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DISCUSSION 



Dr. Burstrom: I would like to ask Dr. Lockhart about his results 

 on the influence of gibberellic acid on cell walls. This is a most in- 

 teresting point, of course, and most important, because if you have 

 a change of growth you should have some direct or indirect effect 

 upon the cell wall. 1 would like to ask if you know any more about 

 what is happening here. You measure plasticity by the bending test, 

 and there are two points which surprise me. Firstly, that this plastic 

 bending is going on at a very slow rate and apparently does not come 

 to an end. That would not be expected from a real plastic bending; 

 it ought to be a fairly rapid change. Secondly, you determine, if I 

 am right, the plastic bending after subtracting the reversible elastic 

 bending which obviously is the same at the beginning and at the 

 end of the tests. You have no change in the elastic tension. This is 

 surprising. If you have a plastic change of this kind, you should have 

 a change in the elastic bending because that's also a function of the 



