146 THE ART OF CULTURE. 



the straw as will enable it to bear the weight of the 

 ears. 



We must proceed in the culture of plants in pre- 

 cisely 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; all domestic ani- 

 mals, for example, contain much fat. We give food 

 to animals, 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 conditions necessary to 

 effect this purpose in birds are diff'erent from those 

 in quadrupeds ; and it is well known that charcoal 

 powder produces such an excessive growth of the 

 liver of a goose, as at length causes the death of the 

 animal. 



The increase or diminution of the vital activity of 

 vegetables depends only on heat and solar light, 

 which we have not arbitrarily at our disposal : all 

 that we can do is to supply those substances which are 

 adapted for assimilation by the power already present 

 in the organs of the plant. But what then are these 

 substances ? They may easily be detected by the ex- 

 amination of a soil, which is always fertile in given 

 eosmical and atmospheric conditions ; for it is evi- 

 dent, that the knowledge of its state and compo- 

 sition must enable us to discover the circumstances 

 under which a sterile soil may be rendered fertile. 

 It is the duty of the chemist to explain the com- 

 position of a fertile soil, but the discovery of its 

 proper state or condition belongs to the agricul- 

 turist ; 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 component parts. Sand, clay, and 



