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I. NAGAI : 
present in relation to the formation of antliocyanin pigments in plants. One 
of them includes those which are known as the chromogen factors, and the 
other includes those which are complementary to the former. A complete 
system provided by the union of these genes produces the plant in which 
the formation of anthocyanin pigment is realized. To designate those genes 
C is often used for the cliromogen, and li for the complementary one. The 
most simple case is the counterpart of two genes G and li. We may denote 
those genes which are related to the formation of the chromogenic substance 
in plants by ‘chromogens ’ ( G) and those which are related to the formation of 
any biochemical agency, by means of which the chromogenic substance is 
converted to a coloured anthocyanin or brown pigment, by ‘ chromopheleins ’ 
(R, 0, etc.). According to the view put forward by Miss Wheldale, the 
chromogen factors in the flower of Antirrhinum are related to the formation 
of certain flavone glucosides (glucoside of apigenin and luteolin) and the 
chromopheleins are related to certain oxidizing agencies probably the 
peroxidases. 
It must clearly be understood that the phenomena of inheritance and 
development are of different kinds, and the data of the latter should not be 
confused in interpreting the genetical data. The factor is such an entity of 
the organism that by its means certain groups of biochemical reactions are set 
jree to build up the character which is the phenotypic expression of the 
gene. The biochemical reactions and their products alone are dealt with as 
physiological and developmental data. Some of them can well be regarded 
as the clue to the difference in the genetical units, but these phenomena 
themselves are nothing to do with those of inheritance. A well marked, 
different biochemical phenomena may not necessarily correspond with the 
difference in their genetical potency. 
It is an impossible task to know r all the biochemical changes which are 
governed by a given gene ; all we can attempt, if at all, is to find certain 
correlations between the known biochemical facts and the genetical data, by 
which the chief function of the gene may be inferred. Such an attempt may 
be useless or may fall short of the aim. But, as the writer believes, genetics 
aims to discover not only the laws of the mechanism of distribution of 
hereditary units, but also the finks between the gene and the actual 
