This illustration shows the colonial forms of unicellular green algae: A, Pediastrum, the plants of the colony being arranged in a flat plate. B, a view of the outer cells of the colony showing the formation of a new colony. C, one of these new colonies. D, a plant of the water net containing a young colony. E, enlarged view of one of the meshes of a net showing the geometrical arrangement of the plants.
Carlton C. Curtis, Nature and Development of Plants (New York: Henry Holt Company) 184