MULTIPLE AND AUTOMATIC RESPONSE 283 



in every instance the whole energy imparted by stimulus 

 gives rise to useful work. Some of it may be wasted as 

 heat. But, on the other hand, it is conceivable that the 

 excess of this energy may be stored up, for the time being, 

 to find subsequent expression. To take a physical illustra- 

 tion, the energy stored up in a compressed spring may, 

 on release, give rise to long-continued and rhythmic oscilla- 

 tions. The question arises, then, whether in the leaflet of 

 Biophytum, impressed by an excess of stimulation, there may 

 be any analogous storage of energy. Supposing this to take 

 place, the superfluous energy might be utilised to do some 

 internal work not discernible by the observer ; or it might, in 

 favourable circumstances and in the presence of suitable 

 motile indicators, find expression in rhythmic movements. 



I have referred elsewhere to another mode of recording 

 excitatory response in plants — namely, the electrical. 

 Using this, I have frequently observed that although under 

 a moderate stimulus a single stimulus gives rise to a single 

 electric response, yet under a strong stimulus there would 

 arise a series of responses. Thus, while a feeble stimulus 

 induced a single response, a strong stimulus gave rise to 

 multiple responses. 



Having this in mind and the peculiar characteristics of 

 Biophytum response, I expected to demonstrate the occur- 

 rence of multiple responses by means of mechanical move- 

 ments. It had already been noticed that Biophytum when 

 strongly excited closed its leaflets, not by one but by two 

 successive twitches. It appeared to me that this curious 

 phenomenon was parallel to the multiple response of rhythmic 

 animal tissues ; and I expected, if this were so, that instead 

 of two it would be possible to obtain from it a long series of 

 rhythmic responses comparable with the multiple rhythmic 

 responses in animal tissues. In order to obtain this in the 

 case of Biophytum it was necessary to prevent the complete 

 closure of the leaflet, in consequence of which further 

 exhibition of mechanical response is rendered impossible. 

 This was secured by applying a light counterpoise in the 



