A GEN*ETTCO-PHYSIOLOGICAL STUDY ON THE FORMATION ETC. 



69 



In the case of the oi-oss " Waremame " x " Acliuiuuri " iu ^\ hicli biili" 

 and black ivve ci'ossed, two paii-s of genes are concerned in the formation of 

 four typas of seed coat, i.e., self black, imperfect black, brown and biiß". If 

 we let a pair of genes C and c stand for 'the chromogens, imperfect black 

 wivs fonnd to can-y no C, in spite of the fact that the gi'ound-coloiu" appeared 

 to be brawn, as already mentioned, henca we may assume that the full 

 development of the deep purple authocyanin pigment is only possible by the 

 presence of C and R. The gene for the formation of the chromogenic 

 substance may therefore have a simxdtaueous action on the formation of brown 

 and self black from the same chromogenic substance. Here the gene G is 

 not concerned. The parental plants may have the follovtdng genotypic com- 

 position with resp3ct to the coloiu- of the seed coat : 



Self black CCOOREiigg 



Bufl* ccOOrriiyrj 



The F^ plant is heterozygous to C and R, and in F^ we shoidd expect 

 the following families : 



The actual numbers observed are as follows. 



