Downloaded from https://academic.oup.com/genetics/article/23/5/494/5937004 by guest on 27 April 2021 X-RAY INDUCED ABERRATIONS 495 of the meiotic and mitotic cycles is increased during the winter months and may be increased to two weeks for each cycle. All experiments were done with a clonal line of a Tradescantia reflexa hybrid, which has six pairs of chromosomes and one pair of fragments. Flowering stalks were cut off and kept in a glass of water during radiation and for several days to a

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... more while the microspores were being examined. When the microspores were to be examined for a period of several weeks after irradiation, the potted plants were subjected to X-rays. The source of the X-rays was a Coolidge tube with a tungsten target. The line voltage was 1 2 0 a t IO ma, and the secondary voltage was 160 kv.