Paul Ehrlich (March 14, 1854 August 20, 1915) was a German scientist who won the 1908 Nobel Prize in Physiology or Medicine. He is noted for his work in hematology, immunology, and chemotherapy. Ehrlich predicted autoimmunity and called it "horror autotoxicus". He coined the term "chemotherapy". The idea of a "magic bullet" is also his, and he is credited with the first empirical observation of the blood-brain barrier.