SUMMARY 249 



of the Kentia Palm. Record i is of diurnal variation of 

 temperature ; record 2 is the normal diurnal record of 

 the movement of the leaf ; record 3 was taken of the 

 same leaf after the plant and all its leaves had been thickly 

 coated with vaseline. The abolition of transpiration is 

 seen to have had little effect on its diurnal movement. 



The facts described afford conclusive evidence that the 

 diurnal movement is not mainly dependent on changes 

 in transpiration ; that there is another factor, defined 

 as thermo-geotropism, which co-operates in the diurnal 

 movements of plants. 



Summary 



Continuity is shown to exist between the thermo- 

 geotropic response of rigid trees, young stems, and adult 

 leaves of plants. 



In all these an erectile movement is exhibited from 

 thermal noon to thermal dawn, and a movement of fall 

 from thermal dawn to thermal noon. 



The predominant effect of variation of temperature on 

 the diurnal movement is demonstrated by the absence of 

 any movement when the temperature is constant. 



The effect of the stimulus of gravity in inducing aniso- 

 tropy, which determines the characteristic diurnal move- 

 ment, is proved by the effect of inversion of the plant on 

 the diurnal record. 



The activity of thermo-geotropism as an independent 

 factor in the diurnal movement appears from its persist- 

 ence after the abolition of transpiration. 



The thermo-geotropic movement is in many ways 

 analogous to the thermonastic movement. A wider 

 generalisation is reached by the inclusion under the head of 

 Thermonasty of the response of non-growing organs rendered 

 anisotropic by the stimulus of gravity. 



