SEA-FISHERIES LABORATORY. 435 
the basal end the nucleus causes a rapid increase in the 
framietera(fie. 30, H.C.n., and fig. 29, H.C.n.). The 
nuclei of the rod cells are to be found in longitudinal 
sections through the eye, im a cluster not far from the 
sides of the retina (fig. 29, KR. C.n.) and before the point is 
reached where the cells curve almost at right angles to 
form the basal portions, which like a series of columns he 
with their long axes in a proximal-distal direction. 
Another series of nuclei is generally conspicuous 
(fig. 380, C.2.), but, as first shown by Patten (35), these do 
not beione to the rod cells, but belong to cells lying 
between them (inner interstitial cells). The rod cells all 
terminate at the same level, or rather pass directly into 
their continuations—the rods. At the line of junction of 
these two elements there are traces of a delicate membrane 
extending across the retina, called by Schreiner (37) the 
outer sieve membrane (fig. 30, S.m.o.). This is per- 
forated by the rods, and does not, as Patten stated 
(terminal membrane), separate the rod cells from the rods, 
that is, form the actual base of the rod cells. Hach rod 
cell is connected with a rod, the one being a continuation 
of the other, the line of division being marked by 
the outer sieve membrane outside the cell, and internally 
by a difference in cell structure. Like Schreiner, I have 
seen no vacuole described by Patten as existing at the 
base of the rod cells. 
The Rods (fig. 30, 2.) are difficult to preserve in good 
condition, but absolute alcohol sublimate gives good 
results, and- sometimes Flemming, though with large 
Pecten maaimus eyes the latter probabiy does not 
penetrate quickly enough. They are cone-shaped bodies, 
longest in the centre of the retina and decreasing slightly 
in size towards the periphery. The basal portions of the 
rods are separated from each other by, and rest on, a 
