Hair as a rule grows more or less in length as the wearer grows in
age; chiefly the hair on the head, then that in the beard, and fine
hair grows longest of all. With some people as they grow old the
eyebrows grow thicker, to such an extent that they have to be cut off;
and this growth is owing to the fact that the eyebrows are situated at
a conjuncture of bones, and these bones, as age comes on, draw apart
and exude a gradual increase of moisture or rheum. The eyelashes do
not grow in size, but they shed when the wearer comes first under
the influence of sexual feelings, and shed all the quicker as this
influence is the more powerful; and these are the last hairs to grow
grey.