Colour Vision of the Fovea Centralis

Abstract

I HAVE read with great interest the letters of Drs. Stiles, Thomson and Pirenne in Nature of February 10, in which among other things König's early work is mentioned. Some experiments to be described below indicate, I think, that the factors involved are more complicated than has previously been supposed. Mr. Willmer is under the impression that it is only the fovea centralis that suffers from some form of dichromatism. I find, on the contrary, that it is a considerable area of the retina which is affected at times by this defect; all that has to be done to make the greater part of the retina appear dichromatic is sufficiently to reduce the visual angle of the test object.