54 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGEAPHS. 



extend to the lens as described. The prisms and pyramids are, 

 further, the distal continuations of cells whose pigmented and 

 nuclear parts lie in the so-called retina, but which, together with the 

 vitreous body, I have named the retina proper. Conant has so sum- 

 marily disposed of Schewiakoff s distinction between retinal cells based 

 on pigmentation and location of nuclei, that I need not say more. 

 Schewiakoff 's Fig. 18 corresponds to my Fig. 1. In this figure he 

 shows the vitreous body as homogeneous with pigmented areas 

 (my long pigment cells) and with spaces with his visual rods. It is 

 quite evident that his spaces with the visual rods correspond to 

 my lighter areas with central dots ; i. e. my pyramids of the 

 vitreous body are the same as the spaces shown in his Fig. 18. 

 It is quite evident that Schewiakoff mistook the lighter areas for 

 spaces. That they are not spaces can readily be seen by comparing 

 them with real spaces. It is, of course, possible, too, that the reagents 

 had dissolved the pyramids, leaving only the axial fibers with a little 

 pyramid substance about them, and that this is what Schewiakoff 

 saw. I often found small circular spaces in the centers of the 

 pyramid areas, as also in the prism areas (Fig. 3), which might be 

 taken for hyaline visual rods, fibers, in transverse section, but in 

 such spaces I could usually see a small dot to one side of the space 

 that I take to be the rod (fiber) proper. Fig. 14 also shows such 

 small circular spaces that have very much the semblance of. hyaline 

 rods. This figure is a transverse section of the vitreous body of the 

 proximal complex eye, in which no long pigment cells or pyramid 

 cells are present, but it serves well to illustrate the point. The above 

 explanation also accounts for the large size of the visual rods (fibers) 

 in Schewiakoff's figures. That the fibers of the pyramid cells (visual 

 rods of Schewiakoff) do not extend to the lens is quite evident in my 

 Figs. 4 and 7. 



Again, since the long pigment cells are often not seen to termi- 

 nate in a fiber, but a part of the fiber can often be seen in the 

 distal part of the vitreous body and in the capsule, it will be quite 

 readily seen how Schewiakoff should associate his visual rods, or 

 fibers, with these distal parts of the fibers of the long pigment cells 

 and suppose his visual rods to extend to the lens. 



Again, since the long pigment cells sometimes cannot be seen to 

 terminate distally in a fiber, while the vitreous body at the same 

 time may be broken away from the pigmented zone (Fig. 4), it is 



