4GG LIFE MOVEMENTS IN PLANTS 



contrast to the positive curvature brought about by direct 

 stimulation ; the response of the root is therefore in no 

 way different from that of vegetable tissues in general. 



It will also be seen that an identical stimulus induces 

 two opposite effects, according as the stimulus is applied 

 at the tip or at the growing region itself. In the former 

 case, the stimulus is indirect, and in the latter case it is 

 direct. The results are in strict conformity with the laws 

 of effects of direct and indirect stimiilations that have 

 been established regarding plant response in general (p. 281). 



SUMMARY. 



In the root, the responsive region is in the zone of 

 growth. The tip of the root is separated from the region 

 of response by a semi-conducting or non-conducting tissue. 



Direct unilateral stimulus (applied at the region of 

 growth) 'induces a positive curvature by the contraction of 

 the proximal and expansion of the distal side. 



The electrical response to direct unilateral stimulus is 

 galvanometric negativity of the proximal, and galvanometric 

 positivity of the distal side. 



Indirect unilateral stimulus induces expansion of the 

 proximal side resulting in negative curvature and move- 

 ment away from stimulus. 



The corresponding electric response induced is galvano- 

 metric positivity of the proximal side. 



The responses of the root, to both direct and indirect 

 stimulations, are precisely similar to those in the shoot. The 

 assumption of specific irritability of the root as differing 

 from that of the shoot, is without any justification. 



