Differential interference contrast (DIC) light micrograph of a Spirogyra filament. The cell walls appear to glow due to birefringence, while a gelatinous outer membrane encases the entire filament. Within each cell, spiralling chloroplasts wind around the inner walls. The nuclei are distinctly visible, suspended in the centre of each cell, with microtubule filaments radiating outwards, connecting the nucleus to the interior cell walls. Magnification: x60 when printed with the longest axis at 10 centimetres long.