In the skin, remark _Spietschka_ and _Grünfeld_, a new life begins at the time of the development of puberty, and it is this which first gives to human beings the external characteristics of sexual maturity. In certain regions which have hitherto been covered only by fine downy hairs,[27] thick, strong hairs develop, and at the same time the general growth of hair becomes more active. These regions are, the genital region, and the axillæ. This increased growth of hair is accompanied by a stronger secretion of the sebaceous glands, which very often is in excess of actual requirements, and may thus lead to cosmetic disturbances and to various diseases of the skin. Thus arise the various forms of seborrhœa.[28] The commonest of these is the formation of comedones, which, at the time of puberty, may make their appearance especially on the nose, the forehead, and below the corners of the mouth, but also on other parts of the face or on the back and the breast; in those regions, that is to say, in which the sebaceous glands attain a considerable size. The retention of the sebum may give rise to inflammation, which the access of micro-organisms converts into suppuration. Thus arises acne vulgaris. In another form of seborrhœa,[28] the secretion is more fluid in consistence, and collects on the surface of the skin, furnishing this with an oily covering—seborrhœa oleosa.[28] This most commonly occurs on the face; if the fatty layer is removed, the skin remains dry for a brief period only, and soon becomes greasy and shiny once more. Dust readily adheres to the greasy surface, and this gives the face a dirty appearance. Seborrhœa faciei is readily converted into eczema. With the puberal development of the external genital organs is associated an increase in the sebaceous secretion of these regions. On the clitoris and its prepuce, and on the folds and in the furrows of the vulva, in consequence of insufficient cleanliness, an accumulation of sebum and cast-off epidermic scales readily occurs; such an accumulation may become rancid, may irritate the skin, and may thus give rise to erosions and to purulent secretion. In chlorotic girls at the time of puberty, on account of the anæmic condition of the blood, eczema is not uncommon, especially on the hands and the face. On the face, or on the forehead, red papules appear on circumscribed areas, and become vesicular; raw, weeping spots are thus formed, and have a very disfiguring appearance. Such eczema may occur also in connection with disturbances of menstruation, when the menses are scanty and pale, or when dysmenorrhœa is present.