394 



THE POPULAR SCIENCE MONTHLY. 



sition of the animal food consumed by man. It has been generally 

 assumed that the effect of animal food, in human dietaries, is to in- 

 crease the proportion of the nitrogenous constituents : from the results 

 of these analyses, however, we can not escape the conclusion that the 

 animal elements of a diet, as a whole, increase the proportions of the 

 carbo-hydrates or non-nitrogenous constituents. It appears that two 

 thirds of the nitrogen of the entire body, of the calf and bullocks, was 

 found in the carcass, and of this twelve parts were in the bones, leav- 

 ing fifty-four per cent of the whole nitrogen of the body in the soft 

 parts of the carcass. Of the thirty-three per cent of the nitrogen of 

 the entire body in the offal parts, it was estimated that in the calf 

 seven to eight parts, and in the oxen four to five parts, would be con- 

 sumed as human food. Of the total fat of the body, about seventy 

 per cent in the calf, and rather more than seventy-live per cent in the 

 oxen, were found in the carcass. Of the fat contained in the offal parts, 

 it was estimated that five sixths in the calf and one fifth in the oxen 

 would be consumed as human food. The percentage of the total ni- 

 trogenous and total non-nitrogenous constituents of animals, included 

 in the food of man, has been tabulated by Drs. Lawes and Gilbert as 

 follows : 



According to this estimate, " there would be, in the fat calf ana- 

 lyzed, \\ time, in the fat ox 2| times, in the fat lamb, fat sheep, and 

 fat pig nearly 4| times, and in the very fat sheep 6^ times as much 

 dry fat as dry nitrogenous constituents " in the parts of the animals 

 consumed as human food. As one part of fat is equivalent to two and 

 one half parts of starch, as a source of potential energy which must be 

 taken as the measure of nutritive value, it will be necessary to estimate 

 the fat in its equivalent as starch in making a comparison of vegetable 

 and animal foods with reference to their nutritive value, and the rela- 

 tive ratio of their nitrogenous and non-nitrogenous constituents. On 

 this basis the results of the Rothamsted analyses have been tabulated 

 as follows : 



