. The cell in development and inheritance. Cells. \ Fig. 50.— Pigment-cells and asters from the epidermis of fishes. [ZiMMERMANN.] A. Entire pigment-cell, from Dlennius. The central clear space is the central mass of the aster from which radiate the pigment-granules; two nuclei below. B. Nucleus («) and aster after ex- traction of the pigment, showing reticulated central mass. C. Two nuclei and aster with rod- shaped central mass, from strong, if indirect, argument is thus given in favour of contractility in other forms of asters.^ The contraction-hypothesis is beautifully illustrated
. The cell in development and inheritance. Cells. \ Fig. 50.— Pigment-cells and asters from the epidermis of fishes. [ZiMMERMANN.] A. Entire pigment-cell, from Dlennius. The central clear space is the central mass of the aster from which radiate the pigment-granules; two nuclei below. B. Nucleus («) and aster after ex- traction of the pigment, showing reticulated central mass. C. Two nuclei and aster with rod- shaped central mass, from strong, if indirect, argument is thus given in favour of contractility in other forms of asters.^ The contraction-hypothesis is beautifully illustrated by means of a simple and easily constructed model, devised by Heidenhain ('94, '96), which closely simulates some of the phenom- ena of mitosis. In its simplest form the model consists of a circle, marked on a flat surface, to the periphery of which are attached at equal 1 For an interesting discussion and development of the contraction-hypothesis see "Watase, ' 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
