. The cell in development and inheritance. Cells. PRELIMINARY GEXERAL SKETCH 195 cleavage before the first cleavage takes place. The minute centro- somes of the second cleavage are therefore the direct descendants of the sperm-centrosome ; and there is good reason to believe that the continuity is not broken in later stages. The facts are nearly similar ^. •"^.. •• < /*p^ •. •. B \ C. Fig. 99. — Fertilization in an annelid (armed Geptiyrean), Thalassema. [GRIFFIN.] A. Second polar body forming; sperm-nucleus and centrosome below. B. Approach of the egg-nucleus and sperm-nucleus, the la
. The cell in development and inheritance. Cells. PRELIMINARY GEXERAL SKETCH 195 cleavage before the first cleavage takes place. The minute centro- somes of the second cleavage are therefore the direct descendants of the sperm-centrosome ; and there is good reason to believe that the continuity is not broken in later stages. The facts are nearly similar ^. •"^.. •• < /*p^ •. •. B \ C. Fig. 99. — Fertilization in an annelid (armed Geptiyrean), Thalassema. [GRIFFIN.] A. Second polar body forming; sperm-nucleus and centrosome below. B. Approach of the egg-nucleus and sperm-nucleus, the latter accompanied by the sperm-amphiaster. C. Union of the nuclei. D. Later stage of last. E. Prophase of cleavage-spindle, i^". Ana[)hase of the same; centrosome divided. G. H. I. Successive stages in the nuclear reconstitution and formation of the daughter-amphiasters for the second cleavage, jf. Two-cell stage. in the trout, in ChcBtopter7is, and in PJiysa. In Ascaris division of the centrosome first occurs at a somewhat later period (Figs. 90, 176). If now the centrosomes were indeed permanent cell-organs, we should thus reach the following result: During cleavage the cytoplasm of the blastomeres is derived from that of the egg, the cetitrosomes from. 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 Wilson, Edmund B. (Edmund Beecher), 1856-1939. New York, Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectcells, bookyear1911
