THE COXXECTIVE-TISSUE FRAMEWORK OF THE RETINA. 275 



granular protoplasm around the nucleus. These nuclei of the 

 radial supporting fibres form the second kind of internal 

 granules mentioned above. The supporting fibres themselves 

 usually traverse the layer of optic-nerve fibres with great re- 

 gularity, in order to take part in the formation of the limitans 

 interna. They are here arranged serially, the direction and 

 fascicular mode of grouping* of the fibres corresponding for 

 the most part with that of the nerve fibres, whilst they are pro- 

 longed into conical flattened enlargements, or after undergoing 

 division, like roots of a tree, are continuous with several such 

 terminal dilatations, f which ultimately coalesce to form a smooth 

 membrane on.the side turned towards the vitreous the frequently 

 mentioned membrana limitans interna. J At many points the 

 connection of the ends of the radial fibres with the membrane 

 is deficient, in which case a fine fibrous plexus occupies the 

 intervals between the truncated cones, and the limitans is per- 

 forated in a filigree-like manner. Such an appearance is pre- 

 sented by surface views of this membrane in Rabbits. At the 

 yellow spot, where the optic fibres no longer form a special 

 layer, and the ganglion cells occupy the inner surface of the 

 retina, even the extremities of the thicker radial fibres fail to 

 join the limitans interna. The radial supporting fibres are in 

 point of fact commonly absent at this very soft portion of the 

 retina ; at the same time the limitans interna is by no means 

 absent, but, on the contrary, is very resistant, and can easily be 

 detached as a separate membrane. As in other parts of the 

 retina, it appears as a denser membranous portion of the sup- 

 porting connective tissue, but becomes detached from them and 

 from the spongy substance between the ganglion cells, the more 

 readily the greater the difference in the consistence of the two. 

 The external surface of the limitans interna presents a very 

 distinctly rough appearance at the yellow spot, owing to the 

 remains of innumerable ruptured fibres, and demonstrates in 

 this way its continuity with the adjoining portions of the con- 

 nective tissue, which is at the same time doubtless very differ- 



* Kolliker, Gewebdehre, 5th Edit., p. 680, fig. 488. 



t M. Schultze, De Eetin. Structura penit. , fig. 3. 



J Schelske in Virchow's Archiv, Band xxviii., p. 482. 



