CASES OF ADAPTATiOxX 151 



graphical Distribution of the Plovers and allied birds, he gives 

 a most graphic account of this country and of the birds flock- 

 ing to it, which is worth quoting, as few people have any ade- 

 quate idea of what the greater part of the iirctic regions really 

 are in summer. After describing its extent and boundaries, 

 he says: 



" I have called this district a paradise, and so it is for two 

 or three months of the year. Nowhere else in the whole world can 

 you find such an abundance of animal and vegetable life, brilliant 

 flowers, birds both of gay plumage and melodious of song, where 

 perpetual day smiles on sea and river and lake. For eight months 

 or more (according to the latitude) every trace of vegetable life is 

 completely hidden under a thick blanket which absolutely covers 

 every plant and bush. Far as the eye can reach, in every direction 

 nothing is to be seen but an interminable, undulating plain of white 

 snow." 



Then after describing the few animals that live there even 

 during the wunter, and the strange phenomenon in May of 

 continuous day and almost perpetual sunshine, at midday hot 

 enough to blister the skin, yet still apparently in mid-winter 

 so far as the snow is concerned, he goes on to describe what 

 there takes place: 



" The disc of snow surrounding the North Pole at the end of 

 May extends for about two thousand miles in every direction where 

 land exists, and is melting away on its circumference at the rate 

 of about four miles an hour, and as it takes a week or more to melt, 

 it is in process of being melted for a belt of several hundred miles 

 wide round the circumference. This belt is crowded with migratoiv 

 birds eager to push forwards to their breeding grounds — hurrying 

 on over the melting snow so long as the south wind makes bare 

 places soft enough to feed on, but perpetually being driven back 

 by the north wind, which locks up their food in its ice-chest. 

 . . . In watching the sudden arrival of summer on the Arctic 

 circle, both in the valley of the Petchora, in East Eussia, and in 

 the valley of the Yenesay, in Central Siberia, I was impressed with 

 the fact that the influence of the sun was nearly nothing, while 



