100 THE EYE AND EAR. 



the sclerotic^ taking care not to injure the deeper 2^ arts ; and 

 extend the cuts back towards the ojJtic nerve. Carefully peel off 

 the four flaps into which the sclerotic is now divided from the 

 underlying black choroid coat : turn them doivii, and pin them to 

 the dissectijig board so as to fix the eye with the iris upwards : note 

 the following points. 



i. The ciliary muscle is a whitish ring of unstriped 

 muscle connecting the outer margin of the iris 

 with the junction of the cornea and sclerotic. 



ii. The choroid is the dense black coat exposed by the 

 removal of the sclerotic. 



iii. The ciliary vessels pierce the sclerotic to convey 

 blood to and from the choroid, which is extremely 

 vascular. 

 iv. The ciliary nerves are seen passing through the 

 sclerotic to the choroid while the flaps are being 

 turned down. 

 \ . Make a couple of radial incisions^ about ^ inch apart, through 

 the iris and ciliary muscle, and turn back the portion of the iris 

 between the tivo cuts, so as to expose its hinder surface. 



i. The ciliary processes are a series of densely pig- 

 mented and close set radial folds on the hinder 

 surface of the outer margin of the iris ; they fit 

 into corresponding folds in the ligament which 

 surrounds and supports the lens. 



5. With a large pair of scissors cut the eye into tivo halves by a 

 horizontal incision at its equator. Turn over the anterior or outer 

 half, and examine it from behind : note the following parts. 



i. The ciliary processes. 



ii. The uvea is the layer of dense black pigment at 

 the back of the iris and ciliary processes. 



iii. The ora serrata is the indented anterior boundary 

 of the part of the retina sensitive to light: 

 in front of this the retina becomes extremely 

 thin, but really extends forwards as far as the 

 free edge of the iris. 



6. Turn the anterior half of the eye over, so that its outer or 

 corneal surface is uppermost : cut away the iris completely : note 

 the following points. 



