a genus of microscopic unicellular green algae of the class Protococcophyceae. The cells, which are spherical or ellipsoid and contained in a cellulose envelope, may have one parietal chloroplast with a pyrenoid or no chloroplast and one nucleus. The organisms store starch and oil. They reproduce by means of autospores. The USSR has about ten species, which are distributed throughout the country. They are cultivated on a wide scale as a possible source of food and fodder, for the biological purification of sewage, and for the regeneration of air in closed ecosystems, for example, in spaceships and submarines.