CHAPTER XIII 



THE RESPONSE OF PLANTS TO WIRELESS STIMULATION 



THE distinction that used to be drawn between plants and 

 animals, that the former did not possess any conducting 

 tissue analogous to the nerve of the animal, has been by 

 Bose's work proved to be groundless. It was nevertheless 

 urged that the sensibility of plants was comparatively of a 

 very low order. Bose undertook to show that this was by 

 no means the case. The most sensitive organ for the 

 perception of electric current is the tip of the human tongue, 

 and a European can detect by his tongue a current 

 as feeble as 6 micro-amperes, a micro-ampere being the 

 millionth part of a unit of electric current. Bose's pupils, 

 however, possessed a higher sensibility, inasmuch as some 

 of them could detect a current which was only 4-5 micro- 

 amperes. This highly sensitive tongue was then matched 

 against the sensitive leaflet of the plant Biophytum. A 

 very feeble current which could be gradually increased was 

 passed through the tongue and the leaflet, and when it 

 reached the intensity of 1-5 micro-ampere the leaflet 

 wagged in response, while the overrated tongue had 

 nothing to tell as regards its perception of the current, 

 which had to be increased threefold before it was per- 

 ceived. Thus by this test the plant was three times more 

 sensitive than the Hindu and four times more so than 

 the European ! 



A record has already been given in a previous chapter 

 (Fig. 15), which shows that the plant becomes depressed 



172 



