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SELECTED WORKS OF
CHARLES DARWIN

*

WESTMINSTER EDITION

D. Appleton & Company

Charles Darwin's Study in his Residence at Down.
Kent County, England.

THE FORMATION
OF VEGETABLE
MOULD

THROUGH THE ACTION OF WORMS

By Charles Darwin

D. APPLETON AND COMPANY
NEW YORK AND LONDON

Authorized Edition.

Limited to one thousand copies ,
of which this is No

Introduction

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 re-
flex 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 second-
arily serves to neutralise the acids generated during the
digestive process . . . , , .8-

CHAPTER II.
habits of worms — continued.

Manner in which worms seize objects — Their power of suc-
tion— The instinct of plugging up the mouths of their
burrows — Stones piled over the burrows — The advan-

IV

CONTENTS.

PAGE

tages 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 exca-
vate their burrows, by pushing away the earth and swal-
lowing it — Earth also swallowed for the nutritious mat-
ter 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 • . . 56-130

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 — Con-
clusion 131-177

CHAPTER IV.

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

CONTENTS.

V

Roman villa at Abinger — The floors and walls pene-
trated by worms — Subsidence of a modern pavement —

The buried pavement at Beaulieu Abbey — Roman vil-
las 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 tessellated 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 — Conclu-
sion 178-232

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 deposition
of dust — Vegetable mould, its dark colour and fine
texture largely due to the action of worms — The dis-
integration of rocks by the humus-acids — Similar acids
apparently generated within the bodies of worms — The
action of these acids facilitated by the continued move-
ment 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 giz-
zards of worms — Swallowed stones serve as millstones
— The levigated state of the castings — Fragments of
brick in the castings over ancient buildings well round-
ed— The triturating power of worms not quite insig-
nificant under a geological point of view . . 233-261

CHAPTER VI.

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 trop-
ical rain on worm castings — The finest particles of earth

VI

CONTENTS.

washed completely away from castings — The disinte-
gration 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 disin-
tegrated 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 ...» 262-307/

CHAPTER VII.

CONCLUSION.

Summary of the part which worms have played in the his-
tory of the world — Their aid in the disintegration of
rocks — In the denudation of the land — In the preser-
vation of ancient remains — In the preparation of the
soil for the growth of plants — Mental powers of worms
— Conclusion . 308-316

Index

317-326

THE

FORMATION OF VEGETABLE MOULD,

THROUGH THE ACTION OF WORMS, WITH
OBSERVATIONS ON THEIR HABITS.

INTRODUCTION.

The share which worms have taken in the
formation pf the layer of vegetable mould,
which covers the whole surface of the land
in every moderately humid country, is the sub-
ject of the present volume. This mould is gen-
erally of a blackish colour and a few inches in
thickness. In different districts it differs but
little in appearance, although it may rest on
various subsoils. The uniform fineness of the
particles of which it is composed is one of its
chief characteristic features; and this may be
well observed in any gravelly country, where a
recently-ploughed field immediately adjoins

2

INTRODUCTION.

one which has long remained undisturbed for
pasture, and where the vegetable mould is ex-
posed on the sides of a ditch or hole. The
subject may appear an insignificant one, but
we shall see that it possesses some interest;
and the maxim “ de minimis lex non curat,”
does not apply to science. Even Elie de Beau-
mont, who generally undervalues small agen-
cies and their accumulated effects, remarks,*
“ la couche tres-mince de la terre vegetale est
un monument d’une haute antiquite, et, par le
fait de sa permanence, un objet digne d’oc-
cuper le geologue, et capable de lui fournir
des remarques interessantes.” Although the
superficial layer of vegetable mould as a whole
no doubt is of the highest antiquity, yet in re-
gard to its permanence, we shall hereafter see
reason to believe that its component particles
are in most cases removed at not a very slow
rate, and are replaced by others due to the dis-
integration of the underlying materials.

As I was led to keep in my study during
many months worms in pots filled with earth,
I became interested in them, and wished to

* “ Le9ons de Geologie Pratique,” tom. i. 1845, p. 140.

INTRODUCTION.

3

learn how far they acted consciously, and how
much mental power they displayed. I was
the more desirous to learn something on this
head, as few observations of this kind have
been made, as far as I know, on animals so
low in the scale of organization and so poorly
provided with sense-organs, as are earth-
worms.

In the year 1837, a short paper was read by
me before the Geological Society of London,*
“ On the Formation of Mould/’ in which it
was shown that small fragments of burnt marl,
cinders, &c., which had been thickly strewed
over the surface of several meadows, were
found after a few years lying at the depth of
some inches beneath the turf, but still forming
a layer. This apparent sinking of superficial
bodies is due, as was first suggested to me by
Mr. Wedgwood of Maer Hall in Staffordshire,
to the large quantity of fine earth continually
brought up to the surface by worms in the
form of castings. These castings are sooner
or later spread out and cover up any object

♦“Transactions Geolog. Soc.” vol. v. p. 505. Read No-
vember 1, 1837.

4

INTRODUCTION.

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 intes-
tinal canals of worms. Hence the term “ ani-
mal mould ” would be in some respects more
appropriate than that commonly used of “ veg-
etable mould.”

Ten years after the publication of my paper,
M. D’Archiac, evidently influenced by the doc-
trines 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.” *
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 contin-
ually 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. Von Hensen estimates that

* “ Histoire des progr&s de la G6ologie,” tom. i. 1847, p. 224.

INTRODUCTION.

5

there are about twice as many worms in gar-
dens as in corn-fields.* With respect to “ prai-
ries 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 sur-
face will be found strewed with castings. Dr.
King, the superintendent of the Botanic Gar-
den in Calcutta, to whose kindness I am in-
debted for many observations on earth-worms,
informs me that he found, near Nancy in
France, the bottom of the State forests cov-
ered 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/’

* “ Zeitschrift fur wissenschaft. Zoologie,” B. xxviii, 1877,

p. 361-

6

INTRODUCTION.

In the year 1869, Mr. Fish * rejected my
conclusions with respect to the part which
worms have played in the formation of vege-
table mould, merely on account of their as-
sumed incapacity to do so much work. He re-
marks 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 sci-
ence, as formerly in the case of geology, and
more recently in that of the principle of evolu-
tion.

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 ad-

* ‘‘Gardeners’ Chronicle,” April 17, 1869, p, 418.

INTRODUCTION.

7

mirable paper by Von Hensen, already alluded
to, which appeared in 1877. 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.

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 an-
other. 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

8

Chap. I.

SITES INHABITED.

9

to Eisen; * 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 surface in the form of castings.
Hoffmeister says that the species in Germany
are not well known, but gives the same num-
ber as Eisen, together with some strongly
marked varieties.f

Earth-worms abound in England in many
different stations. Their castings may be seen
in extraordinary numbers on commons and
chalk-downs, so as almost to cover the whole
surface, where the soil is poor and the grass
short and thin. But they are almost or quite
as numerous in some of the London parks,
where the grass grows well and the soil ap-
pears rich. Even on the same field worms are
much more frequent in some places than in
others, without any visible difference in the
nature of the soil. They abound in paved
court-yards close to houses; and an instance

* “ Bidrag till Skandinaviens Oligochsetfauna,” 1871.

f “ Die bis jetzt bekannten Arten aus der Familie der Re-
genwurmer,’, 1845.

io HABITS OF WORMS. Chap. I.

will be given in which they had burrowed
through the floor of a very damp cellar. I
have seen worms in black peat in a boggy
field; but they are extremely rare, or quite
absent in the drier, brown, fibrous peat, which
is so much valued by gardeners. On dry,
sandy or gravelly tracks, where heath with
some gorse, ferns, coarse grass, moss and lich-
ens alone grow, hardly any worms can be
found. But in many parts of England, wher-
ever a path crosses a heath, its surface becomes
covered with a fine short sward. Whether
this change of vegetation is due to the taller
plants being killed by the occasional trampling
of man and animals, or to the soil being occa-
sionally manured by the droppings from ani-
mals, I do not know.* On such grassy paths
worm-castings may often be seen. On a heath
in Surrey, which was carefully examined, there

* There is even some reason to believe that pressure is actually
favourable to the growth of grasses, for Professor Buckman, who
made many observations on their growth in the experimental
gardens of the Royal Agricultural College, remarks (“ Gardeners’
Chronicle,” 1854, p. 619) : “ Another circumstance in the culti-
vation of grasses in the separate form or small patches, is the
impossibility of rolling or treading them firmly, without which
no pasture can continue good.”

Chap. I.

SITES INHABITED.

II

were only a few castings on these paths, where
they were much inclined; but on the more
level parts, where a bed of fine earth had been
washed down from the steeper parts and had
accumulated to a thickness of a few inches,
worm-castings abounded. These spots seemed
to be overstocked with worms, so that they
had been compelled to spread to a distance of
a few feet from the grassy paths, and here their
castings had been thrown up among the heath;
but beyond this limit, not a single casting
could be found. A layer, though a thin one,
of fine earth, which probably long retains some
moisture, is in all cases, as I believe, necessary1*
for their existence; and the mere compas-
sion of the soil appears to be in some degree
favourable to them, for they often abound in
old gravel walks, and in foot-paths across
fields.

Beneath large trees few castings can be
found during certain seasons of the year, and
this is apparently due to the moisture having
been sucked out of the ground by the innu-
merable roots of the trees; for such places may
be seen covered with castings after the heavy

12

HABITS OF WORMS.

Chap. I.

autumnal rains. Although most coppices and
woods support many worms, yet in a forest of
tall and ancient beech-trees in Knole Park,
where the ground beneath was bare of all
vegetation, not a single casting could be found
over wide spaces, even during the autumn.
Nevertheless, castings were abundant on some
grass-covered glades and indentations which
penetrated this forest. On the mountains of
North Wales and on the Alps, worms, as I
have been informed, are in most places rare;
and this may perhaps be due to the close prox-
imity of the subjacent rocks, into which worms
cannot burrow during the winter so as to es-
cape being frozen. Dr. McIntosh, however,
found worm-castings at a height of 1500 feet
on Schiehallion in Scotland. They are numer-
ous on some hills near Turin at from 2000 to
3000 feet above the sea, and at a great altitude
on the Nilgiri Mountains in South India and
on the Himalaya.

Earth-worms must be considered as terres-
/rial animals, though they are still in one
sense semi-aquatic, like the other members of
the great class of annelids to which they be-

Chap. I.

NOCTURNAL.

13

long. M. Perrier found that their exposure
to the dry air of a room for only a single night
was fatal to them. On the other hand he kept
several large worms alive for nearly four
months, completely submerged in water.*
During the summer when the ground is dry,
they penetrate to a considerable depth and
cease to work, as they do during the winter
when the ground is frozen. Worms are noc^
turnal in their habits, and at night may be
seen crawling about in large numbers, but
usually with their tails still inserted in their
burrows. By the expansion of this part of
their bodies, and with the help of the short,
slightly reflexed bristles, with which their
bodies are armed, they hold so fast that they
can seldom be dragged out of the ground with-
out being torn into pieces. f During the day
they remain in their burrows, except at the
pairing season, when those which inhabit ad-

* I shall have occasion often to refer to M. Perrier’s admirable
memoir, “ Organisation des Lombriciens terrestres ” in “ Ar-
chives de Zoolog. exper.,” tom. iii. 1874, p. 372. C. F. Morren
(“ De Lumbrici terrestris,” 1829, p. 14) found that worms en-
dured immersion for fifteen to twenty days in summer, but
that in winter they died when thus treated.

f Morren, “ De Lumbrici terrestris,” &c., 1829, p. 67.

14

HABITS OF WORMS.

Chap. I.

joining burrows expose the greater part of
their bodies for an hour or two in the early
morning. Sick individuals, which are gener-
ally affected by the parasitic larvae of a fly,
must also be excepted, as they wander about
during the day and die on the surface. After
heavy rain succeeding dry weather, an aston-
ishing number of dead worms may sometimes
be seen lying on the ground. Mr. Galton in-
forms me that on one such occasion (March,
1881), the dead worms averaged one for every
two and a half paces in length on a walk in
Hyde Park, four paces in width. He counted
no less than 45 dead worms in one place in a
length of sixteen paces. From the facts above
given, it is not probable that these worms
could have been drowned, and if they had been
drowned they would have perished in their
burrows. I believe that they were already sick,
and that their deaths were merely hastened by
the ground being flooded.

It has often been said that under ordinary
circumstances healthy worms never, or very
rarely, completely leave their burrows at night;
but this is an error, as White of Selborne long

Chap. I. WANDER FROM THEIR BURROWS. 15

ago knew. In the morning, after there has
been heavy rain, the film of mud or of very
fine sand over gravel-walks is often plainly
marked with their tracks. I have noticed this
from August to May, both months included,
and it probably occurs during the two remain-
ing months of the year when they are wet.
On these occasions, very few dead worms
could anywhere be seen. On January 31,
1881, after a long-continued and unusually
severe frost with much snow, as soon as a
thaw set in, the walks were marked with innu-
merable tracks. On one occasion, five tracks
were counted crossing a space of only an inch
square. They could sometimes be traced either
to or from the mouths of the burrows in the
gravel-walks, for distances between 2 or 3 up
to 15 yards. I have never seen two tracks
leading to the same burrow; nor is it likely,
from what we shall presently see of their
sense-organs, that a worm could find its way
back to its burrow after having once left it.
They apparently leave their burrows on a voy-
age of discovery, and thus they find new sites
to inhabit.

i6

HABITS OF WORMS.

Chap. I.

Morren states * that worms often lie for
hours almost motionless close beneath the
mouths of their burrows. I have occasionally
noticed the same fact with worms kept in pots
in the house; so that by looking down into
their burrows, their heads could just be seen.
If the ejected earth or rubbish over the bur-
rows be suddenly removed, the end of the
worm's body may very often be seen rapidly
retreating. This habit of lying near the sur-
face leads to their destruction to an immense
extent. Every morning during certain seasons
of the year, the thrushes and blackbirds on all
the lawns throughout the country draw out
of their holes an astonishing number of worms;
and this they could not do, unless they lay
close to the surface. It is not probable that
worms behave in this manner for the sake of
breathing fresh air, for we have seen that they
can live for a long time under water. I be-
lieve that they lie near the surface for the sake
of warmth, especially in the morning; and we
shall hereafter find that they often coat the
mouths of their burrows with leaves, appar-

* “ De Lumbrici terrestris,” &c., p. 14.

Chap. I.

THEIR STRUCTURE.

1 7

ently to prevent thek bodies from coming into
close contact with the cold damp earth. It is
said that they completely close their burrows
during the winter.

Structure. — A few remarks must be made
on this subject. The body of a large worm
consists of from ioo to 200 almost cylindrical
rings or segments, each furnished with minute
bristles. The muscular system is well devel-
oped. Worms can crawl backwards as well
as forwards, and by the aid of their affixed tails
can retreat with extraordinary rapidity into
their burrows. The mouth is situated at the
anterior end of the body, and is provided with
a little projection (lobe or lip, as it has been
variously called) which is used for prehension.
Internally, behind the mouth, there is a strong
pharynx, shown in the accompanying dia-
gram (Fig. 1) which is pushed forwards when
the animal eats, and this part corresponds, ac-
cording to Perrier, with the protrudable trunk
or proboscis of other annelids. The pharynx
leads into the oesophagus, on each side of
which in the lower part there are three pairs
of large glands, which secrete a surprising

HABITS OF WORMS.

Chap. I.

Mouth.

Pharynx.

CEsophagus.

Calciferous

glands.

(Esophagus.

Crop.

Gizzard.

Upper part
of intestine.

Fig. i. — Diagram
of the alimentary
canal of an earth-
worm (Lumbri-
cus), copied from
Ray Lankesterin
“ Quart. Jour, of
Microscop. Soc.”
vol. xv. N.S. pi.
vii.

amount of carbonate of lime.
These calciferol^ glands are
highly remarkable, for nothing
like them is known in any other
animal. Their use will be dis-
cussed when we treat of the di-
gestive process. In most of
the species, the oesophagus is
enlarged into a crop in front of
the gizzard. This latter organ
is lined with a smooth thick
chitinous membrane, and is
surrounded by weak longitu-
dinal, but by powerful trans-
verse muscles. Perrier saw
these muscles in energetic ac-
tion; and, as he remarks, the
trituration of the food must be
chiefly effected by this organ,
for worms possess no jaws or
teeth of any kind. Grains of
sand and small stones, from the
to a little more than the Tff
inch in diameter, may generally
be found in their gizzards and

Chap. I.

THEIR SENSES.

19

intestines. As it is certain that worms swallow
many little stones, independently of those swal-
lowed while excavating their burrows, it is
probable that they serve, like mill-stones, to
triturate their food. The gizzard opens into
the intestine, which runs in a straight course
to the vent at the posterior end of the body.
The intestine presents a remarkable structure,
the typhosol^s, or, as the old anatomists called
it, an intestine within an intestine; and Clapa-
rede * has shown that this consists of a deep
longitudinal involution of the walls of the in-
testine, by which means an extensive absorb-
ent surface is gained.

The circulatory system is well developed.
Worms breathe by their skin, as they do not
possess any special respiratory organs. The
two sexes are united in the same individual, but
two individuals pair together. The nervous
system is fairly well developed; and the two
almost confluent cerebral ganglia are situated
very near to the anterior end of the body.

Senses. — Worms are destitute of eyes, and

* Histolog. Untersuchungen liber die Regenwiirmer. “ Zeit-
schrift fur wissenschaft. Zoologie,” B. xix., 1869, p. 61 1.

20

HABITS OF WORMS.

Chap. I.

at first I thought that they were quite insensi-
ble to light; for those kept in confinement
were repeatedly observed by the aid of a can-
dle, and others out of doors by the aid of a lan-
tern, yet they were rarely alarmed, although
extremely timid animals. Other persons have
found no difficulty in observing worms at night
by the same means.*

Hoffmeister, however, states f that worms,
with the exception of a few individuals, are
extremely sensitive to light; but he admits
that in most cases a certain time is requisite
for its action. These statements led me to
watch on many successive nights worms kept
in pots, which were protected from currents
of air by means of glass plates. The pots were
approached very gently, in order that no vi-
bration of the floor should be caused. When
under these circumstances worms were illu-
minated by a bull’s-eye lantern having slides
of dark red and blue glass, which intercepted
so much light that they could be seen only

* For instance, Mr. Bridgman and Mr. Newman (“The
Zoologist,” vol. vii. 1849, p. 2576), and some friends who ob-
served worms for me.

f “Familie der Regenwiirmer,” 1845, p. 18.

Chap. I.

THEIR SENSES.

21

with some difficulty, they were not at all af-
fected by this amount of light, however long
they were exposed to it. The light, as far as
I could judge^ was brighter than that from
the full moon. Its colour apparently made
no difference in the result. When they were
illuminated by a candle, or even by a bright
paraffin lamp, they were not usually affected
at first. Nor were they when the light was
alternately admitted and shut off. Sometimes,
however, they behaved very differently, for as
soon as the light fell on them, they withdrew
into their burrows with almost instantaneous
rapidity. This occurred perhaps once out of
a dozen times. When they did not withdraw
instantly, they often raised the anterior taper-
ing ends of their bodies from the ground, as if
their attention was aroused or as if surprise
was felt; or they moved their bodies from side

appeared distressed by the light; but I doubt
whether this was really the case, for on two
occasions after withdrawing slowly, they re-
mained for a long time with their anterior ex-
tremities protruding a little from the mouths

to side as if feeling for some object.

22

HABITS OF WORMS.

Chap. I.

of their burrows, in which position they were
ready for instant and complete withdrawal.

When the light from a candle was concen-
trated by means of a large lens on the anterior
extremity, they generally withdrew instantly;
but this concentrated light failed to act per-
haps once out of half a dozen trials. The light
was on one occasion concentrated on a worm
lying beneath water in a saucer, and it instant-
ly withdrew into its burrow. In all cases the
duration of the light, unless extremely feeble,
made a great difference in the result; for
worms left exposed before a paraffin lamp or a
candle invariably retreated into their burrows
within from five to fifteen minutes; and if in
the evening the pots were illuminated before
the worms had come out of their burrows, they
failed to appear.

H^Jom the foregoing facts it is evident that
light affects worms by its intensity and by
its duration. It is only the anterior ex-
tremity of the body, where the cerebral gan-
glia lie, which is affected by light, as Hoff-
meister asserts, and as I observed on many
occasions. If this part is shaded, other

Chap. I.

THEIR SENSES.

23

parts of the body may be fully illuminated,
and no effect will be produced. As these
animals have no eyes, we must suppose that
the light passes through their skins, and in
some manner excites their cerebral ganglia.
It appeared at first probable that the dif-
ferent manner in which they were affected on
different occasions might be explained, either
by the degree of extension of their skin and
its consequent transparency, or by some par-
ticular incidence of the light; but I could dis-
cover no such relation. One thing was mani-
fest, namely that when worms were employed
in dragging leaves into their burrows or in
eating them, and even during the short inter-
vals whilst they rested from their work, they
either did not perceive the light or were re-
gardless of it; and this occurred even when
the light was concentrated on them through
a large lens. So, again, whilst they are paired,
they will remain for an hour or two out of
their burrows, fully' exposed to the morning
light; but it appears from what Hoffmeister
says that a light will occasionally cause paired
individuals to separate.

24

HABITS OF WORMS.

Chap. I.

When a worm is suddenly illuminated and
dashes like a rabbit into its burrow — to use
the expression employed by a friend — we are
at first led to look at the action as a reflex one.
The irritation of the cerebral ganglia appears
to cause certain muscles to contract in an
inevitable manner, independently of the will
or consciousness of the animal, as if it were
an automaton. But the different effect which
a light produced on different occasions, and
especially the fact that a worm when in any
way employed and in the intervals of such em-
ployment, whatever set of muscles and gan-
glia may then have been brought into play, is
often regardless of light, are opposed to the
view of the sudden withdrawal being a sim-
ple reflex action. With the higher animals,
when close attention to some object leads to
the disregard of the impressions which other
objects must be producing on them, we at-
tribute this to their attention being then ab-
sorbed; and attention implies the presence of
a mind. Every sportsman knows that he can
approach animals whilst they are grazing,
fighting or courting, much more easily than

Chap. I. THEIR SENSES. 25

at other times. The state, also, of the nervous
system of* the higher animals differs much at
different times, for instance, a horse is much
more readily startled at one time than at an-
other. The comparison here implied between
the actions of one of the higher animals and
of one so low in the scale as an earth-worm,
may appear far-fetched; for we thus attribute
to the worm attention and some mental power,
nevertheless I can see no reason to doubt the
justice of the comparison.

Although worms cannot be said to possess
the power of vision, their sensitiveness to light
enables them to distinguish between day and
night; and they thus escape extreme danger
from the many diurnal animals which prey on
them. Their withdrawal into their burrows
during the day appears, however, to have be-
come an habitual action; for worms kept in
pots covered by glass-plates, over which sheets
of black paper were spread, and placed before
a north-east window, remained during the day-
time in their burrows and came out every
night; and they continued thus to act for a

week. No doubt a little light may have en-
3

2 6

HABITS OF WORMS.

Chap. I.

terecl between the sheets of glass and the black-
ened paper; but we know from the trials with
coloured glass, that worms are indifferent to
a small amount of light.

Worms appear to be less sensitive jo mod-
erate radiant heat than to a bright light. I
judge of this from having held at different
times a poker heated to dull redness near some
worms, at a distance which caused a very sen-
sible degree of warmth in my hand. One of
them took no notice; a second withdrew into
its burrow, but not quickly; the third and
fourth much more quickly, and the fifth as
quickly as possible. The light from a candle,
concentrated by a lens and passing through
a sheet of glass which would intercept most of
the heat-rays, generally caused a much more
rapid retreat than did the heated poker.
Worms are sensitive to a low temperature, as
may be inferred from their not coming out of
their burrows during a frost. I

Worms do not possess any sense of War-
ing. They took not the least notice of the
shrill notes from a metal whistle, which was re-
peatedly sounded near them; nor did they of

Chap. I.

THEIR SENSES.

27

the deepest and loudest tones of a bassoon.
They were indifferent to shouts, if care was
taken that the breath did not strike them.
When placed on a table close to the keys of
a piano, which was played as loudly as pos-
sible, they remained perfectly quiet.

Although they are indifferent to undula-
tions in the air audible by us, they are ex-
tremely sensitive to vibratioffs in any solid
object. When the pots containing two worms
which had remained quite indifferent to the
sound of the piano, were placed on this instru-
ment, and the note C in the bass clef was
struck, both instantly retreated into their bur-
rows. After a time they emerged, and when
G above the line in the treble clef was struck
they again retreated. Under similar circum-
stances on another night one worm dashed
into its burrow on a very high note being
struck only once, and the other worm when
C in the treble clef was struck. On these oc-
casions the worms were not touching the sides
of the pots, which stood in saucers; so that
the vibrations, before reaching their bodies,
had to pass from the sounding board of the

28

HABITS OF WORMS.

Chap. I.

piano, through the saucer, the bottom of the
pot and the damp, not very compact earth on
which they lay with their tails in their burrows.
They often showed their sensitiveness when
the pot in which they lived, or the table on
which the pot stood, was accidentally and
lightly struck; but they appeared less sensi-
tive to such jars than to the vibrations of the
piano; and their sensitiveness to jars varied
much at different times. It has often been
said that if the ground is beaten or otherwise
made to tremble, worms believe that they are
pursued by a mole and leave their burrows.
I beat the ground in many places where worms
abounded, but not one emerged. When, how-
ever, the ground is dug with a fork and is vio-
lently disturbed beneath a worm, it will often
crawl quickly out of its burrow.

The whole body of a worm is sensitive to
contact. A slight puff of air from the mouth
causes an instant retreat. The glass plates
placed over the pots did not fit closely, and
blowing through the very narrow chinks thus
left, often sufficed to cause a rapid retreat.
They sometimes perceived the eddies in the

Chap. I.

THEIR SENSES.

29

air caused by quickly removing the glass
plates. When a worm first comes out of its
burrow, it generally moves the much extended
anterior extremity of its body from side to
side in all directions, apparently as an organ
of touch; and there is some reason to believe,
as we shall see in the next chapter, that they
are thus enabled to gain a general notion of the
form of an object. Of all their senses that of
touch, including in this term the perception
of a vibration, seems much the most highly de-
veloped.

In worms the sense of smell apparently is
confined to the perception orcertain odours,
and is feeble. They were quite indifferent to
my breath, as long as I breathed on them very
gently. This was tried, because it appeared
possible that they might thus be warned of
the approach of an enemy. They exhibited
the same indifference to my breath whilst I
chewed some tobacco, and while a pellet of
cotton-wool with a few drops of mille-fleurs
perfume or of acetic acid was kept in my
mouth. Pellets of cotton-woo? soaked in to-
bacco juice, and in mille-fleurs perfume, and

30

HABITS OF WORMS.

Chap. I.

in paraffin, were held with pincers and were
waved about within two or three inches of
several worms, but they took no notice. On
one or two occasions, however, when acetic
acid had been placed on the pellets, the worms
appeared a little uneasy, and this was prob-
ably due to the irritation of their skins. The
perception of such unnatural odours would
be of no service to worms; and as such timid
creatures would almost certainly exhibit some
signs of any new impression, we may conclude
that they did not perceive these odours.

The result was different when cabbage-
leaves and pieces of onion were employed,
both of which are devoured with much relish
by worms. Small square pieces of fresh and
half-decayed cabbage-leaves and of onion
bulbs were on nine occasions buried in my
pots, beneath about \ of an inch of common
garden soil; and they were always discovered
by the worms. One bit of cabbage was dis-
covered and removed in the course of two
hours; three were removed by the next morn-
ing, that is, after a single night; two others
after two nights; and the seventh bit after

Chap. I.

THEIR SENSES.

31

three nights* Two pieces of onion were dis-
covered and removed after three nights. Bits
of fresh raw meat, of which worms are very
fond, were buried, and were not discovered
within forty-eight hours, during which time
they had not become putrid. The earth above
the various buried objects was generally
pressed down only slightly, so as not to pre-
vent the emission of any odour. On two oc-
casions, however, the surface was well watered,
and was thus rendered somewhat compact.
After the bits of cabbage and onion had been
removed, I looked beneath them to see wheth-
er the worms had accidentally come up from
below, but there was no sign of a burrow;
and twice the buried objects were laid on
pieces of tin-foil which were not in the least
displaced. It is of course possible that the
worms whilst moving about on the surface of
the ground, with their tails affixed within their
burrows, may have poked their heads into the
places where the above objects were buried;
but I have never seen worms acting in this
manner. Some pieces of cabbage-leaf and of
onion were twice buried beneath very fine fer-

32

HABITS OF WORMS.

Chap. I.

ruginous sand, which was slightly pressed
down and well watered, so as to be rendered
very compact, and these pieces were never dis-
covered. On a third occasion the same kind
of sand was neither pressed down nor watered,
and the pieces of cabbage were discovered and
removed after the second night. These several
facts indicate that worms possess some power
of smell; and that they discover by this means
odoriferous and much-coveted kinds of food.

It may be presumed that all animals which
feed on various substances posse<^ the sense
of taste, and this is certainly the case with
worms. Cabbage-leaves are much liked by
worms; and it appears that they can distin-
guish between different varieties; but this may
perhaps be owing to differences in their tex-
ture. On eleven occasions pieces of the fresh
leaves of a common green variety and of the
red variety used for pickling were given them,
and they preferred the green, the red being
either wholly neglected or much less gnawed.
On two other occasions, however, they seemed
to prefer the red. Half-decayed leaves of the
red variety and fresh leaves of the green were

Chap. I.

THEIR SENSES.

33

attacked about equally. When leaves of the
cabbage, horse-radish (a favourite food) and
of the onion were given together, the latter
were always and manifestly preferred. Leaves
of the cabbage, lime-tree, Ampelopis, parsnip
(Pastinaca), and celery (Apium) were likewise
given together; and those of the celery were
first eaten. But when leaves of cabbage,
turnip, beet, celery, wild cherry and carrots
were given together, the two latter kinds, espe-
cially those of the carrot, were preferred to all
the others, including those of celery. It was
also manifest after many trials that wild cherry
leaves were greatly preferred to those of the
lime-tree and hazel (Corylus). According to
Mr. Bridgman the half-decayed leaves of Phlox
verna are particularly liked by worms.*

Pieces of the leaves of cabbage, turnip,
horse-radish and onion were left on the pots
during 22 days, and were all attacked and had
to be renewed; but during the whole of this
time leaves of an Artemisia and of the culinary
sage, thyme and mint, mingled with the above
leaves, were quite neglected excepting those

* “ The Zoologist,” vol. vii. 1849, p. 2576.

34

HABITS OF WORMS.

Chap. I.

of the mint, which were occasionally and very
slightly nibbled. These latter four kinds of
leaves do not differ in texture in a manner
which could make them disagreeable to
worms; they all have a strong taste, but so
have the four first mentioned kinds of leaves;
and the wide difference in the result must be
attributed to a preference by the worms for
one taste over another.

Mental Qualities. — There is little to be said
on this head. We have seen that worms are
timid. It may be doubted whether they suffer
as much pain when injured, as they seem to
express by their contortions. Judging by their
eagerness for certain kinds of food, they must
enjoy the pleasure of eating. Their sexual
passion is strong enough to overcome for a
time their dread of light. They perhaps have
a trace of social feeling, for they are not dis-
turbed by crawling over each other’s bodies,
and they sometimes lie in contact. According
to Hoffmeister they pass the winter either sin-
gly or rolled up with others into a ball at the
bottom of their burrows.* Although worms

* “Familie der Regenwiirmer,” p. 13.

Chap. I.

MENTAL QUALITIES.

35

are so remarkably deficient in the several sense-
organs, this does not necessarily preclude in-
telligence, as we know from such cases as those
of Laura Bridgman; and we have seen that
when their attention is engaged, they neglect
impression to which they would otherwise
have attended; and attention indicates the
presence of a mind of some kind. They are
also much more easily excited at certain times
than at others. They perform a few actions
instinctively, that is, all the individuals, includ-
ing the young, perform such actions in nearly
the same fashion. This is shown by the man-
ner in which the species of Perichaeta eject
their castings, so as to construct towers; also
by the manner in which the burrows of the
common earth-worm are smoothly lined with
fine earth and often with little stones, and the
mouths of their burrows with leaves. One of
their strongest instincts is the plugging up the
mouths of their burrows with various objects;
and very young worms act in this manner.
But some degree of intelligence appears, as we
shall see in the next chapter, to be exhibited
in this work, — a result which has surprised

36 HABITS OF WORMS. Chap. I.

me more than anything else in regard to
worms.

Food and Digestion. — Worms are omnivo-
rous. They swallow an enormous quantity of
earth, out of which they extract any digesti-
ble matter which it may contain; but to this
subject I must recur. They also consume a
large number of half-decayed leaves of all
kinds, excepting a few which have an unpleas-
ant taste or are too tough for them; likewise
petioles, peduncles and decayed flowers. But
they will also consume fresh leaves, as I have
found by repeated trials. According to Mor-
ren * they will eat particles of sugar and liquor-
ice; and the worms which I kept drew many
bits of dry starch into their burrows, and a
large bit had its angles well rounded by the
fluid poured out of their mouths. But as they
often drag particles of soft stone, such as of
chalk, into their burrows, I feel some doubt
whether the starch was used as food. Pieces
of raw and roasted meat were fixed several
times by long pins to the surface of the soil in
my pots, and night after night the worms

* “ De Lumbrici terrestris p. 19.

Chap. I.

FOOD AND DIGESTION.

37

could be seen tugging at them, with the edges
of the pieces engulfed in their mouths, so that
much was consumed. Raw fat seems to be
preferred even to raw meat or to any other
substance which was given them, and much
was consumed. They are cannibals, for the
two halves of a dead worm placed in two of
the pots were dragged into the burrows and
gnawed; but as far as I could judge, they pre-
fer fresh to putrid meat, and in so far I differ
from Hoffmeister.

Leon Fredericq states * that the digestive
fluid of worms is of the same nature as the
pancreatic secretion of the higher animals;
and this conclusion agrees perfectly with the
kinds of food which worms consume. Pan-
creatic juice emulsifies fat, and we have just
seen how greedily worms devour fat; it dis-
solves fibrin, and worms eat raw meat; it con-
verts starch into grape-sugar with wonderful
rapidity, and we shall presently show that the
digestive fluid of worms acts on starch. f But

* “ Archives de Zoologie experimentale,” tom. vii, 1878,
P* 394.

f On the action of the pancreatic ferment, see “ A Text-Book
of Physiology,” by Michael Foster, 2nd edit. pp. 198-203. 1878.

78 / HABITS OF WORMS. Chap. I.

/

the>k/live chiefly on half-decayed leaves; and
these would be useless to them unless they
could digest the cellulose forming the cell-
walls; for it is well known that all other nutri-
tious substances are almost completely with-
drawn from leaves, shortly before they fall off.
It has, however, now been ascertained that
cellulose, though very little or not at all at-
tacked by the gastric secretion of the higher
animals, is acted on by that from the pan-
creas.*

The half-decayed or fresh leaves which
worms intend to devour, are dragged into the
mouths of their burrows to a depth of from
one to three inches, and are then moistened
with a secreted fluid. It has been assumed
that this fluid serves to hasten their decay; but
a large number of leaves were twice pulled
out of the burrows of worms and kept for
many weeks in a very moist atmosphere under
a bell-glass in my study; and the parts which
had been moistened by the worms did not de-
cay more quickly in any plain manner than the

* Schmulewitsch, Action des Sues digestifs sur la Cellulose.
“ Bull, de l’Acad. Imp. de St. Petersbourg,” tom. xxv. p. 549.
1879.

Chap. I.

FOOD AND DIGESTION.

39

other parts. When fresh leaves were given in
the evening to worms kept in confinement and
examined early on the next morning, therefore
not many hours after they had been dragged
into the burrows, the fluid with which they
were moistened, when tested with neutral
litmus paper, showed an alkaline reaction.
This was repeatedly found to be the case with
celery, cabbage and turnip leaves. Parts of
the same leaves which had not been moistened
by the worms, were pounded with a few drops
of distilled water, and the juice thus extracted
was not alkaline. Some leaves, however,
which had been drawn into burrows out of
doors, at an unknown antecedent period, were
tried, and though still moist, they rarely ex-
hibited even a trace of alkaline reaction.

The fluid, with which the leaves are bathed,
acts on them whilst they are fresh or nearly
fresh, in a remarkable manner; for it quickly
kills and discolours them. Thus the ends of
a fresh carrot-leaf, which had been dragged
into a burrow, were found after twelve hours
of a dark brown tint. Leaves of celery, turnip,
maple, elm, lime, thin leaves of ivy, and oc-

40

HABITS OF WORMS.

Chap. I.

casionally those of the cabbage were similarly
acted on. The end of a leaf of Triticum repens,
still attached to a growing plant, had been
drawn into a burrow, and this part was dark
brown and dead, whilst the rest of the leaf
was fresh and green. Several leaves of lime
and elm removed from burrows out of doors
were found affected in different degrees. The
first change appears to be that the veins be-
come of a dull reddish-orange. The cells with
chlorophyll next lose more or less completely
their green colour, and their contents finally
become brown. The parts thus affected often
appeared almost black by reflected light; but
when viewed as a transparent object under the
microscope, minute specks of light were trans-
mitted, and this was not the case with the un-
affected parts of the same leaves. These ef-
fects, however, merely show that the secreted
fluid is highly injurious or poisonous to leaves;
for nearly the same effects were produced in
from one to two days on various kinds of
young leaves, not only by artificial pancreatic
fluid, prepared with or without thymol, but
quickly by a solution of thymol by itself. On

Chap. I.

FOOD AND DIGESTION.

41

one occasion leaves of Corylus were much dis-
coloured by being kept for eighteen hours in
pancreatic fluid, without any thymol. With
young and tender leaves immersion in human
saliva during rather warm weather, acted in
the same manner as the pancreatic fluid, but
not so quickly. The leaves in all these cases
often became infiltrated with the fluid.

Large leaves from an ivy plant growing
on a wall were so tough that they could not
be gnawed by worms, but after four days they
were affected in a peculiar manner by the se-
cretion poured out of their mouths. The
upper surfaces of the leaves, over which the
worms had crawled, as was shown by the dirt
left on them, were marked in sinuous lines,
by either a continuous or broken chain of
whitish and often star-shaped dots, about 2
mm. in diameter. The appearance thus pre-
sented was curiously like that of a leaf, into
which the larva of some minute insect had
burrowed. But my son Francis, after making
and examining sections, could nowhere find
that the cell-walls had been broken down or
that the epidermis had been penetrated.

42

HABITS OF WORMS.

Chap. I.

When the section passed through the whitish
dots, the grains of chlorophyll were seen to
be more or less discoloured, and some of the
palisade and mesophyll cells contained noth-
ing but broken down granular matter. These
effects must be attributed to the transudation
of the secretion through the epidermis into the
cells.

