The Flora of Greenland and its Origin. 9 



nearer North America, but has, however, such peculiarities 

 that it must be regarded as a separate entity." 



In the French summary of the above work (p. 245) 

 Warming says more definitely: "ce n'est pas le détroit de 

 Davis — comme Hooker l'a supposé — mais plutot le 

 détroit de Danemark, entre le Groenland et l'Islande, qui 

 forme la ligne de separation entre la flore européenne et 

 la flore americaine." 



This view was strongly opposed by the Swedish botanist 

 and geologist A. G. Nathorst (1890). From the absence of 

 western types in East Greenland between 63° — 66° N. Lat., 

 we should, in his opinion, draw the dividing line between 

 American and European flora there, so that the inland ice, 

 and not Danmark Slrait, should form the actual boundary; 

 furthermore, by far the greater part of the flora must have im- 

 migrated, since the glacial period, to West Greenland from 

 North America, which view was supported by the faet that 

 the western types are most numerous in West Greenland 

 between 64° and 69° N. Lat, where the distance to America 

 is least (except for the far north); the flora of East Greenland 

 had probably immigrated via some postglacial land connec- 

 tion with Iceland. 



Nathorst's criticism at once (1890) elicited a sharp 

 retort from Warming, who rightly pointed out, inter alia, 

 that it was a remarkable method of proceeding, to take as 

 the crucial point of the proof an area (East Greenland 63° — 

 66° N, Lat.) from which [at that time] hardly any piants 

 were known at all. Warming also drew attention here to 

 the probable importance of the ancient Norse colonisation 

 as a factor in the development of the South Greenland 

 flora. The discussion closed with a further sharp reply 

 from Nathorst (1891) with the result that the two old 



I 



ff^. 



