VII. 



THE CORNEA. 

 BY ALEXANDER ROLLETT. 



THE cornea of the 63-6 of vertebrate animals is composed of 

 several layers of tissue, presenting different characters. The 

 anterior and posterior surfaces of the layers run nearly parallel 

 to the surface of the cornea, as far as to the margin of the 

 cornea (limbus cornece), where they are bounded by the con- 

 junctiva, the sclerotic, and the ligamentum pectinatum iridis. 



LAYERS OF THE CORNEA. (Fig. 377.) 



The layers of the cornea, enumerated from .without inwards, 

 are as follows : 



1. The external epithelium of the cornea (fig. 377, ci 6). 

 This is a laminated pavement epithelium. 



2. The proper tissue of the cornea (substantia propria, seu 

 fibrosa cornese, lamellated or fibrous tissue of the cornea, fig. 

 377 ? 5 c ) t The connective tissues of the cornea are included 

 in this layer. 



3. The membrane of Descemet (membrane of Demours, mem- 

 brana humoris aquei, vitreous lamella of the cornea, lamina 

 elastica posterior of Bowman, internal basement membrane of 

 Henle, fig. 377, c d). This is a sharply defined lamella, usually 

 of homogeneous aspect. 



4. The endothelium of the membrane of Descemet (internal 

 epithelium of the cornea, epithelium of the membrane of 

 Descemet, epithelium humoris aquei, fig. 377, d e). This is a 

 simple layer of flattened cells. 



The succession of layers just described as existing in the 

 cornea may be easily followed in vertical sections of specimens 



