+--------------------------------------------+ | First generation. | |----------+------------------+--------------+ |Reference.| Wild-type | Bow | | |[female] [female].|[male] [male].| |----------+------------------+--------------+ | 72 C. | 22 | 19 ~ | 73 C. | 12 | 10 ~ | 5 I. | 22 | 21 | | 74 C. | 56 | 52 | | |------------------+--------------+ | Total.| 112 | 102 | +----------+------------------+--------------+ +------------------------------+ | Second generation. | +----------+---------+---------+ |Reference.|Straight.| Not- | | | |straight.| +----------+---------+---------+ ~ 3 I. | 56 | 69 | ~ 3.1 I. | 46 | 62 | | 5 I. | 56 | 68 | | 5.1 I. | 90 | 108 | +----------+---------+---------+ | Total.| 248 | 307 | +----------+---------+---------+ In this case the F_2 expectation is 6 straight to 10 not-straight. Since the sex-linked gen bow entered from the female, half the F_2 males and females are bow. The half that are not-bow consist of 3 straight to 1 arc, so that both in the female classes and in the male classes there are 3 straight to 5 not-straight or in all 6 straight to 10 not-straight. The realized result, 248 straight to 307 not-straight, is more nearly a 3:4 ratio, due probably to a wrong classification of some of the bow as straight. LEMON BODY-COLOR. (Plate I, figure 3.) A few males of a new mutant with a lemon-colored body and wings appeared in August 1912. The lemon flies (Plate II, fig. 3) resemble quite closely the yellow flies (Plate II, fig. 4). They are paler and the bristles, instead of being brown, are black. These flies are so weak that despite most careful attention they get stuck to the food, so that they die before mating. The stock was at first maintained in mass from those cultures that gave the greatest percentage of lemon flies. In a few cases lemon males mated with their gray sisters left offspring, but the stock obtained in this way had still to be maintained by breeding heterozygotes, as stated above. But from the gray sisters heterozygous for lemon (bred to lemon males) some lemon females were also produced. LINKAGE OF CHERRY, LEMON, AND VERMILION.