220 COMPARATIVE ELECTRO-PHYSIOLOGY 



case of sensitive plants when responsive mechanical move- 

 ments were prevented from taking place by physical 

 restraint (p. 20). Tfee mechanical and electrical responses 



arc thus independent modes of expression of a single funda- 

 mental excitatory process. In order to demonstrate this in 

 the case of the autonomous pulsation of Desmodium^ I first 

 obtained simultaneous mechanical and electrical responses of 



FIG. 145. Photographic Record of Simultaneous Mechanical and 

 Electrical Pulsation in Leaflet of Desmodium^ before and after Physical 

 Restraint of Leaflet. 



The first part of this record shows both mechanical and electrical pulsa- 

 tion. In the second part, leaflet was physically restrained, as seen 

 in the mechanical record, becoming horizontal. Electrical pulsation 

 now seen to persist with even greater vigour than before. 



the leaflet (fig. 145). In the next part of the same record the 

 mechanical movement of the leaflet was restrained, as seen in 

 the upper mechanical record, which here becomes a straight 

 line. But the lower record, which gives the electrical re- 

 sponse, still shows the double electrical pulsation unimpeded. 

 Indeed, so far from the mechanical response having been 

 the cause of the electrical, we find that on its arrest, at 

 least in this particular case, the latter becomes very 



