22 ' NOURISHMENT OF PLANTS. 



happen during growth ; 2d. That of chemical experi- 

 ment^ by which the constituent elements of plants, 

 their means of sustenance, and some transformations 

 of their substance occurring during growth, have 

 been ascertained. 



From the results arrived at by these researches, 

 a special science, called Vegetable Physiology^ or the 

 knowledge of the vital phenomena, conditions, and 

 laws of plants, has been attained, and of this sci- 

 ence Agricultural Chemistry constitutes a principal 

 division. 



Among the problems connected with practical 

 agriculture which this science has to solve, that 

 more especially relating to the nourishment of plants 

 is of preeminent importance. For it is manifest that 

 if the farmer knew precisely what nutrients would 

 best promote the growth and cultivation of his 

 plants, in what form, quantity, and at what period 

 they must be administered, in order to reap the 

 greatest benefit therefrom, — if he were, moreover, 

 acquainted with the sources from which he could pro- 

 cure them at the cheapest price, — he would be able 

 to make the most extensive, diversified, and profit- 

 able applications of this information in his calling. 

 "Unfortunately, however, science is not so far ma- 

 tured as to be able to furnish certain intelligence 

 upon all these points, but is still compelled in many 

 cases to have recourse to mere conjectures. Never- 

 theless these may prove serviceable, if communicated 

 to the husbandman merely as conjectures^ not as in- 