The secretion with which worms moisten
leaves likewise acts on the starch granules
within the cells. My son examined some
leaves of the ash and many of the lime, which
had fallen off the trees and had been partly
dragged into worm-burrows. It is known that
with fallen leaves the starch-grains are pre-
served in the guard-cells of the stomata. Now
in several cases the starch had partially or
wholly disappeared from these cells, in the
parts which had been moistened by the secre-
tion; while they were still well preserved in the
other parts of the same leaves. Sometimes
the starch was dissolved out of only one of the
two guard-cells. The nucleus in one case had
disappeared, together with the starch-granules.
The mere burying of lime-leaves in damp earth

Chap. I.

FOOD AND DIGESTION.

43

for nine days did not cause the destruction of
the starch-granules. On the other hand, the
immersion of fresh lime and cherry leaves for
eighteen hours in artificial pancreatic fluid, led
to the dissolution of the starch-granules in the
guard-cells as well as in the other cells.

From the secretion with which the leaves
are moistened being alkaline, and from its
acting both on the starch-granules and on the
protoplasmic contents of the cells, we may
infer that it resembles in nature not saliva,*
but pancreatic secretion; and we know from
Fredericq that a secretion of this kind is found

in the intestines of worms. As the leaves

V

which are dragged into the burrows are often
dry and shrivelled, it is indispensable for their
disintegration by the unarmed mouths of
worms that they should first be moistened and
softened; and fresh leaves, however soft and
tender they may be, are similarly treated, prob-
ably from habit. The result is that they are
partially digested before they are taken into
the alimentary canal. I any not aware of any

* Claparede doubts whether saliva is secreted by worms : see
“ Zeitschrift fiir wissenschaft. Zoologie,” B. xix. 1869, p. 601.

44

HABITS OF WORMS.

Chap. L

other case of extra-stomachal digestion hav-
ing been recorded. The boa-constrictor bathes
its prey with saliva, but this is solely for lubri-
cating it. Perhaps the nearest analogy may
be found in such plants as Drosera and Di-
onaea; for here animal matter is digested and
converted into peptone not within a stomach,
but on the surfaces of the leaves.

Calciferous Glands. — These glands (see
Fig. i), judging from their size and from their
rich supply of blood-vessels, must be of much
importance to the animal. But almost as
many theories have been advanced on their
use as there have been observers. They con-
sist of three pairs, which in the common earth-
worm debouch into the alimentary canal in
advance of the gizzard, but posteriorly to it
in Urochtaea and some other genera.* The
two posterior pairs are formed by lamellae,
which according to Claparede, are diverticula
from the oesophagus. f These lamellae are

coated with a pulpy cellular layer, with the

* Perrier, “ Archives de Zoolog. exper.,” July, 1874, pp. 416,
419.

f “ Zeitschrift fiir wissenschaft. Zoologie,” B. xix. 1869, pp.
603-606.

Chap. I.

CALCIFEROUS GLANDS.

45

outer cells lying free in infinite numbers. If
one of these glands is punctured and squeezed,
a quantity of white pulpy matter exudes, con-
sisting of these free cells. They are minute,
and vary in diameter from 2 to 6 ^ They
contain in their centres a little excessively fine
granular matter; but they look so like oil glob-
ules that Claparede and others at first treated
them with ether. This produces no effect; but
they are quickly dissolved with effervescence
in acetic acid, and when oxalate of ammonia is
added to the solution a white precipitate is
thrown down. We may therefore conclude
that they contain carbonate <\y lime. If the
cells are immersed in a very little acid, they
become more transparent, look like ghosts,
and are soon lost to view; but if much acid
is added, they disappear instantly. After a
very large number have been dissolved, a floc-
culent residue is left, which apparently con-
sists of the delicate ruptured cell-walls. In
the two posterior pairs of glands the carbonate
of lime contained in the cells occasionally ag-
gregates into small rhombic crystals or into
concretions, which lie between the lamellae;

46

HABITS OF WORMS.

Chap. I.

but I have seen only one, and Claparede only
a very few such cases.

The two anterior glands differ a little in
shape from the four posterior ones, by being
more oval. They differ also conspicuously in
generally containing several small, or two or
three larger, or a single very large concretion
of carbonate of lime, as much as ijmm. in
diameter. When a gland includes only a few
very small concretions, or, as sometimes hap-
pens, none at all, it is easily overlooked. The
large concretions are round or oval, and exte-
riorly almost smooth. One was found which
filled up not only the whole gland, as is often
the case, but its neck; so that it resembled an
olive-oil flask in shape. These concretions
when broken are seen to be more or less crys-
talline in structure. How they escape from the
gland is a marvel; but that they do escape is
certain, for they are often found in the gizzard,
intestines, and in the castings of worms, both
with those kept in confinement and those in a
state of nature.

Claparede says very little about the struc-
ture of the two anterior glands, and he sup-

Chap. I.

CALCIFEROUS GLANDS.

47

poses that the calcareous matter of which the
concretions are formed is derived from the
four posterior glands. But if an anterior gland
which contains only small concretions is placed
in acetic acid and afterwards dissected, or if
sections are made of such a gland without
being treated with acid, lamellae like those in
the posterior glands and coated with cellular
matter could be plainly seen, together with a
multitude of free calciferous cells readily solu-
ble in acetic acid. When a gland is completely
filled with a single large concretion, there are
no free cells, as these have been all consumed
in forming the concretion. But if such a con-
cretion, or one of only moderately large size
is dissolved in acid, much membranous matter
is left, which appears to consist of the remains
of the formerly active lamellae. After the
formation and expulsion of a large concretion,
new lamellae must be developed in some man-
ner. In one section made by my son, the
process had apparently commenced, although
the gland contained two rather large concre-
tions, for near the walls several cylindrical and
oval pipes were intersected, which were lined

48

HABITS OF WORMS.

Chap. I.

with cellular matter and were quite filled with
free calciferous cells. A great enlargement in
one direction of several oval pipes would give
rise to the lamellae.

Besides the free calciferous cells in which
no nucleus was visible, other and rather larger
free cells were seen on three occasions; and
these contained a distinct nucleus and nucle-
olus. They were only so far acted on by acetic
acid that the nucleus was thus rendered more
distinct. A very small concretion was removed
from between two of the lamellae within an
anterior gland. It was embedded in pulpy
cellular matter, with many free calciferous
cells, together with a multitude of the larger,
free, nucleated cells, and these latter cells were
not acted on by acetic acid, while the former
were dissolved. From this and other such
cases I am led to suspect that the calciferous
cells are developed from the larger nucleated
ones; but how this is effected was not ascer-
tained.

When an anterior gland contains several
minute concretions, some of these are general-
ly angular or crystalline in outline, while the

Chap. I.

CALCIFEROUS GLANDS.

49

greater number are rounded .with an irregu-
lar mulberry-like surface. Calciferous cells ad-
hered to many parts of these mulberry-like
masses, and their gradual disappearance could
be traced while they still remained attached.
It was thus evident that the concretions are
formed from the lime contained within the
free calciferous cells. As the smaller concre-
tions increase in size, they come into contact
and unite, thus enclosing the now functionless
lamellae; and by such steps the formation of
the largest concretions could be followed.
Why the process regularly takes place in the
two anterior glands, and only rarely in the
four posterior glands is quite unknown.
Morren says that these glands disappear dur-
ing the winter; and I have seen some instances
of this fact, and others in which either the an-
terior or posterior glands were at this season
so shrunk and empty, that they could be dis-
tinguished only with much difficulty.

With respect to the function of the cal-
ciferous glands, it is prqbafble that they pri-
marily serve as organs of excretion, and sec-
ondarily as an aid to digestion. Worms con-

50

HABITS OF WORMS.

Chap. I.

sume many fallen leaves; and it is known that
lime goes on accumulating in leaves until they
drop off the parent-plant, instead of being re-
absorbed into the stem or roots, like various
other organic and inorganic substances.* The
ashes of a leaf of an acacia have been known
to contain as much as 72 per cent, of lime.
Worms therefore would be liable to become
charged with this earth, unless there were some
special means for its excretion; and the cal-
ciferous glands are well adapted for this pur-
pose. The worms which live in mould close
over the chalk, often have their intestines filled
with this substance, and their castings are al-
most white. Here it is evident that the supply
of calcareous matter must be superabundant.
Nevertheless with several worms collected on
such a site, the calciferous glands contained
as many free calciferous cells, and fully as many
and large concretions, as did the glands of
worms which lived where there was little or
no lime; and this indicates that the lime is an
excretion, and not a secretion poured into the
alimentary canal for some special purpose.

* De Vries, “ Landwirth. Jahrbiicher,” 1881, p. 77.

Chap. I.

CALCIFEROUS GLANDS.

51

On the other hand, the following consid-
erations render it highly probable that the car-
bonate of lime, which is excreted by th^^lands,
aids the digestive process unde£ ordinary cir-
cumstances. Leaves during their decay gen-
erate an abundance of various kinds of acids,
which have been grouped together under the
term of humus acids. We shall have to recur
to this subject in our fifth chapter, and I need
here only say that these acids act strongly on
carbonate of lime. The half-decayed leaves
which are swallowed in such large quantities
by worms would, therefore, after they have
been moistened and triturated in the alimen-
tary canal, be apt to produce such acids. And
in the case of several worms, the contents of
the alimentary canal were found to be plainly
acid, as shown by litmus paper. This acidity
cannot be attributed to the nature of the di-
gestive fluid, for pancreatic fluid is alkaline;
and we have seen that the secretion which is
poured out of the mouths of worms for the
sake of preparing the leaves for consumption,
is likewise alkaline. The acidity can hardly be
due to uric acid, as the contents of the upper

52

HABITS OF WORMS.

Chap. I.

part of the intestine were often acid. In one
case the contents of the gizzard were slightly
acid, those of the upper intestines being more
plainly acid. In another case the contents of
the pharynx were not acid, those of the giz-
zard doubtfully so, while those of the intestine
were distinctly acid at a distance of 5 cm.
below the gizzard. Even with the higher
herbivorous and omnivorous animals, the con-
tents of the large intestine are acid. “ This,
however, is not caused by any acid secretion
from the mucous membrane; the reaction of
the intestinal walls in the larger as in the small
intestine is alkaline. It must therefore arise
from acid fermentations going on in the con-
tents themselves. ... In Carnivora the con-
tents of the caecum are said to be alkaline, and
naturally the amount of fermentation will de-
pend largely on the nature of the food.” *
With worms not only the contents of the
intestines, but their ejected matter or the cast-
ings, are generally acid. Thirty castings from
different places were tested, and with three or

* M. Foster, “ A Text-Book of Physiology,” 2nd edit. 1878,
P- 243.

Chap. I.

CALCIFEROUS GLANDS.

53

four exceptions were found to be acid; and
the exceptions may have been due to such
castings not having been recently ejected; for
some which were at first acid, were on the fol-
lowing morning, after being dried and again
moistened, no longer acid; and this probably
resulted from the humus acids being, as is
known to be the case, easily decomposed. Five
fresh castings from worms which lived in
mould close over the chalk, were of a whitish
colour and abounded with calcareous matter;
and these were not in the least acid. This
shows how effectually carbonate of lime neu-
tralises the intestinal acids. When worms were
kept in pots filled with fine ferruginous sand,
it was manifest that the oxide of iron, with
which the grains of silex were coated, had been
dissolved and removed from them in the cast-
ings.

The digestive fluid of worms resembles in
its action, as already stated, the pancreatic
secretion of the higher animals; and in these
latter, “ pancreatic digestion is essentially alka-
line; the action will not take place unless some
alkali be present; and the activity of an alka-

54

HABITS OF WORMS.

Chap. I.

line juice is arrested by acidification, and hin-
dered by neutralization.” * Therefore it seems
highly probable that the innumerable calciier-
ous cells, which are poured from the foiir pos-
terior glands into the alimentary canal of
worms, serve to neutralise more or less com-
pletely the acids there generated Not the half-
decayed leaves. We have seen that these cells
are instantly dissolved by a small quantity of
acetic acid, and as they do not always suffice to
neutralise the contents of even the upper part
of the alimentary canal, the lime is perhaps
aggregated into concretions in the anterior
pair of glands, in order that some may be car-
ried down to the posterior parts of the intes-
tine, where these concretions would be rolled
about amongst the acid contents. The con-
cretions found in the intestines and in the
castings often have a worn appearance, but
whether this is due to some amount of attri-
tion or of chemical corrosion could not be told.
Claparede believes that they are formed for
the sake of acting as mill-stones, and of thus
aiding in the trituration of the food. They

* M. Foster, Ibid. p. 200.

Chap. I.

CALCIFEROUS GLANDS.

55

may give some aid in this way; but I fully agree
with Perrier that this must be of quite subor-
dinate importance, seeing that the object is
already attained by stones being generally
present in the gizzards and intestines of worms.

CHAPTER II.

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 swal-
lowing 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.

In the pots in which worms were kept,
leaves were pinned down to the soil, and at
night the manner in which they were seized
could be observed. The worms always en-
deavoured to drag the leaves towards their
burrows; and they tore or sucked off small

fragments, whenever the leaves were sufficient-

56

Chap. II. THEIR MANNER OF PREHENSION. 57

ly tender. They generally seized the thin edge
of a leaf with their mouths, between the pro-
jecting upper and lower lip; the thick and
strong pharynx being at the same time, as
Perrier remarks, pushed forward within their
bodies, so as to afford a point of resistance for
the upper lip. In the case of broad flat ob-
jects they acted in a wholly different manner.
The pointed anterior extremity of the body,
after being brought into contact with an ob-
ject of this kind, was drawn within the adjoin-
ing rings, so that it appeared truncated and be-
came as thick as the rest of the body. This
part could then be seen to swell a little; and
this, I believe, is due to the pharynx being
pushed a little forwards. Then by a slight
withdrawal of the pharynx or by its expansion,
a vacuum was produced beneath the truncated
slimy end of the body whilst in contact with
the object; and by this means the two adhered
firmly together.* That under these circum-
stances a vacuum was produced was plainly

* Clapar&de remarks (“ Zeitschrift fur wissenschaft. Zoolog.”
B. 19, 1869, p. 602) that the pharynx appears from its structure
to be adapted for suction.

5

58

HABITS OF WORMS.

Chap. II.

seen on one occasion, when a large worm
lying beneath a flaccid cabbage leaf tried to
drag it away; for the surface of the leaf di-
rectly over the end of the worm’s body became
deeply pitted. On another occasion a worm
suddenly lost its hold on a flat leaf; and the an-
terior end of the body was momentarily seen
to be cup-formed. Worms can attach them-
selves to an object beneath water in the same
manner; and I saw one thus dragging away a
submerged slice of an onion-bulb.

The edges of fresh or nearly fresh leaves
affixed to the ground were often nibt^ed by
the worms; and sometimes the epidermis and
all the parenchyma on one side was gnawed
completely away over a considerable space;
the epidermis alone on the opposite side being
left quite clean. The veins were never touched,
and leaves were thus sometimes partly con-
verted into skeletons. As worms have no
teeth and as their mouths consist of very soft
tissue, it may be presumed that they consume
by means of suction the edges aqd the par-
enchyma of fresh leaves, after they^^ave been
softened by the digestive fluid. They cannot

Chap. II. PROTECTION OF THEIR BURROWS. 59

attack such strong leaves as those of sea-kale
or large and thick leaves of ivy; though one
of the latter after it had become rotten was
reduced in parts to the state of a skeleton.

Worms seize leaves and other objects, not
only to serve as food, but for plugging up the
mouths of their burrows; and this is one of
their strongest instincts. Leaves and petioles
of many kinds, some flower-peduncles, often
decayed twigs of trees, bits of paper, feathers,
tufts of wool and horse-hairs are dragged into
their burrows for this purpose. I have seen
as many as seventeen petioles of a Clematis
projecting from the mouth of one burrow, and
ten from the mouth of another. Some of these
objects, such as the petioles just named, feath-
ers, &c., are never gnawed by worms. In a
gravel walk in my garden I found many hun-
dred leaves of a pine-tree (P. austriaca or
nigricans) drawn by their bases into burrows.
The surfaces by which these leaves are articu-
lated to the branches are shaped in as pecul-
iar a manner as is the joint between the leg-
bones of a quadruped; and if these surfaces
had been in the least gnawed, the fact would

6o

HABITS OF WORMS.

Chap. II.

have been immediately visible, but there was
no trace of gnawing. Of ordinary dicotyle-
donous leaves, all those which are dragged
into burrows are not gnawed. I have seen as
many as nine leaves of the lime-tree drawn
into the same burrow, and not nearly all of
them had been gnawed; but such leaves may
serve as a store for future consumption.
Where fallen leaves are abundant, many more
are sometimes collected over the mouth of a
burrow than can be used, so that a small pile
of unused leaves is left like a roof over those
which have been partly dragged in.

A leaf in being dragged a little way into
a cylindrical burrow is necessarily much folded
or crumpled. When another leaf is drawn in,
this is done exteriorly to the first one, and so
on with the succeeding leaves; and finally all
become closely folded and pressed together.
Sometimes the worm enlarges the mouth of
its burrow, or makes a fresh one close by, so
as to draw in a still larger number of leaves.
They often or generally fill up the interstices
between the drawn-in leaves with moist viscid
earth ejected from their bodies, and thus the

Chap. II. PROTECTION OF THEIR BURROWS. 6 1

mouths of the burrows are securely plugged.
Hundreds of such plugged burrows may be
seen in many places, especially during the
autumnal and early winter months. But, as
will hereafter be shown, leaves are dragged
into the burrows not only for plugging them
up and for food, but for the sake of lining the
upper part or mouth.

When worms cannot obtain leaves, peti-
oles, sticks, &c., with which to plug up the
mouths of their burrows, they often protect
them by little heaps of stones; and such heaps
of smooth rounded pebbles may frequently be
seen on gravel-walks. Here there can be no
question about food. A lady, who was inter-
ested in the habits of worms, removed the little
heaps of stones from the mouths of several
burrows and cleared the surface of the ground
for some inches all round. She went out on
the following night with a lantern, and saw
the worms with their tails fixed in their bur-
rows, dragging the stones inwards by the aid
of their mouths, no doubt by suction. “ After
two nights some of the holes had 8 or 9 small
stones over them; after four nights one had

62

HABITS OF WORMS.

Chap. II.

about 30, and another 34 stones.” * One
stone which had been dragged over the gravel-
walk to the mouth of a burrow weighed two
ounces; and this proves how strong worms
are. But they show greater strength in some-
times displacing stones in a well-trodden
gravel-walk; that they do so, may be inferred
from the cavities left by the displaced stones
being exactly filled by those lying over the
mouths of adjoining burrows, as I have my-
self observed.

Work of this kind is usually performed
during the night; but I have occasionally
known objects to be drawn into the burrows
during the day. What advantage the worms
derive from plugging up the mouths of their
burrows with leaves, &c., or from piling
stones over them, is doubtful. They do not
act in this manner at the times when they
eject much earth from their burrows; for their
castings then serve to cover the mouth.
When gardeners wish to kill worms on a lawn,
it is necessary first to brush or rake away the

* An account of her observations is given in the “ Gardeners’
Chronicle,” March 28th, 1868, p. 324.

Chap. II. PROTECTION OF THEIR BURROWS. 63

castings from the surface, in order that the
lime-water may enter the burrows.* It might
be inferred from this fact that the mouths are
plugged up with leaves, &c., to prevent the
entrance of water during heavy rain; but it
may be urged against this view that a few,
loose, well-rounded stones are ill-adapted to
keep out water. I have moreover seen many
burrows in the perpendicularly cut turf-edg-
ings to gravel-walks, into which water could
hardly flow, as well plugged as burrows on a
level surface. Can the plugs or piles of stones
aid in concealing the burrows from scolopen-
ders, which, according to Hoffmeister,f are
the bitterest enemies of worms? Or may not
worms when thus protected be able to remain
with safety with their heads close to the
mouths of their burrows, which we know that
they like to do, but which costs so many of
them their lives? Or may not the plugs check
the free ingress, of the lowest stratum of air,
when chilled by radiation at night, from the
surrounding ground and herbage. I am in-

* London’s “ Gard. Mag.,” xvii. p. 216, as quoted in the
“Catalogue of the British Museum Worms,” 1865, p. 327.

f “Familie der Regenwiirmer,” p. 19.

6 4

HABITS OF WORMS.

Chap. II.

dined to believe in this latter view; firstly, be-
cause when worms were kept in pots in a
room with a fire, in which case cold air could
not enter the burrows, they plugged them up
in a slovenly manner; and secondarily, because
they often coat the upper part of their bur-
rows with leaves, apparently to prevent their
bodies from coming into close contact with
the cold damp earth. But the plugging-up
process may perhaps serve for all the above
purposes.

Whatever the motive may be, it appears
that worms much dislike leaving the mouths
of their burrows open. Nevertheless they will
reopen them at night, whether or not they
can afterwards close them. Numerous open
burrows may be seen on recently-dug ground,
for in this case the worms eject their castings
in cavities left in the ground, or in the old bur-
rows, instead of piling them over the mouths
of their burrows, and they cannot collect ob-
jects on the surface by which the mouths
might be protected. So again on a recently
disinterred pavement of a Roman villa at
Abinger (hereafter to be described) the worms

Chap. II.

THEIR INTELLIGENCE.

65

pertinaciously opened their burrows almost
every night, when these had been closed by
being trampled on, although they were rarely
able to find a few minute stones wherewith to
protect them.

Intelligence shown
ner of plugging up their burrows . — If a man had
to plug up a small cylindrical hole, with such
objects as leaves, petioles or twigs, he would
drag or push them in by their pointed ends;
but if these objects were very thin relatively
to the size of the hole, he would probably in-
sert some by their thicker or broader ends.
The guide in his case would be intelligence.
It seemed therefore worth while to observe
carefully how worms dragged leaves into their
burrows; whether by their tips or bases or
middle parts. It seemed more especially de-
sirable to do this in the case of plants not na-
tives to our country; for although the habit
of dragging leaves into their burrows is un-
doubtedly instinctive with worms, yet instinct
could not tell them how to act in the case of
leaves about which their progenitors knew
nothing. If, moreover, worms acted solely

worms in their man-

66

HABITS OF WORMS.

Chap. II.

through instinct or an unvarying inherited im-
pulse, they would draw all kinds of leaves into
their burrows in the same manner. If they
have no such definite instinct, we might ex-
pect that chance would determine whether the
tip, base or middle was seized. If both these
alternatives are excluded, intelligence alone is
left; unless the worm in each case first tries
many different methods, and follows that alone
which proves possible or the most easy; but to
act in this manner and to try different meth-
ods makes a near approach to intelligence.

In the first place 227 withered leaves of
various kinds, mostly of English plants, were
pulled out of worm-burrows in several places.
Of these, 181 had been drawn into the bur-
rows by or near their tips, so that the foot-
stalk projected nearly upright from the mouth
of the burrow; 20 had been drawn in by their
bases, and in this case the tips projected from
the burrows; and 26 had been seized near the
middle, so that these had been drawn in trans-
versely and were much crumpled. Therefore
80 per cent, (always using the nearest whole
number) had been drawn in by the tip, 9 per

Chap. II.

THEIR INTELLIGENCE.

67

cent, by the base or footstalk, and 1 1 per cent,
transversely or by the middle. This alone is
almost sufficient to show that chance does not
determine the manner in which leaves are
dragged into the burrows.

Of the above 227 leaves, 70 consisted of
the fallen leaves of the common lime-tree,
which is almost certainly not a native of Eng-
land. These leaves are much acuminated to-
wards the tip, and are very broad at the base
with a well-developed foot-stalk. They are
thin and quite flexible when half-withered. Of
the 70, 79 per cent, had been drawn in by or
near the tip; 4 per cent, by or near the base;
and 17 per cent, transversely or by the mid-
dle. These proportions agree very closely, as
far as the tip is concerned, with those before
given. But the percentage drawn in by the
base is smaller, which may be attributed to
the breadth of the basal part of the blade.
We here, also, see that the presence of a foot-
stalk, which it might have been expected would
have tempted the worms as a convenient
handle, has little or no influence in determin-
ing the manner in which lime leaves are

68

HABITS OF WORMS.

Chap. II.

dragged into the burrows. The considerable
proportion, viz., 17 per cent., drawn in more
or less transversely depends no doubt on the
flexibility of these half-decayed leaves. The
fact of so many having been drawn in by the
middle, and of some few having been drawn
in by the base, renders it improbable that the
worms first tried to draw in most of the leaves
by one or both of these methods, and that
they afterwards drew in 79 per cent, by their
tips; for it is clear that they would not have
failed in drawing them in by the base or
middle.

The leaves of a foreign plant were next
searched for, the blades of which were not
more pointed towards the apex than towards
the base. This proved to be the case with
those of a laburnum (a hybrid between
Cytisus alpinus and laburnum ) for on doubling
the terminal over the basal half, they gener-
ally fitted exactly; and when there was any
difference, the basal half was a little the nar-
rower. It might, therefore, have been ex-
pected that an almost equal number of these
leaves would have been drawn in by the tip

Chap. II. THEIR INTELLIGENCE. 69

and base, or a slight excess in favour of the
latter. But of 73 leaves (not included in the
first lot of 227) pulled out of worm-burrows,
63 per cent, had been drawn in by the tip; 27
per cent, by the base, and 10 per cent, trans-
versely. We here see that a far larger pro-
portion, viz., 27 per cent, were drawn in by
the base than in the case of lime leaves, the
blades of which are very broad at the base,
and of which only 4 per cent, had thus been
drawn in. We may perhaps account for the
fact of a still larger proportion of the laburnum
leaves not having been drawn in by the base,
by worms having acquired the habit of gen-
erally drawing in leaves by their tips and thus
avoiding the foot-stalk. For the basal mar-
gin of the blade in many kinds of leaves forms
a large angle with the foot-stalk; and if such
a leaf were drawn in by the foot-stalk, the
basal margin would come abruptly into con-
tact with the ground on each side of the bur-
row, and would render the drawing in of the
leaf very difficult.

Nevertheless worms break through their
habit of avoiding the foot-stalk, if this part

yo HABITS OF WORMS. Chap. II.

offers them the most convenient means for
drawing leaves into their burrows. The leaves
of the endless hybridised varieties of the
Rhododendron vary much in shape; some are
narrowest towards the base and others to-
wards the apex. After they have fallen off,
the blade on each side of the midrib often be-
comes curled up while drying, sometimes along
the whole length, sometimes chiefly at the
base, sometimes towards the apex. Out of 28
fallen leaves on one bed of peat in my garden,
no less than 23 were narrower in the basal
quarter than in the terminal quarter of their
length; and this narrowness was chiefly due to
the curling in of the margins. Out of 36 fallen
leaves on another bed, in which different varie-
ties of the Rhododendron grew, only 17 were
narrower towards the base than towards the
apex. My son William, who first called my
attention to this case, picked up 237 fallen
leaves in his garden (where the Rhododendron
grows in the natural soil) and of these 65 per
cent, could have been drawn by worms into
their burrows more easily by the base or foot-
stalk than by the tip; and this was partly due

Chap. II.

THEIR INTELLIGENCE.

71

to the shape of the leaf and in a less degree to
the curling in of the margins: 27 per cent,
could have been drawn in more easily by the
tip than by the base: and 8 per cent, with about
equal ease by either end. The shape of a fallen
leaf ought to be judged of before one end has
been drawn into a burrow, for after this has
happened, the free end, whether it be the base
or apex, will dry more quickly than the end
embedded in the damp ground; and the ex-
posed margins of the free end will consequent-
ly tend to become more curled inwards than
they were when the leaf was first seized by the
worm. My son found 91 leaves which had
been dragged by worms into their burrows,
though not to a great depth; of these 66 per
cent, had been drawn in by the base or foot-
stalk; and 34 per cent, by the tip. Jn this case,
therefore, the worms judged with a consider-
ble degree of correctness how b^st to draw the
withered leaves of this foreign plant into their
burrows; notwithstanding that they had to de-
part from their usual h^bit of avoiding the
foot-stalk.

On the gravel-walks in my garden a very

72

HABITS OF WORMS.

Chap. II.

large number of leaves of three species of
Pinus ( P . austriaca, nigricans and sylvestris )
are regularly drawn into the mouths of worm-
burrows. These leaves consist of two needles,
which are of considerable length in the two
first and short in the last named species, and
are united to a common base; and it is by this
part that they are almost invariably drawn
into the burrows. I have seen only two or
at most three exceptions to this rule with
worms in a state of nature. As the sharply
pointed needles diverge a little, and as several
leaves are drawn into the same burrow, each
tuft forms a perfect chevaux de frise. On two
occasions many of these tufts were pulled up
in the evening, but by the following morning
fresh leaves had been pulled in, and the bur-
rows were again well protected. These leaves
could not be dragged into the burrows to any
depth, except by their bases, as a worm can-
not seize hold of the two needles at the same
time, and if one alone were seized by the
apex, the other would be pressed against the
ground and would resist the entry of the seized
one. This was manifest in the above men-

Chap. II.

THEIR INTELLIGENCE.

73

tioned two or three exceptional cases. In
order, therefore, that worms should do their
work well, they must drag pine-leaves into
their burrows by their bases, where the two
needles are conjoined. But how they are
guided in this work is a perplexing question.

This difficulty led my son Francis and my-
self to observe worms in confinement during
several nights by the aid of a dim light, while
they dragged the leaves of the above named
pines into their burrows. They moved the
anterior extremities of their bodies about the
leaves, and on several occasions when they
touched the sharp end of a needle they with-
drew suddenly as if pricked. But I doubt
whether they were hurt, for they are indiffer-
ent to very sharp objects, and will swallow even
rose-thorns and small splinters of glass. It
may also be doubted, whether the sharp ends
of the needles serve to tell them that this is
the wrong end to seize; for the points were
cut off many leaves for a length of about one
inch, and fifty-seven of them thus treated were
drawn into the burrows by their bases, and not

one by the cut-off ends. The worms in con-
6

74 HABITS OF WORMS. Chap. II.

finement often seized the needles near the mid-
dle and drew them towards the mouths of
their burrows; and one worm tried in a sense-
less manner to drag them into the burrow by
bending them. They sometimes collected
many more leaves over the mouths of their
burrows (as in the case formerly mentioned of
lime-leaves) than could enter them. On other
occasions, however, they behaved very differ-
ently; for as soon as they touched the base of
a pine-leaf, this was seized, being sometimes

*

completely engulfed in their mouths, or a point
very near the base was seized, and the leaf was
then quickly dragged or rather jerked into
their burrows. It appeared both to my son
and myself as if the worms instantly perceived
as soon as they had seized a leaf in the proper
manner. Nine such cases were observed, but
in one of them the worm failed to drag the leaf
into its burrow, as it was entangled by other
leaves lying near. In another case a leaf stood
nearly upright with the points of the needles
partly inserted into a burrow, but how placed
there was not seen; and then the worm reared
itself up and seized the base, which was

Chap. II.

THEIR INTELLIGENCE.

75

dragged into the mouth of the burrow by bow-
ing the whole leaf. On the other hand, after
a worm had seized the base of a leaf, this was
on two occasions relinquished from some un-
known motive.

As already remarked, the habit of plugging
up the mouths of the burrows with various
objects, is no doubt instinctive in worms; and
a very young one, born in one of my pots,
dragged for some little distance a Scotch-fir
leaf, one needle of which was as long and al-
most as thick as its own body. No species of
pine is endemic in this part of England, it is
therefore incredible that the proper manner of
dragging pine-leaves into the burrows can be
instinctive with our worms. But as the worms
on which the above observations were made,
were dug up beneath or near some pines, which
had been planted there about forty years, it
was desirable to prove that their actions were
not instinctive. Accordingly, pine-leaves were
scattered on the ground in places far removed
from any pine-tree, and 90 of them were drawn
into the burrows by their bases. Only two
were drawn in by the tips of the needles, and

76 HABITS OF WORMS. Chap. II.

these were not real exceptions, as one was
drawn in for a very short distance, and the
two needles of the other cohered. Other pine-
leaves were given to worms kept in pots in a
warm room, and here the result was different;
for out of 42 leaves drawn into the burrows,
no less than 16 were drawn in by the tips of
the needles. These worms, however, worked
in a careless or slovenly manner; for the leaves
were often drawn in to only a small depth;
sometimes they were merely heaped over the
mouths of the burrows, and sometimes none
were drawn in. I believe that this carelessness
may be accounted for by the air of the room
being warm, and the worms consequently not
being anxious to plug up their holes effectual-
ly. Pots tenanted by worms and covered with
a net which allowed the entrance of cold air,
were left out of doors for several nights, and
now 72 leaves were all properly drawn in by
their bases.

It might perhaps be inferred from the facts
as yet given, that worms somehow gain a gen-
eral notion of the shape or structure of pine-
leaves, and perceive that it is necessary for

Chap. II. THEIR INTELLIGENCE. 77

them to seize the base where the two needles
are conjoined. But the following cases make
this more than doubtful. The tips of a large
number of needles of P. austriaca were ce-
mented together with shell-lac dissolved in al-
cohol, and were kept for some days, until, as
I believe, all odour or taste had been lost; and
they were then scattered on the ground where
no pine-trees grew, near burrows from which
the plugging had been removed. Such leaves
could have been drawn into the burrows with
equal ease by either end; and judging from
analogy and more especially from the case
presently to be given of the petioles of Clematis
montana , I expected that the apex would have
been preferred. But the result was that out
of 12 1 leaves with the tips cemented, which
were drawn into burrows, 108 were drawn in
by their bases, and only 13 by their tips.
Thinking that the worms might possibly per-
ceive and dislike the smell or taste of the shell-
lac, though this was very improbable, especial-
ly after the leaves had been left out during
several nights, the tips of the needles of many
leaves were tied together with fine thread. Of

78

HABITS OF WORMS.

Chap. II.

leaves thus treated 150 were drawn into bur-
rows— 123 by the base and 27 by the tied tips;
so that between four and five times as many
were drawn in by the base as by the tip. It is
possible that the short cut-off ends of the
thread with which they were tied, may have
tempted the worms to drag in a larger propor-
tional number by the tips than when cement
was used. Of the leaves with tied and ce-
mented tips taken together (271 in number)
85 per cent, were drawn in by the base and
15 per cent, by the tips. We may therefore
infer that it is not the divergence of the two
needles which leads worms in a state of nature
almost invariably to drag pine-leaves into their
burrows by the base. Nor can it be the sharp-
ness of the points of the needles which deter-
mines them; for, as we have seen, many leaves
with the points cut off were drawn in by their
bases. We are thus led to conclud^ that with
pine-leaves there must be somethin'g attractive
to worms in the base, notwithstanding that
few ordinary leaves are drawn in by the base
or foot-stalk.

Petioles. — We will now turn to the petioles

Chap. II.

THEIR INTELLIGENCE.

79

or foot-stalks of compound leaves, after the
leaflets have fallen off. Those from Clematis
montana , which grew over a verandah, were
dragged early in January in large numbers
into the burrows on an adjoining gravel-walk,
lawn, and flower-bed. These petioles vary
from 2\ to 4^ inches in length, are rigid and
of nearly uniform thickness, except close to
the base where they thicken rather abruptly,
being here about twice as thick as in any other
part. The apex is somewhat pointed, but
soon withers and is then easily broken, off. Of
these petioles, 314 were pulled out of burrows
in the above specified sites; and it was found
that 76 per cent, had been drawn in by their
tips, and 24 per cent, by their bases; so that
those drawn in by the tip were a little more
than thrice as many as those drawn in by the
base. Some of those extracted from the well-
beaten gravel-walk were kept separate from
the others; and of these (59 in number) nearly
five times as many had been drawn in by the
tip as by the base; whereas of those extracted
from the lawn and flower-bed, where from the
soil yielding more easily, less care would be

8o

HABITS OF WORMS.

Chap. II.

necessary in plugging up the burrows, the
proportion of those drawn in by the tip (130)
to those drawn in by the base (48) was rather
less than three to one. That these petioles had
been dragged into the burrows for plugging
them up, and not for food, was manifest, as
neither end, as far as I could see, had been
gnawed. As several petioles are used to plug
up the same burrow, in one case as many as
10, and in another case as many as 15, the
worms may perhaps at first draw in a few by
the thicker end so as to save labour; but after-
wards a large majority are drawn in by the
pointed end, in order to plug up the hole se-
curely.

The fallen petioles of our native ash-tree
were next observed, and the rule with most
objects, viz., that a large majority are dragged
into the burrows by the more pointed end, had
not here been followed; and this fact much
surprised me at first. These petioles vary in
length from 5 to 8| inches; they are thick
and fleshy towards the base, whence they
taper gently towards the apex, which is a little
enlarged and truncated where the terminal

Chap. II.

THEIR INTELLIGENCE.

8l

leaflet had been originally attached. Under
some ash-trees growing in a grass-field, 229
petioles were pulled out of worm burrows early
in January, and of these 51.5 per cent, had
been drawn in by the base, and 48.5 per cent,
by the apex. This anomaly was however
readily explained as soon as the thick basal
part was examined; for in 78 out of 103 peti-
oles, this part had been gnawed by worms, just
above the horse-shoe shaped articulation. In
most cases there could be no mistake about
the gnawing; for ungnawed petioles which
were examined after being exposed to the
weather for eight additional weeks had not
become more disintegrated or decayed near
the base than elsewhere. It is thus evident
that the thick basal end of the petiole is
drawn in not solely for the sake of plugging
up the mouths of the burrows, but as food.
Even the narrow truncated tips of some few
petioles had been gnawed; and this was the
case in 6 out of 37 which were examined for
this purpose. Worms, after having drawn in
and gnawed the basal end, often push the peti-
oles out of their burrows; and then drag in

82

HABITS OF WORMS.

Chap. II.

fresh ones, either by the base for food, or by
the apex for plugging up the mouth more ef-
fectually. Thus, out of 37 petioles inserted by
their tips, 5 had been previously drawn in by
the base, for this part had been gnawed.
Again, I collected a handful of petioles lying
loose on the ground close to some plugged-up
burrows, where the surface was thickly strewed
with other petioles which apparently had
never been touched by worms; and 14 out
of 47 (i. e. nearly one-third), after having had
their bases gnawed had been pushed out of
the burrows and were now lying on the
ground. From these several facts we may
conclude that worms draw in some petioles
of the ash by the base to serve as food, and
others by the tip to plug up the mouths
of their burrows in the most efficient man-
ner.

The petioles of Robinia pseudo-acacia vary
from 4 or 5 to nearly 12 inches in length; they
are thick close to the base before the softer
parts have rotted off, and taper much towards
the upper end. They are so flexible that I
have seen some few doubled up and thus

THEIR INTELLIGENCE.

Chap. II.

83

drawn into the burrows of worms. Unfor-
tunately these petioles were not examined
until February, by which time the softer parts
had completely rotted off, so that it was im-
possible to ascertain whether worms had

gnawed the bases, though this is in itself

probable. Out of 12 1 petioles extracted from
burrows early in February, 68 were embedded
by the base, and 53 by the apex. On

February 5 all the petioles which had been

drawn into the burrows beneath a Robinia,
were pulled up ; and after an interval of
eleven days, 35 petioles had been again
dragged in, 19 by the base, and 16 by the
apex. Taking these two lots together, 56 per
cent, were drawn in by the base, and 44 per
cent, by the apex. As all the softer parts had
long ago rotted off, we may feel sure, espe-
cially in the latter case, that none had been
drawn in as food. At this season, therefore,
worms drag these petioles into their burrows
indifferently by either end, a slight preference
being given to the base. This latter fact may
be accounted for by the difficulty of plugging
up a burrow with objects so extremely thin

84

HABITS OF WORMS.

