By means of phase cinematography the behavior of the daughter chromosome groups was investigated in silkworm spermatocytes exposed at telophase to ultraviolet microbeam partial irradiation. Information was obtained that in cells received microbeam irradiation in a restricted part at telophase the daughter chromosome group moved rapidly from the irradiated pole toward the non-irradiated opposite pole. Exposure to several other parts or to two poles in telophasic cells induced no such an unusual behavior of chromosomes.