Phagocytosis

In 1882 in Messina (Italy), while studying starfish larvae, Mechnikov observed how certain cells surrounded and engulfed foreign particles — rose thorns he had inserted into a larva. He named these cells 'phagocytes' (from Greek φαγεῖν — to devour and κύτος — cell). This observation became the foundation for the phagocytic theory of immunity, which explained one of the key mechanisms of the body's defense against infections. The discovery was so revolutionary that it initially met resistance from many scientists, particularly supporters of the humoral theory of immunity. However, over time, the phagocytic theory gained recognition and brought Mechnikov the 1908 Nobel Prize.