I.] EVOLUTION OF THE ROOT. 41 



of democratic society. Seen from above, their mingled 

 tops spread in a sea of verdure basking in light; seen 

 from below, all is shadow, through which spots of timid 

 sunshine steal down among legions of dark, mossy 

 trunks, toadstools and rank ferns, protruding roots, 

 matted bushes, and rotting carcasses of fallen trees. A 

 generation ago one might find here and there the rugged 

 trunk of some great pine lifting its verdant spire above 

 the indistinguished myriads of the forest. The woods 

 of Maine had their aristocracy; but the axe of the wood- 

 man has laid them low, and these lords of the wilderness 

 are seen no more." 



In such bold and generalized examples as this, the 

 student is able to discern only the general fact of pro- 

 gressive divergency and general adaptation to conditions, 

 without being able to discover the particular directive 

 forces which have been at the bottom of the evolution. 

 It is only when one considers a specific example that he 

 can arrive at any just conclusions respecting initial 

 causes of modification. Of adaptive modifications, two 

 general classes have been responsible for the ascent of 

 the vegetable kingdom; one a mere moulding or shaping 

 into the passive physical environments, the other the 

 direct result of stress or strain imposed upon the organ- 

 ism by wind and water, and by the necessities of a 

 radical change of habit from aquatic to terrestrial life, 

 and later on by the stimuli of insects upon the flowers. 

 One of the very best examples of the mere passive ascent 

 is afforded by the evolution of the root as a feeding 

 organ; and a like example of development as a result of 

 strain is afforded by the evolution of the stem and vas- 

 cular or fibrous system. Our present flora, like our pres- 

 ent fauna, is an evolution from aquatic life. The first 



