ON THE FOOD OF PLANTS. 115 



buried in their green state,- what powerful effects 

 could they have been expected to have produced 

 in fertilising the soil, more than the severed ra- 

 dicals of other plants, of which the earth is 

 always full ? Surely none. Then what created 

 the difference ? Most evidently the exposure 

 to heat and air on the kiln, which, by oxydise- 

 ment, created the sugar. 



Vegetable substances and dung, in drying, un- 

 doubtedly are reduced in weight, by the eva- 

 poration of its water; but this is a loss of no 

 importance, for water is again readily supplied, 

 and by the operation they absorb oxygene, and 

 are thus brought to a state much more efficient ; 

 that of soluble oxydes. From all the observ- 

 ations I have made, and which I have endea- 

 voured to explain, I am convinced, that every 

 addition of food to plants, and every operation 

 of agriculture, wherein the cultivation of vege- 

 tables is concerned ; will be found more or less 

 efficacious as it favours the free access, or in- 

 gress and egress, and the general influence, of 

 the oxygene of the atmosphere and water, to the 

 whole structure of the plant, and the ingredients 

 of its food during preparation. 



And as to the mechanical effect of dung, in 

 pulverising the soil ; that which is placed on the 

 surface, must ultimately be equal to thai which 



