THE EYE. 247 



ment (6) is constituted by the cornea. These membranes 

 enclose a black stratum, the so-called uvea. It consists of the 

 choroid (e) with the ciliary processes (g) and, applied exter- 

 nally to the latter, the ciliary muscle (_/") and, finally, a more 

 anterior ring-shaped disk, the iris (//). 



The contents of the hollow ball are formed by the various 

 light-refracting media. Even the cornea {b) participates in 

 this action. Next to it comes the so-called humor aqueus, 

 that is, the watery contents of the anterior and posterior 

 chambers of the eye (in front of /). Then follows a firmer 

 structure, the most important refracting body, the crystalline 

 lens (/). The completion is formed by a large globular mass, 

 having a concave impression in front, the vitreous body or 

 humor vitreus (behind /). 



The greater portion of the latter is covered by the cup- 

 shaped expansion of the optic nerve, the retina (/). It termi- 

 nates anteriorly, according to the usual impression, in the 

 region of the origin of the ciliary processes, with an undulated 

 border, the so-called ora serrata (k). 



A very complicated system of vessels, springing almost 

 exclusively from the arteria ophthalmica, supplies our organ 

 with blood. Lymphatics are, naturally, also not wanting. 



The cornea, with its two homogeneous boundary layers, was 

 mentioned at p. 56; the stratified pavement epithelium of the 

 anterior surface at p. 31 ; the simple cell layer of the posterior 

 at p. 29 ; the nerves at p. 207. 



We mentioned at that time the system of passages of the 

 cornea, and ascribed to them a sort of parietes. Differences 

 of opinion prevail concerning this, however. The passages 

 of this system of juice-clefts (Fig. 200) may be artificially filled 

 by the puncturing method, in successful cases, with the pres- 

 ervation of their old shapes, in numerous others, however, 

 distorted, with the appearance of wide misshapen canals. 

 They have been not badly termed "rupture spaces." The 

 circumstance is interesting that a successful injection of the 

 juice-spaces finally leads to the lymphatics of the conjunctiva. 



The cellular contents of the canal-work has caused endless 



