22 ME. J. BALL ON THE TLORA 



We know that at a recent geological period, and very probably 

 at many preceding periods, the climate of the northern polar 

 regions was so far different as to favour the growth of plants now 

 characteristic of the warm temperate zone. Whatever may have 

 been the causes of such a change in the distribution of tempera- 

 ture, it is contrary to all analogy to assume that in the long record 

 of the vicissitudes in the condition of our planet similar causes 

 have not produced effects in some degree similar in the southern 

 hemisphere. Further than this, our limited knowledge of the 

 geology of the southern hemisphere suffices to show that most, 

 if not all, portions have undergonevery great oscillations of level, 

 involving as a necessary consequence alternate extension of the 

 areas of land and ocean. 



The diflSculties of antarctic navigation have, unfortunately, 

 hitherto limited our knowledge of the south polar regions ; and, 

 while many believe that a considerable continental area, wholly 

 or in part covered with perennial snow or ice, now surrounds the 

 southern pole, other geographers, with whom I am disposed to 

 agree, think it more probable that the south polar lands consti- 

 tute a great archipelago formed by numerous islands, some of 

 which are probably of great extent. Whatever may be the fact 

 at the present time, there is a strong probability that, in the 

 course of past changes of temperature and level, a mild climate 

 and an extensive area of Antarctic land may once, or very possibly 

 many times, have occurred simultaneously. 



Here, at a period remote even in geological language, we should 



look for the original home of those types of vegetation which we 

 designate as Antarctic. In opening a new region for habitation 

 to a comparatively few vegetable ancestors, the favourable con- 

 ditions for the development of new generic types were provided, 

 and the process would have been hastened by the frequent vicis- 

 situdes of temperature and moisture to which the climate of such 

 a region must have been subjected. 



I was altogether unconscious that in following this train of 

 speculation I was merely developing a suggestion contained in 

 the 12th chapter of the * Origin of Species ' *, which had failed 



* The passage, -which has only very recently been recalled to my recollection, 

 runs thus: — " This difficulty almost disappears on the view that New Zealand, 

 South America, and other southern lands were long ago partially stocked from 

 a nearly intermediate, though distant point, namely, from the Antarctic islands, 

 when they were clothed with vegetation, before the commencement of the Glacial 

 period." 



