The antics of male birds at the mating season, their courtship so-called, has played an important rôle in Darwin’s theory of sexual selection. The behavior of many birds at this time is of such a kind as to suggest that the male is exhibiting his plumage before the female for the “purpose” of influencing her choice. The whole paraphernalia of human psychology is imported into the situation and both the consciousness of the male, his intentions so to speak, and the supposed esthetic response or choice of the female is invoked. Even though it be granted that the words that we must make use of, borrowed from human behavior, are such as to imply much more in the direction of consciousness and purpose than is desirable, and that most of the behavior of animals should be stated in a more roundabout and objective way, yet the theory will only work out on the assumption that the female _chooses_ in some sense the more brilliant or ornamental (or effective) male, whether she is “conscious” or unconscious of intention. I doubt if anyone to-day would care to defend seriously the theory on the grounds of consciousness or esthetic value of the exhibition, despite the fact that Darwin’s language often takes this turn and the less-guarded statements of some of his disciples, such as Romanes, show little hesitation in anthropo-morphologizing the entire situation. It is, however, not necessary for the working out of the theory that this complication be introduced into it, for if the female is more likely to mate with a more brilliantly colored than a less brilliantly colored male, the theory may be made to apply regardless of whether she is “conscious” or not of the difference to which she responds. But there are weighty arguments against such an interpretation of the behavior of the male and female during courtship. In the first place, there is almost no direct evidence to show that the female mates with the more ornamental male. As this is the all-essential requirement of the theory, the almost complete absence of facts in its support leaves the theory resting on a theoretical assumption. It can scarcely pass unnoticed that while there exists a large mass of data describing the secondary sexual characters, there is practically nothing in this accumulation to show that the female makes her selection on differences in coloration or ornamentation. And on the other hand, there is some evidence showing that the female is ready to succumb to the aggressiveness of the male rather than that she “chooses” him.