Chap. II.

as are the upper ends. In support of this view,
it may be stated that out of the 16 petioles
which had been drawn in by their upper ends,
the more attenuated terminal portion of 7
had been previously broken off by some ac-
cident.

Triangles of paper. — Elongated triangles
were cut out of moderately stiff writing-paper,
which wras rubbed with raw fat on both sides,
so as to prevent their becoming excessively
limp when exposed at night to rain and dew.
The sides of all the triangles were three
inches in length, with the bases of 120 one
inch, and of the other 183 half an inch in
length. These latter triangles were very nar-
row or much acuminated.* As a check on
the observations presently to be given, simi-
lar triangles in a damp state wTere seized by a
very narrow pair of pincers at different points
and at all inclinations with reference to the
margins, and were then drawn into a short
tube of the diameter of a worm-burrow. If

* In these narrow triangles the apical angle is g° 34', and the
basal angles 85° 13'. In the broader triangles the apical angle
is 190 10' and the basal angles 8o° 25'.

Chap. II. THEIR INTELLIGENCE. 85

seized by the apex, the triangle was drawn
straight into the tube, with its margins in-
folded; if seized at some little distance from
the apex, for instance at half an inch, this
much was doubled back within the tube. So
it was with the base and basal angles, though
in this case the triangles offered, as might have
been expected, much more resistance to being
drawn in. If seized near the middle the tri-
angle was doubled up, with the apex and base
left sticking out of the tube. As the sides of
the triangles were three inches in length, the
result of their being drawn into a tube or into
a burrow in different ways, may be conven-
iently divided into three groups: those drawn
in by the apex or within an inch of it; those
drawn in by the base or within an inch of it;
and those drawn in by any point in the middle
inch.

In order to see how the triangles would be
seized by worms, some in a damp state were
given to worms kept in confinement. They
were seized in three different manners in the
case of both the narrow and broad triangles:
viz., by the margin; by one of the three angles,

86

HABITS OF WORMS.

Chap. II.

which was often completely engulfed in their
mouths; and lastly, by suction applied to any
part of the flat surface. If lines parallel to the
base and an inch apart, are drawn across a
triangle with the sides three inches in length,
it will be divided into three parts of equal
length. Now if worms seized indifferently by
chance any part, they would assuredly seize
on the basal part or division far oftener than
on either of the two other divisions. For the
area of the basal to the apical part is as 5 to
1, so that the chance of the former being drawn
into a burrow by suction, will be as 5 to 1,
compared with the apical part. The base of-
fers two angles and the apex only one, so that
the former would have twice as good a chance
(independently of the size of the angles) of
being engulfed in a worm’s mouth, as would
the apex. It should, however, be stated that
the apical angle is not often seized by worms;
the margin at a little distance on either side
being preferred. I judge of this from having
found in 40 out of 46 cases in which triangles
had been drawn into furrows by their apical
ends, that the tip had been doubled back

Chap. II. THEIR INTELLIGENCE. 87

within the burrow for a length of between
-gVth of an inch and 1 inch. Lastly, the pro-
portion between the margins of the basal and
apical parts is as 3 to 2 for the broad, and to
2 for the narrow triangles. From these several
considerations it might certainly have been
expected, supposing that worms seized hold of
the triangles by chance, that a considerably
larger proportion would have been dragged
into the burrows by the basal than by the apical
part; but we shall immediately see how differ-
ent was the result.

Triangles of the above specified sizes were
scattered 011 the ground in many places and
on many successive nights near worm-bur-
rows, from which the leaves, petioles, twigs,
&c., with which they had been plugged, were
removed. Altogether 303 triangles were
drawn by worms into their burrows: 12 others
were drawn in by both ends, but as it was im-
possible to judge by which end they had been
first seized, these are excluded. Of the 303,
62 per cent, had been drawn in by the apex
(using this term for all drawn in by the apical
part, one inch in length); 15 per cent, by the

88

HABITS OF WORMS.

Chap. II.

middle; and 23 per cent, by the basal part. If
they had been drawn indifferently by any
point, the proportion for the apical, middle and
basal parts would have been 33.3 per cent, for
each; but, as we have just seen, it might have
been expected that a much larger proportion
would have been drawn in by the basal than
by any other part. As the case stands, nearly
three times as many were drawn in by the apex
as by the base. If we consider the broad tri-
angles by themselves, 59 per cent, were drawn
in by the apex, 25 per cent, by the middle, and
16 per cent, by the base. Of the narrow tri-
angles, 65 per cent, were drawn in by the
apex, 14 per cent, by the middle, and 21 per
cent, by the base; so that here those drawn in
by the apex were more than 3 times as many
as those drawn in by the base. We may there-
fore conclude that the manner in which the
triangles are drawn into the burrows is not a
matter of chance.

In eight cases, two triangles had been
drawn into the same burrow, and in seven of
these cases, one had been drawn in by the
apex and the other by the base. This again

Chap. II.

THEIR INTELLIGENCE.

89

indicates that the result is not determined by
chance. Worms appear sometimes to revolve
in the act of drawing in the triangles, for five
out of the whole lot had been wound into an
irregular spire round the inside of the burrow.
Worms kept in a warm room drew 63 tri-
angles into their burrows; but, as in the case
of the pine-leaves, they worked in a rather
careless manner, for only 44 per cent, were
drawn in by the apex, 22 per cent, by the mid-
dle, and 33 per cent, by the base. In five
cases, two triangles were drawn into the same
burrow.

It may be suggested with much apparent
probability that so large a proportion of the
triangles were drawn in by the apex, not from
the worms having selected this end as the most
convenient for the purpose, but from having
first tried in other ways and failed. This no-
tion was countenanced by the manner in which
worms in confinement were seen to drag about
and drop the triangles; but then they were
working carelessly. I did not at first perceive
the importance of this subject, but merely no-
ticed that the bases of those triangles which
7

90

HABITS OF WORMS.

Chap. II.

had been drawn in by the apex, were generally
clean and not crumpled. The subject was
afterwards attended to carefully. In the first
place several triangles which had been drawn
in by the basal angles, or by the base, or a
little above the base, and which were thus
much crumpled and dirtied, were left for some
hours in water and were then well shaken
while immersed; but neither the dirt nor the
creases were thus removed. Only slight
creases could be obliterated, even by pulling
the wet triangles several times through my
fingers. Owing to the slime from the worms’
bodies, the dirt was not easily washed off. We
may therefore conclude that if a triangle, be-
fore being dragged in by the apex, had been
dragged into a burrow by its base with even
a slight degree of force, the basal part would
long retain its creases and remain dirty. The
condition of 89 triangles (65 narrow and 24
broad ones), which had been drawn in by the
apex, was observed; and the bases of only 7
of them were at all creased, being at the same
time generally dirty. Of the 82 uncreased tri-
angles, 14 were dirty at the base; but it does

THEIR INTELLIGENCE.

Chap. II.

9*

not follow from this fact that these had first
been dragged towards the burrows by their
bases; for the worms sometimes covered large
portions of the triangles with slime, and these
when dragged by the apex over the ground
would be dirtied; and during rainy weather,
the triangles were often dirtied over one whole
side or over both sides. If the worms had
dragged the triangles to the mouths of their
burrows by their bases, as often as by their
apices, and had then perceived, without actual-
ly trying to draw them into the burrow, that
the broader end was not well adapted for this
purpose — even in this case a large proportion
would probably have had their basal ends dir-
tied. We may therefore infer — improbable as
is the inference — that worms are able by some
means to judge which is the best end by which
to draw triangles of paper into their bur-
rows.

The percentage results of the foregoing ob-
servations on the manner in which worms
draw various kinds of objects into the mouths
of their burrows may be abridged as fol-
lows : — -

92

HABITS OF WORMS.

Chap. II.

Nature of Object.

Drawn
into the
bur-
rows, by
or near
the

Drawn
in, by or
near the
middle.

Drawn
in, by or
near the
base.

apex.

Leaves of various kinds

8o

II

9

of the Lime, basal margin of blade

broad, apex acuminated .

79

17

4

— of a Laburnum, basal part of blade

as narrow as, or sometimes lit-
tle narrower than the apical
part .

63

10

27

of the Rhododendron, basal part

of blade often narrower than
the apical part

34

66

of Pine-trees, consisting of two

needles arising from a common
base .

100

Petioles of a Clematis, somewhat pointed
at the apex, and blunt at the
base .

76

24

of the Ash, the thick basal end

often drawn in to serve as food

48.5

51.5

of Robinia, extremely thin, espe-

dally towards the apex, so as
to be ill-fitted for plugging up
the burrows ....

44

56

Triangles of paper, of the two sizes

62

15

23

of the broad ones alone .

59

25

16

of the narrow ones alone

65

14

21

If we consider these several cases, we can
hardly escape from the conclusion that worms
show some degree of intelligence in their man-
ner of plugging up their burrows. Each par-
ticular object is seized in too uniform a man-

1

Chap. II.

THEIR INTELLIGENCE.

93

ner, and from causes which we can generally
understand, for the result to be attributed to
mere chance. That every object has not been
drawn in by its pointed end, may be accounted
for by labour having been saved through some
being inserted by their broader or thicker ends.
No doubt Xvorms are led by instinct to plug
up their burrows; and it might have been ex-
pected that they would have been led by in-
stinct how best to act in each particular case,
independently of intelligence. We see how
difficult it is to judge whether intelligence
comes into play, for even plants might some-
times be thought to be thus directed; for in-
stance when displaced leaves re-direct their
upper surfaces towards the light by extremely
complicated movements and by the shortest
course. With animals, actions appearing due
to intelligence may be performed through in-
herited habit without any intelligence, al-
though aboriginally thus acquired. Or the
habit may have been acquired through the
preservation and inheritance of beneficial vari-
ations of some other habit; and in this case
the new habit will have been acquired inde-

94

HABITS OF WORMS.

Chap. II.

pendently of intelligence throughout the whole
course of its development. There is no a priori
improbability in worms having acquired spe-
cial instincts through either of these two latter
means. Nevertheless it is incredible that in-
stincts should hqve been developed in refer-
ence to objects/such as the leaves or petioles
of foreign plahts, wholly unknown to the pro-
genitors oj/the worms which act in the de-
scribed manner. Nor are their actions so un-
varying or inevitable as are most true in-
stincts.

As worms are not guided by special in-
stincts in each particular case, though possess-
ing a general instinct to plug up their bur-
rows, and as chance is excluded, the next most
probable conclusion seems to be that they try
in many different ways to draw in objects, and
at last succeed in some one way. But it is sur-
prising that an animal so low in the scale as a
worm should have the capacity for acting in
this manner, as many higher animals have no
such capacity. For instance, ants may be
seen vainly trying to drag an object transverse-
ly to their course, which could be easily drawn

Chap. II.

THEIR INTELLIGENCE.

95

longitudinally; though after a time they gen-
erally act in a wiser manner. M. Fabre states *
that a Sphex — an insect belonging to the same
highly-endowed order with ants — stocks its
nest with paralysed grasshoppers, which are
invariably dragged into the burrow by their
antennae. When these were cut off close to
the head, the Sphex seized the palpi; but when
these were likewise cut off, the attempt to drag
its prey into the burrow was given up in de-
spair. The Sphex had not intelligence enough
to seize one of the six legs or the ovipositor of
the grasshopper, which, as M. Fabre remarks,
would have served equally well. So again, if
the paralysed prey with an egg attached to it
be taken out of the cell, the Sphex after enter-
ing and finding the cell empty, nevertheless
closes it up in the usual elaborate manner.
Bees will try to escape and go on buzzing for
hours on a window, one half of which has been
left open. Even a pike continued during three
months to dash and bruise itself against the
glass sides of an aquarium, in the vain attempt

* See his interesting work, “ Souvenirs entomologiques,”
1879, pp. 168-177.

g6 HABITS OF WORMS. Chap. IL

to seize minnows on the opposite side.* A
cobra-snake was seen by Mr. Layard j- to act
much more wisely than either the pike or the
Sphex; it had swallowed a toad lying within
a hole, and could not withdraw its head; the
toad was disgorged, and began to crawl away;
it was again swallowed and again disgorged;
and now the snake had learnt by experience,
for it seized the toad by one of its legs and
drew it out of the hole. The instincts of even
the higher animals are often followed in a
senseless or purposeless manner: the weaver-
bird will perseveringly wind threads through
the bars of its cage, as if building a nest: a
squirrel will pat nuts on a wooden floor, as if
he had just buried them in the ground: a
beaver will cut up logs of wood and drag them
about, though there is no water to dam up;
and so in many other cases.

Mr. Romanes, who has specially studied
the minds of animals, believes that we can
safely infer intelligence, -orriy-wfaTr-we^see an

* Mobius, “ Die Bewegungen der Thiere,” &c., 1873, p.
in.

f ‘‘Annals and Mag. of N. History,” series ii. vol. ix. 1852,
P- 333.

Chap. II.

THEIR INTELLIGENCE.

97

By this test the cobra showed some intelli-
gence; but this would have been much plainer
if on a second occasion he had drawn a toad
out of a hole by its leg. The Sphex failed sig-
nally in this respect. Now if worms try to
drag objects into their burrows first in one
way and then in another, until they at last suc-
ceed, they profit, at least in each particular
instance, by experience.

But evidence has been advanced showing
that worms do not habitually try to draw
objects into their burrows in many different
ways. Thus half-decayed lime-leaves from
their flexibility could have been drawn in by
their middle or basal parts, and were thus
drawn into the burrows in considerable num-
bers; yet a large majority were drawn in by
or near the apex. The petioles of the Clematis
could certainly have been drawn in with equal
ease by the base and apex; yet three times
and in certain cases five times as many were
drawn in by the a^x as by the base. It might
have been thought that the foot-stalks of
leaves would have tempted the worms as a con-

98

HABITS OF WORMS.

Chap. II.

venient handle; yet they are not largely used,
except when the base of the blade is narrower
than the apex. A large number of the petioles
of the ash are drawn in by the" base; but this
part serves the worms as food. In the case of
pine-leaves worms plainly show that they at
least do not seize the leaf by chance; but their
choice does not appear to be determined by
the divergence of the two needles, and the
consequent advantage or necessity of drawing
them into their burrows by the base. With
respect to the triangles of paper, those which
had been drawn in by the apex rarely had
their bases creased or dirty; and this shows
that the worms had not often first tried to
drag them in by this end.

If worms are able to judge, either before
drawing or after having drawn an object close
to the mouths of their burrows, how best to
drag it in, they must acquire some notion of
its general shape. This they probably acquire
by touching it in many places with the an-
terior extremity of their bodies, which serves
as a tactile organ. It may be well to remem-
ber how perfect the sense of touch becomes

Chap. II.

THEIR INTELLIGENCE.

99

in a man when born blind and deaf, as are
worms. If worms have the power of acquiring
some notion, however rude, of the shape of an
object and of their burrows, as seems to be
the case, they deserve to be called intelligent;
for they then act in nearly the same manner as
would a man under similar circumstances. J
To sum up, as chance does not determine
the manner in which objects are drawn into
the burrows, and as the existence of special-
ized instincts for each particular case cannot
be admitted, the first and most natural sup-
position is that worms try all methods until
they at last succeed; but many appearances
are opposed to such a supposition. One al-
ternative alone is left, namely, that worms,
although standing low in tbe scale of organiza-
tion, possess some degree of intelligence. This
will strike every one as very improbable; but
it may be doubted whether we know enough
about the nervous system of the lower animals
to justify our natural distrust of such a con-
clusion. With respect to the small size of the
cerebral ganglia, we should remember what
a mass of inherited knowledge, with some

IOO

HABITS OF WORMS.

Chap. II.

power of adapting means to an end, is crowded
into the minute brain of a worker-ant.

Means by which worms excavate their bur-
rows.— This is effected in two ways; by push-
ing away the earth on all sides, and by^swalc
lov^gjt^ In tK~e tormer caseT~the worm inserts
the stretched out and attenuated anterior ex-
tremity of its body into any little crevice, or
hole ; and then, as Perrier remarks,* the
pharynx is pushed forwards into this part,
which consequently swells and pushes away
the earth on all sides. The anterior extremity
thus serves as a wedge. It also serves, as we
have before seen, for prehension and suction,
and as a tactile organ. A worm was placed on
loose mould, and it buried itself in between
two and three minutes. On another occasion
four worms disappeared in 1 5 minutes between
the sides of the pot and the earth, which had
been moderately pressed down. On a third
occasion three large worms and a small one
were placed on loose mould well mixed with
fine sand and firmly pressed down, and they
all disappeared, except the tail of one, in 35

* “ Archives de Zoolog. exper.,” tom. iii. 1874, p. 405.

Chap. II. EXCAVATION OF THEIR BURROWS, iqi

minutes. On a fourth occasion six large
worms were placed on argillaceous mud mixed
with sand firmly pressed down, and they dis-
appeared, except the extreme tips of the tails
of two of them, in 40 minutes. In none of
these cases, did the worms swallow, as far as
could be seen, any earth. They generally en-
tered the ground close to the sides of the pot.

A pot was next filled with very fine ferru-
ginous sand, which was pressed down, well
watered, and thus rendered extremely com-
pact. A large worm left on the surface did
not succeed in penetrating it for some hours,
and did not bury itself completely until 25
hrs. 40 min. had elapsed. This was effected
by the sand being swallowed, as was evident
by the large quantity ejected from the vent,
long before the whole body had disappeared.
Castings of a similar nature continued to be
ejected from the burrow during the whole of
the following day.

As doubts have been expressed by some
writers whether worms ever swallow earth
solely for the sake of making their burrows,
some additional cases may be given. A mass

102

HABITS OF WORMS.

Chap. II.

of fine reddish sand, 23 inches in thickness,
left on the ground for nearly two years, had
been penetrated in many places by worms;
and their castings consisted partly of the red-
dish sand and partly of black earth brought up
from beneath the mass. This sand had been
dug up from a considerable depth, and was
of so poor a nature that weeds could not grow
on it. It is therefore highly improbable that
it should have been swallowed by the worms
as food. Again in a field near my house the
castings frequently consist of almost pure
chalk, which lies at only a little depth beneath
the surface; and here again it is very improb-
able that the chalk should have been swallowed
for the sake of the very little organic matter
which could have percolated into it from the
poor overlying pasture. Lastly, a casting
thrown up through the concrete and decayed
mortar between the tiles, with which the now
ruined aisle of Beaulieu Abbey had formerly
been paved, was washed, so that the coarser
matter- alone was left. This consisted of grains
of quartz, micaceous slate, other rocks, and.
bricks or tiles, many of them from to ^

Chap. II. EARTH SWALLOWED AS FOOD.

103

inch in diameter. No one will suppose that
these grains were swallowed as food, yet they
formed more than half of the casting, for they
weighed 19 grains, the whole casting having
weighed 33 grains. Whenever a worm bur-
rows to a depth of some feet in undisturbed
compact ground, it must form its passage by
swallowing the earth; for it is incredible that
the ground could yield on all sides to the pres-
sure of the pharynx when pushed forwards
within the worm’s body.

That worms swallow a larger quantity of
earth for the sake of extracting any nutritious
matter which it may contain than for making
their burrows, appears to me certain. But
as this old belief has been doubted by so high
an authority as Claparede, evidence in its
favour must be given in some detail. There
is no a priori improbability in such a belief,
for besides other annelids, especially the Areni-
cola marina , which throws up such a profusion
of castings on our tidal sands, and which it is
believed thus subsists, there are animals be-
longing to the most distinct classes, which do
not burrow, but habitually swallow large

104

HABITS OF WORMS.

Chap. II.

quantities of sand; namely the molluscan On-
chidium and many Echinoderms.*

If earth were swallowed only when worms
deepened their burrows or made new ones,
castings would be thrown up only occasion-
ally; but in many places fresh castings may
be seen every morning, and the amount of
earth ejected from the same burrow on suc-
cessive days is large. Yet worms do not bur-
row to a great depth, except when the weath-
er is very dry or intensely cold. On my lawn
the black vegetable mould is only about 5
inches in thickness, and overlies light-coloured
or reddish clayey soil: now when castings are
thrown up in the greatest profusion, only a
small proportion are light coloured, and it is
incredible th^dy^wcHmrs-Ahmdd^TLail^ make
fresh burrows in every direction in the thin
superficial layer of dark-coloured humus, un-
less they obtained fflitriment of some kindfrOMi

it I have obseWed a strictly analogous case

in a field near my house where bright red clay
lay close beneath the surface. Again on one

* I state this on the authority of Semper, “ Reisen im Archi-
pel der Philippinen,” Th. ii. 1877, p. 30.

Chap. II. EARTH SWALLOWED AS FOOD.

105

part of the Downs near Winchester the vege-
table mould overlying the chalk was found to
be only from 3 to 4 inches in thickness; and
the many castings here ejected were as black
as ink and did not effervesce with acids; so
that the worms must have confined themselves
to this thin superficial layer of mould, of which
large quantities were daily swallowed. In an-
other place at no great distance the castings
were white; and why the worms should have
burrowed into the chalk in some places and
not in others, I am unable to conjecture.

Two great piles of leaves had been left to
decay in my grounds, and months after their
removal, the bare surface, several yards in
diameter, was so thickly covered during sev-
eral months with castings that they formed an
almost continuous layer; and the large num-
ber of worms which lived here must have sub-
sisted during these months on nutritious mat-
ter contained in the black earth.

The lowest layer from another pile of de-
cayed leaves mixed with some earth was ex-
amined under a high power, and the number

of spores of various shapes and sizes which

8

io6

HABITS OF WORMS.

Chap. II.

it contained was astonishingly great; and these
crushed in the gizzards of worms may largely
aid in supporting them. Whenever castings
are thrown up in the greatest number, few or
no leaves are drawn into the burrows; for in-
stance the turf along a hedge-row, about 200
yards in length, was daily observed in the au-
tumn during several weeks, and every morn-
ing many fresh castings were seen; but not a
single leaf was drawn into these burrows.
These castings from their blackness and from
the nature of the subsoil could not have been
brought up from a greater depth than 6 or 8
inches. On what could these worms have sub-
sisted during this whole time, if not on matter
contained in the black earth? On the other
hand, whenever a large number of leaves are
drawn into the burrows, the worms seem to
subsist chiefly on them, for few earth-castings
are then ejected on the surface. This differ-
ence in the behaviour of worms at different
times, perhaps explains a statement by Clapa-
rede, namely, that triturated leaves and earth
are always found in distinct parts of their in-
testines.

Chap. II. EARTH SWALLOWED AS FOOD.

107

Worms sometimes abound in places where
they can rarely or never obtain dead or living
leaves; for instance, beneath the pavement in
well-swept courtyards, into which leaves are
only occasionally blown. My son Horace ex-
amined a house, one corner of which had sub-
sided; and he found here in the cellar, which
was extremely damp, many small worm-cast-
ings thrown up between the stones with which
the cellar was paved; and in this case it is im-
probable that the worms could ever have ob-
tained leaves.

But the best evidence, known to me, of
worms subsisting for at least considerable pe-
riods of time solely on the organic matter con^
tained in earth, is afforded by some facts com-
municated to me by Dr. King. Near Nice
large castings abound in extraordinary num-
bers, so that 5 or 6 were often found within
the space of a square foot. They consist of
fine, pale-coloured earth, containing calcare-
ous matter, which after having passed through
the bodies of worms and being dried, coheres
with considerable force. I have reason to be-
lieve that these castings had been formed by

io8

HABITS OF WORMS.

Chap. II.

species of Perichseta, which have been natural-
ised here from the East.* They rise like tow-
ers (see Fig. 2), with their summits often a little
broader than their bases, sometimes to a height
of above 3 and often to a height of 2% inches.
The tallest of those which were measured was
3.3 inches in height and 1 in diameter. A
small cylindrical passage runs up the centre of
each tower, through which the worm ascends
to eject the earth which it has swallowed, and
thus to add to its height. A structure of this
kind would not allow leaves being easily
dragged from the surrounding ground into the
burrows; and Dr. King, who looked carefully,
never saw even a fragment of a leaf thus drawn
in. Nor could any trace be discovered of the

* Dr. King gave me some worms collected near Nice, which,
as he believes, had constructed these castings. They were sent
to M. Perrier, who with great kindness examined and named them
for me : they consisted of Perichceta affinisy a native of Cochin
China and of the Philippines ; P. Luzonica , a native of Luzon
in the Philippines ; and P. Houlleti , which lives near Calcutta.
M. Perrier informs me that species of Perichaeta have been
naturalized in the gardens near Montpellier and in Algiers.
Before I had any reason to suspect that the tower-like castings
from Nice had been formed by worms not endemic in the coun-
try, I was greatly surprised to see how closely they resembled
castings sent to me from near Calcutta, where it is known that
species of Perichaeta abound.

Chap. II. EARTH SWALLOWED AS FOOD. 109

worms having crawled down the exterior sur-
faces of the towers in search of leaves; and had
they done so, tracks would almost certainly

Fig. 2. — Tower-like casting from near Nice, constructed of
earth, voided probably by a species of Perichaeta ; of natu-
ral size, copied from a photograph.

have been left on the upper part whilst it re-
mained soft. It does not, however, follow
that these worms do not draw leaves into their
burrows during some other season of the year,

I IO

HABITS OF WORMS.

Chap. II.

at which time they would not build up their
towers.

From the several foregong cases, it a
hardly be doubted that worms swallow eart

not only for the sake of making their burrow
but for obtaining food. Hensen, however,
concludes from his analyses of humus that
worms probably could not live on ordinary
vegetable mould, though he admits that they
might be nourished to some extent by leaf-
mould.* But we have seen that worms eager-
ly devour raw meat, fat, and dead worms; and
ordinary mould can hardly fail to obtain many
ova, larvae, and small living or dead creatures,
spores of cryptogamic plants, and micrococci,
such as those which give rise to saltpetre.
These various organisms, together with some
cellulose from any leaves and roots not utterly
decayed, might well account for such large
quantities of mould being swallowed by
worms. It may be worth while here to recall
the fact that certain species of Utricularia,
which grow in damp places in the tropics, pos-

* “ Zeitschrift fur wissenschaft. Zoolog.,” B. xxviii, 1877,

p. 364.

Chap. II. DEPTH OF THEIR BURROWS.

Ill

sess bladders beautifully constructed for catch-
ing minute subterranean animals; and these
traps would not have been developed unless
many small animals inhabited such soil.

The depth to which worms penetrate, and the
construction of their burrows . — Although worms
usually live near the surface, yet they burrow
to a considerable depth during long-continued
dry weather and severe cold. In Scandinavia,
according to Eisen, and in Scotland, according
to Mr. Lindsay Carnagie, the burrows run
down to a depth of from 7 to 8 feet; in North
Germany, according to Hoffmeister, from 6 to
8 feet, but Hensen says, from 3 to 6 feet. This
latter observer has seen worms frozen at a
depth of 1^ feet beneath the surface. I have
not myself had many opportunities for obser-
vation, but I have often met with worms at
depths of 3 to 4 feet. In a bed of fine sand
overlying the chalk, which had never been dis-
turbed, a worm was cut into two at 55 inches,
and another was found here in December at
the bottom of its burrow, at 61 inches beneath
the surface. Lastly, in earth near an old Ro-
man Villa, which had not been disturbed for

1 12

HABITS OF WORMS.

Chap. II.

many centuries, a worm was met with at a
depth of 66 inches; and this was in the middle
of August.

The burrows run down perpendicularly, or
more commonly a little obliquely. They are
said sometimes to branch, but as far as I have
seen this does not occur, except in recently
dug ground and near the surface. They are
generally, or as I believe invariably, lined with
a thin layer of fine, dark-coloured earth voided
by the worms; so that they must at first be
made a little wider than their ultimate diame-
ter. I have seen several burrows in undis-
turbed sand thus lined at a depth of 4 ft. 6 in.;
and others close to the surface thus lined
in recently dug ground. The walls of fresh
burrows are often dotted with little globular
pellets of voided earth, still soft and viscid;
and these, as it appears, are spread out on all
sides by the worm as it travels up or down its
burrow. The lining thus formed becomes
very compact and smooth when nearly dry,
and closely fits the worm’s body. The minute
reflexed bristles which project in rows on all
sides from the body, thus have excellent points

Ch. II. CONSTRUCTION OF THEIR BURROWS. 113

of support; and the burrow is rendered well
adapted for the rapid movement of the animal.
The lining appears also to strengthen the
walls, and perhaps saves the worm's body from
being scratched. I think so because several
burrows which passed through a layer of sifted
coal-cinders, spread over turf to a thickness
of 1^ inch, had been thus lined to an unusual
thickness. In this case the worms, judging
from the castings, had pushed the cinders
away on all sides and had not swallowed any of
them. In another place, burrows similarly
lined, passed through a layer of coarse coal-
cinders, 3^ inches in thickness. We thus see
that the burrows are not mere excavations,
but may rather be compared with tunnels lined
with cement.

The mouths of the burrow are in addition
often lined with leaves; and this is an instinct
distinct from that of plugging them up, and
does not appear to have been hitherto no-
ticed. Many leaves of the Scotch-fir or pine
{Finns sylvestris) were given to worms kept in
confinement in two pots; and when after sev-
eral weeks the earth was carefully broken up,

1 14 HABITS OF WORMS. Chap. II.

the upper parts of three oblique burrows were
found surrounded for lengths of 7, 4, and 3^
inches with pine-leaves, together with frag-
ments of other leaves which had been given the
worms as food. Glass beads and bits of tile,
which had been strewed on the surface of the
soil, were stuck into the interstices between
the pine-leaves; and these interstices were
likewise plastered with the viscid castings void-
ed by the worms. The structures thus formed
cohered so well, that I succeeded in removing
one with only a little earth adhering to it. It
consisted of a slightly curved cylindrical case,
the interior of which could be seen through
holes in the sides and at either end. The pine-
leaves had all been drawn in by their bases;
and the sharp points of the needles had been
pressed into the lining of voided earth. Had
this not been effectually done, the sharp points
would have prevented the retreat of the worms
into their burrows; and these structures would
have resembled traps armed with converging
points of wire, rendering the ingress of an ani-
mal easy and its egress difficult or impossible.
The skill shown by these worms is noteworthy

Ch.IL CONSTRUCTION OF THEIR BURROWS. 1 15

and is the more remarkable, as the Scotch pine
is not a native of this district.

After having examined these burrows made
by worms in confinement, I looked at those in
a flower-bed near some Scotch pines. These
had all been plugged up in the ordinary man-
ner with the leaves of this tree, drawn in for a
length of from 1 to 1^ inch; but the mouths of
many of them were likewise lined with them,
mingled with fragments of other kinds of
leaves, drawn in to a depth of 4 or 5 inches.
Worms often remain, as formerly stated, for
a long time close to the mouths of their bur-
rows, apparently for warmth; and the basket-
like structures formed of leaves would keep
their bodies from coming into close contact
with the cold damp earth. That they habitu-
ally rested on the pine-leaves, was rendered
probable by their clean and almost polished
surfaces.

The burrows which run far down into the
ground, generally, or at least often, terminate
in a little enlargement or chamber. Here, ac-
cording to Hoffmeister, one of several worms
pass the winter rolled up into a ball. Mr. Lind-

n6

HABITS OF WORMS.

Chap. II.

say Carnagie informed me (1838) that he had
examined many burrows over a stone-quarry
in Scotland, where the overlying boulder-clav
and mould had recently been cleared away,
and a little vertical cliff thus left. In several
cases the same burrow was a little enlarged at
two or three points one beneath the other;
and all the burrows terminated in a rather
large chamber, at a depth of 7 or 8 feet from
the surface. These chambers contained many
small sharp bits of stone and husks of flax-
seeds. They must also have contained living
seeds, for on the following spring Mr. Carnagie
saw grass-plants sprouting out of some of the
intersected chambers. I found at Abinger in
Surrey two burrows terminating in similar
chambers at a depth of 36 and 41 inches, and
these were lined or paved with little pebbles,
about as large as mustard seeds; and in one of
the chambers there was a decayed oat-grain,
with its husk. Hensen likewise states that
the bottoms of the burrows are lined with little
stones; and where these could not be procured,
seeds, apparently of the pear, had been used,
as many as fifteen having been carried down

Ch. II. CONSTRUCTION OF THEIR BURROWS. 117

into a single burrow, one of which had ger-
minated.* We thus see how easily a botanist
might be deceived who wished to learn how
long deeply buried seeds remained alive, if he
were to collect earth from a considerable depth,
on the supposition that it could contain only
seeds which had long lain buried. It is proba-
ble that the little stones, as well as the seeds,
are carried down from the surface by being
swallowed; for a surprising number of glass
beads, bits of tile and of glass were certainly
thus carried down by worms kept in pots; but
some may have been carried down within their
mouths. The sole conjecture which I can
form why worms line their winter quarters
with little stones and seeds, is to prevent their
closely coiled-up bodies from coming into close
contact with the surrounding cold soil; and
such contact would perhaps interfere with
their respiration which is effected by the skin
alone.

A worm after swallowing earth, whether
for making its burrow or for food, soon comes

* “ Zeitschrift fur wissenschaft. Zoolog.,” B. xxviii. 1877, p.

356.

1 1 8

HABITS OF WORMS.

Chap. II.

to the surface to empty its body. The ejected
earth is thoroughly mingled with the intestinal
secretions, and is thus rendered viscid. After
being dried it sets hard. I have watched
worms during the act of ejection, and when
the earth was in a very liquid state it was eject-
ed in little spurts, and when not so liquid by a
slow peristaltic movement. It is not cast in-
differently on any side, but with some care,
first on one and then on another side; the tail
being used almost like a trowel. As soon as a
little heap is formed, the worm apparently
avoids, for the sake of safety, protruding its
tail; and the earthy matter is forced up
through the previously deposited soft mass.
The mouth of the same burrow is used for this
purpose for a considerable time. In the case
of the tower-like castings (see Fig. 2) near
Nice, and of the similar but still taller towers
from Bengal (hereafter to be described and
figured) a considerable degree of skill is exhib-
ited in their construction. Dr. King also ob-
served that the passage up these towers hardly
ever ran in the same exact line with the under-
lying burrow, so that a thin cylindrical object

Chap.II. EJECTION OF THEIR CASTINGS. i jg

such as a haulm of grass, could not be passed
down the tower into the burrow; and this
change of direction probably serves in some
manner as a protection. When a worm comes
to the surface to eject earth, the tail pro-
trudes, but when it collects leaves its head
must protrude. Worms therefore must have
the power of turning round in their closely-
fitting burrows; and this, as it appears to us,
would be a difficult feat.

Worms do not always eject their castings
on the surface of the ground. When they can
find any cavity, as when burrowing in newly
turned-up earth, or between the stems of
banked-up plants, they deposit their castings
in such places. So again any hollow beneath
a large stone lying on the surface of the
ground, is soon filled up with their castings.
According to Hensen, old burrows are habitu-
ally used for this purpose; but as far as my ex-
perience serves, this is not the case, excepting
with those near the surface in recently dug
ground. I think that Hensen may have been
deceived by the walls of old burrows, lined
with black earth, having sunk in or collapsed;

120

HABITS OF WORMS.

Chap. II.

for black streaks are thus left, and these are
conspicuous when passing through light-col-
oured soil, and might be mistaken for corh-
pletely filled-up burrows.

It is certain that old burrows collapse in
the course of time; for as we shall see in the
next chapter, the fine earth voided by worms,
if spread out uniformly, would form in many
places in the course of a year a layer £ of an
inch in thickness; so that at any rate this large
amount is not deposited within the old unused
burrows. If the burrows did not collapse, the
whole ground would be first thickly riddled
with holes to a depth of about ten inches, and
in fifty years a hollow unsupported space, ten
inches in depth, would be left. The holes left
by the decay of successively formed roots of
trees and plants must likewise collapse in the
course of time.

The burrows of worms run down perpen-
dicularly or a little obliquely, and where the
soil is at all argillaceous, there is no difficulty
in believing that the walls would slowly flow
or slide inwards during very wet weather.
When, however, the soil is sandy or mingled

Chap. II. THE COLLAPSE OF OLD BURROWS. I2l

with many small stones, it can hardly be vis-
cous enough to flow inwards during even the
wettest weather; but another agency may here
come into play. After much rain the ground
swells, and as it cannot expand laterally, the
surface rises; during dry weather it sinks
again. For instance, a large flat stone laid’ on
the surface of a field sank 3.33 mm. whilst the
weather was dry between May 9th and June
13th, and rose 1.91 mm. between September
7th and 19th, much rain having fallen during
the latter part of this time. During frosts and
thaws the movements were twice as great.
These observations were made by my son Hor-
ace, who will hereafter publish an account of
the movements of this stone during successive
wet and dry seasons, and of the effects of its
being undermined by worms. Now when the
ground swells, if it be penetrated by cylindrical
holes, such as worm-burrows, their walls will
tend to yield and be pressed inwards; and the
yielding will be greater in the deeper parts
(supposing the whole to be equally moistened)
from the greater weight of the superincum-
bent soil which has to be raised, than in the
9

122

HABITS OF WORMS.

Chap. II.

parts near the surface. When the ground
dries, the walls will shrink a little and the bur-
rows will be a little enlarged. Their enlarge-
ment, however, through the lateral contrac-
tion of the ground, will not be favoured, but
rather opposed, by the weight of the superin-
cumbent soil.

Distribution of Worms. — Earth-worms are
found in all parts of the world, and some of
the genera have an enormous range.* They
inhabit the most isolated islands; they abound
in Iceland, and are known to exist in the West
Indies, St. Helena, Madagascar, New Cale-
donia and Tahiti. In the Antarctic regions,
worms from Kerguelen Land have been de-
scribed by Ray Lankester; and I found them
in the Falkland Islands. How they reach such
isolated islands is at present quite unknown.
They are easily killed by salt-water, and it does
not appear probable that young worms or their
egg-capsules could be carried in earth adhering
to the feet or beaks of land-birds. Moreover
Kerguelen Land is not now inhabited by any
land-bird.

* Perrier, “ Archives de Zoolog. exper.,” tom. 3, p. 378, 1874.

Chap. II. THEIR WIDE DISTRIBUTION. 123

In this volume we are chiefly concerned
with the earth cast up by worms, and I have
gleaned a few facts on this subject with re-
spect to distant lands. Worms throw up
plenty of castings in the United States. In
Venezuela, castings, probably ejected by spe-
cies of Urochseta, are common in the gardens
and fields, but not in the forests, as I hear from
Dr. Ernst of Caracas. He collected 156 cast-
ings from the court-yard of his house, having
an area of 200 square yards. They varied in
bulk from half a cubic centimetre to five cubic
centimetres, and were on an average three cu-
bic centimetres. They were, therefore, of
small size in comparison with those often
found in England; for six large castings from
a field near my house averaged 16 cubic centi-
metres. Several species of earth-worms are
common in St. Catharina in South Brazil, and
Fritz Muller informs me “ that in most parts
of the forests and pasture-lands, the whole soil,
to a depth of a quarter of a metre, looks as if it
had passed repeatedly through the intestines
of earth-worms, even where hardly any cast-
ings are to be seen on the surface.” A gigan-

124 HABITS OF WORMS. Chap. II.

tic but very rare species is found there, the
burrows of which are sometimes even two cen-
timetres or nearly f of an inch in diameter,
and which apparently penetrate the ground to
a great depth.

