UNIVERSALITY OF SENSITIVENESS IN PLANTS 33 



of application. It will also be remembered that the state of 

 excitation is attended by an expulsion of water, or negative 

 turgidity-variation. After causing galvanometric negativity 

 of the proximal contact, the excitation may reach the distal, 

 and bring about reversal of response, thus constituting a 



Fig. 24. Electric Response Recorder 



diphasic variation. If, however, the distal point be very far, 

 the excitation may by transmission through the long tract 

 become so enfeebled as to produce practically no effect at 



Fig. 25. Method of Transmitted Stimulation 



Stimulus applied to the right at x . Excitation reaches right contact first, 

 causing galvanometric negativity of the point. 



that point, in which case we obtain only the monophasic 

 response of the proximal point. 



Simultaneous mechanical and electrical events, 

 ensuing on excitation.— We may prove that these electrical 

 responses are undoubtedly signs of excitation, by choosing 



D 



