Daily movement DtJE to TUfiRMO-GEOTtlOPlSM 5')0 



That the phenomenon is not nastic, hut paratonic will 

 be demonstrated : — 



(a) by the reversal of closure into opening movement 

 and vice versa, in consequence of inversion of 

 the plant upside down, and 



(h) by the diurnal variation of torsional movement, the 

 direction of which is dependent on the directive 

 action of the stimulus of gravity. 



I shall now describe the diurnal movement of various 

 geotropically curved plant-organs ; the most striking 

 example of this is furnished by the ' Praying ' Palm of 

 Faridpore, already described. I shall here recapitulate some 

 of the important features connected with the phenomenon. 



DIURNAL MOVEMENT OF PALM TREES. 



Movements similar to that of the Faridpore Palm 

 (p. 12) are found in other Palm trees growing at an 

 inclination from the vertical. I reproduce once more the 

 diurnal curve given by the Sijberia Palm together with the 

 curve of daily thermal variation (Fig. 199). It will be 

 seen that the two curves resemble each other so closely 

 that the curve of movement of the tree is practically a 

 replica of the thermographic record. There can therefore 

 be no doubt of the movement being brought about by 

 variation of temperature ; rise of temperature is attended 

 by the movement of fall of the tree and vice vsrsd. The 

 record was commenced at noon ; the temperature rose till 

 the maximum was reached at about 3 p.m. and the tree 

 also reached its lowest position at 3-45 p.m., the lag 

 being 45 minutes. The temperature fell continuously after 

 the maximum at 3 p.m., to the minimum at 6 a.m. next 

 morning. In response to the falling temperature, the tree 

 exhibited a movement of erection. The temperature rose 



