A GENETICO-PHYSIOLOGICAL STUDY ON THE FORMATION ETC. 
69 
phenotype 
F> genotype 
no. of families 
observed 
expected 
difference 
Sr. 
GGrrii 
1 
0.594 
Ggrrii 
1 
1.187 
ggrrii 
— 
0.594 
2 
2.375 
-0.375 
In the 
case of the cross 
“ Waremame 
” X “ Achumuri ” in which buff 
and black are crossed, two pairs of genes are concerned in the formation of 
four types of seed coat, i.e., self black, imperfect black, brown and buff. If 
we let a pair of genes G and c stand for the chromogens, imperfect black 
was found to carry no C, in spite of the fact that the ground-colour appeared 
to be brown, as already mentioned, hence we may assume that the full 
development of the deep purple anthocyanln pigment is only possible by the 
presence of G and R. The gene for the formation of the chromogenic 
substance may therefore have a simultaneous action on the formation of brown 
and self black from the same chromogenic substance. Here the gene G is 
not concerned. The parental plants may have the following genotypic com¬ 
position with respect to the colour of the seed coat : 
Self black GGOORRiigg 
Buff ccOOrriigg 
The F x plant is heterozygous to C and R, and in F, we should expect 
the following families : 
Self black 
CCRR 
1 
Black 
const. 
GGRr 
2 
Black. : brown 
3:1 
CcRR 
2 
Black : imperf. 
black 3 :1 
Self black 
GcRr 
4 
Black : imperf. 
black : brown : buff. 9 : 3 : 3 :1 
Imperfect black 
ccRR 
1 
Imperf. black 
Const. 
ccRr 
2 
Imperf. black : 
buff 3: 1 
Brown 
CCrr 
1 
Brown 
Const. 
a 
Gcrr 
2 
Brown : buff 
3:1 
Buff 
ccrr 
1 
Buff 
Const. 
The actual numbers observed are as follows. 
