280 GEOGEAPHICAL DISTRIBUTION OF PLANTS. 



an instant. This humidity gives astonishing vigour to the 

 vegetation, yet corn does not grow there ; and, in fact, the 

 want of level surface is an impediment to cultivation. In 

 six weeks the botanists collected 222 species of plants, of 

 which thirty-five were new to science. 



Of the Polar plants, amounting to ninety-one species, 

 which inhabit Melville Island, the shores of Barrow's 

 Straits and Lancaster Sound, and the north coasts of Green- 

 land, between the 73rd and 75th parallels of latitude, 

 about seven-ninths range to Greenland, Lapland or 

 Northern Asia. Of the remainder, some have been 

 gathered on the shores of the Arctic Sea from Baffin's 

 Bay to Beering's Straits; and it is probable that if 

 these high latitudes were fully explored, the flora of the 

 entire zone would be found to be uniform. Some of the 

 more local plants will perhaps be ascertained, on further 

 acquaintance, to be mere varieties altered by peculiarities 

 of climate. That the flora as well as the fauna in the high 

 northern latitudes is nearly alike in the several meridians 

 of Europe, Asia, and America, has long been known. And 

 even when we descend to some distance south of the arctic 

 circle, we find that this law is superior to the intrusion of 

 high mountain chains, and is but partially infringed upon. 

 In taking the St. Lawrence basin for instance, if we allow 

 for the rise of the isothermal lines on the west coast, and 

 make our comparisons in an oblique zone, including Sitka 

 and Wisconsin, we shall find that there is much similarity 

 in the floras on the two sides of the continent. The Rocky 

 Mountain ridge is not by any means a boundary to the 

 peculiar vegetable forms of the Pacific coast ; on the con- 

 trary, many of them cross the ridge to its eastern declivity, 

 though they do not descend into the low country; and 

 there is actually more similarity between the vegetation of 



