, is an affection
which attacks Europeans in hot climates. It is characterized by the
appearance of numerous red pimples of an irregular form, distributed
over those portions of the body usually covered by the clothing. It is
attended with a fierce, burning, itching sensation, which is aggravated
by warm drinks, friction of the clothing, and the heat of the bed. The
eruption indicates a healthy condition of the system; its suppression or
retrocession is an unfavorable symptom, denoting some internal affection
such as deranged nutrition.

[Illustration: Plate II.
Fig. 6. Fig. 7.
Fig. 8. Fig. 9.
Fig. 10. Fig. 11.
Fig. 12. Fig. 13.]

In _lichen planus_, as the term indicates, the pimples are flattened.
There is no sensation of itching or formation of scabs. The pimples are
solitary and have an angular base, and the fresh pimples formed appear
on the spaces between the former eruptions. This affection usually
attacks some particular region, such as the abdomen, hips, or chest.
Instances are recorded in which it has appeared on the tongue and the
lining membrane of the mouth. Sometimes it appears in patches, but even
then, the margin of each pimple can be discerned.

_Lichen pilaris_ and _lividus_ are modifications of lichen simplex, the
former being so named to describe the location of the pimples, _i.e._,
surrounding the minute hairs which cover the body, especially the lower
limbs. The term _lichen lividus_ indicates the dark purplish hue caused
by a torpid circulation and the consequent change of arterial into
venous blood before leaving the pimples. _Lichen circinatus_ is a
modified form of _lichen circumspectus_. The pimples in the center of
the circular patch subside and a ring is formed which gradually
increases in size. When the rings become broken or extend in regular
forms, the affection is termed _lichen gyratus_.

CAUSES. Constitutional debility predisposes the system to this eruption.
The exciting causes are irritation of the skin, strumous diathesis,
dentition, and any violation of hygienic rules. Although lichen is not a
fatal disease, yet it tends to reduce the vitality of the system.

IMPETIGO. (_Crusted Tetter_ or _Scall_.) Impetigo is a term applied to
an inflammation of the skin, more severe and energetic in its character
than the preceding affection. We have found the predominating
characteristics of eczema and lichen to be the presence of exudation in
the former, and the absence of it in the la