DAIRY PRODUCTS. 313 



animal heat, and resembles closely, in its mode of action, the 

 well-known process of combustion. Among its final results, 

 most important is a vast amount of carbonic acid and water, 

 which are also the results of the artificial combustion of starch, 

 sugar, fat and similarly constituted articles, under the influence 

 of a sufficient amount of oxygen, the active portion of air. Sub- 

 stances like starch, sugar, gums, cellulose, fats and oils of every 

 description, in fact all such substances as consist of carbon and 

 hydrogen, with or without oxygen, and which are known to 

 chemists as carbo-hydrates and hydro-carbons (with but a few 

 exceptions), are capable of supporting the process of respi- 

 ration. 



Fourth. — The process of nutrition consists mainly in the 

 building up of bone and muscle during the period of growth, 

 and the replacement of the tissues which have been wasted in 

 the support of the mechanical force exerted. A successful 

 nutrition depends on the consumption of such nitrogenous sub- 

 stances as are known by the collective name of albuminous 

 compounds. These albuminoids are supposed to be formed 

 originally in every case within the vegetable organism. Vege- 

 table albumen (the gluten of the seeds of our cultivated cereals), 

 and the vegetable casein, the legumen of the seeds of the Legu- 

 ininosa?), are some of their most important representatives. 

 Plants are therefore looked upon as the natural resource from 

 which the animal kingdom, directly or indirectly, draws its 

 requisite supply of nitrogenous matter for the formation of blood 

 and its subsequent deposition of animal tissues, bones, muscles 

 and fat. As a general rule, it must be conceded that they are 

 of particular importance, as far as a successful nutrition is con- 

 cerned, in their soluble modification, for in that condition they 

 are more apt to be directly convertible without particular exer- 

 tion of the apparatus of digestion. 



Fifth. — Certain mineral substances, the phosphates, chlorides, 

 sulphates and carbonates of both alkalies and alkaline earths, 

 besides the oxides of iron and traces of manganese, silica and 

 fluorine are essential to the general promotion of animal life. 

 They are supplied by the mineral constituents of our articles of 

 food. Foremost among these mineral constituents are the 

 phosphates of lime, soda, potassa and magnesia, the chlorides of 

 sodium and potassium, the sulphates of soda and potassa, and 



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