Ilya Illich Mechnikov (1845 - 1916), Russian zoologist and bacteriologist. He investigated intracellular digestion; formulated the theory of phagocytosis (the ingestion and destruction of cells, microorganisms, or other foreign matter in the blood by cells capable of surrounding, engulfing and digesting bacteria and viruses) and made microscopic studies of diseases of the blood. —PDC Volume 4 Approved Glossary