14 STRUCTURE AND FUNCTIONS 



food and liquid of some kind are the essentials 

 necessary for the sustenance of animal life, and 

 should but one of these be wanting, although 

 the other two may be supplied in excess, death 

 will ensue. So it is with plants; certain con- 

 ditions are necessary to bring them to maturity, 

 and those of each genus require a peculiar 

 treatment to bring them to perfection; and it is 

 the study of these peculiar conditions and the 

 successful application of various manures to 

 forward the development of the different organs, 

 or the application of other substances to neu- 

 tralize any quality in a peculiar soil, which 

 would be prejudicial to the growth of a certain 

 crop, which constitutes agricultural chemistry 

 in its widest and most extended sense. 



As a general rule, all plants consist of a root, 

 stem, and leaves, and these organs again have 

 a direct and distinct reference to the production 

 of a fruit, the which being accomplished, the 

 plant either dies entirely or lies torpid for a 

 season, until a succession of the same circum- 

 stances which gave it life in the first instance, 

 shall again call its productive organs into 

 action. 



The root of a plant performs the two impor- 

 tant offices of retaining it in a fixed position and 

 of supplying it with a great part of its nourish- 

 ment, and it may therefore be considered as 

 analogous in some measure to the mouth and 

 limbs of an animal. 



It is not at all necessary in this place to con- 

 sider the different forms the root assumes in 

 different plants, it is sufficient for our purpose 



