Ali'TEH-EPFECT OJ' LIGHT 575 



upper half of the pulviiius. This gave rise first to a 

 maximum positive curvature, subsequently diminished by 

 transverse transmission of excitation. Neutralisation took 

 place after ai)plication of light for 17 minutes. On ihe 

 stoppage of light, there was a sudden overshooting below 

 the zero line (Fig. 200), and the rate of the movement on 

 the cessation of light was nearly twice as quick as during 

 the process of neutralisation. 



SUMMARY. 



The after-eftect of light is modified by the duration of 

 exposure to light. 



Under continued action of light, the electric response of 

 galvanometric negativity in plants attains a maximum after 

 which it undergoes decline, and neutralisation. 



The electrical after-effect exhibits characteristic differ- 

 ences depending on the duration of previous exposure to 

 light. 



The pre-maximal after-eft'ect is a temporary continuation 

 of response under light followed by recovery. 



The after-effect at the maximum is a recovery to the 

 normal equilibrium. 



The after-effect at post-maximum is an 'overshooting' 

 below the position of equilibrium. 



The immediate and after-tropic response of light are 

 similar to the corresponding photo-electric effects. 



The pre-maximum after-effect is a continuation of 

 positive tropic movement followed by recovery ; the after- 

 eflFect at maximum is a recovery to the normal equilibrium 

 position of the organ. The post-maximum after-efiect is an 

 overshooting below the position of normal equilibrium. 



