THE ORGANS OF SENSE. 



117 



a single rod bipolar of the inner nuclear layer. The cones are shorter 

 and thicker than the rods, and each consists of an outer and an inner 

 segment. The outer segment is conical and is transversely striated. 

 The inner segment is vertically striated in its outer two-thirds and 

 granular in its inner third. The continuation of the cone in the outer 

 nuclear layer is a comparatively thick fibre which contains a nucleus 

 immediately under the outer limiting membrane. The cone fibre 



Membrana 

 limitans interna. -- 



Stratum opticum. "] ^= 

 Ganglionic layer. 



Inner molecular 

 layer. 



Centrifugal fibre. 



Inner nuclear... 

 layer. 



Fibre of Miiller 



Outer molecular 

 layer. 



Outer nuclear 

 layer. 



Membrana 

 limitans externa. 



Layer of rods - 

 and cones. 



Diffuse amacrine 

 cell. 



"'Amacrine cells. 

 Horizontal cell. 



'/ Rod granules. 

 Cone granules. 



. , 



o"l" Pigmented layer. 



FIG. 33. Plan of retinal neurons. (After Cajal.) From Gray's Anatomy. 



terminates in the outer molecular layer by a branched extremity, which 

 is in relationship with the dendritic arborisation of a single cone bipolar 

 of the inner nuclear layer. 



(4) and (5) Most of the nuclei of the inner nuclear layer belong to 

 bipolar nerve cells, one fine process from the nucleus passing into the 

 outer molecular layer, the other towards the inner surface of the retina. 

 The outer process ends in a dendritic arborisation in relation either 

 with the knobs of several rod neurons (rod bipolars), or with the 

 terminal branching of a cone neuron (cone bipolars). The inner process 

 of a rod bipolar arborises about the cy ton of a cell in the ganglionic 



