THE DETERMINATION OF SEX 273 

 APHID-PHYLLOXERAN CHROMOSOME CYCLE 



Soma of stem-mother and 

 migrantfemales (her daughters) 



Parthenogenetic eggs 

 of migran t females 



giving rise ^ v * 

 to JT ^^ 



Anaphase of the single 

 maturation division 



Fio. 84. The chromosome cycle in parthenogenesis of aphids and 

 phylloxerans. 



2n + # chromosomes (five in number) and that such 

 an egg forms a male. On the other hand, in the larger 



