for different radiations. He has demonstrated excellent families of curves which show, for examrle, a decrease in thymic weight of 35 and 10 ver cent respectively for the sane doses of 250 and 1000 k.v. x-rays. The spleens are weighed immedietely after autopsy of the animals, but the thymus is placed in formalin over nizht to permit easier separation of the fat. 1300 sevarate weighings will be done in paired weighing bottles for each test. élances, He has five 28 regular staff of seven and will add seven other helpers to his group after each test. A trial run using 250 k.v. x-rays will be conducted on Japtan on the generation of mice voreceding those actue!ly used in the first test. Mouse Experiments (other than dosimetry) The Fy hybrids of the LAF strain are being used because they zive the nost consistent data on mortality studies according to Cronkite and Lorenz. 1. Mortality vs. for gan ™a distence: rays. This will only be determined There will be thirty animals of eech sex in the twenty-nine cylindrical stations, which sre so placed that they will receive increasing doses of genna reys in increments of °5 roentgens. “he probable dose renge which will be covered is 40-1200, but it may be 50-1400, or 80-1600 r., denending unon the bomb efficiency. I don't think these animals will be autopsied. Should be recovered in 4-5 hours. They Lethe] dose studies under simulated field conditions have been comnleted at Eunter's Foins. DO’ ARCHIVES