Chemotherapy is the treatment of a disease or condition with chemicals that have a specific effect on its cause, such as a microorganism or cancer cell. The first modern therapeutic chemical was derived from a synthetic dye. The sulfonamide drugs developed in the 1930s, penicillin and other antibiotics of the 1940s, hormones in the 1950s, and more recent drugs that interfere with cancer cell metabolism and reproduction have all been part of the chemotherapeutic arsenal. _{Bacterial infections}For thousands of years, medical practitioners have used plants and other substances to treat symptoms of disease. Modern chemotherapy began with the German physician Paul Ehrlich, who as early as 1905 began looking for specific chemicals to be "magic bullets" seeking out and destroying infectious organisms within the body without harming healthy tissues. In 1910, Ehrlich discovered that an arsenic compound he had named Salvarsan was successful in treating the sexually transmitted disease...