NUTRITION OF CARNIVOROUS ANIMALS. 155 



tion sufficient for the metamorphosis of an adequate amount 

 of tissue, that enough carbon and hydrogen may be set free 

 for the support of the respiratory process. And we see a cor- 

 responding activity in the Human hunters of the swift-footed 

 antelope and agile deer, which answers a similar purpose ; and 

 which is remarkably contrasted with the stupid inertness of 

 the inhabitants of the frigid zone, that is only occasionally 

 interrupted by the necessity of securing the supplies of food 

 afforded by the massive tenants of their seas. 



161. The nutrition of the Carnivorous races may, then, be 

 thus described. The bodies of the animals upon which they 

 feed, contain flesh, fat, &c., in nearly the same proportion as 

 their own ; and all, or nearly all, the aliment they consume, 

 goes to supply the waste in the fabric of their own bodies, 

 being converted into its various forms of tissue. After having 

 remained in this condition for a certain time, varying ac- 

 cording to the use that is made of them, these tissues un- 

 dergo another metamorphosis, which ends in restoring them 

 to the condition of inorganic matter ; and thus give back to 

 the mineral world the materials which were drawn from it by 

 plants. Of these materials, part are burned off, as it were, 

 within the body, by union with the oxygen of the air taken 

 in through the lungs, from which organs they are discharged 

 in the form of carbonic acid and water : the remainder are 

 carried off in the liquid form by other channels. Hence 

 we may briefly express the destination of their food in the 

 following manner : 



( Carbonic acid and 



\ water thrown Off 







other excretions. 



162. But in regard to the Herbivorous animals, the case 

 is different. They perspire much more abundantly, and their 

 temperature is thus continually kept down ( 372). They 

 consequently require a more active combustion, to de- 

 velop sufficient bodily heat ; and the materials for this are 

 supplied, as we have seen, by the non-azotized constituents of 

 their food, rather than by the metamorphosis of their own 

 tissues, which takes place with much less rapidity than in 

 the carnivorous tribes. Hence we may thus express the 



