File:Philodromus limbatus segmentation.jpg
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| Description | FIG. 53. THREE STAGES IN THE SEGMENTATION OF PHILODROMUS LIMBATUS. (After Hub. Ludwig.) The Eupagurus type, with the division of the first nucleus into eight nuclei before the division of the ovum, must be regarded in this light; but the most instructive example of such a transitional type of segmentation is that afforded by Spiders. The first phenomenon which can be observed after impregnation is the conglomeration of the yolk spheres into cylindrical columns, which finally assume a radiating form diverging from the centre of the egg. In the centre of the radiate figure is a protoplasmic mass, probably containing a nucleus, which sends out protoplasmic filaments through the columns (fig. 53 A). After a certain period of repose the figure becomes divided into two rosette-like masses, which remain united for some time by a protoplasmic thread : this thread is finally ruptured (fig. 53 B). The whole egg does not in this process divide into two segments, but merely the radiate figure, which is enclosed in a finely granular material. The two rosettes next become simultaneously divided, giving rise to four rosettes (fig. 53 C) : and the whole process is repeated with the same rhythm as in a regular segmentation till there are formed thirty-two rosettes in all (fig. 54 A) |
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https://archive.org/details/theworks02balfuoft/page/116/mode/2up?view=theater&q=blastoderm THE WORKS OF FRANCIS MAITLAND BALFOUR VOL. III A TREATISE ON COMPARATIVE EMBRYOLOGY. |
| Author | M. FOSTER, F.R.S., ADAM SEDGWICK, M.A., |
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| current | 01:43, 1 March 2024 | | 1,011 × 719 (649 KB) | Rasbak (talk | contribs) | {{Information |description=FIG. 53. THREE STAGES IN THE SEGMENTATION OF PHILODROMUS LIMBATUS. (After Hub. Ludwig.) The Eupagurus type, with the division of the first nucleus into eight nuclei before the division of the ovum, must be regarded in this light; but the most instructive example of such a transitional type of segmentation is that afforded by Spiders. The first phenomenon which can be observed after impregnation is the conglomeration of the yolk spheres into cylindrical columns, whic... |
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