The formation of vegetable mould, through the action of worms : with observations on their habits

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THE FORMATION

OF

VEGETABLE MOULD

THROUGH THE

AOTIOI^ OF WOEMS.

THE FOEMATION

VEGETABLE MOULD,

THROUGH THE

ACTIOIT OF WOEMS,

WITH

OBSERVATIONS ON THEIR HABITS.

CHARLES DARWIN, LL.D., F.R.S. T

WITH ILL USTRA TJONS.

BOSTON COLLFGK LIBRARY
CHE8TNUT HILL, MA8S.

NEW YORK :
D. APPLETON AND COMPANY,

72 FIFTH AVENUE.
1897.

Authorized Edition.

6til51

CONTENTS.

INTRODUCTION T;iiS,e 1-7

O"

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— Eetreat rapidly when brightly
illuminated, not by a reflex action — Power of atten-
tion— 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 — Calciferons glands, structure of — Cal-
caieous concretions formed in the anterior pair of
glands — The calcareous matter primarily an excre-
tion, but secondarily serves to neutralise the acids
generated during the digestive process . 8-54

IV CONTENaS.

CHAPTER 11.

Habits of worms — contiuued.

Manner in which worms seize objects — Their power of
biintion — The instinct of plugging up the mouths of
their burrows — Stones piled over the burrows —
The advantages thus gained — Intelligence shown by
worms in tbeir manner of plugging up their burrows
■r— Various kinds of leaves and other objects thus
used — Triangles of paper — Summary of reasons for
believing that worms exhibit some intelligence —
Means by which they excavate their burrows, by
pushing away the earth and swallowing it — Earth
also swallowed fur 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 — ^Tho
collapse of old burrows — Distribution of worms —
Tower-like castings in Bengal — Gigantic castings
on the Kilgiri Mountains — Castings ejected in all
countries . . ... . Page 55-128

CHAPTEE 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 tne surface — The number of
worms which live within a given space — The

CONTENTS. V

weight of earth ejected from a burrow, and from all
tho burrows within a given space — The thickness
(f tho 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

Pagre 129-175

"&'■

CHAPTER IV.

THE TAJ IT WHICH WORMS HAVE PLAYED IN THE
BURIAL OF ANCIENT BUILDINGS.

The accumulation of lubbish on the sites of great cities
independent of the action of worms — Tho burial of
a Eoman villa at Abinger — The floors and walls
penetrated by worms — Subsidence of a modern
pavement — The buried pavement at Beaulien Abbey
— Eoman villas at Ched worth and Brading — The
remains of the Eoman town at Silchester — Tho
nature of the debris by which the remains are
covered — The penetration of the tesselated floors
and walls by worms — Subsidence of the fioors —
Thickness of the mould — The old Eoman city of
Wroxeter — Thickness of the mould — Depth of tho
foundations of some of the buildings — Conclubion

17G-22D

ghapt:se y.

THE ACTION OF WORUS IN THE DENUDATION OF
THE LAND.

Sviience of the amount of denudation which the sand
Las undergone — Subaerial denudation — The deposi-
tion of dust — Vegetable mould, its dark coloar an.^

vi CONTENTS.

fine texture largely due to the action of worms—
j'he disintegration of rocks by the humus-acids — •
Similar acids apparently generated within tlie
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 underljdng soil and rocks — Particles of stone
worn or triturated in tbe gizzards of worms —
Swallowed stones serve as millstones — The levigated
state of the castings — Fragments of brick in the
castings over ancient buildings well rounded. The
triturating power of worms not quite insignificant
under a geological point of view . Page 230-258

CHAPTER YI.

THE DENUDATION OF THE LAIHD— Continued,

Denudation aided by recently ejected castings flowing
down inclined grass-covered surfaces — The amount
of earth which annually flows downwards — -The
effect of tropical rain on worm castings — The finest
particles of earth washed completely away from
castings — The disintegration of dried castings into
]>ellets, and their rolling down inclined surfaces —
The formation of little ledges on hill-sides, in part
due to the accumulation of disintegrated castings —
Castings blown to leeward over level land — An
attempt to estimate the amount thus blown — The
dogradation of ancient encampments and tumuli —
The preservation of the crowns and furrows on land
anciently p!oughed — The formation and amount of
mould over the Chalk formation . . 259-304

CONTENTS. '«'"

CHAPTER YII.

C025CLUSION.

Summary of the part which worms havo played in the
history of the world — Their aid in the disintegra-
tion of rocks — In the denudation of the land — Iii
the preservation of ancient remains — In the pre-
paration of the soil for the growth of plants —
Mental powers of worms — Conclusion . 30«^-ol(i

Index 315-326

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 of the layer of vegetable mould,
which covers the whole surface of the land
in every moderately humid country, is the
subject of the present volume. This mould
is generally 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 com-
posed is one of its chief characteristic features ;
and this may be well observed in any gravelly
country, where a recently-ploughed field

2 INTRODUCTION.

immediately adjoins one which has long re-
mained undisturbed for pasture, and where
the vegetable mould is exposed on the sides
of a ditch or hole. The subject may appear
an insignificant one, but we shall see that
it possesses some interest 5 and the maxim
" de minimis lex non curat," does not apply
to science. Even Elie de Beaumont, who
generally undervalues small agencies 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 regard to its permanence, we shall here-
after see reason to b,elieve that its component
particles are in most cases removed at not a
very slow rate, and are replaced by others
due to the disintegration of the underlying
materials.

As I was led to keep in my study during
many months worms in pots filled with earthy

* ' Lecons de Geologie Pratique,' torn. i. 1845, p. 140

INTEODUCTION. 3

r became interested in them, and wished to
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, Src, 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 ol
castings. These castings are sooner or later

* ' Transactions Geolog. Soc' vol. v. p. 505. Read Novem-
ber 1. 1837.

4 INTKODUCTION.

spread out and cover up any object left on
the surface. I was thus led to conclude that
all the vegetable mould over the whole coun*
try has passed many times through, and will
again pass many times through, the intestinal
canals of worms. Hence the term "animal
mould " would be in some respects more
appropriate than that commonly used of
*' vegetable mould."

Ten years after the publication of my paper,
M. D' Archiac, evidently influenced by the 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 Tappui 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 continually
worked, though in such loose soil they generally
dejTosit their castings in any open cavities or
within their old burrows instead of on the
surface. Yon Hensen estimates that there are

* • Histoire des progrfes de la Geologic,' torn. i. 1847, p. 224,

INTRODUCTION. 5

about twice as many worms in gardens as in
corn-field^,.* With respect to '* prairies
elevees," I do not know how it may be in
France, but nowhere in England have I seen
the ground so thickly covered with castings
as on commons, at a height of several hundred
feet above the sea. In woods again, if the loose
leaves in autumn are removed, the whole
surface will be found strewed with castings.
Dr. King, the superintendent of the Botanic
Grarden in Calcutta, to whose kindness I am
indebted for many observations on earth-
worms, informs me that he found, near Nancy
in France, the bottom of the State forests
covered over many acres with a spongy layer,
composed of dead leaves and innumerable
worm-castings. He there heard the Professor
of " Amenagement des Forets " lecturing to
his pupils, and pointing out this case as a
" beautiful example of the natural cultiva-
'' tion 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 fiir wissenschaft. Zoologl;,* B xxviii. 1877
p* 361.

6 INTRODUCTION.

In tlie year 1869, Mr. Fish* rejected my
conclusions with respect to the part which
worms have played in the formation of veget-
ahle mould, merely on account of their assumed
incapacity to do so much work. He remarks
that ''considering their weakness and their
' size, the work they are represented to
" have accomplished is stupendous." Here wo
have an instance of that inability to sum
up the effects of a continually recurrent
cause, which has often retarded the progress
of science, as formerly in the case of geology,
and more recently in that of the principle
of evolution.

Although these several objections seemed
to me to have no weight, yet I resolved to
make more observations of the same kind as
those published, and to attack the problem on
another side ; namely, to weigh all the cast-
ings 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 observa-
tions have been rendered almost superfluous
by an admirable paper by Yon Hen sen,

* ' Gardeners' Chrouicle,' April 17, 18G9, p. 418.

IKTRODUTIOIS^. 7

already alluded to, whicli 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 ray
own observations and from those of other
naturalists.

HABITS OF WORMS. Chap. L

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 povrer of smell — Taste —
Mental qualities — Nature of food — Omnivorous — Digestion —
Leaves before being swallowed, moistened with a fluid of the
nature of the pancreatic secretion — Extra-stomachal digestion
— Calciferous glands, structure of — Calcareous concretions
formed in the anterior pair of glands — The calcareous matter
primarily an excretion, but secondarily serves to neutralise the
acids generated during the digestive process.

Earth-worms are distributed throughout the
world under the form of a few genera, which
externally are closely similar to one another.
The British species of Lumbricus have never
been carefully monographed; but we may
judge of their probable number from those
inhabiting neighbouring countries. In Scan-
dinavia there are eight species, according to

Chap. I. SITES INHABITED. 9

Eisen ;* but two of these rarely burrow in the
ground, and one inhabit?! very wet places oi
even lives under the water. We are here
t^oncerned only with the kinds which bring
up earth to the surface in tlie form of cast-
ings. Hoifmeister says that the species in
Germany are not well known, but gives the
same number as Eisen, together with some
strongly marked varieties.!

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, wliere 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 appears 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 will be given in which they had

* 'Bidrag till Skandinaviens 01igoclia}tfauna,' 1871.
t * Die bis jetzt bekaunten Arteu aus der Familie der Eegeii*
ftli mer,' 184:5.

10 HABITS OF WOKMS. Chap. L

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 peaf,
which is so much valued by gardeners. On
dry, sandy or gravelly tracks, where heath
with some gorse, ferns, coarse grass, moss and
lichens alone grow, hardly any worms can
be found. But in many parts of England,
wherever a path crosses a heath, its surface
becomes covered with a fine short sw^ard.
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 occasionally manured by the droppings
from animals, I do not know.* On such
grassy paths worm-castings may often be seen.
On a heath in Surrey, which was carefully
examined, there were only a few castings on
these paths, where they were much inclined ;

* 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 Eoyal Agricultural College, remarks (' Gardeners'
Chronicle,' 1854, p. 619) : " Another circumstance in the cultiva-
tion of grasses in the separate form or small patches, is the
impossibility of rolling or treading them firmly, vvithout whioli
uo pasture can continue good."

Chap. I. SITES INHABITED. II

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 thick-
ness cfafew 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, necessary for their
existence ; and the mere compression 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 autumnal rains. Although most cop-
pices and woods support many worms, yet in a
forest of tall and ancient beech-trees in Knole

12 HABITS OF WORMS. Chap. I.

Park, where the ground beneath was bare of
all vegetation, not a single casting could be
fDund over wide spaces, even during the
autumn. Nevertheless, castings were abun-
dant on some grass-covered glades and in-
dentations 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 proximity of the sub-
jacent rocks, into which worms cannot
burrow during the winter so as to escape
being frozen. Dr. Mcintosh, however, found
worm-castings at a height of 1500 feet on
Schiehallion in Scotland. They are numerous
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-
trial animals, though they are still in one
sense semi-aquatic, like the other members of
the great class of annelids to which they
belong. M. Perrier found that their ex-
posure to the dry air of a room for only a
single night was fatal to them. On the

Ohap. I. NOCTUENAL. 13

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 consider-
able depth and cease to work, as they do
during the winter when the ground is frozen.
Worms are nocturnal 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 without being torn into
pieces.f During the day they remain in
their burrows, except at the pairing season,
when those which inhabit adjoining burrows
expose the greater part of their bodies for
an hour or two in the early morning. Sick

* I shall have occasion often to refer to M. Perricr's admirable
memoir, 'Organisation des Lombriciens terrestres' in 'Archives
de Zoolcg. exper.' torn. iii. 1874, p. 372. 0. F. Morren (' De
Lumbrici terrestris,' 1829, p. 14) fouud that worms endured
immersion for fifteen to twenty days in summer, but that ia
vi'inter they died when thus treated.

t Morren, 'De Lumbrici terrestris,' &c., 1829, p. 67.

14 HABITS OF WORMS. CnAr. 1.

individuals, which are generally affected by
the parasitic larvae of a fly, must also be ex-
cepted, as they wander about during the day
and die on the surface. After heavy rain
succeeding dry weather, an astonishing num-
ber of dead worms may sometimes be seen
lying on the ground. Mr. Galton informs
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
jio 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 Sel-
borne long ago knew. In the morning, aftei
there has been heavy rain, the film of mud
or of very fine sand over gravel-w^alks is often

Chap. I. WANDEK FKOM THEIR BUEROWS. 15

plainly marked witli their tracks. I have
ijoticed this from August to May, both months
included, and it probably occurs during the
two remaining 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 innumerable 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 voyage of discovery,
and thus they find new sites to inhabit.

Morren states * that worms often lie for
hours almost motionless close beneath the
mouths of their burrows. I have occasionally
Qoticed the same fact with worms kept in

* ' Do Liimbrici terrestris,' &c., p. 14.

