

CHAPTER II. 



NUTRITION. 



24. 



THE general structure and properties of 

 Vegetable tissue having been explained, 

 it becomes desirable briefly to describe the or- 

 gans by which plants are nourished, and enabled 

 to perform the functions of growth and secre- 

 tion, as the physiology of this part of the sub- 

 ject, which is in fact, nothing more than the 

 active agency of those organs, cannot be well 

 understood without some distinct idea of their 

 form and nature. 



The organs which are indispensable to the 

 nutrition of all vascular plants, are three, i. e. 

 the Root, the Stem or Trunk, and the Leaves. 

 In cellular plants these are often so united that 

 the parts are scarcely distinguishable. It will 

 be desirable to consider them in detail as they 

 are found in vascular plants, in which they are 

 generally well defined. 



25. -The Root (radix). This terra is com- 



