60 
I. NAGAI : 
Further we admit that the gene R is present in the faint yellow awn plant, 
and by the completion of the system provided by the genes GR {COR), the 
cliromogenic substance is converted to red anthocyanin, but by cR (coR ) and 
cor (cor) the system is incomplete. The parental faint yellow plant may there¬ 
fore be designated by cR ( coR ) and the brown plant by Gr ( GOr). The red 
awn F 1 plant is Gc Rr ( GOcoRr) and by setting, the following zygotic series 
would arise in F, by the ratio 9 : 3 : 3 : 1, viz., GR (COR), Gr (GOr), cR 
(coR), and cor (cor), and in which the last four would be faint yellows giving 
rise io 9 reds, 3 browns and 4 faint yellows. The assumption covers the 
numerical ratio observed in the F, and F, generations. 
Let us suppose in another way that the brown awn may have the genetic 
composition GOr and the faint yellow cOR, in which 0 is the gene common 
to both of the parental plants. It is necessary to suppose that no red - an¬ 
thocyanin should be formed by cOR in which the chromogenic substance 
produced is only in such a small amount that no anthocyanin is formed from 
it even in the presence of OR. If however, the reduction processes set work¬ 
ing by the gene complex here concerned are just as powerful as we provide 
in vitro by means of hydrochloric acid and magnesium powder, even a trace 
of the chromogenic substance should be converted to the coloured anthocyanin, 
for, we can readily detect even a trace of the chromogenic substance (1 : 20,000) 
by a distinct pink colour by reduction. 
In the case of the cross “ Hanbun-nento ” x “ Genroku-moclii ”, in which 
the purple and red awn are concerned, the basal system of anthocyanin 
formation CR is complete in both of the parental plants. If we let the gene 
R' convert the red anthocyanin to purple, the purple awn may be designated 
by CRR' and the red by GRr'. The designation CRR ! may be substituted 
by a single letter, say P, and GRr' by p. Since we observe the stages of the 
change, chromogen —> red pigment —> purple pigment in the plant, GRR' 
seems to represent the actual phenomena occurring in the sporophyte. 
In a number of cases reported, the purple colour is dominant over the 
red. 1 In Antirrhinum Miss. Whedale (1914)’found that orange anthocyanin 
1. See summary in Bateson, W., Mendel’s Principles of Heredity. Third edition. 1913. 
Wheldale, M., Anthocyan Pigments of Plants. 1916. 
2. Wheldale, 31., Our Present Knowledge of the Chemistry of the Mendelian Factors for 
Flower Colour. Jour. Genet. 4: 8, 1914. 
