HITING (1945), working on the parasitic wasp Habrobracon, developed a timing method that distinguished oocytes irradiated in the first meiotic metaphase (metaphase I) from those irradiated in the first meiotic prophase (prophase I) . She used embryo lethality of X-irradiated eggs from diploid virgins, which measured mostly dominant lethality, and found that metaphase I oocytes are approximately...

S long ago as 1921 HOLTHUSEN observed an effect of anoxia on X-rayed A cells. Interest in this factor and its relation to radiation damage has recently been revived. BACQ (1951) has reviewed the earlier work and latest developments have been described by HOLLAENDER, BAKER and ANDERSON (1951), HOLLAENDER (1952) and GILES (1952). One group of investigators has been concerned with the question as ...

INVESTIGATIONS to be reported in this paper have been concerned chiefly whh X-ray-induced embryonic lethal mutations in Habrobracon. Some of the data and one of the methods have already been given (HEIDENTHAL 1952, 1953; HEIDENTHAL, C ARK and GOWEN 1955). The purpose of the author's work, as well as that of others, has been in part to study the frequency of different kinds of lethal-bearing gen...