4 FIRST FORMS OF VEGETATION. 
lowest. Every inch of ground, however ungenial 
its climate or unfavourable its conditions, is made 
available ; every object, however unlikely at first 
sight, is pressed into her service, and made to bear 
its burden of life. From the deepest recesses of the 
earth to which the air can penetrate, to the sum- 
mits of the loftiest mountains; from the almost 
unfathomable depths of the ocean to the highest 
clouds; from pole to pole, the vast stratum of 
vegetable life extends; while it ranges from a 
temperature of 35° to 135° Fah.,a range embracing 
almost every variety of conditions and circum- 
stances; and thus the grandly wild Platonic 
myth of the cosmos, as one vast living thing, is 
not altogether without foundation. 
The most cursory and superficial glance will 
recognise in every scene a class of plants whose 
singular appearances, habits, and modes of growth 
are so widely different from those of the trees and 
flowers around, that they might seem hardly 
entitled to a place in the vegetable kingdom at 
all. On walls by the wayside, on rocks on the 
hills, and on trees in the woods, we see tiny green 
tufts and grey stains, or particoloured rosettes 
spreading themselves, easily dried by the heat of 
the sun, and easily revived by the rain. In almost: 
every stream, lake, ditch, or any collection of 
standing or moving water, we observe a green 
