NUTRITION PROPER. 



289 



animals and plants. Examples of the second are the 

 sugars and starches, and of the third all the animal and 

 vegetable fats and oils. The following schedule ex- 

 presses most of these facts : 



Name. 



Food 



Albuminoids 

 Amyloids. . . . 

 Fats 



Composition. 



j C, H, O, N, etc., Quater- 

 ( nary 



C, H, O, Ternary 



+ - 



C, H, O, Ternary 



Examples. 



/ Fibrin, albumen, 

 •j protein, gluten, 

 ( protoplasm. 

 Starches and sugars 



Fats and oils. 



Milk. — The material prepared by Nature as the food 

 of the young of mammals must contain all these. Albu- 

 minoids are represented by the casein, or curd ; amyloids, 

 by the milk-sugar; and fats by the butter. 



Uses of Food. — The uses of food are twofold, viz., 

 (1) for tissue-building — i.e., repair of waste in the adult 

 and repair and growth in the young; (2) iox force and 

 heat making by combustion, or, we may say briefly, tissue 

 food and fuel food. This is expressed by schedule: 



l Repair. 

 ' ' ' j Growth. 

 ( Force. 

 ' ' I Heat. 



We say fuel for force and neat, but the real ob- 

 ject in the animal body, as in the steam engine, is 

 force, although, in both, heat is a necessary concomi- 

 tant. In the case of the body it is sometimes an in- 

 different concomitant, as in a moderate temperature ; 

 sometimes a very comfortable concomitant, as in cold 

 weather; and sometimes a distressing concomitant, as 

 in very hot weather. We will explain this more fully 

 hereafter. 



Food. 



Tissue . 

 Fuel. . . 



