2. Investigation of the effects of neutrons using biological dosimeters showed that at the distance at which gamma radiation is still a significant biomedical hasard the contribution of neutrons to the total dese is not significant. The neutron flux is variable and will depend upon the assembly of the weapon. 3. Anatomical, histological, and other features of atomic bomb flash burns can be satisfactorily produced by intense thermal sources now available in the laboratory. It was demonstrated that no burning takes place during 20-30 milliseconds after detonation of an atomic bomb, and that all thermal injury occurred in less than one second, It was also shown that ultraviolet light from the bomb did not contribute significantly tothe thermal injury. 4. Foxholes afford reasonable emergency shelter against blast and radiation, depending, of course, upon yield and distance from ground zero, 5. 6. Occupants of aircraft passing through the stem of an atomic cloud are exposed to greater hazard from gamma radiation from external sources than from radiation from inhaled bomb debris. The use of plants, such as Tradescantia, as biological dosin~ eters may be feasible. The number of breaks in the chromo~ somes of Tradescantia axposed to bomb radiation correlated very closely with dosages for I and gamm rays, and for neutron dosage when gamma radiation was sereaned out, thus providing as exact a measure of radiation as film badges or instruments. Research Activities Savannah River Site Bilolo y (UNCLASSIFIED) Two conferences were held in April in connection with the Biological Survey being conducted under the general direction of the Savannah River Project. All phases of the program were reviewed in detail. The over-all survey is aimed to assure that initial shanges in the fauna and flora of the region due to plant operation or released radioactivity shall be recognized immadiately and corrected. The program is divided into the following four major subdivisions: DO ARCHIVES