Theobald Smith (1859-1934) is widely considered to be America's first significant medical scientist and the world's leading comparative pathologist. Entering the new field of infectious diseases as a young medical graduate, his research in bacteriology, immunology, and parasitology produced many important and basic discoveries. His most significant accomplishment was proving for the first time that an infectious disease could be transmitted by an arthropod agent. He also made significant discoveries on anaphylaxis, vaccine production, bacterial variation and a host of other methods and...