THE SLEEP OF PLANTS
201
Bose was officially informed that 'the palm tree was dead, and that its movements had ceased.'
Further experiments enabled Bose to show that movements similar to that of the palm tree occur in all
Fig. 25.—Records of the daily movement of the Palm Tree, of Tropaeolum, and of the Palm Leaf. The upper record gives the daily variation of temperature.
trees and their branches and leaves.[1] He was further able to trace the cause of the movement to the joint effects of geotropism and temperature; he designates the new phenomenon as thermo-geotropism. Under the action of the stimulus of gravity stems, branches and leaves tend to erect themselves against the force of gravity, and a
- ↑ Trans. Bose Inst., vol. i., 1918.
