Abstract
On May 29, 1933, E. M. Kroger, a white man, aged 48, came to the office because of a sudden attack of blindness in the right eye, which had occurred one hour before. The personal history and the family history were irrelevant, except that he had lived in the tropics for a number of years. He had never had any tropical diseases or any other sickness. There was no history of injury to the eye or of being struck in the eye by a fly. There had been no break in the skin or mucous membrane recently, except for a tick bite on the body two weeks previously. Examination of the eye showed a partially dilated pupil which was not responsive to direct light, but retained its power of consensual reaction. Ophthalmoscopic examination revealed a small black point in the center of the optic disk moving actively in a