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CHAPTER XL 



THE ' POWER OF MOVEMENT IN PLANTS.' l88o. 



[THE few sentences in the autobiographical chapter give with 

 sufficient clearness the connection between the 'Power of 

 Movement/ and one of the author's earlier books, that on 

 1 Climbing Plants.' The central idea of the book is that the 

 movements of plants in relation to light, gravitation, &c, 

 are modifications of a spontaneous tendency to revolve or 

 circumnutate, which is widely inherent in the growing parts 

 of plants. This conception has not been generally adopted, 

 and has not taken a place among the canons of orthodox 

 physiology. The book has been treated by Professor Sachs 

 with a few words of professorial contempt ; and by Professor 

 Wiesner it has been honoured by careful and generously 

 expressed criticism. 



Mr. Thiselton Dyer * has well said : " Whether this masterly 

 conception of the unity of what has hitherto seemed a chaos of 

 unrelated phenomena will be sustained, time alone will show. 

 But no one can doubt the importance of what Mr. Darwin 

 has done, in showing that for the future the phenomena of 

 plant movement can and indeed must be studied from a 

 single point of view." 



The work was begun in the summer of 1877, after the 

 publication of ' Different Forms of Flowers,' and by the 

 autumn his enthusiasm for the subject was thoroughly estab- 

 lished, and he wrote to Mr. Dyer : "I am all on fire at the 



* ' Charles Darwin ' (' Nature' Series), p. 41. 



