Processes of organic evolution / G. Ledyard Stebbins. Stebbins, G. Ledyard (George Ledyard) 1906-2000. Evolution (Biology) QH366 .S82 575 STP Includes bibliographical references and index. Englewood Cliffs, N.J. : Prentice-Hall; 1966. 1966. 1966 Text xii, 191 p. : eng Concepts of modern biology series ;