388 THE NORTH POLAR BASIN. 



compelled to emigrate in search of food by some great catastrophe, such 

 as au abnormally heavy snow-fall, and the fact that uo island contains 

 more than one species is strong evidence that this great catastrophe 

 has only occurred once in recent times. The occurrence of a well rec- 

 ognized line of migration from Greenland across Iceland, the Faroes, 

 and the British Islands to Europe is strongly suggestive of a recent 

 elevation of the laud where the more shallow sea now extends in this 

 locality. The extraordinary similarity of the fauna and flora of the 

 Arctic regions of the Old and the New Worlds can only be fonnd else- 

 where in continuous areas, and had it not been for the unfortuuate 

 division of the Arctic region into two halves, PaUiearctic and jSTearctic, 

 would have attracted much more attention than it has hitherto 

 received. 



ARCTIC CLIMATE. 



The raiu-fall of the Polar Basin is small compared to that with which 

 we are familiar, but its visible effects are enormous. In Arctic Europe 

 and Siberia it is supj)osed to average about 13 inches per annum; in 

 Arctic America not more than 9 inches. The secret of its power is that 

 about a third of the rain-fall descends in the form of snow, which melts 

 with great suddenness. 



The stealthy approach of winter on the confines of the Polar Basin is 

 in strong contrast to the catastrophe which accompanies the sndden 

 onrush of summer. One by one the flowers fade, and go to seed if they 

 have been fortunate enough to attract by their brilliancy a bee or other 

 suitable pollen-bearing visitor. The birds gradually collect into flocks 

 and prepare to wing their way to southern climes. Strange to say, it is 

 the young birdsof each sj^ecies that set the example. They are not many 

 weeks old. They have no personal experience of migration, but nature 

 has endowed them with an inherited impulse to leave the land of their 

 birth before their parents. Probably they inherit the impulse to migrate 

 without inheriting any knowledge of where their winter quarters are to 

 be found, and by what route they are to be sought. They are sometimes, 

 if not always, accompanied by one or two adults; it may be barren 

 birds, or birds whose eggs or young have been destroyed, or who may 

 therefore get over their autumn molt earlier than usual, or molt slowly 

 as they travel southward. Of most species the adult males are the next 

 to leave, to be followed perhaps a week later by the adult females. One 

 by one the various migratory species disappear, until only the few resi- 

 dent birds are left, and the Arctic forest and tundra resume the silence 

 so conspicuous in winter. As the nights get longer the frosts bring 

 down the leaves from the birch and the larch trees. Summer gently 

 falls asleep, and winter as gently steals a march upon her, with no wind 

 and no snow, until the fi^ost silently lays its iron grip upon the river, 

 which, after a few impotent struggles, yields to its fate. The first, and 

 mayhap the second ice is broken up, and when the starrester of the 



