For, in the first place, the differences between women are much greater than appear when, for instance, we read history as history is at present understood, or when we observe and compare the world and his wife. Uniformity or comparative uniformity of environment is a factor of obvious importance in tending to repress the natural differences between women. Reverse the occupations and surroundings of the sexes, and it might be found that men were "much of a muchness," and women various and individualized, to a surprising extent. But, even allowing for this, it is difficult to question that men as individuals do differ, for good and for evil, more than women as individuals. Such a malady as haemophilia, for instance, sharply distinguishes a certain number of men from the rest of their sex, whereas women, not subject to the disease, are not thus distinguished, as individuals. But the very case here cited serves to illustrate the fallacy of studying the individual as an individual only, and teaches that there is a second reason why the selection of women for motherhood is more important than is so commonly supposed. In the matter of, for instance, haemophilia, men appear sharply contrasted among themselves and women all similar. Yet the truth is that men and women differ equally in this very respect. Women do not suffer from haemophilia, but they convey it. Just as definitely as one man is haemophilic and another is not, so one woman will convey haemophilia and another will not. The abnormality is present in her, but it is latent; or, as we shall see the Mendelians would say, "recessive" instead of "dominant." Now I am well assured that if we could study not only the patencies but also the latencies of individuals of both sexes, we should find that they vary equally. Women, as individuals, appear more similar than men, but as individuals conveying latent or "recessive" characters which will appear in their children, especially their male children, they are just as various as men are. The instance of haemophilia is conclusive, for two women, each equally free from it, will respectively bear normal and haemophilic children; but this is probably only one among many far more important cases. I incline to believe that certain nervous qualities, many of great value to humanity, tend to be latent in women, just as haemophilia does. Two women may appear very similar in mind and capacity, but one may come of a distinguished stock, and the other of an undistinguished. In the first woman, herself unremarkable, high ability may be latent, and her sons may demonstrate it. It is therefore every whit as important that the daughters of able and distinguished stock shall marry as that the sons shall. It remains true even though the sons may themselves be obviously distinguished and the daughters may not.