146 WHAT DOES MAN LIVE UPON? 



But a skilful agricultural people leads the most judicious 

 life, mingling the nutriment exactly in the same proportions 

 as Nature has mixed it for the suckling in milk. For this 

 contains the nitrogenous nourishment in the caseine, and 

 the material for respiration, in the most accurate propor- 

 tions, in the butter and the sugar of milk. We meet with 

 the other extreme among the nations which, as in the 

 East Indian races, the Negroes and the inhabitants of 

 certain tracts in Europe, live wholly on rice, bananas, 

 potatoes, or similar vegetable substances, in which very 

 little nitrogenous matter exists. Hence the enormous 

 quantity which these nations are forced to take, in order to 

 collect the necessary amount of actual nourishment from 

 the mass of material for respiration. These nations ap- 

 proach those of our domestic animals living wholly upon 

 vegetables and the rest of the vegetable feeders, which pass 

 the whole of their life in feeding and sleeping, and must 

 necessarily consume a great quantity of food, because only 

 a relatively small quantity of actual nutriment is contained 

 in it. Finally, in the Polar regions in general, we find an 

 immoderate consumption of fat inseparably united with the 

 habits of life in these climates. This instinct also is very 

 readily explicable from the foregoing considerations. Here 

 man must produce a greater quantity of heat in order to 

 live, and requires thereto a larger amount of combustible 

 matter, or fuel. For this purpose there could scarcely be 

 any substance so applicable as the fat of animals, which 

 always consists solely of carbon and hydrogen. 



Our investigations have thus led us to recognize that 

 the whole animal world lives upon the vegetable kingdom, 

 either immediately by actual vegetable food, or mediately by 

 the vegetable feeders collecting the peculiar nutritive matters 

 for the carnivora, from the plants, depositing the material 



