In 1882 Ilya Mechnikov, Russian biologist, discovered phagocytosis - a phenomenon of active grasp and uptake of living and lifeless particles by special cells (phagocytes) of multicellular organisms. Phagocytosis takes part in organism defense against infection, supports function of immune system, participates in inflammation and in wound repair. Press the "Start" button. Larva of starfish is picked by thorn of rose, which is contaminated by lifeless particles and bacteria. A wound is surrounded by phagocytes. They attach to bacteria, cover and uptake them finally forming an intracellular corpuscle - phagosome. To digest the particle hydrolytic enzymes from lysosomes are transferred into phagosomes. In dependence on the kind of the particle and feature of phagocyte the digestion may be complete or incomplete. The animation is operated by the "Stop" and the "Reset" buttons. In human and mammalians the function of phagocytes is performed by spatial blood leucocytes (neutrophils) which digest small particles (including bacteria) and macrophages which uptakes the large particles like dead cells or parts of the cells. It is supposed that initially the phagocytosis was developing on the basis of the ability of unicellular organisms to uptake food. Mechnikov has shown in which way this ability was gradually transformed into the mechanism of protection during evolution.