202 DIGESTION. 



exclusively on rice. But it is not only the non-nitrogenous 

 substances, which, taken alone, are insufficient for the mainte- 

 nance of health. The experiments of 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 proves that nitrogenous elements of food, as well as non- 

 nitrogenous, may be regarded as calorifacient. The non-nitro- 

 genous principles, however, he believes to be calorifacient es- 

 sentially, not being first converted into tissue; but of the 

 nitrogenous, he believes that only a part is thus directly cal- 

 orifacient, the rest being employed in the formation of tissue. 

 Contrary 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 exclusively with 

 nitrogenous food. 



Man is supported as well by food constituted wholly of ani- 

 mal substances, as by that which is formed entirely of vegeta- 

 ble matters, on the condition, of course, that it contain a mix- 

 ture 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, con- 

 sisting as it does of the flesh and blood of other animals, not 

 onjy 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 preparation 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 reorganized. But in 

 the case of the herbivorous animals, which feed exclusively 

 upon vegetable substances, it might seem as if there would be 

 greater difficulty in procuring food capable of assimilation 

 into their blood and tissues. But the chief ordinary articles 

 of vegetable food contain substances identical in composition 

 with the albumen, fibrin, and casein, which constitute the 

 principal nutritive materials in animal food. Albumen is 

 abundant in the juices and seeds of nearly all vegetables ; the 

 gluten which exists, especially in corn and other seeds of 

 grasses as well as in their juices, is identical in composition 

 with fibrin, and is often named vegetable fibrin ; and the sub- 



