. The cell in development and inheritance. Cells. B Fig. 124. —• Partial or meroblastic cleavage in tlie squid Loligo. [Watase.] Balfour's law undoubtedly explains a large number of cases, but by no means all; for innumerable cases are known in which no cor- relation can be made out between the distribution of inert substance and the inequality of division. This is the case, for example, with the teloblasts mentioned above, which contain no deutoplasm, yet regularly divide unequally. It seems to be inapplicable to the in- equalities of the first two divisions in annelids and gasteropods. It is
. The cell in development and inheritance. Cells. B Fig. 124. —• Partial or meroblastic cleavage in tlie squid Loligo. [Watase.] Balfour's law undoubtedly explains a large number of cases, but by no means all; for innumerable cases are known in which no cor- relation can be made out between the distribution of inert substance and the inequality of division. This is the case, for example, with the teloblasts mentioned above, which contain no deutoplasm, yet regularly divide unequally. It seems to be inapplicable to the in- equalities of the first two divisions in annelids and gasteropods. It is conspicuously inadequate in the history of individual blastomeres, where the history of division has been accurately determined. In Nereis, for example, a large cell known as the first somatoblast, formed at the fourth cleavage (.V, Fig. \22, E), undergoes an inva- riable order of division, three unequal divisions being followed by an equal one, then by three other unequal divisions, and again by an equal. This cell contains no deutoplasm and undergoes no percepti-. 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
