VETBBINAEY OPHTHALMOLOGY. 



85 



face of the cornea. On the back of the iris is a thicker 

 layer containing pigment, which is continuous witli 

 that of the ciliary body and choroid. Now, this layer 

 of pigment, the uvea, may be frequently seen as 

 small bodies on a pedicle or stem in the pupillary 

 aperture. Indeed, they may pass through and show 

 in the anterior chamber. Called soot-balls (corpora 

 nigra). More often seen at the upper (pupillary) border. 



In color they are brownish- 

 black. TJnstriped muscle fiber 

 is the predominating constituent 

 of the iris, contained in a stroma 

 of connective tissue, which also 

 contains theYessels,nerves, lymph 

 spaces and cells. Around the 

 pupil some certain fibers are ar- 

 ranged circularly. This is the 



sphincter pupillcB, and the dilator of the pupil is formed 

 of radiating fibers. The peculiar disposition orjuncture 

 of these two sets of fibers is that they join each 

 other near the pupil in curves, as I here depict. 

 The sphincter governed by the third pair, the dilator 

 by the sympathetic. The i ris has three different classes 

 of nerves sent to it from the ciliary ganglion, which 

 ganglion has three roots — sensitive, motor and sympa- 

 thetic. The twigs which •emanate from this ganglion 

 pass to the sclera, surrounding the optic nerve. These 

 are named the short ciliary. Tlae two long posterior 



Fig. 43. 



