276 



LIFE MOVEMENTS IN PLANTS 



thus succeeded Ly the concave curvature (Fig. 99). Direct 

 application of stimulus at the growing region gave rise 

 to a positive curvature. 



Fig. 99.— Tropic curvature of Crinum to unilateral indirect stimulation of 

 increasing intensities : S, S' of moderate intensity induced negative tropic effect 

 (movement away from the stimulated side) ; stronger stimulus S" gave rise to 

 negative followed by positive. Successive dots at intervals of 5 seconds Magnifi- 

 cation 100 times. 



The effect of feeble stimulus transmitted longitudinally 

 is thus found always to induce convexity, a negative 

 curvature and movement away from stimulus. I 

 have obtained similar responsive movement of negative 

 sign with various plant organs, and under various formg 

 of stimuli. Thus in the stem of Dregea volubilis the 

 longitudinally transmitted effect of light of moderate 



