YOl. XI VI, HO. 649 



SEPTEMBER, 1912 



THE 



AMERICAN 

 NATURALIST 



A MONTHLY JOURNAL 

 Devoted to the Advancement of the Biological Sciencei with 

 Special Reference to the Factors of Evolution 



CONTENTS 



Mortality with Respect to Seed Weight occurring in Field 

 Polymorphism in Asplanchna simulating Mutation. Professor J . 



Professor Charles W. Hakgitt - 



irley's Breeding Ex 



THE SCIENCE PRESS 

 LANCASTER, PA. GARRISON, H. T. 



NEW YORK : SITB-STATION 84 