In the dry climate of New South Wales, I
hardly expected that worms would be com-
mon; but Dr. G. Krefft of Sydney, to whom
I applied, after making inquiries from gar-
deners and others, and from his own observa-
tions, informs me that their castings abound.
He sent me some collected after heavy rain,
and they consisted of little pellets, about .15
inch in diameter; and the blackened sandy
earth of which they were formed still cohered
with considerable tenacity.

The late Mr. John Scott of the Botanic
Gardens near Calcutta made many observa-
tions for me on worms living under the hot
and humid climate of Bengal. The castings
abound almost everywhere, in jungles and in
the open ground, to a greater degree, as he
thinks, than in England. After the water has
subsided from the flooded rice-fields, the whole
surface very soon becomes studded with cast-

Chap. II. THEIR WIDE DISTRIBUTION.

125

ings — a fact which much surprised Mr. Scott,
as he did not know how long worms could
survive beneath water. They cause much
trouble in the Botanic garden, “ for some of
the finest of our lawns can be kept in any-
thing like order only by being almost daily
rolled; if left undisturbed for a few days they
become studded with large castings.” These
closely resemble those described as abounding
near Nice; and they are probably the work of
a species of Perichseta. They stand up like
towers, with an open passage in the centre.

A figure of one of these castings from a
photograph is here given (Fig. 3). The largest
received by me was 3^ inches in height and
1.35 inch in diameter; another was only f inch
in diameter and 2f in height. In the following
year, Mr. Scott measured several of the lar-
gest; one was 6 inches in height and nearly 1^
in diameter: two others were 5 inches in height
and respectively 2 and rather more than 2\
inches in diameter. The average weight of the
22 castings sent to me was 35 grammes (i j
oz.); and one of them weighed 44.8 grammes
(or 2 oz.). All these castings were thrown

126

HABITS OF WORMS.

Chap. II.

up either in one night or in two. Where the
ground in Bengal is dry, as under large trees,

Fig. 3. — A tower-like casting, probably ejected by a species of
Perichseta, from the Botanic Garden, Calcutta ; of natural
size, engraved from a photograph.

castings of a different kind are found in vast

Chap. II. THEIR WIDE DISTRIBUTION.

127

numbers; these consist of little oval or conical
bodies, from about the gV to rather above TV
of an inch in length. They are obviously void-
ed by a distinct species of worms.

The period during which worms near Cal-
cutta display such extraordinary activity lasts
for only a little over two months, namely, dur-
ing the cool season after the rains. At this
time they are generally found within about 10
inches beneath the surface. During the hot
season they burrow to a greater depth, and are
then found coiled up and apparently hybernat-
ing. Mr. Scott has never seen them at a
greater depth than 2\ feet, but has heard of
their having been found at 4 feet. Within the
forests, fresh castings may be found even dur-
ing the hot season. The worms in the Bo-
tanic garden, during the cool and dry season,
draw many leaves and little sticks into the
mouths of their burrows, like our English
worms; but they rarely act in this manner dur-
ing the rainy season.

Mr. Scott saw worm-castings on the lofty
mountains of Sikkim in North India. In
South India Dr. King found in one place, on

128

HABITS OF WORMS.

Chap. II.

the plateau of the Nilgiris, at an elevation of
7000 feet, “ a good many castings,” which are
interesting for their great size. The worms
which eject them are seen only during the wet
season, and are reported to be from 12 to 15

Fig. 4. — A casting from the Nilgiri Mountains in South India;
of natural size, engraved from a photograph.

inches in length, and as thick as a man’s little
finger. These castings were collected by Dr.
King after a period of no days without any
rain; and they must have been ejected either
during the north-east or more probably during

Chap.IL THEIR WIDE DISTRIBUTION. 129

the previous south-west monsoon; for their
surfaces had suffered some disintegration and
they were penetrated by many fine roots. A
drawing is here given (Fig. 4) of one which
seems to have best retained its original size
and appearance. Notwithstanding some loss
from disintegration, five of the largest of these
castings (after having been well sun-dried)
weighed each on an average 89.5 grammes, or
above 3 oz.; and the largest weighed 123.14
grammes, or 4^- oz., — that is above a quarter
of a pound! The largest convolutions were
rather more than one inch in diameter; but it
is probable that they had subsided a little
whilst soft, and that their diameters had thus
been increased. Some had flowed so much
that they now consisted of a pile of almost flat
confluent cakes. All were formed of fine,
rather light-coloured earth, and were surpris-
ingly hard and compact, owing no doubt to
the animal matter by which the particles of
earth had been cemented together. They did
not disintegrate, even when left for some
hours in water. Although they had been cast
up on the surface of gravelly soil, they con-

130

HABITS OF WORMS.

Chap. II.

tained extremely few bits of rock, the largest
of which was only .15 inch in diameter.

Dr. King saw in Ceylon a worm about 2
feet in length and \ inch in diameter; and he
was told that it was a very common species
during the wet season. These worms must
throw up castings at least as large as those on
the Nilgiri Mountains; but Dr. King saw
none during his short visit to Ceylon. Suffi-
cient facts have now been given, showing that
worms do much work in bringing up fine earth
to the surface in most or all parts of the world,
and under the most different climates.

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.

We now come to the more immediate sub-
ject of this volume, namely, the amount of
earth which is brought up by worms from be-
neath the surface, and is afterwards spread
out more or less completely by the rain and
wind. The amount can be judged of by two
methods, — by the rate at which objects left

on the surface are buried, and more accurately

131

132 AMOUNT OF EARTH Chap. III.

by weighing the quantity brought up within a
given time. We will begin with the first
method, as it was first followed.

Near Maer Hall in Staffordshire, quick-
lime had been spread about the year 1827
thickly over a field of good pasture-land, which
had not since been ploughed. Some square
holes were dug in this field in the beginning of
October, 1837; and the sections showed a layer
of turf formed by the matted roots of the
grasses, ^ inch in thickness, beneath which, at
a depth of 2\ inches (or 3 inches from the sur-
face), a layer of the lime in powder or in small
lumps could be distinctly seen running all
round the vertical sides of the holes. The
soil beneath the layer of lime was either gravel-
ly or of a coarse sandy nature, and differed con-
siderably in appearance from the overlying
dark-coloured fine mould. Coal-cinders had
been spread over a part of this same field either
in the year 1833 or 1834; and when the above
holes were dug, that is after an interval of 3
or 4 years, the cinders formed a line of black
spots round the holes, at a depth of 1 inch be-
neath the surface, parallel to and above the

Chap. III. BROUGHT UP BY WORMS. 133

white layer of lime. Over another part of this
field cinders had been strewed, only about half-
a-year before, and these either still lay on the
surface or were entangled among the roots
of the grasses; and I here saw the commence-
ment of the burying process, for worm-cast-
ings had been heaped on several of the smaller
fragments. After an interval of 4§ years this
field was re-examined, and now the two layers
of lime and cinders were found .almost every-
where at a greater depth than before by nearly
1 inch, we will say by § of an inch. Therefore
mould to an average thickness of .22 of an
inch had been annually brought up by the
worms, and had been spread over the surface
of this field.

Coal-cinders had been strewed over an-
other field, at a date which could not be posi-
tively ascertained, so thickly that they formed
(October, 1837) a layer, 1 inch in thickness at
a depth of about 3 inches from the surface.
The layer was so continuous that the overly-
ing dark vegetable mould was connected with
the sub-soil of red clay only by the roots of the
grasses; and when these were broken, the

134

AMOUNT OF EARTH

Chap. III.

mould and the red clay fell apart. In a third
field, on which coal-cinders and burnt marl
had been strewed several times at unknown
dates, holes were dug in 1842; and a layer of
cinders could be traced at a depth of 3^ inches,
beneath which at a depth of 9^ inches from
the surface there was a line of cinders together
with burnt marl. On the sides of one hole
there were two layers of cinders, at 2 and 3!
inches beneath the surface; and below them at
a depth in parts of 9^, and in other parts of
10J inches there were fragments of burnt marl.
In a fourth field two layers of lime, one above
the other, could be distinctly traced, and be-
neath them a layer of cinders and burnt marl
at a depth of from 10 to 12 inches below the
surface.

A piece of waste, swampy land was en-
closed, drained, ploughed, harrowed and thick-
ly covered in the year 1822 with burnt marl
and cinders. It was sowed with grass seeds,
and now supports a tolerably good but coarse
pasture. Holes were dug in this field in 1837,
or 15 years after its reclamation, and we see in
the accompanying diagram (Fig. 5), reduced

Chap. III. BROUGHT UP BY WORMS.

135

to half of the natural scale, that the turf was
inch thick, beneath which there was a layer of

Fig. 5. — Section, reduced to half the natural scale, of the vege-
table mould in a field, drained and reclaimed fifteen years
previously ; A, turf ; B, vegetable mould without any stones ;
C, mould with fragments of burnt marl, coal-cinders and
quartz pebbles ; D, sub-soil of black, peaty sand with quartz
pebbles.

vegetable mould 2^ inches thick. This layer
did not contain fragments of any kind; but be-

136 AMOUNT OF EARTH Chap. III.

neath it there was a layer of mould, 1^ inch
in thickness, full of fragments of burnt marl,
conspicuous from their red colour, one of
which near the bottom was an inch in length;
and other fragments of coal-cinders together
with a few white quartz pebbles. Beneath this
layer and at a depth of \\ inches from the sur-
face, the original black, peaty, sandy soil with
a few quartz pebbles was encountered. Here
therefore the fragments of burnt marl and cin-
ders had been covered in the course of 15 years
by a layer of fine vegetable mould, only 2\
inches in thickness, excluding the turf. Six
and a half years subsequently this field was re-
examined, and the fragments were now found
at from 4 to 5 inches beneath the surface. So
that in this interval of 6J years, about 1^ inch
of mould had been added to the superficial
layer. I am surprised that a greater quantity
had not been brought up during the whole 2i-§
years, for in the closely underlying black, peaty
soil there were many worms. It is, however,
probable that formerly, whilst the land re-
mained poor, worms were scanty; and the
mould would then have accumulated slowly.

Chap. III. BROUGHT UP BY WORMS. 137

The average annual increase of thickness for
the whole period is .19 of an inch.

Two other cases are worth recording. In
the spring of 1835, a field, which had long ex-
isted as poor pasture and was so swampy that
it trembled slightly when stamped on, was
thickly covered with red sand so that the
whole surface appeared at first bright red.
When holes were dug in this field after an in-
terval of about years, the sand formed a
layer at a depth of f in. beneath the surface.
In 1842 (i. e., 7 years after the sand had been
laid on) fresh holes were dug, and now the red
sand formed a distinct layer, 2 inches beneath
the surface, or 1^ inch beneath the turf; so
that on an average, .21 inches of mould had
been annually brought to the surface. Im-
mediately beneath the layer of red sand, the
original substratum of black sandy peat ex-
tended.

A grass field, likewise not far from Maer
Hall, had formerly been thickly covered with
marl, and was then left for several years as
pasture; it was afterwards ploughed. A

friend had three trenches dug in this field 28

10

138

AMOUNT OF EARTH

Chap. III.

years after the application of the marl,* and a
layer of the marl fragments could be traced at
a depth, carefully measured, of 12 inches in
some parts, and of 14 inches in other parts.
This difference in depth depended on the layer
being horizontal, whilst the surface consisted
of ridges and furrows from the field having
been ploughed. The tenant assured me that it
had never been turned up to a greater depth
than from 6 to 8 inches; and as the fragments
formed an unbroken horizontal layer from 12
to 14 inches beneath the surface, these must
have been buried by the worms whilst the land
was in pasture before it was ploughed, for
otherwise they would have been indiscrimi-
nately scattered by the plough throughout the
whole thickness of the soil. Four-and-a-half
years afterwards I had three holes dug in this
field, in which potatoes had been lately

* This case is given in a postscript to my paper in the
“ Transact. Geolog. Soc.” (vol. v. p. 505), and contains a serious
error, as in the account received I mistook the figure 30 for 80.
The tenant, moreover, formerly said that he had marled the field
thirty years before, but was now positive that this was done in
1809, that is twenty-eight years before the first examination of
the field by my friend. The error, as far as the figure 80 is
concerned, was corrected in an article by me, in the “ Gardeners’
Chronicle,” 1844, p. 218.

Chap. III. BROUGHT UP BY WORMS.

139

planted, and the layer of marl-fragments was
now found 13 inches beneath the bottoms of
the furrows, and therefore probably 15 inches
beneath the general level of the field. It
should, however, be observed that the thick-
ness of the blackish sandy soil, which had
been thrown up by the worms above the marl-
fragments in the course of 32^ years, would
have measured less than 1 5 inches, if the field
had always remained as pasture, for the soil
would in this case have been much more com-
pact. The fragments of marl almost rested
on an undisturbed sub-stratum of white sand
with quartz pebbles; and as this would be
little attractive to worms, the mould would
hereafter be very slowly increased by their
action.

We will now give some cases of the action
of worms, on land differing widely from the
dry sandy or the swampy pastures just de-
scribed. The chalk formation extends all
round my house in Kent; and its surface, from
having been exposed during an immense
period to the dissolving action of rain-water,
is extremely irregular, being abruptly fes-

140

AMOUNT OF EARTH

Chap. III.

tooned and penetrated by many deep well-like
cavities.* During the dissolution of the chalk,

* These pits or pipes are still in process of formation. During
the last forty years I have seen or heard of five cases, in which a
circular space, several feet in diameter, suddenly fell in, leaving
on the field an open hole with perpendicular sides, some feet in
depth. This occurred in one of my own fields, whilst it was
being rolled, and the hinder quarters of the shaft horse fell in ; two
or three cart-loads of rubbish were required to fill up the hole.
The subsidence occurred where there was a broad depression, as
if the surface had fallen in at several former periods. I heard
of a hole which must have been suddenly formed at the bottom
of a small shallow pool, where sheep had been washed during
many years, and into which a man thus occupied fell to his great
terror. The rain-water over this whole district sinks perpen-
dicularly into the ground, but the chalk is more porous in certain
places than in others. Thus the drainage from the overlying
clay is directed to certain points, where a greater amount of cal-
careous matter is dissolved than elsewhere. Even narrow open
channels are sometimes formed in the solid chalk. As the chalk
is slowly dissolved over the whole country, but more in some
parts than in others, the undissolved residue — that is, the over-
lying mass of red clay with flints — likewise sinks slowly down,
and tends to fill up the pipes or cavities. But the upper part
of the red clay holds together, aided probably by the roots of
plants, for a longer time than the lower parts, and thus forms
a roof, which sooner or later falls in, as in the above-mentioned
five cases. The downward movement of the clay may be com-
pared with that of a glacier, but is incomparably slower ; and this
movement accounts for a singular fact, namely that the much-
elongated flints which are embedded in the chalk in a nearly
horizontal position, are commonly found standing nearly or quite
upright in the red clay. This fact is so common that the work-
men assured me that this was their natural position. I roughly
measured one which stood vertically, and it was of the same
length and of the same relative thickness as one of my arms.

Chap. III. BROUGHT UP BY WORMS.

141

the insoluble matter, including a vast number
of unrolled flints of all sizes, has been left on
the surface and forms a bed of stiff red clay,
full of flints, and generally from 6 to 14 feet in
thickness. Over the red clay, wherever the
land has long remained as pasture, there is a
layer a few inches in thickness, of dark-col-
oured vegetable mould.

A quantity of broken chalk was spread,
on December 20, 1842, over a part of a field
near my house, which had existed as pasture
certainly for 30, probably for twice or thrice
as many years. The chalk was laid on the land
for the sake of observing at some future period
to what depth it would become buried. At
the end of Novemter, 1871, that is after an in-
terval of 29 years, a trench was dug across this
part of the field; and a line of white nodules

These elongated flints must get placed in their upright position,
on the same principle that a trunk of a tree left on a glacier
assumes a position parallel to the line of motion. The flints
in the clay which form almost half its bulk are very often
broken, though not rolled or abraded ; and this may be ac-
counted for by their mutual pressure, whilst the whole mass is
subsiding. I may add that the chalk here appears to have been
originally covered in parts by a thin bed of fine sand with some
perfectly rounded flint pebbles, probably of Tertiary age ; for such
sand often partly fills up the deeper pits or cavities in the chalk.

142

AMOUNT OF EARTH

Chap. III.

could be traced on both sides of the trench,
at a depth of 7 inches from the surface. The
mould, therefore (excluding the turf, had here
been thrown up at an average rate of .22 inches
per year. Beneath the line of 'chalk nodules
there was in parts hardly any fine earth free of
flints, while in other parts there was a layer,
2\ inches in thickness. In this latter case the
mould was altogether 9J inches thick; and in
one such spot a nodule of chalk and a smooth
flint pebble, both of which must have been left
at some former time on the surface, were found
at this depth. At from 1 1 to 12 inches beneath
the surface, the undisturbed reddish clay, full
of flints, extended. The appearance of the
above nodules of chalk surprised me much at
first, as they closely resembled water-worn
pebbles, whereas the freshly-broken fragments
had been angular. But on examining the
nodules with a lens, they no longer appeared
water-worn, for their surfaces were pitted
through unequal corrosion, and minute, sharp
points, formed of broken fossil shells, projected
from them. It was evident that the corners
of the original fragments of chalk had been

Chap. III. BROUGHT UP BY WORMS.

143

wholly dissolved, from presenting a large sur-
face to the carbonic acid dissolved in the rain-
water and to that generated in soil containing
vegetable matter, as well as to the humus-
acids.* The projecting corners would also,
relatively to the other parts, have been em-
braced by a larger number of living rootlets
and these have the power of even attacking
marble, as Sachs has shown. Thus, in the
course of 29 years, buried angular fragments
of chalk had been converted into well-rounded
nodules.

Another part of this same field was. mossy,
and as it was thought that sifted coal-cinders
would improve the pasture, a thick layer was
spread over this part either in 1842 or 1843
and another layer some years afterwards. In
1871 a trench was here dug, and many cinders
lay in a line a,t a depth of 7 inches beneath the
surface, with another line at a depth of 5^
inches parallel to the one beneath. In another
part of this field, which had formerly existed as
a separate one, and which it was believed had
been pasture-land for more than a century,

* S. W. Johnson, “ How Crops Feed,” 1870, p. 139.

144

AMOUNT OF EARTH

Chap. III.

trenches were dug to see how thick the veg-
etable mould was. By chance the first trench
was made at a spot where at some former
period, certainly more than forty years before,
a large hole had been filled up with coarse red
clay, flints, fragments of chalk, and gravel;
and here the fine vegetable mould was only
from 4^ to 4f inches in thickness. In an-
other and undisturbed place, the mould varied
much in thickness, namely from 6^ to 8^
inches; beneath which a few small fragments
of brick were found in one place. From these
several cases, it would appear that during the
last 29 years mould has been heaped on the
surface at an average annual rate of from .2
to .22 of an inch. But in this district when a
ploughed field is first laid down in grass, the
mould accumulates at a much slower rate.
The rate, also, must become very much slower
after a bed of mould, several inches in thick-
ness, has been formed; for the worms then
live chiefly near the surface, and burrow down
to a greater depth so as to bring up fresh earth
from below, only during the winter when the
weather is very cold (at which time worms

Chap. III. BROUGHT UP BY WORMS.

145

were found in this field at a depth of 26 inches)
and during summer, when the weather is very
dry.

A field, which adjoins the one just de-
scribed, slopes in one part rather steeply (viz.,
at from io° to 150); this part was last
ploughed in 1841, was then harrowed and left
to become pasture-land. For several years it
was clothed with an extremely scant vegeta-
tion, and was so thickly covered with small and
large flints (some of them half as large as a
child’s head) that the field was always called by
my sons “ the stony field. ” When they ran
down the slope the stones clattered together.
I remember doubting whether I should live to
see these larger flints covered with vegetable
mould and turf. But the smaller stones dis-
appeared before many years had elapsed, as did
every one of the larger ones after a time; so
that after thirty years (1871) a horse could gal-
lop over the compact turf from one end of the
field to the other, and not strike a single stone
with his shoes. To anyone who remembered
the appearance of the field in 1842, the trans-
formation was wonderful. This was certainly

X46 AMOUNT OF EARTH Chap. III.

the work of the worms, for though castings
were not frequent for several years, yet some
were thrown up month after month, and these
gradually increased in numbers as the pasture
improved. In the year 1871 a trench was dug
on the above slope, and the blades of grass
were cut off close to the roots, so that the
thickness of the turf and of the vegetable
mould could be measured accurately. The
turf was rather less than half an inch, and the
mould, which did not contain any stones, 2\
inches in thickness. Beneath this lay coarse
clayey earth full of flints, like that in any of
the neighbouring ploughed fields. This coarse
earth easily fell apart from the overlying mould
when a spit was lifted up. The average rate of
accumulation of the mould during the whole
thirty years was only .083 inch per year (i. e.,
nearly one inch in twelve years); but the rate
must have been much slower at first, and after-
wards considerably quicker.

The transformation in the appearance of this
field, which had been effected beneath my eyes,
was afterwards rendered the more striking,
when I examined in Knole Park a dense forest

Chap. III. BROUGHT UP BY WORMS.

147

of lofty beech-trees, beneath which nothing
grew. Here the ground was thickly strewed
with large naked stones, and worm-castings
were almost wholly absent. Obscure lines and
irregularities on the surface indicated that the
land had been cultivated some centuries ago.
It is probable that a thick wood of young
beech-trees sprung up so quickly, that time
enough was not allowed for worms to cover
up the stones with their castings, before the
site became unfitted for their existence. Any-
how the contrast between the state of the now
miscalled “ stony field, ” well stocked with
worms, and the present state of the ground
beneath the old beech-trees in Knole Park,
where worms appeared to be absent, was strik-
ing.

A narrow path running across part of my
lawn was paved in 1843 with small flag-stones,
set edgeways; but worms threw up many cast-
ings and weeds grew thickly between them.
During several years the path was weeded and
swept; but ultimately the weeds and worms
prevailed, and the gardener ceased to sweep,
merely mowing off the weeds, as often as the

148 AMOUNT OF EARTH Chap. III.

lawn was mowed. The path soon became al-
most covered up, and after several years no
trace of it was left. On removing, in 1877, the
thin overlying layer of turf, the small flag-
stones, all in their proper places, were found
covered by an inch of fine mould.

Two recently published accounts of sub-
stances strewed on the surface of pasture-land,
having become buried through the action of
worms, may be here noticed. The Rev. H. C.
Key had a ditch cut in a field, over which coal-
ashes had been spread, as it was believed, eigh-
teen years before; and on the clean-cut per-
pendicular sides of the ditch, at a depth of at
least seven inches, there could be seen, for a
length of 60 yards, “ a distinct, very even, nar-
row line of coal-ashes, mixed with small
coal, perfectly parallel with the top-sward.” *
This parallelism and the length of the section
gives interest to the case. Secondly, Mr.
Dancer states f that crushed bones had been
thickly strewed over a field; and “ some years
afterwards ” these were found “ several

* “ Nature,” November, 1877, p. 28.

f “ Proc. Phil. Soc.” of Manchester, 1877, p. 247.

Chap. III. BROUGHT UP BY WORMS.

149

inches below the surface, at a uniform
depth.” Worms appear to act in the same
manner in New Zealand as in Europe; for Pro-
fessor J. von Haast has described * a section
near the coast, consisting of mica-schist, “ cov-
ered by 5 or 6 feet of loess, “ above which
about 1 2 inches of vegetable soil had accumu-
lated.” Between the loess and the mould
there was a layer from 3 to 6 inches in thick-
ness, consisting of “ cores, implements, flakes,
and chips, all manufactured from hard basaltic
rock.” It is therefore probable that the abo-
rigines, at some former period, had left these
objects on the surface, and that they had after-
wards been slowly covered up by the castings
of worms.

Farmers in England are well aware that
objects of all kinds, left on the surface of pas-
ture-land, after a time disappear, or, as they
say, work themselves downwards. How pow-
dered lime, cinders, and heavy stones, can work
down, and at the same rate, through the mat-
ted roots of a grass-covered surface, is a ques-

*“ Trans, of the New Zealand Institute,” vol. xii., 1880,
p. 152.

ISO

GREAT STONES

Chap. III.

tion which has probably never occurred to
them.*

The Sinking of great Stones through the Ac-
tion of Worms . — When a stone of large size and
of irregular shape is left on the surface of the
ground, it rests, of course, on the more protu-
berant parts; but worms soon fill up with their
castings all the hollow spaces ‘on the lower
side; for, as Hensen remarks, they like the
shelter of stones. As soon as the hollows are
filled up, the worms eject the earth which they
have swallowed beyond the circumference of
the stones; and thus the surface of the ground
is raised all round the stone. As the burrows
excavated directly beneath the stone after a
time collapse, the stone sinks a little. f

* Mr. Lindsay Carnagie, in a letter (June, 1838) to Sir C. Lyell,
remarks that .Scotch farmers are afraid of putting lime on
ploughed land until just before it is laid down for pasture, from
a belief that it has some tendency to sink. He adds : “ Some
years since, in autumn, I laid lime on an oat-stubble and ploughed
it down ; thus bringing it into immediate contact with the dead
vegetable matter, and securing its thorough mixture through the
means of all the subsequent operations of fallow. In consequence
of the above prejudice, I was considered to have committed a
great fault ; but the result was eminently successful, and the
practice was partially followed. By means of Mr. Darwin’s
observations, I think the prejudice will be removed.”

f This conclusion, which, as we shall immediately see, is fully

Chap. III. UNDERMINED BY WORMS. 15 1

Hence is is, that boulders which at some an-
cient period have rolled down from a rocky
mountain or cliff on to a meadow at its base,
are always somewhat embedded in the soil;
and, when removed, leave an exact impression
of their lower surfaces in the under-lying fine
mould. If, however, a boulder is of such huge
dimensions, that the earth beneath is kept dry,
such earth will not be inhabited by worms, and
the boulder will not sink into the ground.

A lime-kiln formerly stood in a grass-field
near Leith Hill Place in Surrey, and was pulled
down 35 years before my visit; all the loose
rubbish had been carted away, excepting three
large stones of quartzose sandstone, which it
was thought might hereafter be of some use.
An old workman remembered that they had
been left on a bare surface of broken bricks and
mortar, close to the foundations of the kiln;
but the whole surrounding surface is now cov-
ered with turf and mould. The two largest of
these stones had never since been moved; nor

justified, is of some little importance, as the so-called bench-stones,
which surveyors fix in the ground as a record of their levels,
may in time become false standards. My son Horace intends at
some future period to ascertain how far this has occurred.

152

GREAT STONES

Chap. III.

could this easily have been done, as, when I
had them removed, it was the work of two men
with levers. One of these stones, and not the
largest, was 64 inches long, 17 inches broad,
and from 9 to 10 inches in thickness. Its
lower surface was somewhat protuberant in
the middle; and this part still rested on broken
bricks and mortar, showing the truth of the
old workman’s account. Beneath the brick
rubbish the natural sandy soil, full of fragments
of sandstone was found; and this could have
yielded very little, if at all, to the weight of the
stone, as might have been expected if the sub-
soil had been clay. The surface of the field,
for a distance of about 9 inches round the
stone, gradually sloped up to it, and close to
the stone stood in most places about 4 inches
above the surrounding ground. The base of
the stone was buried from 1 to 2 inches be-
neath the general level, and the upper surface
projected about 8 inches above this level, or
about 4 inches above the sloping border of
turf. After the removal of the stone it became
evident that one of its pointed ends must at
first have stood clear above the ground by

Chap. III. UNDERMINED BY WORMS.

153

some inches, but its upper surface was now
on a level with the surrounding turf. When
the stone was removed, an exact cast of its
lower side, forming a shallow crateriform hol-
low, was left, the inner surface of which con-
sisted of fine black mould, excepting where
the more protuberant parts rested on the
brick-rubbish. A transverse section of this

Fig. 6. — Transverse section across a large stone, which had lain
on a grass-field for 35 years. A A, general level of the
field. The underlying brick rubbish has not been repre-
sented. Scale $ inch to one foot.

stone, together with its bed, drawn from
measurements made after it had been displaced,
is here given on a scale of ^ inch to a foot (Fig.
6). The turf-covered border which sloped up
to the stone, consisted of fine vegetable
mould, in one part 7 inches in thickness.
This evidently consisted of worm-castings,
several of which had been recently ejected.

154

GREAT STONES

Chap. III.

The whole stone had sunk in the thirty-five
years, as far as I could judge, about inch;
and this must have been due to the brick-rub-
bish beneath the more protuberant parts hav-
ing been undermined by worms. At this rate
the upper surface of the stone, if it had been
left undisturbed, would have sunk to the gen-
eral level of the field in 247 years; but before
this could have occurred, some earth would
have been washed down by heavy rain from
the castings on the raised border of turf oyer
the upper surface of the stone.

The second stone was larger than the one
just described, viz., 67 inches in length, 39 in
breadth, and 15 in thickness. The lower sur-
face was nearly flat, so that the worms must
soon have been compelled to eject their cast-
ings beyond its circumference. The stone as
a whole had sunk about 2 inches into the
ground. At this rate it would have required
262 years for its upper surface to have sunk
to the general level of the field. The up-
wardly sloping, turf-covered border round the
stone was broader than in the last case, viz.,
from 14 to 16 inches; and why this should be

Chap. III. UNDERMINED BY WORMS.

155

so, I could see no reason. In most parts this
border was not so high as in the last case, viz.,
from 2 to 2\ inches, but in one place it was as
much as 5J. Its average height close to the
stone was probably about 3 inches, and it
thinned out to nothing. If so, a layer of fine
earth, 15 inches in breadth and i-| inch in aver-
age thickness, of sufficient length to surround
the whole of the much elongated slab, must
have been brought up by the worms in chief
part from beneath the stone in the course of 35
years. This amount would be amply suffi-
cient to account for its having sunk about 2
inches into the ground; more especially if we
bear in mind that a good deal of the finest
earth would have been washed by heavy rain
from the castings ejected on the sloping bor-
der down to the level of the field. Some fresh
castings were seen close to the stone. Never-
theless, on digging a large hole to a depth of
18 inches where the stone had lain, only two
worms and a few burrows were seen, although
the soil was damp and seemed favourable for
worms. There were some large colonies of
ants beneath the stone, and possibly since

Chap. III.

156 GREAT STONES

their establishment the worms had decreased
in number.

The third stone was only about half as
large as the others; and two strong boys
could together have rolled it over. I have
no doubt that it had been rolled over at a mod-
erately recent time, for it now lay at some dis-
tance from the other two stones at the bottom
of a little adjoining slope. It rested also on
fine earth, instead of partly on brick-rubbish.
In agreement with this conclusion, the raised
surrounding border of turf was only 1 inch
high in some parts, and 2 inches in other
parts. There were no colonies of ants be-
neath this stone, and on digging a hole where
it had lain, several burrows and worms were
found.

At Stonehenge, some of the outer Druidi-
cal stones are now prostrate, having fallen at
a remote but unknown period; and these have
become buried to a moderate depth in the
ground. They are surrounded by sloping bor-
ders of turf, on which recent castings were
seen. Close to one of these fallen stones,
which was 17 ft. long, 6 ft. broad, and 2&§

Chap. III. UNDERMINED BY WORMS.

157

inches thick, a hole was dug; and here the
vegetable mould was at least 9^ inches in
thickness. At this depth a flint was found,
and a little higher up on one side of the hole
a fragment of glass. The base of the stone
lay about 9J inches beneath the level of the
surrounding ground, and its upper surface 19
inches above the ground.

A hole was also dug close to a second huge
stone, which in falling had broken into two
pieces; and this must have happened long
ago, judging from the weathered aspect of
the fractured ends. The base was buried to
a depth of 10 inches, as was ascertained by
driving an iron skewer horizontally into the
ground beneath it. The vegetable mould
forming the turf-covered sloping border round
the stone, on which many castings had re-
cently been ejected, was 10 inches in thick-
ness; and most of this mould must have been
brought up by worms from beneath its base.
At a distance of 8 yards from the stone, the
mould was only 5! inches in thickness (with a
piece of tobacco pipe at a depth of 4 inches),
and this rested on broken flint and chalk

x58

GREAT STONES

Chap. III.

which could not have easily yielded to the
pressure or weight of the stone.

A straight rod was fixed horizontally (by
the aid of a spirit-level) across a third fallen
stone, which was 7 feet 9 inches long; and the
contour of the projecting parts and of the ad-

Fig. 7. — Section through one of the fallen Druidical stones at
Stonehenge, showing how much it had sunk into the ground.
Scale i inch to one foot.

joining ground, which was not quite level,
was thus ascertained, as shown in the accom-
panying diagram (Fig. 7) on a scale of inch
to a foot. The turf-covered border sloped up
to the stone on one side to a height of 4
inches, and on the opposite side to only 2\
inches above the general level. A hole was
dug on the eastern side, and the base of the
stone was here found to lie at a depth of 4
inches beneath the general level of the ground,

Chap. III. UNDERMINED BY WORMS.

159

and of 8 inches beneath the top of the sloping
turf-covered border.

Sufficient evidence has now been given
showing that small objects left on the surface
of the land where worms abound soon get
buried, and that large stones sink slowly
downwards through the same means. Every
step of the process could be followed, from
the accidental deposition of a single casting
on a small object lying loose on the surface,
to its being entangled amidst the matted
roots of the turf, and lastly to its being em-
bedded in the mould at various depths be-
neath the surface. When the same field was
re-examined after the interval of a few years,
such objects were found at a greater depth
than before. The straightness and regularity
of the lines formed by the embedded objects,
and their parallelism with the surface of the
land, are the most striking features of the case-;
for this parallelism shows how equably the
worms must have worked; the result being,
however, partly the effect of the washing
down of the fresh castings by rain. The spe-

i6o

NUMBER OF WORMS.

Chap. III.

cific gravity of the objects does not affect
their rate of sinking, as could be seen by por-
ous cinders, burnt marl, chalk and quartz peb-
bles, having all sunk to the same depth within
the same time. Considering the nature of the
substratum, which at Leith Hill Place was
sandy soil including many bits of rock, and at
Stonehenge, chalk-rubble with broken flints;
considering, also, the presence of the turf-cov-
ered sloping border of mould round the great
fragments of stone at both these places, their
sinking does not appear to have been sensibly
aided by their weight, though this was consid-
erable.*

On the number of worms which live within a
given space. — We will now show, firstly, what
a vast number of worms live unseen by us be-
neath our feet, and, secondly, the actual
weight of the earth which they bring up to

* Mr. R. Mallet remarks (“ Quarterly Journal of Geolog. Soc.,”
vol. xxxiii., 1877, p. 745) that “the extent to which the ground
beneath the foundations of ponderous architectural structures,
such as cathedral towers, has been known to become compressed,
is as remarkable as it is instructive and curious. The amount
of depression in some cases may be measured by feet.” He
instances the Tower of Pisa, but adds that it was founded on
“ dense clay.”

Chap. III.

NUMBER OF WORMS.

161

the surface within a given space and within a
given time. Hensen, who has published so
full and interesting an account of the habits
of worms,* calculates, from the number which
he found in a measured space, that there must
exist 133,000 living worms in a hectare of
land, or 53,767 in an acre. This latter num-
ber of worms would weigh 356 pounds, taking
Hensen’s standard of the weight of a single
worm, namely, one gram. It should, how-
ever, be noted that this calculation is founded
on the numbers found in a garden, and Hen-
sen believes that worms are here twice as nu-
merous as in corn-fields. The above result, as-
tonishing though it be, seems to me credible,
judging from the number of worms which I
have sometimes seen, and from the number
daily destroyed by birds without the species
being exterminated. Some barrels of bad ale
were left on Mr. Miller's land,f in the hope of
making vinegar, but the vinegar proved bad,
and the barrels were upset. It should be prem-

* “Zeitschrift fur wissensch. Zoolog.,” Bd. xxviii., 1877, p.
354.

f See Mr. Dancer’s paper in “ Proc. Phil. Soc. of Manches-
ter,” 1877, p. 248.

162 WEIGHT OF EARTH Chap. III.

ised that acetic acid is so deadly a poison to
worms that Perrier found that a glass rod
dipped into this acid and then into a consider-
able body of water in which worms were im-
mersed, invariably killed them quickly. On
the morning after the barrels had been upset,
“ the heaps of worms which lay dead on the
ground were so amazing, that if Mr. Miller had
not seen them, he could not have thought it
possible for such numbers to have existed in
the space.” As further evidence of the large
number of worms which live in the ground,
Hensen states that he found in a garden sixty-
four open burrows in a space of 14^ square
feet, that is, nine in 2 square feet. But the
burrows are sometimes much more numerous,
for when digging in a grass-field near Maer
Hall, I found a cake of dry earth, as large as
my two open hands, which was penetrated by
seven burrows, as large as goose-quills.

Weight of the earth ejected from a single
burrow, and from all the burrows within a given
space. — With respect to the weight of the
earth daily ejected by worms, Hensen found
that it amounted, in the case of some worms

Chap. III. BROUGHT UP BY WORMS.

163

which he kept in confinement, and which he
appears to have fed with leaves, to only 0.5
gram, or less than 8 grains per diem. But a
very much larger amount must be ejected by
worms in their natural state, at the periods
when they consume earth as food instead of
leaves, and when they are making deep bur-
rows. This is rendered almost certain by the
following weights of the castings thrown up at
the mouths of single burrows; the whole of
which appeared to have been ejected within no
long time, as was certainly the case in several
instances. The castings were dried (excepting
in one specified instance) by exposure during
many days to the sun or before a hot fire.

Weight of the Castings accumulated at the Mouth
of a Single Burrow.

(1.) Down, Kent (sub-soil red clay, full of flints, overly- '
ing the chalk). — The largest casting which I could
find on the flanks of a steep valley, the sub-soil being V
here shallow. In this one case, the casting was not
well dried

(2.) Down. — Largest casting which I could find (con- '
sisting chiefly of calcareous matter), on extremely I
poor pasture land at the bottom of the valley men- ‘
tioned under (i.)

(3.) Down. — A large casting, but not of unusual size, i
from a nearly level field, poor pasture, laid down in
grass about 35 years before . . . . . . . . j

(4.) Down. — Average weight of 11 not large castings
ejected on a sloping surface on my lawn, after they I
had suffered some loss of weight from being exposed j
during a considerable length of time to rain . . J

Ounces.

3.98

3-87

1.22

0.7

164

WEIGHT OF EARTH

Chap. III.

Weight of the Castings accumulated at the Mouth
of A Single Burrow — continued.

(5.) Near Nice in France. — Average weight of 12 cast-"
ings of ordinary dimensions, collected by Dr. King
on land which had not been mown for a long time
and where worms abounded, viz., a lawn protected
by shrubberies, near the sea : soil sandy and calcare- -
ous ; these castings had been exposed for some time
to rain, before being collected, and must have lost
some weight by disintegration, but they still retained
their form . . . . . . . . . . . .

