THE PRIMARY FACTORS 



ORGANIC EVOLUTION 



E. D. COPE, PH. D. 



MEMBER OF THE U. S. NATIONAL ACADEMY OF SCIENCES; PROFESSOR 



OF ZOOLOGY AND COMPARATIVE ANATOMY IN THE 



UNIVERSITY OF PENNSYLVANIA 



CHICAGO 



THE OPEN COURT PUBLISHING COMPANY 



(LONDON: 17 JOHNSON'S COURT, FLEET ST., E. C.) 



1904 



