CHAPTEE IV. 



SKETCH OF THE THEORY OF FOOD AND NUTRITION. 



Composition of the body — Waste of tissue — Repair of waste — Analysis 

 of forage — Analysis of the ash of various plants and seeds — 

 Nitrogenous food — Fat, starch, and sugar in food — Heat supply — 

 Mineral substances — Husk of grain — Bulk in food — Selection of 

 food — Hay and grass — Green meat — Variety in food — Salt — 

 Relations of cold, heat, and clothing to food — Mastication and 

 digestion — Functions performed by the blood — Appetite — Influence 

 of an artificial state of life — Preparation of food. 



Composition of the Body. — Nearly four-fifths of tlie 

 body of the horse is composed of water, the remainder 

 being made up of various organic and inorganic compounds. 

 The former may be subdivided into substances containing 

 nitrogen — a gas, which when mixed with oxygen, from 

 atmospheric air — and substances which are wanting in 

 that element. The latter comprise the different mineral 

 matters of the system, such as common salt, the carbonate 

 and phosphate of lime, and carbonic acid, with traces of 

 ammonia. The non-nitrogenous compounds may be put 

 under two classes ; namely, fats, and saccharine substances, 

 such as milk and sugar. 



Every tissue of the body which is employed in the 

 performance of labour — such as the muscles, tendons, 



