Clinical history.—JM, a male aged 15 months, was admitted on October 30, 1947, to the London Hospital on. account of an increase in the size of his head, first noted at the age of 7 months. In the month before admission the circumference increased by 25 cm. and during this time the child had been fretful, slept poorly, screamed day and night and had been vomiting copiously. At the age of< S months it was first noticed that he was backward us he was neither sitting up nor attempting to do so. At the time of admission he still could not sit up or raise his head. The birth-weight was 241 kilos. He was delivered by Caesarian section at the eighth month because of placenta prasvia. On examination.—A fretful, backward child, who could not sit or raise its head. Physical development was less than normal for its age. The skull had a circumference of 50 cm., the frontal region being unduly prominent. The anterior fontanelle bulged even when the child was not crying. The central nervous system showed no abnormality. The plantar responses were extensor on both sides. The other systems were normal. A lumbar puncture seventeen days before death yielded approximately 1 cc of water-clear fluid. Cells were less than 5 per c. mm. Protein 30 mg. per 100 cc WR negative. Lange om oo.

Progress.—-On the day after admission the child developed a fever which continued without remission until death three weeks later. Re-examination after a few days showed no further signs except an increased respirator)'rate, tachycardia and fever, with doubtful signs at the right base. The child was more irritable. Chemotherapy with penicillin and sulphamethazine failed to influence the temperature. Eleven days before death a Jacksonian seizure occurred involving the right side, with twitching of the mouth and eye and movement of the arm and leg. This was followed by a period of coma lasting five minutes. Diarrhoea and vomiting began and became severe. A rectal swab yielded no pathogenic organisms. The child gradually became more dehydrated, the temperature rose still further and he became comatose. Death occurred in hyperpyrexia on November 19, 1947. Family history.—Both mother and father are alive and well. One sib died fifteen days after delivery, presumably following birth trauma in an extended breech presentation. The second child, a girl now aged 4 years 3 months, has never been seriously ill, is described as intelligent and observant, and is at present quite healthy.