4 KUtRITIQN OF FARM ANIMALS 



X Organic matter. By the action of oxygen at a high tem- 

 perature, the dry matter of plants or animals may be separated 

 into two portions, one being converted into the gaseous state, 

 while the other remains behind in the solid form. Following 

 the older nomenclature, it is customary to distinguish these 

 two portions as " organic " and " inorganic," or " ash," in- 

 gredients. The terms, however, are to some extent misnomers, 

 since no such sharp distinction exists as was once supposed 

 between organic and inorganic compounds. Organic matter 

 in the sense in which the term is commonly used may be said 

 to be broadly equivalent to the carbon compounds of the organ- 

 ism, but even this definition is inexact and the same element 

 may be volatilized during oxidation or may appear in the ash 

 according to circumstances. 



For example, the element sulphur is an essential ingredient 

 of the proteins. When these are burned in air part of the 

 sulphur escapes in the gaseous form, but a part also combines 

 with any bases present and appears in the ash as sulphates. 

 Even the element carbon, distinctive of so-called organic matter, 

 may appear in part in the ash of the plant or animal in the form of 

 carbonates when the bases of the ash are in excess of the acid 

 radicles. These examples serve to show that an element may 

 be an integral part of the molecules which make up the organic 

 matter and yet appear after incineration in the ash. Thus it 

 has recently been shown that the phosphorus of wheat bran 

 and other feeding stuffs is present chiefly in the form of a 

 complex carbon compound, yet when these materials are burned 

 the phosphorus appears in the ash in the form of phosphates. 



Organic matter is usually regarded as consisting of the ele- 

 ments carbon, hydrogen, oxygen, nitrogen and sulphur, phos- 

 phorus being sometimes added to the list, but doubtless other 

 elements like potassium, sodium, chlorin, etc., also enter into 

 the structure of the " organic " molecules. 



4. Subdivision of organic matter. The number of individ- 

 ual organic compounds found in the animal body or in the plant 

 is very great. For the present purpose, however, it is not 

 necessary to consider separately each individual substance but 

 only the general properties of the important groups into which 

 they may be classified. 



The organic constituents of the body may be subdivided into 



