356 THE CANADIAN NATURALIST. [June 



The proportion formerly deduced by Brown, etc., for the high 

 arctic regions was a much smaller one ; the Monocotyledons being 

 in comparison with the Dicotyledons 1:5; and this still holds for 

 some isolated, very arctic localities, as North-east Greenland; 

 whereas Spitsbergen presents the same proportion as all the 

 arctic regions, 1 : 2-7 ; the Parry Islands, 1 : 2-3 ; the west coast 

 of Baffin's Bay, from Pond Bay to Home Bay, 1 : 3-3; and the 

 extreme arctic plants mentioned at p. 333, 1:3. Of the preva- 

 lent arctic plants mentioned at p. 332, the proportion is 1 : 3-4. 



I have dwelt more at length on these numerical proportions 

 than their slight importance seems to require ; my object being to 

 show how little mutual dependence there is amongst the arctic 

 florulas. Each has profited but little through contiguity with its 

 coterminous districts, though all bear the impress of being 

 members of one northern flora. 



V. ON GROUPING THE FORMS, VARIETIES, AND SPECIES OF 



ARCTIC PLANTS FOR PURPOSES OF COMPARATIVE STUDY. 



Considering the limited extent of the arctic zone, the poverty of 

 its flora, which is almost confined to 14° of latitude in the longi- 

 tudes most favorable to vegetation, and to only 10° in the Asiatic 

 area, and the number of able botanists who have studied it, it 

 might be supposed that the preliminary task of identifying the 

 species, and tracing their distribution within and beyond the 

 arctic circle would have been short and simple ; but this is not the 

 case ; for owing to the number of local floras, voyages, travels, and 

 scientific periodicals that have to be consulted, to the variability 

 of the species, and the consequent difficulty of settling their limits, 

 and to the impossibility of reconciling the divergent opinions of 

 my predecessors regarding them, I have found this a very tedious 

 and unsatisfactory operation. 



Of all these sources of doubt and error, the most perplexing 

 has been the well-known variability of polar plants ; and in the 

 existing state of the controversy upon Mr. Darwin's hypothesis, 

 it requires to be treated circumspectly. In several genera I have 

 not only had to decide whether to unite for purposes of distribu- 

 tion dubious or spurious arctic species, but also how far I should 

 go in examining and uniting cognate forms from other countries, 

 which, if included, would materially aflect the distribution of 

 the species. These questions became in many instances so numer- 

 ous and complicated, that I have often resorted to the plan of 



