158 LIFE AND HER CHILDREN. 
same plan as the land-insects, which have spread so 
far and wide over the globe. These are an active busy 
multitude, which, if they could think and speak, would 
have far more right to call this earth their world than 
we have to call it ours ; for whether in the sea, or in 
the rivers and ponds ; in the fields, forests, or marshes ; 
at the tops of mountains, or in underground caves 
and passages ; in our gardens, our cellars, our houses, 
or about our persons ; anywhere, everywhere, all over 
the world their hosts are to be found. 
We are accustomed to attach great importance to 
the back-boned animals, the fishes, reptiles, birds, lions, 
elephants, and monkeys, because they are compara- 
tively large and conspicuous, but in truth, if we ex- 
cept the human race, they are as nothing, either in 
number or in activity and ingenuity, as compared with 
the insects and their allies. 
If we could take one of each species of all the 
back-boned animals, and add to them all the species 
of worms, mollusca, prickly-skinned animals, lasso- 
throwers, sponges, and lime and flint builders, 'all 
these together would only make up 50,000 species, 
or one-fifth of the animals on the globe ; the other 
four-fifths, or 200,000 species, belong to the ringed and 
jointed-footed animals, and of these I 5 0,000 are the 
six-legged insects. Now we have learnt that if crea- 
tures succeed in the battle of life, it is because they 
can hold their own and fight bravely, and therefore 
we are prepared to find that life has taught these, her 
active children, many new lessons and armed them 
with many useful tools and weapons, differing greatly 
according to the lives they have to lead. 
And first of all we must turn our attention to the 
