A GENETICO-PHYSIO LOGIC AL STUDY ON THE FORMATION ETC. 
65 
With respect to the colour of the grain, let two pairs of genes O' o' and 
C c' be responsible. The chromogen C produces the cliromogenic substance 
P in the testa and in pericarp, and c' produces practically none. The gene 
O' converts the cliromogenic substance to a reddish brown pigment especially 
in the testa and o' to a less extent. Thus by G'O' the reddish brown grain 
is formed and by C'o' the yellowish brown grain. The parental reddish brown- 
grain plant may be assumed to be CO' and the “ white ’’-grain plant c'o'. 
The 9:3:4 ratio would arise in F, by selfiug the F l plant Ce' O'o'. Thus 
CO' 9 Reddish brown 
Co' 3 Yellowish brown 
o'O' 3 “ White” 
c'o' 1 
With respect to the colour of the paleas, the segregation in F 2 was similar 
to that of the cross “ Hanbun-nento ” x “ Genroku-mochi ”, so we may assume 
that the analogous genes are concerned in the cross “ Otsubu ” x “ Haguro ” 
in which the grain colours are studied. But one of the genes for the grain 
colours probably O' is completely linked with the gene for the purple colour 
of the palea. Suppose O' is linked with P ' but C is independent of the 
latter, we expect the following segregation in F,. 
BP O'C 27 Awn purple, palea self purple, grain reddish brown. 
BP' O'c' 
9 
99 
99 
“ white ” 
hP'O'C 
9 
99 
localized purple 
reddish brown. 
bP'O’c' 
3 
99 
99 
“ white ” 
Bp'o'C 
9 
brown 
brown 
yellow, brown. 
Bp'o'c' 
3 
99 
99 
“ white ” 
bp’o'C 
3 
99 
yellow 
yellow, brown. 
bp'o'c' 
1 
99 
99 
“ white ” 
If reddish browns, yellowish browns and “ whites ” are added together irre¬ 
spective of the colour of the paleas, we obtain 36 :12:16 or 9:3:4 ratio. 
The ratio of coloured to non coloured grains in each colour types of the paleas 
is 3 : 1 showing that the gene C is independent of P' and O'. 
As we have already seen, green and yellow seed coat of the soy beans 
are dominant over black, brown and buff. The green and yellow contain 
