earth was examined under a high power, and the number of spores of
various shapes and sizes which it contained was astonishingly great; and
these crushed in the gizzards of worms may largely aid in supporting
them. Whenever castings are thrown up in the greatest number, few or no
leaves are drawn into the burrows; for instance the turf along a
hedgerow, about 200 yards in length, was daily observed in the autumn
during several weeks, and every morning many fresh castings were seen;
but not a single leaf was drawn into these burrows. These castings from
their blackness and from the nature of the subsoil could not have been
brought up from a greater depth than 6 or 8 inches. On what could these
worms have subsisted during this whole time, if not on matter contained
in the black earth? On the other hand, whenever a large number of leaves
are drawn into the burrows, the worms seem to subsist chiefly on them,
for few earth-castings are then ejected on the surface. This difference
in the behaviour of worms at different times, perhaps explains a
statement by Claparede, namely, that triturated leaves and earth are
always found in distinct parts of their intestines.
Worms sometimes abound in places where they can rarely or never obtain
dead or living leaves; for instance, beneath the pavement in well-swept
courtyards, into which leaves are only occasionally blown. My son Horace
examined a house, one corner of which had subsided; and he found here in
the cellar, which was extremely damp, many small worm-castings thrown up
between the stones with which the cellar was paved; and in this case it
is improbable that the worms could ever have obtained leaves. Mr. A. C.
Horner confirms this account, as he has seen castings in the cellars of
his house, which is an old one at Tonbridge.
But the best evidence, known to me, of worms subsisting for at least
considerable periods of time solely on the organic matter contained in
earth, is afforded by some facts communicated to me by Dr. King. Near
Nice large castings abound in extraordinary numbers, so that 5 or 6 were
often found within the space of a square foot. They consist of fine,
pale-coloured earth, containing calcareous matter, which after having
passed through the bodies of worms and being dried, coheres with
considerable force. I have reason to believe that these castings had
been formed by species of Perich ta, which have been naturalized here
from the East. {101} They rise like towers, with their summits often a
little broader than their bases, sometimes to a height of above 3 and
often to a height of 21 2 inches. The tallest of those which were measured
49