LYMPHATICS OF THE RETINA. 



337 



the surface of the choroid with solutions of nitrate of silver. 

 At those points where the ocular muscles are attached to the 

 bulbus the continuity of the cavity of Tenon is interrupted ; it 

 is not, however, continued into the sheaths of the tendons, but 

 is on that side completely closed. In Mammals, owing to the 

 attachment of the musculus retractor bulbi (fig. 369, m retr), 

 it is divided into an anterior larger, and a posterior smaller 

 cavity. 



Fig. 370. 



Fig. 370. Diagrammatic representation of the passage of a vena 

 vorticosa, with its perivascular space, through the sclerotic, as seen in 

 the Pig. r, Retina ; c/i, choroid ; pch, perichoroidal space filled with 

 injection ; scl, sclerotica ; , Tenon's space ; v, vena vorticosa. 



At the posterior pole of the eye, and around the point of 

 entrance of the optic nerve, the cavity of Tenon communicates 

 with another lymphatic space which, like a sheath, invests the 

 external fibrous sheath of the optic nerve, and on account of its 

 position may be termed the supravaginal space (fig. 369, spv). 

 This finally opens through the canalis opticus into the arach- 

 noid space of the brain, which last, as is shown by injections 

 beneath the dura mater, communicates directly with the lymph- 

 atics of the neck. 



t 



B. The Lymphatics of the Retina. 



The lymphatics of the retina, as His (7, 8) discovered, form 

 sheaths to the bloodvessels of this membrane. They are peri- 



VOL. III. Z 