(6.) The heaviest of the above twelve castings
(7.) Lower Bengal. — Average weight of 22 castings, )
collected by Mr. J. Scott, and stated by him to have >•
been thrown up in the course of one or two nights )
(8.) The heaviest of the above 22 castings
(9.) Nilgiri Mountains, S. India; average weight of the")
5 largest castings collected by Dr. King. They had (
been exposed to the rain of the last monsoon, and |
must have lost some weight . . . . . . . . J

(10.) The heaviest of the above 5 castings

Ounces.

i-37

1.76

1.24

2.09

3- i5

4- 34

In this table we see that castings which
had been ejected at the mouth of the same
burrow, and which in most cases appeared
fresh and always retained their vermiform
configuration, generally exceeded an ounce in
weight after being dried, and sometimes nearly
equalled a quarter of a pound. On the Nil-
giri mountains one casting even exceeded this
latter weight. The largest castings in Eng-
land were found on extremely poor pasture-
land; and these, as far as I have seen, are gen-
erally larger than those on land producing a
rich vegetation. It would appear that worms

Chap. III. BROUGHT UP BY WORMS.

165

have to swallow a greater amount of earth on
poor than on rich land, in order to obtain suffi-
cient nutriment.

With respect to the tower-like castings
near Nice (Nos. 5 and 6 in the above table),
Dr. King often found five or six of them on a
square foot of surface; and these, judging
from their average weight, would have
weighed together ounces; so that the
weight of those on a square yard would have
been 4 lb. 3^ oz. Dr. King collected, near the
close of the year 1872, all the castings which
still retained their vermiform shape, whether
broken down or not, from a square foot, in a
place abounding with worms, on the summit
of a bank, where no castings could have rolled
down from above. These castings must have
been ejected, as he judged from their appear-
ance in reference to the rainy and dry periods
near Nice, within the previous five or six
months; they weighed 9J oz., or 5 lb. 5J oz.
per square yard. After an interval of four
months Dr. King collected all the castings sub-
sequently ejected on the same square foot of
surface, and they weighed 2-J oz., or 1 lb. 6J oz.

1 66 WEIGHT OF EARTH Chap. III.

per square yard. Therefore within about ten
months, or we will say for safety’s sake within
a year, 12 oz. of castings were thrown up on
this one square foot, or 6.75 pounds on the
square yard; and this would give 14.58 tons
per acre.

In a field at the bottom of a valley in the
chalk (see No. 2 in the foregoing table), a
square yard was measured at a spot where
very large castings abounded; they appeared,
however, almost equally numerous in a few
other places. These castings, which retained
perfectly their vermiform shape, were col-
lected; and they weighed when partially dried,
1 lb. 13^ oz. This field had been rolled with
a heavy agricultural roller fifty-two days be-
fore, and this would certainly have flattened
every single casting on the land. The weather
had been very dry for two or three weeks before
the day of collection, so that not one casting
appeared fresh or had been recently ejected.
We may therefore assume that those which
were weighed had been ejected within, we will
say, forty days from the time when the field
was rolled, — that is, twelve days short of the

Chap. III. BROUGHT UP BY WORMS. 167

whole intervening period. I had examined the
same part of the field shortly before it was
rolled, and it then abounded with fresh cast-
ings. Worms do not work in dry weather
during the summer, or in winter during severe
frosts. If we assume that they work for only
half the year — though this is too low an esti-
mate-then the worms in this field would
eject during the year, 8.387 pounds per square
yard; or 18.12 tons per acre, assuming the
whole surface to be equally productive in cast-
ings.

In the foregoing cases some of the neces-
sary data had to be estimated, but in the two
following cases the results are much more
trustworthy. A lady, on whose accuracy I
can implicitly rely, offered to collect during a
year all the castings thrown up on two sepa-
rate square yards, near Leith Hill Place, in
Surrey. The amount collected was, however,
somewhat less than that originally ejected by
the worms; for, as I have repeatedly observed,
a good deal of the finest earth is washed away,
whenever castings are thrown up during or
shortly before heavy rain. Small portions

1 68 WEIGHT OF EARTH Chap. III.

also adhered to the surrounding blades of
grass, and it required too much time to detach
every one of them. On sandy soil, as in the
present instance, castings are liable to crumble
after dry weather, and particles were thus
often lost. The lady also occasionally left
home for a week or two, and at such times the
castings must have suffered still greater loss
from exposure to the weather. These losses
were, however, compensated to some extent
by the collections having been made on one of
the squares for four days, and on the other
square for two days more than the year.

A space was selected (October 9th, 1870)
on a broad, grass-covered terrace, which had
been mowed and swept during many years.
It faced the south, but was shaded during part
of the day by trees. It had been formed at
least a century ago by a great accumulation
of small and large fragments of sandstone,
together with some sandy earth, rammed
down level. It is probable that it was at
first protected by being covered with turf.
This terrace, judging from the number of cast-
ings on it, was rather unfavourable for the ex-

Chap. III. BROUGHT UP BY WORMS.

169

istence of worms, in comparison with the
neighbouring fields and an upper terrace. It
was indeed surprising that as many worms
could live here as were seen; for on digging
a hole in this terrace, the black vegetable
mould together with the turf was only four
inches in thickness, beneath which lay the
level surface of light-coloured sandy soil, with
many fragments of sandstone. Before any
castings were collected all the previously ex-
isting ones were carefully removed. The
last day’s collection was on October 14th,
1871. The castings were then well dried
before a fire; and they weighed exactly 3! lbs.
This would give for an acre of similar land
7.56 tons of dry earth annually ejected by
worms.

The second square was marked on unen-
closed common land, at a height of about
700 ft. above the sea, at some little distance
from Leith Hill Tower. The surface was
clothed with short, fine turf, and had never
been disturbed by the hand of man. The spot
selected appeared neither particularly favour-
able nor the reverse for worms; but I have
12

170 WEIGHT OF EARTH Chap. III.

often noticed that castings are especially
abundant on common land, and this may, per-
haps, be attributed to the poorness of the soil.
The vegetable mould was here between three
and four inches in thickness. As this spot
was at some distance from the house where
the lady lived, the castings were not collected
at such short intervals of time as those on the
Terrace; consequently the loss of fine earth
during rainy weather must have been greater
in this than in the last case. The castings
moreover were more sandy, and in collecting
them during dry weather they sometimes
crumbled into dust, and much was thus lost.
Therefore it is certain that the worms brought
up to the surface considerably more earth
than that which was collected. The last col-
lection was made on October 27th, 1871 ; i. e.,
367 days after the square had been marked
out and the surface cleared of all pre-existing
castings. The collected castings, after
being well dried, weighed 7.453 pounds;
and this would give, for an acre of the same
kind of land, 16.1 tons of annually ejected dry
earth.

Chap. III. BROUGHT UP BY WORMS.

171

Summary of the Four Foregoing Cases.

(1.) Castings ejected near Nice within about a year, collected
by Dr. King on a square foot of surface, calculated to yield per
acre 14.58 tons.

(2.) Castings ejected during about 45 days on a square
yard, in a field of poor pasture at the bottom of a large
valley in the Chalk, calculated to yield annually per acre
18.12 tons.

(3.) Castings collected from a square yard on an old ter-
race at Leith Hill Place, during 369 days, calculated to yield
annually per acre 7.56 tons.

(4.) Castings collected from a square yard on Leith Hill
Common during 367 days, calculated to yield annually per acre
16. 1 tons.

The thickness of the layer of mould , which
castings ejected during a year would form if uni-
formly spread out . — As we know from the last
two cases in the above summary, the weight of
the dried castings ejected by worms during a
year on a square yard of surface, I wished to
learn how thick a layer of ordinary mould this
amount would form if spread uniformly over
a square yard. The dry castings were there-
fore broken into small particles, and whilst be-
ing placed in a measure were well shaken and
pressed down. Those collected on the Ter-
race amounted to 124.77 cubic inches; and
this amount, if spread out over a square yard,

172

THICKNESS OF THE MOULD Chap. III.

would make a layer .09612 inch in thickness.
Those collected on the Common amounted to
197.56 cubic inches, and would make a similar
layer .1524 inch in thickness.

These thicknesses must, however, be cor-
rected, for the triturated castings, after being
well shaken down and pressed, did not make
nearly so compact a mass as vegetable mould,
though each separate particle was very com-
pact. Yet mould is far from being compact,
as is shown by the number of air-bubbles
which rise up when the surface is flooded with
water. It is moreover penetrated by many
fine roots. To ascertain approximately by
how much ordinary vegetable mould would be
increased in bulk by being broken up into
small particles and then dried, a thin oblong-
block of somewhat argillaceous mould (with
the turf pared off) was measured before being
broken up, was well dried and again measured.
The drying caused it to shrink by -y of its
original bulk, judging from exterior measure-
ments alone. It was then triturated and part-
ly reduced to powder, in the same manner as
the castings had been treated, and its bulk

Chap. III. ANNUALLY ACCUMULATED.

173

now exceeded (notwithstanding shrinkage
from drying) by -jV that of the original block
of damp mould. Therefore the above calcu-
lated thickness of the layer, formed by the
castings from the Terrace, after being damped
and spread over a square yard, would have to
be reduced by and this will reduce the
layer to .09 of an inch, so that a layer .9 inch
in thickness would be formed in the course of
ten years. On the same principle the castings
from the Common would make in the course
of a single year a layer .1429 inch, or in the
course of 10 years 1.429 inch, in thickness.
We may say in round numbers that the thick-
ness in the former case would amount to near-
ly 1 inch, and in the second case to nearly 1^
inch in 10 years.

In order to compare these results with
those deduced from the rates at which small
objects left on the surfaces of grass fields be-
come buried (as described in the early part of
this chapter), we will give the following sum-
mary : —

174

THICKNESS OF THE MOULD Chap. III.

Summary of the Thickness of the Mould accumulated
over Objects left strewed on the Surface, in the
Course of Ten Years.

The accumulation of mould during I4f years on the surface
of a dry, sandy, grass-field near Maer Hall, amounted to 2.2
inches in 10 years.

The accumulation during 2I-J years on a swampy field near
Maer Hall, amounted to nearly 1.9 inch in 10 years.

The accumulation during 7 years on a very swampy field near
Maer Hall amounted to 2.1 inches in 10 years.

The accumulation during 29 years, on good, argillaceous
pasture-land over the Chalk at Down, amounted to 2.2 inches in
10 years.

The accumulation during 30 years on the side of a valley over
the Chalk at Down, the soil being argillaceous, very poor, and
only just converted into pasture (so that it was for some years
unfavourable for worms), amounted to 0.83 inches in 10 years.

In these cases (excepting the last) it may
be seen that the amount of earth brought
to the surface during io years is somewhat
greater than that calculated from the castings
which were actually weighed. This excess
may be partly accounted for by the loss which
the weighed castings had previously under-
gone through being washed by rain, by the
adhesion of particles to the blades of the sur-
rounding grass, and by their crumbling when
dry. Nor must we overlook other agencies
which in all ordinary cases add to the amount
of mould, and which would not be included in

Chap. III. ANNUALLY ACCUMULATED.

175

the castings that were collected, namely, the
fine earth brought up to the surface by burrow-
ing larvae and insects, especially by ants. The
earth brought up by moles generally has a
somewhat different appearance from vegeta-
ble mould; but after a time would not be dis-
tinguishable from it. In dry countries more-
over the wind plays an important part in car-
rying dust from one place to another, and
even in England it must add to the mould on
fields near great roads. But in our county
these latter several agencies appear to be of
quite subordinate importance in comparison
with the action of worms.

We have no means of judging how great a
weight of earth a single full-sized worm ejects
during a year. Hensen estimates that 53,767
worms exist in an acre of land; but this is
founded on the number found in gardens, and
he believes that only about half as many live
in corn-fields. How many live in old pasture-
land is unknown; but if we assume that half
the above number, or 26,886 worms live on
such land, then taking from the previous sum-
mary 15 tons as the weight of the castings an-

1 76 THICKNESS OF THE MOULD Chap. III.

nually thrown up on an acre of land, each
worm must annually eject 20 ounces. A full-
sized casting at the mouth of a single burrow
often exceeds, as we have seen, an ounce in
weight; and it is probable that worms eject
more than twenty full-sized castings during a
year. If they eject annually more than 20
ounces, we may infer that the worms which
live in an acre of pasture-land must be less
than 26,886 in number.

Worms live chiefly in the superficial
mould, which is usually from 4 or 5 to 10 and
even 12 inches in thickness; and it is this
mould which passes over and over again
through their bodies and is brought to the
surface. But worms occasionally burrow into
the sub-soil to a much greater depth, and on
such occasions they bring up earth from this
greater depth; and this process has gone on
for countless ages. Therefore the superficial
layer of mould would ultimately attain,
though at a slower and slower rate, a thick-
ness equal to the depth to which worms ever
burrow, were there not other opposing agen-
cies at work which carry away to a lower level

Chap. III. ANNUALLY ACCUMULATED.

i/7

some of the finest earth which is continually
being brought to the surface by worms. How
great a thickness vegetable mould ever at-
tains, I have not had good opportunities for
observing; but in the next chapter, when we
consider the burial of ancient buildings, some
facts will be given on this head. In the last
two chapters we shall see that the soil is actu-
ally increased, though only to a small degree,
through the agency of worms; but their chief
work is to sift the finer from the coarser parti-
cles, to mingle the whole with vegetable de-
bris, and to saturate it with their intestinal se-
cretions.

Finally, no one who considers the facts
given in this chapter — on the burying of small
objects and on the sinking of great stones left
on the surface — on the vast number of worms
which live within a moderate extent of ground
— on the weight of the castings ejected from
the mouth of the same burrow — on the weight
of all the castings ejected within a known time
on a measured space — will hereafter, as I be-
lieve, doubt that worms play an important
part in nature.

CHAPTER IV.

THE PART WHICH WORMS HAVE PLAYED IN THE
BURIAL OF ANCIENT BUILDINGS.

The accumulation of rubbish on the sites of great cities inde-
pendent 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 debris by which the remains are covered — The penetration
of the tessellated 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.

Archaeologists are probably not aware
how much they owe to worms for the preser-
vation of many ancient objects. Coins, gold
ornaments, stone implements, &c., if dropped
on the surface of the ground, will infallibly be
buried by the castings of worms in a few years,
and will thus be safely preserved, until the land
at some future time is turned up. For in-
stance, many years ago a grass-field was
178

Chap. IV.

OF ANCIENT BUILDINGS.

179

ploughed on the northern side of the Severn,
not far from Shrewsbury; and a surprising
number of iron arrow-heads were found at the
bottom of the furrows, which, as Mr. Blake-
way, a local antiquary, believed were relics of
the battle of Shrewsbury in the year 1403, and
no doubt had been originally left strewed on
the battle-field. In the present chapter, I
shall show that not only implements, &c., are
thus preserved, but that the floors and the re-
mains of many ancient buildings in England
have been buried so effectually, in large part
through the action of worms, that they have
been discovered in recent times solely through
various accidents. The enormous beds of
rubbish, several yards in thickness, which un-
derlie many cities, such as Rome, Paris, and
London, the lower ones being of great an-
tiquity, are not here referred to, as they have
not been in any way acted on by worms.
When we consider how much matter is daily
brought into a great city for building, fuel,
clothing and food, and that in old times when
the roads were bad and the work of the scav-
enger was neglected, a comparatively small

i8o

BURIAL OF THE REMAINS Chap. IV.

amount was carried away, we may agree with
Elie de Beaumont, who, in discussing this sub-
ject, says, “ pour une voiture de materiaux
“ qui en sort, on y en fait entrer cent.” * Nor
should we overlook the effects of fires, the
demolition of old buildings, and the removal of
rubbish to the nearest vacant space.

Abinger, Surrey. — Late in the autumn of
1876, the ground in an old farm-yard at this
place was dug to a depth of 2 to 2J feet, and
the workmen found various ancient remains.
This led Mr. T. H. Farrer of Abinger Hall to
have an adjoining ploughed field searched.
On a trench being dug, a layer of concrete,
still partly covered with tesserae (small red
tiles), and surrounded on two sides by broken-
down walls, was soon discovered. It is be-
lieved f that this room formed part of the
atrium or reception-room of a Roman villa.
The walls of two or three other small rooms
were afterwards discovered. Many frag-
ments of pottery, other objects, and coins of

* “ Le£ons de Geologie pratique/’ 1845, p. 142.

f A short account of this discovery was published in “ The
Times” of January 2, 1878; and a fuller account in “The
Builder/’ January 5, 1878.

Chap. IV.

OF ANCIENT BUILDINGS.

1 8 1

several Roman emperors, dating from 133 to
361, and perhaps to 375 a.d., were likewise
found. Also a half-penny of George I., 1715.
The presence of this latter coin seems an
anomaly; but no doubt it was dropped on the
ground during the last century, and since then
there has been ample time for its burial under
a considerable depth of the castings of worms.
From the different dates of the Roman coins
we may infer that the building was long in-
habited. It was probably ruined and deserted
1400 or 1500 years ago.

I was present during the commencement of
the excavations (August 20, 1877) and Mr.
Farrer had two deep trenches dug at opposite
ends of the atrium, so that I might examine
the nature of the soil near the remains. The
field sloped from east to west at an angle of
about 70; and one of the two trenches, shown
in the accompanying section (Fig. 8) was at
the upper or eastern end. The diagram is on
the scale of of an inch to an inch; but the
trench, which was between 4 and 5 feet broad,
and in parts above 5 feet deep, has necessarily
been reduced out of all proportion. The fine

182 BURIAL OF THE REMAINS Chap. IV.

Fig. 8. — Section through the foundations of a buried Roman
villa at Abinger. A A, vegetable mould ; B, dark earth full
of stones, 13 inches in thickness ; C, black mould ; D, broken
mortar ; E, black mould ; F F, undisturbed sub-soil ; G, tes- ,
serae ; H, concrete ; I, nature unknown ; W, buried wall.

Chap. IV. OF ANCIENT BUILDINGS. 183

mould over the floor of the atrium varied in
thickness from 11 to 16 inches; and on the
side of the trench in the section was a little
over 13 inches. After the mould had been
removed, the floor appeared as a whole mod-
erately level; but it sloped in parts at an angle
of i°, and in one place near the outside at as
much as 8° 30'. The wall surrounding the
pavement was built of rough stones, and was
23 inches in thickness where the trench was
dug. Its broken summit was here 13 inches,
but in another part 15 inches, beneath the
surface of the field, being covered by this
thickness of mould. In one spot, however,
it rose to within 6 inches of the surface. On
two sides of the room, where the junction of
the concrete floor with the bounding walls
could be carefully examined, there was no
crack or separation. This trench afterwards
proved to have been dug within an adjoining
room (11 ft. by 11 ft. 6 in. in size), the exist-
ence of which was not even suspected whilst
I was present.

On the side of the trench farthest from the
buried wall (W), the mould varied from 9 to

1 84 BURIAL OF THE REMAINS Chap. IV.

14 inches in thickness; it rested on a mass
(B) 23 inches thick of blackish earth, includ-
ing many large stones. Beneath this was a
thin bed of very black mould (C), then a layer
of earth full of fragments of mortar (D), and
then another thin bed (about 3 inches thick)
(F) of very black mould, which rested on the
undisturbed subsoil (F) of firm, yellowish, ar-
gillaceous sand. The 23-inch bed (B) was
probably made ground, as this would have
brought up the floor of the room to a level
with that of the atrium. The two thin beds
of black mould at the bottom of the trench
evidently marked two former land-surfaces.
Outside the walls of the northern room, many
bones, ashes, oyster-shells, broken pottery
and an entire pot were subsequently found at
a depth of 16 inches beneath the surface.

The second trench was dug on the western
or lower side of the villa: the mould was here
only 6\ inches in thickness, and it rested on a
mass of fine earth full of stones, broken tiles
and fragments of mortar, 34 inches in thick-
ness, beneath which was the undisturbed sand.
Most of this earth had probably been washed

Chap. IV. OF ANCIENT BUILDINGS. 185

down from the upper part of the field, and the
fragments of stones, tiles, &c., must have
come from the immediately adjoining ruins.

It appears at first sight a surprising fact that
this field of light sandy soil should have been
cultivated and ploughed during many years,
and that not a vestige of these buildings
should have been discovered. No one even
suspected that the remains of a Roman villa
lay hidden close beneath the surface. But the
fact is less surprising when it is known that
the field, as the bailiff believed, had never
been ploughed to a greater depth than 4
inches. It is certain that when the land was
first ploughed, the pavement and the sur-
rounding broken walls must have been cov-
ered by at least 4 inches of soil, for otherwise
the rotten concrete floor would have been
scored by the ploughshare, the tesserae torn
up, and the tops of the old walls knocked
down.

When the concrete and tesserae were first
cleared over a space of 14 by 9 ft., the floor
which was coated with trodden-down earth

exhibited no signs of having been penetrated

13

1 86 BURIAL OF THE REMAINS Chap. IV.

by worms; and although the overlying fine
mould closely resembled that which in many
places has certainly been accumulated by
worms, yet it seemed hardly possible that this
mould could have been brought up by worms
from beneath the apparently sound floor. It
seemed also extremely improbable that the
thick walls, surrounding the room and still
united to the concrete, had been undermined
by worms, and had thus been caused to sink,
being afterwards covered up by their castings.
I therefore at first concluded that all the fine
mould above the ruins had been washed down
from the upper parts of the field; but we shall
soon see that this conclusion was certainly
erroneous, though much fine earth is known to
be washed down from the upper part of the field
in its present ploughed state during heavy
rains.

Although the concrete floor did not at first
appear to have been anywhere penetrated by
worms, yet by the next morning little cakes of
the trodden-down earth had been lifted up by
worms over the mouths of seven burrows,
which passed through the softer parts of the

Chap. IV. OF ANCIENT BUILDINGS. 187

naked concrete, or between the interstices of
the tesserae. On the third morning, twenty-
five burrows were counted; and by suddenly
lifting up the little cakes of earth, four worms
were seen in the act of quickly retreating.
Two castings were thrown up during the third
night on the floor, and these were of large size.
The season was not favourable for the full ac-
tivity of worms, and the weather had lately
been hot and dry, so that most of the worms
now lived at a considerable depth. In dig-
ging the two trenches many open burrows and
some worms were encountered at between 30
and 40 inches beneath the surface; but at a
greater depth they became rare. One worm,
however, was cut through at 48^, and another
at 51^ inches beneath the surface. A fresh
humus-lined burrow was also met with at a
depth of 57 and another at 65^ inches. At
greater depths than this, neither burrows nor
worms were seen.

As I wished to learn how many worms
lived beneath the floor of the atrium — a space
of about 14 by 9 feet — Mr. Farrer was so kind
as to make observations for me, during the

i88

BURIAL OF THE REMAINS Chap. IV.

next seven weeks, by which time the worms
in the surrounding country were in full activ-
ity, and were working near the surface. It is
eery improbable that worms should have mi-
grated from the adjoining fields into the small
space of the atrium, after the superficial mould
in which they prefer to live, had been removed.
We may therefore conclude that the burrows
and the castings which were seen here during
the ensuing seven weeks were the work of the
former inhabitants of the space. I will now
give a few extracts from Mr. Farrer’s notes.

Aug. 26th, 1877; that isj five days after
the floor had been cleared. On the previous
night there had been some heavy rain, which
washed the surface clean, and now the mouths
of forty burrows were counted. Parts of the
concrete were seen to be solid, and had never
been penetrated by worms, and here the rain-
water lodged.

Sept. 5th. — Tracks of worms, made during
the previous night, could be seen on the sur-
face of the floor, and five or six vermiform
castings had been thrown up. These were de-
faced.

Chap. IV. OF ANCIENT BUILDINGS. 189

Sept. 12 th.- — During the last six days, the
worms have not been active, though many
castings have been ejected in the neighbour-
ing fields; but on this day the earth was a
little raised over the mouths of the burrows,
or castings were ejected, at ten fresh points.
These were defaced. It should be understood
that when a fresh burrow is spoken of, this
generally means only that an old burrow has
been re-opened. Mr. Farrer was repeatedly
struck with the pertinacity with which the
worms re-opened their old burrows, even
when no earth was ejected from them. I
have often observed the same fact, and gen-
erally the mouths of the burrows are protected
by an accumulation of pebbles, sticks or leaves.
Mr. Farrer likewise observed that the worms
living beneath the floor of the atrium often
collected coarse grains of sand, and such little
stones as they could find, round the mouths
of their burrows.

Sept. 13th; soft wet weather. The
mouths of the burrows were re-opened, or
castings were ejected, at 31 points; these
were all defaced.

190

BURIAL OF THE REMAINS Chap. IV.

Sept. 14th; 34 fresh holes or castings all
defaced.

Sept. 15th; 44 fresh holes, only 5 castings;
all defaced.

Sept. 18th; 43 fresh holes, 8 castings; all
defaced.

The number of castings on the surround-
ing fields was now very large.

Sept. 19th; 40 holes, 8 castings; all de-
faced.

Sept. 22nd; 43 holes, only a few fresh cast-
ings; all defaced.

Sept. 23rd; 44 holes, 8 castings.

Sept. 25th; 50 holes, no record of the num-
ber of castings.

Oct. 13th; 61 holes, no record of the
number of castings.

After an interval of three years, Mr. Farrer,
at my request, again looked at the concrete
floor, and found the worms still at work.

Knowing what great muscular power
worms possess, and seeing how soft the con-
crete was in many parts, I was not surprised at
its having been penetrated by their burrows;
but it is a more surprising fact that the mor-

Chap. IV.

OF ANCIENT BUILDINGS.

I9I

tar between the rough stones of the thick
walls surrounding the rooms, was found by
Mr. Farrer to have been penetrated by worms.
On August 26th, that is, five days after the
ruins had been exposed, he observed four open
burrows on the broken summit of the eastern
wall (W in Fig. 8); and, on September 15th,
other burrows similarly situated were seen.
It should also be noted that in the perpendicu-
lar side of the trench (which was much deeper
than is represented in Fig. 8) three recent bur-
rows were seen, which ran obliquely far down
beneath the base of the old wall.

We thus see that many worms lived be-
neath the floor and the walls of the atrium at
the time when the excavations were made;
and that they afterwards almost daily brought
up earth to the surface from a considerable
depth. There is not the slightest reason to
doubt that worms have acted in this manner
ever since the period when the concrete was
sufficiently decayed to allow them to pene-
trate it; and even before that period they
would have lived beneath the floor, as soon as
it became pervious to rain, so that the soil be-

BURIAL OF THE REMAINS Chap. IV.

192

neath was kept damp. The floor and the
walls must therefore have been continually
undermined; and fine earth must have been
heaped on them during many centuries, per-
haps for a thousand years. If the burrows be-
neath the floor and walls, which it is probable
were formerly as numerous as they now are,
had not collapsed in the course of time in the
manner formerly explained, the underlying
earth would have been riddled with passages
like a sponge; and as this was not the case,
we may feel sure that they have collapsed.
The inevitable result of such collapsing during
successive centuries, will have been the slow
subsidence of the floor and of the walls, and
their burial beneath the accumulated worm-
castings. The subsidence of a floor, whilst it
still remains nearly horizontal, may at first ap-
pear improbable; but the case presents no
more real difficulty than that of loose objects
strewed on the surface of a field, which, as we
have seen, become buried several inches be-
neath the surface in the course of a few years,
though still forming a horizontal layer parallel
to the surface. The burial of the paved and

Chap. IV. OF ANCIENT BUILDINGS.

193

level path on my lawn, which took place under
my own observation, is an analogous case.
Even those parts of the concrete floor which
the worms could not penetrate would almost
certainly have been undermined, and would
have sunk, like the great stones at Leith Hill
Place and Stonehenge, for the soil would have
been damp beneath them. But the rate of
sinking of the different parts would not have
been quite equal, and the floor was not quite
level. The foundations of the boundary walls
lie, as shown in the section, at a very small
depth beneath the surface; they would there-
fore have tended to subside at nearly the same
rate as the floor. But this would not have oc-
curred if the foundations had been deep, as in
the case of some other Roman ruins presently
to be described.

Finally, we may infer that a large part of
the fine vegetable mould, which covered the
floor and the broken-down walls of this vifla,
in some places to a thickness of 16 inches, was
brought up from below by worms. From
facts hereafter to be given there can be no
doubt that some of the finest earth thus

194

BURIAL OF THE REMAINS Chap. IV.

brought up will have been washed down the
sloping surface of the field during every heavy
shower of rain. If this had not occurred a
greater amount of mould would have accumu-
lated over the ruins than that now present.
But beside the castings of worms and some
earth brought up by insects, and some accumu-
lation of dust, much fine earth will have been
washed over the ruins from the upper parts of
the field, since it has been under cultivation;
and from over the ruins to the lower parts of
the slope; the present thickness of the mould
being the resultant of these several agencies.

I may here append a modern instance of
the sinking of a pavement, communicated to
me in 1871 by Mr. Ramsay, Director of the
Geological Survey of England. A passage
without a roof, 7 feet in length by 3 feet 2
inches in width, led from his house into the
garden, and was paved with slabs of Portland
stone. Several of these slabs were 16 inches
square, others larger, and some a little smaller.
This pavement had subsided about 3 inches
along the middle of the passage, and 2

Chap, IV.

OF ANCIENT BUILDINGS.

I95

inches on each side, as could be seen by the
lines of cement by which the slabs had been
originally joined to the walls. The pavement
had thus become slightly concave along the
middle; but there was no subsidence at the
end close to the house. Mr. Ramsay could
not account for this sinking, until he observed
that castings of black mould were frequently
ejected along the lines of junction between
the slabs; and these castings were regularly
swept away. The several lines of junction,
including those with the lateral walls, were al-
together 39 feet 2 inches in length. The
pavement did not present the appearance of
ever having been renewed and the house was
believed to have been built about eighty-seven
years ago. Considering all these circum-
stances, Mr. Ramsay does not doubt that the
earth brought up by the worms since the
pavement was first laid down, or rather since
the decay of the mortar allowed the worms
to burrow through it, and therefore within
a much shorter time than the eighty-seven
years, has sufficed to cause the sinking of the
pavement to the above amount, except close

196

BURIAL OF THE REMAINS Chap. IV.

to the house, where the ground beneath would
have been kept nearly dry.

Beaulieu Abbey , Hampshire . — This abbey
was destroyed by Henry VIII., and there now
remains only a portion of the southern aisle-
wall. It is believed that the king had most of
the stones carried away for building a castle;
and it is certain that they have been removed.
The position of the nave-transept was ascer-
tained not long ago by the foundations having
been found; and the place is now marked by
stones let into the ground. Where the abbey
formerly stood, there now extends a smooth
grass-covered surface, which resembles in all
respects the rest of the field. The guardian, a
very old man, said the surface had never been
levelled in his time. In the year 1853, the
Duke of Buccleuch had three holes dug in the
turf within a few yards of one another, at the
western end of the nave; and the old tessel-
lated pavement of the abbey was thus discov-
ered. These holes were afterwards surround-
ed by brickwork, and protected by trap-doors,
so that the pavement might be readily inspect-
ed and preserved. When my son William ex-

Chap. IV.

OF ANCIENT BUILDINGS.

I97

amined the place on January 5, 1872, he found
that the pavement in the three holes lay at
depths of 6§, 10 and n± inches beneath the
surrounding turf-covered surface. The old
guardian asserted that he was often forced to
remove worm-castings from the pavement;
and that he had done so about six months be-
fore. My son collected all from one of the
holes, the area of which was 5.32 square feet,
and they weighed 7.97 ounces. Assuming
that this amount had accumulated in six
months, the accumulation during a year on a
square yard would be 1.68 pounds, which,
though a large amount, is very small com-
pared with what, as we have seen, is often
ejected on fields and commons. When I
visited the abbey on June 22, 1877, the old
man said that he had cleared out the holes
about a month before, but a good many cast-
ings had since been ejected. I suspect that he
imagined that he swept the pavements oftener
than he really did, for the conditions were in
several respects very unfavourable for the ac-
cumulation of even a moderate amount of
castings. The tiles are rather large, viz.,

198

BURIAL OF THE REMAINS Chap. IV.

about 5^ inches square, and the mortar be-
tween them was in most places sound, so that
the worms were able to bring up earth from
below only at certain points. The tiles rested
on a bed of concrete, and the castings in con-
sequence consisted in large part (viz., in the
proportion of 19 to 33) of particles of mortar,
grains of sand, little fragments of rock, bricks*
or tile; and such substances could hardly be
agreeable, and certainly not nutritious, to
worms.

My son dug holes in several places within
the former walls of the abbey, at a distance of
several yards from the above-described bricked
squares. He did not find any tiles, though
these are known to occur in some other parts,
but he came in one spot to concrete on which
tiles had once rested. The fine mould be-
neath the turf on the sides of the several holes,
varied in thickness from only 2 to 2 f inches,
and this rested on a layer from 8| to above 1 1
inches in thickness, consisting of fragments of
mortar and stone-rubbish with the interstices
compactly filled up with black mould. In
the surrounding field, at a distance of 20 yards

Chap. IV.

OF ANCIENT BUILDINGS.

I99

from the abbey, the fine vegetable mould was
1 1 inches thick.

We may conclude from these facts that
when the abbey was destroyed and the stones
removed, a layer of rubbish was left over the
whole surface, and that as soon as the worms
were able to penetrate the decayed concrete
and the joints between the tiles, they slowly
filled up the interstices in the overlying rub-
bish with their castings, which were after-
wards accumulated to a thickness of nearly
three inches over the whole surface. If we
add to this latter amount the mould between
the fragments of stones, some five or six
inches of mould must have been brought up
from beneath the concrete or tiles. The con-
crete or tiles will consequently have subsided
to nearly this amount. The bases of the
columns of the aisles are now buried beneath
mould and turf. It is not probable that they
can have been undermined by worms, for
their foundations would no doubt have been
laid at a considerable depth. If they have
not subsided, the stones of which the col-
umns were constructed must have been re-

200

BURIAL OF THE REMAINS Chap. IV.

moved from beneath the former level of the
floor.

Chedworth , Gloucestershire . — The remains
of a large Roman villa were discovered here
in 1866, on ground which had been covered
with wood from time immemorial. No sus-
picion seems ever to have been entertained that
ancient buildings lay buried here, until a game-
keeper, in digging for rabbits, encountered
some remains.* But subsequently the tops
of some stone walls were detected in parts of
the wood, projecting a little above the surface
of the ground. Most of the coins found here
belonged to Constans (who died 350 a.d.) and
the Constantine family. My sons Francis and
Horace visited the place in November 1877,
for the sake of ascertaining what part worms
may have played in the burial of these exten-
sive remains. But the circumstances were
not favourable for this object, as the ruins are
surrounded on three sides by rather steep

* Several accounts of these ruins have been published ; the
best is by Mr. James Farrer in “ Proc. Soc. of Antiquaries of
Scotland,” vol. vi., Part II., 1867, p. 278. Also J. W. Grover,
“Journal of the British Arch. Assoc.,” June, 1866. Professor
Buckman has likewise published a pamphlet, “Notes on the
Roman Villa at Chedworth,” 2nd edit., 1873 : Cirencester.

Chap. IV.

OF ANCIENT BUILDINGS.

201

banks, down which earth is washed during
rainy weather. Moreover most of the old
rooms have been covered with roofs, for the
protection of the elegant tessellated pave-
ments.

A few facts may, however, be given on
the thickness of the soil over these ruins.
Close outside the northern rooms there is a
broken wall, the summit of which was covered
by 5 inches of black mould; and in a hole dug
on the outer side of this wall, where the
ground had never before been disturbed, black
mould, full of stones, 26 inches in thickness,
was found, resting on the undisturbed sub-soil
of yellow clay. At a depth of 22 inches from
the surface a pig's jaw and a fragment of a tile
were found. When the excavations were first
made, some large trees grew over the ruins;
and the stump of one has been left directly
over a party-wall near the bath-room, for the
sake of showing the thickness of the superin-
cumbent soil, which was here 38 inches. In
one small room, which, after being cleared out,
had not been roofed over, my sons observed
the hole of a worm passing through the rotten
14

202

BURIAL OF THE REMAINS Chap. IV.

concrete, and a living worm was found within
the concrete. In another open room worm-
castings were seen on the floor, over which
some earth had by this means been deposited,
and here grass now grew.

Brading, Isle of Wight. — A fine Roman
villa was discovered here in 1880; and by the
end of October no less than 18 chambers had
been more or less cleared. A coin dated 337
a.d. was found. My son William visited the
place before the excavations were completed;
and he informs me that most of the floors were
at first covered with much rubbish and fallen
stones, having their interstices completely
filled up with mould, abounding, as the work-
men said, with worms, above which there was
mould without any stones. The whole mass
was in most places from 3 to above 4 ft. in
thickness. In one very large room the over-
lying earth was only 2 ft. 6 in. thick; and after
this had been removed, so many castings were
thrown up between the tiles that the surface
had to be almost daily swept. Most of the
floors were fairly level. The tops of the
broken-down walls were covered in some

Chap. IV.

OF ANCIENT BUILDINGS.

203

places by only 4 or 5 inches of soil, so that
they were occasionally struck by the plough,
but in other places they were covered by from
13 to 18 inches of soil. It is not probable that
these walls could have been undermined by
worms and subsided, as they rested on a foun-
dation of very hard red sand, into which
worms could hardly burrow. The mortar,
however, between the stones of the walls of
a hypocaust was found by my son to have been
penetrated by many worm-burrows. The re-
mains of this villa stand on land which slopes
at an angle of about 30; and the land appears
to have been long cultivated. Therefore no
doubt a considerable quantity of fine earth has
been washed down from the upper parts of the
field, and has largely aided in the burial of
these remains.

Silchester, Hampshire. — The ruins of this
small Roman town have been better preserved
than any other remains of the kind in England.
A broken wall, in most parts from 15 to 18
feet in height, and about i^ mile in compass,
now surrounds a space of about 100 acres of
cultivated land, on which a farm-house and a

204

BURIAL OF THE REMAINS Chap. IV.

church stand.* Formerly, when the weather
was dry, the lines of the buried walls could be
traced by the appearance of the crops; and
recently very extensive excavations have been
undertaken by the Duke of Wellington, under
the superintendence of the late Rev. J. G.
Joyce, by which means many large buildings
have been discovered. Mr. Joyce made care-
ful coloured sections, and measured the thick-
ness of each bed of rubbish, whilst the exca-
vations were in progress; and he has had the
kindness to send me copies of several of them.
When my sons Francis and Horace visited
these ruins, he accompanied them, and added
his notes to theirs.

Mr. Joyce estimates that the town was in-
habited by the Romans for about three cen-
turies; and no doubt much matter must have
accumulated within the walls during this long
period. It appears to have been destroyed by
fire, and most of the stones used in the build-
ings have since been carried away. These cir-
cumstances are unfavourable for ascertaining

* These details are taken from the “ Penny Encyclopaedia,”
article, Hampshire.

Chap. IV.

OF ANCIENT BUILDINGS.

