522 ISLAND LIFE tart ii 



group of large islands probably extends across or around the 

 south polar area to Victoria Land and thence to Adelie 

 Land. The outlying Young Island, 12,000 feet high, is 

 about 750 miles south of the Macquarie Islands, which 

 may be considered a southern outlier of the New Zealand 

 group ; and the Macquarie Islands are about the same 

 distance from the 1,000-fathom line at a point marking 

 the probable southern extension of Tasmania. Other 

 islands may have existed at intermediate points ; but, even 

 as it is, these distances are not greater than we know are 

 traversed by plants both by flotation and by aerial currents, 

 especially in such a stormy atmosphere as that of the 

 Antarctic regions. Now, we may further assume, that 

 what we know occurred within the Arctic circle also took 

 place in the Antarctic — that is, that there have been 

 alternations of climate during which some portion of what 

 are now ice-clad lands became able to support a con- 

 siderable amount of vegetation.^ During such periods 

 there would be a steady migration of plants from all 

 southern circumpolar countries to people the comparatively 

 unoccupied continent, and the southern extremity of 

 America being considerably the nearest, and also being the 

 best stocked with those northern types which have such 

 great powers of migration and colonisation, such plants 

 would form the bulk of the Antarctic vegetation, and 

 during the continuance of the milder southern climate 

 would occupy the whole area. 



When the cold returned and the land again became ice- 

 clad, these plants would be crowded towards the outer 

 margins of the Antarctic land and its islands, and some of 

 them would find their way across the sea to such countries 

 as offered on their mountain summits suitable cool 

 stations ; and as this process of alternately receiving plants 

 from Chile and Fuegia and transmitting them in all 

 directions from the central Antarctic land may have been 



^ The recent discovery by Lieutenant Jensen of a rich flora on rocky peaks 

 rising out of the continental ice of Greenland, as well as the abundant 

 vegetation of the highest northern latitudes, renders it possible that even 

 now the Antarctic continent may not be wholly destitute of vegetation, 

 although its climate and physical condition are far less favourable than 

 those of the Arctic lands. (See Nature^ Vol. XXI. p. 345.) 



