DIGESTION 



liquid peptone. It changes starch to sugar, but far more 

 powerfully than the saliva. It causes fat to become broken 

 into fine particles, which will mix with water. It also 

 changes some fat to soap. 



Third. Above the stomach there is a large red gland 

 ^called the liver. Each day it pours into the intestine 

 about a quart of a yellow and 

 bitter liquid called bile. Bile 

 itself does but" little of the 

 work of digestion, but its pres- 

 ence doubles the power of the 

 pancreatic juice. Bile is a 

 waste substance, but on its 

 way out of the body it helps 

 in the work of building up the 

 body. 



33. Movements of the intes- 

 tine. Like the mouth and 

 stomach, the intestine mixes 

 the food with the juices, and 



forces it alone: its tube. As a e P itheli um <> f the surface of the 



stomach, 



food goes farther and farther b epithelium lining the tubes of the 



down, it becomes more and glands. 



c connective tissue between the tubes. 



more liquid, until at the end 



only such things as very large lumps of food, or husks and 

 peelings, remain solid. The food now looks like milk, 

 with undigested particles floating in it. It is still as much 

 outside the body as though it were held in the closed 

 mouth. It must pass through the wall of the intestine 

 and enter the blood stream before it can feed the cells. 



34. How food gets into the blood. Many blood tubes 

 lie almost upon the surface of the intestine, while many 

 more lie upon tiny fingers called villi, which reach from 



Gastric glands in the stomach 



(X200). 



