Abstract
Previous observations showing that there are 2 classes of radiation inactivation for bacterial spores are extended to germinating forms. Spores which inactivate in a "multiple target" fashion inactivate in a "two target" fashion upon germination, whereas spores which inactivate in a "single target" fashion inactivate in a "single target" fashion upon germination. Spores of the "multiple target" class seem to have a higher content of dipicolinic acid per gram of dry spore material than do those of the "single target" class.