428 THE CORNEA, BY ALEXANDER ROLLETT. 



corneal epithelium. We have already seen that processes are present 

 even in the normal condition in the cells of the middle layers. 

 Heiberg* describes slow and gradual changes of form in the processes 

 of the epithelium undergoing regeneration. F. A. Hoffinanf had pre- 

 viously observed the protrusion and retraction of rounded processes in 

 the cells of the anterior corneal epithelium in the vicinity of the eschar 

 of the cornea caused by nitrate of silver. The regeneration of the 

 epithelium in a cavity (the size of which is unfortunately not stated) 

 caused by scratching the centre of the surface of the cornea with a 

 cataract needle is accomplished in Frogs in about forty hours, or as a 

 rule before the end of the third day, and in Mammals and Birds within 

 twenty-four hours. After these periods had elapsed, the cavities were 

 found to be completely filled up by cicatrisation.]: 



Migrating cells occur in the anterior corneal epithelium, just 

 as in the corneal tissue, and such cells are also found between 

 the two tissues (epithelial and subepithelial migrating cells).) 

 Engelmann,[| J. Arnold,^ Wads worth and Eberth** F. A. 

 HotTman,tf and Heiberg,}} consider it doubtful whether the 

 migrating cells take any part in the regeneration of the 

 epithelium after losses of its substance. 



THE NERVES OF THE CORNEA. 



The nerves of the cornea enter its margin at tolerably regu- 

 lar distances from each other in the form of trunks of various 

 size. The entrance of medullated nerves into the cornea has 

 long been known to occur. 



The number of such medullated nerves entering the cornea 



* Loc. cit., p. 12. 



t Ueber Contractilitatsvorgange im vorderen Epithel der Frosdiliomhaut. 

 Diss. inaug. Berlin, 1861. 



J Heiberg, loc. cit., p. 10. 



v. Recklinghausen, Virchow's Archiv, Band xxviii., p. 191. 



|| Engelmann, loc. cit., p. 15. 



IF J. Arnold, loc. cit., p. 170, et seq. 



** Wadsworth and Eberth, loc. cit., p. 370. 



ft F. A. Hoffman, loc. cit., p. 384. 



J$ Heiberg, loc. cit. , pp. 13 and 20. 



Schlemm, Berliner Encyclopddie, Band iv., p. 22. Bochdalek, Bericht 

 uber die Versammlung der Naturforscher in Prag im Jahr., 1837, Prag, 

 1838, p. 182. 



