rom the
constantly moistened state of its surface, is called the mucous
membrane. At the various orifices of the body, the exterior skin is
continuous with the internal.

ANATOMY OF THE SKIN.

618. The SKIN, to the naked eye, appears composed of one membrane. But
examination has shown that it consists of two layers of membrane,
namely, the _Cu'ti-cle_, (scarf-skin,) and the _Cu'tis Ve'ra_, (true
skin.) These layers are widely different from each other in structure,
and perform very different offices in the animal economy.

619. The CUTICLE (sometimes called the _ep-i-derm'is_) is the external
layer of the skin. This membrane is thin and semi-transparent, and
resembles a thin shaving of soft, clear horn, and bears the same
relation to other parts of the skin that the rough bark of a tree does
to the liber, or living bark. The cuticle has no perceptible nerves or
blood-vessels; consequently, if it is cut or abraded, no pain will be
felt, and no fluid will ooze from it.

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617. What is the skin? Mention its different appearances in its
different conditions in the human frame. Is the interior of the body,
as well as the exterior, covered by a skin? What is the interior
membrane called? Why has it received this name? 618-636. _Give the
anatomy of the skin._ 618. What is said of the skin? What is said
relative to these layers of membrane? 619. Describe the cuticle. What
name is sometimes applied to the cuticle?

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_Experiment._ Pass a pin through the portion of the cuticle that
skirts the nails, or remove a thin shaving from the palm of the hand,
and no painful sensation will be experienced unless the pin or knife
penetrates deeper than the cuticle.

620. This membrane varies in thickness on different parts of the
body,--from the thin, delicate skin upon the internal flexions of the
joints, to the thickened covering of the soles of the feet. The
greater thickness of the cuticle of the palms of the hands and soles
of the feet, is manifestly the intentional work of the Creator; for it
is perceptible in infants, even at birth, before exercise can have had
any influence.

621. The CUTIS VERA (sometimes called the _co'ri-on_) is composed of
minute fibres, which are collected into small bundles or strands.
These are interwoven with each other so as to constitute a firm,
strong, and flexible web. In the superficial part of the true skin,
the web is so close as to hav