Induction of Triploidy and Haploidy in the Newt, Triturus Viridescens, by Cold Treatment of Unsegmented Eggs

Abstract

GRIFFITHSsame dosage given at low intensity.Continuous radiation is more effective than intermittent radiation.The effect of the time-intensity factor is due to the fact that the chromosome aberrations are dependent upon two independent x-ray hits, limited in time and space.Intense radiations produce many adjacent breaks during the critical time period and fusions may occur between different chromosomes.If the radiation is given slowly, the first break may heal before a second break occurs in an adjacent chromosome.The broken ends of both chromosomes reunite in the original position and no aberration is produced.The time-intensity factor has no effect on 1-hit chromatid aberrations.The broken ends of Tradescantia chromosomes may remain in an unstable condition and capable of fusion for a maximum period of about an hour.The work was supported, in part,