282 



M. K. Bach and J. Fellig 



> 

 > 



O 



< 



UJ 



> 



< 

 UJ 



6.5 



HOURS 



Fig. 4. The eflctt of polarity on the locaHzation of radioaclivily in bean stems fol- 

 lowing exposure to l-C"-2,4-D. The relative radioactivities 5 mm. from the point 

 of application are compared. Open bars, planted basal end down. Closed bars, 

 planted apical end down. 



to 3 mm. from the point of application, even in the presence of the 

 unlabeled 2,4-D- This suggests that the dilution of label in this area 

 was very gradual, perhaps because the radioactive material was bound 

 in some way to the cellular material. Figure 4 shows the effect of 

 polarity on the transport of radioactive material through the stem 

 sections by comparing the relative radioactivities 5 mm. from the 

 point of application of l-Ci'*-2,4-D. The results were factored as in 

 Figiue 2. In contrast to the absence of polarity effects on the total up- 

 take of 2,4-D, the translocation of radioactivity in the sections was 

 clearly faster in the apex to base direction. 



