10 OUR WOODLAND TREES. 
and, in short, penetrating everywhere, endowed 
with mysterious persistence and vitality, and 
sometimes, with a grasp on life which withstands 
degrees of heat and cold that are fatal to the 
majority of plants, and of plant germs. 
If we turn from these, the most minute of the 
inhabitants of the great plant world, to the forms 
which, still minute, nevertheless come, individually, 
within the range of human vision, we shall but have 
reached another stage in the gradation of objects 
which le within the realm of the vegetable 
kingdom. Looking around from this new stand- 
point we shall find ourselves in quite another 
world, with almost exhaustless material for 
wondering admiration—the world of moss and 
lichen, where Nature, with ten thousand forms of 
beauty, carpets the ground, flings her green 
mantle over wall, and rock, and Tree trunk, and 
clothes sea-shore and stream-bank with a ver- 
dant host of her tiny children. 
One more stage upwards in the gradation of 
plant life. The forms which now engross our 
attention are small still; but they are of size 
sufficient to give us an indication of their pre- 
