38 



THE EY r E. 



panied the prolongation of the .central artery of the retina along the canal of Stilling 

 (fig. io) through the vitreous body to the capsule of the lens ; in some eyes this tissue can 

 be followed for some distance into the vitreous humour. 



n se par fa 



Fig. 47. SECTION THROUGH THE PLACE OP ENTRANCE OF THE OPTIC NERVE (B), TOGETHER WITH THE 



OPHTHALMOSCOPIC VIEW OF THE DISC (A), TO SHOW THE CORRESPONDING PARTS OF THE TWO. 



(Fuchs, after Jaeger. ) 



c, d, lines of correspondence ; b, depression in centre of disc ; r, retina ; ch, choroid ; si, so, inner 

 and outer parts of the sclerotic coat, s : ci, a ciliary artery cut longitudinally ; a, r, central artery and 

 vein ; sd, subdural space ; sa, subarachnoid space ; du, dural sheath ; ar, arachnoidal sheath of nerve ; 

 p, pial sheath : n, nerve bundles ; se, septa between them. 



MICROSCOPIC STRUCTURE OP THE RETINA. 



"When vertical sections of the retina, i.e., sections made perpendicularly to its 

 surface, are submitted to microscopic examination, eight distinct; strata are recog- 

 nizable, together with certain fibrous structures which pass vertically through the 

 membrane and connect the several layers. 



The following are the designations of the layers, from within outwards : 



1. The layer of nerve-fibres (stratum opticum). 



2. The layer of nerve-cells (ganglion nervi optici). 



3. The inner molecular layer (stratum reticulare internum}. 



4. The inner nuclear layer (stratum granularum internum, ganglion retinae). 



5. The outer molecular layer (stratum reticulare externum). 



6. The outer nuclear layer (stratum granularum externum). 



7. The layer of rods and cones (stratum bacillorum). 



8. The layer of hexagonal pigment cells (stratum nigrum). 



In addition to these eight strata two very delicate membranes have been 

 described the one, membrana Umituns interna, bounding the retina on its inner 

 surface, next to the hyaloid membrane of the vitreous humour ; the other, memlrana 



