and soles, and more abundant on the ventral than the dorsal surface in man alone. A hair consists of a bulb lodged in a follicle, and a shaft projecting beyond the skin. The follicle is an inflection of the cuticle, and its cells become continued on the hair, being loaded with pigment if its hue is dark. The shaft consists of a soft pith, or medulla, and a cortex which forms of the entire thickness, and is composed of horny scales, inbricating or overlapping each other in a manner peculiar to each animal. The latter fact has been taken advantage of in medico-legal investigations to distinguish human hair from that of other animals. Its diameter varies from 0 to 1500, black hair and that of the beard being coarser than flaxen hair or that of the head. When they are cut short they again become pointed at the end, which is said to prove organization. Feathers, down,

Section of a Dark Hair, after Kölliker.

a. Medulla. b. Cortex with pigment spots. c. Inner layer of epidermis. d. Outer layer. e. Inner root-sheath, or Huxley's layer. f. Outer, or Henle's layer.

quills, and even horns, are modifications of this cuticular appendage. The medulla is soft, and apparently tubular in some animals; and in the seal, cat, &c., a nervous and vascular papilla is developed at the root. In other animals the erectores pilorum, or muscular slips which produce the state called cutis anserina in man,

are very distinct. The colours of hair-black, brown, red, or yellow-depend on the quantity of iron in the pigment, which is of an oily nature. It has been said

that fright or other emotions have decolorized hair in a few hours, but as no vessels permeate it, these statements are unaccountable. Hairs when rubbed become electrical, and are so sensitive to atmospheric changes as to be used as hygrometers. In the remarkable disease termed "Plica Polonica," hairs become matted together by a glutinous secretion, and are said to bleed when cut. It is said hairs grow after death, which opinion has originated from the projection of them, owing to the shrinking of the skin and tissues beneath it.

The Cutis is composed of white and yellow fibres, the former abounding where fixity is necessary, as in the sole of the foot; the latter predominating wherever elasticity is required, as near joints. Acetic acid dissolves the white, and thus displays the yellow arranged in diamond-shaped meshes; and tannin converts it into an insoluble matter, as in the

making of leather.

The contractility of the skin after death, if stimulated by galvanism, indicates the presence of muscular tissue, and this is most abundant in the scrotum and about the nipple. The cutis lies on a layer of areolar tissue, the superficial fascia. Lymphatics are so abundant in some places that their meshes are but a medicines applied endermically by blistering or inunc

wide;

tion are thus readily absorbed. The surface of the cutis is covered with nervous and vascular processes about Too

in length, the papillæ, and this layer is termed the corpus papillare. Their size and number vary in different parts of the body; in the hand they are arranged in curved rows to which the cuticle corresponds, there being often 40 rows in one square inch, and 60 pairs of papillæ in each row. A little artery enters each papilla, and is united to a vein by capillaries in loops. Nervetubes can be traced as far as the papillæ, in which they become indistinct-probably, by losing the white substance of Schwann, as in other special sense expansions. Wagner discovered" corpuscula tactus" in them, which are analogous probably to the Pacinian corpuscles.

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These latter bodies are found in the nervous pulp of the fingers and toes, especially if roughly used, and also in the mesentery of the cat, and other places where tactile sense does not seem to specially reside. As they measure they can be seen readily on the twigs of the digital nerves. nerve-tube passes up through the whole axis of the body, and having lost its white substance, is of a pale colour. It usually ends in a blunt extremity, but in some instances it passes on to another corpuscle on the same nervestalk, and then regains its outer coat as it leaves the first corpuscle. The rest of the body consists of concentric laminæ, often 60 in number, the outer being separated by fluid which escapes as each layer is punctured. From this A Pacinian Corpuscle, with the nerve-axis in arrangement their discoverer compared them to the electric organs of some fishes. That they are rather ganglionic than essentially appendages to the spinal system, would appear from the fact that they are enlarged in paralysed limbs, and Cruveilhier regards them as altogether abnormal.

the centre.

The Glands of Skin are, 1, sebaceous, which always accompany hairs, and are therefore absent in the palms and soles. They are largest and most numerous about the nose, arms, groin, and other flexures. They lie under or in the structure of the cutis, and 2 or 3 open into each hair follicle. They secrete an oily hydrocarbon, of which the system is thus ridded, and which serves to lubricate and render pliant the skin. Simon discovered the entozoon folliculorum in these glands. The Meibomian glands and the odoriferous glands, which Tyson discovered round the glans penis, are modified sebaceous glands. The latter are peculiar in not accompanying hairs; the smegma præputii which they produce contains many epithelial scales. The wax glands of the ear pour out a material somewhat analogous to sebaceous secretion, but in anatomical configuration they more resemble the sweat glands. 2. The sudoriferous glands lie deeper, usually set in the subcutaneous fat, the particles of which they much resemble-but they have a pinker tint. Each consists of a tube inflected from the cuticle which gives it its epithelial lining, the basement layer being derived from the true skin. It is spiral in the cutis except near the papillæ, and again spiral while it passes through the cuticle; and as it has no basement layer here, it may be regarded as merely a tubular passage in it. It opens in an oblique or valvelike orifice about ro in diameter. E. Wilson calculates there are 3528 perspiratory openings on the square inch of the palm, or 2800 on an average over the whole body. As the surface of a man of ordinary stature equals about 2500 square inches, and as each duct is about of an inch long, he concludes there are 28 miles of such tubing altogether.

The functions of the complex organ we have sketched are numerous, and may be divided into mechanical, sensitive, and excretory. 1. The skin affords a tough yet flexible and elastic covering to the whole surface-modi

fied in various places according to circumstances. The cuticle, like a varnish, retains moisture, and when it is removed from any part of the subject, this soon dries up; it also blunts the too high sensibility of the papillary surface. Its appendage, hair, tends to preserve a uniform temperature. The skin is not impermeable to moisture, as increase of weight takes place by immersion in a bath, and thirst has been thus relieved. It is probable that the hands and feet are the only place where absorption of water takes place, as all other parts are made water-proof by the sebaceous secretion. 2. The relative sensibility of different parts of the surface depends chiefly on the number of papillæ, and can be determined by Weber's method. He placed the points of a compass, slightly blunted, at various distances on the skin of a person blindfolded, and found, for instance, that they should be separated 3 inches on the back of the thigh before they were perceived as separate points of contact. On the tip of the tongue and the middle finger a separation of gave rise to two perceptions of touch. These results did not vary in one individual for 11 years. The difference depends much on the thickness of the cuticle, for there are not 50 times as many papillæ upon the tongue as upon the back. This method may be employed to ascertain the amount of anesthesia in many cases of disease. If the points be drawn from a sensitive surface to one less so, the person will think they converge, and vice versa. The other senses greatly aid touch, and if they are lost it becomes greatly exalted-thus, our noble countryman, Lord Rosse, informs us that the only efficient polisher of telescope specula in London, some years ago, was a blind man named Cuthbert. Saunderson, professor of mathematics at Cambridge, although blind, could distinguish spurious medals from genuine ones by touch, and Rudolphi records an instance where a blind man could distinguish different coloured cloths. These remarkable results were pro