the true skin
is thrown into a series of minute elevations called the papillae, upon
which the outer skin is moulded. These abound in blood-vessels,
lymphatics, and peculiar nerve-endings, which will be described in
connection with the organ of touch (sec. 314). The papillae are large
and numerous in sensitive places, as the palms of the hands, the soles of
the feet, and the fingers. They are arranged in parallel curved lines, and
form the elevated ridges seen on the surface of the outer skin (Fig. 103).

235. The Epidermis, or Cuticle. Above the true skin is the epidermis.
It is semi-transparent, and under the microscope resembles the scales of a
fish. It is this layer that is raised by a blister.

As the epidermis has neither blood-vessels, nerves, nor lymphatics,
it may be cut without bleeding or pain. Its outer surface is marked with
shallow grooves which correspond to the deep furrows between the papillae
of the true skin. The inner surface is applied directly to the papillary
layer of the true skin, and follows closely its inequalities. The outer
skin is made up of several layers of cells, which next to the true skin
are soft and active, but gradually become harder towards the surface,
where they are flattened and scale-like. The upper scales are continually
being rubbed off, and are replaced by deeper cells from beneath. There are
new cells continually being produced in the deeper layer, which push
upward the cells already existing, then gradually become dry, and are cast
off as fine, white dust. Rubbing with a coarse towel after a hot bath
removes countless numbers of these dead cells of the outer skin. During
and after an attack of scarlet fever the patient "peels," that is, sheds
an unusual amount of the seal; cells of the cuticle.

The deeper and more active layer of the epidermis, the _mucosum_, is made
up of cells some of which contain minute granules of pigment, or coloring
matter, that give color to the skin. The differences in the tint, as
brunette, fair, and blond, are due mainly to the amount of coloring matter
in these pigment cells. In the European this amount is generally small,
while in other peoples the color cells may be brown, yellow, or even
black. The pinkish tint of healthy skin, and the rosy-red after a bath are
due, not to the pigment cells, but to the pressure of capillaries in the
true skin, the color of the blood being seen through the semi-transparent
outer skin.

[Illustration: Fig