SECT. 224.] VESSELS OF THE CORNEA. 543 



isolated streaks of epithelial cells, mostly elongated, or even fusiform, 

 are continued over the fibrous networks of the lig. pectinatum 

 (enclosing its elements) to the border of the iris, where a complete 

 epithelial layer again appears. 



In the adult, the cornea is almost entirely destitute of vessels ; 

 while, on the other hand, as J. Midler and Henle (De Membr. 

 Pupill., p. 44) first observed, a rich vascular network occurs in the 

 embryonic conjunctiva cornea; in man and in the sheep, but this 

 does not appear to extend as far as the middle of the cornea. 

 Towards the end of foetal life, this network becomes indistinct in 

 man more than in animals, so that in the human cornea blood- 

 vessels are met with only at the border, in a ring of half a line, or 

 at most, of one line in breadth. They are mostly fine and finest 

 capillaries, o - oo2'" to o - oo4'" in diameter, which form one or more 

 series of curves, and thus terminate ; they likewise lie in the sub- 

 stance of the conjunctiva, which here extends as a demonstrable 

 lamina for some distance upon the cornea, and then terminates in 

 its anterior structureless layer. These superficial, or conjunctival 

 vessels also occur in animals, but are much more beautiful, and 

 extend further inwards, often to one-half the radius of the cornea, 

 or even further. In addition to these, deeper capillaries, derived 

 from the sclerotic, occur in the cornea itself, and these mostly 

 accompany the nervous trunks ; in these they either form one or 

 more very elongated loops, or they extend a little beyond them : 

 they invariably terminate by the loops, whose finest vessels, as in 

 the superficial capillaries, measure scarcely more than 0*002'" in 

 diameter. I have likewise seen these proper corneal vessels in 

 man, but not constantly, and never so well developed as in the 

 lower animals. 



Nothing certain is known of the lymphatic vessels of the cornea 

 (compare, also, Arnold, Anat., ii. p. 988); but I have recently ob- 

 served some peculiar vessels in the cornea of a young cat, which I 

 can scarcely consider as being anything else than lymphatic vessels. 

 At the border of the cornea, along with very distinct capillary 

 loops containing blood-corpuscles, there were found pale vessels of 

 much greater width (o*oi'" to o , 02'", or even eve^"' in diameter), 

 which either extended singly into the cornea, as far as the blood- 

 vessels, and then terminated with bulbous or pointed extremities, 

 or else formed simple loops of two, three, or more together, from 

 which loops other coecal processes were frequently given off. Not- 

 withstanding their width, these vessels possessed a delicate, struc- 

 tureless coat, with scattered nuclei, and they contained in their 



