6 BIG SPRING PRAIRIE. 



The writer wishes to extend his thanks to Dr. H. C. 

 Cowles, of the University of Chicago, under whose direc- 

 tion the investigation of this area was conducted: and 

 also to Prof, W. A. Kellerman, Ph. D., of the Ohio State 

 University, for some of the photographs, and for his per- 

 sonal visits to the area and his kind assistance in various 

 ways. The writer is also under obligation to Mr. W. 

 C Johnson, Mr. Peter Brayton, and Mr. H. B. Phelps 

 for aid rendered or information furnished. 



The principal factors which must be considered in 

 prosecuting the lines of investigation indicated naturally 

 divide themselves into Climatic, Physiographic, His- 

 torical, and Ecological. 



