the facts above given, it is not probable that these worms could have
been drowned, and if they had been drowned they would have perished in
their burrows. I believe that they were already sick, and that their
deaths were merely hastened by the ground being flooded.
It has often been said that under ordinary circumstances healthy worms
never, or very rarely, completely leave their burrows at night; but this
is an error, as White of Selborne long ago knew. In the morning, after
there has been heavy rain, the film of mud or of very fine sand over
gravel-walks is often plainly marked with their tracks. I have noticed
this from August to May, both months included, and it probably occurs
during the two remaining months of the year when they are wet. On these
occasions, very few dead worms could anywhere be seen. On January 31,
1881, after a long-continued and unusually severe frost with much snow,
as soon as a thaw set in, the walks were marked with innumerable tracks.
On one occasion, five tracks were counted crossing a space of only an
inch square. They could sometimes be traced either to or from the mouths
of the burrows in the gravel-walks, for distances between 2 or 3 up to 15
yards. I have never seen two tracks leading to the same burrow; nor is
it likely, from what we shall presently see of their sense-organs, that a
worm could find its way back to its burrow after having once left it.
They apparently leave their burrows on a voyage of discovery, and thus
they find new sites to inhabit.
Morren states {14} that worms often lie for hours almost motionless close
beneath the mouths of their burrows. I have occasionally noticed the
same fact with worms kept in pots in the house; so that by looking down
into their burrows, their heads could just be seen. If the ejected earth
or rubbish over the burrows be suddenly removed, the end of the worm s
body may very often be seen rapidly retreating. This habit of lying near
the surface leads to their destruction to an immense extent. Every
morning during certain seasons of the year, the thrushes and blackbirds
on all the lawns throughout the country draw out of their holes an
astonishing number of worms, and this they could not do, unless they lay
close to the surface. It is not probable that worms behave in this
manner for the sake of breathing fresh air, for we have seen that they
can live for a long time under water. I believe that they lie near the
surface for the sake of warmth, especially in the morning; and we shall
hereafter find that they often coat the mouths of their burrows with
leaves, apparently to prevent their bodies from coming into close contact
10