292 THE RETINA, BY MAX SCHULTZE. 



bluish-black colour after long maceration ; and lastly, in the 

 rough prickly surface, and the mode of ending at the vitreous. 



It is maintained by various authors that the cones of the 

 human retina continuously diminish in number in relation to 

 the rods from the macula lutea to the ora serrata. This, how- 

 ever, is not correct, as I* have already shown. The relative 

 distribution of the rods and cones remains unaltered from a 

 certain line surrounding the yellow spot to the ora serrata, so 

 that three or four rods are always interposed in the direct line 

 between two cones. At the ora serrata the number of the rods 

 suddenly diminishes, and empty spaces occur between the 

 cones. These last, which appear to increase in number, resem- 

 ble, in a surface view, irregularly circumscribed circles, lose 

 their lustre, and ultimately disappear in the tissue of the pars 

 ciliaris. As was stated by H. Mliller, the height of the rods 

 and cones is less near the ora serrata than in the fundus of the 

 eye or near the equator.t Merkel made similar observations 

 in Man, the Ox, Fowl, and Pike. 



The condition which Iwanoff and I have named oedema of 

 the retina, associated with atrophy of the nerve tissue at the 

 ora serrata, and to which the latter has recently devoted an ex- 

 tended essay, j: presents a very remarkable departure from the 

 normal state. According to Merkel and Iwanoff, it especially 

 occurs in elderly people, consequently may be considered as a 

 senile metamorphosis, || being characterised by the formation 

 of spaces filled with serous fluid, which, intercommunicating 

 with each other, can detach the retina to a not inconsiderable 

 extent, and lead to atrophy of the nerve tissue at the points 

 in question. The radial supporting fibres, however, become 



* A rchiv fur Mikroskop. Anatomie, Band ii., p. 225, Taf. xii., figs. 3, 4. 



t See Max Schultze, Archiv fur Mikroskop. Anatomie, Band v., Taf. 

 xxii., fig. 5, taken from the anterior border; fig. 14, from the neigh- 

 bourhood of the equator ; and fig. 11, from the yellow spot of Man. 



t Grafe, Archiv fur Ophthalmologie, Band xv., Heft, ii., p. 88, 1869. 



Macula lutea, etc., p. 17. 



|| Iwanoff, who observed a large number of these cases, saw the oedema 

 in only six amongst fifty eyes of adults between twenty and forty years of 

 age ; on the other hand, it was present twenty-six times in forty-eight eyes 

 of adults between fifty and eighty years of age. 



