Anthrax, a disease of animals and humans, is caused by an aerobic, spore-forming, Gram-positive rod—Bacillus anthracis. Some of the more common synonyms are charbon, malignant pustule, malignant carbuncle, milzbrand, splenic fever, and woolsorter’s disease. This organism is not only important to the present-day livestock industry and to certain occupationally exposed humans; B. anthracis also holds a special historical niche in the development of modern-day bacteriology, immunology, and knowledge of infectious diseases.