Conductivity under Geotropic Stimulation. 361 



It will be seen from the graphs (fig. 14) that the turning of the root 

 horizontal results in a considerable increase of permeability in both cases, the 



2000 



1-5 ^0 

 time in hours 

 Fig. 14. 



increase being much less when the root was turned so that the side which 

 was being investigated was uppermost. Different beans were used, howevqf , 

 one for Experiment 8 and another for Experiment 9. The root was left in 

 the horizontal position for the remainder of the experiment and the dilution 

 due to diffusion is represented by the downward curves, these giving an 

 increment of resistance from that of the root when it was first turned 

 horizontal. The decrement of resistance due to loss of vitality starts 

 15-30 min. earlier thair was usual in the other experiments, where no time 

 was given for diffusion to take place as the plant was returned to the vertical 

 immediately after each reading. 



Conclusions. 



From the time of M. C. Bose(2) to the time of J. C. Bose(l) and Fitting (3) 

 very little advance had been made in the explanation of geotropism. 

 J. C. Bose added to the experimental proof that geotropism is due to proto- 

 plasmic action, and interpreted his results as proving a differential change in 

 the turgor on the concave and convex sides of the curve in stems and roots. 



