SKIM'POLE, HAROLD. An amateur artist in Dickens's Bleak House, plausible but selfish, who lived on his friends. He was supposed to be a portrait of Leigh Ihint, but Dickens emphatic ally denied any such intention.
SKIN (Icel. skina: connected with OHG. scin tan, seindan,((er. schinden, to flay ). Considered in its general physiological and histological relation, the skin is merely a part of the great mucous sys tem to which the nit membrane and ing glands also belong. and which consists of two essential elements, a basement tissue, composed of simple cutaneous membrane, and an epithelium. of nucleated particles resting on it, while be neath the basement. membrane are vessels, nerves, and connective tissue. (See EPITHELIUM and Al t.
cotss MEMBRANE.) In the skin the hard and thick epithelium is termed cuticle or epidermis, and the true skin below it is termed the derma, or corium or cutis rem, and is chiefly formed of modified and very dense connective (or areolar or cellular) tissue.
The external surface of the skin formed by the cuticle is marked by furrows of different kinds. Sonic (termed furrows of motion) occur trans versely in the neighborhood of joints, on the side of flexion; others correspond to the insertion of cutaneous muscles; while others. of quite an other kind, are seen in aged and emaciated per sons. and after the subsidence of any great dis tention of the integument ; and besides these coarse lines, most parts of the skin arc grooved with very minute furrows, which assume various courses in relation to one another. These minute furrows are most distinctly seen on the palmar aspect of the hand and fingers, and on the sole of the foot. The outer surface of the skin also presents innumerable pores for the discharge of the contents of the sudo•iparous and sebaceous follicles, or the sweat and fat glands; and the modifications of epidermis known as hair and nails occur on the same surface. The epidermis is composed of stratified epithelial cells united to each other by a cement substance. Its entire thickness varies from 0.08 to 0.12 of a micro millimeter. The outermost layer is known as the stratum, cornewm, and is composed of several strata of dry, horny scales, without nuclei. Be neath this lies the stratum lacidum, a thin. clear, transparent layer of horny cells with faint nuclei, and next beneath this lies the stratum granulo sum (or rete mucosum. or rete Malpighii), which overlies and dips into the spaces between the papilla of the corium. The Malpighian layer
is composed of many strata of nucleated cells, which are flattened in the superficial layers. hut polyhedral in the deep portion. The pigment of the skin is found in the rete alpighii.
The deep layer of the skin consists of connec tive tissue, in which both the white and yellow fibrous elements are considerably modified as to the proportions in which they occur, and un striped muscular fibre is present in no inconsid erable quantity in some parts of the skin. Where great extensibility, with elasticity, is required, the yellow (elastic) clement predominates; and where strength and resistance are specially re quired, as in the sole of the foot, the corium is chiefly composed of a dense interweaving of the white (inelastic) element. The thickness and strength of this layer differ greatly in different parts, according to the amount of resistance re quired against pressure. The skin i* thicker on the hinder surface of the body than in front, and on the outer than on the inner sides of the limbs. It is unusually thin over the flexures of the joints. it is partieularly delicate in the eyelids, and proportionately so in sonic other situations where great mobility is demanded. In regions which are most subject to external pressure, as the soles of the feet, it is firmly united by very dense lamince to the subcutaneous fascia ; and the intervals between these are provided with pellets of fat, forming a cushion, as an additional means of protection to the delicate organs it in closes and covers. It is on the external surface of the eutis that the tactile papilla', or true or gans of touch are developed. The corium is divided into the 'reticular' and 'papillary' portions, the latter being the reddish-gray external superficial layer which contains the upper portion of the hair follicles and cu taneous glands, and whose most important elements are these tactile papilla. They are most abundant and largest in the palm of the hand and the sole of the foot, while in'the back and in the outer sides of the limbs they are almost en tirely absent. They occur as small, semi-trans parent, flexible elevations, which are usually con ical or club-shaped in form; but in certain parts, as the palm of the hand, present numerous points in Which ease they are termed compound papil he). In one square line of the palm of the hand, it has been calculated that there are SI com pound and from 150 to 200 smaller papilla:, ar ranged in tolerably regular rows.