244 



THE KETINA, BY MAX SCHULTZE. 



terminal organs of the optic nerve. The anatomical connection 

 is perfectly clear, since it may be seen that each flask-shaped 

 cone situated outside the membrana limitans externa is con- 

 tinuous with a granule, whilst each rod-fibre is continuous 

 with a rod, which either springs directly from a rod granule, 



Fig. 351. 



Fig. 351. From the posterior part of the retina of Man. 6, 

 External granulated layer ; 7, external granule layer ; 8, limitans 

 "externa ; 9, rods and cones, the external segments of which are 

 sharply denned from the internal. Magnified 800 diameters. The 

 supporting fibres of connective tissue are omitted in this drawing. 



if the granule be placed just beneath the membrane, or if 

 not, with the intervention of a thicker portion of the fibre. 

 The layer of rods and cones thus covers like a wood of close- 

 set palisades the outer surface of the external granule layer, 

 and completes the formation of the retina as a nervous ex- 

 pansion. The conversion of luminous waves into nerve move- 



