A OENETico-rHYsroLooicAL sTi'ny ON' Tirr. r )n>r.vTioN etc. 



51 



TliJ piu'ple and IJiie pigmoute are iintliocyanins. Botli anthocyaniu ami 

 brown pigments are coufiued to the epidermis existing in the same cell. 

 Wlieii a common black bean ls boiled with an allailine solution, the colour 

 of the solution becomes blue to gi-ceu at first, but soon changes to deep wine 

 red owing to the extraction of the brown pigment in alkali. 



Tlie poi-oxidase wjis tested in a number of varieties at the stages previous 

 to pigmentation of the seed coat. Tlie reaction was very distinct in the seed 

 coat of all the coloured types as well as in the yellow and gi-eeu ones, but 

 the direct oxidase reaction failed by alplia uaphtol, l^nzidine, myiicetin and 

 guiiiacum. It was ofk-n noted when alpha naphtfjl was apj)lied, the reaction 

 was veiy faint in the epidermis even in the presence of hyctogen peroxide. 

 Tliere could be fimnd no definite diiferenca with respect to the peroxidase 

 reacHou exliibited by the seed coat? of beans which contain the chromogenic 

 substance and those lacking it; 



In the black patched Ijean, however, the part where the anthocyanin 

 coloin- will ajipear in a patch, jielded a deep pm-ple or bro^ni colom- by 

 immersing the whole bean which was previously ti-eated with alcohoUc solution 

 of benzidiue or nnnicetin, in a dilute solution of hydrogen peroxide. Tlie 

 remaining part where anthocyaniu will injt be formed at all, yielded less 

 distinct colour in the case of benzidine and nearly failed in the case of 

 mpicetin. The chromogenic substance was detected in the tissue of the n(ju- 

 IjLick part. Tlie alcoholic extract of the portion gave a slight red colour by 

 heating with hydnx;liloric acid. 



The above oljseiTation seems to point out the fact that at the time of 

 pigment formation, the black patched portion of the seed coat contains more 



