CONCLUSION 395 



continental drift, or of the possibility of an expanding earth crust as mentioned 

 by Heezen and Tharp (this symposium; cf. also Dicke, 1962). 



A geological question of utmost importance for the ultimate solutions of 

 many problems here discussed concerns detailed examination of the Hgnites 

 of the North Atlantic basalt formation, which reaches from Scotland and 

 Northern Ireland to the Faeroes, Iceland, and Greenland (cf. Tr. Einarsson, 

 Rasmussen, this symposium). Only such a study can clarify the particulars of 

 the geological and chmatological history of hfe in this part of the world 

 during the Tertiary. Still, these hgnites are very sporadically known. As a direct 

 continuation of such studies of the lignites ought to follow detailed investiga- 

 tions of the Icelandic Pleistocene deposits and of Late Glacial and Post- 

 Glacial palynological phenomena in all the countries concerned. 



Turning to the biological field, palynological identifications of all the species 

 of the North Atlantic flora is both desirable and essential for the interpreta- 

 tion of past dispersal and distribution areas. Such a background may help in 

 understanding the formation of the hmits between the Arctic and Subarctic 

 discussed by Bocher (this symposium). It could probably also find explanation 

 of the pecuhar disappearance and reappearance of the vegetation zonation 

 discussed by Sjors (this symposium), and support or contradict the hypothesis 

 of dispersal of plant communities rather than of individual diaspores as 

 suggested by Hadac (this symposium). Palynology can also be expected to in- 

 crease our understanding of the importance of the conservative statocrats and 

 the aggressive apocrats (cf. Erdtman, this symposium) in the history of the 

 floras concerned. A combined palynological and cytotaxonomical study based 

 on this concept is also likely to provide new ideas for an explanation of the fact 

 that the frequency of polyploids increases with an increased latitude and is 

 highest in the areas where we expect the highest frequency of glacial survivors 

 (Love, 1953, 1959; Love and Love, 1949, 1957; Reese, 1958, 1961a, b; 

 Favarger, 1961). 



Though the general knowledge of the botanical and zoological conditions 

 in the North Atlantic countries is better than almost anywhere else, studies on 

 distribution and sociological behavior still remain insufficient in parts of the 

 area, and the taxonomy of many species is often incomplete and inexact. 

 Detailed studies on minor races need to be intensified, as demonstrated by the 

 excellent results achieved by Nordhagen (1931, 1935) and Nannfeldt (1935, 

 1940). In addition, the problem of endemism needs special attention by 

 cytogeneticists (cf. Love and Love, 1956, 1961). The universally accepted 

 idea that the frequency of endemics should reflect the age of a flora or fauna 

 is still not completely confirmed, at least not in northern lands where popula- 

 tions are medium-sized and competition is limited. Some of the more widely 

 distributed North Atlantic endemics, e.g. Armeria maritima ssp. planifolia, 

 Geum rivale ssp. islandicum, and Papaver Nordhagenianum ssp. faeroeense. 



