E. W. BERGER ON THE CUBOMEDUSA. 63 
quite in the angle between the proximal complex eye and the group 
of network cells in the upper part of the club. In this series I 
could very definitely trace the distal fibers of the retinal cells 
centrad, past the nucleus and into the subretinal nerve-tissue. 
These fibers could be so easily followed that no doubt can exist as 
to the fact noted. It thus appears that the axial fibers just 
described pass centrad through the cells and are continued as nerve 
fibers. On the evidence of such sections as Fig. 16 I have indicated 
these fibers as extending centrad through their cells. The lumen of 
the simple eyes is filled with a homogeneous vitreous — secretion. 
This is often incomplete in some parts; occasionally the secretion 
shows a formation of globules, but all this I believe to be due to 
the action of reagents. Indeed, I have found simple eyes in which 
hardly any secretion was present, while others showed an almost 
completely filled cavity. In that portion of the vitreous secretion 
just outside the mouth of the distal eyes I occasionally found numbers 
of very darkly staining granules. I suspect that these are either 
bacterial or algal organisms. 
As already noted, Claus and Schewiakoff describe two kinds of 
cells for the retinas of these eyes which neither Conant nor myself 
can demonstrate. Further, I believe I have shown that only one kind 
exists. If any doubt should still exist, a section like Fig. 25 (which 
is from the epithelium of the club, but similar smaller areas with 
central dots could often be demonstrated in transverse sections of the 
retinal cells of the simple eyes) I believe should be convincing. 
Schewiakoff further describes flagella for the retinal cells (his visual 
cells) of the simple eyes quite as I have described them for all the 
cells. The pigmentation that Schewiakoff mentions as occurring in 
the secretions within the lumina of these eyes I believe to have 
been dissolved in from the pigmented zones. I find no definite pig- 
mentation in these vitreous secretions. These secretions are evidently 
products of the retinal cells and have been so regarded by former 
observers. 
Lithocyst and Concretion—The cavity filled by the concretion is 
lined in places by a single layer of cells, two of which are shown in 
Fig. 7. This fact has been noted by both H. V. Wilson and Conant. 
Such cells are evidently remnants of the cells that formed the con- 
cretion. The supporting lamella completely surrounds the cavity of 
the concretion. 
