112 ELEMENTARY PHYSIOLOGY. XXII. 



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 retina? (or the non- 

 nervous continuation of the inner coat of the retina) to- 

 gether with some of the pigment layer of the retina (the 

 outer coat) will come away with the vitreous humour. 



10. Turn the eye with the cornea uppermost, and cut 

 away the free edge of the iris; make two incisions at 

 right angles to one another on the/surface of the lens, 

 it will be seen that the lens is covered by a membrane; 

 this is the anterior part of the lens capsule. Carefully 

 remove the lens, and trace out the limits of the lens 

 capsule, noting that it forms a complete investment for 

 the lens. 



11. Gently separate with the handle of a scalpel the 

 lens capsule from the front part of the ciliary processes, 

 and observe that a membrane, the suspensory liga- 

 ment or zone of Zinn, passes from the edge of the cap- 

 sule to the ciliary processes, of which it forms the inner- 

 most layer, dipping down into their depressions. 



12. Looking into the eye from the front, observe 

 The entrance of the optic nerve. 



The blood vessels radiating out from the entrance of 

 the optic nerve. 



The iridescence, mainly below the entrance of the 

 optic nerve; it is caused by the irregular reflection of 

 light from the wavy connective-tissue fibres of the 

 choroid. In this region (the tapetum) the hexagonal 

 cells of the retina have no pigment. 



