Aschaffenburg described two forms of initial delirium. The first is a restless condition of clouding with hallucinations and delusions. The second form, which may develop from the first, shows active mental excitement. Mild in its onset, a confusional delirious state soon develops with flight of ideas, hallucinations, delusions, and marked anxiety. An initial delirium of this type often occurs in smallpox. This assumes a particularly severe form with a tendency to suicide and violence, strongly resembling epileptic dream states. Seizures and epileptiform convulsions may occur. The delirium usually develops from the third to the fifth day of the disease and mental enfeeblement sometimes follows. The attack usually lasts from several days to a week. It may continue as a fever delirium. About forty or fifty per cent die. Nissl in one case found a marked congestion of the vessels of the cortex, with an increase in the number of leucocytes, and a widespread destruction of the neurones. The cell bodies were swollen and the chromatin lumps destroyed. Karyokinetic changes were noted in the glia cells. More or less similar delirious states occur in the course of intermittent malarial fevers. These usually take the form of a marked anxious excitement, often with stupor or a tendency to violence. The attacks begin suddenly, last only a few hours and end in sleep. Convulsions are frequently observed. These conditions occur in the quotidian or tertian types but rarely in the quartan. The delirium precedes a febrile disturbance or may take its place. It is apparently due to an accumulation of plasmodia in the cerebral vessels. In influenza, restlessness, confusion, anxious excitement or hallucinatory deliria may be associated with a low temperature. Polyneuritic manifestations have also been observed. The disturbance is undoubtedly caused by the influenza bacillus or the action of its toxins on the cortex. Abscesses are found in some instances. Deliria with phthisis are rare unless there is a tubercular meningitis. In the septic infections, conditions with marked clouding are often observed, and are to be attributed to embolism, metastases, etc. Muscular weakness, aphasia, perseveration and convulsions may be present in these cases. Infection delirium also occurs in chorea. This takes the form of a clouded dreamlike state with confusion of thought at times, hallucinations, delusions, and emotional excitement accompanied by characteristic choreiform movements. Apprehension, as a rule, is unimpaired, but attention is disturbed and the patients are forgetful and distractible. They do not have a clear grasp on their surroundings. Occasional hallucinations appear. The mood is anxious, excited, fearful or irritable, sometimes with outbursts of anger or threats of suicide. The choreiform attacks are aggravated and speech is affected. The reflexes are decreased and muscular weakness develops. The pupils are dilated and sleep is interfered with to a marked degree.