THE VESSELS OF THE CORNEA. 417 



morphological elements float, and in which the migrating 

 cells, pushing aside these morphological elements, can pur- 

 sue their destined path* is not in accordance with the 

 phenomena observed. It must be left for future researches 

 to decide whether transuded fluids cause, or are capable of 

 causing, forcible separation of the corneal tissue, like that 

 produced by puncture injections, and whether in such tran- 

 sudates formed elements resembling amoeboid cells are present. 



THE VESSELS OF THE CORNEA. The central portion of the 

 cornea in adult vertebrate animals is destitute of bloodvessels. 



In Man there is only a marginal zone of delicate capillary 

 loops, with a diameter of from one to one and a half millimeters. 

 These arise from the arteries running in the outer layer 

 of the most anterior part of the conjunctiva bulbi, and 

 discharge themselves into the subjacent veins of the same 

 membrane (fig 387). 



For the origin of these arteries, and the mode of formation 

 of the veins, the reader is referred to the chapter in this 

 Manual on the " Bloodvessels of the Eye." 



According to Leber, in the eye of Man there are no deeper- 

 lying vessels entering the deeper parts of the cornea from the 

 sclerotic. 



Iir Man, after death, the vascular loops at the margin of the 

 cornea may frequently be seen very beautifully injected 

 naturally. As a rule, elongated and wide-rneshed loops may 

 be seen naturally injected in the perfectly fresh eye of the 

 Sheep. 



In the eye of the fcetus a delicate capillary plexus is dis- 

 tributed over the whole of that layer of the anterior surface 

 of the cornea on which the anterior epithelium rests. 



Isolated and doubtful observations have been made by 

 Kolliker,^ His,J and Samisch, respecting the presence of 

 lymphatics at the margin of the cornea. The statements of 



. * Engelmami, loc. cit., p. 6, et seq. 



f Mikroskopische Anatomie, Band ii., p. 621. 



$ Beitrcige zur normalen und pathologischen Histologie der Cornea, p. 71. 



Beitrcige zur normalen und pathologischen Anatomie des Auges, p. 12. 

 Leipzig, 1862. 



VOL. III. E E 



