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grow." This master in the study of plant geography recognizes, 
but does not specifically define, ecology. The passage quoted 
above is the epitome of Meyen's idea of ecology, and his treat- 
ment of it is mostly physiographic and edaphic. He thinks and 
writes of plant ecology in terms denoting unmistakably that the 
relation of plants en masse to their environment is, to him, the 
crux of the question. 
Warming, the father of modern plant ecology, delimited the 
concept thus, in 1895: Ecology “teaches us how plants or 
plant communities adjust their forms and modes of behavior 
to actually operating factors, such as the amounts of available 
water, heat, light, nutriment, and so forth." This landmark in 
the development of the science is almost exclusively physiographic 
in its scope, and throughout it is the relation of plants en masse, 
and plant communities, to their environment that is considered 
fundamental. That these "actually operating factors" must, 
of course, operate on individuals, in order to have the least effect 
upon the distribution of collections of plants, was fully recognized 
by the author. 
He did not, however, consider these purely physiologic and 
morphologic adaptations of individuals as the principal feature 
of ecology, for his book is mainly a descriptive study of vegetation. 
In this country, one of the first to use the term and the first to 
make a serious contribution to the science, was MacMillan. 
During 1897, in his Minnesota Botanical Studies, which were 
wholly physiographic in character, he says: ‘‘That branch of 
biology which concerns itself with the adaptation of organisms to 
their surroundings, is . . . termed ecology." His Metaspermae 
of the Minnesota Valley marks the beginning of a voluminous 
literature of a distinctly ecological trend, notwithstanding the 
fact that this particular work was phytogeographical, which is 
quite another thing. That MacMillan, in most of his writings, 
was an ecological plant geographer and that the distribution of 
plants en masse was the chief interest with him, is the only con- 
clusion that forces itself on his numerous readers. 
We have, then, still with us in 1897, the word ecology, which, if 
not actually, had by usage become a symbol of a rather definite 
idea, almost exclusively physiographic in scope. 
