104 



CHAP. XI. PHOTOTROPIC EFFECT OF LIGHT 



organ. Recovery took place in the course of 8 minutes 

 (fig. 51). Similar effects were observed with the leaflets of 



Fig. 51. Positive tropic effect of light on pulvinated organ. 



Responses to successive stimulations by light. Up-curve repre- 

 sents up-movement, and down- curve represents recovery. 

 (Phaseolus.) 



Erythrina indica and of Clitoria Ternatea. The movement 

 under light from above has for simplicity been described 



Fig. 52. 



Positive response of leaflets of Erythrina indica. 

 (Para-heliotropic response.) 



as upward. But the actual direction in which the leaflets 

 point their apices is towards the source of light. Both 

 these plants are so remarkably sensitive that the leaflets 



