148 ADAPTATIONS. OECOLOGICAL CLASSIFICATION 



communities as a whole.^ But it does not seem possible to use develop- 

 ment as the fundamental basis of classification of plant-communities : 

 for developmental changes are too dependent upon local conditions ; 

 a formation does not develop merely in a single definite direction, but 

 wiU modify in one direction at one place and in another at another place, 

 according to the prevaiUng conditions .^ 



' As regards Denmark see Warming, 1904, 1906, 1907-9. 



' Concerning the oecological nomenclature and classification see : G. Beck von 

 Mannagetta, 1902 ; Brockmann-Jerosch, 1907 ; Cajander, 1903 ; F. Clements, 

 1902, 1904, 1905 ; Cockayne, loc. cit., 1905 ; Cowles, 1899, 1901 ; Drude, 1896, 1905 ; 

 Flahault, 1900, 1901 ; Ganong, 1902; Grabner, 1905, 1898 a, 1909; Harshberger, 

 1900, &c. ; Kearney, 1900; Kerner, 1891 ; A. Nilsson, 1902; Kirchner und Schroter, 

 1 896-1902; Shantz, 1905; R. and W. G. Smith, 1898, 1899, &c, ; Stebler and 

 Volkart, 1 904 ; Woodhead, 1 906. 



