254 ARCTIC AND TROPICAL VEGETATION. 



In tropical regions as we have already ventured to 

 point out, the exuberance of life, and of vegetative 

 power, seems to overflow the landmarks set up by 

 human skill and labour, much as the rising tide sweeps 

 in upon and covers the beach, left dry below high 

 water mark *: here, in the Arctic Zone however, we 

 have reached a region where these operations of Nature 

 are distinguished by a quiescence closely resembling 

 that of an eternal sleep; so slowly do they work. 

 Thus specimens of the arctic birch, found by Norden- 

 skiold the Swedish explorer, in Spitzbergen, " did not 

 exceed two feet " in height, " the thickest stem being 

 2 to 3 lines in diameter" (that is, equal to about one 

 quarter of an inch in thickness). Yet after the return 

 of the expedition to Sweden, when examined by the 

 help of a microscope, " a stem this thickness was found 

 to be about 60 years old." f Contrast this vegetative 

 torpor with the shooting up of giant bamboos to a 

 height of 120 feet, in 3 or 4 months, during the tropi- 

 cal rains. Yet when we come to consider the matter, 

 this exceeding slowness of growth in arctic climates 

 ought not to appear to be so very remarkable, seeing 

 that frost prevails there throughout almost the entire 

 year, during which vegetation is for the most part at 

 a standstill. 



But the marvellous vegetative power of the tropical 

 sun is thereby exhibited in its most striking 

 aspect. Some experiments have from time to time 

 been made, with a view to ascertain how far the thaw 

 penetrated into the soil during the brief duration of 

 an arctic summer, which tend to show that 



* See our chapter on "The Equatorial Zone." 



j Professor A. E. Nordenskiold's Arctic Voyage, 1881, p. 186. 



