420 CILIARY LIGAMENT. 



the iris ; and appears generally of a gray color ; but contains the 

 ciliary nerves and arteries, in great numbers, as they pass to the iris. 



In this circular band is a small canal, discovered by the 

 Abbe Fontana, as mentioned p. 414 ; its use is to lodge a 

 small venous sinus.* 



All the choroides, which is posterior to the ciliary ligament, 

 is in close contact with the internal surface of the sclerotica ; 

 but the choroides continues anterior to the ligament ; and this 

 anterior portion takes a different position. It no longer lines 

 the internal surface of the shell of the eye ; but is reflected 

 inwards ; and takes a transverse direction, as if it were to 

 form a partition. This reflected part forms the ciliary body, 

 and the ciliary processes, which will soon be described. 



The choroides begins to take this reflection inwards, at the 

 place where it is connected with the ciliary ligament. Imme- 

 diately anterior to the ligament, the cornea is continued from 

 the sclerotica, and, being more convex than the sclerotica, it 

 projects externally and anteriorly. As the ciliary ligament is 

 situated between the sclerotica and choroides, very near to the 

 place where the sclerotica unites to the cornea, and where the 

 choroides is reflected internally to form the ciliary processes, 

 the edge of the ciliary ligament must lie in the angle formed 

 by the cornea, which is anterior and external, and the reflec- 

 tion of the choroides, which is internal. To this edge of the 

 ciliary ligament is fixed the circumference of the circular 

 membrane, called Iris, which is now to be described. 



The Iris 



Is a flat membrane, which does not partake of the spherical 

 figure of the sclerotica and cornea, or of the choroides, but 

 extends across a portion of the cavity of the eye, and forms a 

 septum. As it is circumscribed by the ciliary ligament, it is 

 necessarily circular. It has a round foramen near its centre, 

 which is called the Pupil, which, in the healthy subject, varies 



* See Fontana on the Poison of the Viper, vol. 2, page 310 ; and also Adolph 

 Murray, Nova Acta Upsal, vol. 3. 





