AN OUTLINE OF THE THEORY 



OF 



ORGANIC EVOLUTION 



WITH A DESCRIPTION OF SOME OF THE 

 PHENOMENA WHICH IT EXPLAINS 



BY 



MAYNARD M. ^METCALF, PH.D. 



PROFESSOR OF BIOLOGY IN THE WOMAN'S COLLEGE OF BALTIMORE 



r \ 



SECOND EDITION 

 REVISED 



gorfc 

 THE MACMILLAN COMPANY 



LONDON: MACMILLAN & CO., LTD. 

 1906 



All rights reserved 



