File:Journal of morphology (1893) (14782432972).jpg

Identifier: journalofmorphol08wist (find matches)
Title: Journal of morphology
Year: 1893 (1890s)
Authors: Wistar Institute of Anatomy and Biology
Subjects: Morphology Physiology
Publisher: Boston : Ginn & Co.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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lionic cell always grows toward theoptic stalk, as indicated in the figure. At the point of union,between the optic stalk and retina, there is always a triangularspace, and frequently the optic nerve grows through this.Along the growth of the nerve the cells are spindle shaped,and as it passes through the triangular space these cells sur- No. 2.) HISTOGENESIS OF THE RETINA. 425 round the nerve. The exact direction of the nerve does notseem to be constant, but, as a rule, it is towards the ventraland median side of the stalk, as indicated in Fig. 9. A sec-tion of the same stage in Necturus is shown in Fig. 10. Thewhole nerve was struck in one section, and it shows a verylarge triangular space, partly filled with cells which surroundthe nerve. The idea that the optic nerve arises from the retina and growsto the brain was first advanced by W. Muller ^ although he hadno direct observation on which to base his view. The variousfacts known at his time to histologists and embryologists were,
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Pig_ 10. — Section through the eye of Necturus (i8 mm. long) about the timeof hatching. X 100 times. however, sufficient basis and his view was finally verified simul-taneously by His 2 and Martin ^ by direct observation inmammalian embryos. The study of the latter is quite com-plete, and in general what I have found in the amphi-bian eye confirms what he found in the cat. He findsalso that the optic nerve not only arises from the ganglioncells but also from the cells of the inner nuclear layer. 1 W. Miiller, Festgabe an C. Ludwig, 1874. 2 His, His u. Braunes Archiv, 1S90. 8 Martin, Anatom. Anz., 1890, and Zeit. f. vergl. Augenheilkunde, Bd. 7. 426 MALL. (Vol. VIII. From another standpoint it was also shown by Froriep ^that the first fibers of the optic nerve must arise from theretina, because he found in a shark embryo an optic nervearising from the retina but not reaching to the brain. Thesame has been shown to be true by Keibel ^ and by Assheton.^In both Figs. 9 and 10, which arc

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