52 PLANT RESPONSE 



plant may thus be sensitive, and yet fail to exhibit mechani- 

 cal response. Hence the absence of mechanical response is 

 no indication of the plant's insensibility. 



In a radial organ under diffuse stimulation there can be 

 no lateral response, owing to the balanced and mutually 

 antagonistic character of the contractions produced. 



The excitatory differential contraction in Mimosa would 

 be inconspicuous but for the magnification produced by the 

 long petiolar index. 





