tips of the tails of two of them, in 40 minutes. In none of these cases,
did the worms swallow, as far as could be seen, any earth. They
generally entered the ground close to the sides of the pot.
A pot was next filled with very fine ferruginous sand, which was pressed
down, well watered, and thus rendered extremely compact. A large worm
left on the surface did not succeed in penetrating it for some hours, and
did not bury itself completely until 25 hrs. 40 min. had elapsed. This
was effected by the sand being swallowed, as was evident by the large
quantity ejected from the vent, long before the whole body had
disappeared. 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. This consisted of grains of quartz, micaceous
slate, other rocks, and bricks or tiles, many of them from 1/20 to 1/10
inch in diameter. No one will suppose that these grains were swallowed
as food, yet they formed more than half of the casting, for they weighed
19 grains, the whole casting having weighed 33 grains. Whenever a worm
burrows to a depth of some feet in undisturbed compact ground, it must
form its passage by swallowing the earth; for it is incredible that the
ground could yield on all sides to the pressure of the pharynx when
pushed forwards within the worm s body.
That worms swallow a larger quantity of earth for the sake of extracting
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