The Formation of Vegetable Mould, Through the Action of Worms, With Observations on Their Habits

by Darwin, Charles

• ISBN13: 9780898753141
• ISBN10: 0898753147
• Format: Paperback
• Copyright: 2001-04-01
• Publisher: Lightning Source Inc

Summary

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Table of Contents

Introduction	1	(7)
Habits of Worms	8	(47)
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
Habits of Worms	55	(74)
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
The Amount of Fine Earth Brought up by Worms to the Surface	129	(47)
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
The Part which Worms have Played in the Burial of Ancient Buildings	176	(54)
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 Beaulica Abbey
Roman villas at Chedworth and Brading
The remains of the Roman town at Silchester
The nature of the debris 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
The Action of Worms in the Denudation of the Land	230	(29)
Evidence of the amount of denudation which the sand 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
The Denudation of the Land	259	(46)
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
Conclusion	305	(10)
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
Index	315