14] 
zones of vegetation, in parallelism with zones.of temperature, till, pro- 
gressing towards the pole, trees became utterly stunted, every trace of 
verdure disappeared, and a few,soli‘ary lichens, amongst pyramids of 
ice, or a stain of crimson amidst wastes of snow, alone testified to the 
all but extinguished spark of phytological existence. These zones of 
vegetation were repeated upon the mountains, with their increasing 
height, in exact correspondence between the decrement of heat from 
the equator to the poles. On the Alps and Pyrenees, at the elevation 
of 8,780 feet, it was as cold as the region of the poles at the level of 
the sea, and though the snow-line was higher at the equator, even 
there all vegetation ceased at an elevation of 15,200 feet. The size 
of plants was much diminished on the sides of mountains ; but the 
beauty of natural Alpine gardens, among black ravines and broken 
crags, was so exciting, that any one who once trod upon such 
an oasis of beauty long remembered it amid the dusty scenes of every- 
day life. Though the distribution of plants on the earth was clearly 
governed by temperature, the “isothermal lines” of mean annual 
heat did not progress uniformly, and thus the eastern countries 
of Europe, Asia, and America had a much lower temperature than the 
western, and plants were affected accordingly. In Norway, the silver 
fir, black alder, and others, grew under the polar circle, while eastern 
Siberia and the vast extent of Labrador, north of 60 deg., was quite 
treeless. The limitation of the cultivated plants was next noticed :— 
nutmegs, coffee, cocoa, and the finest spices, were limited to inter- 
tropical regions; cotton, rice, and olives grew in lat. 45 deg.; the 
vine, to 50 deg. ; while in the West of Europe; the cultivation of wheat, 
flax, and tobacco, ceased at 60 deg.; but hemp, oats, barley, rye, and 
potatoes, progressed into the polar circle. The southern hemisphere, 
from the greater accumulation of ice at the poles, was colder than the 
northern. This was well shown by a comparison of the indigenous 
flowering plants of our little Channel Islands, Guernsey, Jersey, &c., 
_with the larger Kerguelen’s group, in the same parallel of latitude 
South. The former isles possessed 840 species, but Kerguelen’s only 
82. The physiognomy of vegetation was next adverted to, those 
peculiar features of associated plants that the eye at once seized upon, 
in any country, and connected with early recollection, as “ the vege- 
table forms of our father-land.” Seas, mountain-chains by their inter- 
vention, formed provinces of plants, and thus the greatest diversity 
_prevailed in the clothing of the earth’s surface. As striking examples, 
the forests of Australia and Van Diemen’s Land were composed of ever- 
green Euealypti; tree-ferns abounded in New Zealand ; the singular 
