1. In tetraploid maize unimodal curves were obtained from hybrids between self-fertile and self-sterile lines back-crossed to the self-fertile parent; in the back-cross to the self-sterile parent a bimodal ourve was obtained, 250 or more individuals being involved in each population. In the F2 population of the same crosses unimodal or very weakly bimodal curves were obtained.

The F1 of the incompatible matings between the self compatible lines (B lg and su) of tetraploid maize reported in the last News Letter was found to be self-fertile, and the back-crosses to the parent lines were also compatible, as indicated by observations on 50 or more ears from each cross. An incompatible mating between the cross-sterile B Lg line and a self-sterile B line showed an intermediate degree of self-fertility (37%) in F1. The backcross to the B lg parent was 37% compatible (28 ears) while the back-cross to the B Lg parent was only 15 percent compatible.

Harold E. Fischer