. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 909 bulletin: museum of comparative zoology. More theoretical and farther from the truth Eabl could scarcely be, yet several investigators have in essential respects confirmed his theory, that the oculomotorius is a derivative of the nem-al crest. Dohrn's ('91) observations, however, differ fundamentally from those of his predecessors. He sees the beginnings of the oculomotorius in em- bryos intermediate between Balfour's stages I and K. At first cells in the base of the brain assume a more transparent appear
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 909 bulletin: museum of comparative zoology. More theoretical and farther from the truth Eabl could scarcely be, yet several investigators have in essential respects confirmed his theory, that the oculomotorius is a derivative of the nem-al crest. Dohrn's ('91) observations, however, differ fundamentally from those of his predecessors. He sees the beginnings of the oculomotorius in em- bryos intermediate between Balfour's stages I and K. At first cells in the base of the brain assume a more transparent appearance, and later migrate into the " Randschleier," where they send out processes which unite in a network just outside the base of the brain to form the stem of the nerve. Immediately at the beginning of the outflow of the plasma. cells are seen half in and half out of the wall of the tube, and later, but before the oculomotorius has any connection with the mesocephalic ganglion, large deeply staining nuclei are seen in the protoplasmic net- work which forms the root of the nerve. Dohrn does not lay great stress on the fact that these nuclei are larger than those of the surround- ing raesenchyma cells, but from the fact that similar nuclei lie nearer the medullary wall, from which they appear to emerge in increasing numbers during the course of development, he holds the opinion to be permissible, that the nuclei of the early network are emerged raedullai-y elements, and not mesoderm cells which press close to the medullary Fig. G. a portion of the same section as that shown in Figure F. X 240. Tlie fibrillar nature of the oculomotorius is clearly shown, ax-cyl, axis cylinder process; cl. nil., neuroblast cell; oc-mot., 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 Harvard Universit
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Keywords: ., bookauthorha, bookcentury1800, bookdecade1860, booksubjectzoology
