A, after Exposure to Bright Light;
B, After Resting in the Dark.
The arrow shows the direction in which light traverses the retina.
C, Retinal epithelium, with its pigmented fringe. 1, Layer of rods and cones, separated by the external limiting membrane from 2, the layer of the nuclei of the rods and cones. 3, The ganglion-cells of the retina, which are homologous with the cells of the afferent root of a spinal nerve. Their peripheral axons ramify beneath the sensory epithelium (rods and cones and their nucleus-bearing segments), their central axons in 4, the inner molecular layer.
D, Collecting cells on the front of the retina; a a a, their axons which conduct impulses to the brain; b, an efferent fibre from the brain.