and to attack the problem on another side; namely, to weigh all the
castings thrown up within a given time in a measured space, instead of
ascertaining the rate at which objects left on the surface were buried by
worms. But some of my observations have been rendered almost superfluous
by an admirable paper by Hensen, already alluded to, which appeared in
1877. {6} Before entering on details with respect to the castings, it
will be advisable to give some account of the habits of worms from my own
observations and from those of other naturalists.
[FIRST EDITION,
_October_ 10_th_, 1881.]
CHAPTER I.
HABITS OF WORMS.
Nature of the sites inhabited Can live long under water Nocturnal Wander
about at night Often lie close to the mouths of their burrows, and are
thus destroyed in large numbers by birds Structure Do not possess eyes,
but can distinguish between light and darkness Retreat rapidly when
brightly illuminated, not by a reflex action Power of attention Sensitive
to heat and cold Completely deaf Sensitive to vibrations and to
touch Feeble power of smell Taste Mental qualities Nature of
food Omnivorous Digestion Leaves before being swallowed, moistened with a
fluid of the nature of the pancreatic secretion Extra-stomachal
digestion Calciferous glands, structure of Calcareous concretions formed
in the anterior pair of glands The calcareous matter primarily an
excretion, but secondarily serves to neutralise the acids generated
during the digestive process.
EARTH-WORMS are distributed throughout the world under the form of a few
genera, which externally are closely similar to one another. The British
species of Lumbricus have never been carefully monographed; but we may
judge of their probable number from those inhabiting neighbouring
countries. In Scandinavia there are eight species, according to Eisen;
{8a} but two of these rarely burrow in the ground, and one inhabits very
wet places or even lives under the water. We are here concerned only
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