STUDIES IN THE RETINA. 455 



chromatin globules, and are usually found in young rapidly 

 growing retinas.^ In well-stained preparations it is common 

 to find that, from these bodies, fine threads run down the 

 walls of the outer limb. In one figure of a developed rod 

 this thread was the only one Avhich took the stain (fig. 29, c). 

 In another figure, two staining and rather straggling threads 

 came from one of these bodies, which had apparently been 

 flattened out against the membranous partition between inner 

 and outer limb {6g. 15, a). To this phenomenon, i.e. this 

 membrane acting as a barrier between inner and outer limb, 

 we shall return. 



Even where there are no such bright globules of chroma- 

 tin, the derivation of the reticulum of the outer limb from 

 that of the iniier can be at once seen if we study the figures 

 of the developing cones shown in fig. 29, e — j. These figures 

 are merely a selection, and might be multiplied indefinitely. 

 They show quite clearly that the staining material within the 

 outer limb appears where the thin threads from the inner limb 

 come down on its wall. This fact shows that the striation of 

 the outer limbs of the cones figured by Max Schultze and 

 Hoffmann may exist, not as a complete system as they repre- 

 sented it, but as the first beginnings of the subsequent stria- 

 tion of the rods. 



Unfortunately none of these figures (29) seem to show the 

 true tips of the cones ; still, enough is here seen to demon- 

 strate the point we have immediately in hand. 



Lastly 1 would refer to fig. 2G, which is by no means an 

 uncommon phenomenon. A nucleus is seen passing through 

 the outer reticular layer and about to join the outer nuclear 

 layer (that of the rods and cones). It is preceded by a fluid 

 space, while from it a very delicate reticulum streams out- 

 wards. This I interpret as representing a very early stage 

 in the formation of a rod, being still entirely within the 



' The only other figure I know of whicli shows such a body is one by 

 Hensen (I. c, fig. 7, c), who, as we have seen, came so near discovering tlie 

 structure of tlie rods, having failed apparently for the want of better micro, 

 scopic technique. 



