Castings of a similar
nature continued to be ejected from the burrow during the whole of
the following day.
As doubts have been expressed by some writers whether worms ever
swallow earth solely for the sake of making their burrows, some
additional cases may be given. A mass of fine reddish sand, 23
inches in thickness, left on the ground for nearly two years, had
been penetrated in many places by worms; and their castings
consisted partly of the reddish sand and partly of black earth
brought up from beneath the mass. This sand had been dug up from a
considerable depth, and was of so poor a nature that weeds could
not grow on it. It is therefore highly improbable that it should
have been swallowed by the worms as food. Again in a field near my
house the castings frequently consist of almost pure chalk, which
lies at only a little depth beneath the surface; and here again it
is very improbable that the chalk should have been swallowed for
the sake of the very little organic matter which could have
percolated into it from the poor overlying pasture. Lastly, a
casting thrown up through the concrete and decayed mortar between
the tiles, with which the now ruined aisle of Beaulieu Abbey had
formerly been paved, was washed, so that the coarser matter alone
was left.
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