Human Color Vision and Color Blindness

Abstract

The work of the past few years has begun to give us a reasonably complete account of receptor mechanisms in human vision. The human retina, like that of most other vertebrates, contains rods and cones. Human rods everywhere in the retina seem quite typical; but human cones present peculiar features. It has long been recognized that the outer segments of foveal cones are rod-shaped; they are attenuated cylinders about 50 microns long and about 1–2 microns wide.