Genetic effects of spermatogonial irradiation on growth and age at sexual maturity in rats.

INTEREST in the genetic effects of irradiation on quantitative characters usually takes the form of two questions. Does irradiation effect a genetic change in the mean of quantitative characters such as human intelligence? Does irradiation induce genetic variance in quantitative characters that could be utilized by the plant or animal breeder for genetic improvement? Experimental data relevant to these questions are scanty, especially in mammals, and the results of different experimenters are frequently inconsistent. The present data were collected in a long-term experiment designed primarily to estimate the frequency of induction of mutations affecting fitness.