“…With regard to those of D. melanogaster in Japanese populations reported Oshima and Kitagawa (1961), Oshima and Watanabe (1967), Minamori and Saito (1964), and Kosuda, Kitagawa, and Moriwaki (1969). Oshima and Watanabe (1967) analyzed the deleterious genes on the second chromosomes extracted from natural populations in Kof u and Katsunuma localities every autum since 1963, and the mean frequency of lethal chromosomes was found to be 14.6 per cent, but the third chromosomes were at that time not analyzed.…”