Abstract
Measurement was made on the riboflavin content in the organs of mice which were subjected once to whole body X-rays irradiation. Within 24 hours after 850 or 550 r irradiation, a decrease was observed in the riboflavin content in the liver and kidney, which seems to be primary change due to irradiation. The riboflavin content in the liver and kidney began to lower again 5-7 days after irradiation, and the most marked decrease was observed 10-14 days thereafter. The change seems to have been caused by the accumulation of the secondary changes. Only a slight change was recognized in the riboflavin content in the heart and muscle. Primary change after 350 r irradiation bore a startling resemblance to those after irradiation more than 550 r, but these secondary changes were lacking in the regularity due to the differences among individuals.
