the surface. It is very improbable that worms should have migrated from
the adjoining field into the small space of the atrium, after the
superficial mould in which they prefer to live, had been removed. We may
therefore conclude that the burrows and the castings which were seen here
during the ensuing seven weeks were the work of the former inhabitants of
the space. I will now give a few extracts from Mr. Farrer s notes.
Aug. 26th, 1877; that is, five days after the floor had been cleared. On
the previous night there had been some heavy rain, which washed the
surface clean, and now the mouths of forty burrows were counted. Parts
of the concrete were seen to be solid, and had never been penetrated by
worms, and here the rain-water lodged.
Sept. 5th. Tracks of worms, made during the previous night, could be seen
on the surface of the floor, and five or six vermiform castings had been
thrown up. These were defaced.
Sept. 12th. During the last six days, the worms have not been active,
though many castings have been ejected in the neighbouring fields; but on
this day the earth was a little raised over the mouths of the burrows, or
castings were ejected, at ten fresh points. These were defaced. It
should be understood that when a fresh burrow is spoken of, this
generally means only that an old burrow has been re-opened. Mr. Farrer
was repeatedly struck with the pertinacity with which the worms re-opened
their old burrows, even when no earth was ejected from them. I have
often observed the same fact, and generally the mouths of the burrows are
protected by an accumulation of pebbles, sticks or leaves. Mr. Farrer
likewise observed that the worms living beneath the floor of the atrium
often collected coarse grains of sand, and such little stones as they
could find, round the mouths of their burrows.
Sept. 13th; soft wet weather. The mouths of the burrows were re-opened,
or castings were ejected, at 31 points; these were all defaced.
Sept. 14th; 34 fresh holes or castings; all defaced.
Sept. 15th; 44 fresh holes, only 5 castings; all defaced.
Sept. 18th; 43 fresh holes, 8 castings; all defaced.
82