Mr. F. H——, aged thirty, had an attack of brain fever at twenty-three, followed by attacks of severe pain in the head, recurring every few days, weeks or months. These attacks were accompanied with slight convulsive symptoms and delirium, the pain being of a most excruciating character, and lasting from a few hours to two or three days. The attacks were gradually increasing in severity, but without any impairment of the faculties of the mind. On a Saturday night, he was brought home with one of his worst attacks. When I first saw the patient on Sunday evening, I found him in a half-delirious, stupid condition, yet when roused up, giving satisfactory answers to questions, but immediately sinking into his former condition, and every one to five minutes starting suddenly up and, with staring eyes and distorted face, uttering piercing shrieks and screams, and calling to those around to shoot him, split open his head with a hatchet—anything to release him from his sufferings. These paroxysms would sometimes be followed by a convulsive action of the diaphragm and abdominal muscles, ending in his sinking into the same dull, stupid condition as before. In the interval of calm, the respiration was remarkably slow and feeble, with a slow irregular pulse of forty beats to the minute. These symptoms becoming gradually worse, he sank into a comatose condition early Tuesday morning, expiring at daylight, sixty hours after the commencement of the attack. The post-mortem revealed greatly enlarged Pacchionian glands, with extreme thinning of the skull over the same. The pia mater was considerably congested. Upon turning the brain back for removal from the base of the skull, there was a sudden gush of water from the ventricles, sufficient of which was secured to show that the quantity could not have been less than two ounces. Upon opening the lateral ventricles, these cavities were found unusually large from distension by the fluid, while the _septum lucidum_ and _fornix_ were found in a soft, pulpy condition, the former being completely broken down and detached from the corpus callosum above. The gray portions of the corpora striata were also softer and more easily broken up than was natural.