THE MODIFICATIONS OF THE CHROMOSOME CYCLE 



65 



ploid {'jx heptaploid is missing), 8jc octoploid, 9;c nonaploid, lOx 

 decaploid, etc. If any of these types regularly forms gametes with half 

 the somatic number of chromosomes, it can also be written as 2«, as is 



.•>? 







# 



»» 



Fig. 24. Autopoiyploid Tomatoes. — Mitotic chromosomes below and leaves 

 above, A diploid 2n = 24, 6 triploid In == 36, C tetraploid 2n = 48. 



(From Hurst, after J^rgensen.) 



usual for the diploid; but we shall see that gametes are not always 

 regularly formed, and a notation which gives the multiple of the basic 

 number, such as 6a:, conveys more important information than one 

 which merely gives the somatic number. 



V 



Oi 



Fjg. 25. Polyploid Series in Crepis. — Mitotic metaphases in haploid, diploid, 

 trisomic diploid, triploid and pentaploid Crep'is capillaris (n = 3). 



(From Darlington, after Hollingshead and Navashin.) 



