490 



ISLAND LIFE. 



[part il 



a group of large islands probably extends across or around the 

 south polar area to Victoria Land and thence to Ad^lie 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 Mac- 

 quarie Islands are about the same distance from the 1,000- 

 fathom line, marking the probable southern extension of Tas- 

 mania. 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 assum.e, that what we know 

 occurred within the Arctic circle also took place in the Ant- 

 arctic — 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 coDsiderable amount of vegetation.-^ 

 During such periods there would be a steady migration of plants 

 from all southern circumpolar countries to people the com- 

 paratively unoccupied continent, and the southern extremity 

 of America being considerably the nearest, and also being the 

 best stocked with those northern types w^hich 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 th-e 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 trans- 

 mitting them in all directions from the central Antarctic land 

 may have been repeated several times during the Tertiary 

 jjeriod, we have no difficulty in understanding the general com- 



1 The recent discovery 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. 



