Phagocytosis. Coloured scanning electron micrograph of a polymorphonuclear white blood cell or leucocyte, attacking Bacillus cereus bacteria. The leucocyte (orange), part of the body's immune system, is attaching to and engulfing the Bacillus cells (blue, rod- shaped). It uses enzymes to digest the bacteria. This process of engulfment and digestion is known as phagocytosis. Highly mobile, phagocytic cells migrate to areas of tissue damage. However, their necessary enzymes are quickly depleted by phagocytic activity so they degenerate. Defunct cells accumulate in pus. Magnification x7,300 at 6x7cm size. Magnification: x25,000 at 10x8 size."