NUTRITIVE VALUE. 115. 



For every ounce of nitrogen which the animal requires to 

 sustain lilc and health, he must take into the stomach, in the 

 shape of food, such a quantity of vegetable substances as will 

 furnish him with an ounce of nitrogen. If we suppose one 

 kind of hay to contain one ounce of nitrogen to the pound, and 

 another to have only half as much, or only an ounce in two 

 pounds, the pound wliich contains the ounce of nitrogen would 

 go as far to nourish the animal — other things being equal — 

 as the two pounds which contain only the same quantity of 

 nitrogen. The importance of woody fibre to act mechanically 

 in giving bulk to the food, is not, of course, to be overlooked. 



Nor is tins a mere deduction of theory. The experiment has 

 frequently been made, and it is now fully established both by 

 science and experience, that the greater the proportion of nitro- 

 gen wliich any vegetable contains, the smaller will be the quan- 

 tity of that vegetable required to nourish the animal body, and 

 the less nitrogen any vegetable contains, the greater will be the 

 quantity of it required. Muscle and flesh are composed of 

 nitrogenous principles, while fat is made up of ndn-nitrogenous 

 matter. Every keeper of stock knows that to feed an animal 

 on oil cake alone, for instance, which is but slightly nitroge- 

 nous, might fatten him, but it would not give him strength of 

 muscle or size ; while if the same animal be kept on the cereal 

 grains, as wheat or Indian corn, alone, his size rapidly increases, 

 his muscular system develops, and he gains flesh without 

 increasing his fat in proportion. It was with reference to these 

 facts that Boussingault formed his tables of nutritive equiva- 

 lents, and they agree very closely with the results of practical 

 observation. 



The non-nitrogenous substances are necessary for the pro- 

 duction of fat and to supply tlie animal body with heat, and 

 thus they meet a want in the animal economy, although they 

 do not contribute so directly to nourish and sustain the system. 

 They are, therefore, important in the analyses of articles of 

 food, though not so essential in determining merely their nutri- 

 tive values. 



From what has been said, the reader will very readily 

 understand the following tables containing the results of the 

 investigations of Prof. Way. The specimens of the various 

 grasses on which his researches were made, were analyzed both 



