Mitosis and Cytokinesis in Coleochaete Scutata¹

SUMMARY Increase in the size of thalli of C. scutata was achieved by division and growth of the marginal cells. During mitosis, the nuclear envelope disintegrated and the daughter nuclei remained widely separated after telophase. The plane of cytokinesis in the marginal cells was either along a radius of the discoidal thalli or parallel to their circumference For radial divisions, this alga utilized a phragmoplast typical of higher plants, and a modified phragmoplast when dividing circumferentially. The phylogenetic implications of these findings are discussed.