DIGESTION 



137 



open the terminations of the ducts of the liver and pancreas, organs which 

 secrete the bile and pancreatic juice respectively. The large intestine is 

 from one and three quarters to two meters in length and extends from the 

 end of the small intestine to the anus. Its walls contain a large number of 

 glands. 



The general process of digestion is largely accomplished by the chemic 

 action of the digestive fluids secreted by glands, some of which are imbedded 



FIG. 59. DIAGRAM OF THE ALIMENTARY CANAL. (Modified from Landois.} 



in the walls of the canal while others are situated outside of it and com- 

 municate with it only by means of ducts. These fluids are the saliva, the 

 gastric, intestinal, and pancreatic juices, and the bile. Though taking 

 place throughout a large portion of the food canal, the process may be sub- 

 divided into several stages: viz., prehension, mouth digestion, deglutition, 

 gastric digestion, and intestinal digestion. 



As a result of the action of these fluids the nutritive principles are pre- 

 pared for absorption into the blood; the non-nutritive principles, along 



