THE MYSTERIOUS BALANCE- 
153 
it was by dancing they at last found where to pitch their 
tents, and cease their nomad wanderings. But they all 
work together to sustain the balance, and the law of 
“give and take” prevails amongst them—the stentor 
devours the oscillatorim, rotatoria., and monads, and the 
hydras swallow all; every darting speck is a tomb where¬ 
in some smaller speck of life is to be buried, and life thus 
prospers on the decay it is itself undergoing. 
But all this while a fine deposit slowly settles among 
the pebbles, which form the lower stratum of this watery 
world. Between the stones a fine alluvial silt collects 
and thickens. The first frost, sufficiently severe to touch 
the tank, causes the whole green coating to peel off 
from the glass and rock, and while this subsides, to add 
to the thickness of the alluvium—how slightly, and 
yet how sufficiently for an example of Nature^s working ! 
—a new growth commences, and that balance is restored* 
Do you not see that the chief teaching of geology—the 
piling of stratum upon stratum, the conversion of dis¬ 
rupted rock and decayed plant and animal into rock 
again—is here exemplified in the history of a domestic 
toy, which contains already one example of stratification 
in the silence of watery submergence ? A tank which 
has been fitted with loam, pebbles, and plants of the 
brook and river, will, if left undisturbed for three years, 
be in this state. Those plants will all have decayed, but 
there will be an abundant spontaneous vegetation. The 
accumulations of that short period will have settled into 
a close mass, almost as hard as stone; and if fishes have 
died in the meantime, and have not been removed, their 
bones will be found overlaid with hardened mud, just 
