280 THE RETINA, BY MAX SCHULTZE. 



a layer of flat cells of remarkably large superficial area. These 

 cells, which anastomose by means of their processes, and thus 

 form a fenestrated membrane, he considers to be at the same time 

 in connection with the fibres of the rods and cones ; the conical 

 terminal enlargements of the latter being continuous with the 

 substance of the cells, or of their processes. On the other hand, 

 the radial supporting fibres which terminate at the limitans 

 interna, end in this fenestrated membrane, and never reach the 

 limitans externa. The holes of the membrana fenestrata are 

 occupied by peculiarly formed internal granules, which, accord- 

 ing to Krause, are the terminal cells of the optic fibres, with 

 which, therefore, the rods and cones are not continuous, since 

 these pass by means of their fibres into the fenestrated mem- 

 brane formed by the connective tissue. I am unable to bring 

 the results of my researches into harmony with these views. 



Lastly, the bloodvessels of the retina, which in Man are dis- 

 tributed through all the inner layers, as far as to the external 

 granulated layers throughout the whole extent of the retina, 

 with the exception of the fovea centralis, are to be included 

 amongst the connective tissue. The connection of their exter- 

 nal walls with the reticular connecting substance resembles 

 that observed in the lymphatic and lymphoid glands. Peri- 

 vascular lymphatic passages are, as His supposed,* probably 

 here present. The course of the vessels is elsewhere given. 



4. MACULA LUTEA AND FOVEA CENTRALIS. 



The elementary parts of the retina that have now been 

 described undergo essential modification in their form and 

 arrangement at the macula lutea and fovea centralis in Man 

 and Quadrumana. Nearly in the axis of vision, and at some 

 distance to the side of the optic-nerve entrance, an intensely 

 yellow pigment is deposited between the elements of the differ- 

 ent layers, with the exception of those of the bacillar and 

 external granule layers. The centre of the yellow spot is de- 

 pressed on the surface looking towards the vitreous, to form the 



* Verhandlungen der natur. Gesellschaft. zu Basel, Band iv., Heft ii., 

 p. 256. 



