Abstract
Cultured hepatoma cells of the rat were irradiated with 400 to 900 R of gamma-rays. They were kept at room temperature for several hours before transferred to normal culture condition at 37°C. The pedigree analysis of growing cells recorded by cinematography indicated a variety of lethal and non-lethal recovery events such as a decrease in lethal branch formation and an increase in locomotion. The so-called repair immediately after irradiation has many facets depending upon dose and duration of the low temperature treatment.