OBJECTS OF AGRICULTURE. 10d 



development and production of certain parts of plants, or of 

 certain vegetable matters, employed as food for man and animals, 

 or for the purposes of industry. 



1 He means employed vary according to the objects which it 

 is desired to attain. Thus, the mode of culture employed for 

 the purpose of procuring fine pliable straw for Tuscan hats, is 

 the very opposite to that which must be adopted in order to pro- 

 duce a maximum of corn from the same plant. Peculiar 

 methods must be used for the production of nitrogen in the 

 seeds, others for giving strength and solidity to the straw, and 

 others again must be followed when we wish to give such 

 strength and solidity to the straw as will enable it to bear the 

 weight of the ears. 



We must proceed in the culture of plants in precisely the 

 same manner as we do in the fattening of animals. The flesh 

 of the stag and roe, or of wild animals in general, is quite devoid 

 of fat, like the muscular flesh of the Arab; or it contains only 

 small quantities of it. The production of flesh and fat may be 

 artificially increased ; for all domestic animals become fat. We 

 give to animals food which increases the activity of certain organs, 

 and is itself capable of being transformed into fat. We add to 

 the quantity of food, or we lessen the processes of respiration 

 and perspiration by preventing motion. 



The increase or diminution of the vital activity of vegetables 

 depends only on heat and solar light, which we have not arbitra- 

 rily at our disposal : all that we can do is to supply substances 

 adapted for assimilation by the power already present in the or- 

 gans of the plant. But what then are these substances ? They 

 may easily be detected by the examination of a soil always fer- 

 tile in the existing cosmical and atmospheric conditions ; for it 

 is evident that the knowledge of its state and composition must 

 enable us to discover the conditions under which such a soil is 

 rendered fertile. It is the duty of the chemist to explain the 

 composition of a fertile soil, but the discovery of its proper phy- 

 sical state or condition belongs to the agriculturist j our present 

 business lies only with the former. 



Arable land is originally formed by the crumbling of rocks, 

 and its properties depend on the nature of their principal compo- 



