ARTERIES OF THE CILIARY BODY AND IRIS. :j:>5 



wards to the ciliary processes and the iris. The admission 

 formerly made of the presence of such branches depends on the 

 veins that pass from the ciliary processes to the venae vorti- 

 cosae having been mistaken for them. On the other hand, the 

 most anterior portion of the choroid receives a number of 

 recurrent branches* from the ciliary body, which proceed from 

 the long posterior and anterior ciliary arteries. These, varying 

 in number and size, run backwards at considerable distances 

 from each other, between the numerous parallel veins of the 

 orbiculus ciliaris, supplying the most anterior portion of the 

 choroid with capillaries, and also partially anastomosing with 

 the terminal branches of the short posterior ciliary arteries. 



The capillary plexus forms a uniform layer covering the 

 whole internal surface of the choroid from the optic-nerve 

 entrance to the margin of the orbiculus ciliaris (which corre- 

 sponds to the ora serrata of the retina), and here terminates 

 with an irregularly dentated margin. Near the optic nerves 

 the meshes are irregularly rounded and very small; but in 

 proportion as they are more distant from, the nerve they 

 become more elongated in form, the long diameter ulti- 

 mately becoming from eight to ten times longer than the short. 

 Moreover, the diameter of the capillaries themselves becomes 

 somewhat greater. There are no true capillaries in the orbi- 

 eulus ciliaris. 



(2.) ARTERIES OF THE CILIARY BODY AND OF THE IRIS. 



The two long posterior ciliary arteries, after their passage 

 through the sclerotic, are situated on the external surface of the 

 choroid, and run without dividing horizontally forwards to the 

 ciliary muscle. Here they divide into two branches, which 

 separate at an acute angle, and penetrate into the substance of 

 the muscle, and having reached the anterior border curve round, 

 so that the two branches of each artery together encircle the 



* These recurrent branches were first described and depicted by Haller, 

 (Tabulae arteriarum oculi, Tab. vi.,fig. 4), and subsequently by Zinn (De- 

 xcr't[>tio anatom. ocul. human, ed. by H. A. Wrisberg, Gottingen, 1780, 

 p. 39), whose account, however, had fallen into oblivion until I rediscovered 

 it (loc. cit.j pp. 303 and 306, Taf. ii., fig. 12). 



