170 THE GEOGRAPHY OF PLANTS. 



from the equator towards the south pole than 

 towards the north. Vegetation decreases as 

 the latitude increases, till at length utter deso- 

 lation reigns. This is partly owing to the 

 want of heat in summer and more than to the 

 greater cold in winter. In high northern lati- 

 tudes, the power of the summer sun is so great 

 as to melt the pitch between the planks of the 

 vessels ; while, in corresponding southern lati- 

 tudes, the thermometer does not rise above 14 

 (18 below the freezing point) at noon, in a 

 season corresponding to our August. Sand- 

 wich Land, in a latitude corresponding to the 

 north of Scotland, is perpetually covered with 

 many fathoms of snow. The south Shetland 

 Isles have but one flowering plant, a grass, 

 (Aim antarctica^) and are no less ice-bound 

 than the last ; while the Shetland Isles, in the 

 north of Scotland, in an equally high latitude, 

 are both inhabited and cultivated. South 

 Georgia, in the same latitude as Yorkshire, but 

 south, is always clad in frozen snow, and pro- 

 duces only a few lichens, mosses, and wild 

 burnet ; while Iceland, ten degrees nearer the 

 pole in the northern hemisphere, has eight 

 hundred and seventy species, more than half ot 

 which are flowering plants. But a few degrees 

 makes a great difference in the southern hemi- 

 sphere. Terra del Fuego, only six degroes 

 nearer the equator than the frozen south Shet- 

 land, is clad with dense forests of winter's baric 

 and beech. Species of arbutus, myrtle, bar- 

 berry, currant, and fuchsia ; and calceolarias. 



