271
Pediculosis Capitis 272
Pediculosis Corporis 274
Pediculosis Pubis 275
Cysticercus Cellulosae 276
Filaria Medinensis 277
Ixodes 277
Leptus 277
[OE]strus 278
Pulex Penetrans 278
Cimex Lectularius 278
Culex 279
Pulex Irritans 279

TABLE showing Relative Frequency of the Various
Diseases of the Skin 280

DISEASES OF THE SKIN.

#ANATOMY OF THE SKIN.#

[Illustration: Fig. I.
Vertical section of the skin--Diagrammatic. (_After Heitsmann._)]

#The Epidermis.#

[Illustration: Fig. 2.
_c_, corneous (horny) layer; _g_, granular layer; _m_, mucous layer
(rete Malpighii).
The stratum lucidum is the layer just above the granular layer.
Nerve terminations--_n_, afferent nerve; _b_, terminal nerve bulbs;
_l_, cell of Langerhans. (_After Ranvier._)]

#The Blood-vessels.#

[Illustration: Fig. 3.
_C_, epidermis; _D_, corium; _P_, papillae; _S_, sweat-gland duct.
_v_, arterial and venous capillaries (superficial, or papillary plexus)
of the papillae. Deep plexus is partly shown at lower margin of the
diagram; _vs_--an intermediate plexus, an outgrowth from the deep
plexus, supplying sweat-glands, and giving a loop to hair papilla.
(_After Ranvier._)]

#The Nervous and Vascular Papillae.#

[Illustration: Fig. 4.
_a_, a vascular papilla; _b_, a nervous papilla; _c_, a blood-vessel;
_d_, a nerve fibre; _e_, a tactile corpuscle. (_After Biesiadecki._)]

#The Hair and Hair-Follicle.#

[Illustration: Fig. 5. _A_, shaft of the hair; _B_, root of the hair;
_C_, cuticle of the hair; _D_, medullary substance of the hair. _E_,
external layer of the hair-follicle; _F_, middle layer of the
hair-follicle; _G_, internal layer of the hair-follicle; _H_, papilla of
the hair; _I_, external root-sheath; _J_, outer layer of the internal
root-sheath; _K_, internal layer of the internal root-sheath. (_After
Duhring._)]

#SYMPTOMATOLOGY.#

The