205

the part which worms have played in the
burial of the ruins; but as careful sections of
the rubbish overlying an ancient town have sel-

Fig. 9. — Section within a room in the Basilica at Silchester.
Scale tV*

206

BURIAL OF THE REMAINS Chap. IV.

dom or never before been made in England, I
will give copies of the most characteristic por-
tions of some of those made by Mr. Joyce.
They are of too great length to be here intro-
duced entire.

An east and west section, 30 ft. in length,
was made across a room in the Basilica, now
called the Hall of the Merchants (Fig. 9).
The hard concrete floor, still covered here and
there with tesserae, was found at 3 ft. beneath
the surface of the field, which was here level.
On the floor there were two large piles of
charred wood, one alone of which is shown in
the part of the section here given. This pile
was covered by a thin white layer of decayed
stucco or plaster, above which was a mass,
presenting a singularly disturbed appearance,
of broken tiles, mortar, rubbish and fine
gravel, together 27 inches in thickness. Mr.
Joyce believes that the gravel was used in
making the mortar or concrete, which has
since decayed, some of the lime probably
having been dissolved. The disturbed state
of the rubbish may have been due to its
having been searched for building stones.

Chap. IV.

OF ANCIENT BUILDINGS.

This bed was capped by fine vegetable mould,

*5 ju £

Fig. io. — Section within a hall in the Basilica at Silchester.
Scale -3^.

208

BURIAL OF THE REMAINS Chap. IV.

9 inches in thickness. From these facts we
may conclude that the Hall was burnt down,
and that much rubbish fell on the floor,
through and from which the worms slowly
brought up the mould, now forming the sur-
face of the level field.

A section across the middle of another hall
in the Basilica, 32 feet 6 inches in length,
called the (Evarium, is shown in Fig. 10. It
appears that we have here evidence of two
fires, separated by an interval of time, during
which the 6 inches of “ mortar and concrete
with broken tiles ” was accumulated. Be-
neath one of the layers of charred wood, a
valuable relic, a bronze eagle, was found; and
this shows that the soldiers must have de-
serted the place in a panic. Owing to the
death of Mr. Joyce, I have not been able to as-
certain beneath which of the two layers the
eagle was found. The bed of rubble overlying
the undisturbed gravel originally formed, as
I suppose, the floor, for it stands on a level
with that of a corridor, outside the walls of
the Hall; but the corridor is not shown in
the section as here given. The vegetable

Chap. IV.

OF ANCIENT BUILDINGS.

209

mould was 16 inches thick in the thickest
part; and the depth from the surface of the
field, clothed with herbage, to the undisturbed
gravel, was 40 inches.

Mould, 20 inches
thick.

Rubble with
broken tiles, 4
inches thick.

Black decayed
wood, in thick-
est part 6 inches
thick.

Gravel.

Fig. 11. — Section in a block of buildings in the middle of the
town of Silchester.

The section shown in Fig. n represents
an excavation made in the middle of the town,
and is here introduced because the bed of

210

BURIAL OF THE REMAINS Chap. IV.

“ rich mould ” attained, according to Mr.
Joyce, the unusual thickness of 20 inches.
Gravel lay at the depth of 48 inches from the

Mould, q inches
thick.

Light-coloured earth
with large pieces
of broken tiles, 7
inches.

Dark, . fine-grained
rubbish with small
bits of tiles 20
inches.

Concrete, 4 inches.
Stucco, 2 inches.

Made bottom with
fragments of tiles,
8 inches.

Fine - grained made
ground with the
debris of older
buildings.

Fig. 12. — Section in the centre of the Basilica at Silchester.

surface; but it was not ascertained whether
this was in its natural state, or had been

Chap. IV.

OF ANCIENT BUILDINGS.

2 1 1

brought here and had been rammed down, as
occurs in some other places.

The section shown in Fig. 12 was taken
in the centre of the Basilica, and though it
was 5 feet in depth, the natural sub-soil was
not reached. The bed marked “ concrete ”
was probably at one time a floor; and the beds
beneath seem to be the remnants of more an-
cient buildings. The vegetable mould was
here only 9 inches thick. In some other sec-
tions, not copied, we likewise have evidence of
buildings having been erected over the ruins
of older ones. In one case there was a layer
of yellow clay of very unequal thickness be-
tween two beds of debris, the lower one of
which rested on a floor with tesserae. The old
broken walls appear sometimes to have been
roughly cut down to a uniform level, so as to
serve as the foundations of a temporary build-
ing; and Mr. Joyce suspects that some of
these buildings were wattled sheds, plastered
with clay, which would account for the above-
mentioned layer of clay.

Turning now to the points which more
immediately concern us. Worm-castings

212

BURIAL OF THE REMAINS Chap. IV.

were observed on the floors of several of the
rooms, in one of which the tessellation was un-
usually perfect. The tesserae here consisted
of little cubes of hard sandstone of about I
inch, several of which were loose or projected
slightly above the general level. One or oc-
casionally two open worm-burrows were found
beneath all the loose tesserae. Worms have
also penetrated the old walls of these ruins.
.A wall, which had just been exposed to view
during the excavations then in progress, was
examined: it was built of large flints, and was
1 8 inches in thickness. It appeared sound,
but when the soil was removed from beneath,
the mortar in the lower part was found to be
so much decayed that the flints fell apart from
their own weight. Here, in the middle of the
wall, at a depth of 29 inches beneath the old
floor and of 49J inches beneath the surface of
the field, a living worm was found, and the
mortar was penetrated by several burrows.

A second wall was exposed to view for the
first time, and an open burrow was seen on
its broken summit. By separating the flints
this burrow was traced far down in the interior

Chap. IV. OF ANCIENT BUILDINGS. 213

of the wall; but as some of the flints cohered
firmly, the whole mass was disturbed in pull-
ing down the wall, and the burrow could not
be traced to the bottom. The foundations of
a third wall, which appeared quite sound, lay
at a depth of 4 feet beneath one of the floors,
and of course at a considerably greater depth
beneath the level of the ground. A large
flint was wrenched out of the wall at about a
foot from the base, and this required much
force, as the mortar was sound; but behind
the flint in the middle of the wall, the mortar
was friable, and here there were worm-bur-
rows. Mr. Joyce and my sons were surprised
at the blackness of the mortar in this and in
several other cases, and at the presence of
mould in the interior of the walls. Some may
have been placed there by the old builders in-
stead of mortar; but we should remember
that worms line their burrows with black hu-
mus. Moreover open spaces would almost
certainly have been occasionally left between
the large irregular flints; and these spaces, we
may feel sure, would be filled up by the worms
with their castings, as soon as they were able

North. Horizontal line. South,

BURIAL OF THE REMAINS Chap. IV.

214

to penetrate the wall. Rain-
water, oozing down the bur-
rows would also carry fine
dark-coloured particles into
every crevice. Mr. Joyce was
at first very sceptical about
the amount of work which I
attributed to worms; but he
ends his notes with reference
to the last-mentioned wall by
saying, “ This case caused me
more surprise and brought
more conviction to me than
any other. I should have said,
and did say, that it wTas quite
impossible such a wall could
have been penetrated by earth-
worms.”

In almost all the rooms the
pavement has sunk consider-
ably, especially towards the
middle; and this is shown in
the three following sections.
The measurements were made
by stretching a string tightly

Chap. IV.

OF ANCIENT BUILDINGS.

215

and horizontally over the floor. The section,
Fig. 13, was taken from north to south across
a room, 18 feet 4 inches in length, with a
nearly perfect pavement, next to the “ Red
Wooden Hut.” In the northern half, the sub-
sidence amounted to 5! inches beneath the
level of the floor as it now stands close to the
walls; and it was greater in the northern than
in the southern half; but, according to Mr.
Joyce, the entire pavement has obviously sub-
sided. In several places, the tesserae appeared
as if drawn a little away from the walls; whilst
in other places they were still in close contact
with them.

In Fig. 14, we see a section across the
paved floor of the southern corridor or ambu-
latory of a quadrangle, in an excavation made
near “ The Spring.” The floor is 7 feet 9
inches wide, and the broken-down walls now
project only § of an inch above its level. The
field, which was in pasture, here sloped from
north to south, at an angle of 30 40'. The na-
ture of the ground on each side of the corridor
is shown in the section. It consisted of earth
full of stones and other debris, capped with

2l6

BURIAL OF THE REMAINS

Chap. IV.

*

Nature of the ground beneath the tesserae unknown. Silchester. Scale 3V*

Chap. IV.

OF ANCIENT BUILDINGS.

217

dark vegetable mould which was thicl cer 011
the lower or southern than on the no\rt^ern
side. The pavement was nearly level along
lines parallel to the side-walls, but had. sunk
in the middle as much as 7J inches.

A small room at no great distance ■ from
that represented in Fig. 13, had been enkfr§ed
by the Roman occupier on the southern
by an addition of 5 feet 4 inches in breC
For this purpose the southern wall ofi
house had been pulled down, but the four
tions of the old wall had been left buried
little depth beneath the pavement of thei en“
larged room. Mr. Joyce believes that yhis
buried wall must have been built before ^ie
reign of Claudius II., who died 270 a. d.
see in the accompanying section, Fig. 15, tliat
the tessellated pavement has subsided to a
less degree over the buried wall than ek’e”

where; so that a slight convexity or prot^u"
berance here stretched in a straight line acro4ss
the room. This led to a hole being dug, an d
the buried wall was thus discovered.

We see in these three sections, and in sev
eral others not given, that the old pavement

Chap. IV.

OF ANCIENT BUILDINGS.

have sunk or sagged considerably. Mr. Joyce
formerly attributed this sinking solely to the
slow settling of the ground. That there has
been some settling is highly probable, and it
may be seen in section 15 that the pavement
for a width of 5 feet over the southern en-
largement of the room, which must have been
built on fresh ground, has sunk a little more
than on the old northern side. But this sink-
ing may possibly have had no connection with
the enlargement of the room, for in Fig. 13,
one half of the pavement has subsided more
than the other half without any assignable
cause. In a bricked passage to Mr. Joyce’s
own house, laid down only about six years
ago, the same kind of sinking has occurred as
in the ancient buildings. Nevertheless it does
not appear probable that the whole amount of
sinking can be thus accounted for. The Ro-
man builders excavated the ground to an un-
usual depth for the foundations of their walls,
which were thick and solid; it is therefore
hardly credible that they should have been
careless about the solidity of the bed on which
their tessellated and often ornamented pave-

220

BURIAL OF THE REMAINS Chap. IV.

ments were laid. The sinking must, as it ap-
pears to me, be attributed in chief part to the
pavement having been undermined by worms,
which we know are still at work. Even Mr.
Joyce at last admitted that this could not have
failed to have produced a considerable effect.
Thus also the large quantity of fine mould
overlying the pavements can be accounted for,
the presence of which would otherwise be in-
explicable. My sons noticed that in one room
in which the pavement had sagged very little,
there was an unusally small amount of overly-
ing mould.

As the foundations of the walls generally
lie at a considerable depth, they will either
have not subsided at all through the under-
mining action of worms, or they will have sub-
sided much less than the floor. This latter
result would follow from worms not often
working deep down beneath the foundations;
but more especially from the walls not yield-
ing when penetrated by worms, whereas the
successively formed burrows in a mass of
earth, equal to one of the walls in depth and
thickness, would have collapsed many times

[

Chap. IV. OF ANCIENT BUILDINGS. 221*

since the desertion of the ruins, and would
consequently have shrunk or subsided. As
the walls cannot have sunk much or at all, the
immediately adjoining pavement from adher-
ing to them will have been prevented from
subsiding; and thus the present curvature of
the pavement is intelligible.

The circumstance which has surprised me
most with respect to Silchester is that during
the many centuries which have elapsed since
the old buildings were deserted, the vegetable
mould has not accumulated over them to a
greater thickness than that here observed. In
most places it is only about 9 inches in thick-
ness, but in some places 12 or even more
inches. In Fig. 11, it is given as 20 inches,
but this section was drawn by Mr. Joyce be-
fore his attention was particularly called to
this subject. The land enclosed within the
old walls is described as sloping slightly to the
south; but there are parts which, according to
Mr. Joyce, are nearly level, and it appears that
the mould is here generally thicker than else-
where. The surface slopes in other parts from
west to east, and Mr. Joyce describes one floor

222

BURIAL OF THE REMAINS Chap. IV.

as covered at the western end by rubbish and
mould to a thickness of 2&| inches, and at the
eastern end by a thickness of only inches.
A very slight slope suffices to cause recent
castings to flow downwards during heavy
rain, and thus much earth will ultimately
reach the neighbouring rills and streams and
be carried away. By this means, the absence
of very thick beds of mould over these ancient
ruins may, as I believe, be explained. More-
over most of the land here has long been
ploughed, and this would greatly aid the wash-
ing away of the finer earth during rainy
weather.

The nature of the beds immediately be-
neath the vegetable mould in some of the
sections is rather perplexing. We see, for in-
stance, in the section of an excavation in a
grass meadow (Fig. 14), which sloped from
north to south at an angle of 30 40', that the
mould on the upper side is only six inches and
on the lower side nine inches in thickness.
But this mould lies on a mass (25^ inches in
thickness on the upper side) “ of dark brown
mould,” as described by Mr. Joyce, “ thickly

Chap. IV.

OF ANCIENT BUILDINGS.

223

interspersed with small pebbles and bits of
tiles, which present a corroded or worn ap-
pearance. The state of this dark-coloured
earth is like that of a field which has long been
ploughed, for the earth thus becomes inter-
mingled with stones and fragments of all kinds
which have been much exposed to the weather.

If during the course of many centuries this
grass meadow and the other now cultivated
fields have been at times ploughed, and at
other times left as pasture, the nature of the
ground in the ab*ove section is rendered in-
telligible. For worms will continually have
brought up fine earth from below, which will >
have been stirred up by the plough whenever
the land was cultivated. But after a time a
greater thickness of fine earth will thus have
been accumulated than could be reached by
the plough; and a bed like the 25^-inch mass,
in Fig. 14, will have been formed beneath the
superficial mould, which latter will have been
brought to the surface within more recent
times, and have been well sifted by the worms.

Wroxeter , Shropshire. — The old Roman
city of Uriconium was founded in the early

224

BURIAL OF THE REMAINS Chap. IV.

part of the second century, if not before this
date, and it was destroyed, according to Mr.
Wright, probably between the middle of the
fourth and fifth century. The inhabitants
were massacred, and skeletons of women were
found in the hypocausts. Before the year
1859, the sole remnant of the city above
ground, was a portion of a massive wall about
20 ft. in height. The surrounding land undu-
lates slightly, and has long been under cultiva-
tion. It had been noticed that the corn-crops
ripened prematurely in certain narrow lines,
and that the snow remained unmelted in cer-
tain places longer than in others. These ap-
pearances led, as I was informed, to extensive
excavations being undertaken. The founda-
tions of many large buildings and several
streets have thus been exposed to view. The
space enclosed within the old walls is an ir-
regular oval, about if mile in length. Many
of the stones or bricks used in the buildings
must have been carried away; but the hypo-
causts, baths, and other underground build-
ings were found tolerably perfect, being filled
with stones, broken tiles, rubbish and soil.

OF ANCIENT BUILDINGS.

Chap. IV.

225

The old floors of various rooms were covered
with rubble. As I was anxious to know how
thick the mantle of mould and rubbish was,
which had so long concealed these ruins, I ap-
plied to Dr. H. Johnson, who had superintend-
ed the excavations; and he, with the greatest
kindness, twice visited the place to examine it
in reference to my questions, and had many
trenches dug in four fields which had hitherto
been undisturbed. The results of his obser-
vations are given in the following Table. He
also sent me specimens of the mould, and an-
swered, as far as he could, all my questions.

Measurements by Dr. H. Johnson of the. Thickness of
the Vegetable Mould over the Roman Ruins at
Wroxeter.

Trenches dug in a field called “ Old
Works.”

Thickness
of mould in
inches.

1. At a depth of 36 inches undisturbed sand was

reached . . . . . . . . . . 20

2. At a depth of 33 inches concrete was reached 21

3. “ “ 9 inches concrete was reached 9

Trenches dug in a field called “ Shop Lea-
sows;.” this is the highest field within the

226

BURIAL OF THE REMAINS Chap. IV.

old walls, and slopes down from a sub-central
point on all sides at about an angle of 2°.

Thickness
of mould in
inches.

4. Summit of field, trench 45 inches deep . . 40

5. Close to summit of field, trench 36 inches deep 26

6. “ “ trench 28 inches deep 28

7. Near summit of field, trench 36 inches deep 24

8. “ “ trench at one end 39

inches deep ; the mould here graduated into
the underlying undisturbed sand, and its
thickness is somewhat arbitrary. At the
other end of the trench, a causeway was en-
countered at a depth of only 7 inches, and

the mould was here only 7 inches thick . . 24

9. Trench close to the last, 28 inches in depth . . 15

10. Lower part of same field, trench 30 inches deep 15

11. “ “ trench 31 inches deep 17

12. “ “ trench 36 inches deep,

at which depth undisturbed sand was reached 28

13. In another part of same field, trench 9^ inches

deep, stopped by concrete . . . . . . 9-J

14. In another part of same field, trench 9 inches

deep, stopped by concrete . . . . . . 9

15. In another part of the same field, trench 24

inches deep, when sand was reached . . 16

16. In another part of same field, trench 30 inches

deep, when stones were reached ; at one end
of the trench mould 12 inches, at the other
end 14 inches thick . . . . . . 13

Small field between “ Old Works ” and
“ Shop Leasows,” I believe nearly as high as
the upper part of the latter field.

Chap. IV.

OF ANCIENT BUILDINGS.

227

Thickness
of mould in
inches.

17. Trench 26 inches deep . . . . . . 24

18. “ 10 inches deep, and then came upon a

causeway . . . . . . . . . . 10

ig. Trench 34 inches deep . . . . . . . . 30

20. “ 31 inches deep . . . . . . . . 31

Field on the western side of the space en-
closed within the old walls.

Thickness
of mould in
inches.

21. Trench 28 inches deep, when undisturbed sand

was reached . . . . . . . . 16

22. Trench 29 inches deep, when undisturbed sand

was reached . . . . . . . . . . 15

23. Trench 14 inches deep, and then came upon a

building . . . . . . . . 14

Dr. Johnson distinguished as mould the
earth which differed, more or less abruptly, in
its dark colour and in its texture from the
underlying sand or rubble. In the specimens
sent to me, the mould resembled that which
lies immediately beneath the turf in old pas-
ture-land, excepting that it often contained
small stones, too large to have passed through
the bodies of worms. But the trenches above
described were dug in fields, none of which
were in pasture, and all had been long culti-
vated. Bearing in mind the remarks made in

228

BURIAL OF THE REMAINS Chap. IV.

reference to Silchester on the effects of long-
continued culture, combined with the action
of worms in bringing up the finer particles to
the surface, the mould, as so designated by
Dr. Johnson, seems fairly well to deserve its
name. Its thickness, where there was no
causeway, floor or walls beneath, was greater
than has been elsewhere observed, namely in
many places above 2 ft., and in one spot above
3 ft. The mould was thickest on and close to
the nearly level summit of the field called
“ Shop Leasows,” and in a small adjoining
field, which, as I believe, is of nearly the same
height. One side of the former field slopes at
an angle of rather above 2°, and I should have
expected that the mould from being washed
down during heavy rain, would have been
thicker in the lower than in the upper part;
but this was not the case in two out of the
three trenches here dug.

In many places, where streets ran beneath
the surface, or where old buildings stood, the
mould was only 8 inches in thickness; and Dr.
Johnson was surprised that in ploughing the
land, the ruins had never been struck by the

Chap. IV.

OF ANCIENT BUILDINGS.

229

plough as far as he had heard. He thinks that
when the land was first cultivated the old walls
were perhaps intentionally pulled down, and
that hollow places were filled up. This may
have been the case; but if after the desertion
of the city the land was left for many centuries
uncultivated, worms would have brought up
enough fine earth to have covered the ruins
completely; that is if they had subsided from
having been undermined. The foundations of
some of the walls, for instance those of the
portion still standing about 20 feet above the
ground, and those of the market-place, lie at
the extraordinary depth of 14 feet; but it is
highly improbable that the foundations were
generally so deep. The mortar employed in
the buildings must have been excellent, for it
is still in parts extremely hard. Wherever
walls of any height have been exposed to view,
they are, as Dr. Johnson believes, still perpen-
dicular. The walls with such deep founda-
tions cannot have been undermined by worms,
and therefore cannot have subsided, as appears
to have occurred at Abinger and Silchester.
Hence it is very difficult to account for their

230

BURIAL OF THE REMAINS Chap. IV.

being now completely covered with earth; but
how much of this covering consists of vegeta-
ble mould and how much of rubble I do not
know. The market-place, with the founda-
tions at a depth of 14 feet, was covered up, as
Dr. Johnson believes, by between 6 and 24
inches of earth. The tops of the broken-
down walls of a caldarium or bath, 9 feet in
depth, were likewise covered up with nearly 2
feet of earth. The summit of an arch, leading
into an ash-pit 7 feet in depth, was covered up
with not more than 8 inches of earth. When-
ever a building which has not subsided is cov-
eered with earth, we must suppose, either that
the upper layers of stone have been at some
time carried away by man, or that earth has
since been washed down during heavy rain, or
blown down during storms, from the adjoin-
ing land; and this would be especially apt to
occur where the land has long been cultivated.
In the above cases the adjoining land is some-
what higher than the three specified sites, as
far as I can judge by maps and from informa-
tion give me by Dr. Johnson. If, however, a
great pile of broken stones, mortar, plaster,

Chap. IV.

OF ANCIENT BUILDINGS.

23I

timber, and ashes fell over the remains of any
building, their disintegration in the course of
time, and the sifting action of worms, would
ultimately conceal the whole beneath fine
earth.

Conclusion. — The cases given in this chap-
ter show that worms have played a consider-
able part in the burial and concealment of sev-
eral Roman and other old buildings in Eng-
land; but no doubt the washing down of soil
from the neighbouring higher lands, and the
deposition of dust, have together added large-
ly in the work of concealment. Dust would
be apt to accumulate wherever old broken-
down walls projected a little above the then
existing surface and thus afforded some shel-
ter. The floors of the old rooms, halls and
passages have generally sunk, partly from the
settling of the ground, but chiefly from having
been undermined by worms; and the sinking
has commonly been greater in the middle than
near the walls. The walls themselves, when-
ever their foundations do not lie at a great
depth, have been penetrated and undermined

232

BURIAL OF THE REMAINS. Chap. IV.

by worms, and have consequently subsided.
The unequal subsidence thus caused, probably
explains the great cracks which may be seen
in many ancient walls, as well as their inclina-
tion from the perpendicular.

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 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 mill-stones — The levi-
gated 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.

No one doubts that our world at one time
consisted of crystalline rocks, and that it is
to their disintegration through the action of
air, water, changes of temperature, rivers,
waves of the sea, earthquakes and volcanic out-
bursts, that we owe our sedimentary forma-
tions. These after being consolidated and

sometimes recrystallized, have often been again

16 233

234

DISINTEGRATION

Chap. V.

disintegrated. Denudation means the removal
of such disintegrated matter to a lower level.
Of the many striking results due to the mod-
ern progress of geology there are hardly any
more striking than those which relate to
denudation. It was long ago seen that there
must have been an immense amount of denu-
dation; but until the successive formations
were carefully mapped and measured, no one
fully realised how great was the amount. One
of the first and most remarkable memoirs ever
published on this subject was that by Ram-
say,* who in 1846 showed that in Wales from
9,000 to 11,000 feet in thickness of solid rock
had been stripped off large tracts of country.
Perhaps the plainest evidence of great denu-
dation is afforded by faults or cracks, which ex-
tend for many miles across certain districts,
with the strata on one side raised even ten
thousand feet above the corresponding strata
on the opposite side; and yet there is not a
vestige of this gigantic displacement visible
on the surface of the land. A huge pile of

* “ On the denudation of South Wales,” &c., “ Memoirs of
the Geological Survey of Great Britain,” vol. i. p. 297, 1846.

Chap. V.

AND DENUDATION.

23S

rock has been planed away on one side and not
a remnant left.

Until the last twenty or thirty years, most
geologists thought that the waves of the*sea
were the chief agents in the work of denuda-
tion; but we may now feel sure that air and
rain, aided by streams and rivers, are much
more powerful agents, — that is if we consider
the whole area of the land. The long lines of
escarpment which stretch across several parts
of England were formerly considered to be un-
doubtedly ancient coast-lines; but we now
know that they stand up above the general
surface merely from resisting air, rain and frost
better than the adjoining formations. It has
rarely been the good fortune of a geologist to
bring conviction to the minds of his fellow-
workers on a disputed point by a single mem-
oir; but Mr. Whitaker, of the Geological
Survey of England, was so fortunate when, in
1867, he published his paper “ On sub-aerial
Denudation, and on Cliffs and Escarpments of
the Chalk.” * Before this paper appeared,

* 44 Geological Magazine,” October and November, 1867, vol.
iv. pp. 447 and 483. Copious references on the subject are given
in this remarkable memoir.

236 DISINTEGRATION Chap. V.

Mr. A. Tylor had adduced important evidence
on sub-aerial denudation, by showing that the
amount of matter brought down by rivers must
infallibly lower the level of their drainage-
basins by many feet in no immense lapse of
time. This line of argument has since been
followed up in the most interesting manner by
Archibald Geikie, Croll and others, in a series
of valuable memoirs.* For the sake of those
who have never attended to this subject, a sin-
gle instance may be here given, namely that of
the Mississippi, which is chosen because the
amount of sediment brought down by this
great river has been investigated with especial
care by order of the United States Govern-
ment. The result is, as Mr. Croll shows, that
the mean level of its enormous area of drain-

* A. Tylor “ On changes of the sea-level,” &c., “Philosophical
Mag.” (Ser. 4th), vol. v., 1853, p. 258. Archibald Geikie,
“Transactions Geolog. Soc. of Glasgow,” vol. iii. p, 153 (read
March, 1868). Croll “ On Geological Time,” “ Philosophical
Mag.,” May, August, and November, 1868. See also Croll,
“Climate and Time,” 1875, Chap. XX. For some recent in-
formation on the amount of sediment brought down by rivers,
see “Nature,” Sept. 23rd, 1880. Mr. T. Mellard Reade has
published some interesting articles on the astonishing amount
of matter brought down in solution by rivers. See Address,
Geolog. Soc., Liverpool, 1 876-77.

Chap. V.

AND DENUDATION.

237

age must be lowered of a foot annually,

or 1 foot in 4566 years. Consequently, tak-
ing the best estimate of the mean height of
the North American continent, viz. 748 feet,
and looking to the future, the whole of the
Mississippi basin will be washed away, and
“ brought down to the sea-level in less than
4,500,000 years, if no elevation of the land
takes place.” Some rivers carry down much
more sediment relatively to their size, and some

much less than the Mississippi.

%

Disintegrated matter is carried away by
the wind as well as by running water. Dur-
ing volcanic outbursts much rock is triturated
and is thus widely dispersed; and in all arid
countries the wind plays an important part in
the removal of such matter. Wind-driven
sand also wears down the hardest rocks. I
have shown * that during four months of the
year a large quantity of dust is blown from the
north-western shores of Africa, and falls on
the Atlantic over a space of 1600 miles in lati-
tude, and for a distance of from 300 to 600

* “An account of the fine dust which often falls on vessels in
the Atlantic Ocean,” Proc. Geolog. Soc. of London, June 4, 1845.

238 DISINTEGRATION Chap. V.

miles from the coast. But dust has been seen
to fall at a distance of 1030 miles from the
shores of Africa. During a stay of three weeks
at St. Jago in the Cape Verde Archipelago,
the atmosphere was almost always hazy, and
extremely fine dust coming from Africa was
continually falling. In some of this dust which
fell in the open ocean at a distance of between
330 and 380 miles from the African coast, there
were many particles of stone, about toVo °f an
inch square. Nearer to the coast the water has
been seen to be so much discoloured by the fall-
ing dust, that a sailing vessel left a track be-
hind her. In countries, like the Cape Verde
Archipelago, where it seldom rains and there
are no frosts, the solid rock nevertheless dis-
integrates; and in conformity with the views
lately advanced by a distinguished Belgian
geologist, De Koninck, such disintegration
may be attributed in chief part to the action of
the carbonic and nitric acids, together with
the nitrates and nitrites of ammonia, dissolved
in the dew.

In all humid, even moderately humid,
countries, worms aid in the work of denuda-

Chap. V.

AND DENUDATION.

239

tion in several ways. The vegetable mould
which covers, as with a mantle, the surface of
the land, has all passed many times through
their bodies. Mould differs in appearance
from the subsoil only in its dark colour, and in
the absence of fragments or particles of stone
(when such are present in the subsoil), larger
than those which can pass through the alimen-
tary canal of a worm. This sifting of the soil
is aided, as has already been remarked, by bur-
rowing animals of many kinds, especially by
ants. In countries where the summer is long
and dry, the mould in protected places must
be largely increased by dust blown from other
and more exposed places. For instance, the
quantity of dust sometimes blown over the
plains of La Plata, where there are no solid
rocks, is so great, that during the “ gran seco,”
1827 to 1830, the appearance of the land, which
is here unenclosed, was so completely changed
that the inhabitants could not recognise the
limits of their own estates, and endless lawsuits
arose. Immense quantities of dust are like-
wise blown about in Egypt and in the south of
France. In China, as Richthofen maintains,

240

DISINTEGRATION

Chap. V.

beds appearing like fine sediment, several hun-
dred feet in thickness and extending over an
enormous area, owe their origin to dust blown
from the high lands of central Asia.* In
humid countries like Great Britain, as long as
the land remains in its natural state clothed
with vegetation, the mould in any one place
can hardly be much increased by dust; but in
its present condition, the fields near high roads,
where there is much traffic, must receive a con-
siderable amount of dust, and when fields are
harrowed during dry and windy weather, clouds
of dust may be seen to be blown away. But
in all these cases the surface-soil is merely
transported from one place to another. The
dust which falls so thickly within our houses
consists largely of organic matter, and if
spread over the land would in time decay and

* For La Plata, see my “Journal of Researches,” during the
voyage of the B eagle , 1845, p. 133. Elie de Beaumont has
given (“ Le9ons de Geolog. pratique,” tom. 1., 1845, p. 183) an
excellent account of the enormous quantity of dust which is
transported in some countries. I cannot but think that Mr.
Proctor has somewhat exaggerated (“ Pleasant Ways in Science,”
1879, p. 379) the agency of dust in a humid country like Great
Britain. James Geikie has given (“Prehistoric Europe,” 1880,
p. 165) a full abstract of Richthofen’s views, which, however,
he disputes.

Chap. V.

AND DENUDATION.

24I

disappear almost entirely. It appears, how-
ever, from recent observations on the snow-
fields of the Arctic regions, that some little
meteoric dust of extra mundane origin is con-
tinually falling.

The dark colour of ordinary mould is ob-
viously due to the presence of decaying or-
ganic matter, which, however, is present in but
small quantities. The loss of weight which
mould suffers when heated to redness seems
to be in large part due to water in combina-
tion being dispelled. In one sample of fertile
mould the amount of organic matter was as-
certained to be only 1.76 per cent.; in some
artificially prepared soil it was as much as 5.5
per cent., and in the famous black soil of Russia
from 5 to even 12 per cent.* In leaf-mould
formed exclusively by the decay of leaves the
amount is much greater, and in peat the
carbon alone sometimes amounts to 64 per
cent.; but with these latter cases we are not
here concerned. The carbon in the soi1 tends

* These statements are taken from Von Hensen in “Zeit-
schrift fur wissenschaft. Zoologie,” Bd. xxviii., 1877, p. 360.
Those with respect to peat are taken from Mr. A. A. Julien in
“ Proc. American Assoc. Science,” 1879, P* S1^

242

DISINTEGRATION

Chap. V.

gradually to oxidise and to disappear, except
where water accumulates and the climate is
cool; * so that in the oldest pasture-land there
is no great excess of organic matter, notwith-
standing the continued decay of the roots and
the underground stems of plants, and the oc-
casional addition of manure. The disappear-
ance of the organic matter from mould is prob-
ably much aided by its being brought again
and again to the surface in the castings of
worms.

Worms, on the other hand, add largely to
the organic matter in the soil by the astonish-
ing number of half-decayed leaves which they
draw into their burrows tp a depth of 2 or 3
inches. They do this chiefly for obtaining
food, but partly for closing the mouths of their
burrows and for lining the upper part. The
leaves which they consume are moistened,
torn into small shreds, partially digested, and
intimately commingled with earth; and it is
this process which gives to vegetable mould
its uniform dark tint. It is known that vari-

* I have given some facts on the climate necessary or favour-
able for the formation of peat, in my “Journal of Researches/*
1845, p. 287.

Chap. V.

AND DENUDATION.

243

ous kinds of acids are generated by the decay
of vegetable matter; and from the contents
of the intestines of worms and from their cast-
ings being acid, it seems probable that the pro-
cess of digestion induces an analogous chemi-
cal change in the swallowed, triturated, and
half-decayed leaves. The large quantity of
carbonate of lime secreted by the calciferous
glands apparently serves to neutralise the
acids thus generated; for the digestive fluid of
worms will not act unless it be alkaline. As
the contents of the upper part of their intes-
tines are acid, the acidity can hardly be due
to the presence of uric acid. We may there-
fore conclude that the acids in the alimentary
canal of worms are formed during the digest-
ive process; and that probably they are nearly
of the same nature as those in ordinary hu-
mus. The latter are well known to have the
power of de-oxidising or dissolving peroxide
of iron, as may be seen wherever peat overlies
red sand, or where a rotten root penetrates
such sand. Now I kept some worms in a pot
filled with very fine reddish sand, consisting of
minute particles of silex coated with the red

244

DISINTEGRATION

Chap. V.

oxide of iron; and the burrows, which the
worms made through this sand, were lined or
coated in the usual manner with their castings,
formed of the sand mingled with their intes-
tinal secretions and the refuse of the digested
leaves; and this sand had almost wholly lost
its red colour. When small portions of it
were placed under the microscope, most of
the grains were seen to be transparent and
colourless, owing to the dissolution of the ox-
ide; whilst almost all the grains taken from
other parts of the pot were coated with the
oxide. Acetic acid produced hardly any effect
on this sand; and even hydrochloric, nitric
and sulphuric acids, diluted as in the Pharma-
copoeia, produced less effect than did the acids
in the intestines of the worms.

Mr. A. A. Julien has lately collected all
the extant information about the acids gen-
erated in humus, which, according to some
chemists, amount to more than a dozen differ-
ent kinds. These acids, as well as their acid
salts (i. e., in combination with potash, soda,
and ammonia), act energetically on carbonate
of lime and on the oxides of iron. It is, also,

Chap. V.

AND DENUDATION.

245

known that some of these acids, which were
called long ago by Thenard azohumic, are en-
abled to dissolve colloid silica in proportion
to the nitrogen which they contain.* In the
formation of these latter acids worms probably
afford some aid, for Dr. H. Johnson informs
me that by Nessler’s test he found 0.018 per
cent, of ammonia in their castings.

The several humus-acids, which appear, as
we have just seen, to be generated within the
bodies of worms during the digestive process,
and their acid salts, play a highly important
part, according to the recent observations of
Mr. Julien, in the disintegration of various
kinds of rocks. It has long been known that
the carbonic acid, and no doubt nitric and
nitrous acids, which are present in rain-water,
act in like manner. There is, also, a great ex-
cess of carbonic acid in all soils, especially in
rich soils, and this is dissolved by the water
in the ground. The living roots of plants,

* A. A. Julien “On the Geological Action of the Humus-
acids,” “Proc. American Assoc. Science,” vol. xxviii., 1879, p.
311. Also on “Chemical Erosion on Mountain Summits;”
“New York Academy of Sciences,” Oct. 14, 1878, as quoted in
the “American Naturalist.” See also, on this subject, S. W.
Johnson- “How Crops Feed,” 1870, p. 138.

246 DISINTEGRATION Chap. V.

moreover, as Sachs and others have shown,
quickly corrode and leave their impressions on
polished slabs of marble, dolomite and phos-
phate of lime. They will attack even basalt
and sandstone.* But we are not here con-
cerned with agencies which are wholly inde-
pendent of the action of worms.

The combination of any acid with a base
is much facilitated by agitation, as fresh sur-
faces are thus continually brought into con-
tact. This will be thoroughly effected with
the particles of stone and earth in the intes-
tines of worms, during the digestive process;
and it should be remembered that the entire
mass of the mould over every field, passes, in
the course of a few years, through their ali-
mentary canals. Moreover as the old burrows
slowly collapse, and as fresh castings are con-
tinually brought to the surface, the whole su-
perficial layer of mould slowly revolves or cir-
culates; and the friction of the particles one
with another will rub off the finest films of
disintegrated matter as soon as they are

* See for references on this subject, S. W. Johnson, “ Ilow
Crops Feed,” 1870, p. 326.

Chap. V.

AND DENUDATION.

247

formed. Through these several means, mi-
nute fragments of rocks of many kinds and
mere particles in the soil will be continually
exposed to chemical decomposition; and thus
the amount of soil will tend to increase.

As worms line their burrows with their
castings, and as the burrows penetrate to a
depth of 5 or 6, or even more feet, some small
amount of the humus-acids will be carried far
down, and will there act on the underlying
rocks and fragments of rock. Thus the thick-
ness of the soil, if none be removed from the
surface, will steadily though slowly tend to in-
crease; but the accumulation will after a time
delay the disintegration of the underlying
rocks and of the more deeply seated particles.
For the humus-acids which are generated
chiefly in the upper layer of vegetable mould,
are extremely unstable compounds, and are
liable to decomposition before they reach any
considerable depth.* A thick bed of overly-
ing soil will also check the downward exten-
sion of great fluctuations of temperature, and

* This statement is taken from Mr. Julien, “ Proc. American
Assoc. Science,1 ” vol. xxviii., 1879, P* 33°*

248

DISINTEGRATION

Chap. V.

in cold countries will check the powerful ac-
tion of frost. The free access of air will like-
wise be excluded. From these several causes
disintegration would be almost arrested, if the
overlying mould were to increase much in
thickness, owing to none or little being re-
moved from the surface.* In my own imme-
diate neighbourhood we have a curious proof
how effectually a few feet of clay checks some
change which goes on in flints, lying freely ex-
posed; for the large ones which have lain for
some time on the surface of ploughed fields
cannot be used for building; they will not
cleave properly and are said by the workmen
to be rotten. f It is therefore necessary to

* The preservative power of a layer of mould and turf is often
shown by the perfect state of the glacial scratches on rocks when
first uncovered. Mr. J. Geikie maintains, in his last very inter-
esting work (“ Prehistoric Europe,” 1881), that the more perfect
scratches are probably due to the last access of cold and increase
of ice, during the long-continued, intermittent glacial period.

f Many geologists have felt much surprise at the complete
disappearance of flints over wide and nearly level areas, from
which the chalk has been removed by subaerial denudation.
But the surface of every flint is coated by an opaque modified
layer, which will just yield to a steel point, whilst the freshly-
fractured, translucent surface will not thus yield. The removal
by atmospheric agencies of the outer modified surfaces of freely
exposed flints, though no doubt excessively slow, together with

Chap. V.

