STUDIES ON THE GEXKTICS OF FLOWER-COLOUBS, ETC. 



Ill 



statetl. We have tberefore pnnou that we have in F, the ratio 9 magentas : 3 

 oranges : 4 whites, ami we see tliiit in this generation we ]iave the complete 

 liukfige of JB and ß just as in Cross V. 



Tliiit the 7-,-hyl)ricl under discussion produces the gametes CRli, cJtJi, 

 Crb, crb, but not CrJi, crTi, CRh, Clib (except very rai-e cases, s. Table 

 VI, B), will be seen also by crossing it back by white-I (ccrrbb), i. e. that 

 variety which contains neither C nor Ji nor JS, thus, for instance, this 

 crossing -was done in 1919, and wo had in 1920 : — 



This cross indicates us clearly what kinds of gametes are i^roducad by 

 the i^i-hybrid, and h'oni tlie results we sea that JS and R are completely 

 linked to each other, because if the fi'ee assortment were the case, we should 

 ]la^ e the ratio 1 magenta : 1 red : 2 oranges : 4 whites instead of tliat 1 

 magenta : 1 orange ; 2 whites, as it was actually the case. 



The experiment of Miss Tasui on the crossing of white and ]pale yellow, 

 giving ris3 to magenta i^^-plants,^ seams to agi'ee with my present cross in 

 ssveral respects, though she has used pale yellow instead of orange. Though 

 lier expariment ends with F,, the actual numbers of magentas, yellows and 

 whites in the latter generation accords pretty well vdth the expected, and 

 there wül be perhaps no doubt that she had to deal in this generation Mith 

 the 9:3:4 segi-egation. Her explanation in respact to the appearance of 

 magentas in F^ agi-eos also with what I have above stated about the same 

 phenomenon ; the difference between her view and mine lies however in the 

 fact that while she considei-s tha magenta colom- to be due to one single factor 

 jB (in co-operation with C), I regard the same colour to be due to the factor- 

 complex RR (naturally in co-oparation with C). Though fi-om the analogy 

 with several cases studied till now by many authore the combined action of 

 some such feictore for the production of the magenta colour seemed to me a 



' Bot. Mmj., Tokyo, Vol. 34, 11«), i>i\ 59-63. 



