An excellent opportunity to study the problem as to “choosing” by the female is furnished by the mutant races of _Drosophila_, some of which, differing in a single mutant gene, have wings as different in coloration as black, yellow, or gray, and eyes as differently colored as white, vermilion, or red. Sturtevant put a yellow female with a gray (wild-type) male and a yellow male. The male that first mated was noted and the trio discarded. The female “chose” the gray males 25 times and the yellow only 8 times. In the control combination, where a gray female “chose” between the same two kinds of males, she took the gray male 60 times and the yellow male 12 times. In both cases it “appears” that the female “prefers” the gray male, but this deduction may give an entirely wrong impression as to what is taking place, for the result would be the same in kind if the gray male were more active and mated quicker. This was tested by putting a gray and a yellow female with a gray male and then for control a gray and a yellow female with a yellow male. The result was as follows: Red ♂ {Gray ♀ 25 Yellow ♂ {Gray ♀ 12 {Yellow ♀ 31 {Yellow ♀ 30 Here the gray male mated slightly oftener with the yellow female than with the other, whereas the yellow male mated much oftener with the yellow female than with the gray one. Both results are explicable on the view that the yellow female, being less active, is more easily captured by the yellow male than is the gray female. This view fits in also with the former experiment, where the yellow male is much less successful than the more active gray male. Such a conclusion gives a more consistent explanation of all the facts than does the theory of female choice, for on the latter we must suppose that the yellow females prefer the gray males and the yellow male prefers the yellow females, etc. The following results were obtained by Sturtevant when red and white eyed flies were competing: Red ♂ {Red ♀ 54 Red ♀ {Red ♂ 53 {White ♀ 82 {White ♂ 14 White ♂ {Red ♀ 40 White ♀ {Red ♂ 62 {White ♀ 93 {White ♂ 19 The outcome can be interpreted in the same way as the yellow-gray competition. The red male wins by virtue of his greater activity, while the white female is chosen more often, especially by the white male, because of her passivity (or weaker resistance). It may be claimed that these results do not show that the female does not choose, for such choice, if made, would be swamped by another condition of the experiment, viz, the greater aggressiveness of one kind of male and greater passivity of the other kind of female. This, of course, is true, but the experiment still shows that in these flies other influences are so much greater than “choice” by the female, if it exists, that the postulated effect of the latter practically disappears from the situation.