186 ELEMENTS OF AGRICULTURE 



CHAPTEE XXXIV.— Food, Work, and Growth 

 of Animals 



177. Animals and Plants are Alike in Composition. — 



In the last chapter we learned that in composition 

 animal bodies closely resemble plants. This is not sur- 

 prising when we consider the fact that the food of 

 animals consists principally of plants. It is true that 

 some animals are carnivorous, that is, they live on the 

 flesh of other animals, but the animals so used for food 

 derive their food from plants. 



178. Plants Manufacture Food for Animals. — While 

 plants and animals are much alike in composition they 

 differ very much in their manner of taking in food and 

 growing. Plants as a rule take up the necessary raw 

 materials from the earth and air, and change them 

 into the compounds which make up their supply of 

 protein, carbohydrates, fats, etc. Animals as a rule 

 have not this power of taking the raw materials into 

 their bodies and changing them into other compounds. 

 A horse or cow will starve on the food that supplies 

 plants* even though this food contains all the elements 

 found in the animal's body. The raw materials of the 

 earth and air must first be made into plants before they 

 are fit food for animals. Plants are the makers of 

 animal food. 



179. All Living Animals are Constantly Growing. — 

 The growth of young animals is generally rapid; they 

 increase in size till they reach the point where they 