16 HABITS OF WORMS. Chap. 1

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 barrows be suddenly removed, the end
of the worm's body may very often be seen
rapidly retreating. This habit of lying near
the surface leads to their destruction to an
immense extent. Every morning during cer-
tain 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 believe that they lie
near the surface for the sake of warmth, es-
pecially in the morning ; and we shall here-
after find that they often coat the mouths
of their burrows with leaves, apparently to
prevent their 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

Chap. J. THEIR STRUCTURE. 17

consists of from 100 to 200 almost cylindrical
rings or segments, each furnished with minute
bristles. The muscular system is well
developed. 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 tlie 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 ac-
companying diagram (Fig. 1) which is pushed
forwards when the animal eats, and this part
corresponds, according to Perrier, with the pro-
trudable 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 amount of carbonate of lime.
These calciferous glands are highly remark-
able, for nothing like them is known in any
other animal. Their use will be discussed
when we treat of the digestive process. In
most cf the species, the oesophagus is enlarged
into a crop in front of the gizzard. This

18

HABITS OF WORMS.

Chap. L

latter

organ is

Mout'i.

Pharynx.

(Esophagus.

Calciferous glands.

Esophagus.

Crop.

Gizzaid.

1^^ Upper part of
testin.\

Fig . 1.

Diagram of the alimen-
tary canal of an earth-
worm (Lumhricus),
copied from Ray Lan-
kester in ' Quart.
Journ. of Microscop.
Soc' vol. XV. N.S.
pi. vii.

lined with a smooth thick
chitinous membrane, and
is surrounded by weak
longitudinal, but by power-
ful transverse muscles.
Perrier saw these muscles
in energetic action; and, as
he remarks, the trituration
of the food must be chiefly
eflected by this organ, for
worms possess no jaws or
teeth of any kind. Grains
of sand and small stones,
from the 2V ^^ ^ little
more than the ^^ inch in
diameter, may generally
be found in their gizzards
and intestines. As it is
certain that worms swal-
low many little stones, in-
dependently of those swal-
lowed while excavating
their burrows, it is prob-
able that they serve, like
mill-stones, to triturate
their food. The gizzard
opens into tlie intestine,

Chap. I. THEIR SENSES. 19

which runs in a straight course to the vent
at the posterior end of the body. The intes-
tine presents a remarkable structure, the
typhosohs, 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 intestine, by which means an extensive
absorbent 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
at first I thought that they wxre quite in-
sensible to light ; for those kept in confine-
ment were repeatedly observed by the aid of
a candle, and others out of doors by the aid
of a lantern, yet they were rarely alarmed,
although extremely timid animals. Other

* Histolog. Untersucliungeii iiber die Eegenwiirmer. *Zcit-
schrift fiir wissenschaft. Zoologie/ B. xix., 1869, p. 611.

20 HABITS OF WORMS. Cuap. L

persons have found no difficuity in observing
worms at niglit 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 vibration of the floor should be caused.
When under these circumstances worms were
illuminated by. a bull's-eye lantern having
slides of dark red and blue glass, which in-
tercepted so much light that they could be seen
only with some difficulty, they were not at all
affected 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
ao difference in the result. When they were

* For instance, Mr. Bridgman and Mr. Newman (' The
Zoologist/ vol. vii. 1849, p. 2576), and some friends who observtvi
worms for me.

t ' Familie der Regenwiirmer,' 1845, p. 18.

Chap. I. THEIR SENSES. 2i

illuminated by a candle, or even by a bright
paraffin lamp, tbey were not usually affected
at first. Nor were they when the light was
alternately admitted and shut off. Some-
times, however, they behaved very differ-
ently, 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 tapering 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 to side as
if feeling for some object. They appeared
distressed by the light ; but I doubt whether
this was really the case, for on two occasions
after withdrawing slowly, they remained for
a long time with their anterior extremities
protruding a little from the mouths of their
burrows, in which position they were readv
for instant and complete withdrawal.

When the light from a candle was con-
centrated by means of a large lens on the
anterior extremity, they generally withdrew
instantly ; but this concentrated light failed

22 HABITS OF WORMS. Chap. 1

to act perhaps 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 instantly 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.

From the foregoing facts it is evident that
light affects worms by its intensity and by
its duration. It is only the anterior
extremity of the body, where the cerebral
ganglia lie, which is affected by light, as
Hoffmeister asserts, and as I observed on
many occasions. If this part is shaded, other
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

Chap. L THEIE SENSES. 23

different occasions miglit be explained, either
by the degree of extension of their skin and
its consequent transparency, or by some
particular incidence of the liglit ; but I
could discover no such relation. One thing
was manifest, namely that when worms were
employed in dragging leaves into their
burrows or in eating them, and even during
the short intervals whilst they rested from
their work, they either did not perceive
the light or were regardless 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.

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 mann^^r, independently of the will

3

24 HABITS OF WORMS. Chap. I

or consciousness of the animal, as if it were
an automaton. But the different effect
which a h'ght produced on different occasions;
and especially the fact that a worm when in
any way employed and in the intervals ol
such employment, whatever set of muscles
and ganglia may then have been brought into
j)lay, is often regardless of light, are opposed
to the view of the sudden withdrawal being
a simple 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 attribute this to their attention
being then absorbed ; 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 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 another. The comparison
here implied between the actions of one oJ
the higher animals and of one so low in the
scale as an earth-w^orm, may appear far-

Chap. I. THEIR SENSES. 25

fetched ; for we tlms attribute to the worm
attention and some mental power, neverthe-
less 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 become 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 win-
dow, 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 entered between the
sheets of glass and the blackened 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 to
moderate radiant heat than to a bright light.
I judge of this from having held at diflferent

26 HABITS OF WORMS. CiiAP. L

times a poker heated to dull redness near
some worms, at a distance which caused a
very sensible degree of warmth in my hand*
One of them took no notice ; a second with-
drew 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 temper-
ature, as may be inferred from their not
coming out of their burrows during a frost.

Worms do not possess any sense of hearing.
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 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 oi
a piano, which was played as loudly as
possible^ they remained perfectly quiet.

Although they are indifferent to undula-
tions in the air audible by us, they are

Chap. I. THEIR SENSES. 27

extremely sensitive to vibrations 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 instrument, and the note C in the bass
clef was struck, both instantly retreated into
their burrows. After a time they emerged,
and when Gr above the line in the treble clef
was struck they again retreated. Under
similar circumstances 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 occasions 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 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 burrov/s. 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

28 HABITS OF WORMS. Chap. F.

piano ; and their sensitiveness to jars varied
mnch 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, however, the ground is dug with a
fork and is violently 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 Yery narrow chinks thus
left, often sufficed to cause a rapid retreat.
They sometimes perceived tlie eddies in the
air caused by cpickly removing the glass
plates. When a worm first comes out of its
burrow, it generally moves the much ex-
tended 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

Chap. I. THEIR SENSES. 29

notion of the form of an object. Of all tlieir
senses that of touch, including in this term
the perception of a vibration, seems much the
most highly developed.

In worms the sense of smell apparently is
confined to the perception of certain 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-wool soaked in
tobacco juice, and in millefleurs perfume, and
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
probably due to the irritation of their skins.
The perception of such unnatural odours
would be of no service to worms ; and as such

30 HABITS OF WORMS. Chap. L

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 i 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
morning, that is, after a single night ; tv*^o
others after two nights ; and the seventh bit
after three nights. Two pieces of onion were
discovered and removed after three nights.
Bits of fresh raw meat, of which worms are
very fond, were buried, and were not dis-
covered 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 prevent the emission of any odour.

Chjip. I. THEIR SENSES. 31

On two occasions, however, the surface was
well watered, and was thus rendered some-
what compact. After the bits of cabbage and
onion had been remcved, I looked beneath
them to see whether the worms had acci-
dentally 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 ferruginous sand,
which was slightly pressed down and well
watered, so as to be rendered very compact,
and these pieces were never discovered. On
a third occasion the same kind of sand was
neither pressed down nor watered, and the
pieces of cabbage were discovered and re-
moved after the second night. These several
facts indicate that worms possess some power
of smell ; and that they discover by thia

32 HABITS OF WORMS. Chap. L

means odoriferous and mucli-coveted kinds
of food.

It may be presumed that all animals which
feed on various substances possess 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 dis-
tinguish between different varieties ; but this
may perhaps be owing to differences in their
texture. On eleven occasions pieces of the
fresh leaves of a common green variety and
of the red variety used for pickling w^ere
given them, and they preferred the green,
the red being either wholly neglected or much
less gnawed. On two other occasions, how
ever, they seemed to prefer the red. Half-
decayed leaves of the red variety and fresh
leaves of the green were 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,

Chap. I. THEIR SENSES. 33

wild cherry and carrots were given together,
the two latter kinds, especially those of the
carrot, were preferred to all the others,
including those of celery. It was also mani-
fest 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 w^hole
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 of the mint, which were occa-
sionally 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
m the worms for one taste over another.

The Zoologist; vol. vii, 184D, p. 2576.

34 HABITS OF WOE^IS. Chzlp. I,

Mental Qualities. — There is little to be said
on this head. We bav^e seen tbat 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 disturbed by crawling over
each other's bodies, and they sometimes lie
in contact. According to Hoffmeister they
pass the winter either singly or rolled up
with others into a ball at the bottom of their
burrows.* Although worms are so remark-
ably deficient in the several sense-organs,
this does not necessarily preclude intelligence,
as we know from such cases as those of Laura
Bridgman; and we have seen that when theii
attention is engaged, they neglect impressions
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.

* ' Familie rir.r Regenwiirmcr,' p. 13.

Chap. I. MENTAL QUALITIES. 35

They perform a few actions instinctively, that
is, all the individuals, including the young,
perform such actions in nearly the same
i'ashion. This is shown by the manner in
which the species of Perichseta 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 plug-
ging up the mouths of their burrows with
various objects ; and very young worms act
in this manner. But some degree of in-
telligence appears, as we shall see in the next
chapter, to be exhibited in this work, — a
result which has surprised 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 diges-
tible matter which it may contain ; but to
this subject I must recur. They also con-
sume a large number of half-decayed leaves
of all kinds, excepting a few which have an
unpleasant taste or are too tough for them :

36 HABITS OF WORMS. Chap. 1

likewise petioles, peduncles and decayed
flowers. But they will also consume fresh
leaves, as T have found by repeated trials.
According to Morren* they will eat particles
of sugar and liquorice ; 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 loug pins to the
surface of the soil in my pots, and night after
night the worms 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 prefer fresh to putrid
meat, and in so far I differ from Hofirneister.

* ' De Lumbrici terrestris ' p. 19.

CiiAP. I. FOOD AND DIGESTION. 37

Leon Fredericq states* that tlie digestive
fluid of worms is of tlie same natm^e 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
dissolves fibrin, and worms eat raw meat ; it
converts starch into grape-sugar with wonder-
ful rapidity, and vtq shall presently show that
the digestive fluid of worms acts on starch.f
But they 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
attacked by the gastric secretion of the higher
animals, is acted on by that from the pancreas. J

• * Arcliives de Zoologie experimentale/ torn. vii. 1878, p. 394.

t On the action of the pancreatic ferment, see * A Text-Book
cf Physiology,' by Michael Foster, 2n(i edit. pp. 198-203. 1878.

X Schmulewitsch, ' Action des Sues digestifs sur la Cellulose.
Bull, de I'Acad. Imp. de St. Pe'teisbourg, torn. xxv. p. 549.
1879.

38 HABITS OF WORMS. Chap. 1

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 Yerj rnoist atmosphere
under a bell-glass in my study ; and the parts
which had been moistened by the worms did
not decay more quickly in any plain manner
than the 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 tlie juice thus extracted was not alkaline.
Some leaves, however, which had been drawn

CiiAP. I. FOOD AND DIGESTION. 39

into burrows out of doors, at an unknown
antecedent period, were tried, and though still
moist, they rarely exhibited even a trace of
alkaline reaction.

The fluid, with which the leaves are bathed,
acts on thein 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 occasionally 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 become 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

4:0 HABITS OF WORMS. Cuap. L

reflected light; but when viewed as a trans-
parent object under the microscope, minute
specks of h'ght were transmitted, and this
was not the case with the unaffected parts
of the same leaves. These effects, how^-
ever, 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 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
Ihey were affected in a peculiar manner by the
secretion poured out of their mouths. The
upper surfaces of the leaves, over which the

Chap. I. FOOD AND DIGESTION. 41

worms had crawled, as was sliown 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.
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
nothing but broken down granular matter.
These effects must be attributed to the trans-
udation 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-

42 HABITS OF WOEMS. Chap. L

grains are preserved in the guard-cells of tlie
storaata. Now in several cases the starch had
partially or wholly disappeared from these
cells, in the parts which had been moistened by
tlie secretion ; while they were still well pre-
served in the other parts of the same leaves.
Sometimes the starch was dissolved out of
only one of the two guard- eel Is. The
nucleus in one case had disappeared, together
with the starch-granules. The mere burying
of lime-leaves in damp earth 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 seci^etion of tiiis

* C/laparede doubts whether saliva is secretea by worms : see
Zeitschiift fiir wissenschaft. Zoologie,' P>. xix. 1869, p. GOl.

