EXPERIMENTS WITH DIFFERENT FOODS. 259 



the Academies of France and Amsterdam were equally 

 conclusive that gelatin alone soon ceases to be nutritive. 



Mr. Savory's observations on food confirm and extend 

 the results obtained by Magendie, Chossat, and others. 

 They show that animals fed exclusively on non- nitrogenous 

 diet speedily emaciate and die, as if from starvation ; that 

 a much larger amount of urine is voided by those fed with 

 nitrogenous than by those with non-nitrogenous food ; and 

 that animal heat is maintained as well by the former as by 

 the latter a fact which seems to prove that nitrogenous 

 elements of food, as well as non -nitrogenous, may be 

 regarded as calorifacient. The non -nitrogenous principles, 

 however, he believes to be calorifacient essentially, not 

 being first converted into tissue : but of the nitrogenous, 

 he believes that only a part is thus directly calorifacient, 

 the rest being employed in the formation of tissue. Con- 

 trary to the views of Liebig and Lehmann, Savory has 

 shown that, while animals speedily die when confined to 

 non-nitrogenous diet, they may live long when fed exclu- 

 sively with nitrogenous food. 



Man is supported as well by food constituted wholly of 

 animal substances, as by that which is formed entirely of 

 vegetable matters, on the condition, of course, that it 

 contain a mixture of the various nitrogenous and non- 

 nitrogenous substances just shown to be essential for 

 healthy nutrition. In the case of carnivorous animals, the 

 food upon which they exist, consisting as it does of the 

 flesh and blood of other animals, not only contains all the 

 elements of which their own blood and tissues are composed, 

 but contains them combined, probably, in the same forms. 

 Therefore, little more may seem requisite, in the prepara- 

 tion of this kind of food for the nutrition of the body, than 

 that it should be dissolved and conveyed into the blood in 

 a condition capable of being re- organized. But in the 

 case of the herbivorous animals, which feed exclusively 

 upon vegetable substances, it might seem as if there would 



