350 MICROSCOPIC ANATOMY OF THE ORGANS. 



cells (e-i) are associated, by means of the processes which are 

 sent into the outer reticular layer, with the broad conical ends 

 of the cone fibres. The inner processes, on the contrary, enter 

 the inner reticular layer, where they come into contact at 

 various levels with the branched protoplasmic processes of 

 the ganglion cells. 



Besides these cells, we find at the inner border of this layer, 

 cells which are known as spongioblasts (W. Miiller) or para- 

 rctlcalar cells (Kallius). The processes of these cells end in 

 the inner reticular layer. With these cells must be classified, 

 according to Ramon y Cajal, those in which no axis-cylinder 

 process is to be seen (amakrine cells, a- and 3-). Some of 

 these give off end arborizations only at certain levels (a-e, cells 

 in which the dendrites are arranged in layers). Others, on 

 the contrary, send their processes diffusely through the whole 

 thickness of the inner reticular layer ( S>). 



Besides the amakrine cells, we find at this level, in certain 

 animals, cells giving off axones which pass over into optic 

 nerve fibres. Finally, there are cells (m, /) which possess 

 one or more main processes spreading out on the outer surface 

 of the inner reticular layer. They resemble the so-called 

 horizontal cells (Ramon y Cajal), which lie in the outer 

 part of the outer ganglionic layer at the boundary of the outer 

 reticular substance. These cells owe their name to the fact that 

 their long axis lies parallel to the surface of the retina. They 

 are ganglion cells whose bodies give off numerous short den- 

 drites, branching abundantly in the outer reticular layer, and 

 also a long, fine, horizontal axis-cylinder process, which breaks 

 up at the end into numerous branches. Two kinds of these 

 cells can be distinguished: the outer smaller cells (m), whose 

 axis-cylinder processes come in contact by end arborizations 

 with the ends of the cone fibres; and the inner large cells (/), 

 whose long processes are connected with the end bulbs of the 

 rod fibres. These cells join together distant parts of the 

 retina. 



We find also in this region cells (K) which send out 

 processes which end above in the outer and below in the 



