chap, xxxvi.] THE CORNEA. 297 



fibrils are seen here and there. Between the lamellae 

 are left the lacunae and canaliculi for the branched, 

 flattened, nucleated corneal corpuscles, described in 

 a previous chapter (Figs. 25, 26). They anasto- 

 mose with one another within the same plane, and 

 also, to a limited degree, with those of neighbouring 

 planes. 



411. (4) The membrana Descemcti, or elastica 

 posterior, is a resistent elastic membrane, conspicuous 

 by its thickness in all cornese. 



(5) The posterior surface of this membrane is 

 covered with a mosaic of beautiful polygonal endo- 

 thelial cells, each with an oval nucleus the en- 

 dothelium of Descemet's membrane. Under stimu- 

 lation these cells contract. At first they appear 

 slightly and numerously branched, but gradually 

 their processes become longer and fewer, and 

 ultimately they are reduced to minute clumps 

 of nucleated protoplasm, each with a few long pro- 

 cesses. 



There are no blood-vessels in the normal cornea, 

 except in fcetal life, when there is underneath the 

 anterior epithelium a plexus of capillaries. 



The lymphatics are represented as the inter- 

 communicating lymph-canalicular system i.e., the 

 lacunae and canaliculi of the corneal corpuscles ; and 

 in connection with these are lymph channels lined 

 with a continuous endothelium and containing the 

 nerve bundles. 



412. The nerves (Figs. 68, 69, 70) are distri- 

 buted as the nerves of the anterior layers, and as 

 those of the Descemet's membrane. The first form 

 rich plexuses of fibrillated axis cylinders, with trian- 

 gular nodal points (Cohnheim), in the anterior layers of 

 the ground substance ; from this plexus pass obliquely 

 through Bowman's membrane short branches the 

 rami perforantes (Kolliker) and these immediately 



