SOUECES OF NUTfilBNTS 



57 



Chart I. 



origin, but if we consider for a moment the Icinds of ani- 

 mals upon which we depend for food it is noteworthy that 

 these animals themselves feed exclusively upon vegetable 

 and mineral matter. We may say, then, that with the 

 exception of some mineral salts and water, the animal 

 world in general ultimately derives all its supply of nutri- 

 ents from the vegetable world. When we eat flesh we are 

 simply using the proteid, carbohydrate, and fat that these 

 animals have themselves obtained from vegetable matter. 

 It is in the plant, then, that the chemical compounds 