AND DENUDATION.

249

obtain flints for building purposes from the
bed of red clay overlying the chalk (the residue
of its dissolution by rainwater) or from the
chalk itself.

Not only do worms aid indirectly in the
chemical disintegration of rocks, but there is
good reason to believe that they likewise act
in a direct and mechanical manner on the
smaller particles. All the species which swal-
low earth are furnished with gizzards; and
these are lined with so thick a chitinous mem-
brane, that Perrier speaks of it * as “ une veri-
table armature.” The gizzard is surrounded
by powerful transverse muscles, which, ac-
cording to Claparede, are about ten times as
thick as the longitudinal ones; and Perrier saw
them contracting energetically. Worms be-
longing to one genus, Digaster, have two dis-
tinct but quite similar gizzards; and in an-
other genus, Moniligaster, the second gizzard
consists of four pouches, one succeeding the
other, so that it may almost be said to have

the modification travelling inwards, will, as may be suspected,
ultimately lead to their complete disintegration, notwithstanding
that they appear to be so extremely durable.

* “Archives de Zoolog. exper.,” tom. iii. 1874, p. 409.

250

DISINTEGRATION

Chap. V.

five gizzards.* In the same manner as galli-
naceous and struthious birds swallow stones to
aid in the trituration of their food, so it ap-
pears to be with terricolous worms. The giz-
zards of thirty-eight of our common worms
were opened, and in twenty-five of them small
stones or grains of sand, sometimes together
with the hard calcareous concretions formed
within the anterior calciferous glands, were
found, and in two others concretions alone.
In the gizzards of the remaining worms there
were no stones; but some of these were not
real exceptions, as the gizzards were opened
late in the autumn when the worms had
ceased to feed and their gizzards were quite
empty. f

When worms make their burrows through
earth abounding with little stones, no doubt
many will be unavoidably swallowed; but it
must not be supposed that this fact accounts
for the frequency with which stones and sand

* “ Nouvelles Archives du Museum/' tom. viii. 1872, pp. 95,
131.

f Morren, in speaking of the earth in the alimentary canals
of worms, says, “ praesep& cum lapillis commixtam vidi ; ” “ De
Lumbrici terrestris,” &c., 1829, p. 16.

Chap. V. AND DENUDATION. 251

are found in their gizzards. For beads of
glass and fragments of brick and of hard tiles
were scattered over the surface of the earth,
in pots in which worms were kept and had al-
ready made their burrows; and very many of
these beads and fragments were picked up and
swallowed by the worms, for they were found
in their castings, intestines, and gizzards. They
even swallowed the coarse red dust, formed
by the pounding of the tiles. Nor can it be
supposed that they mistook the beads and
fragments for food; for we have seen that
their taste is delicate enough to distinguish
between different kinds of leaves. It is there-
fore manifest that they swallow hard objects, j
such as bits of stone, beads of glass and angu-
lar fragments of bricks or tiles for some special
purpose; and it can hardly be doubted that
this is to aid their gizzards in crushing and
grinding the earth, which they so largely con-
sume. That such hard objects are not neces-
sary for crushing leaves, may be inferred from
the fact that certain species, which live in mud
or water and feed on dead or living vegetable
matter, but which do not swallow earth, are

252 DISINTEGRATION Chap. V.

not provided with gizzards,* and therefore
cannot have the power of utilising stones.

During the grinding process, the particles
of earth must be rubbed against one another,
and between the stones and the tough lining
membrane of the gizzard. The softer parti-
cles will thus suffer some attrition, and will
perhaps even be crushed. This conclusion is
supported by the appearance of freshly ejected
castings, for these often reminded me of the
appearance of paint which has just been
ground by a workman between two flat stones.
Morren remarks that the intestinal canal is
“ impleta tenuissima terra, veluti in pulverem
redacta.” f Perrier also speaks of “ l’etat de
pate excessivement fine a laquelle est reduite
la terre qu’ils rejettent,” &c. X

As the amount of trituration which the
particles of earth undergo in the gizzards of
worms possesses some interest (as we shall
hereafter see), I endeavoured to obtain evi-
dence on this head by carefully examining

* Perrier, “ Archives de Zoolog. exper.,” tom. iii. 1874,
p. 419.

f Morren, u De Lumbrici terrestris,” &c., p. 16.

X “ Archives de Zoolog. exper.,” tom. iii. 1874, P* 418.

Chap. V.

AND DENUDATION.

253

many of the fragments which had passed
through their alimentary canals. With worms
living in a state of nature, it is of course impos-
sible to know how much the fragments may
have been worn before they were swallowed.
It is, however, clear that worms do not habitu-
ally select already rounded particles, for sharply
angular bits of flint and of other hard rocks
were often found in their gizzards or intestines.
On three occasions sharp spines from the stems
of rose-bushes were thus found. Worms kept
in confinement repeatedly swallowed angular
fragments of hard tile, coal, cinders, and even
the sharpest fragments of glass. Gallinaceous
and struthious birds retain the same stones in
their gizzards for a long time, which thus be-
come well rounded; but this does not appear
to be the case with worms, judging from the
large number of the fragments of tiles, glass
beads, stones, &c., commonly found in their
castings and intestines. So that unless the
same fragments were to pass repeatedly
through their gizzards, visible signs of attri-
tion in the fragments could hardly be expected,
except perhaps in the case of very soft stones.

254 DISINTEGRATION Chap. V.

I will now give such evidence of attrition
as I have been able to collect. In the gizzards
of some worms dug out of a thin bed of mould
over the chalk, there were many well-rounded
small fragments of chalk, and two fragments
of the shells of a land mollusc (as ascertained
by their microscopical structure), which latter
were not only rounded but somewhat polished.
The calcareous concretions formed in the cal-
ciferous glands, which are often found in their
gizzards, intestines, and occasionally in their
castings, when of large size, sometimes ap-
peared to have been rounded; but with all cal-
careous bodies the rounded appearance may be
partly or wholly due to their corrosion by car-
bonic acid and the humus-acids. In the giz-
zards of several worms collected in my kitchen
garden near a hothouse, eight little fragments
of cinders were found, and of these, six ap-
peared more or less rounded, as were two bits
of brick; and some other bits were not at all
rounded. A farm-road near Abinger Hall
had been covered seven years before with
brick-rubbish to the depth of about 6 inches;
turf had grown over this rubbish on both sides

Chap. V.

AND DENUDATION.

255

of the road for a width of 18 inches, and on
this turf there were innumerable castings.
Some of them were coloured of a uniform red
owing to the presence of much brick-dust, and
they contained many particles of brick and of
hard mortar from 1 to 3 mm. in diameter, most
of which were plainly rounded; but all these
particles may have been rounded before they
were protected by the turf and were swallowed,
like those on the bare parts of the road which
were much worn. A hole in a pasture-field
had been filled up with brick-rubbish at the
same time, viz., seven years ago, and was now
covered with turf; and here the castings con-
tained very many particles of brick, all more or
less rounded; and this brick-rubbish, after be-
ing shot into the hole, could not have under-
gone any attrition. Again, old bricks very
little broken, together with fragments of mor-
tar, were laid down to form walks, and were
then covered with from 4 to 6 inches of gravel;
six little fragments of brick were extracted
from castings collected on these walks, three
of which were plainly worn. There were also
very many particles of hard mortar, about half

256 DISINTEGRATION Chap. V.

of which were well rounded; and it is not cred-
ible that these could have suffered so much
corrosion from the action of carbonic acid in
the course of only seven years.

Much better evidence of the attrition of
hard objects in the gizzards of worms, is af-
forded by the state of the small fragments of
tiles or bricks, and of concrete in the castings
thrown up where ancient buildings once stood.
As all the mould covering a field passes every
few years through the bodies of worms, the
same small fragments will probably be swal-
lowed and brought to the surface many times
in the course of centuries. It should be prem-
ised that in the several following cases, the
final matter was first washed away from the
castings, and then all the particles of bricks,
tiles and concrete were collected without any
selection, and were afterwards examined.
Now in the castings ejected between the tes-
serae on one of the buried floors of the Roman
villa at Abinger, there were many particles
(from | to 2 mm. in diameter) of tiles and
concrete, which it was impossible to look at
with the naked eye or through a strong lens,

Chap. V.

AND DENUDATION.

257

and doubt for a moment that they had almost
all undergone much attrition. I speak thus
after having examined small water-worn peb-
bles, formed from Roman bricks, which M.
Henri de Saussure had the kindness to send
me, and which he had extracted from sand and
gravel beds, deposited on the shores of the
Lake of Geneva, at a former period when the
water stood at about two metres above its
present level. The smallest of these water-
worn pebbles of brick from Geneva resembled
closely many of those extracted from the giz-
zards of worms, but the larger ones were some-
what smoother.

Four castings found on the recently un-
covered, tessellated floor of the great room in
the Roman villa at Brading, contained many
particles of tile or brick, of mortar, and of
hard white cement; and the majority of these
appeared plainly worn. The particles of mor-
tar, however, seemed to have suffered more
corrosion than attrition, for grains of silex
often projected from their surfaces. Castings
from within the nave of Beaulieu Abbey, which
was destroyed by Henry VIII., were collected

258

DISINTEGRATION

Chap. V.

from a level expanse of turf, overlying the
buried tessellated pavement, through which
worm-burrows passed; and these castings con-
tained innumerable particles of tiles and bricks,
of concrete and cement, the majority of which
had manifestly undergone some or much attri-
tion. There were also many minute flakes of
a micaceous slate, the points of which were
rounded. If the above supposition, that in all
these cases the same minute fragments have
passed several times through the gizzards of
worms, be rejected, notwithstanding its in-
herent probability, we must then assume that
in all the above cases the many rounded
fragments found in the castings had all ac-
cidentally undergone much attrition before
they were swallowed; and this is highly im-
probable.

On the other hand it must be stated that
fragments of ornamental tiles, somewhat
harder than common tiles or bricks, which had
been swallowed only once by worms kept in
confinement, were with the doubtful exception
of one or two of the smallest grains, not at all
rounded. Nevertheless some of them ap-

Chap. V.

AND DENUDATION.

259

peared a little worn, though not rounded.
Notwithstanding these cases, if we consider
the evidence above given, there can be little
doubt that the fragments, which serve as mill-
stones in the gizzards of worms, suffer, when
of a not very hard texture, some amount of
attrition; and that the smaller particles in the
earth, which is habitually swallowed in such
astonishingly large quantities by worms, are
ground together and are thus levigated. If
this be the case, the “ terra tenuissima,” — the
“ pate excessivement fine,” — of which the cast-
ings largely consist, is in part due to the me-
chanical action of the gizzard; * and this fine
matter, as we shall see in the next chapter,
is that which is chiefly washed away from
the innumerable castings on every field dur-
ing each heavy shower of rain. If the
softer stones yield at all, the harder ones

* This conclusion reminds me of the vast amount of extremely
fine chalky mud which is found within the lagoons of many
atolls, where the sea is tranquil and waves cannot triturate the
blocks of coral. This mud must, as I believe (“ The Structure
and Distribution of Coral-Reefs,” 2nd edit. 1874, p. 19), be at-
tributed to the innumerable annelids and other animals which
burrow into the dead coral, and to the fishes, Holothurians, &c.,
which browse on the living corals.

26o

DISINTEGRATION

Chap. V.

will suffer some slight amount of wear and
tear.

The trituration of small particles of stone
in the gizzards of worms is of more importance
under a geological point of view than may at
first appear to be the case; for Mr. Sorby has
clearly shown that the ordinary means of dis-
integration, namely running water and the
waves of the sea, act with less and less power
on fragments of rock the smaller they are.
“ Hence,” as he remarks, “ even making no al-
lowance for the extra buoying up of very
minute particles by a current of water, depend-
ing on surface cohesion, the effects of wearing
on the form of the grains must vary directly
as their diameter or thereabouts. If so, a
grain of an inch in diameter would be worn
ten times as much as one -ygy of an inch in
diameter, and at least a hundred times as much
as one y-gVg of an inch in diameter. Perhaps,
then, we may conclude that a grain yg- of an
inch in diameter would be worn as much or
more in drifting a mile as a grain Ttnru of an
inch in being drifted ioo miles. On the same
principle a pebble one inch in diameter would

Chap. V.

AND DENUDATION.

26l

be worn relatively more by being drifted only
a few hundred yards.” * Nor should we for-
get, in considering the power which worms
exert in triturating particles of rock, that there
is good evidence that on each acre of land,
which is sufficiently damp and not too sandy,
gravelly or rocky for worms to inhabit, a
weight of more than ten tons of earth annu-
ally passes through their bodies and is brought
to the surface. The result for a country of the
size of Great Britain, within a period not very
long in a geological sense, such as a million
years, cannot be insignificant; for the ten tons
of earth has to be multiplied first by the above
number of years, and then by the number of
acres fully stocked with worms; and in Eng-
land, together with Scotland, the land which
is cultivated and is well fitted for these animals,
has been estimated at above 32 million acres.
The product is 320 million million tons of
earth.

* Anniversary Address: “The Quarterly Journal of the
Geological Soc.,” May, 1880, p. 59.

CHAPTER VI.

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 com-
pletely away from castings — The disintegration of dried cast-
ings 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 blowp 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.

We are now prepared to consider the more
direct part which worms take in the denuda-
tion of the land. When reflecting on subaerial
denudation, it formerly appeared to me, as it
has to others, that a nearly level or very gently
inclined surface, covered with turf, could suffer
no loss during even a long lapse of time. It
may, however, be urged that at long intervals,

debacles of rain or water-spouts would remove

262

Chap. VI.

AIDED BY WORMS.

263

all the mould from a very gentle slope; but
when examining the steep, turf-covered slopes
in Glen Roy, I was struck with the fact how
rarely any such event could have happened
since the Glacial period, as was plain from the
well-preserved state of the three successive
“ roads ” or lake-margins. But the difficulty
in believing that earth in any appreciable quan-
tity can be removed from a gently inclined sur-
face, covered with vegetation and matted with
roots, is removed through the agency of
worms. For the many castings which are
thrown up during rain, and those thrown up
some little time before heavy rain, flow for a
short distance down an inclined surface.
Moreover much of the finest levigated earth
is washed completely away from the castings.
During dry weather castings often disintegrate
into small rounded pellets, and these from their
weight often roll down any slope. This is
more especially apt to occur when they are
started by the wind, and probably when started
by the touch of an animal, however small.
We shall also see that a strong wind blows all
the castings, even on a level field, to leeward,

264

DENUDATION OF THE LAND Chap. VI.

whilst they are soft; and in like manner the
pellets when they are dry. If the wind blows
in nearly the direction of an inclined surface,
the flowing down of the castings is much aided.

The observations on which these several
statements are founded must now be given in
some detail. Castings when first ejected are
^viscid and soft; during rain, at which time
worms apparently prefer to eject them, they ,
are still softer; so that I have sometimes
thought that worms must swallow much water
at such times. .However this may be, rain,
even when not very heavy, if long continued,
renders recently-ejected castings semi-fluid;
and on level ground they then spread out into
thin, circular, flat discs, exactly as would so
much honey or very soft mortar, with all traces
of their vermiform structure lost. This latter
fact was sometimes made evident, when a
worm had subsequently bored through a flat
circular disc of this kind, and heaped up a
fresh vermiform mass in the centre. These
flat subsided discs have been repeatedly seen
by me after heavy rain, in many places on land
of all kinds.

Chap. VI.

AIDED BY WORMS.

265

On the flowing of wet castings , and the roll-
ing of dry disintegrated castings down inclined
surfaces . — When castings are ejected on an in-
clined surface during or shortly before heavy
rain, they cannot fail to flow a little down the
slope. Thus, on some steep slopes in Knowle
Park, which were covered with coarse grass
and had apparently existed in this state from
time immemorial, I found (Oct. 22, 1872) after
several wet days that almost all the many cast-
ings were considerably elongated in the line
of the slope; and that they now consisted of
smooth, only slightly conical masses. When-
ever the mouths of the burrows could be found
from which the earth had been ejected, there
was more earth below than above them. After
some heavy storms of rain (Jan. 25, 1872) two
rather steeply inclined fields near Down, which
had formerly been ploughed and were now
rather sparsely clothed with poor grass, were
visited, and many castings extended down the
slopes for a length of 5 inches, which was twice
or thrice the usual diameter of the castings
thrown up on the level parts of these same

fields. On some fine grassy slopes in Hol-

18

266

DENUDATION OF THE LAND Chap. VI.

wood Park, inclined at angles between 8° and
n° 30' with the horizon, where the surface ap-
parently had never been disturbed by the hand
of man, castings abounded in extraordinary
numbers; and a space 16 inches in length trans-
versely to the slope and 6 inches in the line of
the slope, was completely coated, between the
blades of grass, with a uniform sheet of con-
fluent and subsided castings. Here also in
many places the castings had flowed down the
slope, and now formed smooth narrow patches
of earth, 6, 7, and inches in length. Some
of these consisted of two castings, one above
the other, which had become so completely
confluent that they could hardly be distin-
guished. On my lawn, clothed with very fine
grass, most of the castings are black, but some
are yellowish from earth having been brought
up from a greater depth than usual, and the
flowing-down of these yellow castings after
heavy rain, could be clearly seen where the
slope was 50; and where it was less than i°
some evidence of their flowing-down could
still be detected. On another occasion, after
rain which was never heavy, but which lasted

Chap. VI.

AIDED BY WORMS.

267

for 18 hours, all the castings on this same
gently inclined lawn had lost their vermifoi

structure; and they had flowed, so that fully
two-thirds of the ejected earth lay below the
mouths of the burrows.

These observations led me to make others
with more care. Eight castings were found
on my lawn, where the grass-blades are fine
and close together, and three others on a field
with coarse grass. The inclination of the sur-
face at the eleven places where these castings
were collected varied between 40 30' and 170
30'; the mean of the eleven inclinations being
90 26'. The length of the castings in the di-
rection of the slope was first measured with as
much accuracy as their irregularities would
permit. It was found possible to make these
measurements within about -J of an inch, but
one of the castings was too irregular to admit
of measurement. The average length in the
direction of the slope of the remaining ten
castings was 2.03 inches. The castings were
then divided with a knife into two parts along
a horizontal line passing through the mouth
of the burrow, which was discovered by slicing

268

DENUDATION OF THE LAND Chap. VI.

off the turf; and all the ejected earth was sepa-
rately collected, namely the part above the hole
and the part below. Afterwards these two
parts were weighed. In every case there was
much more earth below than above; the mean
weight of that above being 103 grains, and of
that below 205 grains; so that the latter was
very nearly double the former. As on level
ground castings are commonly thrown up al-
most equally round the mouths of the burrows,
this difference in weight indicates the amount
of ejected earth which had flowed down the
slope. But very many more observations
would be requisite to arrive at any general
result; for the nature of the vegetation and
other accidental circumstances, such as the
heaviness of the rain, the direction and force
of the wind, &c., appear to be more impor-
tant in determining the quantity of the earth
which flows down a slope than its angle.
Thus with four castings on my lawn (in-
cluded in the above eleven) where the mean
slope was 70 19', the difference in the
amount of earth above and below the bur-
rows was greater than with three other cast-

Chap. VI. AIDED BY WORMS. 269

ings on the same lawn where the mean slope
was 120 5'.

We may, however, take the above eleven
cases, which are accurate as far as they go,
and calculate the weight of the ejected earth
which annually flows down a slope having a
mean inclination of 90 26'. This was done
by my son George. It has been shown that
almost exactly two-thirds of the ejected earth
is found below the mouth of the burrow and
one-third above it. Now if the two-thirds
which is below the hole be divided into two
equal parts, the upper half of this two-thirds
exactly counterbalances the one-third which is
above the hole, so that as far as regards the
one-third above and the upper half of the two-
thirds below, there is no flow of earth down
the hill-side. The earth constituting the lower
half of the two-thirds is, however, displaced
through distances which are different for
every part of it, but which may be represented
by the distance between the middle point of
the lower half of the two-thirds and the hole.
So that the average distance of displacement
is a half of the whole length of the worm-cast-

27 o

DENUDATION OF THE LAND Chap. VI.

ing. Now the average length of ten out of
the above eleven castings was 2.03 inches, and
half of this we may take as being one inch.
It may therefore be concluded that one-third
of the whole earth brought to the surface was
in these cases carried down the slope through
one inch.

It was shown in the third chapter that on
Leith Hill Common, dry earth weighing at
least 7.453 lbs. was brought up by worms to
the surface on a square yard in the course of a
year. If a square yard be drawn on a hill-side
with two of its sides horizontal, then it is clear
that only part of the earth brought up on
that square yard would be near enough to its
lower side to cross it, supposing the displace-
ment of the earth to be through one inch.
But it appears that only J of the earth brought
up can be considered to flow downwards;
hence g of -^V or of 7.453 lbs. will cross the
lower side of our square yard in a year. Now
T-g-g- of 7.453 lbs. is 1. 1 oz. Therefore 1.1 oz.
of dry earth will annually cross each linear
yard running horizontally along a slope having
the above inclination; or very nearly 7 lbs.

Chap. VI.

AIDED BY WORMS.

271

will annually cross a horizontal line, 100 yards
in length, on a hill-side having this inclination.

A more accurate, though still very rough,
calculation can be made of the bulk of earth,
which in its natural damp state annually flows
down the same slope over a yard-line drawn
horizontally across it. From the several cases
given in the third chapter, it is known that the
castings annually brought to the surface on
a square yard, if uniformly spread out would
form a layer .2 of an inch in thickness: it there-
fore follows by a calculation similar to the one
already given, that ^ of .2 X 36, or 2.4 cubic
inches of damp earth will annually cross a hori-
zontal line one yard in length on a hill-side
with the above inclination. This bulk of damp
castings was found to weigh 1.85 oz. There-
fore 11.56 lbs. of damp earth, instead of 7 lbs.
of dry earth as by the former calculation, would
annually cross a line 100 yards in length on
our inclined surface.

In these calculations it has been assumed
that the castings flow a short distance down-
wards during the whole year, but this occurs
only with those ejected during or shortly be-

272 DENUDATION OF THE LAND Chap. VI.

fore rain; so that the above results are thus
far exaggerated. On the other hand, during
rain much of the finest earth is washed to a
considerable distance from the castings, even
where the slope is an extremely gentle one,
and is thus wholly lost as far as the above
calculations are concerned. Castings ejected
during dry weather and which have set hard,
lose in the same manner a considerable quan-
tity of fine earth. Dried castings, moreover,
are apt to disintegrate into little pellets, which
often roll or are blown down any inclined sur-
face. Therefore the above result, namely that
2.4 cubic inches of earth (weighing 1.85 oz.
whilst damp) annually crosses a yard-line of
*■’ the specified kind, is probably not much if at all
exaggerated.

This amount is small; but we should bear
in mind how many brainching valleys inter-
sect most countries, the whole length of which
must be very great; and that earth is steadily
travelling down both turf-covered sides of each
valley. For every 100 yards in length in a
valley with sides sloping as in the foregoing
cases, 480 cubic inches of damp earth, weigh-

Chap. VI.

AIDED BY WORMS.

273

in g above 23 pounds, will annually reach the
bottom. Here a thick bed of alluvium will
accumulate, ready to be washed away in the
course of centuries, as the stream in the middle
meanders from side to side.

If it could be shown that worms generally
excavate their burrows at right angles to an
inclined surface, and this would be their short-
est course for bringing up earth from beneath,
then as the old burrows collapsed from the
weight of the superincumbent soil, the collaps-
ing would inevitably cause the whole bed of
vegetable mould to sink or slide slowly down
the inclined surface. But to ascertain the di-
rection of many burrows was found too diffi-
cult and troublesome. A straight piece of
wire was, however, pushed into twenty-five
burrows on several sloping fields, and in eight
cases the burrows were nearly at right angles
to the slope; whilst in the remaining cases they
were indifferently directed at various angles,
either upwards or downwards with respect to
the slope.

In countries where the rain is very heavy,
as in the tropics, the castings appear, as might

274

DENUDATION OF THE LAND Chap. VI.

have been expected, to be washed down in a
greater degree than in England. Mr. Scott
informs me that near Calcutta the tall colum-
nar castings (previously described), the diam-
eter of which is usually between I and i-J inch,
subside on a level surface, after heavy rain,
into almost circular, thin, flat discs, between 3
and 4 and sometimes 5 inches in diameter.
Three fresh castings, which had been ejected
in the Botanic Gardens “ on a slightly inclined,
grass-covered, artificial bank of loamy clay,”
were carefully measured, and had a mean
height of 2.17, and a mean diameter of 1.43
inches; these after heavy rain, formed elon-
gated patches of earth, with a mean length in
the direction of the slope of 5.83 inches. As
the earth had spread very little up the slope,
a large part, judging from the original diam-
eter of these castings, must have flowed bodily
downwards about 4 inches. Moreover some
of the finest earth of which they were com-
posed must have been washed completely away
to a still greater distance. In drier sites near
Calcutta, a species of worm ejects its castings,
not in vermiform masses, but in little pellets

Chap. VI.

AIDED BY WORMS.

275

of varying sizes: these are very numerous in
some places, and Mr. Scott says that they “ are
washed away by every shower.”

I was led to believe that a considerable
quantity of fine earth is washed quite away
from castings during rain, from the surfaces
of old ones being often studded with coarse
particles. Accordingly a little fine precipitated
chalk, moistened with saliva or gum-water, so
as to be slightly viscid and of the same con-
sistence as a fresh casting, was placed on the
summits of several castings and gently mixed
with them. These castings were then watered
through a very fine rose, the drops from which
were closer together than those of rain, but
not nearly so large as those in a thunder storm;
nor did they strike the ground with nearly so
much force as drops during heavy rain. A
casting thus treated subsided with surprising
slowness, owing as I suppose to its viscidity.
It did not flow bodily down the {

at an angle of 160 20'; nevertheless many par-
ticles of the chalk were found three inches bel-
low the casting. The experiment was repeated

surface of the lawn, which was

276 DENUDATION OF THE LAND Chap. VI.

on three other castings on different parts of
the lawn, which sloped at 20 30', 30 and 6°;
and particles of chalk could be seen between
4 and 5 inches below the casting; and after
the surface had become dry, particles were
found in two cases at a distance of 5 and 6
inches. Several other castings with precipi-
tated chalk placed on their summits were left
to the natural action of the rain. In one case,
after rain which was not heavy, the casting
was longitudinally streaked with white. In
two other cases the surface of the ground was
rendered somewhat white for a distance of
one inch from the casting; and some soil col-
lected at a distance of 2\ inches, where the
slope was 70, effervesced slightly when placed
in acid. After one or two weeks, the chalk
was wholly or almost wholly washed away
from all the castings on which it had been
placed, and these had recovered their natural
colour.

It may be here remarked that after very
heavy rain shallow pools may be seen on level
or nearly level fields, where the soil is not very
porous, and the water in them is often slightly

Chap. VI.

AIDED BY WORMS.

2 77

muddy; when such little pools have dried, the
leaves and blades of grass at their bottoms are
generally coated with a thin layer of mud.
This mud I believe is derived in large part
from recently ejected castings.

Dr. King informs me that the majority of
the before described gigantic castings, which
he found on a fully exposed, bare, gravelly
knoll on the Nilgiri Mountains in India, had
been more or less weathered by the previous
north-east monsoon; and most of them pre-
sented a subsided appearance. The worms
here eject their castings only during the rainy
season; and at the time of Dr. King's visit no
rain had fallen for no days. He carefully ex-
amined the ground between the place where
these huge castings lay, and a little water-
course at the base of the knoll, and nowhere
was there any accumulation of fine earth, such
as would necessarily have been left by the dis-
integration of the castings if they had not been
wholly removed. He therefore has no hesita-
tion in asserting that the whole of these huge
castings are annually washed during the two
monsoons (when about 100 inches of rain fall)

«/

2 78 DENUDATION OF THE LAND Chap. VI.

into the little water-course, and thence into the
plains lying below at a depth of 3000 or 4000
feet.

Castings ejected before or during dry
Weather become hard, sometimes surprisingly
hard, from the particles of earth having been
cemented together by the intestinal secretions.
Frost seems to be less effective in their disin-
tegration than might have been expected.
Nevertheless they readily disintegrate into
small pellets, after being alternately moistened
with rain and again dried. Those which have
flowed during rain down a slope, disintegrate
in the same manner. Such pellets often roll a
little down any sloping surface; their descent
being sometimes much aided by the wind.
The whole bottom of a broad dry ditch in my
grounds, where there were very few fresh cast-
ings, was completely covered with these pellets
or disintegrated castings, which had rolled
down the steep sides inclined at an angle
of 270.

Near Nice, in places where the great cylin-
drical castings, previously described, abound,
the soil consists of very fine arenaceo-calcare-

Chap. VI.

AIDED BY WORMS.

279

ous loam; and Dr. King informs me that these
castings are extremely liable to crumble during
dry weather into small fragments, which are
soon acted on by rain, and then sink down so
as to be no longer distinguishable from the
surrounding soil. He sent me a mass of such
disintegrated castings, collected on the top of
a bank, where none could have rolled dowrt
from above. They must have been ejected
within the previous five or six months, but
they now consisted of more or less rounded
fragments of all sizes, from f of an inch in
diameter to minute grains and mere dust. Dr.
King witnessed the crumbling process whilst
drying some perfect castings, which he after-
wards sent me. Mr. Scott also remarks on the
crumbling of the castings near Calcutta and on
the mountains of Sikkim during the hot and
dry season.

When the castings near Nice had been
ejected on an inclined surface, the disinte-
grated fragments rolled downwards, without
losing their distinctive shape; and in some
places could “ be collected in basketfuls.” Dr.
King observed a striking instance of this fact

280

DENUDATION TO LAND

Chap. VI.

on the Corniche road, where a drain, about
2.\ feet wide and 9 inches deep, had been made
to catch the surface drainings from the adjoin-
ing hill-side. The bottom of this drain was
covered for a distance of several hundred yards,
to a depth of from i| to 3 inches, by a layer
of broken castings, still retaining their charac-
teristic shape. Nearly all these innumerable
fragments had rolled down from above, for ex-
tremely few castings had been ejected in the
drain itself. The hill-side was steep, but varied
much in inclination, which Dr. King estimated
at from 30° to 6o° with the horizon. He
climbed up the slope, and “ found every here
and there little embankments, formed by frag-
ments of the castings that had been arrested
in their downward progress by irregularities of
the surface, by stones, twigs, &c. One little
group of plants of Anemone hortensis had acted
in this manner, and quite a small bank of soil
had collected round it. Much of this soil had
crumbled down, but a great deal of it still re-
tained the form of castings.” Dr. King dug
up this plant, and was struck with the thick-
ness of the soil which must have recently accu-

Chap. VI.

LEDGES ON HILL-SIDES.

28l

mulated over the crown of the rhizoma, as
shown by the length of the bleached petioles,
in comparison with those of other plants of
the same kind, where there had been no such
accumulation. The earth thus accumulated
had no doubt been secured (as I have every-
where seen) by the smaller roots of the plants.
After describing this and other analogous
cases, Dr. King concludes: “ I can have no
doubt that worms help greatly in the process
of denudation.”

Ledges of earth on steep hill-sides. — Little
horizontal ledges, one above another, have
been observed on steep grassy slopes in many
parts of the world. Their formation has been
attributed to animals travelling repeatedly
along the slope in the same horizontal lines
while grazing, and that they do thus move and
use the ledges is certain; but Professor Hens-
low (a most careful observer) told Sir J. Hook-
er that he was convinced that this was not the
sole cause of their formation. Sir J. Hooker
saw such ledges on the Himalayan and Atlas
ranges, where there were no domesticated ani-
mals and not many wild ones; but these latter
19

282

DENUDATION TO LAND

Chap. VI.

would, it is probable, use the ledges at night
while grazing like our domesticated animals.
A friend observed for me the ledges on the
Alps of Switzerland, and states that they ran
at 3 or 4 feet one above the other and were
about a foot in breadth. They had been deep-
ly pitted by the feet of grazing cows. Similar
ledges were observed by the same friend on
our Chalk downs, and on an old talus of chalk-
fragments (thrown out of a quarry) which had
become clothed with turf.

My son Francis examined a Chalk escarp-
ment near Lewes; and here on a part which
was very steep, sloping at 40° with the hori-
zon, about 30 flat ledges extended horizontally
for more than 100 yards, at an average distance
of about 20 inches, one beneath the other.
They were from 9 to 10 inches in breadth.
When viewed from a distance they presented a
striking appearance, owing to their parallel-
ism; but when examined closely, they were
seen to be somewhat sinuous, and one often
ran into another, giving the appearance of one
ledge having forked into two. They are
formed of light-coloured earth, which on the

Chap. VI.

LEDGES ON HILL-SIDES.

283

outside, where thickest, was in one case 9
inches, and in another case between 6 and 7
inches in thickness. Above the ledges, the
thickness of the earth over the chalk was in
the former case 4 and in the latter only 3
inches. The grass grew more vigorously on
the outer edges of the ledges than on any
other part of the slope, and here formed a
tufted fringe. Their middle part was bare, but
whether this had been caused by the trampling
of sheep, which sometimes frequent the ledges,
my son could not ascertain. Nor could he
feel sure how much of the earth on the middle
and bare parts, consisted of disintegrated
worm-castings which had rolled down from
above; but he felt convinced that some had
thus originated; and it was manifest that the
ledges with their grass-fringed edges would
arrest any small object rolling down from
above.

^At one end or side of the bank bearing
these ledges, the surface consisted in parts of
bare chalk, and here the ledges were very ir-
regular. At the other end of the bank, the
slope suddenly became less steep, and here the

284 DENUDATION TO LAND Chap. VI.

ledges ceased rather abruptly; but little em-
bankments only a foot or two in length were
still present. The slope became steeper lower
down the hill, and the regular ledges then re-
appeared. Another of my sons observed, on
the inland side of Beachy Head, where the
surface sloped at about 250, many short little
embankments like those just mentioned. They
extended horizontally and were from a few
inches to two or three feet in length. They
supported tufts of grass growing vigorously.
The average thickness of the mould of which
they were formed, taken from nine measure-
ments, was 4.5 inches; while that of the mould
above and beneath them was on an average
only 3.2 inches, and on each side, on the same
level, 3.1 inches. On the upper parts of the
slope, these embankments showed no signs of
having been trampled on by sheep, but in the
lower parts such signs were fairly plain. No
long continuous ledges had here been formed.

If the little embankments above the Cor-
niche road, which Dr. King saw in the act of
formation by the accumulation of disintegrated
and rolled worm-castings, were to become con-

Chap. VI. LEDGES ON HILL-SIDES. 285

fluent along horizontal lines, ledges would be
formed. Each embankment would tend to ex-
tend laterally by the lateral extension of the
arrested castings; and animals grazing on a
steep slope would almost certainly make use
of every prominence at nearly the same level,
and would indent the turf between them; and
such intermediate indentations would again
arrest the castings. An irregular ledge when
once formed would also tend to become more
regular and horizontal by some of the castings
rolling laterally from the higher to the lower
parts, which would thus be raised. Any pro-
jection beneath a ledge would not afterwards
receive disintegrated matter from above, and
would tend to be obliterated by rain and other
atmospheric agencies. There is some analogy
between the formation, as here supposed, of
these ledges, and that of the ripples of wind-
drifted sand as described by Lyell.*

The steep, grass-covered sides of a moun-
tainous valley in Westmoreland, called Grise-
dale, was marked in many places with innumer-
able, almost horizontal, little ledges, or rather

* “Elements of Geology,” 1865, p. 20.

286

DENUDATION OF THE LAND. Chap. VI.

lines of miniature cliffs. Their formation was
in no way connected with the action of worms,
for castings could not anywhere be seen (and
their absence is an inexplicable fact) although
the turf lay in many places over a considerable
thickness of boulder-clay and moraine rubbish.
Nor, as far as I can judge, was the formation
of these little cliffs at all closely connected
with the trampling of cows or sheep. It ap-
peared as if the whole superficial, somewhat
argillaceous earth, while partially held together
by the roots of the grasses, had slided a little
way down the mountain sides; and in thus
sliding, had yielded and cracked in horizontal
lines, transversely to the slope.

Castings blown to leeward by the wind . — We
have seen that moist castings flow, and that
disintegrated castings roll down any inclined
surface; and we shall now see that castings,
recently ejected on level grass-covered sur-
faces, are blown during gales of wind accom-
panied by rain to leeward. This has been ob-
served by me many times on many fields
during several successive years. After such

Chap. VI. CASTINGS BLOWN TO LEEWARD. 287

gales, the castings present a gently inclined
and smooth, or sometimes furrowed, surface
to windward, while they are steeply inclined
or precipitous to leeward, so that they resem-
ble on a miniature scale glacier-ground hillocks
of rock. They are often cavernous on the lee-
ward side, from the upper part having curled
over the lower part. During one unusually
heavy south-west gale with torrents of rain,
many castings were wholly blown to leeward,
so that the mouths of the burrows were left
naked and exposed on the windward side. Re-
cent castings naturally flow down an inclined
surface, but on a grassy field, which sloped be-
tween io° and 1 50, several were found after a
heavy gale blown up the slope. This like-
wise occurred on another occasion on a part
of my lawn where the slope was somewhat less.
On a third occasion, the castings on the steep,
grass-covered sides of a valley, down which a
gale had blown, were directed obliquely in-
stead of straight down the slope; and this was
obviously due to the combined action of the
wind and gravity. Four castings on my lawn,
where the downward inclination was o° 45', i°,

288

DENUDATION OF THE LAND. Chap. VI.

3° and 30 30' (mean 2° 45') towards the north-
east, after a heavy south-west gale with rain,
were divided across the mouths of the bur-
rows and weighed in the manner formerly de-
scribed. The mean weight of the earth below
the mouths of burrows and to leeward, was to
that above the mouths and on the windward
side as 2§ to 1; whereas we have seen that
with several castings which had flowed down
slopes having a mean inclination of 90 26', and
with three castings where the inclination was
above 120, the proportional weight of the
earth below to that above the burrows was as
only 2 to 1. These several cases show how
efficiently gales of wind accompanied by rain
act in displacing recently-ejected castings.
-We may therefore conclude that even a mod-
erately strong wind will produce some slight
effect on them.

Dry and indurated castings, after their dis-
integration into small fragments or pellets, are
sometimes, probably often, blown by a strong
wind to leeward. This was observed on four
occasions, but I did not sufficiently attend to
this point. One old casting on a gently slop-

Chap. VI. CASTINGS BLOWN TO LEEWARD. 289

in g bank was blown quite away by a strong
south-west wind. Dr. King believes that the
wind removes the greater part of the old crum-
bling castings near Nice. Several old castings
on my lawn were marked with pins and pro-
tected from any disturbance. They were ex-
amined after an interval of 10 weeks, during
which time the weather had been alternately
dry and rainy. Some, which were of a yel-
lowish colour had been washed almost com-
pletely away, as could be seen by the colour
of the surrounding ground. Others had com-
pletely disappeared, and these no doubt had
been blown away. Lastly, others still re-
mained and would long remain, as blades of
grass had grown through them. On poor
pasture-land, which has never been rolled and
has not been much trampled on by animals, the
whole surface is sometimes dotted with little
pimples, through and on which grass grows;
and these pimples consist of old worm-castings.

