288 THE CONTINUITY OF THE RACE 



and recombination and independent assortment — but that the independ- 

 ent assortment of three pairs of genes results in the production of eight 

 kinds of gametes and so requires a "checkerboard" with 64 squares. 

 (The "checkerboard" is omitted in the diagram but may easily be con- 

 structed in the same manner as that given for the dihybrid.) 



Diagrammatic Description of Trihybrid Cross 



Pi phenotypes Yellow-round-colored X green-wrinkled-colorless 



Pi genotypes GG WW CC gg ww cc 



Pi gametes GWC gwc 



Pi genotype Gg Ww Cc 



Pi phenotype Yellow-round-colored 



Pi male gametes GWC GWc GwC gWC Gwc gWc gwC gwc 



Pi female gametes GWC GWc GwC gWC Gwc gWc gwC gwc 



The F 2 generation will consist then of : 



27 Distinct Genotypes 8 Distinct Phenotypes 



1 GG WW CC 27 yellow-round-colored 



2 GG WW Cc 

 2 GG Ww CC 

 2 Gg WW CC 

 4 GG Ww Cc 

 4 Gg WW Cc 

 4 Gg Ww CC 

 8 Gg Ww Cc 



1 GG WW cc 9 yellow-round-colorless 



2 GG Ww cc 

 2 Gg WW cc 

 4 Gg Ww cc 



1 GG ww CC 9 yellow-wrinkled-colored 



2 GG ww Cc 

 2 Gg ww CC 

 4 Gg ww Cc 



1 gg WW CC 9 green-round-colored 



2 gg WW Cc 

 2 gg Ww CC 

 4 gg Ww Cc 



1 GG ww cc 3 yellow-wrinkled-colorless 



2 Gg ww cc 



1 gg WW cc 3 green-round-colorless 



2 gg Ww cc 



1 gg ww CC 3 green-wrinkled-colored 



2 gg ww Cc 



1 gg ww cc 1 green-wrinkled-colorless 





