WHEN unfertilized eggs of sea-urchin, Pseudocentrotus depressus (A. Agassiz), are inseminated immediately after the irradiation with gamma- or beta-rays of medium, the time of their first cleavage is prolonged roughly in proportion to doses1. This phenomenon has the same tendency to that already reported by Henshaw2 and others, who used roentgen rays and ultra-violet light. Recently, we have studied the effect of alpha-ray irradiation and obtained quite different results.
Miwa, Yamashita and Mori, Gann, 33, 1 (1939).
Henshaw, P. S., Amer. J. Roent., 27, 890 (1932).
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MIWA, M., YAMASHITA, H. & MORI, K. Lethal Action of Alpha-Rays on Sea-Urchin Eggs. Nature 144, 378 (1939). https://doi.org/10.1038/144378a0