The pigmented zone of the pyramid cells, in heavily pigmented series, is filled throughout with dark-brown pigment granules, and is quite like that of the prism cells (Figs. 4, 7). In transverse sections, however, through the most distal part of the pigmented zone, of unpigmented series (Fig. 2), lighter areas with central dots could occasionally be demonstrated, which areas are the pyramid cells. In Fig. 2, the more definite polygonal outline as well as the lighter shade of these areas was a distinguishing feature. The difference in shade was not wholly due to a difference in pigmentation but to a structural difference. The nuclei of these cells are usually a little larger than those of the prism cells and are filled with a finer and less dense network (Figs. 4 and 7, npyr), in consequence of which they present a lighter appearance in sections when examined with a high power. It will be seen in the figures (4, 7) with what regularity these lighter nuclei lie opposite the pyramids. Some few exceptions occur. These are probably due to the fact that a nucleus or pyramid was not differentiated by the technique. If this opposition between the pyramids and the lighter nuclei were all, I believe it would be sufficient evidence for associating these lighter nuclei with the pyramid cells.[f] (c) The _long pigment cells_ are about as numerous as the pyramid cells. In these cells, as in the prism and pyramid cells, three regions can be distinguished: the region of the nucleus, a pigmented region (the distal half of which extends between elements of the vitreous body), and a distal rod-like portion, or fiber, which is continued between the prisms into the capsule of the lens (Figs. 4, 7, 9). The pigmented portion is about twice the length of that described for the other cells, and also often of greater diameter, so that in transverse sections (Figs. 1, 2, 3) these cell-areas are larger than those of the other cells. As nearly as I could determine, these cells are pigmented just like the other retinal cells described. In quite unpigmented series, however, they often contain more pigment than the other cells do (Fig. 2). Distally, the pigmented part becomes narrowed to a strong pigmentless fiber (Figs. 3, 4, 7). This fiber stains quite dark with iron-hæmatoxylin and appears homogeneous. It passes between the prisms into the capsule, where it usually bends in a direction toward the margin of the capsule (Fig. 7) and passes diagonally across this to the lens. In sections, a space is often seen about these fibers in the vitreous body, which I regard as a shrinkage space (Figs. 3, 4), since it is not evident in all series (Fig. 1). In Fig. 7, I have assumed that these spaces are due to shrinkage and have not indicated them. Also, in this same figure I have assumed that the spiral appearance of the fibers (Fig. 4) is due to a shortening of the prisms during fixation, and have drawn them straight. At the lens these fibers seem to end.