bstance, and overlapping each other, like slates on a roof, in a
direction toward the free end.

The sebaceous glands are branching tubes ending in follicles or sacs and
opening into the hair follicles, lined by a very vascular fibrous
network representing the dermis, and an internal layer of cells
representing the mucous layer of the cuticle. The oily secretion gives
gloss to the hair and prevents its becoming dry and brittle, and keeps
the skin soft and supple, protecting it at once against undue exhalation
of water and undue absorption when immersed in that medium. Besides
those connected with the hair follicles there are numerous, isolated,
sebaceous glands, opening directly on the surface of the skin, producing
a somewhat thicker and more odorous secretion. They are found in large
numbers in the folds of the skin, where chafing would be liable if the
surface were dry, as on the sheath, scrotum, mammary glands, and inner
side of the thigh, around the anus and vulva, in the hollow of the heel,
beneath the fine horn of the frog, on the inner side of the elbow, on
the lips, nostrils, and eyelids. When closed by dried secretion or
otherwise these glands may become distended so as to form various-sized
swellings on the skin, and when inflamed they may throw out offensive,
liquid discharges, as in "grease," or produce red, tender fungous
growths ("grapes.")

The sweat glands of the horse, like those of man, are composed of simple
tubes, which extend down through the cuticle and dermis in a spiral
manner, and are coiled into balls in the deeper layer of the true skin.
In addition to their importance in throwing offensive waste products out
of the system, these glands tend to cool the skin and the entire economy
of the animal through the evaporation of their watery secretion. Their
activity is therefore a matter of no small moment, as besides regulating
the animal heat and excreting impurities, they influence largely the
internal organs through the intimate sympathy maintained between them
and the skin.

Diseases of the skin may be conveniently divided, according to their
most marked features, into--

(1) Those in which congestion and inflammation are the most marked
features, varying according to the grade or form into (a) congestion
with simple redness, dryness, and heat, but no eruption (erythema);
(b) inflammation with red-pointed elevations, but no blisters
(papules); (c) inflammation with fine, conical elevations,