The scientific study of sympathetic ophthalmia began with the masterly description of William Mackenzie, in 1835. The second notable event in its history occurred in 1851, with the advocacy, by Augustin Pichard, of the excision of the injured eye as a means of preventing an outbreak of inflammation in the fellow eye. A tremendous stride was the demonstration, by Ernst Fuchs, in 1905, from a painstaking study of anatomic preparations, that sympathetic ophthalmia is a disease entity, distinct from any other malady of the organs of vision. The revelations of Fuchs gave great momentum to the problem of discovering the exciting cause. As the disease was always associated with openings in the eyeball, it was taken for granted that it was of an infectious nature, caused by some micro-organism introduced from without at the place of injury. The histologic observations of Fuchs strengthened this view. It was natural to