Production of Hybrids between Physiological Races of the True Slime Mould Didymium iridis

Abstract

FOR many years it was believed that plasmodia of the same species of Myxomycetes merge on contact, whereas those of different species do not. This test was proposed as a criterion of specificity by Torrend1 in 1909. In 1934 Skupienski2 announced the discovery of physiological races in Didymium iridis (D. xanthopus) and stated that the plasmodia of the two races he had in culture would not merge. Later he found3 physiological races in Didymium squamulosum, and Gray found them in Physarum polycephalum4.