68 I. NAGAI : 



present in relation to the formfition of authoejanin pigments in plants. One 

 of Wiem includes those which are known as the chromogen factors, and the 

 other includes those which are complementarv to the former. A complete 

 system provided by the union of these genes produces the plant in which 

 tho formation of anthocvanin pigment is realized. To designate those genes 

 O is often used for the chromogen, and R for the complementary one. The 

 most simple case is the counterpart of two genes C and i?. We may denote 

 those genes which are related to the formation of the clu-omogenic substance 

 in plants by ' chi-omogeus ' ( C) and those which are related to the formation of 

 any biochemical agency, by means of ivhicli the chromogenic substance is 

 conveiied to a coloured anthocyauin or brown pigment, by ' chromopheleins ' 

 (J?, 0, etc.). According to the view put forward by I\liss Wheld.\le, the 

 chromogen factors in the flower of Antivrldnvm are related to the formation 

 of certain flavone glucosides (glucoside of apigenin and luteoUn) and the 

 chromopheleins are relatid to certain oxidizing agencies probably the 

 peroxidases. 



It must clearly be understood that thi 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 gi'oups of biochemical reactions are set 

 jree to build up the character which is the phenotypic expression of the 

 gene. The biochemical reactions and their produces alone ai-e dealt with as 

 physiological and developmental data. Sjme of them can well be regarded 

 as the clue to the difference iu the genetical units, bu!: these phenomena 

 themselves are nothing to do with those of inheritance. A well marked, 

 different biochemical phenomena may not necessarily correspond with the 

 difference iu their genetical potency. 



It is an impossible task to know all the biochemical changes which are 

 governed 1 ly a given gene ; all we can attempt, if at all, is to find certjiiu 

 coiTelations between the known biochemical facts and the genetical data, by 

 which the chief fimctiou of the gene may be inferred. Such an attempt may 

 be useless or may fall sliort of the aim. But, as the «Titer believes, genetics 

 aims to discover not only the laws of the mechanism of distribution of 

 hereditary luoits, but aho the iiiiLs between the gene and the actual 



