With the onset of puberty there is seen, also, a change in the external appearance of the individual and the attributes of virility—e.g., moustache, hair in the pubic region, alteration of the voice, etc., appear. In the female the development of the breast, hair on the pubis, etc., occurs. At the same time the features attain the peculiar characteristic which distinguishes the male face from the female, even without the aid of a moustache. In those persons in whom puberty has not occurred at the usual age (fourteen to sixteen years in our climate) the attributes of sex are absent. In these cases the male looks very much like the female. A similar phenomenon may be seen in women after castration and the climacteric, when they may even show a tendency to develop a moustache and hair on their face in places, corresponding to the male beard. This we can also observe in women whose ovaries have been altered by disease or by sexual excesses. These attributes of sex are also called external sexual characteristics, and they are the direct result of the internal secretion of the sexual glands. They only develop through the presence of such a secretion, and this is easily demonstrated by the fact that after castration of the infant, they do not appear at all. Hence, if we see grown-up men with no trace of a moustache it may indicate an undeveloped condition of the testicles. Again, we castrate a young cock, he will not grow a comb and spurs, and other cocks will pass by, too proud to fight with a degenerate deprived of its male attributes. If we now take the extirpated testicle of such cock and graft it under his skin, the other cocks will commence to fight with him, for his comb and spurs will develop as in other normal cocks. That the whole external appearance of a castrated animal or man is changed, is also demonstrated by important changes in the skeleton and size of such animals or persons. As Poncet[30] has shown, the extremities of a castrated rabbit become abnormally long, and it is a well-known fact that eunuchs have abnormally long arms and legs. This also occurs in cases of infantilism, which, as we know, is due to a non-development of the sexual glands. Moreover, the thyroid of such individuals is also found to be in a pathological condition, as was shown by Hertoghe. Footnote 30: Poncet: C. R. de la Société de biologie de Paris, 55. Men who have been castrated before puberty or whose testicles are undeveloped, present such an external appearance. They have no moustache, as above mentioned; their hair is dry and brittle and remains short; their faces are pale, and of a yellowish hue; their hands are cold and reddish blue. Often the skin of the face is like parchment and has many wrinkles. Their intelligence is often diminished, as we will show later on, and they are usually anæmic.