184 CHAP. XVII. WIRELESS STIMULATION 



It is the less refrangible rays which are most active in 

 the building-up process of photosynthesis. The dynamic 

 and potential manifestations are thus complementary to 

 each other, the rays which induce photosynthesis being 

 relatively ineffective for tropic reaction and vice versa. 



The less refrangible yellow-red rays have been shown 

 to be phototropically ineffective. Proceeding further into 

 the infra-red region of the thermal rays, it has been shown 

 that they become suddenly effective in causing retardation 

 of growth and in inducing tropic curvature. A curve drawn 

 with the wave-length of light as abscissa, and the effective- 

 ness of the ray as ordinate, shows a fall towards zero in 

 proceeding from the violet to the red ; the curve, however, 

 shoots up in the region of the infra-red. Does the effective- 

 ness of the rays for inducing tropic reaction abruptly end 

 with the thermal rays, or does it persist, though in a lesser 

 degree, in the region of the electric radiation, the wave- 

 length of which is enormously greater ? 



It should be borne in mind that the energy of the electric 

 waves which reach the plant from, a distance is relatively 

 feeble, and hence its effect is likely to be slight and detect- 

 able only by an extremely delicate method of record, and by 

 the employment of highly sensitive specimens. 



Before proceeding further with the subject of the possible 

 effect of wireless waves on the plant, I thought it desirable 

 to find out whether or not a rapidly alternating electric 

 field of force has any effect on the plant. 



Response of Plant to High-Frequency Alternating 



Field of Electric Force 



The investigation was undertaken to find whether the 

 plant, placed within the influence of the field generated 

 by high-frequency and high-tension alternating current, 

 exhibited any responsive reaction. The investigations were 

 carried out with Mimosa as well as with growing plants. 



Experiment iii. Effect of alternating field on Mimosa. 

 For the high-frequency alternating current I employed a 



