1 20 Life and Health 



The inner surface of the small intestine also secretes a 

 liquid called intestinal juice, the precise functions of which 

 are not known. The chyme, thus acted upon by the dif- 

 ferent digestive fluids, resembles a thick cream and is now 

 called chyle. The chyle is thrust along the small intestine 

 by th.e contractions of its muscular walls. 

 -V 181. Digestion in the Large Intestines. Digestion does 

 not occur to any great extent in the large intestines. The 

 food enters this portion of the digestive canal through 

 the ileo-caecal valve and travels through it slowly. The 

 remains of the food now become less and less fluid, and 

 consist of undigested matter which has escaped the action 

 of the several digestive juices, or which has withstood their 

 influence. Driven onward by the contractions of the mus- 

 cular walls, the waste material at last reaches the rectum, 

 from which it is voluntarily expelled from the body. 



ABSORPTION 



182, Absorption. While food remains within the alimen- 

 tary canal it is outside of the body, so far as nutrition is 

 concerned. To be of any service the food must be absorbed 

 by the blood. 



The efficient agents in absorption are the blood vessels 

 and the lymphatics. The process by which the nutritious 

 material enters the blood is called absorption. It is a 

 process not confined, as we shall see, simply to the 

 alimentary canal, but one that is going on in every tissue. 

 The vessels by which the process of absorption is carried 

 on are called absorbents, or lymphatics, 

 y. 183. Absorption by the Mouth and Stomach. The lining 

 of the mouth and oesophagus is not well adapted for 

 absorption. That this does occasionally occur, however, 



