Discs missing or degenerate; mitotic index of larval ganglion cells three times that of controls; 20% of metaphases polyploid; very few anaphase figures seen. No maternal effect of homozygosis in ovarian clones on phenotype of offspring (Perrimon, Engstrom, and Mahowald, 1984, Dev. Biol. 105: 404-14). l(1)dd4S recovered as a mutation on the paternal X in a cross of homozygous mei-9 females by normal males [isolated as l(1)08/20]. Ordinarily dies just prior to eclosion, but in dry cultures, both males and females eclose and have good viability, but are almost completely sterile. Wings are held up, some bristles on head and thorax (especially scutellars) are absent; abdomen mutant effects similar to those of bb. Females heterozygous for l(1)dd4S and a deficiency are almost completely lethal.