1. Some of the objections that apply to the theory of natural selection apply also with equal force to the theory of sexual selection in so far as the results in both cases are supposed to be the outcome of the selection of individual, or fluctuating, variations. If these variations appear in only a few individuals, their perpetuation is not possible, since they will soon disappear through crossing. It would be, of course, preposterous to suppose that at any one time only those few individuals pair and leave descendants that have the secondary sexual characters developed to the highest point, but if something of this sort does not occur, the extreme of fluctuating variations cannot be maintained. Even if half of the individuals are selected in each generation, the accumulation of a variation in a given direction could not go very far. The assumption, however, that only half of all the individuals that reach maturity breed, and that all of these are chosen on account of the special development of their secondary sexual characters, seems preposterous. Furthermore, if it is assumed that the high development of the new character appears in a large number of individuals, then it is not improbable that its continued appearance might be accounted for without bringing in, at all, the hypothesis of sexual selection. 2. But even supposing that the females select the most beautiful males, then, since in the vast majority of higher animals the males and the females are in equal numbers, the others will also be able to unite with each other in pairs after this first selection has taken place. Nothing will therefore be gained in the next generation. It is interesting to see how Darwin attempts to meet this argument. He tries to show in the case of birds, that there are always unpaired individuals, but since the few facts that he has been able to collect show that there are as many additional females as males, the argument proves too much. A few species are polygamous, one male having a number of female birds; but on this basis we can only account, at best, for the development through competition of the organs of offence and defence used to keep away the weaker males. Yet it is just amongst these birds that we often find the ornamental characters well developed. In fact, since all the females in such cases are selected, and since they will transmit the characters of all the males, it is evident that the secondary sexual characters could not be formed in the way imagined.