52 THE GENETIC AND THE OPERATIVE EVIDENCE 



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 yeUow female 

 with a yellow male. The result was as follows: 



"**^ '^ \YeUow 9 31 ^^"'''^ '^ \YeUow 9 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 expUcable 

 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 : 



■"^ 'Sf.;;::::::: ^ ^^ tt.f^::::::: f, 

 ^-'fe'-,:::::::::: tl ™*"fef ;,::::::: ?l 



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 experi- 

 ment, 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 sitviation, 



Mayer's experiments with the large moth Callosamia promethea 

 furnish important information as to the factors involved in mating. 

 The results are all the more significant from our present point of view 

 because the colors of male and female are in this species markedly 

 different. The wings of the male are black, those of the female reddish 

 brown; the antennae of the male are large and bushy, those of the 

 female small and slender. Mayer found that the males are attracted 

 by the female from some distance when the latter are put into a glass 

 jar covered by only coarse mosquito-netting, but if the same jars are 

 turned upside down the males are unable to find the female. Females 



