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Igor] PHYSIOGRAPHIC ECOLOGY OF CHICAGO 85 
the theory to the most rigid test possible. In connection with 
a number of students, investigations have been carried on about 
Chicago, in northern Michigan, in Tennessee, and along the 
Atlantic coast. In all cases it’ has been possible to find a 
general consonance between the facts of distribution. and the 
principles as stated above. The theory has suffered many modi- 
fications since its first conception, and doubtless it will suffer 
more. Indeed, it may be discarded altogether for.some other 
better theory. Nevertheless, publication at this time seems to 
be justified, and it is hoped that this paper may aid in solving 
some of the riddles of ecology. 
The author especially wishes to mention in this place the 
work of his student and associate, Mr. H. N. Whitford, who has 
in preparation a physiographic study of the forests of north- 
ern Michigan. The author is likewise especially indebted to 
another of his students, Mr. W. B. McCallum, who has taken all 
of the photographs with which this paper is illustrated, with the 
exception of figs. 7 and 73, which were contributed by Professor 
J. J. Allison, of Joliet. Acknowledgment should also be made 
of the help given by three excellent papers which deal with 
the general physiographic and geographic features of the Chi- 
cCagoarea. To these works by Leverett, Blatchley,” and Salis- 
bury and Alden* the author has made constant reference. The 
author has likewise freely used the work of Higley and Raddin.” 
In the following pages the various series of the Chicago area 
are discussed in some detail. Two general groups are made; 
the inland and the coastal. The inland group is subdivided into 
three series, river, swamp, and upland. The coastal group is 
eccanione into two series, lake bluff and dune. The river series 
ERETT, F.: The Pleistocene features and eo of the Chicago area, 
Chica or 
7 BLAT LEY, W. S.: The geology of Lake and Porter counties, Indiana. 
tae fron ie Twenty-second Annual Report of the Department of Geology and 
Natural Resources of Indiana. Indianapolis, 1 1897. 
* SALIsBuRY, R. D., and ALDEN, W. C.: The geography of Chicago and its 
environs. Chicago, 1899. 
*“ HIGLEY, W. K., and RAppIN, C. S.: The flora of Cook county, Illinois, and a 
part of Lake county, judas Chicago; 1891. 
