6 Bulletin 81 



portant of these. The white of the egg, the dry lean meat of mus- 

 cle and the casein of milk are albuminoids. The gelatinoids make up 

 the elastic gelatinous part of bones, cartilages, tendons etc. The extractives 

 form the basis of meat extracts, beef teas, etc. The flesh, skin, bones 

 (in part), vital organs, brain, nerves, in fact the bodily mechanism, are made 

 up of protein, diluted, so to speak, with water, supported by the ash of the 

 skeleton and rounded out with fat. It is obvious that protein is of the 

 utmost importance. 



4. Fat is distributed ordinarily all over the body, and comprises from 

 6 to 30 per cent of the live weight in different classes of animals. It consists 

 of carbon, hydrogen and oxygen but contains no nitrogen. While not as 

 vitally necessary to animal life as the other three ingredients, it has much 

 economic interest. 



These various substances are formed from the animal, vegetable and 

 mineral matters known as food, and are converted by the animals eating 

 them, into flesh, fat, bone, milk, wool, and work (energy). 



2. COMPOSITION OF VEGETABLE MATTER 



Since the biblical statement that " all flesh is grass" is scientifically 

 correct, it follows that there is similarity between the constituents of animal 

 and vegetable matter. The groups of ingredients cited under the previous 

 heading — water, ash, protein and fat — are found in feeding stuffs, as are also 

 crude fiber (cellulose, woody tissue) and nitrogen-free extract (starch, 

 sugars, gums, pentosans, etc. ) The individual substances which comprise 

 the groups when they are of vegetable origin are somewhat different from 

 those in the animal body, but these variations are not important to present 

 purposes. 



Water, ash and true fat are quite alike, whether lodged on an animal's 

 frame or in a cornstalk. 



The nitrogenous matters — other than nitrates, alkaloids, etc., which are 

 sometimes present in small quantities — are protein (albuminoids), and 

 amides and allied bodies. The gluten of wheat, which furnishes the dough- 

 making property of flour, is a typical vegetable protein. It exists in con- 

 siderable quantities in seeds and their byproducts. The amides, etc., 

 have less food value than the true protein. They are essentially protein in 

 process of transportation and transition. 



The so-called fat of fodders and feeds is impure, being fat mixed with 

 wax, resins, chlorophyll (the green coloring matter of plants) etc. These 

 ingredients are all extracted from a fodder by boiling ether, hence the 

 term in common usage, ether extract. 



Crudefber, (sometimes called woody fiber or cellulose) makes up the cell 

 walls, the frame- work of the mature plant. Hay and straw, and the hulls of 

 many seeds contain a quarter part or more, while trees consist mainly of 



