The subject of the following record was a married man, aged 40, whose business had brought in an income of about £2,000 per annum. The onset of his illness dated from an accident which was said to have occurred about seven months before he was seen by us. According to the history obtained from the wife it appeared that as he was passing a building in course of erection a fairly large piece of iron fell from the scaffolding and struck him on the left side of the head. He did not fall, but picked up the piece of iron, walked into the building and interviewed the foreman. He then went home, his only complaint being of headache. The wife said she noticed a swelling on the scalp, but as there was no bleeding or wound she did not send for a doctor immediately. The patient was put to bed and is said to have been sick on two occasions. As he did not improve, he was taken, after six days, to the out-patients’ department of a general hospital, where the doctor who saw him attributed the condition to concussion. He was admitted four days later and remained for three weeks. The report from the hospital stated that the patient complained of headaches, became easily irritable and lost all power of control. He is said to have been sleepless, but no sickness had occurred. There was no mention of any external damage to the head, and X-ray examination of the skull revealed no injury. The blood Wassermann reaction was negative and the blood precipitation test was normal. No physical signs of disease were discovered. The wife stated that while in this hospital the patient chased one of the doctors down the stairs. Soon afterwards he ran away from the hospital, telephoned to his wife and was taken back by her, remaining a further week. He then returned home, and after a few days’ rest resumed work. He was unable to continue as he became excitable and irritable, and on one occasion “smashed his office up”. He was seen by his own doctor, who expressed the opinion that the accident had undoubtedly caused a hæmorrhage inside the skull, and that the clot so formed was responsible for the patient's mental disability. Ten days later he was examined by a distinguished neurologist, who also expressed the opinion that a blood tumour from bleeding within the membranes of the brain was the cause of the symptoms. The patient gradually lost interest in his work, stayed at home and spent most of the day in bed, preferring to be left alone. He became violent and on more than one occasion attacked his wife.