Conductivity under Geotropic Stimulation. 



355 



and the growth of the other side produced various twistings. In other cases 

 the whole tip died and numerous lateral roots were produced about 1 cm. 



•■5 To" 

 time in hours 



Fig. 7. 



behind the apex of the main root, which grew very thick for a distance of 

 2-3 cm. from the point. In several cases where the wires were left in roots 

 2-3 cm. long for 48 hours after the experiment, the root grew out of the wax 

 coat and left the wires, being itself apparently unaffected by the injury. 



The changes in the resistance produced by tilting the root were then 

 studied during the period of quiescence. The plant was mounted and 

 readings taken every 15 min. with the root vertical until two consecutive 

 readings were similar, then the root was placed at various angles with the 

 vertical. 



Changes in Resistance and Geotropic Stimulation. 



In all the following experiments roots from 2 to 4 cm. in length were used 

 and the beans were germinated upon a vertical board covered with blotting 

 VOL. xc. — B. 2 F 



