318 ANATOMY OF THE RABBIT 



(c) The retina, the innermost layer of the eye, forms a thin 

 soft membrane covering the inner surface of the chorioidea. 

 It is divisible into a larger optic portion, the sensory part 

 of the eye, and a smaller ciliary portion, lying about the 

 periphery of the lens and distinguishable by the radiate 

 markings of its surface, the latter formed by the projecting 

 ridges of the ciliary body, the inner surface of which it 

 covers. 



A little distance from the centre of the optic portion 

 can be recognized the disc or "blind spot", where the nerve 

 fibres in the retina converge and form the optic nerve. 



(d) The transparent lens of the eye is suspended by fine fila- 

 ments, the zonular fibres, reflected from the margin of the 

 ciliary body. 



When the eye is at rest, the zonular fibres are in a state of tension 

 sufficient to produce a slight flattening of the lens. Contraction of the 

 muscles in the ciliary body reduces this tension so that the lens may 

 become more convex by its own elasticity. 



(e) The vitreous body (corpus vitreum), a transparent mass, 

 of gelatinous consistence, occupies the large space enclosed 

 by the lens and the retina. 



(/) The space enclosed between the surface of the lens and the 

 cornea is divisible into a large portion, the anterior chamber 

 (camera oculi anterior), lying outside of the iris, and a 

 smaller portion, the posterior chamber (camera oculi 

 posterior), lying between the iris and the lens. These two 

 chambers communicate through the central aperture en- 

 closed by the free margin of the iris, the pupil (pupilla). 



12. Following the removal of the eye, the blood-vessels and nerves 

 of the orbit may be freed from the remaining portions of the 

 eye muscles and examined. In order to see their connections 

 in the anterior angle of the orbit, it is necessary to break away 

 the anterior root of the zygomatic arch, and also the bony ridge 

 which lodges the alveoli of the posterior cheek-teeth. 



(a) The internal maxillary artery enters the orbit through the 

 anterior sphenoidal foramen in the root of the lateral 

 lamina of the pterygoid process. At the posterior ventral 



