56 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 
he clear that their distad processes extend to the lens, though he 
speaks of fibers within the capsule. 
(f) What, now, is the function of these three varieties of cells 
of the retina? Schewiakoff regards his visual cells (pyramid cells), 
as the name implies, as having a visual function. That they have 
such it seems reasonable to suppose, since they have an axial fiber 
in their pyramids. If the pyramid cells are visual cells, it appears 
that the prism cells also are such. Indeed, since these are the only 
ones present in the proximal eye and the more numerous ones in the 
distal eye, and like the pyramid cells have an axial fiber in their 
prisms, it seems that they are the visual cells par excellence of the 
Cubomedusan eye. Also, the analogy between the prisms and 
pyramids on the one hand, and the rods and cones of the vertebrate 
eye on the other hand, does not seem to be so far fetched. It may 
be of interest, here, to briefly consider Patten’s theory of color 
vision.”” 
The gist of Patten’s theory is this: In the eyes of certain 
molluscs and arthropods, in the parts of the retinal cells corres- 
ponding to my prisms and pyramids, he not only finds an axial 
fiber (or fibers) but finer fibrils that extend at right angles from 
these axial fibers to the surface of the rods (I shall here, for 
convenience, call the prisms, pyramids, etc., rods) where they probably 
become continuous with other fibrils in the surface of the rods. 
These fibrils from the axial fibers are arranged in superimposed 
planes, and if I understand rightly, an axial fiber with its radiating 
fibrils may be compared to the axial wire with its radiating bristles 
of a brush used for cleaning bottles, provided the bristles of such 
a brush be arranged in superimposed planes. ‘The lateral arrange- 
ment of the fibrils will, of course, be modified according whether 
a rod is circular, hexagonal, square, etc., in transverse section. It 
will also be remembered (p. 49) that Patten describes the retinal 
cells studied by him as composed of twin cells, and he gives the 
name retinophora to a pair. The system of fibers and fibrils in the 
rods he names a retinidium. Centrad the axial fibers are continued 
past the nucleus as a nerve fiber. The fibrils extending laterally in 
superimposed planes from the axial fiber of a rod, Patten supposes 
to be the ones stimulated by the incoming rays of light, the 
retinophora being so arranged that the light rays entering them are 
parallel to the axial fibers or perpendicular to the lateral fibrils of the 
