E. W. BERGER ON THE CUBOMEDUS^E. 55 



quite evident how Schewiakoff should have interpreted the parts of 

 the long pigment cells in the vitreous body as conical pigmented caps 

 placed opposite his supporting cells (long pigment cells). 



Finally, since Schewiakoff had only twelve marginal bodies to 

 study, and since this tissue is difficult to preserve properly, I do not 

 believe that I am doing Schewiakoff any injustice by explaining away 

 his results as I have done. This fact remains, that Conant and 

 myself agree in all points in which we differ from Schewiakoff. 



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 trans- 

 verse 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 



