The patient, Mrs. X., aged about 55, came under my observation on the 27th of April, 1913, in consultation with my friend Dr. Hardin of Washington. At thirteen the patient had had scarlet fever, and six months later diphtheria, followed by more or less extensive paralysis. In other respects she had been a healthy woman and had had several children. For ten or twelve years, however, there had been some shortness of breath on exertion, and for eight months, frequent bleeding from the nose. For two months she had had peculiar periods of dizziness in which it had been noticed that her pulse was slow and irregular. Two weeks before she had had a sudden attack characterized by loss of consciousness and repeated slight convulsive seizures. Immediately after the attack the pulse was very slow, about 18 to the minute, and fairly regular. On the morning preceding the attack it