In 1935 we1 published a clinicoanatomic study of 5 cases of a neurologic disorder observed in monkeys, Macacus rhesus, in the Zoological Garden of Antwerp, Belgium. In 3 of these cases the termination was fatal, which permitted a complete histologic study of the lesions. We called this disorder "acute amaurotic epilepsy." The syndrome was characterized by awkwardness in movement, epileptiform seizures and disturbance of vision, unassociated with changes in the optic fundi. The duration of the illness was usually from five to eight days, but frequently was only thirty-six hours. It was not always fatal. There were no symptoms referable to dysfunction of the pyramidal system or the peripheral neurons; there was no anemia, digestive trouble or pulmonary complications. Both sexes may be affected, though in our series the females were more often attacked than the males. The cause of the disease is as yet undetermined. Attempts to transmit