174 A. POLJAKOFF-MAYBER 



DISCUSSION 



Keynan : You mentioned, that by using a different part of the 

 Hght spectrum you can 'unswitch' tiie stimulation of germination 

 by red light. However, after about two hours this 'unswitching' 

 is no longer possible and germination proceeds. Is there any 

 visible or measurable change during these two hours? 



Poljakoff-Mayber : Our methods are not sufficiently refined 

 to allow an answer to your question. 



GoLDWASSER : What is the range of concentrations at which 

 these inhibitors and stimulators act, and what quantities do you 

 succeed in isolating? 



Poljakoff-Mayber: While we can extract quantities sufficient 

 to obtain the necessary effects, these quantities are not sufficient 

 for measuring purposes. 



Goldwasser: Well, in that case you ought to be able to 

 measure the changes occurring in the seeds indicated by Dr. 

 Keynan. 



Poljakoff-Mayber: We hope to succeed in doing so, once 

 we have refined our methods sufficiently. 



