POLYPLOID SERIES 



153 



chromosome splits, and 14 daughter chromosomes move 

 to each pole. In the Vulgare type the 21 gemini divide 

 at the first maturation division. Twenty-one go to each 

 pole. At the second division the daughter halves split and 

 21 move to each pole. 



Hqploid 



Em Korn 



mmer 



Vul 



s 



are 



14 



21 





"&* 



,•* 







»%'/.. 

 W 





<&< 



* 



* 



— ■ 



Fig. 89. 



The first, or reduction, division of diploid, tetraploid, and hexa- 



ploid wheats. (After Sax.) 



This series of types may be interpreted as diploid, 

 tetraploid, and hexaploid. Each is balanced and each is 

 stable. 



Crosses have been made between several of these types 

 with different chromosome numbers. Some of the com- 

 binations produce slightly fertile hybrids, others com- 

 pletely sterile ones. The behavior of the chromosomes in 

 several of the combinations, where different parental 



