GRASSES AND FORAGE PLANTS. 225 



The constituents of plants may be divided into two classes, one class embracing all those 

 substances of which nitrogen or azote forms a part, and the other consisting of non-nitroge 

 nous bodies. Gluten, albumen, gelatine, casein, legumen, and fibrin, belong to the former 

 class, being nitrogenous substances, while starch, gum, sugar, woody fiber, mucilage, etc., are 

 destitute of nitrogen, or non-nitrogenous. 



Only a small quantity of nitrogen is found in vegetable substances, and it is derived, in 

 part, at least, from the atmosphere, in the form of ammonia. On the other hand, nitrogenous 

 substances form a large proportion of the constituents of the blood of animals, and appear in 

 their whole system. As there is a constant wa rte in the animal, and a continual formation of 

 new tissues, as the whole body is constantly renewed through the agency of the blood 

 which is converted into flesh and muscle, there must be a never-failing supply of nourish 

 ment, and this nourishment for the higher animals is found, as already intimated, in the nitro 

 genous elements of plants. 



For every ounce of nitrogen which the animal requires to sustain life 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 which 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 fiber to act mechanically in giving bulk to the food, 

 is not, of course, to be overlooked. 



Nor is this 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 

 nitrogen which any vegetable contains, the smaller will be the quantity 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 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 muscular system 

 develops, and he gains flesh without increasing his fat in proportion. 



The non-nitrogenous substances are necessary for the production of fat to supply the ani 

 mal 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 nutritive 

 values. 



From what has been said, the reader will very readily understand the following tables 

 containing the results of the investigation of Prof. Way. The specimens of the various 

 grasses on which his researches were made, were analyzed both in their green state as taken 

 from the field, and after being dried at a temperature of 212 Fahr., 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 inquiries of Prof. Way were directed to ascertain 



1. The proportion of water in each grass as taken from the field. 



2. The proportion of albuminous or flesh-forming substances, including, without dis 

 tinction, all the nitrogenous principles. 



3. The proportion of oily or fatty matters which may be called fat-forming principles. 



4. The proportion of elements of respiration, or heat-producing principles, among which 

 are included starch, gum, sugar, pectic acid, etc. ; all the non-nitrogenous substances, indeed, 

 except fatty matters and woody fiber. 