Chap. I. CALCIFEROUS GLANDS. 43

kind is found in the intestines of worms. As
the leaves whicli are dragged into tlie bur-
rows are often dry and shrivelled, it is in-
dispensable 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, probably from habit.
The result is that they are partially digested
before they are taken into the alimentary
canal. I am not aware of any other case of
extra-stomachal digestion having been re-
corded. The boa-constrictor bathes its prey
with saliva^ but this is solely for lubricating
it. Perhaps the nearest analogy may be
found in such plants as Drosera and Dionasa ;
for here animal matter is digested and con-
verted into peptone not within a stomach, but
on the surfaces of the leaves.

Calciferous Glaiids. — These glands (see
Fig. 1), judging from their size and from their
rich supply of blood-vessels, must be of much
importance to the animal. But almost aa
many theories have been advanced on their
use as there have been observers. They
consist of three pairs, which in the common

14 HABITS OF WORMS. Chap. T.

earth-worm debouch into the ahmentary
canal in advance of the gizzard, but pos-
teriorly to it in Urochtsea and some other
genera.* The two posterior pairs are formed
by lamellge, which according to Claparede,
are diverticula from the oesophagus. y These
lamellae are coated with a pulj)y cellular
layer, with the outer cells lying free in in-
finite numbers. If one of these glands is
punctured and squeezed, a quantity of white
pulpy matter exudes, consisting 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 globules 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 of lime. If the cells

* Perrier, ' Archives de Zoolog. exp^r,' July, 1874, pp. 416,
419.

t ' Zeitschrift fiir wissenschaft. Zoologie,' B. xix. 18G9, pp,
603-606.

Chap. I. CALCIFEROUS GLANDS. 45

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
flocculent residue is left, which apparently
consists of the delicate ruptured cell-walls.
In the two posterior pairs of glands the
carbonate of lime contained in the cells oc-
casionally aggregates into small rhombic
crystals or nito concretions, which lie be-
tween the lamellae ; 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 concre-
tion of carbonate of lime, as much as IJ mm.
in diameter. When a gland includes only
a few very small concretions, or, as sometimes
happens, none at all, it is easily overlooked.
The large concretions ai'e round or oval, and
exteriorly almost smooth. One was found
which filled up not only the whole gland, as
is often the case, but its neck ; so that it

46 HABITS OF WORMS. Chap. L

resembled an olive-oil flask in shape. These
concretions when broken are seen to be
more or less crystalline in structure. How
they escape from the gland is a marvel ; but
tliat 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
structure of the two anterior glands, and he
supposes 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 soluble 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 c(m-

<^nAP. I. CALCIFEllOUS GLANDS. 47

cretion, or one of only moderately large size
is dissolved in acid, mncli 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
manner. 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 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 lamellse.

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
nucleolus. They were only so far acted on
by acetic acid that the nucleus was thus
rendered more distinct. A very small con-
cretion 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

i8 HABITS OF WOKMS. Chap, h

multitude of the larger, free, nucleated cells,
aud 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 ascertained.

When an anterior gland contains several
minute concretions, some of these are generally
angular or crystalline in outline, while the
greater number are rounded with an irregu-
lar mulberry-like surface. Calciferous cells
adhered 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
lamellge ; and by such steps the formation of
the largest concretions could be followed.
Why the process regularly takes place in th©
two anterior glands, and only rarely in the
four posterior glands is quite unknown.
Morren says that these glands disappear

Chap. I. CALCIFEROUS GLANDS. 49

during the winter ; and I have seen some
instances of this fact, and others in which
either the anterior or posterior glands were
at this season so shrunk and empty, ttiat
they could be distinguished only with much
difficulty.

With respect to the function of the calci-
ferous glands, it is probable that they pri-
marily serve as organs of excretion, and
secondarily as an aid to digestion. Worms
consume 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 sub-
stances.'^ The ashes of a leaf of an acacia
have been known to contain as much as
Y2 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 calciferous glands are
well adapted for this purpose. The worms
which live in mould close over the chalk,
often have their intestines filled with this
substance, and their castings are almost white.

* De Vries, ' Landwirth. Jahrbiicher,' 1881, p. 77.

50 HABITS OF WORMS. Chap. L

Here it is evident that the supply of cal-
careous 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.

On the other hand, the following considera-
tions render it highly probable that the
carbonate of lime, which is excreted by the
glands, aids the digestive process under
ordinary circumstances. Leaves during their
decay generate 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, there-
fore, after they have been moistened and
triturated in the alimentary canal, be apt to

Chap. I. CALCIFEROUS GLANDS. 5i

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 digestive 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 pre-
paring the leaves for consumption, is likewise
alkaline. The acidity can hardly be due to
uric acid, as the contents of the upper 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 tlie
gizzard doubtfully so, while those of the in-
testine were distinctly acid at a distance of
5 cm. below the gizzard. Even with the
higher herbivorous and omnivorous animals,
the contents 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

52 HABITS OF WORMS. Chap. I.

" going on in the contents themselves. . . .
*' In Garni vora the contents of the coecum
" are said to be alkahne, and naturally the
*• amount of fermentation will depend largely
" on the nature of the food."*

With worms not only the contents of the
intestines, but their ejected matter or the
castings, are generally acid. Thirty castings
from different places were tested, and with
three or 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 following 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 neutralises the intestinal
acids. When worms were kept in pots filled

• M. Foster, 'A Text-Book of Physiology,' 2iid edit. 1878,
p 243.

CuAP. I. CALCIFEEOUS GLANDS. 53

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 castings.

The digestive fluid of worms resembles Id
its action, as already stated, the pancreatic
secretion of the higher animals ; and in these
latter, " pancreatic digestion is essentially
'' alkaline ; the action will not take place
" unless some alkali be present ; and the
^' activity of an alkaline juice is arrested by
" acidification, and hindered by neutraliza-
" tion."* Therefore it seems highly probable
that the innumerable calciferous cells, which
are poured from the four posterior glands
into the alimentary canal of worms, serve to
neutralise more or less completely the acids
there generated by 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 sufiSce to neu-
tralise 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

* M. Foster, Ibid. p. 200.

54 HABITS OF WOEMS. (Jiiap. I.

carried down to the posterioi parts of the
intestine, where these concretions would be
rolled about amongst the acid contents. Tho
concretions found in the intestines and in tho
castings often have a worn appearance, but
whether this is due to some amount of
attrition 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 may give some aid in this way ;
but I fully agree with Perrier that this must
be of quite subordinate 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,

Jidanner in whicli 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 — P^arth 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 ke]3t,
leaves were pinned down to the soil, and
at night the manner in which they were
seized could be observed. The worms always
endeavoured to drag the leaves towards their
burrows; and they tore or sucked o£P small
fragments, whenever the leaves were suffi-

56 HABITS OF WOllMS. C11A.P. II

ciently tender. They generally seized the
thin edge of a leaf with their mouths, between
the projecting 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 objects they acted in a wholly
different manner. The pointed anterior
extremity of the bod}^, after being brought
into contact with an object of this kind, was
drawn within the adjoining rings, so that it
appeared truncated and became 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 sliglit withdrawal ol
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
fiiinly together.* That under these circum-
Btances a vacuum was produced was plainly

* Claparedc remarks (' Zeitschrift fiir wissenschaft. Zoolog.
B. 19, 1869, p. 602) that the pharynx appears from its structuie
to be adapted for suction.

Ciup. II. THEIR MANNEE OF PEEHENSION. 57

seen on one occasion, wlien a large worm
lying beneath a flaccid cabbage leaf tried to
drag it away ; for the surface of the leaf
directly 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 anterior end of the body was momen-
tarily seen to be cup-formed. Worms can
attach themselves to an object beneath watei
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 nibbled 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 some-
times partly converted into skeletons. As
worms have no teeth and as their mouths
consist of very soft tissue, it may be pre-
sumed that they consume by means of suction
the edges and the parenchyma of fresh
leaves, after they have been softened by the

58 HABITS OF WORMS. Chap. IL

digestive fluid. They cannot attack such
sirong leaves as those of sea-kale or large
and thick leaves of ivy ; though one of the
latter after it had hecome 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-pedun-
cles, often decayed twigs of trees, bits of
paper, feathers, tufts of wool and horse-hairs
are dragged into their burrows for this pur-
pose. 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, feathers, &c,,
are never gnawed by worms. In a gravel
walk in my garden I found many hundred
leaves of a pine-tree (P. austriaca or nigin-
cans) drawn by their bases into burrows.
The surfaces by which these leaves are articu-
lated to the branches are shaped in as pecu-
liar a manner as is the joint between the leg-
bones of a quadruped ; and if these surfaces

Chap. II. PROTECTION OF THEIR BURROWS. 59

had been in the least gnawed, the fact would
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 con-
sumption. Where fallen leaves are abun-
dant, 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 betw^een the drawn-in leaves with

60 HABITS OF WORMS. Chap. IL

moist viscid earth ejected from their bodies,
and thus the 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, petioles,
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 in-
terested 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 burrows^ dragging the stones inwards
by the aid of their mouths, no doubt by
suction. ^' After .two nights some of the

Chap. IL PROTECIION OF THEIR BURROWS. 61

" holes liad 8 or 9 small stones over
"them; after four nights one had about
^' 30, and another 34 stones."* One stone
which had been dragged over the gravel-walk
to the mouth of a burrow weighed two
oances ; 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 donbtful. 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 moutli.
When gardeners wish to kill worms on a

• An account of her observations is given in the ' Gardeners
Chronicle,' March 28th, 1868, p. 324.

62 HABITS OF WORMS. Chap. II

lawn, it is necessary first to brush or rake
away the castings from the surface, in order
that the h'me-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-edgings 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 tbe bur-
rows from scolopenders, which^ according
to Hoffmeister, f are the bitterest enemies of
worms ? Or may not worms when thus pro-
tected be able to remain with safety with
their heads close to the mouths of their bur-
rows, 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

* London's ' Gard. Mag.' xvii. p. 216, as quoted in the ' Cata*
logue of the British Museum Worms,' 1865, p. 327.
t ' Familie der Regenwiirmer,' p. 19.

CSAP. 11. PEOTECTION OF THEIK BURKOWS. 63

radiation at niglit, from the surrounding
ground and herbage. I am inclined to be-
lieve in this latter view ; firstly, because 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 burrows with
leaves, apparently to prevent their bodies from
coming into close contact with the cold damp
earth. But the phigging-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 burrows, instead of piling them over
the mouths of their burrows, and they cannot
collect objects 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^

64 HABITS OF WORMS. Chap II.

the worms pertinaciously opened their bur-
rows almost every nighty 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 by worms in their manner
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 Avould probably
insert 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 espe-
cially desirable to do this in the case of plants
not natives to our country ; for although the
habit of dragging leaves into their burrows
is undoubtedly instinctive with worms, yel
instinct could not tell them how to act in
the case of leaves about which their pro-
genitors knew nothing. If, moreover, worms
acted solely through instinct or an unvary*

Chap. II. THEIR INTELLIGENCE. 65

ing inherited impulse, they would draw all
kinds of leaves into their burrows in the
same manner. If they have no such definite
instinct, we might expect that chance would
determine whether the tip, base or middle was
seized. If both these alternatives are ex-
cluded, intelHgence 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 methods
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
burrows 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 tbis case the tips pro-
jected from the burrows ; and 26 had been
seized near the middle, so that these had
been drawn in transversely and u-ere much
crumpled. Therefore 80 per cent, (always
using the nearest whole 'number) had been
drawn in by the tip, 9 per cent, by the base

B^ HABITS OF WORMS. Chap. IL

or footstalk, and 11 per cent. traDSversely or
by the middle. This alone is almost suffi-
cient 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 ftillen leaves of the common lime-tree,
which is almost certainly not a native of
England. These leaves are .much acumin-
ated towards the tip, and are very broad at
the base with a w^ell-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, trans-
versely or by the middle. These proportions
agree very closely, as far as the tip is con-
cerned, with those before given. But the per-
centage 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 in-
fluence in determining the manner in which
iime leaves are dragged into the burrows.

Chap. IL THEIR INTELIJGENCE. 67

The considerable proportioi], 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 after-
wards 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 gene-
rally fitted exactly ; and when there was
any difference, the basal half was a little the
narrower. It might, therefore, have been
expected that an almost equal number of
the>e leaves would have been drawn in by the
tip and base, or a slight excess in favour of
the latter. But of 73 leaves (not included m

t)8 HABITS OF WORMS. CnAP. IL

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, transversely. We here see that a far
larger proportion, 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 hav-
ing been drawn in by the base, by worms
having acquired the habit of generally draw
ing in leaves by their tips and thus avoid-
ing the foot-stalk. For the basal m.argin 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 contact
with the ground on each side of the burrow,
and would render the drawing in of the leaf
very difiicult.

Nevertheless worms break through their
habit of ai^oiding the footstalk, if this part
offers them the most convenient means for
drawing leaves into their burrows. The leaves

Chai'. ri. THEIR INTELLIGENCE. 69

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
becomes 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 varieties 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 bur-
rows more easily by the base or foot-stalk
than by the tip ; and this was partly due to
the shape of the leaf and in a less degree
to the curling in of the margins : 27 per

70 HABITS OF WORMS. .Chap. IL

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
sliape 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 exposed margins of
the free end will consequently 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 6Q per cent, had been
drawn in by the base or foot-stalk ; and 34
per cent, by the tip. In this case, there-
fore, the worms judged with a considerable
degree of correctness how best to draw the
withered leaves of this foreign plant into their
burrows; notwithstanding that they had to
depart from their usual habit of avoiding
the foot-stalk.

