Abstract
Thepretreatment of Tradescantia inflorescences with one atmosphere of CO2 plus one of air is effective in increasing the number of chromosome aberrations induced by X-ray by about 1.6 times. Separating the CO2 pretreatment and radiation by increasing periods in air has shown that the CO2 effect persists for about 20 minutes. After this period the aberration frequency returns to control levels. Following the CO2 treatment the oxygen uptake rate of the tissues is greatly increased. There is reason to believe that changes in nucleoplasmic viscosity and oxidative metabolism may alter the frequency of chromosome aberrations induced by radiation.