ages of development, and free spores.]

#What are the symptoms of favus when seated upon the general surface?#

The symptoms are essentially similar to those upon the scalp, modified
somewhat by the anatomical differences of the parts.

The _nails_, when affected, become yellowish, more or less thickened,
brittle and opaque (_tinea favosa unguium_, _onychomycosis favosa_).

#To what is favus due?#

Solely to the invasion of the cutaneous structures, especially the
epidermal portion, by the vegetable parasite, the _achorion
Schoenleinii_. It is contagious. It is a somewhat rare disease in the
native-born, being chiefly observed among the foreign poor. The nails
are rarely affected primarily.

It is also met with in the lower animals, from which it is doubtless not
infrequently communicated to man.

#What are the diagnostic features of favus?#

The yellow, and often cup-shaped, crusts, brittleness and loss of hair,
atrophy, and the history.

[Illustration: Fig. 67. Epilating Forceps.]

#How would you distinguish favus from eczema and ringworm?#

From eczema by the condition of the affected hair, the atrophic and
scar-like areas, the odor, and the history. From ringworm by the
crusting and the atrophy. In this latter disease there is usually but
slight scaliness, and rarely any scarring.

Finally, if necessary, a microscopic examination of the crusts may be
made.

#State the method of examination for fungus.#

A portion of the crust is moistened with liquor potassae and examined
with a power of three to five hundred diameters. The fungus, (achorion
Schoenleinii), consisting of mycelium and spores, is luxuriant and is
readily detected.

#State the prognosis of favus.#

Upon the scalp, favus is extremely chronic and rebellious to treatment,
and a cure in six to twelve months may be considered satisfactory; in
neglected cases permanent baldness, atrophy, and scarring sooner or
later result. Although favus of the scalp persists into adult life, it
becomes less active and, finally, as a rule, gradually disappears,
leaving behind scarred or atrophic bald areas.

Upon the general surface it usually responds readily to treatment,
excepting favus of the nails, which is always obstinate.

#How is favus of the scalp treated?#

Treatment is entirely local and consists in keeping the parts free from
crusts, in epilation and applications of a parasiticide.

The crusts are removed by oily applicatio