Studied by 4nderson of C.1.7T., who meade observetions on the Bikini corn. Controls have been studied cerefully with 250 k.v. x-reys end with water boiler neuts. at hos Alemos. Tredescantia: Inflorescence will be placed et close stations end plants at fer stations. Dr. Conger of Cak Ridge will be in cherge of this study. nears of the pollen will be mede at 21 hours and four days after exposure (the two clessical times of study) end some of the Scoring of the chromosome breaks will be made et Jgaptan. This tyne of Study is of perticular importence in the stidy of neutrons as the increase in breeks is not (?} lineer in the case of genta rays when the dose exceeds 250 roentgens. Io presume that the neutron studies with fission, pile end cyclotron neitrons such es have been resorted in the literatire are being continued. The tradescentia will be placed in the hemispnerical stetions where they will receive an estimated 10°? to 10? neuts (lergely fast) end not nore tnen 30 gamra roentgens. They will 4130 be pleced in the cylindrical stetions where they Will be exposed n-inly to ganze rays. Mouse spleen-thynus weight Jecrease: en excellent +nd novel ides, This is but it is the least well explored of the biological tests (excert for the inhaletion). Carter at Los Alamos has studied this problem thoroughly with neuts. and photons of different energies end has calibrated the weight decrease in these lympnoid tissues qu US DCE ARGdIY S Aq