430 



THE CORNEA, BY ALEXANDER ROLLETT. 



medullated nerve fibres suddenly lose their medullary sheath. 

 The point at which this occurs is not constant (Cohnheim), 

 sometimes occurring in the small entering trunklets, some- 

 times in the branches of the first, second, or even the third 

 order into which these break up. 



The nerves in their further course from this point are com- 

 posed of a variable, but usually very large, number of extremely 

 delicate non-medullated nerve fibres. These fasciculi of non- 

 medullated fibres enclose long oval nuclei, which cannot, how- 

 ever, be certainly shown to belong to any investing sheath. 



Fig. 390. 



Fig. 390, Nerves of the cornea of a Pig, as seen in a vertical 

 section made from a specimen treated with chloride of gold. 

 a a, Larger nerves ; b b, plexus beneath the anterior limiting layers 

 of the cornea ; c c, subepithelial plexus ; d d, the terminal branches 

 ascending through the epithelium. 



The individual medullated fibres often exhibit a very beautiful 

 varicose appearance. These numerous fibres must obviously 

 originate in a division or fibrillation of the axis cylinder (Max 

 Schultze). 



The fibres just described as entering the corneal tissue then 

 form, by their manifold branching, communications, and diver- 

 gences, a rich plexus (fig. 390), which presents larger meshes, 

 and is composed of stronger nerves in the deeper part of the 



