22 Bulletin 392 



R but contained both X and I. The Fi magenta, then (or dark mauve), 

 would be of the constitution CCRrXXII or with I simplex. Such a plant 

 could throw magentas, light magentas (or dark mauves), mauves, tinged 

 whites, and whites. 



White crossed with light blue. — The Fi in cross 133 consisted of 2 light 

 purples, and in cross 158 of i light purple. Light purples could result 

 from a cross between white and light blue if the white parent brought 

 in the gene I. 



If the light blue parent is simplex for R, white as well as light blues 

 will appear in the Fi, as was the case in crosses 116, 152, 154, 155, 

 and 157. 



White crossed with dark blue. — In cross 104 the Fi consisted of 5 dark 

 blues and the F2 of 15 dark blues. Such a result might occur in a cross 

 between white and dark blue if the white parent carried the genes B 

 and X in duplex condition but lacked only R. One-third of the F2 plants 

 would be expected to be whites, as in the following schema: 



Fi F2 



CCRRBBXX dark blue ( RRBBXX dark blue 



X CCRrBBXX dark blue Cc] RrBBXX dark blue 



CCrrBBXX white [ rrBBXX white 



If the white parent carries the gene I, light purples will constitute 

 the Fi, as in cross 221. The light purple plant obtained from this cross 

 gave 8 purples and i dark blue. 



In cross 220 the Fi consisted of 5 light blues, which gave an F2 progeny 

 of I dark blue, i light blue, i pink, and 2 whites. This might result 

 from a cross in which both parents lacked the gene I. 



White crossed with dark purple. — Only three crosses are recorded between 

 white and dark purple. The offspring were all either dark purple or light 

 purple. In F2 they broke up into all the hypostatic types, as would be 

 expected if many or all of the genes were simplex. 



In cross 162 four of the dark purple Fi plants that were selfed bred true, 

 but the fifth threw purples, light purples, light blues, and whites. 



Type 2 Tinged white 



Tinged white crossed with light blue. — In cross 150 a light blue was 

 mated with a tinged white. The Fi plants consisted of 2 mauves. To 

 make it possible for these mauves to appear, the blue parent must have 

 been simplex for B, so that it dropped out in these Fi combinations. 

 If larger numbers had been obtained, light blues and tinged whites would 

 also have been expected, but no true whites, since R would always be 

 present at least in sim])lex condition. 



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