26 H. M. BERNARD. 



attention to the phenomenon is Borysiekiewitz.^ This writer 

 recorded two evidences of migration (" Ortswecbsel ") of 

 nuclei in the human retina. Nuclei wandered outwards — (1) 

 from the outer nuclear layer into the basal limbs of the cones, 

 an observation which was not new ; and (2) from the middle 

 nuclear layer through the outer reticular layer. I then added 

 that in this latter case " it was the characters of the migrated 

 nuclei, exactly like those of the layer they had left, and not 

 at all like those of the layer into which they had moved, 

 which convinced him that migration must have taken place," 

 The similarity of these nuclei had been so often noticed by 

 myself as a convincing proof that the nuclei embedded in the 

 outer reticular layer were passing through it, to become 

 transformed into rod nuclei, that after reading Borysiekiewitz's 

 two treatises, and finding that he had also noticed the 

 migration; I inadvertently attributed to him an observation 

 which, however, he does not make. He only indirectly 

 indicates it in his quotation from Dogiel, who recognised a 

 layer of " subepithelial nerve-cells " in the outer nuclear 

 layer, i. e. a layer of " cells " exactly similar to those on the 

 other side of the outer reticular layer, called by Dogiel " 

 " the bipolar cells of the ganglion retinae." Borysiekiewitz 

 remarks that such cells are probably merely his migrated 

 nuclei,^ but rightly adds that they do not form a "layer." 



Borysiekiewitz was himself convinced of the migration of 

 the nuclei by finding a tract (1. c, p. 37) in one of his pre- 

 parations in which the middle nuclear layer changed from two 

 rows into one row and then back again ; but where it was in 

 a single row, the missing nuclei were visible either in, or on 

 the outer side of, the reticular layer (for a parallel case see 

 fig. 19, with description). This valuable observation shows 



1 'Weitere Untersuchungen iibcr den feiueren Bau der Nelzliaut,' Wien, 

 1894. 



2 'Archiv f. niikro. Aiiat.,' 38, p. 317. 



3 Borysiekiewitz uses the word " Korn," which docs not exactly mean 

 nucleus, l)ul, in this connection it is practically the nuclei alone about which 

 unvthing can be deiiuilely stated. The point will be dealt with in my next 

 paper. 



