252 RESEARCHES ON IRRITABILITY OF PLANTS 



of Biophytum would doubtless prove to be about ten times 

 as sensitive. 



The improbability of the theory of hydro-mechanical 

 disturbance becomes evident when we realise that an 

 excitatory impulse is initiated and transmitted in the plant 

 under a stimulus that cannot even be perceived by the 

 extremely sensitive human tongue. 



Summary 



Nerve-excitation by constant current is enhanced by 

 cooling and depressed by warming. This is one of the 

 characteristics of polar excitation by constant current. 



Similarly the excitability of conducting petiole of Mimosa 

 to polar excitation is enhanced by cold and depressed by 

 warmth. Minimal excitation becomes maximal under 

 cold, and ineffective under warmth. 



The passage of a constant current through the petiole of 

 Biophytum gives rise to series of multiple excitations. 



The sensitiveness of Biophytum to an electrical current 

 is remarkably high. Compared with the very sensitive 

 human tongue, the sensitiveness of Biophytum is about ten 

 times as great. 



