Differential interference contrast (DIC) light micrograph of the freshwater alga Volvox aureus. Volvox forms large (up to 2 millimetres), spherical colonies with up to several thousand two-flagellated single cells arranged in a regular pattern in the periphery of a colourless jelly. This is an adult colony with the single algae cells connected with plasma bridges. The colony is infected by parasitic amoebae, one is in the middle of the image, at right one of the algal cells has been ingested by these amoebae. Magnification: x670 at a print width of 10 centimetres.