1918] CURRENT LITERATURE 387 
himself claims that the scheme is the outgrowth of the classification originally 
presented by Cow Les,” and by his selection of the association as the funda- 
mental unit of vegetation he recognizes the tendency of ecologists as a whole 
to become more and more agreed upon the use of the term “plant association,” 
even while differing somewhat as to the content of the term. He defines the 
association as any community of plants, taken in its entirety, which occupies 
a common habitat, or in other terms, any stage in a given successional series. 
The “‘habitat,’”’ thus made the criterion of the association, is understood to be 
a unit area with an essentially uniform environment made up of a complex of 
climatic, edaphic, and biotic factors which determine the ecological aspect 
of the vegetation. The subdivisions of the association agree with those of 
CLEMENTs in being consociation and society, but differ in that ‘‘association”’ 
(and its subdivisions) is applied to both the climax and the seral units 
N. h 
ecologists recognizing this situation have preferred to regard such associations 
as belonging to a “‘temporary climax,” postulating the oo although much 
delayed dominance of a climax limited by climate o 
Grouping plant associations upon a developmental basis, the plant com- 
munity of the next higher order is termed an “edaphic formation” and defined 
as “‘an association-complex which is related to a specific phys: iographic unit 
concepts to include the developmental idea. The various climatic formations 
long to various “climatic formation-types,”’ several of which may form the 
“climatic formation-complex”’ of a continent or other large unit area. 
Nicuots has further demonstrated the utility of his excellent scheme of 
classification by applying it to the analysis of the vegetation of northern Cape 
* Cowes, H. -C., se a ecology of Chicago and vicinity. Bor. 
Gaz. 31: ne, 145-235. 
