REQUIRED BY THE HERBIVORA. 165 



tainly to be served by the bile (the most highly car- 

 bonized product of the transformation of their tissues) 

 in the bodies of the carnivora. These substances 

 are employed to support certain vital actions, and 

 are finally consumed in the generation of animal 

 heat, and in furnishing means of resistance to the 

 action of the atmosphere. In the carnivora, the 

 rapid transformation of their tissues is a condition of 

 their existence, because it is only as the result of 

 the change of matter in the body that those sub- 

 stances can be formed, which are destined to enter 

 into combination with the oxygen of the air ; and 

 in this sense we may say that the non-azotised con- 

 stituents of the food of the herbivora impede the 

 change of matter, or retard it, and render unneces- 

 sary, at all events, so rapid a process as occurs in 

 the carnivora. 



68. The quantity of azotised matter, proportion- 

 ally so small, which the herbivora require to sup- 

 port their vital functions, is closely connected with 

 the power possessed by the non-azotised parts of 

 their food to act as means of supporting the respi- 

 ratory process ; and this consideration seems to 

 render it not improbable, that the necessity for 

 more complex organs of digestion in the herbivora 

 is rather owing to the difficulty of rendering soluble 

 and available for the vital processes certain non- 

 azotised compounds (gum ? amylaceous fibre ?) than 

 to any thing in the change or transformation of 

 vegetable fibrine, albumen, and caseine into blood; 



