CONCLUSION 303 



adapted in many different ways: various plant com- 

 munities, like plant-forms, may be adjusted with equal 

 efficiency to similar environments. The result is a certain 

 difficulty in bracketing together regions which from the 

 physical data at present available we may presume are 

 enjoying similar conditions, though the appearance of the 

 vegetation either in plant-forms or in communities may 

 be different. The evergreen, cool, temperate forests of the 

 Magellan and south Chilian coast region, and the moist 

 coniferous forests of the coast of British Columbia, are 

 a case in point ; again, the Argentine pampa and the 

 North- American prairie ; or, again, the eucalyptus park- 

 landscapes of the hinterland of eastern Australia and 

 the campos park-landscapes of the subtropical Brazilian 

 highlands. In many cases uncertainty arises simply 

 from the scarcity of reliable observations. In others, 

 however, the dissimilarity of plant-forms really conceals 

 a combination of different means making for an equivalent 

 adjustment to similar conditions. Only the study of the 

 modes of life and of the deeper-seated internal adapta- 

 tions discloses the identity of purpose and final adjust- 

 ment, the true homology of the plant-forms and com- 

 munities. 



It should also be borne in mind that the present plant 

 populations of the various parts of the world have arisen 

 from various sources, undergoing different processes of 

 development in the course of ages. Even though physical 

 conditions be equivalent at the present time on two 

 points of the world, the plant materials which had to 

 change and adjust themselves to these now identical 

 environments may have been originally different. It is 

 somewhat difficult, for instance, to understand why the 

 Pacific mountains of North America should be so over- 

 whelmingly populated with coniferous forests, without 



