(_b_) Atrophy due to defective innervation sometimes affects the skin and bones. In the former, after nerve-injuries more especially, we observe loss of thickness, glossiness, and perverted circulation and secretion; the hairs may fall out or grow abnormally; the nails are slow of growth, thick, rugose, incurvated, and brittle. In other cases, as in cerebral and spinal paralyses, the skin of the paralyzed part is abnormally dry, rough, and furfuraceous, and it loses its elasticity. In some varieties of so-called skin diseases the patches of altered nutrition (eczema, bullæ, herpes, psoriasis, leucoderma, scleroderma, etc.) are often, probably, dependent upon nervous lesions. In the very rare disease known as progressive facial atrophy the skin, subcutaneous areolar tissue, and the bones undergo extreme atrophy. The initial lesion is usually a patch of scleroderma with or without neuralgic phenomena; the skin is thin, darker and smoother than normal; it soon adheres to the subjacent bone (maxilla or zygoma), which itself steadily diminishes in size. Almost the entire half of the face (including the palate and tongue) may ultimately show the atrophic changes. We are not yet prepared to state the causal nerve-lesion in this disease. The bones are abnormally fragile (fragilitas ossium) in some nervous diseases, more especially in dementia paralytica and posterior spinal sclerosis; but whether this condition is due directly to the nervous disease or is the expression of more general malnutrition is now undecided.