XXXYI. 



SOME ALPINE CLIMBERS. 



ON the very summit of the moor here, among the 

 mossy clefts of the weathered granite, a few straggling 

 tufts of northern rock-cress still manage to keep good 

 their footing on an area not wider in every direction 

 than the circle described by a radius of some four or five 

 hundred yards from the central boulder on which I am 

 sitting. Small as is the patch of ground over which 

 they thus extend, they can doubtless boast a very con- 

 siderable prehistoric antiquity ; for there is every reason 

 to believe that they and their ancestors have struggled 

 on here in lonely isolation ever since the end of the 

 great glacial era. Nothing adds so much to the romance 

 of natural history as the fixed habit of regarding every 

 separate colony of plants or animals as a tribe or com- 

 munity, necessarily restricted to intermarriage with 

 other members of the same group in the same place ; it 

 almost compels one to ask one's self in each case, how did 

 they first get here, and how did they come to be per- 

 manently severed from the main body of their species 

 elsewhere ? Now northern rock-cress is by origin a sub- 

 arctic plant, spreading along all the higher ranges of 

 Scandinavia, Russia, and Siberia, with a few isolated 

 outliers among the snowy mountains of southern Europe. 

 Here in Britain it occurs on the main summits of the 

 Scotch Highlands, descends more scantily into Wales or 

 Cumberland, and hardly loiters on upon a few bleak hill- 

 tops in Ireland among the Ulster heights. This moor 



