104 THE BIOLOGY OF AN ANIMAL. 



general effect of the metabolism of the animal is the destruction 

 by oxidation of organic matter ; that is, matter originally taken 

 from the environment in the form of complex proteids, fats, and 

 carbohydrates is returned to it in the form of sunpler and more 

 highly oxidized substances, of which the most important are car- 

 bon dioxide and water (both inorganic substances). This action 

 furthermore is accompanied by a dissipation of energy — that is, 

 a conversion of potential into kinetic energy. 



On the whole, therefore, the action of the animal upon the 

 environment is that of an oxidizing agent, a reducer of comj^lex 

 compounds to simpler ones, and a dissipator of energy. And 

 herein it is typical of animals in general. 



