ALPINE AND ARCTIC PLANTS 447 



they have passed, one is tempted to believe that it is the 

 tendency of the "struggle for existence" to confirm and ren- 

 der permanent the characters of species rather than to modify 

 them. 



Of the more specially Arctic plants which have held their 

 ground unchanged on Mount Washington, the following are 

 some of the principal. Diapensia Lapponica, in beautiful deep 

 green tufts, ascends quite to the summit. It occurs also in the 

 Adirondack Mountains, on Mount Katahdin, in Maine, and on 

 the summit of Mount Albert, Gasp (Macoun). It is found 

 in Labrador, and, according to Hooker, extends north to 

 Whale Island, in the Arctic seas ; but it is not found west of 

 the Great Fish River. It occurs also on the mountains of 

 Lapland, and is described as the hardiest plant of that bleak 

 region. Arenaria (A/sine) Groenlandica, the Greenland sand- 

 wort, adorns with its clusters of white flowers every sandy 

 crevice in the rocks of the very summit of Mount Washington, 

 and is trodden under foot like grass by the hundreds of care- 

 less sightseers that haunt that peak in summer ; though I 

 should add, that not a few of them carry off little tufts as a 

 memento of the mountains, along with the fragments of mica 

 which appear to form the ordinary keepsakes of unscientific 

 visitors. It is a most frail and delicate plant, seemingly alto- 

 gether unsuited to the dangerous pre-eminence which it seeks, 

 yet it loves the bare, unsheltered mountain peaks, and when it 

 occurs in the more sheltered ravines, has only its stems a little 

 longer and more slender. It occurs on the Adirondack 

 Mountains and on Katahdin, where, if I may judge from 

 specimens kindly sent to me by Prof. Goodale, it attains to 

 smaller dimensions than on Mount Washington, on the Cats- 

 kills, and at one place on the sea coast of Maine. I have not 

 seen it in Nova Scotia, but it ranges north to Greenland. 



Another of the truly Arctic plants is the alpine azalea (Loi- 

 seleuria procumbent), a densely tufted mountain shrub, with 



