MOVEMENT IN PLANTS. 197 



round which to twine." The stem of the plant 

 is not in the least twisted by this movement. 

 Nearly all of the great divisions of twining plants, 

 leaf-climbers, and tendril-bearers "have the same 

 remarkable power of spontaneously revolving." 



" The Power of Movements in Plants " was 

 published on November 6th, 1880. It embodies a 

 vast amount of work carried on in conjunction with 

 Francis Darwin. This volume bears a very direct 

 relation to that last mentioned, as Darwin has ex- 

 plained in his Autobiography : — 



" In accordance with the principle of evolution it was im- 

 possible to account for climbing plants having been developed 

 in so many widely different groups unless all kinds of plants 

 possess some slight power of movement of an analogous kind. 

 This I proved to be the case ; and I was further led to a rather 

 wide generalisation, viz. that the great and important classes 

 of movements, excited by light, the attraction of gravity, &c., 

 are all modified forms of the fundamental movement of circum- 

 nutation." 



An extreme example of circumnutation has already 

 been described in the revolving movements of the 

 youngest parts of the stem of a twining plant. 



The work evoked very great interest in this 

 country, but was severely criticised by certain German 

 botanists. The immense number of new observations 

 must always have a very high value, whatever be the 

 fate of the general conclusions, concerning which it 

 may be remarked that Darwin's conclusions have 

 often been criticised before, but time has shown that 

 he was right. 



