THE EYE, 8l 



bcr of the eye between it and the front of 

 the lens, and filled with the aqueous hufnor. 

 ^ Also the brown and gold iris, projecting into 

 the anterior chamber, and overlapping the 

 margins of the lens ; it surrounds the circular 

 pupil. 



c. The crystalline lens may now be exposed on its 

 anterior aspect by fastening the eye, with its 

 anterior side upward, by pins to a layer of 

 wax in the bottom of a dish, covering it with 

 water, and then cutting away the iris. Next 

 remove the lens, and note its bi-convex form. 



d. After removing the lens, the vitreous humor 

 will be seen. 



e. Take away carefully the vitreous humor, and 

 observe the retina, with its delicate vessels, 

 behind it. Detach the retina from — 



/. The pigmented choroid outside it. 



g. As the retina is raised note the point where 



the optic nerve is attached to it. 

 h. Raise the choroid, and the inner surface of the 



sclerotic coat will come into view behind it. 



205. After twenty-four hours, proceed to break away 

 the remainder of the base of the skull, and also the 

 bodies of two or three of the anterior cervical verte- 

 brae ; take care of the various nerves attached to the 

 brain and spinal cord. As the bone below the inter- 

 orbital septum is removed, note above it a cartilaginous 

 rod {trabecula cranii, or naso-ethmoidal cartilage) which 

 passes forward, and between the nose-chambers ex- 

 pands into a vertically placed cartilaginous lamella, 

 the representative of the ethmoid. This may not have 

 4* 



