How was Paul Ehrlich awarded the Noble Prize in Physiology or Medicine?

Name: Paul Ehrlich.
Country: Germany.
Date of Birth: 14 March 1854.
Died: 20 August 1915.
Education: University of Göttingen.
Subjects Of Study: Antiserum, Chemotherapy Hematology Side-chain theory Syphilis.
Known as: Chemotherapy, Immunology, Basophil, Magic bullet, Mast cell, Receptor theory, Side-chain theory, and Ehrlich’s reagent.
Noble Prize Year: Nobel Prize for Peace in 1908, for his in recognition of their work on immunity.