183¢ 2 1% Fa oy? hes couuainmasm c Data accumulated on the parent fish following their spawning in the spring of 1945 are being evaluated. Mortality, growth and other radiation syndromes are being analysed. The data indicates that Xeray dosages of 1500 and 2500 r are 90% and 100% lethal respectively in 64 weeks, Growth in length and weight appears to be retarded by irradiation of 750 or 100r with definite symptoms of X-ray damage sean in trout exposed to such. intensities. Project VI. Exposure of invertebrates to X~rays,. On November 16, 1948, the report entitled, "Lethal effects of X-rays on Marine Amphipods® (U"FL~14), Kelshaw Bonham was submitted to the Commission Marine snails, Thais lamellosa, of the two experiments started July 6 and October 20, 1948, survived the month in apparently good condition except for a control specimen in the second experiment which had detached from the substratum and remained withdrawn for 3 or 4 weeks. On November 22 this specimen was sacrificed and was found to be quiescent, almost moribund, and to have its operculum almost completely dissolved. Toward the end of the month, breeding congregation, behavior and a few abortive egg cases were observed. Fresh water snails brought October 24, 1948, from the oreek in Richland, Washington by R. F. Foster, were X-rayed on November 12. Groups of 8 snails each were given single doses in roentgens of 500, 1000, 2500, 5000, 10000, 20000, 40000, or 80000 at the rate of 500 r per minute, with 36 control snails. Four days later on November 16 all