In this incisive book, a distinguished geneticist has succeeded in relating the extraordinary biological discoveries of the last two decades to the basic questions about the origin and evolution of life on earth. The "molecular revolution" in biology--culminating in the discovery of the relations of the giant molecules of living matter--the operation of the genetic code, and the relational order in the biological world are all considered. Originally published in 1969. A UNC Press Enduring Edition -- UNC Press Enduring Editions use the latest in digital technology to make available again books from our distinguished backlist that were previously out of print. These editions are published unaltered from the original, and are presented in affordable paperback formats, bringing readers both historical and cultural value.