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  • 1925-1929  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 23-81 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flagellate, Tetramitus rostratus Perty, appeared in cultures of certain amoebae obtained from the coecum of rats. In a typical life-cycle a cyst, planted in an appropriate medium, gives rise to an amoeba which may divide a number of times, but eventually some of the amoebae transform into flagellates identical with Tetramitus rostratus. These divide frequently through several days, sometimes for weeks or months, and then transform back to amoebae which become encysted.During excystment the smooth cyst wall dissolves. Usually both the amoeboid and flagellate phases pass into a “gel” state during division. A “gel” state sometimes occurs during transformation. The time required for transformations varies from a few minutes to several hours.Many culture media and methods have been tested. In certain cultures the flagellate phase was prolonged for weeks or months. These cultures were characterized by: 1) great variation in size, from minute “dwarfs” to oversized “monsters”; 2) frequent multiple fission; 3) pairing and fusion, and, 4) some evidence for the origin of secondary nuclei from chromidia. In cases of pairing and fusion, the process of maturation and union of nuclei could not be definitely proved, although suggested by the observations.The flagellate phase is more probably the “adult” phase because of its complex organization and possible sexual phenomena. This case is considered an extreme for this type amoeba-flagellate transformation.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 47 (1929), S. 37-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vesicular nucleus of this amoeboflagellate is similar in structure in both phases of its life-cycle. It has a fairly large caryosome surrounded by a pericaryosomal area in which there are small oxyphilic pericaryosomal granules on a fine reticulum. On the inner surface of the definite caryotheca is a layer of epithecal chromatic granules.Nuclear division is similar in both amoeba and flagellate phases. During the prophase the nucleus enlarges, and the expanded caryosome becomes resolved into basophilic and oxyphilic components and assumes either an oblong, dumb-bell, or spindle shape. The pericaryosomal granules enlarge, shift about, and eventually become arranged in an equatorial band around the elongated caryosome. In the metaphase the equatorial plate of chromosomes appears after the inward migration of the pericaryosomal granules, accompanied by the formation of a definite intranuclear spindle, usually with polar masses, polar granules, and a centrodesmose. After the poleward migration of the daughter plates of chromosomes in the anaphase, the telophase constriction of the nuclear membrane produces two daughter nuclei with a portion of the spindle remaining outside. The epithecal layer of granules remains in place on the nuclear membrane during the entire process of mitosis. Plasmotomy normally follows mitosis, but may be delayed, giving rise to multinucleate individuals. In the flagellate the blepharoplast usually divides simultaneously with, but independently of, the nucleus. There are many divergences in the details of mitosis, but these are thought to be variations of one type of division rather than examples of different processes.
    Type of Medium: Electronic Resource
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