
VOLUME XXxXI1 NUMBER 2 
DOTANICAL (Gee 1 e 
FEBRUARY, 1901 
THE PHYSIOGRAPHIC ECOLOGY OF CHICAGO AND 
VICINITY; A STUDY OF THE ORIGIN, DEVELOP- 
MENT, AND CLASSIFICATION OF PLANT SOCIE- 
gy 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
HENRY CHANDLER COWLES. 
(WITH THIRTY-FIVE FIGURES.) 
I. The content and scope of physiographic ecology. 
Wirun the last few years the subject of ecology has come to 
find a place of more or less importance wherever botany is 
Studied in its general aspects. The limits of the subject, how- 
ever, have not yet been defined, nor have many attempts been 
made to bring order out of the chaos which exists with regard 
to the arrangement of the subject-matter. Thé main purpose 
of the present paper is to suggest a classification of a portion of 
the ecological field. 
Whatever its limits may be, ecology i is essentially a study of 
origins and life histories, having two well-marked phases; one 
phase is concerned with the. origin and development of plant 
structures, the other with the origin and development of plant 
Societies or formations. The plant structure side again has two 
aspects, one viewing organs or plant forms as a whole, the other 
viewing the tissues which make up the organs; the former might 
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