. The cell in development and inheritance. Cells. 3o6 THEORIES OF INHERITANCE AND DEVELOPMENT E. Critique of the Roux-Weismann Theory From a logical point of view the Roux-Weismann theory is unas- sailable. Its fundamental weakness is its (///cri-Z-metaphysical char- acter, which indeed almost places it outside the sphere of legitimate scientific hypothesis. Not a single visible phenomenon of cell-divi-. C D Fig. 132. —Half and whole cleavage in the eggs of sea-urchins. A. Normal i6-cell stage, showing the four micromeres above (from Diiesch, after Selenka). B. Half i6-cell stage developed fro
. The cell in development and inheritance. Cells. 3o6 THEORIES OF INHERITANCE AND DEVELOPMENT E. Critique of the Roux-Weismann Theory From a logical point of view the Roux-Weismann theory is unas- sailable. Its fundamental weakness is its (///cri-Z-metaphysical char- acter, which indeed almost places it outside the sphere of legitimate scientific hypothesis. Not a single visible phenomenon of cell-divi-. C D Fig. 132. —Half and whole cleavage in the eggs of sea-urchins. A. Normal i6-cell stage, showing the four micromeres above (from Diiesch, after Selenka). B. Half i6-cell stage developed from one blastomere of the 2-cell stage after killing the other by shaking (Driesch). C. Half blastula resulting, the dead blastomere at the right (Driesch). D. Half-sized i6-cell stage of Toxopneiistes, viewed from the micromere-pole (the eight lower cells not shown). This embryo, developed from an isolated blastomere of the 2-cell stage, segmented like an entire normal ovum. sion gives even a remote suggestion of qualitative division. All the facts, on the contrary, indicate that the division of the chromatin is carried out with the most exact equality. The theory of qualita- tive division was suggested by a totally different order of phenom- ena, and is an explanation constructed ad 'hoc. Roux, it is true, was led to the hypothesis through an examination of mitosis ; but it is. 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
