Abstract
Seven alleles of the pyridoxine locus of Neurospora were mapped by inter-allelic crosses, using pyr-1 and col-4 as outside markers. Excluding a few exceptional crosses, the data give a linear order of the sites of the seven alleles within the gene, and confirm that allele 44204, previously assigned to a separate locus, pdx-2, is in fact an allele of pdx-1.