The founder animal of strain vg-182 was isolated as a Large Roller progeny of an EMS treated C. briggsae (G16) hermaphrodite. It has segregated only a few offsprings including Lons and animals of variable phenotypes. Lon hermaphrodites were singled and self-fertilized through subsequent generations and then crossed out several times. During this process 7 of 8 fertile lines segregated Lon males, Large Dpy hermaphrodites, Small Dumpies and Large Rollers. At the end, loci represented by one X-linked dominant lon, one autosomal recessive dpy and one independent, autosomal squat allele, respectively, could be identified and named temporarily as
lon-2, dpy- 2 and sqt-l.
lon-2(d) proved a dominant epistatic gene over
dpy-2 and a semidominant epistatic one over sqt-l. (Worms of sqt-l; +/+;
lon-2 genotype exhibited Large Roller phenotype while those of sqt-l/+; lon- 2/0 genotype were large, Non-Roller males.) The male--segregating (Him) phenotype could not be separated from
lon-2(d). The
lon-2 hermaphrodites kept in liquid nitrogene still keep their 'him' phenotype, those which were kept in laboratory conditions lost their male-segregating ability. The possibilities of getting a mutator strain of C. briggsae are discussed.