274 ESS A YS. 



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 Eu- 

 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. 36° 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. 



