1. The character doubleness in the
Portulaca grandiflora (at least in the races used in the present experiments), behaves dominant to the character singleness. The number of alleromorphic ids concerned appears to be one; if it is two or more, then they are situated in one and the same chromosome.
2. The pale yellow colour of the petal is due to the presence of a pigment (may be one of the flavone derivations), which serves as the chromogen for the magenta pigment. The latter will be formed by the action of a reducer upon the former. The id, concerned in the formation of this chromogen, was denoted by C and its absence by c. The petals of the individual, which lacks C, i.e. those of cc is white.
3. There are two kinds of the white-flowered individuals. The one is represented by ccRR, and the other by ccrr. Here the id R is related to the formation of the reducer, and c denotes the absence of the id C. The F
1 plant between the white ccRR and the yellow CCrr has magenta pigment in the petal; and the plants of F
2 generation appear in the ratio 9 magentas: 3 yellows: 4 whites.
4. The ids C, R, and D are sitiuated in the different chromosomes.
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