750 



THE EYE AND VISION. 



[CH. LV. 



in different parts of the retina : it consists of non-medullated 

 fibres which interlace, and some of which are continuous with 

 processes of the large nerve-cells forming the next layer. The 

 fibres are supported by the sustentacular fibres. They become 

 less and less numerous anteriorly and end at the ora serrata. 

 3. Layer of ganglion cells. This consists of large multipolar 



nerve-cells with large and 

 round nuclei, forming either 

 a single layer, or in some 

 parts of the retina, especi- 

 ally near the macula lutea, 

 where this layer is very 

 thick, it consists of several 

 strata of nerve-cells. They 

 are arranged with their 

 single axis-cylinder pro- 

 cesses inwards. These pass 

 into and are continuous 

 with the layer of optic 

 nerve - fibres. Externally 

 the cells send off several 

 branched processes which 

 pass into the next layer. 



4. Inner molecular layer. 

 This presents a finely 

 granulated appearance. It 

 consists of neuroglia tra- 

 versed by numerous very 

 fine fibrillar processes of the 

 nerve-cells just described, 

 and the minute branchings 

 of the processes of the bi- 

 polar cells of the next layer. 



5. Inner nuclear layer. 

 This consists chiefly of 



Inner limb -fa 

 of rod. 



Rod fibre. 



Bipolar cell. _ 



Fig. 571. Diagram showing the nervous ele- 

 ments of retina, i, nerve fibre of ganglion 

 cell ; 2, processes of ganglion cell going out- 

 wards : 3, nerve fibre passing direct to bipolar 

 cell in inner nuclear layer ; 4, process of gan- 

 glion cell towards bipolar cell ; 5, fibre from 

 cone-granule breaking up into fibrils which 

 arborise round the branches of bipolar cells. 

 (From McKendrick, after Stohr.) 



numerous small round cells, 

 with a very small quantity 

 of protoplasm surrounding 



a large ovoid nucleus; they are generally bipolar, giving off one 

 process outwards and another inwards. One process passes inwards 

 to form a synapse with the arborisation of a ganglion cell, 

 the other outwards to similarly arborise with the branchings of 

 the rod and cone fibres. Some cells, called spongioblasts, or 

 amacrine cells, however, only send off one process, which passes 



