which the particles of earth had been cemented together. They did not
disintegrate, even when left for some hours in water. Although they had
been cast up on the surface of gravelly soil, they contained extremely
few bits of rock, the largest of which was only 0.15 inch in diameter.
Dr. King saw in Ceylon a worm about 2 feet in length and 1 2 inch in
diameter; and he was told that it was a very common species during the
wet season. These worms must throw up castings at least as large as
those on the Nilgiri Mountains; but Dr. King saw none during his short
visit to Ceylon.
Sufficient facts have now been given, showing that worms do much work in
bringing up fine earth to the surface in most or all parts of the world,
and under the most different climates.
CHAPTER III.
THE AMOUNT OF FINE EARTH BROUGHT UP BY WORMS TO THE SURFACE.
Rate at which various objects strewed on the surface of grass-fields are
covered up by the castings of worms The burial of a paved path The slow
subsidence of great stones left on the surface The number of worms which
live within a given space The weight of earth ejected from a burrow, and
from all the burrows within a given space The thickness of the layer of
mould which the castings on a given space would form within a given time
if uniformly spread out The slow rate at which mould can increase to a
great thickness Conclusion.
WE now come to the more immediate subject of this volume, namely, the
amount of earth which is brought up by worms from beneath the surface,
and is afterwards spread out more or less completely by the rain and
wind. The amount can be judged of by two methods, by the rate at which
objects left on the surface are buried, and more accurately by weighing
the quantity brought up within a given time. We will begin with the
first method, as it was first followed.
Near Mael Hall in Staffordshire, quick-lime had been spread about the
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