Sex-linked Inheritance in Drosophila

by Thomas Hunt Morgan; Calvin B. Bridges

LINKAGE OF CHERRY AND VERMILION.

The cross-over value for white (eosin) and vermilion, based on a very large amount of data, is about 31 units. An experiment of our own in which cherry was used with vermilion gave a cross-over value of 31 units, which is a close approximation to the cross-over value of white and vermilion. The cross which gave this data was that of a cherry vermilion (double recessive) male by wild females. The F₁ wild-type flies inbred gave a single class of females (wild-type) and the males in four classes which show by the deviation from a 1:1:1:1 ratio the amount of crossing-over involved.

In one of the F₂ male classes of table 28 the simple eye-color cherry appeared for the first time (since the original mutant was vermilion as well as cherry). Safir has recorded a similar cross with like results.

Table 28.—P₁ cherry vermilion ♂ ♂ × wild ♀ ♀. F₁ wild-type ♀ ♀ × F₁ wild-type ♂ ♂.

Reference.	Wild- type ♀♀.	Non-cross-over ♂.		Cross-over ♂.		Total ♂♂	Cross- over value.
		Cherry vermilion.	Wild- type.	Cherry.	Ver- milion.
160 C	188	57	61	32	34	184	36
161 C	256	85	93	40	52	270	34
162 C	251	78	78	20	37	213	26
163 C	229	76	95	34	33	238	28
Total	924	296	327	126	156	905	31

Some cherry males were bred to wild females. The F₁ wild-type males and females inbred gave the results shown in table 29. Some of the cherry males thus produced were bred to their sisters. Cherry females as well as males resulted; and it was seen that the eye-color is the same in the males and females, in contradistinction to the allelomorph eosin, where there is a marked bicolorism (figs. 7, 8, [Plate II]). The cherry eye-color is almost identical with that of the eosin female, but is perhaps slightly more translucent and brighter.

Table 29.—P₁ cherry ♂ ♂ × wild ♀ ♀. F₁ wild-type ♀ ♀ × F₁ wild-type ♂ ♂.

Reference.	Wild-type ♀.	Wild-type ♂.	Cherry ♂.
15 I	266	120	100

COMPOUNDS OF CHERRY.