No. 632] CHIASM ATYPE AND CROSSING OVER 



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rings. As soon as we look further we encounter what 

 seems at first sight to be a hopeless contradiction be- 

 tween the conclusions of Janssens and those of others. 



Janssens, holding fast to the general interpretation out- 

 lined in his earlier development of the chiasmatypr 

 theory, considers the compound rings to have resulted 