On the gravel-w^alks in my garden a very
large number of leaves of three species of
Pinus (P. austriaca, nigricars and sylvestri^)

Chap. IL THEIR INTELLIGENCE. 71

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
burrows were again well protected. These
leaves could not be dragged into the burrows
to any depth, except by their bases, as a
worm cannot 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 mentioned two or three excep-
tional cases. In order, therefore that worma

should do their work well, they must drag
6

72 HABITS OF WOEMS. Chap. IL

pine-leaves into their burrows by tlieir bases,
where the two needles are conjoined. But
how they are guided in this work is a per-
plexing 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 indif-
ferent 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 confinement often seized the
needles near the middle and drew them to-
wards the mouths of their burrows ; and one

CiiAP. II. THEIR INTELLIGENCE. 73

worm tried in a senseless manner to drag
tliem into the burrow by bending tbem.
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, how-
ever, they behaved very differently ; for as
soon as they touched the base of a pine-leaf,
this was seized, being sometimes completely en-
gulfed in their months, or a point very near
the base was se^'zed, 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
H 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
<vorm reared itself up and seized the base,
which was dragged into the mouth of the
burrow by bowing the whole leaf. On the
other hand, after a worm had seized the base

74 HABITS OF WORMS. Cuap. IL

of a leaf, this was on two occasions relin-
quished from some unknown 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 Scotc;h-
iir leaf, one needle of which was as long and
almost 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 obser-
vations 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 theso
were not real exceptions, as one was drawn
in for a very short distance, and the two
needles of the other cohered. Otlier pine-

Chap. IL THEIR INTELLIGENCD. 75

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 effectually. 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
general notion of the shape or structure of
pine leaves, and perceive that it is necessary
for them to seize the base where the two
needles are conjoined. But the following
cases make this more than doubtful. The

76 HABITS OF WORMS. Chap. IL

tips of a large number of needles of P. austriaca
were cemented together with shell-lac dis-
solved in alcohol, 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 121 leaves with
the tips cemented, which were drawn into bur-
rows, 108 were drawn in by their bases, and
only 13 by their tips. Thinking that the
worms might possibly perceive and dislike the
smell or taste of the shell-lac, though this
was very improbable, especially 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 leaves
thus treated 150 were drawn into burrows —
123 by the base and 27 by the tied tips; so
that between four and five times as many were

Chap. II. THEIR INTELLIGENCE. 77

drawn in by the base as by the tip. It is
possible that the short cnt-off ends of the
tliread 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 tlie leaves with tied and
cemented 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
sharpness of the points of the needles which
determines them ; for, as we have seen, many
leaves with the points cut off were drawn in
by their bases. We are thus led to conclude,
that with pine-leaves there must be something
attractive to worms in the base, notwithstand-
ing that few ordinary leaves are drawn in by
the base or footstalk.

Petioles, — We will now turn to the petioles
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

78 HABITS OF WORMS. Chap. U.

into the burrows on an adjoining gravel-
walk, lawn, and flower-bed. These petioles
vary from 2 J to 4 J 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
pomted, 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 7G 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
necessary in plugging up the burrows, the
proportion of those drawn in by the tip (130)
(io those drawn in by the base (48) was
rather less than three to one. That these

CuAP. II. THEIR INTELLIGENCE. 79

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,
i.n 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 afterwards a large
majority are drawn in by the pointed end, in
order to plug up the hole securely.

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 fieshy towards the base, whence they
taper gently towards the apex, which is a little
enlarged and truncated where the terminal
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

80 HABITS OF WORMS. Ciiai-. II.

cent, by the apex. This anomaly was how-
ever readily explained as soon as the thick
basal part was examined ; for in 78 out of 103
petioles, this part had been gnawed by worms,
just above the horse-shoe shaped articulation.
hi 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
ap the mouths of the burrows, but as food.
Even the narrow truncated tij)s 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 petioles out of their burrows ;
and then drag in fresh ones, either by
the base for food, or by the apex for plug-
ging up the mouth more effectually. Thus,
out of 37 petioles inserted by their tips,
5 had been previously drawn in by the
base, for this part liad been gnawed. Again,

Chap. IT. THEIE INTELLiaENCE. 81

I collected a handful of petioles lying loose
on the ground close to some plugged-up bur-
rows, 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
manner.

The petioles of Rohinia 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 drawn into the burrows of worms. Un-
fortunately 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

82 HABITS OF WOKMS. Chap. II

probable. Out of 121 petioles extracted from
burrows early iu 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 ot
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,
especially in the latter case, that none had
been drawn in as food. At this season, there-
fore, 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 difiS-
culty of plugging up a burrow with objects so
extremely thin 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 accident.

Triangles of paper, — Elongated trianghjy

Uhap. II. THEIR INTELLIGENCE. 83

were cut out of moderately stiff writing-paper,
which was 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
narrow or much acuminated.* As a check
on the observations presently to be given,
similar triangles in a damp state were 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 seized by the apex, the triangle
was drawn straight into the tube, with its
margins infolded; if seized at some little
distance from the apex, for instance at hall
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

• In tliese narrow triangles the apical angle is 9° 34', and the
basal angles 85° 13'. In the broader triangles the apical angle ia
19° !(/ and the basal andes 80° 25'.

84 HABITS OF WOllMS. Chap. II

more resistance to being drawn in. If seized
near tlie middle the triangle was doubled up,
with the apex and base left sticking out of the
tube. As the sides of the triangles were
ihree inches in length, the result of their
being drawn into a tube or into a burrow in
different ways, may be conveniently 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, 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

Chap. II. THEIR INTELLIGENCE. 85

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 tlie
chance of the former being drawn into a
burrow by suction, will be as 5 to 1, compared
with the apical part. The base offers 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 tri-
angles had been drawn into burrows by their
apical ends, that the tip had been doubled
back within the burrow for a length of
between ^^^th of an inch and 1 inch. Lastly,
the proportion between the margins of the basal
and apical parts is as 3 to 2 for the broad,
and 2^ to 2 for the narrow triangles. From
these several considerations it might certainlv
Lave been expected, supposing that worms
seized hold of the triangles by chance, that a
consldtrably larger proportion would have

86 HABITS OF WORMS. Chap. II.

been dragged into the burrows by the basal
than by the apical part; but we shall im-
mediately see how different was the result.

Triangles of the above specified sizes were
scattered on 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 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 v/ere
drawn in by tlie apex as by the base. If we

CuAP. II. TUEIR INTELLIGENCE. 87

consider the broad triangles 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 triangles, 65 pei
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 therefore conclude
that the manner in which the triangles are
drawn into the bm-rows 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 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 triangles
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 middle, and-

88 HABITS OF WORMS. Chap. II.

83 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 tlio
triangles were drawn in by the apex, not from
the w^orms having selected this end as the
most convenient for the purpose, but from
having first tried in other ways and failed.
This notion 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 noticed that the bases of those tri-
angles which 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

CiiAP. 11. THEIR INTELLIGEKCE. 89

times throngli my fingers. Owing to the
slime from the worms' bodies, the dirt was
not easily w^ashed off. We may therefore
conclude that if a triangle, before 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 con-
dition 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 nncreased
triangles, 14 were dirty at the base; but it
does 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 w^ere 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 actually trying to draw them into the

90

HABITS OF WORMS.

CiiAP. IT.

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 dirtied. We may therefore
infer — improbable as is tlie inference — that
worms are able by some means to judge
which is the best end by which to draw
triangles of paper into their burrows.

The per centage 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 follows : —

Drawn

into the Dravm

Drawn

Nature of Object.

burrows,
by or

in, by or

near the

in, by or

near the

near the

middle.

base.

apex.

Leaves of various kinds .

80

11

9

nf thp Tjimp I^'^'^al inar^ii ^f

blade broad, apex acumi-

nated ....

79

17

4

of a Laburnum, basal part of

blade as narrow as, or some-

times little narrower than

the apical part.

63

10

27

of the Rhododendron, basal

part of blade often narrower

than the apical part .

34

..

6«

of Pine-tr'^'^= n.>n«i«tincr nf two

needles arising from, a com-

mon base

100

Chap. II.

THEIR INTELIJGENCE.

91

Nature of Object.

Drawn
into the
burrows,

by or
near the

Drawn
in, by or:
near the

middle.

apex.

76

48-5

••

44

62

15

59

■ 25

65

14

Drawn

in, by ct

near the

base.

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

of the Ash, the thick basal

end often drawn in to serve
as food ....

of Robinia, extremely thin,

especially towards the apex,
so as to be ill-fitted fur
plugging up the burrows .

Triangles of paper, of the two sizes .

of the broad ones alone

• of the narrow ones alone

24

51-5

56
23
16
21

If we consider these several cases, we can
Lardly escape from the conclusion that worms
show some degree of intelligence in their
manner of plugging up their burrows. Each
particular object is seized in too uniform a
manner, 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 worms

92 HABITS OF WOKMS. Chap. II

are led by instinct to plug up their burrows ;
and it might have been expected that they
would have been led by instinct 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 sometimes be thought
to be thus directed ; for instance when dis-
placed leaves re-direct their upper surfaces
towards the light b}^ extremely complicated
movements and by the shortest course. With
animals, actions appearing due to intelligence
may be performed through inherited habit
without any intelligence, although aborigin-
ally thus acquired. Or the habit may have
been acquired through the preservation and
inheritance of beneficial variations of some
other habit ; and in this case the new habit
will have been acquired independently of
intelligence throughout the whole course
of its development. There is no a prion
improbability in worms having acquired
special instincts through either of these two
latter means. Nevertheless it is incredible
that instincts should have been developed
in reference to objects, such as the leaves or

Chap. II. THEIR INTELLIGENCE. 93

petioles of foreign plants, wholly unknown
to the progenitors of the worms which act
in the described manner. Nor are their actions
80 unvarying or inevitable as are most true
instincts.

As worms are not guided by special in-
stincts in each particular case, though pos-
sessing a general instinct to plug up their
burrows, 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 surprising 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 transversely to their
course, which could be easily drawn lougi-
fcudinally ; though after a time they gener-
ally act in a wiser mauner. M. Fabre
states* that a Sphex — an insect belong-
ing to the same highly-endowed order
with ants — stocks its nest with paralysed

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

9i HABITS OF WORMS. Chap. IL

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 the.se
were likewise cut off, the attempt to drag
its prey into the burrow was given up in
despair. The Sphex had not intelHgence
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 entering 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 to
seize minnows on the opposite side.* A cobra-
snake was seen by Mr. Layard f to act much
more wisely than either the pike or the Sphex ;

* Mobius, 'Die Bewegiingen der Thiere,' &c., 1873, p. 111.
t 'Annals and Mag. of N. Uistory,' series ii. vol. ix. 1852,
P. 333.

CiiAP. II. THEIR INTELLIGENCE. 95

it had swallowed a toad lying w^ithin a hole,
and could not withdraw its head ; the toad
was disgorged, and hegan to crawd 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, only when we see an
individual profiting by its own experience.
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 signally in this respect. Now if
worms try to drag objects into their burrows

96 HABITS OF "WORMS. Chap. II.

first in one way and then in another, until
they at last succeed, they profit, at least in
each particular instance, by experience.

But evidence has been advanced showing
t]iat worms do not habitually try to draw
objects into their burrows in many difierent
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
numbers; 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 apex as by the
base. It might have been thought that the
foot-stalks of leaves would have tempted the
worms as a convenient handle ; yet they are
not largely used, except when the base of the
blade is narrov/er than the apex. A large
number of the petioles of the ash are drawn
in by the base ; tut 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

CnAP. II. THEIR INTELLIGENCE. 97

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 pro-
bably acquire by touching it in many places
with the anterior extremity of their bodies,
which serves as a tactile organ. It may be
well to remember how perfect the sense of
touch becomes 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.

98 HABITS OF vVORMS. Cuap. II

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
alternative alone is left, namely, that worms,
although standing low in the scale of organiz-
ation, possess some degree of intelligence.
This will strike every one as very impro-
bable ; but it may be doubted whether we
know enough about the nervous system of
the lower animals to justify our natural dis-
trust of such a conclusion. With respect to
tlie small size of the cerebral ganglia, we
should remember ' what a mass of inherited
knowledge, with some power of adapting
means to an end, is crowded into the minute
brain of a worker-ant.

Means by which worms excavate their
burrows. — This is effected in two ways ; by
pushing away the earth on all sides, and by
swallowing it. In the former ca^e, the worm
inserts the stretched out and attenuated

Chap. II. EXCAVATION OF THEIE BUEEOWS. 99

anterior extremity of its body into any little
crevice, or hole ; and then, as Perrier re>
marks,* the pharynx is pushed forwards iiito
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 15 minutes between the sides
of the pot and the earth, which had been
moderately pressed dowu. On a third oc-
casion 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 minutes. On a fourth occasion six large
worms were placed on argillaceous mud
mixed with sand firmly pressed down, and
they disappeared, 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

* ' Archives de Zoolog exper.' torn. iii. 1874, p. 405.

100 HABITS OF WORMS. Chap. IL

generally entered the ground close to tlie
sides of the pot.

