VI 



INTRODUCTION 



tion for placing before readers this elementary and necessarily superficial 

 statement of what the living plant is, what it does for us, and how it accom- 

 plishes its good work. 



Where does the living plant obtain all the material that feeds and clothes 

 the innumerable forms of animal life, and finally the hundreds of millions of 

 the human race ? The answer is, mainly from the atmosphere, partly from 

 the sunbeams, and a little from the earth. Collect a large heap of vegetation, 

 and burn it. You will find that all there is left is a thin layer of fine ash r 

 the mineral portion of the plant's materials. The rest has passed off into the 



atmosphere from which 

 it was derived. 



Every blade of grass, 

 every tiniest moss, as 

 well as the more notice- 

 able trees and larger 

 herbs, are doing this 

 work for the animal 

 kingdom ; and there is 

 scarcely an inch of the 

 natural surface of the 

 globe that is not occu- 

 pied by one or other of 

 the vast variety of liv- 

 ing plants that have 

 adapted themselves for 

 life in all situations and 

 under all conditions. It 

 has been computed that 

 no fewer than two hun- 

 dred thousand distinct 

 species of the living 

 plant are known to and 

 have been described 

 and named by man, and 

 it may be taken that 



11 these forms are necessary, in order that full advantage should be 

 taken of all the varying conditions under which life is at all possible. 

 A little warmth, a little moisture, and a little light are the minima of 

 the living plant's demands. At the other end of the scale they may be 

 found in the parched desert, where they must endure extreme heat, 

 extreme light, and almost an absence of moisture. They put in an 

 appearance on the scarcely cooled cinders from the latest volcanic eruption, 

 and thrive in the waters of hot springs having a temperature of 176 F. 



For all these varied conditions a corresponding variety of form and habit 



Denuded of soil by 



FIG. 8. ROOTS OF PINE-TREES. 



d. One of the many exigencies to which the livin" 

 plant is subject. JAPAN. 



