longitudinal response of radial organs 8 1 



Summary 



In a radial organ, unilateral stimulation causes contrac- 

 tion, and consequent concavity of the acted side. 



Under diffuse stimulation there is no resultant lateral 

 response, owing to the balanced and mutually antagonistic 

 character of the contractions. 



A radial organ under diffuse stimulation exhibits longi- 

 tudinal contraction. 



Longitudinal contractions are observed in the radial 

 organs of all plants. 



Such responsive contractions as seen in some ' ordinary ' 

 plants are strictly comparable in extent to those which are 

 known to occur in the sensitive filaments of Cynercce. 



These excitatory responses are modified by all those 

 agencies which affect the physiological condition of the plant. 



