and to thus facilitate the orientation of the reader.

The second book then opens with a consideration of the hair and scalp,
and their respective disorders.

The hair is a dry fume (_fumus siccus_), escaping from the body
through the pores of the scalp and condensed by contact with the air
into long, round cylinders. It increases rather by accretion than by
internal growth, and its color depends upon the humors. Thus red hair
arises from unconsumed blood or bile; white hair, from an excess of
phlegm; black hair, from the abundance of black-bile (_melancholia_),
etc. The use of the hair is for ornament, for protection and for the
distinction of the sexes. Numerous prescriptions for dyeing the hair,
for depilatories (_psilothra_), for the removal of misplaced hair and
for the destruction of vermin in the hair are carefully recorded.

Three varieties of soaps for medicinal use are described, and the
process of their manufacture indicated. The base of each is a
lixivium made from two parts of the ashes of burned bean-stalks and
one of unslaked lime, mixed with water and strained. Of this base
(_capitellum_), two parts mixed with one part of olive oil form the
_sapo saracenicus_. In the _sapo gallicus_ the base is made with the
ashes of chaff and bean-stalks with lime, and to it is added goat's
fat, in place of the oil. The _sapo spatareuticus_ is made in a
similar manner, except that oil replaces the goat's fat and the soap
is made only during the dog days, since the necessary heat is to be
supplied by the sun alone.

Among the diseases of the scalp attention is given to alopecia,
dandruff (_furfur_), tinea caries and various pustular affections,