THE EMBRYOLOGY OF THE EYE. 25 



the vessels in the papilla and run in the retina 

 just external to the limitans interna (Fig. lo to 

 the left), but do not pass through the limiting 

 membrane and therefore do not anastomose 

 with the vessels of the lens-sheath or of the 

 vitreous. 



The blood from the retinal vessels is re- 

 turned to the papilla. The blood from the 

 vitreous-vessels circulates in the lens-sheath 

 and is carried out of the eye by vessels of the 

 iris, which anastomose with the vessels of the 

 anterior portion of the lens-sheath. Most 

 writers have considered the retinal vessels as 

 being at first one system of the vitreous-ves- 

 sels. The retinal vessels are, however, from 

 their first appearance always separated from 

 the vitreous by the limitans interna. 



The vitreous has shown, up to this period, 

 a slightly fibrillar structure, the direction of 

 the fibrillae being in general parallel to the 

 margin of the vitreous (Fig. 9). Now, well- 

 marked coarser striations appear about the 

 blood-vessels and run parallel to them (Fig. 1 2). 



