Stage 12–15 wildtype, blow, loner, mbc, kette, rac and rols mutant embryos were stained with antibodies against Eve (DA1, A–B) or Runt (DO2, C–D) in combination with phalloidin (see text). The number of nuclei for each muscle and stage were counted in 50 hemisegments (A2–4). (A, C) Bar graphs showing the mean number of nuclei in the DA1 (A) and DO2 (C) muscles at each stage in each genotype. Error bars show one standard deviation from the mean. For each muscle two classes of fusion mutants were observed. The first class showed almost no fusion and included blow, loner and mbc. The second class showed limited fusion and included kette, rac and rols. The second class of fusion mutants showed fusion at all stages. (B, D) Histograms showing the percentage of fusion events that occur during each stage for each mutant during the course of fusion (7.5–13 hours AEL). The mean number of nuclei observed for each mutant at stage 15 is 100% and a single nucleus is 0%. The numbers used to plot these graphs are shown in Supplemental Table 2 and Supplemental Table 3. Fusion is observed at all stages of fusion independent of the number of fusion events that occur.