3o8 Carl S\ottsberg 



are much more local. We must not think that the various con- 

 trivances by which diaspores might become dispersed are useless 

 or uninteresting simply because they do not accomplish trans- 

 oceanic dispersal. They are not only useful, but also necessary. 

 They enable a species to hold its ground and to reproduce within 

 its present area, and help it to colonize new soil within reason- 

 able distances. But as a rule they are not capable of gready ex- 

 tending the area of the species, so long as biotic and other con- 

 ditions remain unaltered, unless they are aided by man and his 

 traffic. He carries the seeds of species involuntarily to the re- 

 motest places, where they spring up and thrive under conditions 

 sometimes quite different. However, our experience does not 

 show that they change and become new species. 



The old Antarctic element in Polynesia, as represented in 

 Hawaii and the Marquesas, is particularly interesting when 

 affinity is not with Indomalaya-Australasia but with South 

 America, though subantarctic rather than neotropical. Acaena, 

 Astelia, Gunnera and, perhaps, Edwardsia, Oreobolus, and Co- 

 prosma have such affinities. A southeasterly road to Hawaii is 

 thereby suggested. I have never felt inclined to believe that this 

 affinity means floristic contact, but have preferred to think of 

 each of these stations as end stations for migrations from Ant- 

 arctica along either border of the Pacific. However, when all 

 along the western road there are no relatives of the Hawaiian 

 species, but such relatives are found in South America, we can- 

 not refuse to consider the possibility of a more direct route. If 

 there ever was such a road, its existence should perhaps be evi- 

 denced by the occurrence of a neotropical component in the 

 Polynesian flora. This component does exist. And it will be diffi- 

 cult to discover roads of communication other than across the 

 eastern Pacific. 



