2 LIFE AND HER CHILDREN. 
our mantelpiece is the work of once living animals, 
and is composed of their broken shells. The air we 
breathe is full of invisible germs of life ; nor need 
we leave the town and go to the country in search 
of other living beings than man. There is scarcely 
a street or alley where, if it be neglected for a 
time, some blade of grass or struggling weed does 
not make its appearance, pushing its way through 
chinks in the pavement or the mortar in the wall ; 
no spot from which we cannot see some insect creep- 
ing, or flying, or spinning its web, so long as the 
hand of man does not destroy it. 
And when we go into the quiet country, leaving 
man and his works behind, how actively we find life 
employed ! Covering every inch of the ground with 
tiny plants, rearing tall trees in the forest, filling the 
stagnant pools full of eager restless beings ; anywhere, 
everywhere, life is at work. Look at the little water- 
beetles skimming on the surface of the shady wayside 
pool, watch the snails feeding on the muddy bank, 
notice the newts putting their heads above water 
to take breath, and then remember that, besides these 
and innumerable other animals visible to the naked eye, 
the fairy-shrimp and the water-flea, and other minute 
creatures, are probably darting across the pond, or 
floating lazily near its surface ; while the very scum 
which is blown in ridges towards one corner of the 
pool is made up of microscopic animals and plants. 
Then, as we pass over plain, and valley, and 
mountain, we find things creeping innumerable, both 
small and great; some hidden in the moss or the thick 
grass, rolled up in the leaves, boring into the stems 
and trunks of trees, eating their way underground or 
