THE EYE HI 



except at the junction of the sclerotic with the cornea, 

 and at the entrance of the optic nerve. In other places 

 there is only a loose connection, largely by means of 

 blood vessels. Remove a strip of the sclerotic, a few mm. 

 breadth, stretching from the optic nerve to the cornea. 

 Note its dark inner surface, or lamina f usca ; note also 

 in the front part of the choroid, close to the cornea 

 (region of the ciliary muscle), the pale fibres spreading 

 from the junction of the sclerotic and cornea, backwards 

 over the choroid. 



6. Carefully pinch up the choroid about half-way be- 

 tween the optic nerve and the cornea with a fine pair of 

 forceps, and snip it through. Underneath it will be seen 

 a thin membrane, the retina. The pigment layer of the 

 retina will probably be torn awaj^ with the choroid. 



7. Tear away a piece of the retina to expose the clear 

 vitreous humour which occupies the posterior cavity 

 of the eye. 



8. Extend the gap laterally and tilt the eye ; through 

 the vitreous humour will be seen the ciliary part of the 

 retina with the choroid coat becoming folded longitudi- 

 nally as it approaches the lens, and so forming the ciliary 

 processes. If they are not distinctly seen, cut away 

 more of the coats of the eye. 



The nervous elements of the retina cease at the level 

 of the commencement of the ciliary process. Their ter- 

 mination is marked by an uneven line, the ora serrata. 



9. Holding up the choroid and retina, cut them 

 through as far forward as the ora serrata; it will be 

 seen that the vitreous humour separates readily from 



