CHAPTER XVII. 

 DIGESTION IN THE INTESTINE. 



The Parts of the Intestine. The intestine consists of two 

 parts : first, the long and narrow small intestine ; second, 

 the short and wide large intestine. (See Fig. 76.) 



The Small Intestine. The small intestine has essentially 

 the same structure as the parts of the digestive tube already 

 studied; namely, a muscular coat and a mucous lining. The 

 muscular coat has two layers, one of circular and the other 1 

 of longitudinal fibers. The muscular coat mixes the juices 

 with the food and moves it along. The muscular action 

 of the intestines is a slow writhing motion, called peristaltic 

 action. The mucous coat supplies mucus, which keeps 

 the surface soft and smooth. 



The Liver. The liver is just under the diaphragm. It 

 is convex above, where it fits the hollow under surface of 

 the diaphragm, and hollow below, where it fits over the 

 upper surface of the stomach. The greater part of it is 

 on the right, as the greater part of the stomach is on the 

 left, side of the body. The liver is dark colored and of 

 very delicate structure, chiefly because it has very little 

 connective tissue. It is the largest gland in the body, 

 weighing nearly four pounds. 



Bile. Bile is a bitter, golden red, or sometimes greenish 

 yellow, liquid made by the liver from the blood. About 

 two and a half pints of bile are made daily. 



