6 



Nr. '.\. C. H. OSTENKIiLO: 



liii(|iiished whcii making coinparison with ol her areas, as 

 the data for species there lound have nol attained the same 

 device ol' precision, and there is Ihus a dander of lorming 

 eoncUisions which mav somclimes bc lar more misk'ading 

 Ihan Ihose hased on the larj^er specilic units. For before 

 \ve can make use of more speciaHsed knowledge of Ihc 

 forms (species) in a genus or group, il is nccessary tliat 

 they should have been investigated on Ihe same principles 

 throughout the entire area of distribution of Ihe genus or 

 group, as the case may be. This is a point very frequently 

 neglected in phytogeographical Nvorks. It has liappened, for 

 instance, Ihal the micro-species occurring in America have 

 been critically investigated, wilhout the same regard to the 

 micro-species occurring in other continents, and vice versa; 

 I am here thinking mostly of the colder parts of North 

 America and the corresponding portions of Asia and Europe, 

 which must necessarily be included in the investigation. 

 With these general observations in mind, \ve \\\\\ now 

 proceed to consider the Greenland flora and its origin. The 

 number of species, which, as will appear from the foregoing, 

 is somewhat arbitrary, amounts, in my estimation, to 390 

 phane^-ogams and pteridophytes for the whole of Greenland.^ 

 It is not a great number for so vast an exlent of terrilory. Hut 

 it must be borne in mind lliat Ihe whole interior of Green- 

 land is covered by ice, and liial the climate is unfavourahle 

 for vegetation both on account of the northerly situation and 

 the intense cold generated by Ihe mass of the inland ice 

 itself; finally also on account of the cold currents in the 

 surrounding seas. These three circumstances also parlly 

 account for the sliglil dillerence between the vegetation of 



' This does not includc fhe fcw species introdiiced diirii);^ flie past 

 two centuries tliroiij^li luiiiian a{»ency and partly acclinialiscd. 



