_After Duhring._) Showing mycelium in various
stages of development, groups of spores and free spores.]

#What is the pathology?#

The fungus, consisting of mycelium and spores, the latter showing a
marked tendency to aggregate, invades the superficial portion of the
epidermis.

#Is tinea versicolor readily diagnosticated?#

Yes; if the color, peculiar characters and distribution of the eruption
are kept in mind.

It is not to be confounded with vitiligo, chloasma, or the macular
syphiloderm. If in doubt, have recourse to the microscope.

#State the method of examination for fungus.#

The scrapings are taken from a patch, moistened with liquor potassae, and
examined with a power of three to five hundred diameters.

#State the prognosis of tinea versicolor.#

With proper management the disease is readily curable. Relapses are not
uncommon.

[Illustration: Fig. 74. Tinea versicolor.]

#What is the treatment of tinea versicolor?#

It consists in daily washing with soap and hot water (and in obstinate
cases with sapo viridis instead of the ordinary soap) and application
of a lotion of--sulphite or hyposulphite of sodium, a drachm to the
ounce; sulphurous acid, pure or diluted; carbolic acid, or resorcin,
ten to twenty grains to the ounce of water and alcohol; or corrosive
sublimate, one to three grains to the ounce of water. Sulphur and
ammoniated-mercury ointments are also serviceable. The following used
alone, simply as a soap, or in conjunction with a lotion, is often of
special value:--

[Rx] Sulphur, praecip., .................... [dram]iv
Saponis viridis, ..................... [dram]xii. M.

After the disease is apparently cured, an occasional remedial application
should be made for several months, in order to guard against the
possibility of a relapse.

#Erythrasma.#

#Describe erythrasma.#

Erythrasma is an extremely rare disease, due to the presence and growth
in the epidermic structures of the vegetable parasite--the _microsporon
minutissimum_. It is characterized by small and large, slightly
furfuraceous, reddish-yellow or reddish-brown patches, occurring usually
on warm and moist parts, such as the axillary, inguinal, anal and
genitocrural regions. It is slowly progressive and persistent, but is
without disturbing symptoms other than occasional slight itching.

[Illustration: Fig. 75.
Microsporon Minutissimum x 1000. (_After Ri