X ANIMAL COMMUNITIES 



work is based, that the survey aspect of ecology is a subject for co- 

 operative investigation. Because of the complexity of the problems, it 

 has been deemed advisable to publish this work even in its present 

 preliminary and necessarily incomplete form, in order to make the 

 material accessible as soon as possible to teachers, investigators, and 

 others who are interested. 



DEPARTMENT OF ZOOLOGY 



UNIVERSITY OF CHICAGO 



September 9, 1912 



