274 ESSAYS. 
nent on the eastern side unbroken and open from the arctic 
circle to the tropic, and the mountains running north and 
south. The vegetation when pressed on the north by on- 
coming refrigeration had only to move its southern border 
southward to enjoy its normal climate over a favorable region 
of great extent; and, upon the recession of glaciation to the 
present limit, or in the oscillations which intervened, there 
was no physical impediment to the adjustment. Then, too, 
the more southern latitude of this country gave great advan- 
tage over Europe. The line of terminal moraines, which 
marks the limit of glaciation, rarely passes the parallel of 40° 
or 39°. Nor have any violent changes occurred here, as they 
have on the Pacific side of the continent, within the period 
under question. So, while Europe was suffering hardship, 
the lines of our Atlantic American flora were cast in pleasant 
places, and the goodly heritage remains essentially unim- 
paired. 
The transverse direction and the massiveness of the moun- 
tains of Europe, while they have in part determined the com-' 
parative poverty of its forest-vegetation, have preserved there 
a rich and widely distributed alpine flora. That of Atlantic 
North America is insignificant. It consists of a few arctic 
plants, left scattered upon narrow and scattered mountain- 
tops, or in cool ravines of moderate elevation ; the maximum 
altitude is only about 6000 feet in lat. 44°, on the White 
Mountains of New Hampshire, where no winter snow outlasts 
mid-summer. The best alpine stations are within easy reach 
of Montreal. But as almost every species is common to Ku- 
rope, and the mountains are not magnificent, they offer no 
great attraction to a European botanist. 
Farther south, the Appalachian Mountains are higher, be- 
tween lat. 836° and 34° rising considerably above 6000 feet ; 
they have botanical attractions of their own, but they have no 
alpine plants. A few sub-alpine species linger on the cool 
shores of Lake Superior, at a comparatively low level. Per- 
haps as many are found nearly at the level of the sea on An- 
ticosti, in the Gulf of St. Lawrence, abnormally cooled by the 
Labrador current. 