A pot was next filled with very fine ferru-
ginous sand, whicli 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 mas?
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 ot
the reddish sand and partly of black earth
brought up from beneath the mass. This
sand had been dug up from a considerable

Ch.ap. TI. excavation OF THEIR BUEEOWS. 101

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 ia
a field near my liouse the castings frequently
consist of almost pure chalk, which lies at only
a little depth beneath the surface ; and here
again it is very improbable 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 over-
lying 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
■jL 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 cast-
ing having weighed 33 grains. Whenever a
worm burrows to a depth of some feet in
undisturbed compact ground, it must form its

L02 HABITS OF WOllMS. Chap. U

passage by swallowing the earth ; for it is
incredible that the ground could yield on all
sides to the pressure 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
Arenicola marina, which throws up such a
profusion of castings on our tidal sands, and
which it is believed thus subsists, tliere ;ire
animals belonging to the most distinct classes,
which do not burrow, but habitually swallow
large quantities of sand ; namely the mollus-
can Oncliidium and many Echinoderms.*

If earth were swallowed only when worms
deepened their burrow^s or made new ones,
castings would be thrown up only occasion-
ally ; but in many places fresh castings may

* I state this on the authority of Semper, 'Eeisen im
Archii>l der rhilippinen," Th. ii. 1877, p. 30.

Chap. IT. EARTH SWALLOWED AS FOOD. 103

be seen every morning, and the amount
of earth ejected from the same burrow on
successive days is large. Yet worms do not
burrow to a great depth, except when tlie
weather 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 that the worms
should daily make fresh burrows in every
direction in the thin superficial layer of
dark -coloured humus, unless they obtained
nutriment of some kind from it. I have
observed a strictly analogous case in a field near
my house where bright red clay lay close
beneath the surface. Again on one part of
the Downs near Winchester the vegetable
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

i04 HABITS OF WORMS. Cuap. II.

another 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
several months with castings that they formed
an almost continuous layer ; and the large
number of worms which lived here must have
subsisted during these months on nutritious
matter 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
it contained was astonishingly great ; and
these crushed in the gizzards of worms may
largely aid in supporting them. When-
ever castings are thrown up in the greatest
number, few or no leaves are drawn into the
burrows ; for instance the turf along a hedge-
row, about 200 yards in length, was daily
observed in the autumn during several weeks,

Chap. II. EARTH SWALLOWED AS FOOD. 105

and every morning many fresli 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 subsisted 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 difference in the behaviour of
worms at different times, perhaps explains a
statement by Claparede, namely, that triturated
leaves and earth are always found in distinct
parts of their intestines.

Worms sometimes abound in places where
they can rarely or never obtain dead or
living leaves ; for instance, beneath the pave-
ment in well-swept courtyards, into which
leaves are only occasionally blown. My son
Horace examined a house, one corner of
which had subsided; and he found here in
the cellar, which was extremely damp, many
small worm-castings thrown up between the

106 HABITS OF WORMS. Chap. IL

stones witli which the cellar was paved ; and
in this case it is improbable that the worms
could ever have obtained leaves.

But the best evidence, known to me, of
worms subsisting for at least considerable
periods of time solely on the organic matter
contained in earth, is afforded by some facts
communicated to me by Dr. King. Near
Nice large castings abound in extraordinary
numbers, so that 5 or 6 were often found
within the space of a square foot. They
consist of fine, pale-coloured earth, containing
calcareous matter, which after having passed
through the bodies of worms and being dried,
coheres with considerable force. I have
reason to believe that these castings had been
formed by species of Perichaata, which have
been naturalised here from the East.* Thev

* Dr. King gave me some worms collected near Nice, whicli,
as he "believes, had constructed these castings. They were sent
to M. Perrier, who with great kindness examiaed and named them
for me: they consisted of Ferichceta affinis, a native of Cochin
China and of the Philippines ; P. Luzonica, a native of Luzon
in the Philippines ; and P. HouUeti, which lives near Calciitta.
M. Perrier informs me that species of Perichaata have been natural-
ized 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 worm? not endemic in the country, I waa

Chap. II. EAETH SWALLOWED AS FOOD.

107

rise like towers (see Fig. 2), with their sum-
inits often a httle hroader than their bases,

Fig. 2.

Towfer-Iike casting from near Nice, constructed of earth, voided
prooably by a species of Pericliseta : of natural size, copied from
a photograph.

sometimes to a height of above 3 and often
to a height of 2 J inches. The tallest of those

greatly surprised to see how closely they resembled castings sent
to me from near Calcutta, where it is known that species of
Perich£eta abound.

108 HABITS OF WORMS. Chap. II.

whicli were measured was 3*3 inch in height
and 1 in diameter. A small cylindrical pas-
sage 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 bur-
rows ; 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 worms having crawled down the ex-
terior surfaces of the towers in search of
leaves; and had they done so, tracks would
almost certainly have been left on the upper
part whilst it remained soft. It does not,
however, follow that these worms do not
draw leaves into their burrows during some
other season of the year, at which time they
would not build up their towers.

From the several foregoing cases, it can
hardly be doubted that worms swallow earth,
not only for the sake of making their bur-
rows, but for obtaining food. Hensen, how-
ever, concludes from his analyses of humus
that worms probably could not live on

Chap. U. DEPTH OF THEIK BURROWS. 109

ordinary vegetable mould, though he admits
that they might be nourished to some extent
by leaf-mould.* But we have seen that
worms eagerly devour raw meat, fat, and
dead worms ; and ordinary mould can hardly
fail to contain many ova^ larvae, and small
living or dead creatures, spores of crypto-
gamic 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, possess bladders
beautifully constructed for catching 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-

* * Zeitsclirift fiii- wissenscliaft. Zoolog.' B. xxviii. 1877
p. 3G4.

110 HABITS OF WOEMS. Chap. II.

continued dry weather and severe cold. In
Scandinavia, according to Eisen, and in Scot-
land, according to Mr. Lindsay Carnagie, the
burrows run down to a depth of from 7 to 8
feet ; in North Germany, according to Hoff-
meister, 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 observation, but I have often
met v/ith worms at depths of 3 to 4 feet.
In a bed of fine sand overlying the chalk,
which had never been disturbed, 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 Eoman Yilla,
which had not been disturbed for many
centuries, a worm w^as met with at a depth
of 66 inches ; and this was in the middle of
August.

The burrows run down perjoendicularly, or
more commonly a little obhquely. 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

Chap. II. CONSTRUCTION OF THEIR BURROWS. Ill

generally, or as I believe invariably, lined
with a thin layer of fine, dark-coloured earth
voided by the worms ; so that they must
dt first be made a little wider than their
ultimate diameter. I have seen several
burrows in undisturbed 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 httle 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 com
pact 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 of support ; and the burrow is rendered
w^ell 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

112 HABITS OF WORMS. Chap. II

unusual thickness. In tliis 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 noticed.
Many leaves of the Scotch-fir or pine {Pinus
sylvestris) were given to worms kept in con-
finement in two pots ; and when after several
weeks the earth was carefully broken up, the
upper parts of three oblique burrows were
found surrounded for lengths of 7, 4, and
3^ inches with pine-leaves, together with
fragments 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 inter-
stices between the pine-leaves ; and these
interstices were likewise plastered with the

Chap. II. CONSTEUCTION OF THEIR BUEROWS. 113

viscid castings voided 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 sli ghtly
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
animal easy and its egress difiScult or im-
possible. The skill shown by these worms
is noteworthy 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
manner 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

L14 HABITS OF WOEMS. Chap. 11

with tliem, mingled with fragments of other
kinds of leaves, drawn in to a depth of 4 or 5
inches. Worms often remain, as formeilj
stated^ for a long time close to the mouthg
of their burrows, apparently for warmth ;
and the basket-like structures formed of
leaves w^ould keep their bodies from coming
into close contact with the cold damp earth.
That they habitually 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 or several worms
pass the winter rolled up into a ball. Mr.
Lindsay Carnagie informed me (1838) that
he had examined many burrows over a stone-
quarry in Scotland, where the overlying
boulder-clay 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 ter-
minated in a rather large chamber, at a depth
of 7 or 8 feet from the surface. These cham-

Chap. II. CONSTRUCTION OF THEIR BURROWS. 115

bers contained many small sharp bits of ston^
and husks of flax-seeds. They must also
have contained living seeds, for on the follow-
ing 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 into a single
burrow, one of which had germinated.* 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 tliat it could
contain only seeds which had long lain
buried. It is probable that the little stones,

* ' Zeitsclirift fiir wissenschaft. Zoolosr.' B. xxviii. 1877, p. 350,

116 HABITS OF WOKMS. Chap. II.

as well as the seeds, are carried down from
the surface by being swallowed ; for a sur-
prising 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
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
ejected in little spurts, and when not so
liquid by a slow peristaltic movement. It is
not cast indifferently on any side, but with
some care, first on one and then on another
feide ; the tail being used almost like a troweb

Chap. II. EJECTION OF THEIR CASTINGS. 117

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 consider-
able time. In the case of the tower-hke
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 exhibited in
their construction. Dr. King also observed
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
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
protrudes, 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

118 HABITS OF WORMS. Chap. II.

the surface of the ground. When they can
find any cavity, aKS 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
experience serves, this is not the case, except-
ing 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 ;
for black streaks are thus left, and these are
conspicuous when passing through light-
coloured soil, and might be mistaken for
completely 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
})]aces 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^

CuAP. 11. THE COLLAPSE OF OLD BURROWS. 119

the whole ground would be first thickly
riddled with holes to a depth of about tea
inches, and in fifty years a hollow unsu}>
ported space, ten inches in depth, would be
left. The holes left by the decay of succes-
sively 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 with many small stones, it can
hardly be viscous 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 latei-ally, the surface rises ; durmg
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

120 HABITS OF WOEMS. Guap. II.

the movements were twice as great. These
observations were made by my son Horace,
who will hereafter publish an acco^mt 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 superincumbent soil which has
to be raised, than in the parts near the sur-
face. When the ground dries, the walls will
shrink a little and the burrows will be a
litl le enlarged. Their enlargement, however,
thiough the lateral contraction of the
ground, will not be favoured, but rather op-
posed, by the weight of the superincumbent
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

• Perrier, ' Archives de Zoolog. exp^r.' torn. 3, p. 378, 1874.

Chap. 11. THEIR WIDE DISTllIBUTJON. 121

abound in Iceland, and are known to exist
in the West Indies, St. Helena, Madagascar,
New Caledonia and Tahiti. In the Antarctic
regions, worms from Kerguelen Land have
been described 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.

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 respect to
distant lands. Worms throw up plenty of
castings in the United States. In Yenezuela,
castings, probably ejected by species 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
castings from the court-yard of his house,
having an area of 200 square yards. They
varied in bulk from half a cubic centimeter to
five cubic centimeters, and were on an average

122 HABITS OF WORMS. Chap. 1.1

three cubic centimeters. They were, therefore
of small size in comparison with those often
found in Enghmd ; for six large castings from
a field near my house averaged 16 cubic centi-
meters. 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
gigantic but very rare species is found tbere,
the burrows of which are sometimes even two
centimeters or nearly -J 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 enquiries from
gardeners and others, and from his own
observations, 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

Chap. IJ. THEIR WIDE DISTRIBUTION. 123

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
castings — 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 anything 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
fche 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

124

HABITS OF WOKMS.

Chap. II.

largest received by me was 3| inches in
height and 1-35 inch in diameter; another

Fig. 3.

A tower-like casting, probably ejected by a species of Perichgeta,
from the Botanic Garden, Calcutta : of natural size, engraved
from a photograph.

was only | inch in diameter and 2| in height.

Cdap. II. THEIR WIDE DISTRIBUTION. 125

In the following year, Mr. Scott measured
several of the largest ; one was 0 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 (li oz.) ; and one of them
weighed 44*8 grammes (or 2 oz.). All these
eastings were thrown up either in one night
or in two. Where the ground in Bengal is
dry, as under large trees, castings of a different
kind are found in vast numbers : these con-
sist of little oval or conical bodies, from about
the 2V ^^ rather above -^^ of an inch in
length. They are obviously voided by a
distinct species of worms.

The period during which worms neai
Calcutta display such extraordinary activity
lasts for only a little over two months
namely, during the cool season after the rains.
At this time they are generally found within
about 10 inches beneath the surface. Dunn<j
the hot season they burrow to a greater depth,
and are then found coiled up and apparently
hybernating. Mr. Scott has never seen them
at a greater depth than 2^ feet, but has heard

J2G HABITS OF WORMS. Cii\p. 11

of their liavii)g been found at 4 feet. Within
the forests, fresh castings may be found even
during the hot season. The worms in the
Botanic garden, during the cool and dij
season, draw many leaves and little sticka
into the mouths of their burrows, like our
English worms; but they rarely act in this
manner during 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
j)lace, on 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 inches in length,
and as thick as a man's little finger. These
castings were collected by Dr. King after
a period of 110 days without any rain; and
they must have been ejected either during
the north-east or more probably during
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

Chap. IL THEIR WIDE DISTRIBUTION. 127

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,

Fig. 4.

