18 



INNERVATION. 



[CHAP. xvn. 



elaborate structure. It is in fact composed of five coats or layers, 

 clearly distinguishable from one another. These are, from before 

 backwards, the conjunctival layer of epithelium, the anterior elastic 

 lamina, the cornea proper, the posterior elastic lamina, and the 

 epithelium of the aqueous humour, or posterior epithelium. The 

 cornea, when uninflamed, contains no blood-vessels j those of the 

 surrounding parts running back in loops, as they arrive at its 

 border. 



On the cornea proper, or lamellated cornea, the thickness and 

 strength of the cornea mainly depend. It is a peculiar modifica- 

 tion of the white fibrous tissue, continuous with that of the sclerotic. 

 At their line of junction (fig. 109), the fibres, which in the sclerotic 



Pig. 109. 



Vertical section of the Sclerotic and Cornea, shewing the continuity of their tissue between the 

 dotted lines : a. Cornea, b. Sclerotic. In the cornea the tubular spaces are seen cut through, 

 and in the sclerotic the irregular areolte. Cell-nuclei, as at c, are seen scattered throughout, 

 rendered more plain by acetic acid. Magnified 320 diameters. 



have been densely interlaced in various directions, and mingled 

 with elastic fibrous tissue, flatten out into a membranous form, so as 

 to follow in the main the curvatures of the surfaces of the cornea, 

 and to constitute a series of more than sixty lamellae, intimately 

 united to one another by very numerous processes of similar struc- 



Fig.no. 



Tubes of the Cornea Proper, as shown in the eye of the ox by mercurial injection. Slightly magnified 



