. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Heteropygii. 142 BLIND VERTEBRATES AND TEELR EYES. in many sections of Chologastcr and the method of the closing of the pupil in Typh- lomolge is as I have suggested. The Nuclear Layers. — Within the pigment and cone layer lies a nuclear layer made up of about four series of cells (3 to 7 in figs. 50, 54 e). The nuclei reach from to jx in diameter. Rarely I have succeeded in staining the smaller nuclei different from the larger. They are, in such cases, more refringent, the large nuclei being granular. The
. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Heteropygii. 142 BLIND VERTEBRATES AND TEELR EYES. in many sections of Chologastcr and the method of the closing of the pupil in Typh- lomolge is as I have suggested. The Nuclear Layers. — Within the pigment and cone layer lies a nuclear layer made up of about four series of cells (3 to 7 in figs. 50, 54 e). The nuclei reach from to jx in diameter. Rarely I have succeeded in staining the smaller nuclei different from the larger. They are, in such cases, more refringent, the large nuclei being granular. The larger nuclei may be the spongioblasts. In a young indi- vidual this difference was well marked. Here the smaller cells were confined to the proximal part of the eye (fig. 53). A separation of the nuclear layer into an . Fig. S4- From an Individual 35 mm. long killed in Perenyi's Fluid and stained with Mayer's Hsmalum. (a) Outer Nuclear Layer in Center, Choroidal infolding on Left. Lower Part of figure passes through Choroidal Fissure Area and Pigment Cells are here undifferentiated, quite different from those of the Dorsal Part of Same Section. (6) Further Forward and shows Strands of Optic Nerve (». op.) and Elongated Nuclei of Inner Layer of Iris irregularly arranged (»/. /.). Choroid and Sclera can not be separated from each other except where Latter is differential as Cartilage, in front of Eye. (c,d) Surface and Deeper Focus of Section passing through Iris and Central Ganglionic Cells. In fig. d Irideal Structure with Elongated Inner Nuclei is well shown. (e) Passes near Center of Eye. Choroidal Fissure Epithelium seen below and Irregular Mass of Section through Elongated Irideal cells (nl. I.). (/) Passes through Optic Nerve and Pupil of Same Eve as fig. e. Figs, a to d are from Left Eye, e and / from Right Eye. All under Lenses 2 mm. and 4. inner and outer with an intervening outer reticular layer I have noticed but once. In this eye a slight separating space w
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