Light micrograph of the freshwater green alga Cosmarium amoenum. Cosmarium belongs to the family Desmidiaceae. They are unicellular, unflagellated cells whose cells are divided into two symmetrical half-cells by a central incision. Each half cell has one or two axial chloroplasts with pyrenoids. Culture material of the algae collection at the University of Cologne (CCAC). Microscopic contrast method : Differential interference contrast. Magnification 920x at a print width of 10 cm.