377 



FIG. 30. THE RETINA IN VERTICAL SECTION 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, Collect- 

 ing cells on the front of the retina ; a a a, their axons which conduct impulses to the brain ; 

 6, an efferent fibre from the brain. 



