GENETICO-PHYSIOLOGICAL STUDY ON THE FOBMATION ETC. 
59 
biochemical or physiological processes in the somatic cells that are set free 
by the corresponding genetical make-up. 
In the case of the colour characters in the awn of Oryza sativa, we are 
apparently dealing with instances similar to those that were observed by Miss 
Whet,pat,e in Antirrhinum and Bateson in Lathyrus. Suppose a pair of genes 
C and c are concerned. The gene 0 produces the cliromogenic substance in 
the brown awn to such an amount that it can readly be detected in the 
extract and by c, the production of the same substance is as much as ten to 
twenty times less than that produced by C. Consequently the faint yellow 
awn appears to be devoid of chromogen. 
The oxidation and subsequent changes of the cliromogenic substance 
leading to the formation of brown pigment may be due entirely to post mortem 
changes and may have no relation to the action of a gene whatsoever. If any 
gene is concerned, we may suppose the following possibilities. 
The gene C has the simultaneous action of converting the cliromogenic 
substance to the brown pigment in which the oxidation plays an important 
role. 
Or we may suppose that another gene O, a chromoplielein, which con¬ 
verts the cliromogenic substance to the brown pigment, and the genes G and 
0 are so linked each other that they may be considered as a single gene 
complex. In the awn of Oryza, and in the seed coat of Glycine as we shall 
see later, the chromogenic substance and certain brown pigments which are 
the oxidation product of the former, appear to be due to the action of a single 
gene. Wherever the cliromogenic substance is produced, it is invariably con¬ 
verted to the pigment of plilobaphene nature, unless the inhibitory gene enters 
into the system. In this connection, it is of interest to refer the findings of 
Wolff, Wolff and Rouchermann 1 and Mrs. Wheldale Onslow (1919), 2 
who have shown in a number of cases that the reaction of direct oxidase is 
invariably associated with the presence of the chromogenic substance. 
If the latter assumption is adopted, the genes concerning the formation 
of brown awn may be designated by CO and the faint yellow awn by cd. 
1. WoLIiF, J., Loc. cit. 
Wolff, J, and Rouchermann, N. Loc. cit. 
2. Wheldale Onslow, M., Oxidizing Enzymes. I. The nature of the “ peroxidase ” naturally 
associated witli certain direct oxidizing systems in plants. Bioch. Jour. 13:1, 1919. 
