A GENETICO-PHYSIOLOGICAL STUDY UN THE FORMATION ETC. 



63 



In-owu. The c-hromogeuic substiiuce of the bruwu pigineut in tlio paloas was 

 tested at the time prcvions to pigiueutatiou but failed. Therefore it is evident 

 tliat the chromogenic substiuice of the browu pigment iu the palea is different 

 frnm that of the awn wliich gives risa to tlie red anthocyauin by tin action 

 of the B gene. But B has a specific relation to the formation of pm-ple 

 pigment iu the epidermis, inasmucli as the full eolnnr in the purple palea is 

 always associatefl with the brown gi'ouud-colour, and tlie loc^zed purple 

 excludes the latter. It appears therefore that either />' h-is a simultanwni^ 

 acti<jn on extending the purple pigment to the euUre surface of the palea or 

 that the phenomenon is due to another gene which is completely linked with 

 JJ. 



The formation of any pui-ple pigment in the palea appears to be due to 

 another gi"Oup of genes which are simihir in kind to that which afiected the 

 awn, inasmuch as the pm'ple awn is completely linked with any purple present 

 in the palea but no red ever occurs in the latter. Let P' be the gene for the 

 presence of pui-ple pigment in the palea, and p' for the absence of the same. 

 Further admit that P' and P are Hnked. Thus 



" Haubuu-nento " ppp'p'BB Awn red, paleas brown. 



" Genroku-raochi " PPP'Plh Awn pui-ple, paleas purple localized. 



F, " Hanb." X " Genrok." PPPp'Bh Awn piu-iJe, paleas pm-ple. 



The Fl plant is heterozygous to P' and B, since P and P are linked. In 

 F. we es].iect the following genotypes to occur ; 



We should expect therefore the following scgi'cgatiou in F^ -with respect to the 

 colora' of paleas. 



Genotype of K plant 



PPBB 1 



Segregation in F^ Kntio. 



PP Const. 



