. Darwin, and after Darwin. An exposition of the Darwinian theory and a discussion of post-Darwinian questions. Evolution; Heredity. Embryology. 129 I will quote the following description of them, because, for terseness combined with lucidity, it is unsur- passable. Researches, chiefly due to Flemming, have shown that the nucleus in very many tissues of higher plants and animals con- sists of a capsule containing a plasma of " achromatin," not deeply. Fig. 36.—Karyokinesis of a typical tissue-cell (epithelium of Sala- mander). (After Flemming and Klein.) The series from A to I repres
. Darwin, and after Darwin. An exposition of the Darwinian theory and a discussion of post-Darwinian questions. Evolution; Heredity. Embryology. 129 I will quote the following description of them, because, for terseness combined with lucidity, it is unsur- passable. Researches, chiefly due to Flemming, have shown that the nucleus in very many tissues of higher plants and animals con- sists of a capsule containing a plasma of " achromatin," not deeply. Fig. 36.—Karyokinesis of a typical tissue-cell (epithelium of Sala- mander). (After Flemming and Klein.) The series from A to I represents the successive stages in the movement of the chromatin fibres during division, excepting G, which represents the "nucleus- spindle " of an egg-cell. A, resting nucleus; D, wreath-form; E, single star, the loops of the wreath being broken ; F, separation of the star into two groups of U-shaped fibres; H, diaster or double star; I, completion of the cell-division and formation of two resting nuclei. In G the chromatin hbres are marked a, and correspond to the "equatorial plate"; b, achromatin fibres forming the nucleus- spindle; c, granules of the cell-protoplasm forming a "polar ; Such a polar star is seen at each end of the nucleus-spindle, and is not to be confused with the diaster H, the two ends of which are composed of chromatbi. stained by re-agents, ramifying in which is a reticulum of " chro- matin " consisting of fibres which readily take a deep stain. I Fig. 36, A). Further it is demonstrated that, when the cell is about to divide into two, definite and very remarkable move- ments take place in the nucleus, resulting in the disappearance of the capsule and in the arrangement of its fibres first in the * K. 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 w
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