178 LIFE AND WORK OF SIR JAGADIS C. BOSE 



photosynthesis being relatively ineffective for tropic reaction, 

 and vice versa. 



Returning to the action of electric waves, since they exert 

 no photosynthetic action they might conceivably induce the 

 complementary tropic effect. These considerations led me to 

 the investigation of the subject fourteen years ago, and my 

 results showed that very short electric waves induce a retarda- 

 tion of rate of growth ; they also produce responsive movements 

 of the leaf of Mimosa when the plant is in a highly sensitive 

 condition. The energy of the short electric waves is very 

 feeble, and undergoes great diminution at a distance ; hence 

 the necessity for employment of a plant in a highly sensitive 

 condition. 



I resumed my investigations on the subject at the beginning 

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

 perceived and responded to long aether-waves reaching them 

 from a distance. The perception of the wireless stimulation was 

 to be tested, not merely by the responsive movement of sensitive 

 plants, but also by diverse modes of response given by all kinds 

 of plants. 



The Wireless System. For sending wireless signals I had to 

 improvise the following arrangement, more powerful means not 

 being available. The secondary terminals of a moderate-sized 

 Ruhmkorffs coil were connected with two cylinders of brass, 

 each 20 cm. in length ; the sparking took place between two 

 small spheres of steel attached to the cylinders. One of the two 

 cylinders was earthed and the other connected with the aerial 

 10 metres in height. The receiving aerial was also 10 metres in 

 height, and its lower terminal led to the laboratory, and connected 

 by means of a thin wire with the experimental plant growing in a 

 pot ; this latter was put in electric connection with the earth. 

 The distance between the transmitting and receiving aerial was 

 about 200 metres, the maximum length permitted by the grounds 

 of the Institute. 



I may state here that with the arrangement described above 

 I obtained very definite mechanical and electric response to 

 wireless impulse. For the former I employed the plant Mimosa ; 

 the latter effect was detected in all plants, sensitive and ordinary. 



Effect of Wireless Stimulation on Growth. For the detection 

 of variation of growth it was necessary to devise the extremely 

 sensitive Balanced Crescograph. In this apparatus a compensat- 

 ing movement is given to the plant -holder by which the plant 



