SNOW CAVERNS. 313 



were not migratory, but had held their position through the 

 whole icy period. While the finding of living willow trunks, 

 grass, and perennial plants of many years growth, close to 

 the edges of retreating glaciers, seems to place the point 

 beyond any reasonable doubt." * 



The length of time during which these growths may 

 have remained in a state of suspended vitality, beneath 

 the ice, is of course a matter which there are no means 

 of determining. All that can be said on that head is, 

 that so far as is known, glaciers retain their positions 

 for long periods of time, without any considerable 

 change. They are, known to be always moving, but so 

 slowly that their advance sometimes amounts to only 

 a few feet in the course of a year. 



Returning however to the questions respecting 

 animal life in the polar regions, we find that all 

 these small arctic animals, to which we have referred, 

 are of the order " Rodentia " (except the marten, 

 \Mustela Erinined\ a creature which doubtless lives by 

 preying upon the others) ; all of these therefore, 

 presumably feed upon the leaves, bark and shoots of 

 shrubs and plants, and all of them, the hare included, 

 live in the snow drifts (where the arctic hare has 

 holes like a rabbit), and there can be no doubt that 

 they burrow down, and descend to the surface of 

 the earth in order to reach these plants, which are, as 

 we venture to believe, continually growing there. 



It might perhaps be supposed that the act of always 

 mining through heavy masses of snow would prove 

 a work of endless labour, difficulty, and danger, to 

 any creature that might attempt it. Observations upon 



* See Article on The Flora of Greenland, in The Athenceum for 

 June 24, 1893, p. 187. 



