RELATING TO SECONDARY SEXUAL CHARACTERS. 51 



have found out the most probable result after the first attempt through 

 "associative memory" is in accord with what the study of "animal 

 behavior" has shown to be possible. In this sense purpose would mean 

 a hne of conduct that experience had shown to lead to a certain end. 

 Anticipation or far-sightedness would henceforth characterize such a 

 reaction. Here, however, we venture on very dubious grounds. But 

 the display of the male may be purposeful in a much simpler sense. 

 His activity may be an inborn reflex to visual or other sensory stimuli 

 that is a part of his attack on the female, or possibly a series of reflexes 

 that we may register under the old unanalyzed terms of "desire and 

 fear." The action calls forth a responsive reflex in the female, for 

 the sexual act is not entirely active on one side, passive on the other, 

 but consists of a series of interreactions on the part of each sex, which, 

 if they pursue a given course, leads to the final mating. The mutual 

 responses appear to follow an automatic course in many cases if the 

 individuals are sexually ready to mate and the environment is pro- 

 pitious. Types of behavior of this kind must be familiar to anyone 

 who has observed domesticated and semi-domesticated animals. The 

 purpose of the display may mean no more than a reaction that leads 

 to a result propitious to the perpetuation of the species if the situation 

 is ripe for such an outcome. 



This conclusion still leaves open the question as to whether the 

 display is more likely to be successful, if certain special characters 

 possessed by the species are exhibited. In the absence of any sufficient 

 evidence to show that this is so, and in the Hght of the very great danger 

 of projecting "our human standards" into the world of other animals, 

 and in view of the fact that related species without such marks are as 

 successful in maintaining themselves, I can not but think that at 

 present we have a good deal to lose in the way of scientific procedure 

 and nothing to gain of scientific value in accepting Darwin's inter- 

 pretation of sexual selection based on the display of the male as fur- 

 nishing an opportunity to the female to make the "best" selection 

 amongst her suitors on the basis of his adornment. 



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 



