586 THE EYE 



thickness, contains only rod nuclei. The former,, with occasional 

 exceptions (Stohr *), are situated in only one relatively narrow 

 plane ; the latter are distributed at various levels, though they 

 occur more abundantly in the mid-region of the nuclear layer. In 

 addition to portions of Miillers fibres which serve for the support 

 of the nucleated elements, this layer contains the terminal filaments 

 of the distal processes of some of the small bipolar nerve cells of 

 the inner nuclear layer. 



5. The fibre layer of Henle is formed by that portion of the 

 cone fibres which is internal to the layer of rod nuclei. It is a 

 thin layer and only acquires importance in the neighborhood of the 

 macula lutea, where the cones are most abundant. In this portion 

 of the retina it is easily distinguished from the outer reticular layer 

 by the somewhat radial disposition of its fibres, the fibres of the 

 reticular layer having an irregularly meridional direction. 



6. The outer reticular layer (outer molecular layer) presents a 

 dense tangle of neural tissues consisting of supporting neuroglia 

 fibres and interlacing processes from the horizontal and bipolar 

 nerve cells of the inner nuclear layer. Terminal fibrils from this 

 network intermingle in the fibre layer of Henle with terminal fibrils 

 from the cone feet ; more externally they are in intimate relation 

 with the end knobs of the rod fibres. This arrangement permits 

 the transmission of stimuli from the neuro-epithelium to the retinal 

 ganglion. 



7. The inner nuclear layer (inner granular layer, ganglion 

 retince, outer ganglionic layer) contains a mass of nerve cells, to- 

 gether with the nucleated portion of the fibre cells of Miiller. The 

 nerve cells may be described as corresponding to one of three types, 

 which, from the plane in which they are distributed may be termed 

 the outer, middle, and inner. 



The outer nerve cells (horizontal cells, basal cells) possess pyram- 

 idal, stellate, or flattened cell bodies whose dendrites are distrib- 

 uted to the horizontal plexus of the outer reticular layer. These 

 cells vary in size ; the dendritic or distal processes of the larger 

 cells on reaching Henle's layer are in relation with the terminal 

 fibrils of the cone feet ; those from the smaller nerve cells are in 

 relation with the terminal knobs of the rod fibres. The axis cylin- 

 ders or central processes from all these cells after traveling hori- 

 zontally viz., in a plane parallel to the layers of the retina for a 

 greater or less distance, turn inward and pass to the inner reticular 

 * Verhandl. d. phys. med. Gesellsch., Wiirzburg, 1887. 



