408 W. P. Jacobs 



with the resuks meaningfully related to the normal physiology. To 

 better understand the role of the plateau capacity of auxin trans- 

 port, we need to know how stable is this plateau level. From the 

 current view of auxin transport it would be reasonable to expect 

 that continued exposure to higher than normal auxin levels would 

 cause gradual regulation in the plateau capacity. Knocking out 

 auxin movement by the addition of chemicals (2, 3, 17, 18) may lead 

 to an understanding of the biochemical basis of auxin transport. It 

 would be particularly intriguing if a chemical could be found which 

 would actually knock out the polarity — i.e., allow equally fast move- 

 ment of auxin in both directions in a normally strictly polar organ 

 like the coleoptile. 



ACKNOWLEDGMENT 



Grateful acknowledgment is made to the National Science Founda- 

 tion and to the American Cancer Society for grants in support of 

 the research reported here. 



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