Diseases of the skin : a manual for practitioners and students / by W. Allan Jamieson.

  • William Allan Jamieson
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: Diseases of the skin : a manual for practitioners and students / by W. Allan Jamieson. Source: Wellcome Collection.

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    2d. The glands contained within it, which produce oil, per- spiration, and hair. 3d. The appendages which it bears, the hair and nails. We may think of the skin as a series of layers of actively growing cells, the mucous layers of the epidermis, which secrete or elaborate their horny covering, much as the snail does its shell. These cells are sustained on a felt-like arrangement of fibres, which supports them like a cushion, and supplies them in the most perfect manner with nutritive material, while at the same time the outer horny layer is lubricated with oil, is moistened and kept from putrefaction by a briny fluid—perspiration—and is saved from friction by a more or less abundant covering of hair or down. The outer layer, or epidermis, is divisible in favourable specimens, and in some localities at least, into four layers. Of these two belong to the horny, and two to the mucous or vegetative layer. The most external layer is essentially insensitive and protective. It consists of flattened cells which have become converted into keratine, and are, except on the very surface, intimately and closely united, and with difficulty separable. The most external of these cells are being gradually loosened, and are continually cast off. This shedding is nearly imperceptible in health, as indeed all the waste of the body is. It is this which makes up the greater part of the cloud of dust which flies off when a stocking is shaken after having been worn for a few clays. When this dust is examined, it is found to consist of dry plates of keratine, which contain no or the mere trace of a nucleus, and are granular or fatty. Beneath the true horny layer lies the band of Schron or Oehl's stratum lucidum, a thin, brightly refracting, and in- distinctly striated layer, which stains red with picro-carmine. Unna thinks that when the skin becomes suddenly heated, the narrow slit-like opening in this, through which the duct of the sweat gland passes, becomes suddenly occluded, no sweat can pass, and the surface remains dry. The same result, dryness of
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