Abstract
1. The leukocyte value in the peripheral blood of three different strains of mice was followed after a single dose of whole body x-radiation. The maximum leukocyte depression was used as a basis for comparing the biologic effectiveness of the betatron radiation and the 200 KV x-radiation.
2. The ratio of effectiveness in producing 70 per cent leukocyte reduction, for betatron radiation to 200 KV x-radiation, for the three strains was 0.65.
3. The onset of recovery from leukopenia for equal doses of radiation occurred earlier in animals treated with betatron radiation than in those treated with a similar dose of 200 KV x-radiation.
4. The degree of leukopenia and delay in recovery was found to increase somewhat with age of animals treated with 200 KV x-radiation and to a less extent in animals treated with betatron radiation.
5. At a dose of 600 r, over 90 per cent of the animals treated with 200 KV died within a few days, while none of the animals exposed to the same dose of betatron radiation died in the same period. The leukocyte count immediately before death was about 2 per cent of control values.
6. For a dose of 600 r, the lymphocytes were equally reduced by 200 KV and betatron radiation, while the granulocytes were much less reduced by betatron than by 200 KV radiation.
