1110 



THE ORGANS OF SPECfAL SENSE 



come into apposition with the septa. The fibres run in a curved manner from the septa on the 

 anterior surface to those on the posterior surface. No fibres pass from pole to pole, but they 

 are arranged in such a way that fibres which commence near the pole on the one aspect of the 

 lens terminate near the peripheral extremity of the plane on the other, and vice versa. Each 

 .fibre of the outer layers of the lens contains a nucleus, and these nuclei form a layer, the nuclear 

 layer, on the surface of the lens. The nuclear layer is most distinct toward the circumference 

 of the lens. The anterior surface of the lens is covered by a single layer of transparent, columnar, 

 nucleated epithelial cells (epithelium lentis). At the equator these cells become elongated and 

 their gradual transition into lens fibres can be traced. 



INSERTION OF 

 TENDON OF SUPERIOR. 

 RECTUS MUSCLE 



SCLERA ; 



ARS OPTICA 

 RETIN/E 

 ORA SERRATA 

 PARS CILIARIS RETIN/E 



ANTERIOR CILIARY 



ARTERIES AND 



VEINS 



CIRCULAR 

 MAJOR 



PIGMENTARY LAYER 

 OF RETINA 



CHOROID 

 PERICHOROIDALSPACE 



CIRCULAR 



BRES 

 CILIARY 

 PROCESS 



RADIATING FIBRES 

 OFZONULE OFZINN 

 ZONULE OF ZINN 

 ZONULAR SPACES 



POSTERIOR CHAMBER 

 OF EYE 



EPITHELIUM OF 

 LENS CAPSULE 

 CAPSULE 

 OF LENS 



ANGLE OF 

 ANTERIOR 

 CHAMBER 

 CANAL OF, 

 SCHLEMM 



CONJUNCTIVA 

 EPISCLERAL 

 CONNECTIVE- 

 TISSUE 

 LIGAMENTUM 

 PECTINATUM 

 IRIDIS 

 RIMA 

 CORNEALIS 



IRIS (ante- 



" rior surface) 



POSTERIOR 



SURFACE j- 

 OF CORNEA 

 EPITHELIUM j, 

 OF CORNEA 

 ANTERIOR-I 

 ELASTIC I" 

 LAMINA 



POSTERIOR ELASTiC 

 LAMINA 



CORTICAL SUBSTANCE 

 'OF LENS 



NUCLEUS 

 OF LENS 



STROMA OF IRIS 

 PIGMENTARY 

 LAYERS OF IRIS 



FIG. 820. The upper half oi a sagittal section through the front of the eyeball. (Toldt.) 



The changes produced in the lens by age are the following: 



In the fetus its form is nearly spherical, its color of a slightly reddish tint, it is not perfectly 

 transparent, and is so soft as to break down readily on the slightest pressure. A small branch 

 from the arteria centralis retinae runs forward, as already mentioned, through the vitreous 

 humor to the posterior part of the capsule of the lens, where its branches radiate and form a 

 plexiform network, which covers its surface, and they are continuous around the margin of the 

 capsule with the vessels of the pupillary membrane and with those of the iris. 



In the adult the posterior surface is more convex than the anterior; it is colorless, transparent, 

 firm in texture, and devoid of bloodvessels. 



In old age it becomes flattened on both surfaces, slightly opaque, of an amber tint, and 

 increases in density. 



Vessels and Nerves of the Globe of the Eye. The arteries of the globe of the eye are the 

 short posterior ciliary, long posterior ciliary, and anterior ciliary arteries, and the arteria centralis 

 retinae. They have been already described (p. (51 b). ~ * 



