Kraepelin, delirium sometimes develops with sudden rise of temperature. Restlessness, talking in the sleep, volubility or dulness precede an unusually violent delirium, sometimes terminating in stupor and death. The basis of these conditions in all cases is the toxic infection causing the fever, changes in metabolism, circulatory disturbances and an involvement of various organs, particularly the brain. A rapid and considerable rise of temperature usually causes delirium in typhoid, smallpox and erysipelas while it has no such effect usually in tuberculosis. This disturbance is a direct result of the influence of the toxins on the cortex. Alcoholism constitutes another well-known and common cause. In seventy per cent of the cases the duration was less than one week and the delirium disappeared with the fall in temperature. Some cases terminate in infection delirium or they may precipitate genuine attacks of manic-depressive insanity, dementia praecox or general paresis. The so-called acute alteration of Nissl was a very common change found in the cortical cells at autopsy. This very generally involved the entire cortex. Kraepelin describes another characteristic alteration observed in cases of typhoid delirium. The Nissl bodies are clumped together in the periphery, and are deeply stained, the processes also being unusually dark. Some cells show a shrunken nucleus with swollen, lightly stained bodies. Around these neurones there are usually large accumulations of elongated glia cells. In the infection delirium, so called, the mental disturbance develops in a case where there is no hyperpyrexia or where at least there is no relation between the psychosis and the temperature. A restless excitement ushers in the attack. Pressure in the head, mental dulness, depressed or sometimes cheerful moods, uneasiness, disturbed sleep and anxious dreams are common symptoms. Later a disturbance of consciousness appears and a special type known as "initial delirium" may develop. This is a common occurrence in typhoid fever.