ANIMAL AND VEGETABLE FOOD. 919 



afford as much nitrogen as 4 Ibs. of lean fresh 

 meat, allowing both to contain 75 per cent, of 

 water. And as it requires 100 Ibs. of fresh tur- 

 nips to afford 8-8 Ibs. of dry solid matter, which 

 contains 2*2 per cent, of nitrogen, nearly 84 Ibs. 

 would be required to afford as much nitrogenized 

 matter as 1 Ib. of dry fibrin, albumen, or caseine.* 

 Again, so far is it from being true, that man 

 and other animals require less food in proportion 

 as it abounds with nitrogen, that a much larger 

 amount of lean fresh meat is required than of 

 wheat, barley, or any other farinaceous aliments, 

 as we have already seen with regard to carnivora 

 and herbivora. We have also seen that the 

 hunters of America consume daily about 8 Ibs. of 

 fresh meat, when they have no other food ; while 

 it is certain that the labouring classes of Europe 

 are equally well supported on 24 oz. of flour made 

 into bread, with 8 oz. of fat bacon, that the 



* If then it be a fact, that lean fresh meat contains 4-25 per 

 cent, of nitrogen, while the purely farinaceous matter of grain, 

 potatoes, and turnips, contains only from 1-39 to 2-30 per cent, 

 of that element, how is it possible that herbivorous animals can 

 exhale more nitrogen than such as are carnivorous ? For we have 

 seen that the latter consume a larger amount of food in a given 

 time, in proportion to their weight ; and that the same amount of 

 nitrogen enters into the composition of both classes. It therefore 

 follows, that all granivorous animals, and a large majority of the 

 human race, who live chiefly on vegetable aliments, must derive 

 a portion of their nitrogen by respiration, or by swallowing it with 

 their food in the form of air. It cannot then be admitted, that 

 their food contains all the nitrogen found in their excretions. 



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