52 THE VITAL FUNCTIONS. 



together a certain number of elements derived from 

 the mineral kingdom, in order to subject them to 

 the operations of vital chemistry, a power too subtle 

 for human science to detect, or for human art to 

 imitate ; and by wliich these materials are com- 

 bined into a variety of nutritive substances. Of 

 these substances, so prepared, one portion is con- 

 sumed by the plants themselves in maintaining 

 their own structures, and in developing the em- 

 bryos of those which are to replace them ; another 

 portion serves directly as food to various races of 

 animals ; and the remainder is either employed in 

 fertilizing the soil, and preparing it for subsequent 

 and more extended vegetation, or else, buried in 

 the bosom of the earth, it forms part of that vast 

 magazine of combustible matter, destined to benefit 

 future communities of mankind, when the arts of 

 civilization shall have developed the mighty ener- 

 gies of human power. 



Chapter III. 



ANIMAL NUTRITION IN GENERAL. 



§ I . Food of Animals, 



Nutrition constitutes no less important a part of 

 the animal, than of the vegetable economy. En- 

 dowed with more energetic powers, and enjoying 

 a wider range of action, animals, compared with 

 plants, require a considerably larger supply of nu- 