A casting from the Nilgiii Mountains in South India ; of
natural size, engraved from a photograph.

or above 3 oz. ; and the largest weighed
] 23*14 grammes, or 4^ oz., — that is above a
quarter of a pound ! The largest convolutions
were rather more than one inch in di imeter ;
but it is probable that they had subsided a little

128 HABITS OF WORMS. Chap. II.

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 tc
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
contained extremely few bits of rock, the
largest of which w^as 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 diffeient
climates.

CHAPTEE III.

TOE AMOUXT OF FINE EARTH BROUGHT UP llf
WORMS TO THE SURFACE.

Rate at which various ohjects strewed on tlie surface of srass-
fields are covered uj) by the castings of wdrms — The burial oi
a paved path — The slow subsicience of great stones left on the
surface — The number of worms which live within a given
space — The w.ight 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 subject
of this volume, namely the amount of earth
which is brought up by worms from beneatli
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 by
weighing the quantity brought up within a

[30 AMOUNT OF EARTH Chap. III.

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
tlie grasses, ^ inch in thickness, beneath
which, at a depth of 2^ inches (or 3 inches
from the surface), 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 ot
lime was either gravelly or of a coarse sandy
nature, and differed considerably in appear
ance 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
A^ere dug, that is after an interval of 3 or 4
years, the cinders formed a line of black spots
round the holes, at a deptli of 1 inch beneath
the surface, parallel to and above the white
layer of lime- Over another part of this field

Chap. III. BROUGHT UP BY WORMS. 131

cinders bad been strewed, only about balf-a-
year before, and tbese 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 everywhere at a greater depth than
before by nearly 1 inch, we will say by | of
an inch. Therefore mould to an averao:e
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 another
field, at a date which could not be positively
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 over-
lying 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 mould and the red clay fell apart. In a
third field, on which coal-cinders and burnt

132 AMOUNT OF EARTH Cuap. II [

marl had been strewed several times at un-
known 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 J inches beneath the sur-
face ; and below them at a depth in parts
of 9 J, and in other parts of 10^ inches there
were fragments of burnt marl. In a fourth
field two layers of lime, one al)ove the other,
could be distinctly traced, and beneath 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
enclosed, drained, ploughed, harrowed and
thickly 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 to half of the natural scale,
that the turf was ^ inch thick, beneath which
there was a layer of vegetable mould 2| inches

Chap. III. BROUGHT UP BY WOEMS.

133

thick. This layer did not contain fragments
of any kind ; but beneath it there was a layer
of mould, 1^ inch in thickness, full of fragments

hiihl

\i\tl\\\

Section, reduced to half the natural scale, of the vegetable 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.

of burnt marl, conspicuous from their red
colour, one of which near the bottom was an

134 AMOUNT OF EARTH Chap. IIL

inch in length ; and other fragments of coal-
cinders together with a few white quartz
pebhles. Beneath this layer and at a depth of
4| inches from the surface, the original black,
peaty, sandy soil with a few quartz pebbles
was encountered. Here therefore the frag-
ments of burnt marl and cinders 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 iragments were now found at from
4 to 5 inches beneath the surface. So that
in this interval of 6^- 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 21^
years, for in the closely underlying black,
peaty soil there were many worms. It is,
however, probable that formerly, whilst the
land remained poor, worms were scanty ; and
the mould would then have accumulated
slowly. The average annual increase of thick-
ness for the whole period is '19 of an inch.

Two other cases are worth recording. In
the spring of 1835, a field, which had

Ceap. III. BROUGHT UP BY WOEMS. 135

long existed 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 interval of about 2 J- years,
the sand formed a layer at a depth of | 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 annu-
ally brought to the surface. Immediately
beneath the layer of red sand, the original
substratum of black sandy peat extended.

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 years after the application of the marl,*

* 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, hut was now positive that thib was done in
10

136 AMOUNT OF EARTH Chap 1[I.

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
otlisr parts. This difference in depth de-
pended 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 un-
broken 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 other-
wise they would have been indiscriminately
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
planted, and the layer of marl-fragments was
now found 13 inches beneath the bottoms of
the furrows, and therefore probably 15 inches

1800, 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.

Jeap. hi. beought up by worms. ■ 137

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 32i years, would
have measured less than 15 inches, if the field
had always remained ns pasture, for the soil
would in this case have been much more
compact. The fragments of marl almost rested
on an undisturbed sub-stratum of wliite sand
with quartz pebbles ; and as this w^ould be
little attractive to worms, the mould would
hereafter be very slowly increased by their
action.

We w^ili now give some cases of the action
of worms, on land differing widely from
the dry sandy or the swampy pastures just
described. 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-
tooned and penetrated by many deep well-
like cavities.* During the dissolution of tiie

• 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

138 AMOUNT OF EABTH Cuap. HI.

clialk, the insoluble matter, including a vast
number of unrolled flints of all sizes, lias

circular space, several feet in diameter, sndt^enly 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 elsewheie. 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 clialk 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. 1 roughly
measured one which stood vertically, and it was of the same
length and of the same relative thickness as one of my arms.
These elongated flints must get placed in their upiight position,

Chap. III. BROUGHT UP BY WOEMS. 139

been left on the surface and forms a Led oi
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 -coloured 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 November, 1871, that is after an
interval of 29 years, a trench was dug across
this part of the field; and a line of white nodules
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

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-
aounted for by their mutual pressure, whilst the whole mass is
subsiding. 1 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.

1 40 AMOUNT OF EARTH Chap. III.

here been thrown np 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 9-i
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 11 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 ex-
amining the nodules w^ith 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 wholly dissolved, from pre-
senting a large surface to the carbonic acid
dissolved in the rain-water and to that gener-

Chap. III. BROUGHT UP BY WORMS. 141

ated in soil containing vegetable matter, as
well as to the hiimns-acids.* The projecting
corners would also, relatively to the other
parts, have been embraced by a larger num-
ber 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 at a depth of 7
inches beneath the surface, with another line
at a depth of 5 J inches parallel to the one
beneath. In another part of this field,
wdiich had formerly existed as a separate
one, and which it was believed had been
pasture-land for more than a century, trenches
were dug to see how thick the vegetable
mould was. By chance the first trench was
made at a spot where at some former period,

* S. W. Johnson, ' IIow Crops Foed,' 1870, p. 139

112 AMOUNT OF EARTH Chap. TIL

certainly more than forty years before, a
large hole had been filled up with coarse red
clay, flints, fragments of chalk, and gravel ;
«ind here the fine vegetable mould was only
from 4^ to 4f inches in thickness. In
another and undisturbed place, the mould
varied much in thickness, namely from 6^
to 8 1 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 were found in this field at
a depth of 26 inches) and during summer
when the weather is very dry.

Chap. III. BROUGHT UP BY WORMS. 143

A field, wliicti adjoins the one just de-
scribed, slopes in one part rather steeply
(viz., at from 10° to 15°); 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
vegetation, 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 disappeared before many
years had elapsed, as did every one of tlie
larger ones after a time ; so that after thirty
years (1871) a horse could gallop 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
aj>pearance of the field in 1842, the transfor-
mation was wonderful. This was certainly
the work of the worms, for though castings
were not frequent for several years, yet some
were thrown up month after month, and

114 AMOUNT OF EARTH Chap. Ill

tljese gradually increased in numbers as tlio
pasture improved. In the year 1871 a
trench was dug on the above slope, and tlie
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 accur-
ately. 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 m.uch 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
Bt] iking, when I examined in Knole Park
a dense forest of lofty beech-trees, beneath
which nothing grew. Here the ground was
thickly strewed with large naked stones, and

CuAP. IIL BEOUGHT UP BY WOHMS. 145

worm-castings were almost wholly absent.
Obscure lines and irregularities on the sur-
face indicated that the land had been cul-
tivated 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. Anyhow 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
striking.

A narrow path running across part of my
lawn was paved in 1843 with small flag-
stones, set edgeways ; but worms threw up
many castings and weeds grew thickly be-
tween 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 lawn was mowed.
The path soon became almost covered u]),
and after several years no trace of it wais

14G AMOUNT OF EAKTH Chap, llh

lef^. On removing, in 1877, the thin over*
lying 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, eighteen years before ; and on the
clean-cut perpendicular 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, narrow 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 statesy that crushed bones had been
thickly strewed over a field ; and " some years
" afterwards " these were found " several inches
''below the surface, at a uniform depth."
Worms appear to act in the same manner in
New Zealand as in Europe ; for Professor J.

* ' Nature,' November 1877, p. 28.

♦ * Proc. Phil. Soc' of Manchester, 1877, p. 247,

Chap III. BROUGHT UP BY WORMS. 147

von Haast has described * a section near the
coast, consisting of mica-schist, " covered by
"5 or 6 feet of loess, above which about ] 2
" inches of vegetable soil had accumulated.'*
Between the loess and the mould there was
a layer from 3 to 6 inches in thickness,
consisting of "cores, implements, flakes, and
*' chips, all manufactured from hard basaltic
"rock." It is therefore probable that the
aborigines, at some former period, had left
these objects on the surface, and that they
had afterwards 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
pasture-land, after a time disappear, or, as
they say, work themselves downwards. How
powdered lime, cinders, and heavy stones,
can work down, and at the same rate,
through the matted roots of a grass-covered
surface, is a question which has probably
never occurred to them.f

• * Trans, of the New Zealand Institute,' vol. xii., 1880, p. 152.

t 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 beUef that it has some tendency to sink. He adds : " Some

118 GREAT STONES Cn^r. Ill,

The Sinking of great Stones through the
Action of Worms. — When a stone of large
size and of irregular shape is left on the
surface of the ground, it rests, of conrso,
on the more protuberant parts ; but worms
soon fill up with their castings all the hollow
spaces on the lower side ; for, as Hensen re-
marks, 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 ex-
cavated directly beneath the stone after a
time collapse, the stone sinks a little.* Hence
it is, that boulders which at some ancient

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 jpartially followed. By means of Mr. Darwin's
observations, I think the prejudice will be removed."

* This conclusion, which, as we shall immediately see. is fully
justifipd,isofsome little importance, as the so-called bench-stones,
which sun-eyors fix in the ground as a record of their levels,
may in time become false standards. My son Horace intends al
»ome future period to ascertain how far this has occurred.

CiiAP. III. UNDERMINED BY WORMS. 149

period have rolled down from a rocky moun-
tain or cliff on to a meadow at its base, are
always somewliat embedded in the soil ; and,
when removed, leave an exact impression of
their lower surfaces in the nnder-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 here-
after be of some use. An old workman re-
membered 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 covered with turf
and mould. The two largest of these stones
had never since been moved ; nor 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

150 GREAT STONES Chap. III.

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 ibund ; and this
could have yielded very little, if at all, to
the \veight 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 beneath the gen(?ral level,
and the upper surface projected about 8
inches above this level, or about 4 inches
above the sloping border of turf. After tl.e
removal of the stone it became evident that
one of its pointed ends must at first have
stood clear above the ground by some inches,
but its upper surface was now on a level
v^ith the surrounding turf. When the stone
v/as removed, an exact cast of its lowei

Chap. III. UNDERMINED BY WORMS. 151

side, forming a shallow crateriform hollow,
was left^ the inner surface of which consisted
of fine black mould, excepting where the
more protuberant parts rested on the brick-
tubbish. A transverse section of this stone,
together with its bed, drawn from measure-
ments made after it had been displaced, is
here given on a scale of ^ inch to a foot
(Fig. 6). The turf-covered border which

irmtP^^ . ^J:!ii^l ^ ^-v

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 represented. Scale
i inch to one foot.

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. The whole stone had sunk in the
thirty-fi.ve years, as far as I could judge,

about 1^- inch ; and this must have been due
11

152 GREAT STONES Chap. Ill

to the brick-rubbish beneath the more pro-
tuberant parts having been undermined by
worms. At this rate the upper surface of the
stone, if it had been left undisturbed, would
have sunk to the general 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 over 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
surface was nearly flat, so that the worms
must soon have been compelled to eject their
castings 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 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

Chap. III. UNDERMINED BY WOEMS. 153

place it was as much as 5^. Its average
height close to the stone was prohably about
3 inches, and it thinned out to nothing. If
so, a layer of fine earth, 15 inches in breadth
and 1^ inch in average 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 sufficient 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 border down
to the level of the field. Some fresh castino-s

o

were seen close to the stone. Nevertheless,
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
their establishment the worms had decreased
in number.

The third stone was only about half as

154 GREAT STONES Chap. TIT.

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
moderately recent time, for it now lay at
some distance from the two other 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 con-
clusion, 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 beneath this stone, and on
digging a hole w^here it had lain, several
burrows and worms were found.

At Stonehenge, some of the outer Druidical
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
borders of turf, on which recent castings were
seen. Close to one of these fallen stones,
which was 17 ft. long, 6 ft. broad, and 28. |
inches thick, a hole was dug ; and here the
vegetable mould was at kast 9^ inches in
thickness. At this depth a flint was found,
and a little higher up on one side of the hole

Chap. III. UNDERMINED BY WORMS. 155

a fragment of glass. The base of the stone
Jay about 9^ incbes beneath the level of the
surrounding ground, and its upper surface
1 9 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.
Ai a distance of 8 yards from the stone, the
mould was only 5 J inches in thickness (with
a piece of tobacco pipe at a depth of 4 inches),
and this rested on broken flint and chalk
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

156 GREAT STONES Chap. III.

contour of the projecting parts and of the ad-
joining ground, which was not quite level,
was thus ascertained, as shown in the ac-
companying diagram (Fig. 7) on a scale of

Grass

Fig. 7.

