Carnegie Institution of Washington Publication Volume 104

Carnegie Institution of Washington Publication Volume 104

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 edition. Excerpt: ... present and forming a solid core of cells behind the vitreal region inclosing blood-vessels and hyaloid nuclei. Some of the cells appear to send fibers into the inner nuclear layer in the older retinas. These may be Miillerian nuclei, since in Chologaster comntus such are found in this layer. The total number of nuclei counted in one example as belonging to this layer is I00, not very greatly difierent from the number noticed in specimens of Amblyopsis. In specimens up to 40 mm. in length the choroid fissure is a well-marked structure. The pigment layer and inner layers merge into each other here, and the ganglionic layer is continuous 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 of the ovum to the lips of the fused choroidal fissure, the outer follicular cells to the nuclear layers, and 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 Amblyopsis, 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 9 p.. It contains many elongated nuclei, some of which are also seen with the optic fibers within the eye (fig. 42 b). The covering of the optic nerve partakes of the same indefinite nature as that of the eye itself, with which it is continuous. No pigment accompanies the nerve as a distinct layer, but here and there, as in the covering of the eye, a pigment cell...show more

Product details

  • Paperback | 118 pages
  • 189 x 246 x 6mm | 227g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236993462
  • 9781236993465