NAILS are flattened, elastic, horny plates, which are placed as protective coverings on the dorsal surface oLtheterminal phalauges of Each nail con sists of a root, in- part concealed within a fold of the a body; or exposed part attached to the surface of the .kin; and a free anterior extremity called the edge. The shin below the mot and body of the nail is termed the ntairi.e, from its being the part from which the nail is produced. This is thick, and covered with vascular papilla:, and its color is seen through the transparent horny tissue. Near the root the papillae are smaller and less vascular; hence the portion of nail corresponding to this part is of a whiter color; from its form, this portion is termed the lunola. It is by the successive growth of new cells at the root and under the body of the nail that it advances forwards, and maintains a due thickness, whilst at the same time its growth in a proper direction is insured. The chemical composition of the nails is given in the article HORNY TISSUES, to which class of structures they belong. According to the observation of Beau, the ringer-nails grow at the rate of about two-fifths of a low in a week, while the toe-nails only grow with about one-fourth of that rapidity. When a nail has been
removed by violence, or has been thrown off in consequence of the formation of matter (pus) beneath it, a new nail is speedily formed, provided the matrix has not been seri ously injured.
There is a very common and troublesome affection popularly known as ingrowing nail. Its most usual seat is by the side of the great toe. It does not in reality arise from any alteration of the nail, but from the adjacent soft Parts being. constantly pressed by the use of tight shoes against its edge. These parts become swoilen and inflamed; suppura tion ensues, and an intensely sensitive ulcer is formed, in which the nail is embedded. Surgical advice should at once be resorted to in these eases, as there is no probability that the ulcer will heal spontaneously, especially if the patient continua to move about, and thus keep up irritation. In obstinate eases, it is not unfrequently necessary to remove a portion of the nail, an operation attended with much pain, although quickly performed.