Curare is an arrow-poison used by South American Indian hunters, extracted from various plants, chiefly of the genera Strychnos and Chondrodendron, killing by respiratory paralysis. Curare is a mixture of alkaloids, the chief being d-tubocuranine. By competing with acetylcholine it blocks the transmission of nerve impulses to muscles, producing relaxation and paralysis. Curare has revolutionized modern surgery by producing complete relaxation without a dangerous degree of anesthesia being required. See also tetanus.