Archive image from page 98 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar_0 Year: 1920 in GERM-TRACK 83 and gradually disappear, and a new set of granules makes its appearance in the next prophase. As the granules of the preceding mitosis have not quite disappeared by the time the new set develops, the cell is never altogether without them, and this fact makes its continuous identification possible. The new granules appearing at prophase are again concen- Fig. 39. Differentiation of the germ-track in Cyclops fuscus (A
Archive image from page 98 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar_0 Year: 1920 in GERM-TRACK 83 and gradually disappear, and a new set of granules makes its appearance in the next prophase. As the granules of the preceding mitosis have not quite disappeared by the time the new set develops, the cell is never altogether without them, and this fact makes its continuous identification possible. The new granules appearing at prophase are again concen- Fig. 39. Differentiation of the germ-track in Cyclops fuscus (A-H), and Diaptomus coeruleus (I). (After Amma, , 1911.) A, prophase of first cleavage mitosis, granules congregated round one attraction sphere; B, same mitosis, metaphase; C, 2-cell stage, resting nuclei (note gonomery) ; D, prophase of second cleavage division; E, 16-cell stage. All the nuclei have completed their division, and entered into the resting stage, except that of the granule cell which is still in anaphase. F, division of the granule cell into the two primitive germ-cells; G, H, I, later stages. g, primitive germ-cells. trated round one attraction sphere only, and thus again pass into only one of the daughter cells. A differential cell division of this sort takes place four times, so that the cleaving egg up to the end of the 16-cell stage contains one, and only one, cell with granules, or granule cell. The nucleus of this cell does not as yet differ markedly from those of the other cells, except that it constantly lags a little behind the others in mitosis. 1
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