124 FIRST FORMS OF VEGETATION. 
eyes of the illustrious Humboldt, when stand- 
ing within a few hundred feet of the summit of 
Chimborazo, the highest peak of the Andes. 
Strange it must have seemed to this enterprising 
traveller to stand on that elevated spot, and to 
see around and beneath him an epitome, as it 
were, of what takes place on a grander scale over 
the whole globe—a condensed picture of all the 
climates of the earth from the tropics to the poles, 
with all their different zones or belts of vegetation. 
Above towered the inaccessible summit in its 
everlasting shroud of stainless snow, boldly re- 
lieved against the deep cloudless blue of the 
tropical sky ; around him the bare and rugged 
trachytic rocks, enamelled with the primrose- 
coloured crust of this beautiful lichen, a few pale 
tufts of moss, or a solitary flower drooping here 
and there its frail head from a crevice ; immedi- 
ately beneath him the green grass-clad slopes, 
variegated with rainbow-coloured flowers and 
stunted willow-like shrubs; and far down in the 
valleys at the base, a glowing gorgeous world of 
tropical luxuriance—palms and bananas and bam- 
boos, dimly revealed through the seething, swel- 
tering vapours which perpetually surrounded 
them. 
The Lecidea geographica aftords, I may mention, 
the most remarkable example of the almost 
