VOL. XLV, NO. 537 



SEPTEMBER, 1911 



THE 



AMERICAN 

 NATURALIST 



A MONTHLY JOURNAL 

 Devoted to the Advancement of the Biological Sciences 1 

 Special Reference to the Factors of Evolution 



THE SCIENCE PRESS 

 LANCASTER, PA. OAKWSON, K. T. 



HEW YORK : SUB-STATION M 



