Formation of asci with two diploid spores by diploid cells of Saccharomyces

Fifteen yeast strains that produced predominantly two-spored asci were found to include three strains having no more than two nuclei per ascus. The progeny of the spores of these three strains were capable of sporulation without conjugation. Deoxyribonucleic acid (DNA) determinations showed that both vegetative cells and spores were diploid, indicating that nuclear division in the ascus is not reductional.A structure present in the intersporal space of a two-spored strain was defined morphologically by electron microscopy.