A genetic analysis following the initial detection of a female sterile variant resulted in the finding of seven or eight different female sterile mutants, most or all of which are on linkage groups I and II. They were present in heterokaryotic condition in already existing strains, except one which originated spontaneously during the study. All mutants fail to produce functional protoperithecia. Most of them, however, are able to function as female parents in heterokaryons. All mutants differ morphologically from the wild type, most being subtly different, but two being appreciably different. The apparently high frequency of occurrence of female sterile mutants suggests that protoperithecial development is under an elaborate genetic control. Differences in vegetative morphology appear to be a common property of mutants affecting the early stages of the sexual development.

Eight strains of wild-caught Drosophila melanogaster Meigen were tested for their responses to the insecticide malathion. The types of responses tested were behavioral resIstance (contact avoidance) and physiological resistance. For both types of responses, significant interstrain differences were detected. Avoidance index values for each strain and sex fell into five significantly different groups. No significant correlation was found between behavioral and physiological responses, indicating that the mechanisms involved are genetically independent of each other.

No abstract

The frequency of the more common patterns of non-disjunction in Neurospora was studied. Detection of these asci was accomplished by the use of pantothenate requiring strains grown on reduced amounts of pantothenate, so that combinations of dark, pale, and aborted spores provided evidence of non-disjunction. The isolates from five non-disjunction asci were examined in detail and an apparently high frequency of mitotic recombination was detected for presumed disomic isolates. An hypothesis concerning a mechanism of non-disjunction is presented.

By crossing a pair of albino strains each with a different adjacent nutritional marker and then crossing the same pair of albino markers with the nutritional markers transposed it was possible to order a series of al mutants with a resolution approaching that available for nutritional markers. A genetic map with approximated distances is provided demonstrating a grouping of mutant sites for a range of discrete carotenoidless phenotypes.