RESPONSE TO WIRELESS STIMULATION 423 



incident wave and the response, was only a tew seconds 

 (Fig. 15Gb). The record given in the figure was obtained 

 with the moderate magnification of 2,000 times only. But 

 with my Magnetic Crescograph, the magnification can 

 easily be raiseil ten million times ; and the response of 

 plant to the space signalling can be exalted in the same 

 proportion. 



Under an intensity of stimulus slightly above the 

 sub-minimal, the responses exhibit retardation of growth 

 followed by quick recovery, as seen in the series of records 

 given in Fig. 156c. 



A remarkable peculiarity in the response was noticed 

 during the course of the experiments. Strong stimulation 

 by ether waves gives rise, as we have seen, to a very 

 marked retardation of the rate of growth. Repeated 

 stimulation induces fatigue, and temporary insensitiveness 

 of the organ. Under moderate fatigue the effect is a 

 prolongation of the latent period. Thus in a particular 

 experiment the plant failed to give any response to a 

 short signal. But after an interval of five minutes a 

 marked response occurred to the wireless stimulus that 

 had been received previously. The plant had perceived the 

 stimulus but on account of fatigue the latent period was 

 prolonged, from the normal 5 seconds to as many minutes. 



SUMMARY. 



Plants not only perceive, but also respond to long ether 

 waves employed in signalling through space. 



Mechanical response to wireless stimulation is exhibited 

 by the leaf of Mimosa pudica. 



32 



