SOME ALPINE CLIMBERS. 207 



members of larger continental groups which are excep- 

 tionally easy of transport by wind or weather. But our 

 Scotch and Welsh mountains still preserve in one place 

 or another an immense number of the old glacial plants, 

 without respect to the size of their seeds, the edibility of 

 their fruits, or the suitability of their actual embryos to 

 conveyance by birds or other known means of transport. 

 There is no way of explaining the frequency of their oc- 

 currence except by supposing (what we have otherwise 

 every reason to believe) that they once spread over the 

 whole of the surrounding regions, and have been slowly 

 ousted from the lower districts by better adapted tem- 

 perate lowland forms, so that they now survive only on 

 the higher rocky points which alone suit their northern 

 constitutions. Moreover, they are also for the most 

 part moribund races ; they do not belong to dominant 

 types which are now making their way triumphantly 

 over the world, but to types left behind in the struggle 

 for existence ; and so, though they may still feebly live 

 on against intruders in their own ancestral haunts, they 

 are hardly likely to fight out the battle against other 

 species if casually dropped into the midst of already oc- 

 cupied and settled districts. 



A great many of these stranded glacial flowers still 

 spread widely over the larger part of the Highlands or 

 of the Welsh hills, as in the case of the little creeping 

 mountain sibbaldia, which forms the main element in the 

 greensward of the Perthshire moors, or again as with the 

 Alpine hawkweed and the common crowberry, which 

 grow abundantly as far southward as the Merioneth 

 cairns. But a more interesting class of glacial stragglers 

 are those which now loiter only on one or two solitary 

 mountain-tops in Britain, and do not again appear until 

 we reach the higher Swiss pastures or the frost-bound 



