Mastication, Digestion and AssimAlaiion. 25 



gro^vth, or, if no growth occurs, the serum albumen repairs the 

 waste of body tissue incident to life and action. 



44. Fat nutrition. — The fats contained in the food are largely 

 absorbed unchanged in the form of an emulsion. A small per- 

 centage of fat enters the blood through the blood vessels lining the 

 intestines, but the larger portion through the lymphatics. Though 

 fats enter the circulation unchanged, they are generally in some 

 manner modified by the animal consuming them, so that when 

 built into fatty tissue that of each species has its own character- 

 istics. 



45. Carbohydrate nutrition. — The carbohydrates are converted 

 into some form of sugar, which enters the blood by absorption 

 from the intestinal canal. In the liver, sugar is converted into 

 glycogen and held as reserve, or it is rapidly oxidized into car- 

 bonic acid and water, the intermediate products being unknown. 

 Carbohydrates in excess of immediate requirement may be con- 

 verted into fat and stored in the body. There is no starch in the 

 body of animals. 



