598 



THE EYE. 



The larger branches of the nerves are covered with a sheath of flat- 

 tened cells which, as before mentioned, are in connection with the cor- 

 puscles of the cornea. At the points of junction of the plexus, nuclei 

 are frequently seen, but these appear to belong to the ensheathing cells, 

 and not to be interpolated in the course of the fibres. 



THE CHOROID COAT. 



The choroid coat of the eye (tunica choroidea s. vascnlosa) is a dark 



brown membrane lying between the sclerotic and the retina. It reaches 



p.^ ,ii. forwards nearly to the 



cornea, where it ends 

 by a series of plaits 

 or folds named ciliary 

 processes, disposed in 

 a circle projecting in- 

 wards at the back of 

 the circumferential por- 

 tion of the iris. At the 

 liinder part, where the 

 tunic is thickest, the 

 optic nerve is trans- 

 mitted. The outer 

 surface is rough, and is 

 connected to the scler- 

 otic by loose connec- 

 tive tissue and by ves- 

 sels and nerves. The 

 inner surface, which 

 is smooth, is covered 

 by the hexagonal pig- 

 mented cells of the 

 retina (which were 

 formerly described as 

 belonging to the 

 choroid). 



The ciliarij processes, about seventy in number, are arranged radially 



Kg. 405. — Choroid Mejibrakb and Iris exposed by 



THE REMOVAL OF THE ScLEROTIC AND CORNEA (after 



Zinn). Twice the natural size. 



a, one of the segments of tlie sclerotic tliro'OTi back 

 ciliary muscle; c, ii-is ; c, one of the ciliary nerves 

 one of the vasa vorticosa or choroidal veins. 



Fi- 406. 



tion at its inner or axial end. 



Fig. 40G. — Ciliary Processes as seen from 



BEHIND. f 



1, posterior sixrface of the iris, -with the 

 sphincter muscle of the pupil ; 2, anterior 

 part of the choroid coat ; 3, one of the ciliary 

 processes, of which about seventy are re- 

 presented. 



together in form of a circle. They 

 consist of larger and smaller folds 

 or thickenings, without regular 

 alternation ; the small folds number 

 about one-third of the large. Each 

 of the larger folds, measuring about 

 ^^^th of an inch in length and -jV^h 

 in depth, forms a rounded projec- 

 which is free from the pigment which 



