FAT-POEMING SUBSTANCES. 221 



pies, while fat is made up, to a great extent, of non- 

 nitrogenous matter. Every keeper of stock knows that 

 to feed an animal on oil-cake alone, for instance, which 

 is but slightly nitrogenous, 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 mus- 

 cular system develops, and he gains flesh without in- 

 creasing his fat in proportion. These substances are 

 usually given, therefore, as a part of the regular feed, 

 only, or in connection with other and bulkier substances, 

 as hay. It was with reference to these facts that Boussin- 

 gault formed his tables of nutritive equivalents, and 

 they agree very closely with the results of practical 

 observation. 



The non-nitrogenous substances are equally necessary 

 for the production of fat, and to supply the animal 

 body with heat ; and thus they meet a want in the animal 

 economy, although they do not, according to chemical 

 investigations, contribute so directly to nourish and 

 sustain the system. They are, therefore, important 

 in the analyses of articles of food, though not so essen- 

 tial in determining merely their nutritive values. 



Prom what has been said, the reader will very readily 

 understand the following tables, containing the results 

 of the investigations of Professor Way. The specimens 

 of the various grasses, on which his researches were 

 made, were analyzed both in their green state as taken 

 fi'om the field, and after being dried at a temperature 

 of 212° Pahr., a point at which the moisture is found to 

 be entirely expelled, and evaporation ceases, and the 

 importance of both determinations must be obvious on 

 a moment's reflection. 



The names of the natural grasses, and the dates of 

 their collection, are arranged in the following table : 

 19* 



