CHAPTER VII--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.
Worms have played a more important part in the history of the world
than most persons would at first suppose. In almost all humid
countries they are extraordinarily numerous, and for their size
possess great muscular power. In many parts of England a weight of
more than ten tons (10,516 kilogrammes) of dry earth annually
passes through their bodies and is brought to the surface on each
acre of land; so that the whole superficial bed of vegetable mould
passes through their bodies in the course of every few years. From
the collapsing of the old burrows the mould is in constant though
slow movement, and the particles composing it are thus rubbed
together. By these means fresh surfaces are continually exposed to
the action of the carbonic acid in the soil, and of the humus-acids
which appear to be still more efficient in the decomposition of
rocks. The generation of the humus-acids is probably hastened
during the digestion of the many half-decayed leaves which worms
consume.
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