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THE SKIN. 147
Malpighian layer, and appears to fade away gradually as it approaches
the surface. In the normal condition it is never found in the corium.
The color of the skin will depend upon the quantity of this pigmentary
deposit, A'arying from white to black according to race, and differing in
shade in the same race, as is illustrated in the blonde and brunette.

Appendages of the Skin.
In man these are the hair, teeth, nails, and sebaceous glands. The
teeth will be described elsewhere in this work.
The Hair, like the nails and the enamel of the teeth, is a peculiar
modification of the epidermis. It is developed from the epiblastic or
ujjper layer of the blastoderm, and consists necessarily of the same struc-
ture, and is governed by the same general laws of development, growth,
and sustenance, as the epidermis. It is found on nearly every part of
the surface of the body, the exceptional parts being the soles of the feet,
the palms of the hands, the eyelids, the inner surface of the prepuce,
glans penis, and the last phalanges of the fingers and toes.
Its color, length, and thickness vary according to the part of the
body on which it is found, and are influenced by race and tempera-
ment. The color, like that of the skin, depends upon the quantity of
pigment deposited within its structure, absolutely white hair having
none. Oftentimes the color varies, not alone in different individuals,
but in the same person, as the hair of the face
Fig. 74.
is seldom of the same shade as that on the
head.
The length of the hair varies from that
which does not extend beyond the opening of
the follicle to the longest grown upon the head.
Its thickness also varies considerably, that cov-
ering the head being finer than that found on
the face and on the borders of the eyelids, etc.
etc. Straight hair is coarser, and its trans-
verse sections are more circular, than curly
hair, which is generally fine and oval in trans-
verse section.
Anatomically, the hair is divided into a
root, shaft, and point.
The Follicle is formed by the dipping down
of the epiderm into the tissue below (Fig. 72).
The Root of the hair is that portion which
is in the hair-follicle of the skin. Section of Hair-follicle: 1, dermic
coat of follic'e; 2, epidermic coat
The Bulb is the expansion of the extremity or root-sheath ; n, outer layer of
dermic coat, with blood-vessels, ft,
of the root. h, cut across ; c, middle layer ; d,
inner or hyaline layer; e, outer
The Shaft is that portion of the hair above root -sheath; .7, "inner root-
/,
sheath ; h, cuticle of root-sheath ;
the mouth of the follicle. In straight hair its
/, hair.
transverse section is almost cylindrical ; in
curly hair it is compressed or oval. It is composed of compact tissue,
which gradually tapers as it approaches the end.
Histologically, the hair is also divided into three portions—the cuti-