The Effect of Temperature on the Mutation Rate in Drosophila Melanogaster

The incidence of sex linked recessive lethal mutations in Drosophila melano gaster after heat shock treatment of both larvae and adult males is reported. There was no increase in the mutation rate after treatment of larvae and the results with adult males were not consistent. Treatment of the latter at 38 C caused an increase in mutation rate, due apparently to the large response of a few sensitive males. Treatment at 40 C caused no increase, and if one sensitive male was excluded, the mutation rate was significantly less than control. These results do not entirely support those of previous workers in the literature and possible reasons for this are discussed.