76 DISSECTION OF THE CAT 



Divide the eye into an anterior and posterior half. 



3. The Vitreous Humor is the transparent, jelly- 

 like mass filling the posterior chamber of the eye, 

 which has now been exposed. 



4. The Retina is the innermost of the three 

 coats of the eye. It is a delicate membrane 

 formed by the expansion of the optic nerve on 

 the interior of the eye. The optic disc, or blind 

 spot, is the small, white,, round area at the point 

 where the optic nerve pierces the sclerotic and 

 choroid coats and expands into the retina. The 

 blood-vessels supplying the retina radiate from the 

 blind spot. 



5. The Choroid is the thin coat of the eye lying 

 between the sclerotic and the retina. It is of a 

 dark color, owing to the pigment which is every- 

 where present, except in a circular area on the 

 back of the choroid, around and above the en- 

 trance of the optic nerve. This spot is of a lighter 

 color, and is known as the tapetum. 



6. The Ciliary Processes are the irregular folds 

 into which the choroid is thrown at the margin of 

 the cornea. 



7. The Ora Serrata is the anterior toothed mar- 

 gin of the retina. It lies around the periphery of 

 the ciliary processes. 



8. The Crystalline Lens is a transparent, double 

 convex body, situated in front of the vitreous 

 humor. It is more convex anteriorly than poste- 



