CONDITIONS ON WHICH DISTRIBUTION DEPENb. $ 



to 55. France is therefore unquestionably richer in species 

 than Lapland. 



' But the matter stands in a somewhat different light 

 when we consider these plants in relation to the total 

 vegetation of the two countries ; and since it is by this 

 means we come to comprehend the characteristic of the 

 region of vegetation, we can only allow this mode of consid- 

 eration to be valid. Now France possesses altogether about 

 4,500 phanerogamous plants, and the sedges constitute only 

 l-27th of these; the phanerogamia of Lapland are confined 

 to some 500 species, and l-9th of these are sedges. The 

 sedges are therefore a much more essential part of the 

 Lapponic flora than of the French, the former having a 

 relatively larger number of species than the latter. And 

 this it is alone that is understood by the increase of 

 species in a given direction.' 



