Hairs if plucked out before maturity grow again; but they do not
grow again if plucked out afterwards. Every hair is supplied with a
mucous moisture at its root, and immediately after being plucked out
it can lift light articles if it touch them with this mucus.

Animals that admit of diversity of colour in the hair admit of a
similar diversity to start with in the skin and in the cuticle of
the tongue.

In some cases among men the upper lip and the chin is thickly
covered with hair, and in other cases these parts are smooth and the
cheeks are hairy; and, by the way, smooth-chinned men are less
inclined than bearded men to baldness.

The hair is inclined to grow in certain diseases, especially in
consumption, and in old age, and after death; and under these
circumstances the hair hardens concomitantly with its growth, and
the same duplicate phenomenon is observable in respect of the nails.