POLYPLOID NUMBERS 



6i 



Table 6 

 Types of Chromosome Constitution 



Trisomic Tetraploid 



{4X - I). 



AAAA 

 BBBB 

 CCC 

 DDDD 

 EEEE etc. 



Pentasomic Tetraploid 

 (4X + I). 



AAAAA 

 BBBB 

 CCCC 

 DDDD 

 EEEE etc. 



Datura, Belling and Blakeslee, 1924. 

 Primula kewensis, Newton and Pellew, 1929. 

 Biscutella Icsvigata, Manton, 1932. 

 Cf. Triticum vulgare {6x + 1), Kihara, 192 1 

 Huskins, 1928. 



Doubly Hexasomic Tetraploid 



{4X + 2 + 2). 



AAAA AA 

 BBBB BB 

 CCCC 

 DDDD 

 EEEE etc. 



Secondary polyploids, 

 e.g., Dahlia Merckii. 

 Pomoideae {v. Ch. VI). 



" balanced " variation. Polysomy, on the other hand, does involve 

 such a change ; it is said to be an " unbalanced variation," and 



