A GENETICO-PHYSIOLOGICAL STUDY ON THE FORMATION ETC. 
63 
brown. Tlie cliromogenic substance of the brown pigment in the paleas was 
tested at the time previous to pigmentation but failed. Therefore it is evident 
that the cliromogenic substance of the brown pigment in the palea is diff erent 
from that of the awn which gives rise to the red anthocyanin by the action 
of the B gene. But B has a specific relation to the formation of purple 
pigment in the epidermis, inasmuch as the full colour in the purple palea is 
always associated w T ith the brown ground-colour, and the localized purple 
excludes the latter. It appears therefore that either B has a simultaneous 
action on extending the purple pigment to the entire surface of the palea or 
that the phenomenon is due to another gene which is completely linked with 
B. 
The formation of-any purple pigment in the palea appears to be due to 
another group of genes which are similar in kind to that which afîëcted the 
awn, inasmuch as the purple awn is completely linked with any purple present 
in the palea but no red ever occurs in the latter. Let P' be the gene for the 
presence of purple pigment in the palea, and p' for the absence of the same. 
Further admit that P' and P are linked. Thus 
“ Hanbun-nento ” ppp'p'BB Awn red, paleas brown. 
“ Genroku-mochi ’ ’ PPPP'bb Awn purple, paleas purple localized. 
F l “ Hanb.” x “ Genrok.” PPP'p'Bb Awn purple, paleas purple. 
The F l plant is heterozygous to P’ and B, since P' and P are linked. In 
F, we expect the following genotypes to occur ; 
Genotype 
Phenotype 
Awn Paleas 
Designation 
PP'B 
Purple 
Self purple with brown 
PP 
PP'b 
55 
Localized purple without 
brown. 
P 
pp'B 
Red 
Brown 
B 
pp'b 
55 
Yellow 
Y 
We should expect therefore the following segregation in F> t with respect to the 
colour of paleas. 
Genotype of F., plant Segregation in F 3 Ratio. 
P'P'BB 1 PP Const. 
