8l6 PRELIMINARY ANATOMICAL AND HISTOLOGICAL OBSERVATIONS. 



these channels from without, and increase greatly in the presence of inflammation. 

 (4) The transparent, structureless posterior elastic membrane (d), 0.006 mm. 

 thick, Descemet's or Demour's membrane, possesses in many animals a striated 

 appearance indicative of a lamellar structure, and toward the corneal periphery, 

 where it becomes thicker, it occasionally exhibits slight conical projections. This 

 membrane is exceedingly tough and* (in the presence of inflammation, etc.) re- 

 sistant; when it is detached, it curls up toward its convex side. Its peripheral 

 portion passes over into the fibre-elastic network of the pectinate ligament of the 

 iris, the trabeculae of which are lined with epithelial cells. (5) The posterior 

 corneal epithelium is composed of a single layer of flat, delicate, hexagonal, nucleated 



FIG. 266. Meridional Section through the Corneoscleral Junction: a, Anterior corneal epithelium; b, Bowman's 

 membrane; c, corneal corpuscles or lymph-spaces; I, corneal lamella; the layer between b and d is the true 

 tissue of the cornea; d, Descemet's membrane; e, its epithelium; /, junction of the cornea and the sclera; 

 g, hmbus .conjunctivas; h, conjunctiva; , Schlemm's canal; k, Leber's venous plexus, considered by Leber 

 as belonging to Schlemm s canal; m m, meshes in the tissue of the pectinate ligament of the iris; n, root 

 of the iris; o longitudinal, p circular (transversely divided) fiber-bundles of the sclera; q, perichoroidal space; 

 s meridional, / equatorial (circular) bundles of the ciliary muscle; , section of a ciliary artery; v, epithelium 

 f the ins (continuation of that on the posterior surface of the cornea); w, stroma of the iris; x, pigment of 

 the iris; z, a ciliary process. 



cells (/), bound together by fine processes, the attached portions of which have 



fibrous appearance. These cells extend from the edge of the cornea onto the 



surface of the ins (v). In the interspaces between the individual cells 



here arettne lymph-spaces that communicate with a delicate canal-system beneath 



the epithelial layer, and, further, through Descemet's membrane, with the corneal 



lacunae. 



The nerves of the cornea arise from the large and short ciliary nerves, and are 



tly sensory m function. They enter the margin of the cornea as trunks that 



;s medullary sheaths. Further inward the sheaths are lost, and the nerves 



form a network on the surface of the cornea. The branching, naked fibrillae 



