POLYPLOID SPECIES 

 Table 31 



215 



Pairing in an Intermediate Octoploid Plant, Bromus erectus var. 

 eu-erecius (2n = 56 = 8x, Kattermann, 1931) 



Type of pairing . 

 Number of cells . 



Total. 

 1. 151 



The third class consists of species in which there is no clear 

 differentiation of the corresponding chromosome sets. They may 



^Y to. 



Fig. 74. — First metaphase in Tulipa Clusiana (5r = 60) showing 8 

 univalents (hatched), 15 bivalents, 3 trivalents, 2 quadrivalents 

 and one quinquevalent. X 4000 (from Newton and D., 

 1929). 



even, in some forms, be considered identical. In others they may 

 be equally dissimilar. They occur as triploids (the result of doubling 

 in one parental gamete) tetraploids (the result of doubling in both 

 parental gametes or somatically and pentaploids (the result of 

 doubling on two occasions). The tetraploids are of somewhat 

 reduced fertility, while the triploids and pentaploids are almost 



