PAET THIRD. 



APPLICATION OF THE THEOEY OF NUTRITION TO 

 PRACTICAL USE IN THE FARM. 



IN every case in which life is concerned, it is not at once to be 

 concluded that, so much material being consumed, there will 

 be uniformly and necessarily so much product. This kind of 

 conclusion is not indeed absolutely permitted even in those 

 departments of production in which the materials and the 

 results are wholly inert. In the case of manufactures, wherein 

 the raw materials and the results are alike destitute of physio- 

 logical character or of a living agency, the failure of perfect 

 uniformity in successive effects is readily understood, when the 

 attention turns to the well-known varieties in the purity of 

 raw materials met with in the market respectively under one 

 name, and again to the more or less perfect adjustment, under 

 different circumstances, of the manipulations prescribed in the 

 processes concerned. But it is not at first easy to realise the 

 idea that the nutrition of animals presents a manifest parallel- 

 ism to the manufacture of complex chemical substances out of 

 materials existing in nature. And when the idea is once 

 thoroughly apprehended, it is somewhat difficult to avoid run- 

 ning into the opposite extreme, and picturing that in the 

 mind as an identity of things which is really only a parallelism. 

 It is doubtless true that the results, whether of an inert clienri- 



2H 



