NATURAL HISTORY STUDIES 



brings in northern, latitudes there is great variety 

 of answer-back on the part of living creatures. Of 

 this variety let us take a few illustrations. Thus 

 most of our birds, emblems of freedom, escape the 

 spell by flight ; and, though death is often fleeter 

 still and overtakes them by the way, there can be 

 no doubt that the migration-solution is an effective 

 one. 



Other creatures, unequal to the long and adven- 

 turous journeys of the birds, retire into winter- 

 quarters, in which they lie low, awaiting happier 

 days. Thus the earth-worms burrow more deeply 

 than ever below the reach of the frost, the lemmings 

 tunnel their winding ways beneath the icy crust of 

 the Tundra, all manner of insects in their pupa-stages 

 lie inert within cocoons or other protective enve- 

 lopes in sheltered corners, the frogs get into holes 

 or bury themselves deeply in the mud by the side of 

 the pond, and the slow-worms coil up together in 

 their retreats all trying to get below the deadly 

 grip of the frost's fingers. 



Others, again, such as the Arctic fox, the moun- 

 tain hare, the ermine, the Hudson's Bay lemming, 

 and the ptarmigan, face the dread enchantment of 

 winter, but turn paler and paler under the spell, 

 until they are white as the snow itself a safety- 

 giving pallor. It is part of their constitution or 

 inborn make-up to change their colour, and the 

 external cold pulls the trigger that sets the process 

 at work. The use of the change of colour is, at 

 least, twofold the white dress is of service in the 

 chase or in flight, while, on the other hand, it is the 



196 



