These essays examine the developments in three fundamental biological disciplines--embryology, evolutionary biology, and genetics. These disciplines were in conflict for much of the 20th century and the essays in this collection examine key methodological problems within these disciplines and the difficulties faced in overcoming the conflicts between them. Burian skillfully weaves together historical appreciation of the settings within which scientists work, substantial knowledge of the biological problems at stake and the methodological and philosophical issues faced in integrating biological knowledge drawn from disparate sources.