The Cones of the Grass Snake's Eye

Abstract

IN the course of an investigation of the photosensitive pigments of the grass snake retina, photomicrographs were taken of fresh flat retinal preparations. The retina was carefully removed from a newly killed animal and mounted in a drop of saline confined within a shallow wax ring on a coverglass with the outer retinal surface in contact with the glass. The whole was then inverted on to a slide¹ and examined under the microscope. In such a preparation the light passes across the retina in the same direction as it does in the living eye, that is, from the internal to the external limiting membrane, and then along the visual cells parallel to their long axes. What one looks at down the microscope is a cross-section of the visual cells.