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DISCUSSION 



Lees : If the low temperature requirement for seeds is a kind 

 of area restrictive device, I cannot see its value from the evo- 

 lutionary point of view. Why should the evolution not be such 

 that, while such a device is present in cold climates, the device 

 gradually disappears when the plant moves to a warmer climate. 

 This is what happens in insects. 



Koller: Certain varieties growing in moist regions require 

 much higher rainfall to wash away inhibitors of germination 

 than other varieties of the same plant growing in deserts. This 

 may be a partial answer to your question in a parallel case. 



Mayer : What is the ecological or survival value of the Red- 

 Far Red mechanism in germination and in flowering? 



Koller : The Red-Far Red system is just one part of the 

 intricate 'biological clock' by which the organism recognizes the 

 seasons. 



