230 B. Abers: 



(s 



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DISCUSSION 



Dr. Wain: Dr. Wightman showed very striking competitive antag- 

 onism eliects with one stereoisomer against another. The main hy- 

 pothesis underlying this work was that the ring system anchors the 

 auxin down to some surface at what you might call the primary site 

 of action. Therefore, compounds of similar structure \\ith the same 

 ring system might very well anchor down without producing the 

 growth response. Very striking effects on competitive antagonism 

 were shown in this work both in the wheat cylinder elongation test 

 and pea curvature test. 



