Upon questioning a patient who has developed a pellagra eruption in the spring months there is often obtained a history of more or less prolonged neurasthenic manifestations during the preceding winter, chiefly dizziness, insomnia, apprehension, occipital heaviness and muscular fatigue. There may also have been previous sensitiveness of the mouth and slight epigastric discomfort. Along with the appearance of the eruption we may have more marked alimentary tract disorders consisting of stomatitis, gastric disturbances, especially pyrosis, with a recurring diarrhoea. Upon examining the eruption we note localized, sharply delimited, strikingly symmetrical skin lesions of those parts of the body which are chiefly exposed to the sun’s rays. This erythema is very similar to sunburn but often follows inadequate exposure to the sun and the erythema persists instead of fading. Desquamation continues for weeks or months instead of healing. The dry scaling area usually shows a striking pigmentation at the borders even after the central portions of the erythema have cleared up. The skin lesions instead of being dry and atrophic as is usual may more rarely be moist and oedematous. From a vague neurasthenia we have now more distinct neurological manifestations such as variations in the reflexes, tremors, especially of tongue, head and upper extremities and a depressed mental state with lack of mental concentration or lapses of memory. Later on we may have a toxic psychosis in which mutism is often noted in a mental state characteristically melancholic. [Illustration: FIG. 84.—Marked symmetry of all lesions. Illinois case. (From Lavinder and Babcock.)] A final cachexia, with dementia, loss of control of the vesical sphincter and a terminal diarrhoea, marks the end. Recurrences of clinical manifestations each spring, or possibly skipping a year, are striking features of the disease. While the skin and alimentary tract disturbances are usually in abeyance in the winter, this holds to less degree with the nervous symptoms. THE DIAGNOSTIC TRIAD We may then state that in a typical case we have the diagnostic triad or pellagrous symptom-complex of (1) symmetrical sharply delimited erythemas of certain portions of the skin surface exposed to the sun with (2) alimentary tract disturbances of stomatitis, epigastric and substernal soreness and burning, with pyrosis and a recurring diarrhoea and (3) neurological manifestations in which a prodromal neurasthenia is followed by paraesthesias, in which burning sensations are prominent, at times leading to suicide by drowning, with alterations of deep reflexes, tremors and, in more advanced stages, a confusional insanity. Burning sensations are noted in mouth, gullet and stomach as well as of the skin. Then too a burning sensation may be complained of in the area formerly the seat of a pellagrous eruption. The palms of the hands and soles of the feet often give a burning sensation.