Flahault : Phytogeographic Nomenclature 395 



Thenceforth, the fundamental climatic zones divide naturally 

 into large natural regions of vegetation. When studying the flora 

 of the world, this division is the most apparent, and it is the most 

 important. The great regions of vegetation are great climatic 

 regions ; the map of the distribution of large natural groups coin- 

 cides with the principal types of climate over the whole earth. 



Martius was the first to distinguish regions (Florenreiche).* 

 A. de Candolle defined them with more precision, f The name 

 has been generally adopted ; there is then reason to follow tradi- 

 tion. A more or less broad sense has been attributed to it. We 

 think it would be expedient to give it the import which was attributed 

 to it by Grisebach in his principal work. % The vegetative regions 

 of Prof. Drude are the same. § So we say the Forest region of 

 northern Eurasia, the Temperate forest region of western Europe, 

 Mediterranean region, Eurasiatic steppe region. This is the proper 

 meaning of the word in French ; it expresses above everything a 

 " large extent of country" (Littre). The great mountain masses 

 considered as a whole and in their relations to the regions 

 which surround them and to the entire terrestrial surface may also 

 constitute natural regions. The entire group of the Alps consti- 

 tutes the Region of the Alps ; the Region of the Caucasus is dis- 

 tinguished in the same way, also that of the Pyrenees, the Iberian 

 group and of the Balkans. It will be a question if, according 

 to their relative importance and the relation of their vegetation 

 to that of adjoining units, mountain groups of less importance 

 should have the value of different subordinate units. So that 

 we would say : the domain of the central group of France, 

 domain of the Jura, austro-occidental domains, the central and 

 eastern of the Alps ; that we distinguish eastern, central and west- 

 ern sectors of the Pyrenees, the Savoie, Dauphine, Provencal and 

 Maritimes sectors of the Alps, the districts of the Alberes, the 

 Causses and the granitic Cevennes, etc. 



The different strata of vegetation which range in echelon over 

 the declivities add a certain number of questions to those which 



* Von Martius, Historia Natur. Palmarum, I: tab. geogr. III. and IV., 1831. 

 t A. de Candolle, Introduction Geogr. bot., 1837. 

 % Grisebach, La Vegetation du Globe. 

 \ Drude, Manuel, p. 302. 



