CONTENTS 



PAGE 



INTRODUCTION 1 



T. C. Chambeeliit, Universily of Chicago 



FIFTY YEARS OF DARWINISM 8 



Edwabd B. PotTLToir, Oxford University 

 THE THEORY OF NATURAL, SELECTION FROM 



THE STANDPOINT OF BOTANY .... 57 

 John M. Cotjlteb, University of Chicago 

 ISOLATION AS A FACTOR IN ORGANIC EVOLU- 

 TION 73 



David Stabr Jokdan, Stanford University 

 THE CELL IN RELATION TO HEREDITY AND 



EVOLUTION 92 



Edmttitd B. WiLsoir, Columbia University 

 THE DIRECT INFLUENCE OF ENVIRONMENT . 114 

 D. T. MacDottgaLj Carnage Institution of Wash- 

 ington 

 THE BEHAVIOR OP UNIT CHARACTERS IN 



HEREDITY 143 



W. E. Casiie, Harvard University 



MUTATION 160 



Chas. B. Daves-poet, Carnegie Institution of ^^ 

 Washington 



ADAPTATION 183 



Caei H. Eigenmanit, Indiana University 



DARWIN AND PALEONTOLOGY 309 



Henrt Fairfield Osbork, Columbia University 

 and American Museum of Natural History 



EVOLUTION AND PSYCHOLOGY 251 



G. Stanley Hall, Clark University 



