58 COMPARATIVE ELECTRO-PHYSIOLOGY 



turgidity-variation, with the concomitant effect of expansion, 

 and, in the case of Mimosa, of erection of the leaf. This 

 latter effect of positive turgidity-variation and expansion, 

 I shall therefore distinguish as the INDIRECT EFFECT of 

 stimulus, in contradistinction to the term INDIRECT STIMU- 

 LATION, as it is generally used. The last-named, however, 

 I shall myself always refer to under the title of TRANS- 

 MITTED STIMULATION. If the intervening tissue be of 



FlG. 44. Mechanical Response of Biophytum to Thermal Stimulation 



Stimulus was applied at some distance from the responding leaflet. And 

 the preliminary erectile twitch is due to the prior arrival of the 

 hydrostatic disturbance. Thick dot represents moment of application 

 of stimulus. 



moderate conducting power, we shall, as in the case of the 

 experiments on Mimosa, obtain a preliminary erectile twitch, 

 due to the indirect effect of stimulus, followed by a fall, in 

 consequence of the transmission of the true excitatory effect. 

 In fig. 44 is seen this twofold expression of the indirect 

 and transmitted effects of stimulus, given by the leaflet of 

 Biophytum. 



These two waves, then, of increased hydrostatic tension 



