174 THE METHOD OF DARWIN. 



many gradations of structure and function 

 between simple twiners and tendril bearers; 

 (3) the conviction that all such highly special- 

 ized functions and structures are extreme de- 

 velopments of more general but less obvious 

 phenomena, or of slight variations whose source 

 is unknown ; (4) the almost perfectly analogous 

 case of sensitiveness to touch in climbing plants, 

 which is inseparably connected with the power 

 of revolving, and which he had connected with 

 the general though slight sensitiveness of plants 

 observed by Hofmeister; (5) and one of the 

 most important of the data mentioned, the 

 actual case of imperfect and functionless power 

 of revolving in Maurandia semperflorens, which 

 might by a little augmentation become useful 

 in climbing. 



The final verification of the prediction is 

 embodied in the volume on the " Power of 

 Movement in Plants," by Charles and Francis 

 Darwin. The sweeping character of the verifi- 

 cation cannot be better indicated than by quot- 

 ing their own statement of what they intended 

 to show in that volume ; it will serve, too, as a 

 summary of results, for they completely estab- 

 lished what they claimed : " In the course of 

 the present volume it will be shown that ap- 

 parently every growing part of every plant is 



