162 THE HUMAN BODY. 



arj canal to be got rid of. But there are many reasons 

 against such a view. In the first place, the entry of the 

 bile into the upper end of the small intestine, where it 

 has to traverse a course of more than twenty feet before 

 getting out of the body, makes it probable that bile has 

 some function to fulfill in the intestine. One use is 

 no doubt to assist by its alkalinity in overcoming the 

 acidity of the chyme, and so to allow the pancreatic secre- 

 tion to act upon proteids. Constipation is also apt to 

 occur in cases where the bile-duct is temporarily stopped, 

 so that the bile probably helps to excite the contrac- 

 tions of the muscular coats of the intestines; and it is 

 said that when the bile secretion is deficient putrefactive 

 changes are extremely apt to occur in the intestinal con- 

 tents. Apart from such secondary actions, however, the 

 bile probably has some influence in promoting the absorption 

 of fats. If one end of a very narrow glass tube moistened 

 with water be dipped in oil the latter will not rise in it, or 

 but a short way; but if the tube be moistened with bile 

 instead of water the oil will ascend higher. Again, oil 

 passes through a plug of porous clay kept moist with bile, 

 under a much lower pressure than through one wet with 

 water. Hence bile by moistening the cells lining the intes- 

 tine may facilitate the passage into the villi of oily sub- 

 stances. At any rate, experiment shows that if the bile be 

 prevented from entering the intestine of a dog the animal 

 eats an enormous amount of food compared with that 

 amount which it needed previously; and that of this food 



Give reasons for believing that bile is not a mere excretion. How 

 does bile aid the digestive power of the pancreas? Point out other 

 uses of bile. Describe experiments which iind to prove that bile 

 helps in promoting the absorption of fatty matters from the intes- 

 tine. 



