DISSECTION OF THE EYE. 91 



mammals. Each student should be provided with two 

 eyes, and care should be taken to have the eyes re- 

 moved from the pig before it is scalded by the butcher 

 for the purpose of removing the hair. 



No student should attempt to dissect the eyeball 

 before reading carefully in one of the human anato- 

 mies an account of its structure. The eye should be 

 dissected in a wide pan with a layer of bees-wax upon- 

 the bottom, and as much of the dissection as possible 

 should be done under water. 



Dissect off the muscles fat, etc., adhering to the eye- 

 ball, leaving only the optic nerve. In cleaning the eye- 

 ball notice the conpinctival membrane on the anterior 

 portion of the eyeball, and the ease with zuhich it can be 

 dissected off. Notice also that the optic nerve enters the 

 eyeball to the inside and not at the middle point. 

 ^ I. The Sclerotic Coat is the tough white connective- 

 tissue coat covering over the greater portion of the 

 eyeball. Anteriorly it passes suddenly into 



2. The Cornea, the transparent membrane covering 

 the front of the eyeball. Through it can be seen the 

 ins, with its circular opening, the/?^///. In the dead 

 eye the pupil is usually very much enlarged from the 

 dilatation of the iris. 



Fasten the eyeball to the bottom of the dissect ingfan 

 by passing a pin through the optic nerve. With a pair 

 of forceps pinch tip a piece of the sclerotic and cut 

 through it ivith the scissors. The sclerotic is rather 

 loosely attached to the underlying choroid coat, except 

 at the entj^ance of the optic nerve and near the cornea, 

 so that it can be cut throicgh without i^tjtiry to the 

 choroid. Starting from the hole thtcs made, dissect off 

 a wide strip of the sclerotic extending from the optic 

 7ierve to the cornea. 



