CLASS VIII.--PARASITIC AFFECTIONS 247 Tinea Favosa 247 Tinea Trichophytina 251 Tinea Imbricata 261 Tinea Versicolor 262 Erythrasma 265 Actinomycosis 266 Blastomycetic Dermatitis 266 Scabies 267 Pediculosis 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.#