41 8 LTFfi MOVEMENTS IN ?LANfS 



years ago, and my results showed that very short electric 

 waves indace a retardation of rate of growth ; they also 

 produce responsive movements of the leaf of Mimosa, when 

 the plant was in a highly sensitive condition.* The energy 

 of the short electric waves is very feeble, atjd undergoes 

 great diminution at a distance ; hence the necessity of em- 

 ployment of a specimen of plant in a highly sensitive con- 

 dition. 



I resumed my investigations on the subject at the begin- 

 ing of this year. I wished to find out whether plants in 

 general perceived and responded to the long ether waves 

 which reached it from a distance. The perception of the 

 wireless stimulation was to be tested not merely by the 

 responsive movement of sensitive plants, bat by diverse 

 modes of response given by all kinds of plants. 



Stimulus induces, as we have seen, three different types 

 of response in plants. It causes excitation in sensitive 

 plants like Mimosa, in consequence of which the leaf 

 undergoes a fall ; this is the mechanical response to 

 stimulus. Stimulus also induces electric response in plants, 

 both sensitive and ordinary, the excited tissue undergoing 

 an electric change of galvanorajtric negativity. Finally, the 

 effect of stimulus on growing plants is a variation in the 

 rate of growth, an acceleration under feeble, and a retarda- 

 tion under strong stimulus. I undertook to investigate the 

 effect of electric waves on plants by the methods of 

 mechanical and of electrical responses, and also by that of 

 induced variation of growth. 



THE WIRELESS SYSTEM. 



For sending wireless signals, I had to improvise the 

 following arrangement, more powerful means not being 



* "Plant Response" -p. G18 (1905). 



