the sebaceous glands on the face and elsewhere are the vestiges
of former hairs and survive from a period when the whole body was
hairy, they also tend to experience in an abortive manner this
same impulse. Thus, we may say that, with the development of the
sexual organs at puberty, there is correlated excitement of the
whole pilo-sebaceous apparatus. In the regions where this
apparatus is vestigial, and notably in the face, this abortive
attempt of the hair-follicles and their sebaceous appendages to
produce hairs tends only to disorganization, and simple
_comedones_ or pustular acne pimples are liable to occur. As a
rule, acne appears about puberty and dies out slowly during
adolescence. While fairly common in young women, it is usually
much less severe, but tends to be exacerbated at the menstrual
periods; it is also apt to appear at the change of life. (Stephen
Mackenzie, "The Etiology and Treatment of Acne Vulgaris,"
_British Medical Journal_, September 29, 1894. Laycock [_Nervous
Diseases of Women_, 1840, p. 23] pointed out that acne occurs
chiefly in those parts of the surface covered by sexual hair. A
lucid account of the origin of acne will be found in Woods
Hutchinson's _Studies in Human and Comparative Pathology_, pp.
179-184. G.J. Engelmann ["The Hystero-neuroses," _Gynæcological
Transactions_, 1887, pp. 124 et seq.] discusses various
pathological disorders of the skin as reflex disturbances
originating in the sexual sphere.)

The influence of menstruation in exacerbating acne has been
called in question, but it seems to be well established. Thus,
Bulkley ("Relation between Certain Diseases of the Skin and the
Menstrual Function," _Transactions of the Medical Society of New
York_, 1901, p. 328) found that, in 510 cases of acne in women,