out of the ground by the innumerable roots of the trees; for such places
may be seen covered with castings after the heavy autumnal rains.
Although most coppices and woods support many worms, yet in a forest of
tall and ancient beech-trees in Knole Park, where the ground beneath was
bare of all vegetation, not a single casting could be found over wide
spaces, even during the autumn. Nevertheless, castings were abundant on
some grass-covered glades and indentations which penetrated this forest.
On the mountains of North Wales and on the Alps, worms, as I have been
informed, are in most places rare; and this may perhaps be due to the
close proximity of the subjacent rocks, into which worms cannot burrow
during the winter so as to escape being frozen. Dr. McIntosh, however,
found worm-castings at a height of 1500 feet on Schiehallion in Scotland.
They are numerous on some hills near Turin at from 2000 to 3000 feet
above the sea, and at a great altitude on the Nilgiri Mountains in South
India and on the Himalaya.
Earth-worms must be considered as terrestrial animals, though they are
still in one sense semi-aquatic, like the other members of the great
class of annelids to which they belong. M. Perrier found that their
exposure to the dry air of a room for only a single night was fatal to
them. On the other hand he kept several large worms alive for nearly
four months, completely submerged in water. {11} During the summer when
the ground is dry, they penetrate to a considerable depth and cease to
work, as they do during the winter when the ground is frozen. Worms are
nocturnal in their habits, and at night may be seen crawling about in
large numbers, but usually with their tails still inserted in their
burrows. By the expansion of this part of their bodies, and with the
help of the short, slightly reflexed bristles, with which their bodies
are armed, they hold so fast that they can seldom be dragged out of the
ground without being torn into pieces. {12} During the day they remain
in their burrows, except at the pairing season, when those which inhabit
adjoining burrows expose the greater part of their bodies for an hour or
two in the early morning. Sick individuals, which are generally affected
by the parasitic larv of a fly, must also be excepted, as they wander
about during the day and die on the surface. After heavy rain succeeding
dry weather, an astonishing number of dead worms may sometimes be seen
lying on the ground. Mr. Galton informs me that on one such occasion
(March, 1881), the dead worms averaged one for every two and a half paces
in length on a walk in Hyde Park, four paces in width. He counted no
less than 45 dead worms in one place in a length of sixteen paces. From
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