THE EYE. 



2 mm. behind the margin of the cornea ; they divide into branches which supply 

 the ciliary processes, and join the circulus major. 



Fig. 42. PUPILLARY MEMBRANE OF NKW-BORN KITTEN, 

 INJECTED. (Kiilliker, from a preparation Ly 

 Thiersch.) Magnified. 



Besides these special arteries, numerous 

 minute vessels enter the iris from the ciliary 

 processes. 



The veins of the iris follow closely the 

 arrangement of the arteries just described. 

 The canal of Schlemm communicates with 

 this system of vessels. 



Pupillary membrane. In the foetus the 

 pupil is closed by a thin transparent vascular mem- 

 brane, the vessels in which are continued from 

 those of the iris and of the capsule of the lens 

 (which is also vascular in the foetus). Near the 

 middle of the pupil the vessels of the membrane loop round, leaving- the centre free from 

 vessels. They disappear in the seventh or eighth month of fcetal life, becoming 1 obliterated 

 from the centre towards the circumference, and the membrane itself is gradually absorbed in 

 like manner. A few shreds may still remain at birth : sometimes the whole membrane persists. 



Nerves of the choroid and iris. The ciliary nerves (fig. 43), about fifteen 

 in number, and derived from the ciliary ganglion and the nasal branch of the 



.--Anterior ehcwnber 



It-is 



Fig. 43. DIAGRAM SHOWING THE PRINCIPAL NERVES AND BLOOD-VESSELS OF THE EYEBALL. (Testut. ) 



ophthalmic division of the fifth nerve, pierce the sclerotic near the entrance of the 

 optic nerve, and come immediately into contact with the choroid. They are some- 



