The Formation of Vegetable Mould Through the Action of Worms | Page 4

to the surface by worms in the form of castings. These castings are
sooner or later spread out and cover up any object left on the surface. I
was thus led to conclude that all the vegetable mould over the whole
country has passed many times through, and will again pass many
times through, the intestinal canals of worms. Hence the term "animal
mould" would be in some respects more appropriate than that
commonly used of "vegetable mould."
Ten years after the publication of my paper, M. D'Archiac, evidently
influenced by the doctrines of Elie de Beaumont, wrote about my
"singuliere theorie," and objected that it could apply only to "les

prairies basses et humides;" and that "les terres labourees, les bois, les
prairies elevees, n'apportent aucune preuve a l'appui de cette maniere
de voir." {3} But M. D'Archiac must have thus argued from inner
consciousness and not from observation, for worms abound to an
extraordinary degree in kitchen gardens where the soil is continually
worked, though in such loose soil they generally deposit their castings
in any open cavities or within their old burrows instead of on the
surface. Hensen estimates that there are about twice as many worms in
gardens as in corn-fields. {4} With respect to "prairies elevees," I do
not know how it may be in France, but nowhere in England have I seen
the ground so thickly covered with castings as on commons, at a height
of several hundred feet above the sea. In woods again, if the loose
leaves in autumn are removed, the whole surface will be found strewed
with castings. Dr. King, the superintendent of the Botanic Garden in
Calcutta, to whose kindness I am indebted for many observations on
earth-worms, informs me that he found, near Nancy in France, the
bottom of the State forests covered over many acres with a spongy
layer, composed of dead leaves and innumerable worm- castings. He
there heard the Professor of "Amenagement des Forets" lecturing to his
pupils, and pointing out this case as a "beautiful example of the natural
cultivation of the soil; for year after year the thrown-up castings cover
the dead leaves; the result being a rich humus of great thickness."
In the year 1869, Mr. Fish {5} rejected my conclusions with respect to
the part which worms have played in the formation of vegetable mould,
merely on account of their assumed incapacity to do so much work. He
remarks that "considering their weakness and their size, the work they
are represented to have accomplished is stupendous." Here we have an
instance of that inability to sum up the effects of a continually recurrent
cause, which has often retarded the progress of science, as formerly in
the case of geology, and more recently in that of the principle of
evolution.
Although these several objections seemed to me to have no weight, yet
I resolved to make more observations of the same kind as those
published, 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 10th, 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; {7} 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 with the kinds which bring up earth to the