Jacob Burckhardt, speaking of the Renaissance, says: “The greatest possible praise which could be given to the Italian women-celebrities of the time was to say that they were like men in brains and disposition!” The virile deeds of women recorded in the epics, especially those of Boiardo and Ariosto, show the ideal of the time. To call a woman a “virago” nowadays would be a doubtful compliment, but it originally meant an honour. Women were first allowed on the stage in the sixteenth century, and actresses date from that time. “At that period it was admitted that women were just as capable as men of embodying the highest possible artistic ideals.” It was the period when panegyrics on the female sex were rife; Sir Thomas More claimed for it full equality with the male sex, and Agrippa von Nettesheim goes so far as to represent women as superior to men! And yet this was all lost for the fair sex, and the whole question sank into the oblivion from which the nineteenth century recalled it. Is it not very remarkable that the agitation for the emancipation of women seems to repeat itself at certain intervals in the world’s history, and lasts for a definite period? It has been noticed that in the tenth, fifteenth, and sixteenth, and now again in the nineteenth and twentieth centuries, the agitation for the emancipation of women has been more marked, and the woman’s movement more vigorous than in the intervening periods. It would be premature to found a hypothesis on the data at our disposal, but the possibility of a vastly important periodicity must be borne in mind, of regularly recurring periods in which it may be that there is an excess of production of hermaphrodite and sexually intermediate forms. Such a state of affairs is not unknown in the animal kingdom. According to my interpretation, such a period would be one of minimum “gonochorism,” cleavage of the sexes; and it would be marked, on the one hand, by an increased production of male women, and on the other, by a similar increase in female men. There is strong evidence in favour of such a periodicity; if it occurs it may be associated with the “secessionist taste,” which idealised tall, lanky women with flat chests and narrow hips. The enormous recent increase in a kind of dandified homo-sexuality may be due to the increasing effeminacy of the age, and the peculiarities of the Pre-Raphaelite movement may have a similar explanation. The existence of such periods in organic life, comparable with stages in individual life, but extending over several generations, would, if proved, throw much light on many obscure points in human history, concerning which the so-called “historical solutions,” and especially the economic-materialistic views now in vogue have proved so futile. The history of the world from the biological standpoint has still to be written; it lies in the future. Here I can do little more than indicate the direction which future work should take.