346 MICROSCOPIC ANATOMY OF THE ORGANS. 



situated in the angle of the anterior chamber, between the 

 cornea and iris. The fibres pass over into Descemet's mem- 

 brane, which in this region shows a fibrillar structure. There 

 occur here also, on the one side, free connective-tissue bundles 

 from the substantia propria corriese, and on the other side 

 connective tissue and elastic fibres of the intermuscular tissue 

 of the ciliary muscle and processes from the iris stroma. These 

 fibres form a network whose strands are covered with flat epi- 

 thelium continuous with the corneal endothelium and the 

 epithelium of the anterior surface of the iris. Between the 

 strands of tissue there are free spaces, the so-called spaces of 

 Montana. 



(3) Tunica interna. 



The retina is the third and innermost coat of the eyeball, 

 and contains the terminations of the optic nerve fibres. It lines 

 the whole posterior part of the eye, and ends at the pupillary 

 border of the iris. We can distinguish it in three zones: 1. 

 The pars oplica retinas, which extends from the place of entrance 

 of the optic nerve, to the neighborhood of the ciliary body y 

 where it ends in a zig-zag line, the ora serrata ; 2. The pars 

 ciliaris retince, from the ora serrata to the ciliary border of the 

 iris ; and 3. The pars iridica retince, which extends from the 

 ciliary border to the pupillary border of the iris. 



1. The pars optica retinae (Figs. 263 and 265) is the only 

 part of the retina which is sensitive to light. It consists of 

 several layers, the elements of which have been studied by the 

 newer methods, such as the vital methylene-blue staining, and 

 the Golgi impregnation. Three main layers can be made out: 

 the outermost pigment layer, the middle layer (Gehirnschicht), 

 and the innermost neuro-epithelial layer. The middle layer 

 is made up of six, the neuro-epithelial layer of four sheaths, 

 so that the retina possesses altogether eleven layers : 



1. Pigment layer. 



2. Layer of rods and cones ; ^ 



3. Mernbrana lirnitans externa; [ 



4. Outer granular layer; ( Neuro-epithelial layer. 



5. Henle's fibre layer. 



