XXVI.] THE EYE. 265 



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

 clear vitreous humour which occupies the 

 posterior cavity of the eye. 



8. Tilt the eye so that the cornea is underneath ; 

 through the vitreous humour can be seen the 

 choroid coat becoming folded longitudinally as it 

 approaches the lens, and so forming the ciliary 

 processes. 



The nervous elements of the retina cease at the 

 level of the commencement of the ciliary process. 

 Their termination 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 the retina as far as that line, but 

 in the region beyond its thin outer coat, the 

 hyaloid membrane, becomes attached to the 

 ciliary processes. If an attempt be made to 

 separate them here with the handle of a scalpel, 

 it will be found that the pars ciliaris retinas (or 

 the non-nervous continuation of the inner coat 

 of the retina) together with some of the pigment 

 layer of the retina (the outer coat) will come 

 away with the vitreous humour. 



At the ora serrata the hyaloid membrane be- 

 comes united to the membrana limitans interna 

 of the retina. 



10. Turn the eye with the cornea uppermost, and 

 cut away the free edge of the iris; make two 



