Douglas "Jocko" Henderson ranks with Daddy O' Daylie and Hot Rod Hulbert as one of the original rhythm and blues radio disc jockeys. His smooth, swinging, rhymed talkovers were imitated by the jocks of the early rock and roll era, and became one of the major sources for the rap style. Though his influence on hip-hop was crucial, it took an indirect route as the model for the toasts of early Jamaican sound system deejays. Some say that Jocko's syndicated radio shows...