. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. 124 BLIND VERTEBRATES AND THEIR EYES. to 40 mm. in length the clinroid fissure is a well-marked structure. The pigment layer and inner lasers merge into each other here, and the ganglionic layer is con- tinuous with the pigment layer. As stated above, the inner reticular layer does not surround the ganglionic layer at this point. A vertical longitudinal section of the eye has the general appearance of a section through a Graafian follicle (fig. 41 a). The ovum would correspond in position to a cell in th
. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. 124 BLIND VERTEBRATES AND THEIR EYES. to 40 mm. in length the clinroid fissure is a well-marked structure. The pigment layer and inner lasers merge into each other here, and the ganglionic layer is con- tinuous with the pigment layer. As stated above, the inner reticular layer does not surround the ganglionic layer at this point. A vertical longitudinal section of the eye has the general appearance of a section through a Graafian follicle (fig. 41 a). The ovum would correspond in position to a cell in the ganglionic layer, the stalk ^^^?%.'"-. I'IG. 42. (a) Verlic:il Seclion through Left Eye of Individual 2=; tnni. lonR. (b) Vertiral Section through Left Eye of Specimen 40 mm. long. Inner Layer of Cells of Uvea shows well as a Series of Elongated Nuclei, til. I. Section, wfiile passing through Ganglionic Layer, does not pass through i'upil. of the ovum to the lips of the fused choroidal fissure, the outer follicular cells to the nuclear layers, antl the interior cavity of the follicle to the inner reticular layer of the eye. Optic Nerve. — The optic nerve is not as distinct at its exit from the ganglionic layer as in Amhlyopsis, but in specimens even 40 mm. long there is no difficulty in tracing it to the brain. In specimens of the latter size it has a diameter of g /x. It contains many elongated nuclei, some of which are also seen with the optic fibers within the eye (fig. 42 h). The covering of the optic nerve partakes of the same. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Eigenmann, Carl H. , 1863-1927. Washington, D. C. , Carnegie Institution of Washington
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