74 GRAMINIVORA REQUIRE 



XIV. In these different substances, some one of 

 which is never wanting in the food of the gramni- 

 vora, there is added to the nitrogenised constituents 

 of this food, to the vegetable albumen, fibrine, and 

 caseine, from which their blood is formed, strictly 

 speaking, only a certain excess of carbon, which the 

 animal organism cannot possibly employ to produce 

 fibrine or albumen, because the nitrogenised consti- 

 tuents of the food already contain the carbon neces- 

 sary for the production of blood, and because the 

 blood in the body of the carnivora is formed without 

 the aid of this excess of carbon. 



The function performed in the vital process of 

 the graminivora by these substances (sugar, gum, 

 &c.) is indicated in a very clear and convincing 

 manner, when we take into consideration the very 

 small relative amount of the carbon which these 

 animals consume in the nitrogenised constituents of 

 their food, which bears no proportion whatever to 

 the oxygen absorbed through the skin and lungs. 



A horse, for example, can be kept in perfectly 

 good condition, if he obtain as food 15 Ibs. of hay 

 and 4J Ibs. of oats, daily. If we now calculate the 

 whole amount of nitrogen in these matters, as ascer- 

 tained by analysis (1-5 per cent, in the hay, 2'2 per 

 cent, in the oats), (15) in the form of blood, that is, as 

 fibrine and albumen, with the due proportion of water 

 in blood (80 per cent.), the horse receives daily no 

 more than 4^ oz. of nitrogen, corresponding to about 

 8 Ibs. of blood. But along with this nitrogen, that is, 



