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by Charles Darwin,
LL.D., F.R.S.
Principles of Geology, by Charles Lyell
Silent Spring, by Rachel Carson
Table of
Contents:
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INTRODUCTION
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CHAPTER 1. 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
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CHAPTER 2. HABITS OF
WORMS—continued. Manner in which worms seize objects—Their power
of 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 burrows—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
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CHAPTER 3. 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
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CHAPTER 4. 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
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CHAPTER 5. THE ACTION OF
WORMS IN THE DENUDATION OF THE LAND. Evidence of the amount of
denudation which the land has undergone—Subaerial denudation—The
deposition of dust—Vegetable mould, its dark colour and fine texture
largely due to the action of worms—The disintegration of rocks by the
humus-acids—Similar acids apparently generated within the bodies of
worms—The action of these acids facilitated by the continued movement of
the particles of earth—A thick bed of mould checks the disintegration of
the underlying soil and rocks—Particles of stone worn or triturated in
the gizzards of worms—Swallowed stones serve as millstones—The levigated
state of the castings—Fragments of brick in the castings over ancient
buildings well rounded. The triturating power of worms not quite
insignificant under a geological point of view.
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CHAPTER 6. THE
DENUDATION OF THE LAND—continued. Denudation aided by recently
ejected castings flowing down inclined grass-covered surfaces—The amount
of earth which annually flows downwards—The effect of tropical rain on
worm castings—The finest particles of earth washed completely away from
castings—The disintegration of dried castings into pellets, and their
rolling down inclined surfaces—The formation of little ledges on
hill-sides, in part due to the accumulation of disintegrated
castings—Castings blown to leeward over level land—An attempt to
estimate the amount thus blown—The degradation of ancient encampments
and tumuli—The preservation of the crowns and furrows on land anciently
ploughed—The formation and amount of mould over the Chalk formation
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CHAPTER 7. CONCLUSION.
Summary of the part which worms have played in the history of the
world—Their aid in the disintegration of rocks—In the denudation of the
land—In the preservation of ancient remains—In the preparation of the
soil for the growth of plants—Mental powers of worms—Conclusion
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INDEX
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