588 THE EYE 



row zone at the inner margin of this nuclear layer. These are 

 large stellate cells whose dendritic processes extend into the inner 

 reticular layer and take part in the formation of the dense felt- 

 work of which that layer consists. The course of the axis cylinders 

 of these cells is still a matter of some doubt. Ramon y Cajal, be- 

 lieving these cells to possess no neuraxis, designated them "amac- 

 rine cells" and subdivided them according as their dendrites were 



FIG. 432. Two AMACRINK CELLS OB SPONGIOBLASTS FROM A TRANSECTION OF THE 



RETINA OF A CALF. 



Golgi's stain, x 260. (After Kolliker.) 



distributed in either one of several horizontal planes (the number 

 varying in diiferent species) or diffusely throughout the inner 

 reticular layer. 



Some of the amacrine cells, however, send a neuraxis in a hori- 

 zontal direction to the inner reticular layer, and are also in relation 

 with the terminal arborizations of centrifugal nerve fibres which 

 enter from the nerve fibre layer. These have been regarded by 

 some observers as "dislocated nerve cells" of the ganglion cell 

 layer; Cajal named them "association amacrines" 



8. The inner reticular layer (inner molecular layer, inner plexi- 

 form layer, neurospongium) is a densely tangled network of nerve- 

 cell processes, a neurospongium. To these are added a much 

 branched portion of Miiller's fibres, which form the chief support- 

 ing tissue of this layer. The cell processes entering into this for- 

 mation are derived from the cells of the inner nuclear and ganglion 

 cell layers, and it is here that the processes of these cells interlace 

 so closely as to permit the transmission of impulses from the one 

 neurone to the other. Their terminal arborizations are, for the 

 most part, disposed in horizontal planes, though a few spread 

 throughout the entire thickness of the reticular layer. 



9. The ganglion cell layer (ganglion nervi optici, inner gangli- 

 onic layer, layer of large nerve celh) is of variable thickness. Its 

 greatest depth is in the region of the macula lutea, where it con- 

 sists of five or six superposed ganglion cells. Toward the equator 

 of the eye it becomes progressively thinner, until near the ora ser- 

 rata its single layer of cells only forms an incomplete stratum. 



