Nuclear Behavior in the Basidia of the Secondarily Homothallic Coprinus bilanatus

Nuclear behavior in the basidia of the secondarily homothallic basidiomycete Coprinus bilanatus was studied with light microscopy. This two-spored species was found to be similar in many respects to Agaricus bisporus and the four-spored species C. cinereus. The major point of variation was in the timing of the movement of the four meiotic products into the developing basidiospores. In the strain of C. bilanatus used here the spores are full sized and heavily pigmented before nuclei move into them. Two nuclei enter each spore. The apical to basal movements of post-meiotic nuclei reported here suggest that the alignment of the spindles at meiosis II may not be a significant factor in the entry of nuclei into specific spores.