Abstract
Twenty isoleucine and valine requiring mutants including a temperature mutant were found to be separable into three groups genetically, I, II and III. The mutants are located at sites distal to lysine-1 and proximal to spray in linkage group V in the order III, II and I. This arrangement of the groups is of particular interest when considered in conjunction with the biochemical characteristics of the mutants.
Certain unexpected ratios of recombinants with respect to outside markers are noted and discussed. In addition selfing crosses are described some of which resulted in a high frequency of progeny with a wild phenotype.
