There are some diseases to which women are especially liable, others which occur by preference in men. To some extent, indeed, this is explained by the special exposure of one sex or the other to certain noxious influences. The neuroses that appear as the sequelae of injuries are especially common in the male sex, because the occupations of men expose them more than women to injuries of all kinds. Of such cases, of course, we do not speak here. But there are some unquestionably hereditary morbid tendencies which manifest themselves by preference in one sex or the other, and such sexual predisposition shows itself even in childhood. I propose to give instances of this; some quoted from Moebius,[18] some from other authors, and some taken from my own personal experience. Chlorosis is a disease of feminine youth, but very often makes its appearance in childhood, especially towards the end of the second period of childhood, at this earlier age, also, attacking girls in preference to boys. Haemophilia, on the other hand, and also certain hereditary forms of muscular atrophy, occur chiefly in males, and this in early childhood. Diabetes is principally a disease of adults, but occasionally it is met with in children also; among adults, there is a considerable preponderance of males affected with this disease when diabetes occurs in childhood, the disease also exhibits a preference for the male sex, although at this time the peculiar sex-incidence is less marked than in later life. Congenital defects of the heart are commoner in boys, the proportion obtained from a very large number of cases of this kind being 61.6 boys: 38.4 girls. Chorea (St. Vitus's dance) affects girls more often than boys, the ratio in this case being 2.5 girls: 1 boy. In the case of whooping cough, we find that two girls suffer for every one boy. As regards circumscribed facial atrophy, which usually begins during childhood, a preponderance of the disease in the female sex is also noticeable. Hysteria was formerly regarded as a typically feminine disease, and although this view has now been shown to be erroneous, the fact remains that girls and women are far more often affected than boys and men. As regards hysteria in childhood, Bruns[19] states that the ratio of girls affected is to boys affected as 2:1. It is interesting to note that in the earlier years of childhood, prior, that is to say, to the age of nine years or thereabouts, no marked difference exists in the sex incidence of hysteria, the cases being distributed in the proportion, 55 per cent. girls, 45 per cent. boys; but after the age of nine, the proportion of girls affected with hysteria increases, while that of boys diminishes. Eulenburg,[20] indeed, records 17 cases of hysteria, affecting children at ages nine to fourteen years; of these nine were boys, and eight girls. Clopatt, on the other hand, collected from the literature of the subject 272 cases of hysteria in young children, 96 being boys, and 176 girls.