By means of the agar plate method, the action of p-acetylaminotropolone on mitosis was investigated in Tradescantia cells in vivo.
In a concentration of 0.00005 and 0.000005 mol. solutions of p-acetylaminotropolone, mitoses occur de novo, which show chromosome bridges as well as chromosome fragments, when they enter into telophase. In higher concentrations than the above mentioned, several kinds of abnormal mitoses appear necrobiotically; or the occurrence of de novo mitoses is suppressed.
In the Tradescantia test in vivo, two kinds of chromosome fragments are found; the occurrence of the first is confined to the resting stage or to the early prophase; this may be caused by the action of p-acetylaminotropolone. The occurrence of the second is in telophase and is caused by the refragmentation of the primary fragments, which are torn off by the developing cell plate or by the developing daughter nuclear membrane.
From the standpoint of cell biology, the alteration of mitotic cell contents due to the change of concentration of chemicals; and the biological significance of the abnormalities of the mitosis which may appear in fixed preparations and in the necrobiotic as well as in the living state of the cell were discussed.