e external
tibial nerve. 15, The muscular branch of the external peroneal nerve.
18, The muscular branch of the sciatic nerve. P, Q, The posterior
tibial nerve.

The letters and other figures indicate minor nervous filaments
distributed to the various muscles and the skin.

PLATE IX.

THE SKIN.

Fig. 1. _A perspiratory Tube and Gland._ 1, 1, The contorted portion
of the tube that forms the gland. 2, 2, Two branches which unite to
form the main duct of the gland. 3, 3, The perspiratory tube. 4, The
cuticle. 5. Its colored portion. 6, The cutis vera, (true skin.) 7, 7,
Fat vesicles, in which the gland is imbedded.

Fig. 2. _A Papilla of the Skin._ 1, 1, Two papillae, formed of an
artery vein, and nerve. 2, 2, 2, 2, Nerves forming a loop in the
papillae. 3, 3, Arteries of the papillae. 4, 4, Veins of the papillae. 5,
5, A net-work of arteries, veins, and nerves. 6, 6, Nerves of the
skin. 8, 8, Arteries of the skin. 7, 7, Veins of the skin.

Fig. 3. _A Hair, and its Oil-Glands._ 1, 1, The hair. 2, 2, The sheath
of the hair. 3, Oil-glands that surround the bulb of the hair, the
ducts of which open into the sheath of the hair, (2, 2.)

Fig. 4. _A Section of the Skin._ 1, 1, The cuticle. 2, 2, Its colored
portion. 3, 3, The papillary layer. 4, 4, A net-work of arteries,
veins, and nerves, upon the upper surface of the cutis vera. 5, 5, 5,
5, The cutis vera, (true skin.) 6, 6, 6, Hairs that originate in the
cutis vera. 7, 7, 7, Oil-glands, the ducts of which connect with the
sheath of the hair. 8, 8, 8, 8, 8, 8, 8, 8, Perspiratory glands and
their ducts. 9, 9, 9, 9, 9, Nerves of the skin 10, 10, 10, 10, 10,
Arteries of the skin. 11, 11, 11, 11, 11, Veins of the skin. 12, 12,
12, 12, Papillae, or ridges of the skin.

PLATE X.

AN ANTERO-POSTERIOR SECTION OF THE EYE.

Fig. 1. 1, 1, The sclerotic coat. 2, 2, The cornea. 3, 3, The choroid
coat. 4, 4, The retina. 5, 5, The iris. 6, 6, The posterior chamber of
the eye that contains the aqueous humor. 7, 7, The anterior chamber.
8, 8, The pupil. 9, The crystalline humor. 10, 10, The vitreous humor
11, The optic nerve. 12, A representation of a pen. 13, An inverted
image of the pen (12) on the retina. 14, 14, A canal surrounding the
crystalline humor. 15, 15, The bevelled junction of the cornea and
sclerotic coats. A, a perpendicular ray of light from the pen. B, B,
oblique rays, that are refracted in passing through the humors of the
eye.

Fig. 2. _A View of the Ex