300 LIFE MOVEMENTS IN PLANTS 



As the after-effect of direct stimulus is an acceleration of 

 fifrowth above the normal, the stimulated side undergoes an 

 expansion by which the recovery is hastened. 



Unilateral application of direct stimulus induces a posi- 

 tive curvature, but the same stimulus applied at a 

 distance from the responding region induces a negative 

 curvature. 



The tendril of Pdssijlora is excitable both on the upper 

 and under sides ; the excitability of the under side is 

 about seven times greater than that of the upper side. 



Stimulation of one side of the tendril induces an ex- 

 pansion of the opposite side, even in cases where the con- 

 tractility of the stimulated side is feeble. 



The response to stimulation of the more excitable side 

 of the tendril is thus inhibited by the stimulation of the 

 opposite side. This is because of the neutralisation of the 

 effect of direct by that of indirect stimulation. 



