LEAVES ON THE ATMOSPHERE. £17 



ingly simple an organ as the leaf of a plant. 

 The agency of the vital principle alone can 

 account for these wonders, though it cannot, 

 to our understanding, explain them. " The 

 thickest veil," says Dr. Thomson at the end 

 of his chapter on vegetation, " covers the 

 whole of these processes ; and so far have 

 philosophers hitherto been from removing 

 this veil, that they have not even been able 

 to approach it. All these operations, indeed, 

 are evidently chemical decompositions and 

 combinations ; but we neither know what 

 these decompositions and combinations are, 

 nor the instruments in which they take 

 place, nor the agents by which they are regu- 

 lated/' 



The vain Buffon caused his own statue to 

 be inscribed " a genius equal to the majesty 

 of nature,* but a blade of grass was sufficient 

 to confound his pretensions, 



