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THE FORMATION
OF
VEGETABLE MOULD,
THROUGH THE
ACTION OF WORMS,
WITH
OBSERVATIONS ON THEIR HABITS.
BY
CHARLES DARWIN, LL. D., F. R. S.
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 atten-
tion-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 Cal-
careous concretions formed in the anterior pair of
glands-The calcareous matter primarily an excre-
tion, but secondarily serves to neutralise the acids.
generated during the digestive process 8-54
CHAPTER II.
HABITS OF WORMS-continued.
Manner in which worms seize objects-Their power
suction—The instinct of plugging up the mouths of
their burrows-Stones piled over the burrows-
The advantages thus gained-Intelligence shown by
worms in their manner of plugging up their burrows
-Various kinds of leaves and other objects thus
used-Triangles of paper-Summary of reasons for
believing that worms exhibit some intelligence-
Means by which they excavate their burrows, by
pushing away the earth and swallowing it-Earth
also swallowed for the nutritious matter which it
contains-Depth to which worms burrow, and the
construction of their brows--Burrows lined with
castings, and in the upper part with leaves--The
lowest part paved with little stones or seeds—
Manner in which the castings are ejected-The
collapse of old burrows-Distribution of worms—
Tower-like castings in Bengal-Gigantic castings
on the Nilgiri Mountains-Castings ejected in all
countries Page 55-128
CHAPTER III.
THE AMOUNT OF FINE EARTH BROUGHT UP BY WORMS
TO THE SURFACE.
Rate at which various objects strewed on the surface of
grass-fields are covered up by the castings of worms
-The burial of a paved path-The slow subsidence
of great stones left on the surface-The number of
worms which live within a given space-The
weight of earth ejected from a burrow, and from all
the burrows within a given space-The thickness
of the layer of mould which the castings on a given
space would form within a given time if uniformly
spread out-The slow rate at which mould can
increase to a great thickness-Conclusion
CHAPTER IV.
Page 129-175
THE PART WHICH WORMS HAVE PLAYED IN THE
BURIAL OF ANCIENT BUILDINGS.
The accumulation of rubbish on the sites of great cities
independent of the action of worms-The burial of
a Roman villa at Abinger-The floors and walls
penetrated by worms-Subsidence of a modern
pavement The buried pavement at Beaulieu Abbey
-Roman villas at Chedworth and Brading—The
remains of the Roman town at Silchester-The
nature of the débris by which the remains are
covered-The penetration of the tesselated floors
and walls by worms-Subsidence of the floors-
Thickness of the mould-The old Roman city of
Wroxeter-Thickness of the mould-Depth of the
foundations of some of the buildings--Conclusion
176-229
CHAPTER V.
THE ACTION OF WORMS IN THE DENUDATION OF
THE LAND.
Evidence of the amount of denudation which the land
has undergone-Subaerial denudation-The deposi-
tion of dust-Vegetable mould, its dark colour and