NERVOUS CONSTITUENTS OF THE RETINA. 235 



Those of the supporting fibres, which are far less numerous 

 than the others, will be subsequently described ; whilst those 

 which are introduced in the course of the nervous radial fibres, 

 and which, in consequence of the large number of these last, are 

 arranged in several superimposed layers, resemble small bipolar 

 ganglion cells. But the quantity of their very finely granu- 

 lated substance is small, and the nucleus is therefore relatively 

 larger than in the case of the true ganglion cells ; the nucleolus 

 is very apparent in the homogeneous nucleus, but is again rela- 



Fig. 347. 



Fig. 347. Internal granules of the retina of Man. Magnified 800 

 diameters. 



tively smaller than in the true ganglion cells. Of the two pro- 

 cesses possessed by the inner granules, and which represent the 

 nervous radial fibres, those that are peripherically directed, as 

 described by Merkel,* from the vicinity of the macula lutea, are 

 usually thicker than the central one. In animals also the inner 

 granules appear to have usually two processes,! though it is 

 only by a happy accident they can be clearly isolated, and we are 

 therefore still far from having an exact knowledge of the ner- 

 vous inner granules and their processes in various regions of the 

 retina, either of Man or of animals. A few inquirers, as Ritter, J 

 have described more than two processes. Great variations 

 occur amongst the inner granules. II. Miiller states that in 



* Loc. cit., p. 11. 



t M. Schultze, Archiv. fiir Mik. Anat., Taf. xiv., fig. 96, from the Cat. 

 Hasse, loc. cit., p. 257. 

 I Wallfischauge, p. 37. 



