THE EYE OP PEGTEN. 83 



remarkable retina, innervated by the proximal branch of the 

 optic nerve. This region is most obvious in sections and is 

 composed of a row of pillar-like rod-cells, bearing rods, with 

 a series of interstitial cells lying between the former and 

 once supposed to be their nuclei. 



The rod-cells (i-etinophorae of Patten) (PI, 7, fig. 13, 

 JR. G.) occupy a very large part of the retina. In very young 

 eyes, however, the distal cells are more prominent and occupy 

 a proportionately much larger part. They are extremely long 

 cells, especially those situated in the centre of the retina. 

 The outer ends, to be found at the periphery of the retina, 

 are attenuated and pass gradually into the nerve-fibres of the 

 proximal branch of the optic nerve (PL 6, fig. 1, 0|j. P."), so 

 that it is impossible to say where one ends and the other 

 begins. From this point they increase in thickness, the first 

 third of their length or more lying almost horizontally under 

 the outer layers of cells, embraced by the processes of the 

 supporting cells. Some little distance from the periphery, 

 not very different for cells from different parts of the retina, 

 each swells rather suddenly round its nucleus (PI. 7, fig. 13, 

 R. 0.11.) y and from this point the thickness remains practically 

 the same to the basal end, though there is a slightly more 

 constricted part below the nucleus. All the rod-cell nuclei 

 are situated in a scattered cluster not far from the edge of 

 the retina, so that the nucleus is nearer the proximal end in 

 rod-cells belonging to the centre of the retina, whilst in the 

 middle or slightly nearer the base of rod-cells from the 

 peripheral regions. 



The distal cylindrical portions of the rod-cells lie parallel 

 with one another, perpendicular to the plane of the retina, 

 and terminate at the same level, forming a well-defined line 

 between them and the layer of rods. This line (PI. 7, fig. 13, 

 S.m.) has been described as the section of a membrane (see 

 table), which extended across the retina and was pierced by 

 the rods (PI. 7, fig. 13, Rod). These are direct continuations 

 of the rod-cells, and rod and rod-cell form together one 

 entity — the product of one cell. Patten described a delicate 



