

eee Tres oe 

VOLUME XXxI NUMBER 5 
DOTANICAL _CGAgerre 
MAY, rooz 
THE GENETIC DEVELOPMENT OF THE FORESTS OF 
NORTHERN MICHIGAN; A STUDY IN PHYSIO- 
GRAPHIC ECOLOGY. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
XVII. 
HARRY NICHOLS WHITFORD. 
(WITH EIGHTEEN FIGURES) 
Portions of the summers of 1898, 1899, and 1900 were spent 
by the writer in studying physiographic ecology at several 
points in northern Michigan. The work of the first two sum- 
mers was under the personal direction of Dr. H. C. Cowles, to 
whom the writer is indebted for many valuable suggestions. 
Indeed, the work set forth in the present paper is little more 
than the testing and working out in detail the ideas on physio- 
graphic ecology developed by Dr. Cowles in his lectures at The 
University of Chicago and in his published papers. Credit is 
due Mr. W. B. McCallum for the photographs used to illustrate 
this article, with the exception of figs. 7 and 4, which were 
obtained by Mr. E. N. Transeau. 
It should be clearly understood that the conclusions reached 
are based mainly on observations and are presented tentatively. 
They are published in the hope that they may be thoroughly 
tested by other observers, and if necessary modified or dis- 
carded altogether. It is the writer’s belief that only along lines 
Similar to those advocated here can the problems of forest dis- 
tribution be successfully solved. 
f 289 
