CHAP. III.] PROTECTIVE ARRANOEMENTS. 113 



(2.) Protection against living enemies. The modifi- 

 cations uhdergone by plants necessitated by climatic 

 influence are not more varied than those required to 

 combat successfully the attacks of living enemies, and 

 the diflBculty in the latter case is intensified by the fact 

 that, being possessed of life, and consequently possess- 

 ing the power of modification or adaptation to circum- 

 stances it follows that when a plant has evolved an 

 arrangement to ward off the attacks of its special enemy, 

 the latter in turn changes its tactics, and by a similar 

 modification often successfully overcomes the obstacle 

 placed in its way. There is no evidence in support of 

 the view that plants or animals were specially created to 

 serve as food for their neighbours, and wherever this 

 happens it always resolves itself into the condition of the 

 victim being overcome by the superior physical or 

 mental power of the victor. Man's mental development 

 has placed numerous members of both the plant and 

 animal kingdoms under his control, and this sphere of 

 influence has gone on increasing with the development 

 of that power. The same ideas are true of groups of 

 plants ; the forest tree type of vegetation with the 

 massive trunk and spreading branches at one time bid 

 fair to become the dominant race, but the sheer strength 

 method on which they depended has been superseded by 

 the greater adaptivity and more especially the greater 

 susceptibility of the protoplasm to external agents, in 

 the smaller members of the Vegetable Kingdom, and 

 many of these latter are now utilizing the trunks of the 

 older type as a means of support ; in some instances 

 strangulation of the trunk is effected by the modern 

 twiner, as in the honeysuckle, or is compelled by the 



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