The Induction of Recessive Lethals in Drosophila Oocytes.

ORK on recessive lethal mutation in Drosophila sperm has suggested ways win which chromosome breakage may be related to recessive lethal mutation, through position effect, deficiency, and as a direct result of breakage. The increase in aged oocytes of radiation-induced dominant lethals (PARKER 1959) and of rearrangement, the slower rejoining of breaks (PARKER and HAMMOND 1958) , and the higher yield of deficiency and of exchange between attachedX and a major autosome (PARKER and MCCRONE 1958), suggest that the effects of the aging of these cells on the induction of recessive lethals by irradiation might throw some light on the possible relation of their induction to breakage and rejoining. The probability that a break will restitute, rejoin, or fail to rejoin may differ considerably in different stages.