Statistical analysis of genetic interaction between spir and tin, spir and Doc, spir and pnr, spir and CycA.

**The χ2 test reveals in all three groups that the proportion of mutant and normal embryos is statistically different for single heterozygous and double heterozygous embryos.*The χ2 statistic is not significant at the 0.05 level, but at the 0.1 level.#Mutant hearts in these double heterozygotes denote gap phenotype.