34 FEEDING ANIMALS. 



cereals and leguminous seeds which animals eat. They are 

 also found in smaller quantities in grass, clover, hay, and 

 other foods. Without undergoing much change in the 

 animal stomach, they are assimilated and readily converted 

 into blood and thence into muscular fibre. But all these 

 plants which serve as food for animals, contain only a small 

 proportion of albumen, casein, and gluten, and other albu- 

 minoids ; their great bulk is made up of starch, gum, sugar, 

 cellular fibre, and some other carbo-hydrates. They present 

 the animal with a mixture in which the substance of the 

 muscles exists ready-formed ; and for this reason the albu- 

 men, casein, legumen, gluten, and other nitrogenous com- 

 pounds of vegetables were first called flesh-forming princi- 

 ples, or flesh formers. They are now more commonly called 

 albuminoids, or proteids. Careful experiments have shown 

 that no foods which do not contain albuminous compounds 

 can sustain animal life for more than a few days. A sheep, 

 weighing 52 Ibs., being fed on sugar dissolved in water, 

 died in 20 days, and lost 21 Ibs. A goose, weighing 6 Ibs. 

 1 oz., fed on sugar, died in 22 days ; another, fed on starch, 

 lived 27 days. Dogs fed on starch, sugar, gum, butter, and 

 other food perfectly free from albuminoids, apparently keep 

 their condition the first week, then rapidly become emaci- 

 ated, and die at about the end of the fifth week, only a 

 little later than if no food had been given them. It has 

 also been found that animals cannot live upon albuminoids 

 alone. But foods rich in albuminoids have a great superi- 

 ority in feeding value. 



NON-NITROGENOUS NUTRIENTS. 



CAKBO-HYDRATES. As we have seen, the great bulk of 

 vegetables is made up of non-nitrogenous compounds 

 called carbo-hydrates. The principal of these are cellulose, 

 a woody fibre, starch, dextrine, cane, grape and fruit sugar, 

 and the gums. They are called carbo-hydrates because 



