SUMMARY 235 



temperature being often quickly followed by a correspond- 

 ing movement of the tree. 



Anisotropy induced by previous geotropic stimulation 

 appears to be a contributory factor in the striking mani- 

 festation of diurnal movement. For it appears that the 

 greater the incHnation of the tree to the vertical, the greater 

 is the extent of its periodic movement under variation of 

 temperature. 