Section thrmigh one of the fallen Dmidical stones at Stonehenge,
showing how much it had sunk into the ground. Scale h inch
to 1 foot.

^ 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 2i 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, 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

Chap. III. UNDEKMINEB BY WOEMS. 157

of the land where worms abound soon gel
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 embedded in
the mould at various depths beneath the
surface. When the same field was re-ex-
amined 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 w^orked; the result
being, however, partly the effect of the wash-
ing down of the fresh castings by rain. The
specific gravity of the objects does not affect
their rate of sinking, as could be seen by
porous cinders, burnt marl, chalk and quartz
pebbles, having all sunk to the same depth
within the same time. Considering the
nature of the substratum, which at Leith Hill

L58 NUMBER OF WORMS. Chap. III.

Place was sandy soil including' many bits of
rock, and at Stonehenge, clialk-rubble with
broken flints; considering, also, the presence
of the turf-covered sloping border of mould
round the great fragments of stone at botb
tliese places, their sinking does not appear to
have been sensibly aided by their weight,
though this was considerable.*

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

» 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,
FiCli 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
i'lstances the Tower of Pisa, but adds that it was founded on
" vlense clay."

t ' Zoitschrift fiir wissensch. Zoolog.' Bd. xxviii., 1877, p. 354

Ceap III. KUMBER OF WORMS. 159

land, or 53,767 in an acre. This latter
Dinnber of worms would weigh 356 pounds,
raking Hensen's standard of the weight of a
?gingle worm, namely, one gram. It should,
however, be noted that this calculation is
founded on the numbers found in a garden,
and Hensen believes that worms are here
twice as numerous as in corn-fields. The
above result, astonishing 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,* in the hope of making vinegar,
but the vinegar proved bad, and the barrels
were upset. It should be premised 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 considerable body of
;vater in which worms were immersed, in-
variably killed them quickly. On the morn-
ing after the barrels had been upset, " the
'' heaps of worms which lay dead on the

• See Mr. Dancer's paper in ' Proc. Phil. Soc. of Manchester,
1877, p. 248.

160 WEIGHT OF EARTH Chap. IIL

" 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 evi-
dence 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 14i square feet, that is, nine in
2 square feet. Bat the burrows are some-
times much more numerous, for when digging
in ^ grass-field near Maer Hall, I found a
cake of dry earth, as large as my two open
hands, which was penetrated by seven bur-
rows, 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 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

Chap. III. BROUGHT UP BY WORMS. 161

making deep burrows. This is rendered
almost certain by the following weights of the
castings thrown up at tlie 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 buerow.

Ounces.

(1.) Down, Kent (sub-soil red clay, full of flints, over-\
lying the chalk). The largest casting which 1 1
could find on the flanks of a steep valley, the? 3*98
sub-soil being 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
poor pasture land at the bottom of the valley
mentioned under (1.)

(3.) Down. — A large casting, but not of unusual size, j

from a nearly level field, poor pasture, laid down in \ 1'22
grass about 35 years before.. .. .. .. )

(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 [
during a considerahle length of time to rain .. )

(5.) Near Nice in France. — Average weight of 121
castings 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 pro-
tected by shrubberies, near the sea ; soil sandy and
calcareous ; the.se castings had been exposed for some
time to rain, before being collected, and must have
.ost some weight by disintegration, but they still re-
tained tV.rir form

3-8';

1-37

162 WEIGHT OF EARTH Chap. Ill

"Weight of the Castings accumulated at the mouth
OF A SINGLE BuRROW — continued.

Dunces.
(6.) The heaviest of the above twelve castings .. 1*76

(7.) Lower Bengal. — Avtiage weight of 22 castings,!

collected by Mr. J. Scott, and stated by him to havei 1*24
been thrown up in the course of one or two nights )
(8.) The heaviest of the above 22 castings .. ,. 2 '09

(9.) Nilgiri Mountains, S. India ; average weight of^

the 5 largest castings collected by Dr. King. They I q.ik
had been exposed to the rain of the last monsoon, j
and must have lost some weight .. .. ..J

(10.) The heaviest of the above 5 castings .. .. 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 Nilgiri moun-
tains one easting even exceeded this latter
weight. The largest castings in England
were found on extremely poor pasture- land ;
and these, as far as I have seen, are generally
larger than those on land producing a rich
vegetation. It would appear that worms
];ave to swallow a greater amount of earth
0J1 poor than on rich land, in order to obtain
Bufficient nutriment.

With respect to the tower-like castings

Chap. III. BROUGHT UP BY WORMS. 163

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
weighted together 7^ ounces ; so that the
weight of those on a square yard would
have been 4 lb. 3 J 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 appearance in reference to the
rainy and dry periods near Nice, within the
previous five or six months ; they weighed
9^ oz., or 5 lb. 5^ oz. per square yard. After
an interval of four months, Dr. King collected
all the castings subsequently ejected on the
same square foot of surface, and they weighed
2^oz., or lib. 6 J oz. 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

164 WEIGHT OF EARTH Chap. TIL

yard ; and tins 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 before, 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 whole inter-
vening period. I had examined the same
part of the field shortly before it was rolled,
and it then abounded with fresh castings.
Worms do not work in dry weather during

Chap. III. BKOUGIIT UP BY WORMS. 165

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 estimate
' — 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
wdiole surface to be equally productive in
castings.

In the foregoing cases some of the
necessary data had to be estimated, but in
the two following cases the results are much
more trustworthy. A lady, on whose ac-
curacy I can implicitly rely, offered to collect
during a year all the castings thrown up on
two separate 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 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

163 WEIGHT OF EARTH Chap. IH

particles were thus o^ten lost. The lady also
occasionally left home for a week or iwo^ 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 castings on it, was rather unfavourable for
the existence 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

Chap. III. BROUGHT UP BY WORMS. 167

mould together with the turf was ouly 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
existing 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 J 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 un-
enclosed 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
favourable nor the reverse for worms ; but I
have often noticed that castings are especially
abundant on common land, and this may,
perhaps, 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

12

168 WEIGHT OF EARTH Chap. III.

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 collection
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.

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 aoout 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 terrace at

Chap. III. BKOUGHT UP BY WOEMS. 169

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 mouldy which
castings ejected during a year would form if
uniformly spread out. — As we know from
the two last 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 uni-
formly over a square yard. The dry castings
were therefore broken into small particles,
and whilst being placed in a measure were
well shaken and pressed down. Those col-
lected on the Terrace amounted to 124*77
cubic inches ; and this amount, if spread out
over a square yard, 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

170 THICKNESS OF THE MOULD Chap. III.

nearly so compact a mass as vegetable mould,
though each separate particle was very
compact. Yet mould is far from being com-
pact, as is shown by the number of air-
bubbles which rise up when the surface is
flooded with water. It is moreover pene-
trated by many fine roots. To ascertain ap-
proximately by how much ordinary vegetable
mould would be increased in bulk by beiiig
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 ^ of its original bulk, judging from
exterior measurements alone. It was then
triturated and partly reduced to powder, in the
same manner as the castings had been treated,
and its bulk now exceeded (notwithstanding
shrinkage from drying) by -^ that of the
original block of damp mould. Therefore the
above calculated 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 yV» ^^^^ ^^^^ ^^i^^
reduce the layer to '09 of an inch, so that a

Chap. III. ANNUALLY ACCUMULATED. 171

layer '9 inch in thickness would be formed in
the course of ten years. On the same prin-
ciple 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 thickness in the former case
would amount to nearly 1 inch, and in the
second case to nearly IJ 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
become buried (as described in the early part
of this chapter), we will give the following
summary : —

BlTMMARY 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 14| years on the surface
of a dry, sandy, grass-field near Maer Hall, amounted to 2*2
inches in 10 years.

The accumulation during 21^ 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 durmg 30 years on the side of a valley over

172 THICKNESS OF THE MOULD Chap. III.

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 brouglit
to the surface during 10 years is somev^hat
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 wlien
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 the castings that were collected,
namely, the fine earth brought up to the
surface by burrowing larvge and insects, espe-
cially by ants. The earth brought up by moles
generally has a somewhat different appearance
from vegetable mould ; but after a time would
not be distinguishable from it. In dry coun-
tiies, moreover the wind plays an important
part in carrying dust from one place to another,
and even in England it must add to the mould

Chap. HI. ANNUALLY ACCUMULATED. 173

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
summary 15 tons as the weight of the castings
annually thrown up on an acre of land, each
worm must annually eject 20 ounces. A fuli-
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 20 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,

174 THICKNESS OF THE MOULD Chap. HI.

which is usually from 4 or 5 to 10 and even
1 2 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 barrow 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
agencies at work which carry away to a
lower level some of the finest earth which is
continually being brought to the surface by
worms. How great a thickness vegetable
mould ever attains, 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 two last chapters we
shall see that the soil is actually increased,
though only to a small degree, through the
agency of worms; but their chief work ia
to sift the finer from the coarser particles, to

Chap. III. ANNUALLY ACCUMULATED. 175

mingle the whole with vegetable debris, and
to saturate it with their intestinal secretions.

FinaJlj, 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 cast-
ings ejected within a known time on a measured
space — will hereafter, as I believe, doubt that
worms play an important part in nature.

CHAPTER IV.

THE PART WHICH WORMS HAVE PLATED IX
THE BURIAL OF ANCIENT BUILDINGS.

The accumulation of rubbisli 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 tesselated floors and walls by worms — Subsidence of
the floors — Thickness of the mould — The old Roman city of
Wroxeter — Thickness of the mould — Depth of the foundations
of some of the Buildings — Conclusion.

Archaeologists are probably not aware how
much tbey ow'G to worms for the preservation
of many ancient objects. Coins, gold orna-
ments, 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 w^ill thus be safely preserved, until
the land at some future time is turned up
For instance, many years ago a grass-field

Chap. IY. OF ANCIENT BUILDINGS. 177

was 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. Blakeway, 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 remains 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 underlie many cities,
such as Rome, Paris, and London, the lower
ones being of great antiquity, are not here
referred to, as they have not been in any
way acted on by worms. When we con-
sider 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 scavenger
was neglected, a comparatively small amount

178 BURIAL OF THE REMAINS Chap. IV

was carried away, we may agree with
Elie de Beaumont, who, in discussing this
subject, 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 2| 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
believed 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 fragments
of pottery, other objects, and coins of several

• * Le9ons de G^ologie pratique,' 1845, p. 142.

\ 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. 179

Roman emperors, datiug from 133 to 361, and
perhaps to 375 A.D., were likewise found.
-Also a half-penny of George 1., 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
inhabited. 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 7° ; and one of the two trenches,
shown in the accompanying section (Fig. 8)
was at the upper or eastern end. The
diagram is on a scale of -^q 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 mould over the floor

180

BURIAL OF THE REMAINS Chap. IV.

Section throngli the foundations of a buried Roman yilla at
Abinger. A A, vegetable mould ; B, dark earth full of stones,
]3 inches in thickness ; C, black mould ; D, broken morfar ;
E, black mould ; F F, undisturbed sub-soil ; G, tesserse ; H.
concrete I, nature unknown ; W, buried wall.

Chap. IV. OF ANCIENT BUILDINGS. 181

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 1 3 inches. After
the mould had been removed, the floor
appeared as a whole moderately level ; but it
sloped in parts at an angle of 1°, 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 w^as 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 existence 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
14 inches in thickness; it rested on a mass (B'^

182 BURIAL OF THE REMAINS Chap. IY.

23 inches thick of blackish earth, including
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,
argillaceous 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 thickness, beneath which was the
undisturbed sand. Most of this earth had
probably been washed down from the upper
part of the field, and the fragments of

CuAP. IV OF ANCIEKT BUILDINGS. IS.S

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 haxe
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 surrounding broken walls must have been
covered by at least 4 inches of soil, for other-
wise 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 tesseras 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
by worms ; and although the overlying fine
mould closelv resembled that which in many

13

184 BURIAL OF THE REMAINS Chap. IV

places has certainly been accumulated bj
worms, yet it seemed hardly possible that this
mould could have been brought up by wormp
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 cast-
ings. 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 conclu-
sion 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 pene-
trated 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 thi-ough tho
softer parts of the naked concrete, or between
the interstices of the tesserge. On the third
morning twen+y-five burrows were counted ;

Chap. IV. OF ANCIENT BUILDINGS. 185

and hj 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 activity
of worms, and the weather had lately been
Lot and dry, so that most of the worms now
lived at a considerable depth. In digging
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 Gfi^
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 next seven weeks, by which
time the worms in the surrounding country
were in full activity, and were work-

186 BUKIAL OF THE REMAINS Cha?. TY

ing near the surface. It is very improbable
that worms should have migrated from the
adjoining field 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 tlie work of the
former inhabitants of the space. I will now
give a few extracts from Mr. Farrer's notes.

Aug. 2'jth, 1877; that is, 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
defaced.

