THE EPIDERMIS. 



31 



we meet with flattened, not inconsiderable cells. In the 

 middle layers these elements become smaller, but taller, more 

 round, and, in the deepest layer {/?), at last, cylindrical. 



Fig. 36. — The cornea of the rabbit in vertical transverse section, after treatment with chloride 

 of gold ; a, the oldar, /', the young epithelial cells of the anterior surface ; c, corneal ti-sue : </, a 

 nerve branch ; e, finest nerve fibres or primitive hbriUae ; /, their distribution, and termination in 

 the epithelium. 



With a greater increase of the epithelial stratification, the 

 number of the upper and middle cell layers is much more 

 considerable. 



All the cells have a nucleus. The lowermost have a soft 

 protoplasma body ; the superficial (Fig. 7) have become more 

 solid and harder; they consist of corneous matter, or kera- 

 tine, a derivative of the albuminous group. These cornified 

 cells absorb weak alkaline solutions with avidity, becoming, 

 at the same time, distended to a globular form. 



A vertical transverse section, after the manner of our draw- 

 ing, favors the supposition that our cells have a pretty regu- 

 lar form. 



When, however, the cell cement has been dissolved by a 

 suitable macerating medium, an entirely different appearance 

 is presented. The stratified pavement epithelium now ap- 

 pears very much more like extremely polymorphous cells. 

 They lock into each other with their pointed and leaf-like 

 processes ; the convex surface of one cell is in contact with 

 the concave surface of its neighbor ; the surface is rough and 



