Classification of Feeding Principles. 7 



starch, and a third weighing 5 Ibs. 12 oz. with gum : the latter 

 died even after 16 days, and was then found to weigh 4 Ibs. 

 12 oz. ; and the former after 27 days, when its weight amounted 

 to only G^lbs. 



Practical experience, moreover, has made us acquainted with 

 the high feeding value of oilcake, beans, and grain, articles of 

 food very rich in albuminous compounds, and with the inferiority 

 of food poor in nitrogenized compounds. It may therefore be 

 laid down as a principle established both by practice and 

 science, that the nutritive value of food depends in a great 

 measure upon the amount of albuminous compounds which it 

 contains. 



Non-Nitrogenized Principles. Neither the health nor indeed 

 the life of all our domesticated animals, we have seen, can be 

 maintained by food destitute of nitrogenized or flesh-producing 

 matters. Though absolutely necessary to the very existence of 

 animal life, long experience and direct experiments have proved 

 alike that food consisting entirely of muscle-producing matters 

 cannot support the life of herbivorous animals for any length of 

 time. Thus a goose, it has been found by experiment, when fed 

 with albumen or white of egg, died after 46 days, her original 

 weight of 8 Ibs. 1 oz. having sunk to 4i Ibs. Similar experi- 

 ments have shown that herbivorous animals, when fed upon 

 nitrogenized food, containing no starch, sugar, or other non- 

 nitrogenized compound, notwithstanding the liberal supply of 

 the highly nutritive albuminous matters, become emaciated, and 

 die almost as soon as others fed upon food containing no 

 nitrogen at all. Experience thus teaches that starch, fat, sugar, 

 gum, and other organic compounds not containing nitrogen, are 

 almost as essential to the well-being of herbivorous animals as 

 the flesh-forming principles. 



The various non-nitrogenized substances are all characterized 

 by a large proportion of carbon, for which reason they are some- 

 times called carbonaceous constituents of food. Their use in 

 the animal economy is of a two-fold character. They supply 

 either the materials for the formation of animal fat, or they are 

 employed to support respiration, and with it animal heat. Ac- 

 cording to the fitness and ease with which the non~nitrogenized 

 compounds fulfil the one or the other function, they may be 

 divided into two classes, namely, into fat-producing matters and 

 into principles of respiration. To the first belong the fatty and 

 oily matters which occur in all our cultivated plants, in some in 

 larger, in others in smaller quantities. The oily and fatty vegetable 

 substances are eminently well adapted to the laying on of fat in 

 animals, inasmuch as the composition of vegetable fat is analo- 



