424 THE CORNEA, BY ALEXANDER ROLLETT. 



after losses of substance,* and the regeneration of the tissue 

 which has been observed to occur, likewise demand a more 

 profound and searching investigation. 



THE EXTERNAL EPITHELIUM OF THE CORNEA. 



This epithelium is a laminated pavement epithelium, which 

 in Man is O03 of a millimeter in thickness.f The characters 

 of the external epithelium are very much alike in Man and 

 Mammals. 



Its most superficial layers are composed of many layers of 

 flattened cells, which are broader than those that are more 

 deeply situated, and which, seen in situ, as in sections of 

 hardened preparations, or in detached shreds of the epithelium, 



Fig. 388. 



Fig. 388. Ribbed and spinous cells from the middle cell layer of the 

 external corneal epithelium of the Pig, isolated by maceration of the 

 cornea in a ten per cent, solution of common salt, and subsequent treat- 

 ment with water. 



present a polygonal form. In teazed-out specimens of epithe- 

 lium prepared in iodine-serum, or for a longer period in a ten 

 per cent, solution of common salt, and subsequently for a short 

 time in water, these cells appear rough, slightly dentated, and as 

 ribbed, spiny, or prickle cells, with their inequalities interlock- 

 ing with each other (fig. 388). I have never been able to see 

 any cells provided with such long processes (digitate cells) as 

 ClelandJ states that he has isolated from the middle layers of 



* Bonders, Nederlandisch Lancet, 1848, p. 218. 



t Henle, loc. cit., p. 605. 



J Cleland, On the Epithelium of the Ox, Journal of Anatomy and 

 Physiology, by Humphry and Turner, Vol. ii. , pp. 362, 364. Cambridge 

 and London, 1868. 



