. The cell in development and inheritance. Cells; Cells. 3i6 THEORIES OE INHERITANCE AND DEVELOPMENT ment. And if the germinal localization is not directly determined by the nuclei it must here be determined by a pre-organization of the cytoplasmic substance. How is this result to be reconciled with the experiments on AnipJiioxiis and the echinoderms, and with the more general conclusion that the ultimate determining causes of differentia-. Fig. 139. — Partial development of isolated blastomeres of the gasteropod egg, Ilyanassa. [Crampton.] A. Normal 8-cell stage. B. Normal 16-cell stage. C. H
. The cell in development and inheritance. Cells; Cells. 3i6 THEORIES OE INHERITANCE AND DEVELOPMENT ment. And if the germinal localization is not directly determined by the nuclei it must here be determined by a pre-organization of the cytoplasmic substance. How is this result to be reconciled with the experiments on AnipJiioxiis and the echinoderms, and with the more general conclusion that the ultimate determining causes of differentia-. Fig. 139. — Partial development of isolated blastomeres of the gasteropod egg, Ilyanassa. [Crampton.] A. Normal 8-cell stage. B. Normal 16-cell stage. C. Half 8-ceU stage, from isolated blasto- mere of the 2-cell stage. D. Half 12-cell stage succeeding. E. Two stages in the cleavage of an isolated blastomere of the 4-cell stage; above a one-fourth 8-cell stage, below a one-fourth 16-cell stage. tion are to be sought in the nucleus ? The difficulty at once disap- pears when we recall that development and differentiation do not in any proper sense first begin with the cleavage of the ovum, but long before this, during its ovarian history. The primary differentiations thus established in the cytoplasm form the immediate conditions to which the later development must conform ; and the difference. 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 : The Macmillan company
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectcells, bookyear1896
