NERVES OF THE CORNEA. 429 



varies in different animals. In Man the number is variously 

 stated at from twenty to thirty,* twenty-four to thirty- 

 six,-!- and forty to forty-five. J In the Rabbit, from twenty 

 to thirty ; in the Ox and Sheep, from ten to twenty ; in the 

 Fowl and Pigeon, from twelve to eighteen ; in the Guinea- 

 pig, from fifteen to eighteen ;|| and in the Frog, on the average, 

 fifteen^ have been counted. In the course of their dis- 

 tribution in the substance of the cornea, the nerves form a 

 plexus characterized by its numerous anastomoses, the fine 

 branches of which run towards the anterior surface, where 

 another plexus is found close beneath the epithelium, and just 

 under the anterior structureless lamella.** The nerve plexus 

 formed of non-medullated fibres presents the same appearance 

 in Man and the most diverse animals,ff and in the Frog the 

 fine extremities of the nerves distributed through the whole 

 cornea are connected with the corneal corpuscles. JJ 



In Mammals, the fibres emanating from the outer parts of 

 the nerve plexus may be followed into the anterior epi- 

 thelium of the cornea. The best insight into the mode of 

 distribution and the termination of the nerves in the cornea, 

 has been obtained by Cohnheim,||[| by the use of solution of 

 chloride of gold, which is so admirably adapted for this pur- 

 pose. His beautiful results have been in part corroborated 

 both by Kolliker and by Engelmann. 



At a short distance from the margin of the cornea, the 



* Kolliker, Mikroskopische Anatomie, Band ii., p. 627. 



f Kolliker, Gewebelehre, p. 650. Leipzig, 1867. 



J Samisch, Beitrage zur normalen und pathologischen Anatomie desAuges. 



Kolliker, Mikroskopische Anatomie, Band ii., p. 627. 



|| Cohnheim, Virchow's Archiv, Band xxxviii., p. 354. 



*fT Kiihne, Untersuchungen uber das Protoplasma, etc. , p. 133. Leipzig, 

 1864. 



** Kolliker, loc. cit., p. 627. 



ft His, Beitrage zur normalen und pathologischen Anatomie der Cornea, 

 p. 60. J. Arnold, Bindehaut der Hornhaut. Samisch, loc. cit. Ciaccio, 

 Quarterly Journal of Microscopical Science, July, 1863, p. 177. Kiihne, 

 loc. cit. 



Kiihne, loc. cit. 



Hoyer, Reichert and Dubois-Reymdnd's Archiv, ]866, p. 180. 



|| 1 1 Cohnheim, loc. cit., p. 343. 



