sulphate, alum, tannic or acetic acid, in the strength commonly
employed for vaginal injections, are at times curative.

In bath-pruritus weak glycerine lotions, and an ointment containing a
few grains of thymol and menthol to the ounce sometimes give moderate
relief. Turkish baths are sometimes free from subsequent pruritus.

#CLASS VIII.--PARASITIC AFFECTIONS.#

#Tinea Favosa.#
(_Synonym:_ Favus.)

#What is tinea favosa?#

Tinea favosa, or favus, is a contagious vegetable-parasitic disease of
the skin, characterized by pin-head to pea-sized, friable, umbilicated,
cup-shaped yellow crusts, each usually perforated by a hair.

#Upon what parts and at what age is favus observed?#

It is usually met with upon the scalp, but it may occur upon any part of
the integument. Occasionally the nails are invaded. It is seen at all
ages, but is much more common in children.

#Describe the symptoms of favus of the scalp.#

The disease begins as a superficial inflammation or hyperaemic spot, more
or less circumscribed, slightly scaly, and which is soon followed by the
formation of yellowish points about the hair follicles, surrounding the
hair shaft. These yellowish points or crusts increase in size, become
usually as large as small peas, are cup-shaped, with the convex side
pressing down upon the papillary layer, and the concave side raised
several lines above the level of the skin; they are umbilicated,
friable, sulphur-colored, and usually each cup or disc is perforated by
a hair. Upon removal or detachment, the underlying surface is found to
be somewhat excavated, reddened, atrophied and sometimes suppurating. As
the disease progresses the crusting becomes more or less confluent,
forming irregular masses of thick, yellowish, mortar-like crusts or
accumulations, having a peculiar, characteristic odor--that of mice, or
stale, damp straw. The hairs are involved early in the disease, become
brittle, lustreless, break off and fall out. In some instances,
especially near the border of the crusts, are seen pustules or
suppurating points. _Atrophy_ and more or less actual _scarring_ are
sooner or later noted.

Itching, variable as to degree, is usually present.

#What is the course of favus of the scalp?#

Persistent and slowly progressive.

[Illustration: Fig. 66.
Achorion Schoenleinii X 450. (_After Duhring._) Showing simple mycelium,
in various st