MAlSUxiL OF CATTLE-I^^EPBING. 13 



It is evident from tliese figures tliat in all calculations 

 regarding tlie gain or loss of fat by the body, we may treat 

 this fat, in spite of tlie numerous modifications wliich it 

 undergoes in tlie various organs, as chemically identical, 

 without falling into any appreciable error. 



The quantity of fat which may be laid up in the body 

 is often enormous. For example, in the case of fattened 

 neat-cattle and swine, the fat may make up from 25 to 

 over 40 per cent, of the live weight of these animals, or 

 from two to three times as much as all the nitrogenous 

 substances present. In lean animals, on the other hand, 

 the amount of fat is much less, and that of the nitro- 

 genous substances relatively greater. 



Other Non-Nitrogenous Organic Substances. — ^All 

 the non-nitrogenous organic substances, other than fat, 

 which occur in the body, and are to be regarded as normal 

 constituents of it, are very inconsiderable in quantity, al- 

 though often of importance for the functions of the organs 

 or fluids in which they are found. 



The gastric juice (the digestive fluid of the stomach), 

 and also the contents of the large and small intestines, and 

 sometimes the chyle of the thoracic duct (see p, ^S\ con- 

 tain lactio acid^ the well-known acid of sour milk, while 

 the juices of the flesh contain another o.ddi—sar'kolaMiG 

 ad(l-Amm.Qri(S^ with the former. 



The blood, and in fact almost all the animal fluids, also 

 contain minute quantities of one or the other of these 

 acids- 



Sugar is likewise found in the blood, but at most in 

 quantities not exceeding 0.015 per cent., except in the 



* Two substances are said to be isomeric when tbey baye the same 

 percentage composition, but different cbemical propeities. 



