But a host of experiments and data prove the interstitial glands to be the direct controllers of elementary sexuality and the specific sex traits of male and female. Beginning with Berthold back in the first half of the nineteenth century, who studied the fowl, a number of observations have been made on the effects of excision, translocation and transplantation of these glands. The results of the experiments and observations can be summed up as follows: if the male individual is castrated before puberty, that is, before the advent of the sexual life, secondary sex qualities do not develop. In males, the generative organs do not grow, hair on the face does not appear, hair elsewhere on the body remains generally scanty, the voice continues as high-pitched as the child's, there is more or less muscle weakness, obesity, and mental sluggishness. In other words, we have an effeminate man, technically a eunuch. In the castrated female, the pelvis does not grow to the normal feminine size, the breasts do not swell as they should, more or less hair comes out on the face, the voice is low-pitched, and tends to be rather husky, the legs are longer, and again, the mentality is dulled. That is, a masculine sort of woman is produced. In short, the castrated male takes on a feminine type, and the castrated female, a male type. In either case there is also an infantilism, a retention of the infantile mental traits, a lack of development of the adult mental attitudes and reactions. Now, if in the castrated male is transplanted an ovary, the positive characteristics of the female are evoked, such as enlarged mammary glands, and a tendency to secretion of milk. Experiments have also been reported in which a uterus was also placed in such an animal, with a means of entry, and pregnancy followed. If in the castrated female a testicle is planted, the masculine traits become much more marked and striking. A direct exchange of the male and female rôles can thus be achieved. Castration after puberty cannot modify profoundly structures like the skeleton which are already completed. Yet it may unquestionably bring about definite retrogressive changes in the secondary sex characters: reduction or loss of virility, diminution of facial and body hair, and a general presenility or hastening of senility.