3 6 



HISTOLOGY. 



bases of the visual cells (Fig. 412,+). Toward the inner surface of the 

 inner nuclear layer there are large ganglion cells which send branched 

 processes into the inner reticular layer. Neuraxons of these "amakrine 

 cells" have not been found. Some fibers extending out from the brain 

 through the optic nerve terminate in free endings within the inner nuclear 

 layer. 



The inner reticular layer consists of a very fine supporting network, 

 lodging the processes of the bipolar and amakrine cells, together with the 

 dendrites of large multipolar cells of the ganglion layer beneath. 



. The ganglion cell layer or ganglion of the optic nerve consists of a 

 single layer of large multipolar cells containing Nissl bodies. Giant forms 



aW Fiber basket. 



Nucleated part of the 

 fiber. 



^. Basal pyramid. 



Precipitate. 



FIG. 413. GOLGI PREPARATION OF RADIAL FIBERS IN A THICK SECTION OP THE HUMAN RETINA. 

 The fine processes of the fibers in the outer nuclear layer appear as a compact mass. X 360. 



occur at quite regular intervals. "Twin cells" have been described as 

 joined by a short bridge, only one of the pair having a neuraxon. The 

 branched dendrites of these ganglion cells extend into the inner reticular 

 layer; their neuraxons pass toward the papilla of the optic nerve and 

 except for the internal limiting membrane which covers them, they form 

 the innermost layer of the retina. Collaterals have been detected returning 

 from this nerve fiber layer to branch about the cell bodies of the ganglion 

 layer. The nerve fiber layer also contains the centrifugal fibers which 

 terminate in the inner nuclear layer. The fibers are all non-medullated. 

 Summary. The elaborate subdivision of the retina into eleven layers 

 should not be allowed to obscure the essential features, namely, that it 



