Mechnikov injecting a virus into a monkey at the Pasteur Institute. Ilya Ilyich Mechnikov (May 15, 1845 - July 15, 1916) was a Russian biologist best known for his pioneering research into the immune system, for which he won the Nobel Prize in Physiology or Medicine in 1908. He discovered phagocytosis while working at a private laboratory in Messina, Sicily where he was studying comparative embryology on the larvae of starfish. Phagocytosis is the process of cells engulfing large particles (such as bacteria or dead cells), and one of the ways that the white blood cells of the immune system fight disease. He is credited by with coining the term gerontology in 1903, for the emerging study of aging and longevity. He worked with ?mile Roux on calomel, an ointment to prevent people from contracting syphilis, a sexually transmitted disease. He died in 1916 from heart failure.