To Conant belongs the credit of having first demonstrated the prismatic structure of the vitreous body, and he also regarded the prisms as a part of the retinal cells. H. V. Wilson[15, 8b] suggested, however, some years prior to Conant, that the vitreous body might be of a prismatic structure. Conant had evidence also of both the prism and pyramid fibers, as is well shown in his figures of transverse sections but he found his evidence too meager to make any very definite statements. Indeed, Conant concludes that there are three kinds of fibers in the vitreous body and complains of finding but two kinds of cells in the so-called retina (pigmented and nuclear zones) to which to refer them. He saw the pyramids with their axial fibers as lighter areas in transverse sections of the vitreous body (his Figs. 64 and 68, and my Figs. 1, 4 and 7), but suggests that they may be the same as the long pigment cells, the cells having only to project themselves or their pigment in order to become long pigment cells. This suggested to him to preserve material both in the light and in the dark. I do not think Conant’s supposition to be a fact, for I find the pyramids in specimens preserved in the light as well as in the dark. It is, of course, possible that the pyramid cells are in a stage of structural transition to the long pigment cells, for, besides their pigmentation, they also have like nuclei. Furthermore, I held for a long time with Conant that there may be only two kinds of cells in the retina, but I soon found the pyramids so definitely shown as to leave no doubt but that they represented a third kind of cell. For me it remained to first definitely see all the fibers in the vitreous body as also the pyramids in sagittal sections. Conant describes the long pigment cells with their fibers extending between the prisms of the vitreous body quite as I have described, and in this my work is only confirmatory of his. Conant does not, however, describe the several centrad processes of these cells, nor is he clear that their distad processes extend to the lens, though he speaks of fibers within the capsule.