400 The Movements of Plants 



are dissimilar in the two cases. We must come back, in fact, to 

 Darwin's comparison of plants to animals. In both there is per- 

 ceptive machinery by which they are made delicately alive to their 

 environment, in both the existing survivors are those whose internal 

 constitution has enabled them to respond in a beneficial way to the 

 disturbance originating in their sense-organs. 



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