154< 



THE THEORY OF THE GENE 



numbers are involved, brings out some interesting rela- 

 tions. A few examples will serve as illustrations. 



I^liara examined the hybrid produced by crosses be- 

 tween an Emmer with 28 chromosomes (n=14) and a 

 Vulgare type with 42 chromosomes (n=21). The hybrid 



Fig. 90. 



Eeduction division of hybrid wheats. (After Kihara.) 



has 35 chromosomes. It is therefore a pentaploid hybrid. 

 In the maturation stages (Fig. 90a-d) there are 14 

 gemini and 7 single chromosomes. The former divide, 14 

 going to each pole; the latter, the single chromosomes, 

 are irregularly scattered on the spindle, where they lag 

 for some time after the "reduced" chromosomes have 

 reached the poles (Fig. 90d). Later these single chromo- 



