1100 



THE ORGANS OF SPECIAL SENSE 



is variously colored in different individuals, and is marked by lines which converge 

 toward the pupil. The posterior surface (fades posterior) (Figs. 805 and 820) 

 is of a deep purple tint, from being covered by two layers i of :j)igmented, columnar 

 epithelium, which layers are continuous posteriorly with the pars ciliaris retinae. 

 This pigmented epithelium is termed the pars iridica retinae, though it is sometimes 

 named uvea, from its resemblance in color to a ripe grape. 



CILIARY GANGLIATEO 

 PLEXUS 



CILIARY MARGIN 

 OF IRIS 



ATTACHED 

 REMNANT OF 

 CORNEAL 

 MARGIN 



CILIARY ZONE 

 OF IRIS 



PUPILLARY ZONE 

 OF IRIS 



PUPILLARY 



MARGIN 



CONTRACTING 

 FOLDS OF IRIS 



VASCULAR 

 EMINENCES 



LARGE 

 PIGMENT-CELL 



FREE BORDER 

 OF PIGMENTARY 

 LAYER 



FIG. 807. Section of the iris. Anterior surface magnified. (Toldt.) 



Structure. The iris is composed of the following structures: 



1. In front is a layer of flattened endothelial cells placed on a delicate hyaline basement 

 membrane. This layer is continuous with the endothelial layer covering the membrane of 

 Descemet, and in men with dark-colored irides the cells contain pigment granules. 



CILIARY 

 MUSCLE 



CILIARY 



GANGLIATED 



PLEXUS 



POSTER 

 LONG CILIARY 

 ARTERY 



NTERIOR RADICLES 

 F ONE OF THE 

 VORTICOSE VEINS 



^^^s^^s^m^^- 



FIG. 808. The ciliary gangliated plexus and the ciliary nerves entering the plexus. Outer surface of the 

 middle or vascular coat of the eyeball. (Toldt.) 



2. The stroma (stroma iridis) consists of fibres and cells. The former are made up of fine, deli- 

 cate bundles of fibroys tissue, of which some few fibres have a circular direction at the circum- 

 ference of the iris, but the chief mass consists of fibres radiating toward the pupil. They form, 

 by their interlacement, delicate meshes, in which the vessels and nerves are contained. Inter- 

 spersed between the bundles of connective tissue are numerous stellate cells with fine processes. 



