228 THE RETINA, BY MAX SCHULTZE. 



condensations of the non-medullated fibres ; their substance is firmer 

 and more lustrous than the healthy axis-cylinder, and is capable of 

 resisting decomposition for a longer period. 



Section of the optic nerve in the orbit in animals is followed by 

 atrophy of the nerve-fibre layer (Lehmann), and this, according to 

 Krause, is preceded by a deposit of fat molecules in the transparent 

 pale fibres, which form of degeneration extends to the elements of the 

 following layer, to wit, the ganglion-cell layer. 



On the outer side of the nerve-fibre layer, and extending 

 over the greatest part of the retina, is a simple layer of nerve, 

 cells or corpuscles, separated by interspaces of various size, 

 which is designated the layer of ganglion cells. Near the 

 macula lutea of Man, two or three such cells are superimposed 

 upon one another, whilst at the yellow spot itself, with sup- 

 pression of the nerve-fibre layer, the ganglion cells come to be 

 arranged in a single layer. The size of these cells varies to 

 an extraordinary extent in the same retina; so that sir all ones 

 not exceeding fifteen micromillimeters are found in close 

 proximity with others of double that size or more. All have 

 the peculiar finely granular appearance of the cell substance 

 presented by the nerve corpuscles of the ganglia of the central 

 organs, and are for the most part without yellow pigment,* 

 which it is well known often occurs in other nerve cells ; they 

 contain a relatively large homogeneous transparent nucleus, 

 with the large nucleoli that all ganglion cells possess, and in the 

 interior of this again, is here and there a small vesicle or 

 granule. Notwithstanding the difficulty of isolating perfect 

 specimens of these cells, a large number of observations have 

 been made on the long and branched processes, which, like the 

 ganglion celL of the nervous centres, they give off. A particular 

 condition of maceration of the retina, not easily hit upon, appears 

 to be requisite in order to permit the isolation of these cells to 

 be satisfactorily accomplished; at least, we can only thus 

 explain the circumstance that the best preserved processes 

 of these cells that have hitherto been observed, were obtained 



* According to Corti, the ganglion cells of the retina of the Elephant 

 have a yellowish or yellowish-brown colour. 



