MULTIPLE EXCITATION BY CURRENT 249 



sets of responses to individual stimuli, applied at intervals 

 of 3 minutes. After this the petiole was subjected to the 

 action of a continuous current, represented below the 

 record as a continuous up-line. It will be seen that under 

 the continuous current, rhythmic excitations were initiated 

 at the kathode, which, reaching the responding leaflet, 

 caused multiple responses. 



There were five such rhythmic responses in the course 

 of 10 minutes, the period of each being 2 minutes. The 



Fig. 124. — Multiple excitation in Biophytum under constant current. 

 First four records are responses to individual stimuli of electrical 

 current of short duration, applied at intervals of 3 minutes. The 

 last five are multiple responses due to continuous action of current. 



production of such multiple excitations in a plant under 

 constant current cannot be explained by the theory of 

 hydro-mechanical blow. On the other hand, their simi- 

 larity to corresponding phenomena in animal tissues is 

 sufficiently obvious. 



Relative Sensitiveness of Plant and Animal to 

 Electrical Current 



There is a general assumption that the sensitiveness of 

 plant tissue is very much lower than the animal tissue. 

 The question then arises : How sensitive is the plant as 

 compared with the animal in the matter of excitation by 

 a constant current ? 



There can probably be no specimen more susceptible 



