110 THE CHEMISTRY OF THE FARM. 



the manure will be the same as that contained in the food 

 consumed ; the albuminoids and ash constituents of the 

 food used for the renovation of tissue being in this case 

 equivalent to the quantity yielded by the degradation of 

 tissue. In cases where the body weight is increasing, or 

 milk is being produced, the amount of nitrogen and ash 

 constituents in the manure will be less than that in the 

 food in direct proportion to the quantity of these substances 

 which has been converted into animal produce. 



A part of the albuminoids and ash constituents is left 

 undigested during the passage of the food through the 

 alimentary canal ; these are voided in the solid excrement. 

 The digested nitrogenous matter and ash constituents 

 pass into the^blood, a part of them may be converted into 

 animal increase if the animal is gaining in weight or pro- 

 ducing milk, and the remainder is finally separated from 

 the blood by the kidneys, and is voided in the form of 

 urine. The albuminoids and amides are oxidised into urea 

 before being expelled from the system. In the case of 

 herbivorous animals hippuric acid is also formed in vari- 

 al^le quantities, and is found as an ingredient of the 

 urine. 



The proportion of the nitrogen in the food which will 

 appear in the solid excrement is determined by the diges- 

 tion coefficient of the albuminoids. Thus 79 has been 

 already given as the digestion coefficient of the albumi- 

 noids of barley meal when consumed by a pig ; it follows 

 that in this case for 100 of albuminoids consumed 21 will 

 be voided in the solid excrement, and 79 pass into the 

 blood. It has been already stated that 500 lb. of barley 

 meal, containing about 53 lb. of albuminoids, w^ill in the 

 case of the pig produce 100 lb. of animal increase, con- 



