CHAPTER III 



ADAPTATIONS TO HIGH ALTITUDES 



Ptarmigan The Marmot's sleep Canadian Ruffed Grouse 

 Spring Tails of the snow level The Alpine Salamander Some 

 characteristics of mountain plants Origins of British animals. 



IN the course of time living 1 creatures whether plants 

 or animals tend to become specially suited to the par- 

 ticular conditions of their life. The Whale is suited to 

 the open sea in its shape, its smoothness, its blubber, 

 its balancing flippers, its propelling flukes, and in a 

 score of other ways. The Cactus is suited to the arid 

 desert in its leaflessness, its thick skin, and its capacity 

 for storing water. Changes crop up, and, if the con- 

 ditions of life are not easy, there is discriminate sift- 

 ing; thus those varieties of each kind tend to survive 

 which are relatively fittest to particular habitats and 

 ways of living. This is the theory of Nature's sifting 

 or Natural Selection a sound theory so far as it goes, 

 but with the obvious drawback that it does not account 

 for, or pretend to account for, the inborn changeful- 

 ness which supplies the raw materials to be sifted. But 

 while the theory is still far from complete, there is no 

 doubt about the facts. Living creatures are bundles of 

 adaptations. As a great naturalist once said : 

 " Wherever you tap Organic Nature it seems to flow 

 with purpose." And our particular question now con- 

 cerns the ways in which plants and animals are suited 



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