RESPONSE TO WIRELESS STIMULATION 417 



a aingle octave, the wave lengths of which lie between 

 70 X 10-8 cfji a,^(i -^5 X 10-6 q^ i^ [^ difficalt to 

 imagine that plants could perceive radiations so widely 

 separated from each other as the visible light and the in- 

 visible electric radiation. 



But the subject assumes a different aspect, when we 

 take into consideration the total effect of radiation on the 

 plant. Light induces two different effects which may 

 broadly be distinguished as external and internal. The 

 former gives rise to movement ; the latter finds no outward 

 manifestation, but consists of an ' up ' or assimilatory chemi- 

 cal change, with concomitant increase of potential energy. 

 Of the two reactions then, one is dynamic attended by dis- 

 siniilatory 'down' change; the other is potential, associated 

 with the opposite ' up ' change. In reality the two effects 

 take place simultaneously ; but one of these becomes pre- 

 dominant under definite conditions. 



The modifying condition is the quality of light ; with 

 reference to this I quote the following from Pfefter : " So 

 far as is at present known, the action of different rays of 

 the spectrum gives similar curves in regard to heliotropic 

 and phototactic movements, to protoplasmic streaming and 

 movements of the chloroplastids as well as the photonastic 

 movements produced by growth or by changes of turgor. 

 On the other hand, it is the less refrangible rays which are 

 most active in photo-synthesis."* The dynamic and poten- 

 tial manifestations are thus seen to be complementary to 

 each other, the rays which induce photo-synthesis being re- 

 latively ineffective for tropic reaction and vice versa. 



Returning to the action of electric waves, since they 

 exert no photo-synthetic action they might conceivably 

 induce the complementary tropic effect. These considera- 

 tions led me to the investigation of the subject fourteen 



* Pfeffer— Vol. II, p. 104. 



