The Cuticle is subject to several anomalies, but they are not accurately known; and their relations to diseases of the cutis require especially to be explained.

1. It is very often formed in excess; and then either its outer layers are thrown off in the form of bran, scales, larger coherent masses, etc.; or its elementary structures, accumulating upon and beside one another, produce very various secondary formations, such as callosities, corns, and crusts, flat, convex, or concave scutes, cylindrical or angular, tessellated growths, and others which resemble stalks and thorns. Anomalies of this kind may be limited to certain circumscribed spots, or may extend over the whole body.

On the other hand, the cuticle is sometimes remarkably thin and delicate, and, therefore, transparent, at spots where it has been recently cast off.

2. An unnatural aggregation of the elementary constituents of the cuticle, and a simultaneous excess of its growth, produce the anomalies in the form of the epidermal tunic which have been already mentioned. I shall refer to this again amongst the anomalies of its structure.

3. Anomalies in the color of the skin reside for the most part in the epidermis. Its cells contain a pigment, perceptible chiefly in the deeper layers, which varies in quantity, and may be yellow, brown, or black. Such varieties in its color constitute the distinctive peculiarities of certain individuals, and certain races, but sometimes they are acquired. In the latter case the change may be limited to particular spots, or may extend over the whole body; and it presents considerable interest from its involving not only marked alterations in the condition of the organ, and in its secretion, but also anomalies of internal organs which indicate a revolution of the entire vegetative system. Pigment accumulates and discolors the skin in a remarkable manner in congenital naevi.

Total absence of pigment is a congenital defect in cases of Albinois-mus, and an acquired in cases of Achroma or Vitiligo. The former may be general or partial; the latter is at first always partial, but may at last become general.

4. The epidermis deviates from its normal consistence in being sometimes more or less moist, but more commonly very dry and harsh. It is the latter condition that produces its tendency to break and peel off in the form of bran or scales, as it is observed to do in many substantive diseases of the skin, and in cases in which it is a symptomatic occurrence and the skin is destroyed, especially by cancer. In those cases, likewise in which epidermis has accumulated in a thick layer over a diseased spot of skin, its dry condition occasions cracks, fissures (chaps, rhagades), which not unfrequently extend through its entire thickness, and even into the cutis.

5. The mutual relations, as to position, which subsist naturally between the elementary structures of the epidermis, are frequently disturbed, not only in consequence of their simple accumulation, but also by a simultaneous excessive development of the papillae of the cutis, and by various other accidental circumstances. Such anomalous relations of structure may be reduced generally to the two forms of a more developed laminated arrangement, and an apparently fibrillated structure. This class includes the anomalies in the shape of the epidermal tunic already mentioned-

The callosity, - tyloma, - which consists of a simple accumulation of epidermis in the form of strata lying over one another:

The corn, - clavus, - a small circumscribed painful callus that projects like a wedge into the corium;

The crusts, and the convex, flat or hollowed (concave) scutes exhibit a laminated structure, though the granular accumulations of dried exudation and pus frequently render it indistinct: but the cylindrical and angular formations resembling pavement, stalks, and thorns, though they also consist of lamellae of epidermis, are fibrillated, and the horny excrescences have a similar structure. The cutis upon which they grow is always diseased, though not, indeed, to the same degree in all cases; but beneath such growths it is unusually succulent, loosened, vascular, and hypertro-phied, and is developed, especially at its superficial lamina, into mushroom-like, cuneiform, thready, villous or even cleft, papillae. It is evidently so in genuine ichthyosis, and very probably in the milder allied forms of pitiriasis, psoriasis, and lichen. The primary and the secondary changes in the tissue of the skin in lepra are alike unknown.

Horns - cornea cutanea - either grow upon a cutis, diseased in the way just described, or spring from its deeper part, out of a cyst, which is, in fact, a degenerate sebaceous follicle. They have been met with at various parts of the body, but their principal site is the hairy part of the head, and the forehead: they occur sometimes even on the prepuce and glans penis. Usually only one exists, but sometimes there are two or more. Their length is occasionally very considerable, even as great as several inches; and they may be as thick as a finger: some of them are straight, others are twisted or curved; most of them are single, a few are cloven; their broadest part is always the base, the shaft is cylindrical or obtuse-angledj and the free extremity is generally pointed. As to color, they are mostly dirty brownish or black. They have been several times observed to be repeatedly shed at regular intervals. And when thus shed, or when accidentally or designedly removed, they are reproduced, provided the spot of skin which they spring from - the matrix - be not destroyed. They are somewhat more frequent in the female than in the male sex, and are common to old age rather than to other periods of life.