The behavior of the male under sexual excitement is often described to be of a kind to exhibit before the female his peculiar adornments. That the “purpose” of his exhibition is to show himself off before the female may be conceded, with reservations as to what is meant here by “purpose.” That the male is conscious of the probable results of his conduct is scarcely probable the first time he courted; but that he may 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 line 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 propitious. 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 light 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 interpretation of sexual selection based on the display of the male as furnishing an opportunity to the female to make the “best” selection amongst her suitors on the basis of his adornment.