260 



Morris Rockstein 



young parents to 22 days for females from very old parent 

 flies. In the case of Lansing's parthenogenetically reproducing 

 rotifers, his "cumulative reversible aging factor" could be 

 directly attributable to cessation of growth in the old female 

 parent. In the present study, however, several interpreta- 

 tions were possible for the sexually reproducing housefly; 



Table III 



Effect of parental age of houseflies on 

 longevity of offspring 



either or both of the old parents might be contributing to the 

 reduced female offspring longevity which is associated with 

 the advancing age of the parents at oviposition. A second 

 possibility is that the observed data represent the adverse 

 effect of long-term storage of spermatozoa in the female 

 spermatheca. With Dr. Lieberman, an expanded study of the 

 possible r61e of parental age in the longevity of the housefly 



