This is a very complete clinical report of a case of some interest. The patient, a man, æt. 68, with nothing special in his family history, had contracted syphilis at the age of 21; twenty years later, after a period of intense brain work, he had a sudden attack of localised frontal headache with paresis of the right side. The paralytic symptoms cleared up rapidly, but the patient remained subject to headache and vertiginous attacks, and also to periodic fits of morbid anger with impulsive violence to things and persons about him. Latterly, these symptoms increased, and the patient's mental power declined.