In all the many observed cases of soft cast-
ings blown to leeward, this had been effected
by strong winds accompanied by rain. As
such winds in England generally blow from

290

DENUDATION OF THE LAND. Chap. VI.

the south and south-west, earth must on the
whole tend to travel over our fields in a north
and north-east direction. This fact is inter-
esting, because it might be thought that none
could be removed from a level, grass-covered
surface by any means. In thick and level
woods, protected from the wind, castings will
never be removed as long as the wood lasts;
and mould will here tend to accumulate to the
depth at which worms can work. I tried to
procure evidence as to how much mould is
blown, whilst in the state of castings, by our
wet southern gales to the north-east, over
open and flat land, by looking to the level o£
the surface on opposite sides of old trees and
hedge-rows; but I failed owing to the unequal
growth of the roots of trees and to most pas-
ture-land having been formerly ploughed.

On an open plain near Stonehenge, there
exist shallow circular trenches, with a low em-
bankment outside, surrounding level spaces 50
yards in diameter. These rings appear very
ancient, and are believed to be contempora-
neous with the Druidical stones. Castings
ejected within these circular spaces, if blown

Chap. VI. CASTINGS BLOWN TO LEEWARD. 2gi

to the north-east by south-west winds would
form a layer of mould within the trench thicker
on the north-eastern than on any other side.
But the site was not favourable for the action
of worms, for the mould over the surrounding
Chalk formation with flints, was only 3.37
inches in thickness, from a mean of six ob-
servations made at a distance of 10 yards out-
side the embankment. The thickness of the
mould within two of the circular trenches was
measured every 5 yards all round, on the inner
sides near the bottom. My son Horace pro-
tracted these measurements on paper; and
though the curved line representing the thick-
ness of the mould was extremely irregular, yet
in both diagrams it could be seen to be thicker
on the north-eastern side than elsewhere.
When a mean of all the measurements in both
the trenches was laid down and the line
smoothed, it was obvious that the mould was
thickest in the quarter of the circle between
north-west and north-east; and thinnest in the
quarter between south-east and south-west, es-
pecially at this latter point. Besides the fore-
going measurements, six others were taken

292

DENUDATION OF THE LAND. Chap. VI.

near together in one of the circular trenches,
on the north-east side; and the mould here
had a mean thickness of 2.29 inches; while the
mean of six other measurements on the south-
west side was only 1.46 inches. These obser-
vations indicate that the castings had been
blown by the south-west winds from the cir-
cular enclosed space into the trench on the
north-east side; but many more measurements
in other analogous cases would be requisite
for a trustworthy result.

The amount of fine earth brought to the
surface under the form of castings, and after-
wards transported by the winds accompanied
by rain, or that which flows and rolls down
an inclined surface, no doubt is small in the
course of a few scores of years; for otherwise
all the inequalities in our pasture-fields would
be smoothed within a much shorter period
than appears to be the case. But the amount
which is thus transported in the course of
thousands of years cannot fail to be consider-
able and deserves attention. E. de Beaumont
looks at the vegetable mould which every-
where covers the land as a fixed line or zero,

Chap. VI.

ANCIENT MOUNDS.

293

from which the amount of denudation may be
measured.* He ignores the continued forma-
tion of fresh mould by the disintegration of
the underlying rocks and fragments of rock;
and it is curious to find how much more philo-
sophical were the views, maintained long ago,
by Playfair, who, in 1802, wrote, “ In the per-
manence of a coat of vegetable mould on the
surface of the earth, we have a demonstrative
proof of the continued destruction of the
rocks.” *

Ancient encampments and tumuli. — E. de
Beaumont adduces the present state of many
ancient encampments and tumuli and of old
ploughed fields, as evidence that the surface
of the land undergoes hardly any degradation.
But it does not appear that he ever examined
the thickness of the mould over different parts
of such old remains. He relies chiefly on in-
direct, but apparently trustworthy, evidence
that the slopes of the old embankments are the

* “ Le£ons de Geologie pratique,” 1845 ; cinqui&me Le5on.
All Elie de Beaumont’s arguments are admirably controverted
by Prof. A. Geikie in his essay in “Transact. Geolog. Soc. of
Glasgow,” vol. iii. p. 153, 1868.

f “ Illustrations of the Huttonian Theory of the Earth,” p.
107.

294

DENUDATION OF THE LAND. Chap. VI.

same as they originally were; and it is obvious
that he could know nothing about their origi-
nal heights. In Knole Park a mound had
been thrown up behind the rifle-targets, which
appeared to have been formed of earth origi-
nally supported by square blocks of turf. The
sides sloped, as nearly as I could estimate them,
at an angle of 45 ° or 50° with the horizon,
and they were covered, especially on the north-
ern side, with long coarse grass, beneath which
many worm-castings were found. These had
flowed bodily downwards, and others had
rolled down as pellets. Hence it is certain
that as long as a mound of this kind is ten-
anted by worms, its height will be continually
lowered. The fine earth which flows or rolls
down the sides of such a mound accumulates
at its base in the form of a talus. A bed, even
a very thin bed, of fine earth is eminently fa-
vourable for worms; so that a greater number
of castings would tend to be ejected on a talus
thus formed than elsewhere; and these would
be partially washed away by every heavy
shower and be spread over the adjoining level
ground. The final result would be the lower-

Chap. VI. ANCIENTLY PLOUGHED FIELDS. 295

in g of the whole mound, whilst the inclina-
tion of the sides would not be greatly lessened.
The same result would assuredly follow with
ancient embankments and tumuli ; except
where they had been formed of gravel or of
nearly pure sand, as such matter is unfavour-
able for worms. Many old fortifications and
tumuli are believed to be at least 2000 years
old; and we should bear in mind that in many
places about one inch of mould is brought to
the surface in 5 years or two inches in 10 years.
Therefore in so long a period as 2000 years,
a large amount of earth will have been repeat-
edly brought to the surface on most old em-
bankments and tumuli, especially on the talus
round their bases, and much of this earth will
have been washed completely away. We may
therefore conclude that all ancient mounds,
when not formed of materials unfavourable to
worms, will have been somewhat lowered in
the course of centuries, although their inclina-
tions may not have been greatly changed.

Fields formerly ploughed. — From a very re-
mote period and in many countries, land has
been ploughed, so that convex beds, called

296 DENUDATION OF THE LAND. Ciiap. VI.

crowns or ridges, usually about 8 feet across
and separated by furrows, have been thrown
up. The furrows are directed so as to carry off
the surface water. In my attempts to ascer-
tain how long a time these crowns and furrows
last, when ploughed land has been converted
into pasture, obstacles of many kinds were en-
countered. It is rarely known when a field
was last ploughed; and some fields which were
thought to have been in pasture from time
immemorial were afterwards discovered to
have been ploughed only 50 or 60 years before.
During the early part of the present century,
when the price of corn was very high, land of
all kinds seems to have been ploughed in Brit-
ain. There is, however, no reason to doubt
that in many cases the old crowns and furrows
have been preserved from a very ancient pe-
riod.* That they should have been preserved

* Mr. E. Tylor in his Presidential address (“Journal of the
Anthropological Institute,” May, 1880, p. 451) remarks: “It
appears from several papers of the Berlin Society as to the
German ‘ high-fields ’ or ‘ heathen-fields * (Hochacker, and
Heidenacker) that they correspond much in their situation on
hills and wastes with the * elf-furrows’ of Scotland, which popu-
lar mythology accounts for by the story of the fields having been
put under a Papal interdict, so that people took to cultivating

Chap. VI. ANCIENTLY PLOUGHED FIELDS. 297

for very unequal lengths of time would natu-
rally follow from the crowns, when first thrown
up, having differed much in height in differ-
ent districts, as is now the case with recently
ploughed land.

In old pasture-fields, the mould, wherever
measurements were made, was found to be
from i to 2 inches thicker in the furrows than
on the crowns; but this would naturally fol-
low from the finer earth having been washed
from the crowns into the furrows before the
land was well clothed with turf; and it is im-
possible to tell what part worms may have
played in the work. Nevertheless from what
we have seen, castings would certainly tend to
flow and to be washed during heavy rains from
the crowns into the furrows. But as soon as
a bed of fine earth had by any means been ac-
cumulated in the furrows, it would be more
favourable for worms than the other parts, and
a greater number of castings would be thrown
up here than elsewhere; and as the furrows on

the hills. There seems reason to suppose that, like the tilled
plots in the Swedish forests which tradition ascribes to the old
‘ hackers/ the German heathen-fields represent tillage by an
ancient and barbaric population.”

20

298 DENUDATION OF THE LAND. Chap. VI.

sloping lands are usually directed so as to
carry off the surface water, some of the finest
earth would be washed from the castings which
had been here ejected and be carried completely
away. The result would be that the furrows
would be filled up very slowly, while the
crowns would be lowered perhaps still more
slowly by the flowing and rolling of the cast-
ings down their gentle inclinations into the
furrows.

Nevertheless it might be expected that old
furrows, especially those on a sloping surface,
would in the course of time be filled up and
disappear. Some careful observers, however,
who examined fields for me in Gloucestershire
and Staffordshire, could not detect any differ-
ence in the state of the furrows in the upper
and lower parts of sloping fields, supposed to
have been long in pasture; and they came to
the conclusion that the crowns and furrows
would last for an almost endless number of
centuries. On the other hand the process of
obliteration seems to have commenced in some
places. Thus in a grass-field in North Wales,
known to have been ploughed about 65 years

Chap. VI. ANCIENTLY PLOUGHED FIELDS. 299

ago, which sloped at an angle of 150 to the
north-east, the depth of the furrows (only 7 feet
apart) was carefully measured, and was found
to be about 4^ inches in the upper part of the
slope, and only 1 inch near the base, where
they could be traced with difficulty. On an-
other field sloping at about the same angle to
the south-west, the furrows were scarcely per-
ceptible in the lower part; although these same
furrows when followed on to some adjoining
level ground were from 2\ to 3 J * inches in
depth. third and closely similar case was
observed. In a fourth case, the mould in a
furrow in the upper part of a sloping field was
2\ inches, and in the lower part 4^ inches in
thickness.

On the Chalk Downs at about a mile dis-
tance from Stonehenge, my son William ex-
amined a grass-covered, furrowed surface, slop-
ing at from 8° to io°, which an old shepherd
said had not been ploughed within the memory
of man. The depth of one furrow was meas-
ured at 16 points in a length of 68 paces, and
was found to be deeper where the slope was
greatest and where less earth would naturally

300

DENUDATION OF THE LAND. Chap. VI.

tend to accumulate, and at the base it almost
disappeared. The thickness of the mould in
this furrow in the upper part was 2\ inches,
which increased to 5 inches a little above the
steepest part of the slope; and at the base, in
the middle of the narrow valley, at a point
which the furrow, if continued would have
struck, it amounted to 7 inches. On the op-
posite side of the valley, there were very faint,
almost obliterated, traces of furrows. Another
analogous but not so decided a case was ob-
served at a few miles distance from Stone-
henge. On the whole it appears that the
crowns and furrows on land formerly ploughed,
but now covered with grass, tend slowly to
disappear when the surface is inclined; and
this is probably in large part due to the action
of worms; but that the crowns and furrows
last for a very long time when the surface is
nearly level.

Formation and amount of mould over the
Chalk Formation. — Worm-castings are often
ejected in extraordinary numbers on steep,

, grass-covered slopes, where the chalk comes
’ close to the surface, as my son William ob-

Chap. VI. MOULD OVER THE CHALK. 301

served near Winchester and elsewhere. If
such castings are largely washed away during
heavy rains, it is difficult to understand at
first how any mould can still remain on our
Downs, as there does not appear any evident
means for supplying the loss. There is, more-
over, another cause of loss, namely in the per-
colation of the finer particles of earth into the
fissures in the chalk and into the chalk itself.
These considerations led me to doubt for a
time whether I had not exaggerated the
amount of fine earth which flows or rolls down
grass-covered slopes under the form of cast-
ings; and I sought for additional information.
In some places, the castings on Chalk Downs
consist largely of calcareous matter, and here
the supply is of course unlimited. But in other
places, for instance on a part of Teg Down
near Winchester, the castings were all black
and did not effervesce with acids. The mould
over the chalk was here only from 3 to 4 inches
in thickness. So again on the plain near
Stonehenge, the mould, apparently free from
calcareous matter, averaged rather less than 3^
inches in thickness. Why worms should pene-

302

DENUDATION OF THE LAND. Chap. VI.

trate and bring up chalk in some places and not
in others I do not know.

In many districts where the land is nearly
level, a bed several feet in thickness of red
clay full of unworn flints overlies the Upper
Chalk. This overlying matter, the surface of
which has been converted into mould, consists
of the undissolved residue from the chalk. It
may be well here to recall the case of the frag-
ments of chalk buried beneath worm-castings
on one of my fields, the angles of which were
so completely rounded in the course of 29
years that the fragments now resembled water-
worn pebbles. This must have been effected
by the carbonic acid in the rain and in the
ground, by the humus-acids, and by the cor-
roding power of living roots. Why a thick
mass of residue has not been left on the chalk,
wherever the land is nearly level, may perhaps
be accounted for by the percolation of the fine
particles into the fissures, which are often pres-
ent in the chalk and are either open or are filled
up with impure chalk, or into the solid chalk
itself. That such percolation occurs can hard-
ly be doubted. My son collected some pow-

Chap. VI. MOULD OVER THE CHALK.

303

dered and fragmentary chalk beneath the turf
near Winchester; the former was found by
Colonel Pabsons, R. E., to contain 10 per cent.,
and the fragments 8 per cent, of earthy matter.
On the flanks of the escarpment near Abinger
in Surrey, some chalk close beneath a layer
of flints, 2 inches in thickness and covered by
8 inches of mould, yielded a residue of 3.7 per
cent, of earthy matter. On the other hand
the Upper Chalk properly contains, as I was
informed by the late David Forbes who had
made many analyses, only from 1 to 2 per cent,
of earthy matter; and two samples from pits
near my house contained 1.3 and 0.6 per cent.
I mention these latter cases because, from the
thickness of the overlying bed of red clay with
flints, I had imagined that the underlying
chalk might here be less pure than elsewhere.
The cause of the residue accumulating more
in some places than in others, may be attrib-
uted to a layer of argillaceous matter having
been left at an early period on the chalk, and
this would check the subsequent percolation
of earthy matter into it.

From the facts now given we may conclude

304

DENUDATION OF THE LAND. Chap. VI.

that castings ejected on our Chalk Downs suf-
fer some loss by the percolation of their finer
matter into the chalk. But such impure su-
perficial chalk, when dissolved, would leave a
larger supply of earthy matter to be added
to the mould than in the case of pure chalk.
Besides the loss caused by percolation, some
fine earth is certainly washed down the slop-
ing grass-covered surfaces of our Downs. The
washing-down process, however, will be
checked in the course of time; for although
I do not know how thin a layer of mould suf-
fices to support worms, yet a limit must at last
be reached; and then their castings would
cease to be ejected or would become scanty.

The following cases show that a consider-
able quantity of fine earth is washed down.
The thickness of the mould was measured at
points 12 yards apart across a small valley in
the chalk near Winchester. The sides sloped
gently at first; then became inclined at about
20°; then more gently to near the bottom,
which transversely was almost level and about
50 yards across. In the bottom, the mean
thickness of the mould from five measurements

Chap. VI. MOULD OVER THE CHALK.

305

was 8.3 inches; whilst on the sides of the val-
ley, where the inclination varied between 140
and 200, its mean thickness was rather less
than 3.5 inches. As the turf-covered bottom
of the valley sloped at an angle of only be-
tween 20 and 30, it is probable that most of the
8.3-inch layer of mould had been washed down
from the flanks of the valley, and not from the
upper part. But as a shepherd said that he
had seen water flowing in this valley after the
sudden thawing of snow, it is possible that
some earth may have been brought down from
the upper part; or, on the other hand, that
some may have been carried further down the
valley. Closely similar results, with respect to
the thickness of the mould, were obtained in
a neighbouring valley.

St. Catherine’s Hill, near Winchester, is
327 feet in height, and consists of a steep cone
of chalk about \ of a mile in diameter. The
upper part was converted by the Romans, or,
as some think, by the ancient Britons, into an
encampment, by the excavation of a deep and
broad ditch all round it. Most of the chalk
removed during the work was thrown up-

306 DENUDATION OF THE LAND. Chap. VI.

wards, by which a projecting bank was formed;
and this effectually prevents worm-castings
(which are numerous in parts), stones, and
other objects from being washed or rolled into
the ditch. The mould on the upper and for-
tified part of the hill was found to be in most
places only from 2\ to 3^ inches in thickness;
whereas it had accumulated at the foot of the
embankment above the ditch to a thickness in
most places of from 8 to 9J inches. On the
embankment itself the mould was only 1 to i|
inch in thickness; and within the ditch at the
bottom it varied from 2\ to 3 J, but was in one
spot 6 inches in thickness. On the north-
west side of the hill, either no embankment had
ever been thrown up above the ditch, or it had
subsequently been removed; so that here there
was nothing to prevent worm-castings, earth
and stones being washed into the ditch, at the
bottom of which the mould formed a layer
from 11 to 22 inches in thickness. It should
however be stated that here and on other parts
of the slope, the bed of mould often contained
fragments of chalk and flint which had ob-
viously rolled down at different times from

Chap. VI. MOULD OVER THE CHALK.

307

above. The interstices in the underlying frag-
mentary chalk were also filled up with mould.

My son examined the surface of this hill to
its base in a south-west direction. Beneath
the great ditch, where the slope was about 240,
the mould was very thin, namely from ij to
2\ inches; whilst near the base, where the
slope was only 30 to 40, it increased to be-
tween 8 and 9 inches in thickness. We may
therefore conclude that on this artificially mod-
ified hill, as well as in the natural valleys of
the neighbouring Chalk Downs, some fine
earth, probably derived in large part from
worm-castings, is washed down, and accumu-
lates in the lower parts, notwithstanding the
percolation of an unknown quantity into the
underlying chalk; a supply of fresh earthy
matter being afforded by the dissolution of the
chalk through atmospheric and other agencies.

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 re-
mains— 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 par-

308

Chap. VII.

CONCLUSION.

309

tides 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 by
many half-decayed leaves which worms con-
sume. Thus the particles of earth, forming
the superficial mould, are subjected to condi-
tions eminently favourable for their decompo-
sition and disintegration. Moreover, the par-
ticles of the softer rocks suffer some amount of
mechanical trituration in the muscular gizzards
of worms, in which small stones serve as mill-
stones.

The finely levigated castings, when brought
to the surface in a moist condition, flow during
rainy weather down any moderate slope; and
the smaller particles are washed far down even
a gently inclined surface. Castings when dry
often crumble into small pellets, and these are
apt to roll down any sloping surface. Where
the land is quite level and is covered with herb-
age, and where the climate is humid so that

3io

CONCLUSION.

Chap. VII.

much dust cannot be blown away, it appears
at first sight impossible that there should be
any appreciable amount of subaerial denuda-
tion; but worm-castings are blown, especially
whilst moist and viscid, in one uniform direc-
tion by the prevalent winds which are accom-
panied by rain. By these several means the
superficial mould is prevented from accumu-
lating to a great thickness; and a thick bed of
mould checks in many ways the disintegration
of the underlying rocks and fragments of rock.

The removal of worm-castings by the above
means leads to results which are far from in-
significant. It has been shown that a layer of
earth, .2 of an inch in thickness, is in many
places annually brought to the surface per
acre; and if a small part of this amount flows,
or rolls, or is washed, even for a short distance
down every inclined surface, or is repeatedly
blown in one direction, a great effect will be
produced in the course of- ages. It was found
by measurements and calculations that on a
surface with a mean inclination of 90 26', 2.4
cubic inches of earth which had been ejected by
worms crossed, in the course of a year, a hori-

Chap. VII.

CONCLUSION.

3”

zontal line one yard in length; so that 240
cubic inches would cross a line 100 yards in
length. This latter amount in a damp state
would weigh 11J pounds. Thus a consider-
able weight of earth is continually moving
down each side of every valley, and will in time
reach its bed. Finally, this earth will be trans-
ported by the 'Streams flowing in the valleys
into the ocean, the great receptacle for all mat-
ter denuded from the land. It is known from
the amount of sediment annually delivered into
the sea by the Mississippi, that its enormous
drainage-area must on an average be lowered
.00263 of an inch each year; and this would
suffice in four and a half million years to lower
the whole drainage-area to the level of the sea-
shore. So that, if a small fraction of the layer
of fine earth, .2 of an inch in thickness, which
is annually brought to the surface by worms,
is carried away, a great result cannot fail to
be produced within a period which no geolo-
gist considers extremely long.

Archaeologists ought to be grateful to
worms, as they protect and preserve for an

312

CONCLUSION.

Chap. VII.

indefinitely long period every object, not liable
to decay, which is dropped on the surface of
the land, by burying it beneath their castings.
Thus, also, many elegant and curious tessel-
lated pavements and other ancient remains
have been preserved; though no doubt the
worms have in these cases been largely aided
by earth washed and blown from the adjoining
land, especially when cultivated. The old tes-
sellated pavements have, however, often suf-
fered by having subsided unequally from be-
ing unequally undermined by the "worms. Even
old massive walls may be undermined and sub-
side; and no building is in this respect safe,
unless the foundations lie 6 or 7 feet beneath
the surface, at a depth at which worms cannot
work. It is probable that many monoliths and
some old walls have fallen down from having
been undermined by worms.

Worms prepare the ground in an excellent
manner for the growth of fibrous-rooted plants
and for seedlings of all kinds. They periodic-
ally expose the mould to the air, and sift it so
that no stones larger than the particles which

Chap. VII.

CONCLUSION.

313

they can swallow are left in it. They mingle
the whole intimately together, like a gardener
who prepares fine soil for his choicest plants.
In this state it is well fitted to retain moisture
and to absorb all soluble substances, as well
as for the process of nitrification. The bones
of dead animals, the harder parts of insects, the
shells of land-molluscs, leaves, twigs, &c., are
before long all buried beneath the accumulated
castings of worms, and are thus brought in a
more or less decayed state within reach of the
roots of plants. Worms likewise drag an in-
finite number of dead leaves and other parts of
plants into their burrows, partly for the sake of
plugging them up and partly as food.

The leaves which are dragged into the bur-
rows as food, after being torn into the finest
shreds, partially digested, and saturated with
the intestinal and urinary secretions, are com-
mingled with much earth. This earth forms
the dark-coloured, rich humus which almost
everywhere covers the surface of the land with
a fairly well-defined layer or mantle. Von
Hensen * placed two worms in a vessel 18

* “ Zeitschrift fur wissenschaft. Zool.,” B. xxviii., 1877, P* 360.

21

314

CONCLUSION.

Chap. VII.

inches in diameter, which was filled with sand,
on which fallen leaves were strewed; and these
were soon dragged into their burrows to a
depth of 3 inches. After about 6 weeks an
almost uniform layer of sand, a centimetre (.4
inch) in thickness, was converted into humus
by having passed through the alimentary
canals of these two worms. It is believed by
some persons that worm-burrows, which often
penetrate the ground almost perpendicularly
to a depth of 5 or 6 feet, materially aid in its
drainage; notwithstanding that the viscid cast-
ings piled over the mouths of the burrows pre-
vent or check the rain-water directly entering
them. They allow the air to penetrate deeply
into the ground. They also greatly facilitate
the downward passage of roots of moderate
size; and these will be nourished by the humus
with which the burrows are lined. Many seeds
owe their germination to having been covered
by castings; and others buried to a consider-
able depth beneath accumulated castings lie
dormant, until at some future time they are
accidentally uncovered and germinate.

Worms are poorly provided with sense-

Chap. VII.

CONCLUSION.

315

organs, for they cannot be said to see, al-
though they can just distinguish between light
and darkness; they are completely deaf, and
have only a feeble power of smell; the sense
of touch alone is well developed. They can
therefore learn little about the outside world,
and it is surprising that they should exhibit
some skill in lining their burrows with their
castings and with leaves, and in the case of
some species in piling up their castings into
tower-like constructions. But it is far more
surprising that they should apparently exhibit
some degree of intelligence instead of a mere
blind instinctive impulse, in their manner of
plugging up the mouths of their burrows.
They act in nearly the same manner as would
a man, who had to close a cylindrical tube
with different kinds of leaves, petioles, trian-
gles of paper, &c., for they commonly seize
such objects by their pointed ends. But with
thin objects a certain number are drawn in by
their broader ends. They do not act in the
same unvarying manner in all cases, as do most
of the lower animals; for instance, they do not
drag in leaves by their foot-stalks, unless the

3 16

CONCLUSION.

Chap. VII.

basal part of the blade is as narrow as the apex,
or narrower than it.

When we behold a wide, turf-covered ex-
panse, we should remember that its smooth-
ness, on which so much of its beauty depends,
is mainly due to all the inequalities having
been slowly levelled by worms. It is a mar-
vellous reflection that the whole of the super-
ficial mould over any such expanse has passed,
and will again pass, every few years through
the bodies of worms. The plough is one of
the most ancient and most valuable of man’s
inventions; but long before he existed the land
was in fact regularly ploughed, and still con-
tinues to be thus ploughed by* earth-worms.
It may be doubted whether there are many
other animals which have played so important
a part in the history of the world, as have
these lowly organised creatures. Some other
animals, however, still more lowly organised,
namely corals, have done far more conspicuous
work in having constructed innumerable reefs
and islands in the great oceans; but these are
almost confined to the tropical zones.

INDEX.

Abinger, Roman villa at, 178.

castings from Roman villa, with rounded particles, 256.

Acids of humus, action on rocks, 243.

Africa, dust from, 237.

Air, currents of, worms sensitive to, 28.

Amount of earth brought to the surface by worms, 129.
Ants, intelligence of, 94.

Archiac, D’, criticisms on my views, 4.

Artemisia, leaves of, not eaten by worms, 33.

Ash-tree, petioles of, 80.

Beaulieu Abbey, burial of the old pavement, 196.

castings from, with rounded particles, 257.

Beaumont, Elie de, on vegetable mould, 2.

the rubbish underlying great cities, 180.

the transport of dust, 240.

the permanence of mould, 292.

the permanence of ancient tumuli, 293.

Beach-forests, stones not buried under by castings, 147.
Bengal, worms of, 124.

Bones, crushed, burial of, under castings, 148.

Brading, Roman villa at, 202.

castings from, with rounded particles, 257.

Bridgman, Mr., on worms eating leaves of a Phlox, 33.
Buckman, on grasses profiting by being rolled, 10.

Burial of the remains of ancient buildings by worms, 178.
Burrows, depth of, hi.

317

318

INDEX.

Burrows, direction of, on a slope, 273.

excavation of, 100.

lined with black earth, 112.

lined with leaves, 113.

mouths of, worms lie motionless near, 15.

old, their collapse, 119.

plugged up, 59.

terminating in a small chamber, often lined with

stones or seeds, 115.

Calciferous glands, 18, 44.

Cannibal worms, 37.

Carnagie, Mr., depth of burrows, 116.

Castings, acid, 53.

— — from Beaulieu, 102.

tower-like, near Nice, 108.

ejection of, 118.

tower-like, from near Calcutta, 125.

— - — of great size on the Nilgiri Mountains, 128.

weight of, from a single burrow and from a given

area, 162.

thickness of layer formed from, during a year, 171.

ejected over ancient buildings, 256.

floating down slopes, 264.

washed away, 275.

dry, disintegration of, 278.

blown to leeward, 286.

Cells, free, with calcareous matter in the calciferous
glands, 48.

Cellulose, digestion of, 38.

Chalk-formation, surface of, much denuded, 139.

Chalk, residue of, forming a superficial deposit, 140.

fragments of, soon buried and corroded, 141.

formation of mould over, 300.

Chedworth, Roman villa of, 200.

Circular trenches near Stonehenge, 290.

Claparede, structure of the intestines of worms, 19.

on the salivary glands of worms, 43.

INDEX.

319

Claparede on the calciferous glands, 44.

the pharynx adapted for suction, 57.

doubts whether earth serves worms as food, 103, 105.

on the gizzards of worms, 249.

Clematis, petioles of, used in plugging up burrows, 59, 78.
Cobra-snake, intelligence of, 96.

Collapsing of old burrows, 120.

Concluding remarks, 308.

Concretions of lime in the anterior calciferous glands, 46.

calcareous, use of, 54.

Corals, mud derived from, 259.

Corniche Road, disintegrated castings on, 280, 284.

Croll, Mr., on denudation, 236.

Crowns or ridges on old ploughed fields, 295.

Currents of air, worms sensitive to, 28.

Dancer, Mr., on the action and number of worms, 148, 161.
Deafness of worms, 26.

Debris, over the Roman remains at Silchester, 203.

Decay of leaves not hastened by the secretion with which
they are bathed, 38.

Denudation of the land, 233.

Depth to which worms burrow, m.

Digaster, 249.

Digestion of worms, 37.

extra-stomachal, 44.

Disintegration of rocks, aided by worms, 243.

Distribution of worms, 122.

Down, amount of earth here brought annually to the sur-
face, 139.

Downs near Winchester, valleys in, 304.

Dust, distance transported, 238-240.

Earth, amount of, brought to the surface by worms, 129.

amount of, which flows down a given slope, 269.

swallowed as food, 101.

weight of, ejected from a single burrow, 162.

Eisen, number of species of worms, 9.

320

INDEX.

Eisen, depth of burrows, in.

Ejection of castings, 118.

Embankments on hill-sides, 281-285.

Encampments, ancient, 293.

Ernst, Dr., on worms at Caracas, 123.

Excavation of the burrows, 100.

Fabre, M., on the instincts of Sphex, 95.

Farrer, Mr. T. H., on the Roman villa at Abinger, 180-190.
Fat eaten by worms, 37.

Fields formerly ploughed, 295.

Fish, Mr., criticisms on my views, 6.

Flints, standing vertically in the residue over the chalk, 140.

acted on externally and internally by atmospheric

agencies, 248.

Flowing down of castings, 264.

Fluid, digestive, of worms, 37.

Food of worms, leaves, 36.

earth, 101.

Foster, Michael, on the pancreatic ferment, 37.

on the acidity of the contents of the intestines, 52.

Foundations, deep, of the Roman buildings at Wroxeter,
229.

Furrows on old ploughed fields, 295.

Galton, Mr., on the number of dead worms, 14.

Geikie, Archibald, on Denudation, 236.

controverts E. de Beaumont’s views on Denudation, 292.

, James, controverts Richthofen’s views, 240.

on glaciated rocks, 248.

Geographical distribution of worms, 122.

Gizzards of worms, 249.

Glands, calciferous, 18, 44.

function of, 50.

Glen Roy, evidence of rarity of debacles, 263.

Haast, Von, on aboriginal instruments in New Zealand
found buried, 149.

INDEX.

321

Hearing, sense of, 26.

Heat, perception of, 26.

Heaths, inhabited by few worms, except where paths cross
them, 10.

Hensen on the number of worms in gardens, 5.

on worms not subsisting on earth, no.

depth of burrows, m.

on number of worms living in a given area, 160.

on the composition of mould, 241.

on the amount of humus formed by two worms, 313.

Henslow, Prof., on ledges on hill-sides, 281.

Hoffmeister, number of species of worms, 9.

on worms hybernating in company, 34.

perception of light by worms, 20, 22.

on the enemies of worms, 63.

depth of burrows, in.

on hybernation of worms, 115.

Hooker, Sir J., on ledges of earth on the Himalaya, 281.
Humus acids, action of, on rocks, 243, 247.

Instinct of worms, 35.

Intelligence of worms, 35, 65.

Intestines of worms, their contents acid, 51.

Islands, inhabited by worms, 122.

Johnson, Dr. H., on the Roman remains at Wroxeter, 225-
231.

on ammonia in worm-castings, 245.

Johnson, S. W., “ How Crops Feed,” 245.

Joyce, Rev. J. G., on the Roman remains at Silchester, 204.
Julien, Mr. A. A., on the composition of peat, 241.

on the humus acids, 243, 247.

Key, Rev. H., on the burial of cinders by worms, 148.
King, Dr., on the formation of mould in forests in France, 5.
on castings near Nice, 107, 118.

on great castings on the Nilgiri Mountains and in Cey-
lon, 128.

322

INDEX.

King, Dr., weight of castings near Nice, 165.

on disintegrated castings on the Corniche road, 279, 283.

on the washing away of the castings on the Nilgiri

Mountains, 277.

Knole Park, beech-woods, worms absent, 12.

Koninck, De, on the disintegration of rocks, 238.

Laburnum leaves, 68.

Land, denudation of, 233.

Lankester, Ray, on the structure of worms, 18.

on worms from Kerguelen Land, 122.

La Plata, dust storms of, 239.

Layard, Mr., on the habits of the cobra, 96.

Leaves, worms distinguish the taste of different kinds, 32.
consumed by worms, 36.

their decay not hastened by the alkaline secretion

with which they are bathed, 39.

decayed, generate acids, 51.

used in plugging up burrows, 66.

used to line burrows, 113.

Ledges of earth on hill-sides, 281.

Leon, F., on the digestive fluid of worms, 37.

Light, perception of, by worms, 20.

Lime, carbonate, concretions of, 46.

Maer Hall, amount of earth brought to surface, 132.
Mallett, Mr., on the sinking of the ground under great
buildings, 160.

Meat, raw, eaten by worms, 36.

Mental qualities of worms, 34.

Mint, leaves of, only nibbled, 33.

Mississippi, drainage area of, 236.

Mobius on the habits of a pike, 96.

Moniligaster, 249.

Morren on worms surviving long immersion, 13.

on worms lying motionless near mouths of their bur-
rows, 16.

on worms eating sugar, 36.

INDEX.

323

Morren on the disappearance of the calciferous glands dur-
ing winter, 49.

on stones in the gizzards of worms, 250, 252.

Mould, thickness of, annually ejected by worms, 171.

■ thickness of, over Roman remains at Chedworth, 201.

nature and thickness of, over the Roman remains at

Silchester, 221.

thickness of, at Wroxeter, 225.

formation and thickness of, over the chalk, 300.

Mountains, worms absent from, 12.

Muller, Fritz, on the worms in South Brazil, 123.

Nice, castings near, 107.

disintegrated castings near, 279.

Night, worms leave their burrows, 14.

Nilgiri Mountains, castings on, 128.

Objects strewed on the surface soon buried under castings,
132.

Obliteration of old furrows on ploughed land, 295.

Odours, degree of sensitiveness to, by worms, 29.

Pancreatic secretion, 37.

not acid, 53.

Paper, triangles of, 84.

Path, paved, burial of, by worm-castings, 147.

Paths inhabited by worms, 10.

Pavement, modern, undermined by worms, 194.
Pavements, ancient, subsidence of, at Silchester, 214.

Peat, formation of, 242.

Percolation of earth into the chalk, 301.

Perichaeta, naturalized near Nice, 108.

Perrier, worms surviving long immersion, 13.

on the calciferous glands, 44.

on the action of the pharynx, 57.

on the burrowing power of worms, 100.

on naturalized worms, 108.

on worms killed by acetic acid, 162.

324

INDEX.

Perrier on the gizzards of worms, 249, 252.

Petioles of Clematis, 78.

of the ash, 80.

Pharynx, action of, 57.

Pike, stupidity of, 95.

Pine-leaves used in plugging up burrows, 59, 72.

lining burrows, 114.

Pipes, formation of, in the chalk, 140.

Playfair on Denudation, 293.

Ploughed fields, old, 295.

Plugging up of the burrows, 59.

use of the process, 63.

Prehension, power of, by worms, 57.

Qualities, mental, of worms, 34.

Ramsay, Mr., on the sinking of a pavement undermined
by worms, 194.

on Denudation, 233.

Remains, ancient, buried by worms, 178.

Rhododendron leaves, 70.

Richthofen on dust deposits in China, 239, 240.

Robinia, petioles of, 82.

Rocks, disintegration of, aided by worms, 243.

triturated in the gizzards of worms, 252.

Rolling down of dry castings, 278.

Romanes, Mr., on the intelligence of animals, 96.

Sachs on living roots corroding rocks, 245, 246.

Sage, leaves of, not eaten by worms, 33.

Saliva, doubtful whether any secreted by worms, 43.
Saussure, H. De, on brick-pebbles, 257.

Schmulewitsch on the digestion of cellulose, 38.

Scott, Mr. J., on worms near Calcutta, 124.

Seeds preserved in the burrows of worms, 116.

Semper on various animals swallowing sand, 104.

Senses of worms, 19.

Silchester, old Roman town, 203.

INDEX.

325

Silica, colloid, acted on by the humus acids, 245.

Sinking of the pavements at Silchester, 215.

Sites inhabited by worms, 9.

Smell, sense of, 29.

Social feelings of worms, 34.

Sorbv, Mr., on the trituration of small particles of rock, 260.
Starch eaten by worms, 36.

digestion of the granules in the cells of leaves, 42.

St. Catherine’s Hill, near Winchester, 305.

Stones, great, undermined by worms at Leith Hill and at
Stonehenge, 193.

small, heaped over burrows, 61.

small, in the gizzards of worms, 250.

rounded in the gizzards of worms, 252.

Stonehenge, great stones of, undermined by worms, 156.

circular trenches near, 290.

Structure of worms, 17.

Subsidence of the pavements at Silchester, 215.

Suction, power of, 57.

Sugar eaten by worms, 36.

Summary of whole book, 308.

Surface, objects strewed on, buried under castings, 133.
Taste, power of, 32.

Thickness of the layer of mould annually ejected by worms,

171.

of the mould over the remains at Chedworth, 201.

of the mould over the remains at Silchester, 221.

of the mould over the Roman remains at Wroxeter, 225.

Thyme, leaves of, not eaten by worms, 33.

Touch, worms highly sensitive to, 28.

Triangles of paper, 84.

Trituration of particles of rock in the gizzards of worms,
252.

Tumuli, ancient, 293.

Tylor, Mr. A., on Denudation, 236.

Tylor, Mr. E., on anciently ploughed land, 296.

Typhosolis, 19.

326 INDEX.

Utricularia, bladders of, no.

Vibrations, worms sensitive to, 27.

Vision, power of, in worms, 20.

Walls, ancient, at Abinger, penetrated by worms, 190.

penetrated by worms at Silchester, 212.

Washing away of castings, 275.

Wedgwood, Mr., on the formation of mould, 3.

Weight of earth ejected from a single burrow, 162.
Whitaker, Mr., on Denudation, 235.

White, on worms leaving their burrows at night, 14.
Winchester, chalk formation near, 304.

Wind, action of, on castings, 286.

Worms, nocturnal, 13.

large numbers occasionally die, 14.

dead, eaten by other worms, 37.

contents of intestines, acid, 52.

their castings, acid, 52.

power of suction, 57.

plugging up their burrows, 59.

intelligence of, 65.

formation of their burrows, 99.

number of, living in a given area, 160.

penetrating ancient walls, 190, 212.

gizzards of, and the trituration of the contained stones

249.

prefer to live in fine earth, 294.

Wright, Mr., on the age of Wroxeter, 223.

Wroxeter, old Roman town of, 223.