

-Illl. I VI. AND IHI. SI-.NSK OF SIGHT 



80S 



bullock, is a circular curtain attached to the edge of the cornea 

 all round, leaving in the centre an aperture which appears 

 dark. The curtain is called the iris. The aperture is 

 called the pupil. The colour of the iris, black, brown, blue, 

 and the like, is due to the varying amount and distribution of 

 granules of black pigment in it. 



At the edge of the cornea the iris is continuous all round 

 with a second coat which lines the hinder three-fourths of the 



c 



Civ 



Fie. 95. Diagram of the eye. 



Scf, sclerotic, shaded, continuous with c, cornea, not shaded ; r.c, epithelium of 

 cornea, continuous with e.cj, epithelium of conjunctiva ; Ck, choroid ; C.P, ciliary 

 process; /, in*; K, retina; t'.K, pigmented epithelium between retina and 

 choroid ; the retina proper ends at the wavy line at, but is continued as a thin 

 layer, }*.R, over the ciliary processes; L, lens; */./, its suspensory ligament; 

 I'.H, vitreous humour ;/.c, yellow spot ; O.N, optic nerve. 



eye. This coat is called the choroid ; it is loosely attached 

 to the inner surface of the sclerotic up to the edge of the 

 cornea, where it leaves the outer coat and juts out across the 

 eye, forming the iris. The choroid is much thinner than the 

 sclerotic and is very richly supplied with blood-vessels. Its 

 inner surface is black because it is lined by a layer of cells full 



