257 



CHAPTEE XII. 

 THE ANIMAL. 



THE body of an animal, from a chemical standpoint, consists 

 of a very intimate mixture of compounds, some of which are 

 little understood and apparently highly complex in character. 

 The body may be considered as made up of lifeless products 

 of metabolism (e.g., fat cells, horny matter, earthy portions of 

 bone, &c.) permeated by the really living substance, proto- 

 plasm. The latter is highly aqueous and contains proteids, 

 with smaller quantities of carbohydrates, fats, and salts. 



The elements contained in the animal body are the same as 

 those found in plants, but their relative proportions differ 

 considerably. Sodium, chlorine, and fluorine particularly ap- 

 pear to be of much more importance to animals than to plants. 



The proximate constituents of animals also resemble those 

 of plants. 



They may be divided into 



(1) Inorganic compounds, consisting mainly of water, 



various acids (e.g., hydrochloric acid), ammonia, 

 and numerous salts (e.g., calcium phosphate, 

 sodium chloride, &c.). 



(2) Organic compounds 



(a) Proteids, e.g., albumin, myosin. 



(b) Amides, e.g., urea. 



(c) Fats. 



(d) Carbohydrates, e.g., glycogen. 



(e) Other compounds. 



The general characteristics of some of these substances have 

 been given in the chapter on the constituents of plants. 

 Reference must be made to some work on physiological 

 chemistry for further details. 



The chemical composition of the whole bodies of animals 

 was investigated by Lawes and Gilbert in 1848-1859.* 



* Jour. Roy. Agric. Soc. 1895. 



