Book excerpt: A surprising number of Americans were involved with the so-called Dark Continent during the period when Western penetration led to conquest and colonial rule. The six Americans discussed are: Thomas Jefferson Bowen, who established the first American mission posts in Yorubaland; writer-explorer Paul du Chaillu; soldier-explorer Charles Chaille-Long; diplomat Henry Shelton Sanford; mining engineer John Hays Hammond; and taxidermist Carl Akeley. Illustrated.