but often severe pains in the back and joints. His character changes; he becomes irritable, and at the same time stupid and morose.
At first the tongue is coated; later it loses its epithelium, the denudation extending not infrequently to the palate and gullet, and giving rise to a sore condition, often accompanied by a saltish taste and copious salivation. The gums may be swollen and bleed easily, a condition which gave rise to the name "Alpine scurvy." There may be eructations of gas, nausea, and vomiting. The appetite is variable. The epigastric region, and sometimes the lower part of the abdomen, are tense and painful. Constipation may be present, but in many instances there is diarrhœa of pale fermenting stools resembling those of sprue, and the stools may contain blood.
Fig. 73.—Simulium nigrogilvum, imago.
(Drawn by W. McDonald.)
From the commencement an erythema, not unlike a severe sunburn, is observable on those parts of the body which are, as a rule, unclothed and exposed to the sun. The eruption is symmetrical and characteristic. (See Frontispiece.) It appears suddenly, first on the back of the hands and feet, then on the forearms, legs, chest, neck, face, and, it may be, on the perineum, or on the female genitalia. The patches of erythema are irregular in outline and intensity. The affected area is swollen and tense, and the seat of burning or itching sensations which become particularly acute on exposure to the sun. The congestion disappears completely, but temporarily, on pressure. Petechiæ are common on the affected parts, and blebs may form with clear, opaque, or blood-stained contents of feebly
