2 8o 



PLANT RESPONSE 



applying stimulus near the proximal contact, the other 

 contact being at a relatively great distance. The periodicity 

 of these multiple electric responses I find to vary in different 



F^ig. 114. Multiple Electrical Responses due to Single Strong Stimulus 



(a) In Mimosa due to thermal, and (b) to chemical stimulation ; (?) in 

 peduncle of Biophytwn, due to thermal stimulus. [N.B.— This series 

 persisted for two hours.] {d), in hypocotyl of Tamarindus indica, due 

 to stimulus of cut. 



cases from about a half to five minutes. These multiple 

 electrical responses, resulting from a single strong stimulus, 



sometimes persist for as long as 

 two hours (fig. 1 14). 



Multiple electrotactile re- 

 sponses. — In the course of my 

 experiments on the electrotactile 

 method of detecting the excitatory 

 wave, I discovered multiple waves, 

 initiated by a single strong stimulus, 

 passing through the tissue. In 

 fig- ll S I S lve a record of such 

 multiple responses in the stem of 

 Mimosa, in which it will be seen 

 that there are four such responses, 

 with an average period of one 

 minute each. 



Now, as these pulsations are 

 signs of the presence of excitation, 

 it follows from the occurrence of such multiple responses 

 that a strong stimulus may give rise to a multiple series 



Fig. 115. Multiple Electro- 

 tactile Response in Stem of 

 Mimosa, due to Single Strong 

 Thermal Stimulus 



(Original record reduced to \.) 



