In _herpes zoster_, or _shingles_, the clusters of vesicles encircle
one-half of the body, frequently at the waist; hence, it has received
the name of _zona_ or _girdle_. The vesicles often develop into bullae,
and sometimes ulcerate. In _herpes phlyctoenodes_, the vesicles are
small, round, and irregularly distributed over the face, neck, arms, and
breast. This form is accompanied by febrile symptoms and offensive
excretions.

In _herpes circinatus_, or _ringworm_, the vesicles appear in circular
patches, or rings. This is the mildest form of herpes, and is not
attended by symptoms of constitutional disorder. The various forms of
herpes are represented in Colored Plate I, Fig. 3.

CAUSES. Herpes is not contagious. It is caused by vicissitudes of heat
and cold, violent emotions, excessive exertion, irritation of the skin,
and a general atony of the system.

MILIARIA is the name given to an eruption of vesicles which are larger
than those of eczema, but smaller than the bullae of herpes. At first,
the serum contained in the vesicles is perfectly transparent, and
reflects the red tint of the underlying skin, hence the name _miliaria
rubra._ But gradually it becomes milky and opalescent, hence, the term
_miliaria alba_. The vesicles of miliaria are generally solitary, and
appear on those portions of the body most liable to become heated and to
perspire. The eruption is preceded by chills, languor, slight fever,
intense thirst, a sharp prickling sensation of the skin, and profuse
perspiration. The vesicles soon desiccate and are replaced by a new
crop.

CAUSES. Miliaria is almost universally an accompaniment of febrile
disease, and all disorders in which there occurs a profuse perspiration.
The causes to which it may be traced in each instance are improper diet,
impure air, burdensome clothing, or strong emotions.

PEMPHIGUS is a peculiar eruption which appears upon the limbs and
abdomen. The affected part is of a bright red color, and, in a few
hours, small vesicles appear containing a transparent fluid. The
vesicles soon develop into bullae, entirely covering the inflamed
portion. The fluid becomes opaque and in a few hours escapes. The patch
is then covered with a yellow scab. Pemphigus may be either acute or
chronic. The acute form is subdivided according to the degree of
inflammation, as _pemphigus pompholyx_ in which it is severe, and
_pemphigus benignus,_ when it is mild. The bullae of pemphigus are
illustrated