THE EYE. 381 



in 4 or 5 main branches. Lodged at first only beneath the 

 membrana limitans, these vessels penetrate through the layer of 

 nerve-fibres into that of grey nerve-substance, ramify in an 

 elegant arborescent manner as far as the ora serrata, and pass 

 by their terminal prolongations on all sides into a rather wide- 

 meshed network of very fine capillaries (0002 — 0-003"'), which 

 is lodged chiefly in the grey layer, but partly also in the 

 expansion of the optic nerve. In animals, the veins commence 

 with a complete circle, circulus venosus retince, at the ora 

 serrata, accompany the arteries in single trunks, and converge 

 to the vena centralis, which quits the eye together with the 

 artery. No large vessels exist in the "yellow spot," where 

 there are only numerous capillaries. I have never yet met with 

 nerves on the retinal vessels, whilst on the outside of the 

 larger vessels I have occasionally noticed traces of an accom- 

 panying fibrous tissue, approaching nearest to the embryonic, 

 reticular connective tissue. 



[The radiating fibre-system of the retina, though known in 

 its separate parts to older and more recent observers, had not 

 been comprehended in its connexion, and we are very greatly 

 indebted to H. Miiller for his accurate investigations into this 

 important structure in animals of every class. I have repeated 

 Miiller's observations in the human eye, which was not investi- 

 gated by him, and have been enabled to confirm in it all that 

 he has stated, and in some respects to carry the observations 

 further. The reason why the radiating fibre-system and the 

 relation of the " rods" to it has hitherto remained unknown, is 

 because no one except Bowman, so far as I am aware, has en- 

 gaged in the indispensable study of vertical sections of the retina, 

 and moreover, because no one had thought of applying chromic 

 acid to that tunic, which has elsewhere in the nervous tissues 

 been of such important service, and although I had particularly 

 shown that the multipolar retinal cells were well preserved in 

 it. If parts still fresh be taken for examination, in transverse 

 sections and chromic acid preparations, very satisfactory views 

 of the structures above described will be obtained, and it 

 will excite surprise that such numerous fibres pervading 

 the entire retina should have been hitherto overlooked. A 

 wholly new investigation of the retina has commenced with 



