Light micrograph of the freshwater alga Common stonewort (Chara vulgaris). At the cell of the filamentous main axis a female reproductive organ, the brownish coloured oogonium, can be seen, which is surrounded by helical cells. To the left below is the male reproductive organ, the orange coloured antheridium. Microscopic contrast method : dark field. Magnification 50x at a print width of 10 cm.