534 



PLANT RESPONSE 



Table showing Responsive Effects Common to Pulvini, 

 pulvinoids, and growing organs 



Stimulation diffuse 



i. Direct effect. 



Negative turgidity- 

 variation. 



Galvanometric nega- 

 tivity. 



Depression of motile 

 leaf. 



Retardation of 

 growth. 



Stimulation unilateral 



Effect on proximal side 



Effect on distal side 



3. Direct effect. 



Negative turgidity- 

 variation. 



Galvanometric nega- 

 tivity. 



Contraction and 

 concavitv. ' 



Corresponding 

 effect. 



Positive turgidity- 

 variation. 



Galvanometric posi- 

 tivity. 



Expansion and con- 

 vexity. 



Remarks. — It will be remembered that the indirect effect is a secondary con- 

 sequence of the direct contractile effect of stimulus on the excited point. Thus 

 the motive power is the active contraction of that point. The indirect effect, 

 described as No. 7, is exemplified by the moderate unilateral stimulation of the 

 tip of shoot or root. When this stimulus is stronger, or sufficiently long 

 continued, we have a transmission of the direct effect of stimulus, and case No. 7 

 is displaced by case No. 5. 



1 The induction of concavity, of either upper or lower side of the pulvinus, 

 by local stimulation will be found demonstrated in a subsequent chapter. 



Confining our attention to the effects induced at the 

 growing region, we arrive at the following laws of growth- 

 curvature. 



