122 STRUCTUEE AND UNITS OF VEGETATION. 



species that is shown by formation and association is that of a division and 

 its subdivision. 



Negri's concept. — ^Negri (1914 : 33) has advanced a novel concept of forma- 

 tion and association, in accordance with which they become merely different 

 viewpoints of the same thing: 



"We term formation this vegetation considered in the complex of its bio- 

 logical relations, but not in its floristic composition; and understood in the 

 totality of its individuals and in all the secondary variations of composition, 

 of arrangement and of frequence, which it imdergoes during the persistence 

 of a physiographic unit of essentially unchanged edaphic conditions. (33) The 

 formation is the physiognomic and ecologic expression of the association, as the 

 biologic form is the physiognomic and ecologic expression of the species. (41) 

 To the formation — ^biologic term — corresponds exactly the association — floristic 

 term." (44) 



The adoption of this concept would result in the loss of the one point upon 

 which practically all ecologists are in agreement, namely, the subordinate 

 relation of the association to the formation. There can be no question of the 

 need of physiognomic, ecologic, and floristic viewpoints of the formation, but 

 their real values and significance appear only as they are considered in rela- 

 tion to development. The author's failure to understand the fundamental 

 nature of the formation as an organism with its own development is further 

 indicated by his comment upon climax formations. (42) While it is quite 

 possible to give the formation a different name for each of the four criteria, 

 viz, development, physiognomy, habitat, and floristic, it is clearly inadvisable 

 to do so. This is not merely because of the deluge of names that would result, 

 but especially because of intimate and often inextricable relations of these 

 four elements. 



Correlation of divergent views. — The extreme range of opinion as to the con- 

 cept of the formation is afforded by the views of Gradmann and of Warming. 

 The one would "ground formations solely upon floristic," the other expressly 

 states that the "formation is not concerned with floristic." Both clearly demon- 

 strate that a partial view is imfortunate, and serve to convince the open- 

 minded student that only the complete point of view, which includes all of the 

 relations of habitat and formation, is scientifically tenable. Every investigator 

 has been concerned primarily with one relation and has minimized or neglected 

 all the others. As a consequence, every standpoint has had its vigorous advo- 

 cates, with the result that their arguments have proven each other partly 

 right and partly wrong. It is clear why physiognomy as the most obvious 

 basis should have first dominated the concept, and why it should have been 

 displaced more and more by floristic. In both cases the habitat could not 

 well be completely ignored, but its real value could be appreciated only after 

 it began to be studied by means of instruments. Development is the most 

 recent phase of formational study, and has in consequence played little part 

 in determining the concept. The recognition of its fundamental rdle in no 

 wise minimizes the importance of the other viewpoints, since it is an epitome 

 of them all. It is also true that habitat, floristic, and physiognomy are com- 

 plementary and not antagonistic. A complete picture of the formation is 

 impossible without all of them, and the question of relative importance, if of 

 any consequence at aU, is a matter for much more detailed and thorough inves- 

 tigation than we have had up to the present. 



