Apart from the previously studied g-locus, the i-locus showed the following characteristics. I. One-point cross conversion frequencies were roughly constant around 10×10^-3, unless associated with a Rec⁺ factor. II. The interallelic conversion frequencies were either the sum of parental one-point cross conversion frequencies (20×10^-3) or still higher than this, suggesting that this locus has compound composition with at least two units. III. Whenever interallelic cross conversion frequency was notably higher than 20 ×10^-3, the ascus frequency of the spore colour ratio, 2+, 2i, 4b (asci of this composition can be developed through gene conversion or appear as tetratypes through reciprocal recombination) was high enough to include the excess portion of the conversion frequency, leaving substantial surplus. This suggests that the i-locus is composed of multiple units, and at the joints of units ordinary reciprocal cross-overs occur producing tetratype asci; and cosequently raising the apparent conversion frequencies. IV. The original blu₆allele was accompanied with a Rec⁺ factor, and therefore, its conversion frequency was low. Through gene conversion, this factor was removed from blu₆ and transferred to the wild type allele. V. The Rec factor functions as a mutator on the alleles in the i-locus, and by itself, it was labile. Among the above characteristics, III and V respectively show close relationships with the compound genes of Neurospora and the mutable genes of Zea.