Light micrograph of Hydrodictyon sp. , a freshwater green algae also known as the water-net. A colonial algae, each individual cylindrical cell typically connects with 6 neighbours (5-8 are also known) to form a hexagonal meshwork over the surface of water. Hydrodictyon is a coenobium or determinate colony, the total number of divisions & thus the number of cells making up the colony is fixed at the time of the origin of the colony & cannot be extended. Unlike indeterminate colonies, it is not simply an aggregate of cells with unlimited potential for cell division. Rheinberg illumination, magnification: x 175 at 35mm size. Ref. MICROCOSMOS, figure 5.25, page 101