HOW FOOD IS DIGESTED 2J 



both nutriment and the waste or broken-down mat- 

 ter of the body. The part of the absorbed food 

 that enters into the lymphatic system is carried to 

 the thoracic duct, which extends along the spinal 

 column, and enters one of the main blood vessels. 

 The lymph is blood without the red blood corpuscles. 

 It wanders to all parts of the body, surrounds all 

 the cells in all the tissues and carries to the cells the 

 very kind of food they most need. 



Once the food gets into the circulatory system it 

 takes the regular course of the blood. In impure 

 blood it goes to the right auricle of the heart, 

 then to the right ventricle. This in turn contracts 

 and forces the blood into the lungs, where oxygen 

 is taken on and carbonic acid gas and other impu- 

 rities are given off. From the lungs the blood, now 

 red and pure, passes into the left auricle, and thence 

 into the left ventricle, from which it is forced into 

 the aorta, to be distributed to all parts of the body. 



Villi Cells. The digested food in the intestines is 

 gathered in by the villi cells. The mucous mem- 

 brane lining the small intestines possesses highly 

 differentiated structures that appear as minute 

 fingers. These tiny, hair-like projectiles reach into 

 the intestinal mass for sugar, peptones and fatty 

 acids, which they transfer, through the cells, into 

 the absorbent vessels or lymphs that in turn empty 

 the assimilated stores of food into larger and still 

 larger vessels. This process continues until the 

 whole of the nutritive fluid is collected in the cir- 

 culatory system to become the very basis of the 

 blood. 



