Chromosome 3 of corn carries three loci (b for plant-col- or booster, v for virescent, and lg for liguleless). a test- cross of triple recessives with f1 plants heterozygous for the three genes yields progeny having the following genotypes: 305 + v lg, 275 b + +, 128 b + lg, 112 + v +, 74 + + lg, 66 b v +, 22 + + +, and 18 b v lg. give the gene sequence on the chromosome, the map distances between genes, and the coefficient of coincidence.