=Formation of the sexual glands.=--We must remember that at a very early embryonic period certain groups of cells are reserved to form later on the sexual glands. These cells are at first neither male nor female, but are undifferentiated; later on they become differentiated to form in certain individuals, called males, the testicles with their spermatozoa, and in others, called females, the ovaries with their eggs. On this differentiation depends the sex of the individual, and, according as it takes place in one way or the other, all the rest of the body develops with the correlative sexual characters of the corresponding sex (at first the external genital organs peculiar to each sex, then the beard in man, the breasts in woman, etc). =Castration. Correlative sexual characters.=--Castration is the term applied to the extirpation of the sexual glands. When it takes place in infancy it causes a considerable change in the whole subsequent development of the body, especially in man, but also in woman. Man becomes more slender, preserves a high and infantile voice, and his sexual correlative characters develop incompletely or not at all. _Eunuchs_ are men castrated, usually in infancy. To ensure more safety in their harems the Orientals not only remove the testicles but also the penis. Bullocks and horses are bulls and stallions castrated at an early age, and can be distinguished at first sight from normal males. Females who have undergone castration become fat and sometimes take on certain masculine characters. Male human eunuchs have a high-pitched voice, a narrow chest; they remain beardless or nearly so, and have an effeminate character, often intriguing. In both sexes there is a tendency to neurosis and degeneration. It is a mistake to qualify the peculiarities of the male eunuch in the terms of female peculiarities; there is only a relative tendency. The eunuch is no more a woman than a bullock is a cow. The characters of castrated individuals are due only to ablation of the sexual glands themselves--the testicles in man and the ovary in woman; mutilation of other sexual organs, internal or external, such as the penis, womb, etc., produces no result of this kind. It would even appear to result from recent experiments that reimplantation of a sexual gland in any part of the body is sufficient to arrest the production of the special peculiarities of the eunuch.