Gonadal mosaicism as a factor in determining the ratio of visible to lethal mutations in Drosophila.

is well known, when sperm cells of Drosophila are treated with X-rays, Asrelatively few of the induced mutations are visibles; the great majority are lethals. In the case of chemical mutagens, the results are somewhat different. According to work reported by the FAHMYS (1956) chemical mutagens induce a relatively high visible rate. The FAHMYS have concluded that chemical mutagens have a specific effect on visible loci. However, CARLSON and OSTER (1961) have suggested that the high visible rate in question might be associated with gonadal mosaicism. The present studies confirm this suggestion.