STUDIES IN THE liETINA. 61 



Usually comparatively thin as they leave the inner reticular 

 layer, they expand into a conical arrangement of strands or 

 membranes until they look in some sections like an arcade of 

 expanding columns supporting the internal limiting mem- 

 brane with its subjacent reticulum. Under the arches of 

 this arcade are found the strands of the optic nerve, and the 

 so-called " ganglionic cells." My faith in the sustentacular 

 character of the " Miiller's fibres " was first shaken by finding 

 that in many of my preparations the majority of these 

 columns arise from the edge of, or from various depths 

 within the inner reticular layer itself, and that those which 

 did so did not apparently differ from those which came 

 through the inner reticular layer from the outer layers. It is 

 quite apparent that when they arise from the edge of the 

 inner reticular layer, they are in a position to collect and 

 carry away matter from that layer (figs. 20, h, 21, 24, a, 

 26, h, 27). It is common also to find them arising in one of 

 the darker zones above referred to, and when once the 

 suggestion is made that they are, as it were, draining the 

 inner reticular layer, a flood of light is thrown upon all 

 their various shapes, for the typical arcade form I have 

 described, though frequently found, is not invariable. 

 In my preparations of the retina of a large cod, for instance, 

 the typical expanding columns are somewhat rare, so 

 that the matter, not carried away fast enough, clogs any 

 strands or membranes running tangentially ; see fig. 21, in 

 which it coats the strands [n.s.) supporting the nerves. 



Solid accumulations of this matter are, however, not often 

 found in the nerve-fibre layer, although the clotting of the 

 nerve and other strands which partly occupy the layer may 

 be very dense (see fig. 28, h, from an old rat). Something 

 more like solid accumulations are found in certain old eyes ; 

 e. g. figs. 26, a, h, and 28, a, show the absorbed matter 

 accumulating within the conical expansions of the ''Miillei-'s 

 fibres," sometimes causing them to change their forms and 

 become nearly bell-shaped — the trumpet shapes shown in 

 fig. 26, 6, are apparently due to distortion of the sections. 



