. Carnegie Institution of Washington publication. . '"â ^. Fig. 48.âSection passing between the point 1 and I of ihe segmentation stage shown in PI. IV, fig. 20. In the present section the line which appeared to indicate first cleavage lies below the point /'.â below this a vacuole is present whose lateral extent gives one the impression o( the width of the furrow noted m surface view, y 35. Fig. 49.âSection through a segmentation stage corresponding to PI. IV, fig. 22. It will be observed that some of the cleavage lines do not open to the surface, as at t. On the other hand, one of the s
. Carnegie Institution of Washington publication. . '"â ^. Fig. 48.âSection passing between the point 1 and I of ihe segmentation stage shown in PI. IV, fig. 20. In the present section the line which appeared to indicate first cleavage lies below the point /'.â below this a vacuole is present whose lateral extent gives one the impression o( the width of the furrow noted m surface view, y 35. Fig. 49.âSection through a segmentation stage corresponding to PI. IV, fig. 22. It will be observed that some of the cleavage lines do not open to the surface, as at t. On the other hand, one of the spaces between the blastomeres opens into a fissure-like vacuole, ti. Fig. 50.âSimilar section of early segmentation stage, in which, as at «, a nucleus appears without any neighboring cleavage furrow. A line of thicker germinal yolk appears in its place. Fig. 51.âSection of early cleavage stage in which, when viewed from the surface, deep, fissure-like vacuoles appear as cleavage lines. the others. As in the companion stage the furrows fade away at the margin of the germinal area, and this is again surrounded by a somewhat regular ring of merocyte eminences. It may be mentioned that these characters are materiall}' modified, /. e., as far as surface view is concerned, when the egg is hardened, e. g:, in acetic sublimate. And in sections it is found that the circumgerminal fosse and merocyte eminences disappear and what was interpreted as surface furrows in the living egg appear as long and wide vacuoles. Thus in fig. 48, a section transverse to the. 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 Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
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