A. R. SCHRANK 



135 



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Figure 6. Successive stages of Avena coleoptile curvature after transverse 

 application of 10 microamperes for 10 minutes. Current applied 10 millimeters 

 below the apex. 



These curvature data permit several interesting observations. First, 

 it would appear that the applied current is inducing the curvature by 

 affecting the auxin-controlled mechanisms. This tentative conclusion 

 is drawn from the fact that the zone of curvature moves toward the base, 

 which is clearly shown in Figure 6. More specifically, this could be 

 interpreted to mean that the current has actually affected the lateral 

 transport of the auxin. Secondly, from Thimann's work on the distri- 

 bution of auxin along the longitudinal axis of the coleoptile (34) and the 



TABLE 1 

 Degrees of curvature of the Avena coleoptile 



