400 THE CORNEA, BY ALEXANDER ROLLETT. 



slightly developed in the Sheep, Ox, and Pig, and somewhat 

 better again in the Dog and Cat. 



After what has 'been already stated in regard to the struc- 

 ture of the matrix of the cornea, it appears that we cannot 

 speak with propriety of corneal lamellae. We must, then, de- 

 scribe the smooth fasciculi themselves as lamellae, which in a 

 certain sense is perfectly correct. 



The appearance of a lamellar structure, and the readily 

 demonstrable cleavability of the cornea in a direction parallel 

 to the surface, especially in specimens hardened in dilute 

 alcohol or in Miiller's fluid, depends on the superficial arrange- 

 ment and superimposition of the smooth fibrous fasciculi of the 

 cornea; these, however, are abundantly connected with one 

 another by fibrils running vertically to the surface. Respect- 

 ing the parts of adjacent superimposed fasciculi not thus con- 

 nected, but which still undergo the above-mentioned cleavage, 

 an account will hereafter be given. 



The fibrils of the cornea, and the fasciculi they compose, swell 

 in water, and become thicker. In acids (acetic acid, pyrolig- 

 neous acid, and very dilute hydrochloric acid) they also swell 

 up, especially in their transverse diameter; the fibrils and 

 fasciculi thereby become intimately compressed together, their 

 striae disappear, and the cells become granular, and their intei- 

 communications clearly visible, just as is the case with the 

 cells of connective tissue similarly treated with acids. 



In dilute alkalies the corneal fibrils also swell up. 



On boiling with water the cornea contracts considerably in 

 diameter, whilst it at the same time becomes much thicker. 

 The fasciculi of fibrils thus behave themselves just like those 

 of connective tissue ; and as in this latter case, if sections be 

 made from the cornea and boiled for a short time, and be then 

 dried, when these are again moistened the cells become clearly 

 visible. This plan was formerly much used for the demonstra- 

 tion of the corneal corpuscles. 



Both when the tissue has been swollen by immersion in 

 acids and by boiling in water, the fasciculi running through 

 the mass parallel to the surface of the cornea, and which be- 

 come much thicker transversely those fasciculi, namely, which 

 bend towards the surface become stretched and tense, and are 



