58 H. M. BERNARD. 



radial^ e. g. "the rod and cone fibres/^ hence accumulations 

 of amorphous matter seldom take place in this layer. On 

 reaching the outer reticular layer there occurs^ as described, 

 some temporary obstruction, the exact nature of which we 

 have not attempted here to unravel. Through this reticular 

 layer, however, the matter escapes. In young eyes with a 

 plentiful cytoplasmic reticulum supporting the rows of nuclei, 

 radial strands can be found in abundance to carry the matter 

 through the middle layer to the inner reticular layer; but in 

 older eyes, when the nuclei of the middle layer have been 

 largely used up and the cytoplasmic reticulum is so reduced 

 that but few radially disposed strands can be found, the re- 

 fractive matter tends to accumulate often in large quantities 

 {m.n. of the figures). In fig. 20, h (bleuny), it is seen in small 

 irregular patches; in fig. 24, a (trout), in thick tangential 

 strands just above the outer reticular layer; in others, 

 again, in immense taugentially arranged sheets. In fig. 2o, 

 a and b (plaice), the accumulations are near the outer 

 reticular layer; in fig. 21 (cod) near the inner reticular 

 layer. Many more figures might have been given, but 

 these must suflSce. Fig. 23, a, which was from a very 

 large old plaice,^ should be compared with fig. 22, a, 

 b, c, which are from a young plaice, six inches long. In 

 the least used-up part of the retina (e) no traces of these 

 accumulations can be seen ; in b they are beginning ; in a they 

 are already of considerable size, but in the very old fish they 

 are enormous, and occur over most of the retinas. Of the few 

 traces which I have so far seen of accumulations of matter 

 in the retinae of mammals one is shown in fig. 30, where a thick 

 strand runs along on the inner side of the outer reticular 

 layer of a mouse which had been exposed to the light of an 

 arc lamp. As it tapered away it gave off typical " Miillei's 

 fibres" in the way figured (see also p. 37 and fig. 20). 



Before going on to the inner reticular layer, one word as to 

 the supposed nuclei of the " Muller's fibres." These arc nothing 



' Speciall^f selected for these researches by my friend the late Mr. Martin 

 Woodward, while temporarily associated with the Irish i'islierics. 



