| First generation. | Second generation. | |||||
| Reference. | Wild-type ♀ ♀. | Bow ♂ ♂. | Reference. | Straight. | Not- straight. | |
| 72 C. | 22 | 19 | 3 I. | 56 | 69 | |
| 73 C. | 12 | 10 | 3.1 I. | 46 | 62 | |
| 5 I. | 22 | 21 | 5 I. | 56 | 68 | |
| 74 C. | 56 | 52 | 5.1 I. | 90 | 108 | |
| Total. | 112 | 102 | Total. | 248 | 307 | |
In this case the F2 expectation is 6 straight to 10 not-straight. Since the sex-linked gen bow entered from the female, half the F2 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.
In order to study the linkage of lemon, the following experiment was carried out. Since it was impracticable to breed directly from the lemon flies, virgin females were taken from stock throwing lemon, and were mated singly to cherry vermilion males. Only a few of the females showed themselves heterozygous for lemon by producing lemon as well as gray sons. Half the daughters of such a pair are expected to be heterozygous for lemon and also for cherry and vermilion, which went in from the father. These daughters were mated singly to cherry vermilion males, and those that gave some lemon sons were continued,
and are recorded in table 24. The four classes of females were not separated from each other, but the total of females is given in the table.
Table 24.—P1 lemon (het.) ♀ × cherry vermilion ♂ ♂. F1 wild-type ♀ × cherry vermilion ♂ ♂.
| Females. |
|
|
|
| Total ♂♂. | ||||
| Cherry ver- milion. | Lemon. | Cherry lemon. | Ver- milion. | Cherry | Lemon ver- milion. | Cherry lemon ver- milion. | Wild type. | ||
| 71 | 42 | 19 | 2 | 6 | 3 | 6 | 0 | 0 | 78 |
| 88 | 26 | 19 | 2 | 8 | 8 | 4 | 0 | 0 | 67 |
| 36 | 28 | 7 | 0 | 2 | 1 | 0 | 0 | 0 | 38 |
| 51 | 12 | 22 | 0 | 4 | 4 | 4 | 0 | 0 | 46 |
| 98 | 29 | 35 | 0 | 8 | 5 | 1 | 0 | 0 | 78 |
| 47 | 17 | 11 | 0 | 1 | 3 | 2 | 0 | 0 | 34 |
| 46 | 23 | 20 | 1 | 6 | 5 | 2 | 0 | 0 | 57 |
| 437 | 177 | 133 | 5 | 35 | 29 | 19 | 0 | 0 | 398 |
