132 



THE THEORY OF THE GENE 



functional, regardless of the distribution of the unpaired 

 chromosomes, or, in other words, all or most of the pos- 

 sible different groups of egg-cells survive and may be 

 fertilized. The outcome is a varied assortment of forms 

 with many different combinations of chromosomes. On 

 the other hand, when the pollen of a triploid Oenothera 



Fig. 80. 



Triploid chromosome-group of the pollen mother cell of the Hya- 

 cinth. (After Belling.) 



is used, the results show that only those carrying 7 or 14 

 chromosomes are functional. The pollen grains with 

 intermediate numbers are, for the most part, not func- 

 tional. 



Triploid hyacinths have been found under cultivation 

 by de Mol. He states that they are replacing the older 

 types as a result of selection for commerce. Some of their 

 derivatives, with chromosome numbers varying around 

 the triploid, constitute a considerable part of modern cul- 



