326 THE BLOODVESSELS OF THE EYE, BY TH. LEBER. 



globe of the eye. The vascular circle thus formed is completed 

 by branches of the anterior ciliary arteries, which pass directly 

 from the sclerotic to the ciliary muscle. By this means a 

 complete arterial circle is produced at the anterior border of 

 the muscle, termed the circulus arteriosus iridis major, which 

 is distributed chiefly to the iris and the ciliary processes, 

 whilst the arteries of the ciliary muscle and the rami recur- 

 rentes of the choroid are given off directly to it by the ciliary 

 arteries. 



In many animals in which the ciliary processes advance farther 

 upon the posterior surface of the iris, as for example in the Rabbit, 

 the circulus iridis major does not lie in the ciliary muscle, but in the 

 iris at a small distance from the ciliary border. 



In addition to the circulus iridis major, the long and anterior 

 ciliary arteries form still further backwards in the ciliary 

 muscle an incomplete circle of anastomoses. 



The arteries of the ciliary muscle branch in an arborescent 

 manner, and following the direction of the muscular fasciculi, 

 form a tolerably dense trellis-like plexus, which differs in a 

 very marked manner from the plexus of the subjacent ciliary 

 processes. 



The arteries of the ciliary processes proceed from the cir- 

 culus iridis major, and must all therefore, like those of the 

 iris, first pass through the ciliary muscle. They are small 

 brandies, which quickly break up into a large number of 

 branches that frequently anastomose with each other, and 

 gradually dilating become continuous with the commencement 

 of the veins. Owing to their frequent anastomoses, these capil- 

 lary veins form a very rich vascular plexus that constitutes 

 the principal portion of the ciliary processes. 



The remarkable increase in the extent of surface caused by the 

 numerous larger and smaller lamelliform processes and the intervening 

 channel-like depressions, the great width of the capillary veins, the 

 resulting retardation of the current of the blood, and the thinness of 

 the walls of the vessels, co-operate in rendering the ciliary processes 

 the chief agents for the secretion of the intraocular fluids. 



The arteries of the iris spring from the anterior border of 

 the circulus arteriosus major, in the form of numerous and 



