ANATOMY OF THE EYE. 



557 



and is familiarly known as the pupil. This pupil is merely an 

 opening in the iris, which allows the rays of light to pass into the 

 interior of the eyeball. 



FIG. 216. 



Pigmented epithelium lying 

 next to the choroid coat. 



Kods and cones with their ex- 

 tremities imbedded in the 

 epithelial cells. 



External nuclear layer. 

 External granular layer. 

 Internal nuclear layer. 



Internal granular layer. 



Layer of nerve cells. 



Nerve-fibre layer in which the 

 retinal vessels run next to 

 the vitreous humor. 

 Diagrammatic section of retina, showing the relation of the different layers 

 in the posterior part of the fundus (not the macula luted). (Schultze.) 



Besides supplying nutrition to the non-vascular central parts 

 of the eyeball, the choroid is useful in vision by preventing the 

 reflection of the light from the background of the eye in such a 



