THE EYE. 345 



cells and forms a sort of spongy network between these and 

 the inner nuclear layer ; its composition is still a matter of 

 doubt, but it appears to be made up of a more or less homo- 

 geneous substance, in which are numerous fine openings filled 

 with some material of a peculiar refractive power. It does not 

 belong to the nervous substance of the retina, and when placed 

 in a 10 per cent, solution of common salt, dissolves, leaving the 

 supporting connective-tissue fibres unaffected. 



The inner nuclear layer is made up of numerous oval cells 

 with large nuclei ; they belong mostly to the nervous tissue, 

 but scattered among them are also cells of the supporting con- 

 nective-tissue framework. 



The nerve-cells resemble small bipolar ganglion-cells, hav- 

 ing two fine processes, the inner of which probably connects 

 with the ganglion-cell layer, or directly with the optic nerve 

 fibres. Near the macula these cells are more numerous ; to- 

 ward the ora serrata they gradually decrease in number. 



Next comes the outer granular layer, a thin stratum re- 

 sembling the inner in appearance and composition ; here the 

 fine fibres from the outer and inner nuclear layers become lost 

 in a tangled mass. 



Between this layer and the membrana limitans externa is 

 the outer layer of nuclei, made up of a number of oval cells, 

 connected more or less closely with the inner ends of the rods 

 and cones. 



The larger nerve-fibres, which pass through the outer gran- 

 ular layer, are joined to the nuclei of the cones, which lie di- 

 rectly within the membrana limitans and are connected to a 

 prolongation of the base of the cones themselves. The smaller 

 fibres pass to the nuclei of the rods, which form an irregular 

 layer at varying distances from the limiting membrane, and 

 from which fine tangled fibres pass to the base of the rods. 

 These nuclei resemble those of the inner layer ; they con- 

 tain a small amount of granular matter with a nucleus and nu- 

 cleolus, and sometimes exhibit, as the result of post-mortem 

 changes, peculiar transverse stripes. 



Directly beyond the membrana limitans externa, and rest- 

 ing upon it, are tlie rods and cones, each composed of an outer 

 ' and inner member. 



The rods are small, cylindrical bodies of high refractive 

 power ; when fresh they appear homogeneous, but with the 



