98 EICHAED ASSHETON. 



Connected with the outer molecular layer are certain neuro- 

 blasts of the inner nuclear layer (X). 



Among the cells of the outer nuclear layer are some with 

 long, broad prolongations {FR.), the radial or Miillerian 

 fibres of the adult. 



These fibres are not easily traced to the " outer limiting 

 membrane'^ in the centre of cup, but may be more easily seen 

 towards the rims, Avliere the rods and cones are not so 

 crowded {FR). Compare these with the cells marked SP in 

 fig. 12. 



Certain neuroblasts (NI.) of the inner nuclear layer seem to 

 send processes into the inner molecular layer, but my observa- 

 tions do not enable me to say whether they break up into 

 fibrils, or whether they pass through and on to the brain. 



Within the inner molecular layer comes a double row of 

 cells, the ganglionic layer. In many cases these cells are pro- 

 duced into short deeply staining processes towards the inner 

 molecular layer, and break up at once into fine fibrils (G.). 



The growth of these processes seems to be the prime cause of 

 the appearance of the inner molecular layer. 



These processes just described appear to be a later develop- 

 ment than the process from the opposite pole, which forms a 

 fibre of the optic nerve. 



These are seen at N, near the rim of the cup, as thick black 

 prolongations, while the other pole is still round, and shows 

 as yet no signs of the processes described above, which form, 

 at any rate in part, the inner molecular layer. 



So also, if the other elements of the eye be traced through 

 the section, it can be noticed that as they near the rim they 

 are less and less differentiated, until they all merge into a mass 

 of rapidly dividing cells, each one very like to his neighbour. 



The Choroidal Fissure. 



At one point of the rim, however, there is no proliferation 

 of cells, and therefore at this point the wall of the optic cup 

 does not grow. This point is that over which the fibres from 



