Now when a Duke of Westminster is mated with a Painted Lady the factor for erect standard (E) is brought in by the red, and that for blue (B) by the Duke, and the offspring are consequently all purple bicolors. Purples so formed are all heterozygous for these two factors, and were the case a simple one, such as those which have already been discussed, we should expect the F_2 generation to consist of the four forms: erect purple, hooded purple, erect red, and hooded red in the ratio 9 : 3 : 3 : 1. Such, however, is not the case. The F_2 generation {90} actually consists of only three forms, viz. erect red, erect purple, and hooded purple, and the ratio in which these three forms occur is 1 : 2 : 1. No hooded red has been known to occur in such a family. Moreover further breeding shows that while the erect reds and the hooded purples always breed true, the erect purples in such families _never_ breed true, but always behave like the original F_1 plant, giving the three forms again in the ratio 1 : 2 : 1. Yet we know that there is no difficulty in getting purple bicolors to breed true from other families; and we know also that hooded red sweet peas exist in other strains. Painted Lady x Duke of Westminster (erect red) | (hooded purple) | Purple Invincible (erect purple) | +-------------+-----------------+ | | | Painted Purple Invincible Duke of Lady Westminster (1) (2) (1) EEbb eeBB Parents /\ /\ / \ / \ / \ / \ Eb Eb eB eB gametes \------------/ EeBb F_2 ____/ \____ / \ Fem. gametes of F_1 Eb ---> EEbb <--- Eb Male gametes of F_1 Eb ---> EeBb <--- eB eB ---> EeBb <--- Eb eB ---> eeBB <--- eB \----/ F_2 generation