How was Ilya Ilyich Mechnikov awarded the Nobel Prize in Physiology or Medicine?

Name: Ilya Ilyich Mechnikov.
Country: Russia.
Date of Birth: 15 May 1845.
Died: 15 July 1916.
Education: Kharkov University, University of Giessen, University of Göttingen, University of Messina, University of Munich, University of Saint Petersburg.
Subjects Of Study: Phagocytosis.
Known as: Phagocytosis, Cell-mediated Immunity Gerontology.
Noble Prize Year: Nobel Prize for Peace in 1908, for his in recognition of their work on immunity.