=For this reason, all attempts, whether initiated by some natural process or by some intentional guidance of the process of civilization, towards the obliteration of the distinction between the specific masculine and the specific feminine, must be regarded as futile, and as antagonistic to the process of development.= The production of the so-called “third sex” is unquestionably a step backwards. For bisexual differentiation is an =advance= upon the more primitive form of sexual differentiation in which both the male and the female sexual elements were produced by a single individual (=hermaphroditism=). In the phylogeny of the human species unilateral sexual reproduction gave place to the bilateral type, the reproductive elements being formed within the bodies of two =distinct= individuals--the sperm cells within the body of the male, the germ cells within the body of the female. In this manner originated the contrast between the individuals of the two sexes, or bisexual differentiation, which, in the course of phylogenetic development, has become continually more definite, more extensive, and more characteristic, through the operation of the principle of =sexual selection=; and thus by inheritance and adaptation the mental and physical characteristics of sexuality, primitive and superadded, have gradually become defined and fixed. In the higher ranks of the animal kingdom and in the human species, this =heterosexuality= has, through inheritance, become continually more sharply defined; but the traces of the primitive hermaphroditic state have never been wholly obliterated. Love in the human species is manifested by pairing. Such is the normal condition, and the =only= condition in harmony with the progressive tendency towards perfection. But remnants of hermaphroditism, of bisexuality in a single individual, of the “third sex,” are to be found in every human being, and are disclosed by embryology and comparative anatomy in the form of vestiges of female reproductive organs in the male and of male reproductive organs in the female. Herein exists an indisputable proof of the originally hermaphrodite nature of the human ancestry. But these female organs in the male body, and their converse, the male organs in the female body, are =stunted=, are rudiments merely; whereas in the course of evolution the masculine reproductive organs of the male and the feminine reproductive organs of the female have been more and more powerfully developed, and more and more sharply differentiated in type, until they have come to constitute the expression of the specific differences between man and woman. They alone represent the more advanced stage. Moreover, these vestiges of an early hermaphroditic condition are in the human species far less extensive than in other mammals; and the sexual discrepancy in the human species, as compared with the lower animals, becomes still more noticeable when we take into account the fact that certain parts of the reproductive