PARTHENOGENESIS 



181 



bring this case into line with the rest of our informa- 

 tion bearing on the relation of the chromosomes to sex. 

 One important point still remains to be explained.* 

 What causes some of the migrants to produce large 



I'HYLLOXERA CAnYMCAULTfi 



T'o^ev^ T»^cae^ A ^ r^ 



O^nt^v of ffZn^efi -^en. 



I 



C:::d 



•^n? 



o 





o 



o 





o 



o 



o 



\ 



•^^ocfM/ fs-ma/t. ^p ^' 



.^ 







X is X 



4. 



o 







7vCa/f S^iiyndlc 



<3 



^f 



\ 



^- 



TKaZe' 





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Fig. 93. — Chromosomal cycle of P. carycecauUs. 



