile per se, but to the fact that the unabsorbed fats 

 envelop the albuminous material, and thus prevent its further diges- 

 tion, so that in the lower portion of the digestive canal, where the 

 putrefactive processes are most intense, the bacteria find an increased 

 amount of pabulum at their disposal, and an increase of the putre- 

 factive products accordingly results. In the presence of bile, on the 

 other hand, this does not occur, as its emulsifying effect upon the 

 fats soon leads to their absorption, and thus leaves the albumins 

 exposed to the action of the digestive juices, and to their resorption 

 in turn. Indirectly, it can thus control the process of putrefaction, 

 but such action is not due to any germicidal or antiseptic properties 

 of its own. On withdrawing fats from the food and giving an ade- 

 quate supply of carbohydrates, normal relations are soon re-estab- 

 lished, though the bile is absent as before. 



The bile in reality represents a most important excretory product 

 of the animal body, and may in this sense be compared to the 

 urine. It appears, moreover, that those waste-products which are 

 markedly toxic in action, and could not be carried to the kidneys 

 through the blood-current without seriously disturbing the general 

 health, are formed in the liver directly, and are hence removed 

 through separate channels in the bile. 



Substances are further eliminated in this manner which, like 

 cholesterin, are insoluble in water, and could hence not be excreted 

 by the kidneys. 



For convenience' sake, however, the bile is described at this place. 



Secretion. As found in the gall-bladder, the bile represents the 

 secretory product of the liver-cells which is eliminated into the 



