Chimeras on the Horizon, But Don't Expect Centaurs.

Discusses chimeras, creatures composed of more than one kind of cell. Observation that mythology is populated with half-human chimeras; Types of chimeras that biologists have been generating for years; The promise of embryonic stem cells; Why chimeras grip the imagination; Views of biologists; Ethics of chimera manufacture; Cases in which human-animal chimeras could raise awkward issues; Topic of nuclear transfers; Outlook for creating a viable chimeric creature; Guidelines that were proposed by the National Academy of Sciences.