Chap, xxxix.] THE RETINA. 311 



fibres retain their medullary sheath in the retina 

 (Bowman)'. The nerve-fibres remain grouped in 

 bundles in the retina, and even form plexuses. For 

 obvious reasons, the number of nerve-fibres in the 

 nerve-fibre layer diminishes towards the ora serrata. 



438. (3) The layer of ganglion cells. There 

 is one stratum of these cells only, except in the 

 macula lutea, where they form several strata. Each 

 cell is multipolar, and possessed of a large nucleus. 

 One process is directed inwards and becomes con- 

 nected with a fibre of the nerve-fibre layer. Several 

 processes pass from the opposite side of the cell, and 

 enter the next outer layer, i.e., the inner molecular 

 layer. 



According to Max Schultze and others, they break 

 up there into a reticulum of fibrils which is part of 

 this molecular layer ; but according to Retzius, Mans, 

 and Schwalbe, they simply pass through the inner 

 molecular layer. 



The ganglion cells are separated from one another 

 by the radial fibres of Miiller. 



439. (4) The inner molecular layer is a 

 fine and dense reticulum of fibrils, with a small 

 amount of granular matter between. The fibrils are 

 connected with lateral branchlets of the radial fibres 

 of Miiller. This layer is, on account of its thickness, 

 a conspicuous part of the retina. In lower vertebrates 

 it appears stratified. 



440. (5) The inner nuclear layer contains in 

 a honeycombed matrix of a hyaline stroma numerous 

 nuclei, in two, three, or four layers. In the am- 

 phibian retina these form a larger number of layers. 

 Some oblong nuclei of this layer belong, as has been 

 mentioned above, to the radial fibres of Miiller. 

 Next to the molecular layer are small nuclei belonging 

 to flattened branched cells (Vintschgau). But the 

 great majority of the nuclei of this layer are slightly 