Sept. 12th. — During the last six days, the
worms have not been active, though many
castings have been ejected in the neighbour

Chap. IV. OF ANCIENT BUILDINGS. 187

ins: fields ; but on tliis 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 wdien a fresh barrow is sjDoken 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 w^hen
no earth was ejected from them. I have
often observed the same fact, and generally
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 httle
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 w^ere all
defaced.

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

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

188 BUEIAL OF THE REMAINS Chap. IV.

Sept. 18tb ; 43 fresli holes, 8 castings; all
defaced.

The number of castings on the surrounding
fields was now very large.

Sept. 19t]i ; 40 holes, 8 castings; all
defaced.

Sept. 22nd ; 43 holes, only a few fresh
castings ; all defaced.

Sept. 23rd ; 44 holes, 8 castings.

Sept. 25th ; 50 holes, no record of the
number 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 concrete 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
mortar 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, Rve days after the
ruins had been exposed, he observed four

Chap. IV. OF ANCIENT BUILDINGS. 189

open burrows on the broken summit of the
eastern wall (W in Fig. 8) ; and, on Septem-
ber 15th, other burrows similarly situated
were seen. It should also be noted that in
the perpendicular side of the trench (which
was much deeper than is represented in
Fig. 8) three recent burrows were seen, which
ran obliquely far down beneath the base of
the old wall.

AYe thus see that many worms lived beneath
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 wa?<
su£6.ciently decayed to allow them to penetrate
it ; and even before that period they would
have lived beneath the floor, as soon as it
became pervious to rain, so that the so 1
beneath 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,
perhaps for a thousand years. If the burrows

190 BUEIAL OF THE EEMAINS Chap. IV

beneath the floor and walls, which it is prob-
able were formerly as numerous as they now
are, had not collapsed in the course of time
in the manner formerly explained, the under-
lying earth would have been riddled with pas-
sages like a sponge ; and as this was not
the case, we may feel sure that thev have
collapsed. The inevitable result of such col-
lapsing during successive centuries, will have
been the slow subsidence of the floor and of the
walls, and their burial beneath the accumu-
lated worm-castings. The subsidence of a
floor, whilst it still remains nearly horizontal,
may at first appear 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 beneath 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 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
imdermined, and would have sunk, like the great

Chap. IV. OF ANCIENT BUILDINGS. 191

stones at Leith Hill Place and Stonehenge,
for the soil would have been damp beneath
them. But the rate of sinking of the dif-
ferent 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 therefore
have tended to subside at nearly the same
rate as the floor. But this would not have
occurred 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 villa,
in some places to a thickness of 16 inches,
was brought up from below by worms. P'rom
facts hereafter to be given there can be no
doubt that some of the finest earth thus
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

192 BURIAL OF THE REMAINS Chap. IV

earth brought up by iDsects, and some accu-
mulation 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 thick-
ness 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 two
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 pave-
ment had thus become slightly concave along
the middle ; but there w^as no subsidence at
the end close to the house. Mr. Ramsaj^

Chap. IV. OF ANCIENT BUILDINGS. 193

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 altogether 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. Con-
sidering all these circumstances, 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 to the house, where the ground
beneath would have been kept nearly dry.

Beaulieu Abbey, Hampshire. — This abbey
was destroyed by Henry YIIl., and there
now remains only a portion of the southern
aisle-wall. It is believed that the king had
mobt of the stones carried away for building

194 BUEIAL OF THE REMAINS Chap. IV

a castle ; and it is certain tliat they have been
removed. The position of the nave-transept
was ascertained not long ago by the
foundations having been found ; and the
|)lace 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
tesselated pavement of the abbey was thus
discovered. These holes were afterwards
surrounded by brickwork, and protected by
trap-doors, so that the pavement might be
readily inspected and preserved. When my
son William examined the place on January
5, 1872, he found that the pavement in the
three holes lay at depths of 6|, 10 and Hi
laches beneath the surrounding turf-covered
surface. The old guardian asserted that he
was often forced to remove worni'Castings
from the 23avement ; and that he had done

Chap. IV. OF ANCIENT BUILDINGS. 195

SO about six montlis before. 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 ha.l
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 compared with wliat, 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 castings 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 re-
spects very unfavourable for the accumulation
of even a moderate amount of castings. The
tiles are rather large, viz., about 5i inches
square, and the mortar between 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 consequence con-
sisted in large part (viz., in the proportion
of 19 to 33) of particles of mortar, grains of

19(3 BURIAL OF THE REMAINS Chap. IV.

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 con-
crete on which tiles had once rested. The
fine mould beneath the turf on the sides of
the several holes, varied in thickness from
only 2 to 2 J inches, and this rested on a layer
from 8 a to above 11 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 from the
abbey, the fine vegetable mould was 11 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

Chap. IV. OF ANCIENT BUILDINGS. 197

filled up the interstices in the overlying
rubbish 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
tlje 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
columns were constructed must have been
removed from beneath the former level of
the floor.

Chedu:orth^ 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
suspicion seems ever to have been enter-
tained that ancient buildings lay buried here,
until a gamekeeper, in digging for rabbits,

198 BURIAL OF THE REMAINS Chap. IV.

encountered some remains.* But subse-
quently the tops of some stone walls were de-
tected 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 Constant! ne family.
My sons Francis and Horace visited the
place in November 1877, for tlie sake of
ascertaining what part worms may have
played in the burial of these extensive re-
mains. Bat the circumstances were not
favourable for this object, as the ruins are sur-
rounded on three sides by rather steep banks,
do^vn which earth is washed during rainy
weather. Moreover most of the old rooms
have been covered with roofs, for the pro-
tection of the elegant tesselated pavements.

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

* Several accounts of these ruins have been published ; the
Dest 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
nuckman has likewise published a pamphlet, * Notes on the
Rtimau Villa at Chcdwcrth,' 2nd edit. 1873: Cirencester.

Chap. IV. OF ANCIENT BUILDINOS. 199

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, v^m
found, resting on the undisturbed sub- soil oi
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
superincumbent 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 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.

JBrading, Isle of Wight. — A fine Roman
villa was discovered here in 1880 ; and by
the end of October no less than 18 chambers
Mad been more or less clenrud. A coin dated

14

200 BURIAL OF THE REMAINS Chap. IV.

337 A.D. was found. My son William visited
the place before the excavations were com-
pleted ; and he informs me that most of tho
floors were at first covered with much rubbish
and fallen stones, having their interstices
completely filled up with mould, abounding
as the workmen 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 overlying earth was only
2 ft. 6 in. thick ; and after this had been re-
moved, 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 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
foundation of very hard red sand, into which
worms could hardly burrow. The mortar,
however, between the stones of the walls of

Chap. IV. OF ANCIENT BUILDINGS. 201

a hypocaust was found by my son to have
been penetrated by many worm-burrows.
The remains of this villa stand on land which
slopes at an angle of about 3° ; and the land
appears to have been long cultivated. There-
fore 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 pre-
served than any other remains of the kind
in England. A broken wall, in most parts
from 15 to 18 feet in height and about 1^
mile in compass, now surrounds a space of
about 100 acres of cultivated land, on which
a farm-house and a church stand.* Formerly,
when the weather was dry, the lines of the
buried walls could be traced by the appear-
ance of the crops ; and recently very exten-
sive excavations have been undertaken by
the Duke of Wellington, under the superin-
tendence of the late Kev. J. Gr. Joyce, by
which means many large buildings have been

* These details are taken from the * Penny Encyclopa3dia,
article, Hampshire.

202 BURIAL OF THE REMAINS Chap. IV

discovered. Mr. Joyce made careful coloured
sections, and measured the thickness of each
bed of rubbish, whilst the excavations 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 wnthin the walls during this long
period. It appears to have been destroyed
by fire, and most of the stones used in the
buildings have since been carried away.
These circumstances are unfavourable for as-
certaining the part which w^orms have played
in the burial of the ruins; but as careful
sections of the rubbish overlying an ancient
town have seldom or never before been made
in England, I will give copies of the most
characteristic portions of some of those made
by Mr. Joyce. They are of too great length
to be here introduced entire.

An east and west section, 30 ft. in length,
was made across a room in the Basilica, now

Chap. IV. OF ANCIENT BUILDINGS.

203

called the Hall of the Merchants (Fig. 9).
The hard concrete floor, still covered here
and there with tesserae, was found at 3 ft»

Fig. 9.
Section within a room in the Basilica at SilcLester. Scale ^.

204 BURIAL OF THE REMAINS Chap. IV.

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 w^as covered by a thin
white layer of decayed stucco or plaster,
above which was a mass, presenting a singu-
larly 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. This bed was capped by
fine vegetable mould, 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 surface of the level field.

A section across the middle of another hall
in th3 Basilica, 32 feet 6 inches in length,
called the (Evarium, is shown in Fig. 10.
It appears that we have here evidence of twc

CUAP. IV.

OF ANCIENT BUILDINGS.

205

fires, separated by an interval of time, during
which the 6 inches of " mortar and concrete

Ms .2

^ 6 03

F \i

'I

HI H

^^^B ■) Bu

^H^'E

^B ^K

«

^V^ K

H^L

^■^'If

^^^^K ^mx

H ^ m-'

^H ^VtA

B 1 |oK .

■ If^

■^cpI^*|

I ^^f4

■ ^ K

1 K^^

■ V/l ^Klk a/S^

^ KB^iffi^

Fig. 10.
Section within a hall in the Basilica at Silchester. Scale 3^-

206 BURIAL OF THE REMAINS Chap. IV.

with broken tiles " was accumulated. Be-
neath one of the layers of charred wood, a
vahiable rehc, a bronze eagle, was found ;
and this shows that the soldiers must have
deserted the pkce in a panic. Owing to the
death of Mr. Joyce, I have not been able to
ascertain beneath which of the two layers the
eagle was found. The bed of rubble overly-
ing 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 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.

The section shown in Fig. 11 represents an
excavation made in the middle of the town,
and is here introduced because the bed of " rich
"mould" attained, according to Mr. Joyce, the
unusual thickness of 20 inches. Gravel lay
at the depth of 48 inches from the surface
but it was not ascertained whether this was
in its natural state, or had been brought here
and had been rammed down, as occurs in
some other places.

Chap. IV. OF ANCIENT BUILDINGS.

207

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

Mould, 20 inches
thick.

Rubble wi'h broken
t.les, 4 inches thick.

Black decayed wood,
in th.ckfi~t pait 6
inches thick.

Fig. 11.

Section in a block of buildings in the middle of the town of
Silchester.

reached. The bed marked "" concrete " was
probably at one time a floor ; and the beds
beneath seem to be the remnants of more
ancient buildings. The vegetable mould was

208

BURIAL OF THE REMAINS Chap. IV.

here only 9 inches thick. In some other
sections, not copied, we likewise have

im^ ^'^

- — 1 Mould, 9 inches thick.

%:^

Ligh'-coloured earth with
large pitces of broken
tiles, 7 inches.

Dai k, fine grained rubbish
with small bits oi tiles
20 inches.

Concrete, 4 inches.
Stucco, 2 inches.

Made bottom with frag-
ments of tiles, 8 ibches.

Fine-grained made ground,
with the debrii of older
buildings.

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

evidence of buildings having been erected
over the ruins of older ones. In one case

Chap. IV. OF ANCIENT BUILDINGS. 200

there was a layer of yellow clay of very
unequal thickness between two beds of debris,
the lower one of which rested on a floor with
tesserse. The old broken walls appear some-
times to have been roughly cut down to a
uniform level, so as to serve as the founda-
tions of a temporary building ; and iMr. 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
were observed on the floors of several of the
rooms, in one of which the tesselation was
unusually perfect. The tesserye here con-
sisted of little cubes of hard sandstone of
about 1 inch, several of which were loose
or projected slightly above the general level
One or occasionally two open worm-burrows
were found beneath all the loose tesserye.
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
lar^e flints, and was 18 inches in thickness.

210 BURIAL OF THE REMAINS Chap. IV

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 49 J 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 of the wall ; but as some of the flints
cohered firmly, the whole mass was disturbed
in pulling 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 con-
siderably 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,

Chap. IV. OF ANCIENT BUILDINGS. 213.

and here there were worm-burrows. 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 instea 1
of mortar ; but we sliould remember that
worms line their burrows with black humus.
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
witb their castings, as soon as they were able
to penetrate the wall. Rain-water, oozing
down the burrows 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 was
'' quite impossible such a wall could have been
'* penetrated by earth-worms."

In almost all the rooms the pavement has

212

BUKIAL OF THE EEMAINS Chap. IV.

ui

CO 'T^

^. >
to ^

fe

sunk considerably, especi-
ally towards the middle ;
and this is shown in the
three following sections.
The measurements were
made by stretching a string
tightly and horizontally
over the floor. The sec-
tion, Fig. 13, was taken
from north to south across
a room, 18 feet 4 incVies in
length, with a nearly per-
fect 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 subsided. In
several places, the tessera3
appeared as if drawn a little
away from the walls ; whilst

Chap. IV. OF ANCIENT BUILDINGS. 213

in other places tliey were still in close contact
with them.

In Fig. 14^ we see a section across tlie
paved floor of the southern corridor or
ambulatory 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 3° 40'. The nature 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 dark vegetable mould
which was thicker on the lower or southern
than on the northern side. The pavemeni
was nearly level along lines parallel to the
side-walls, but had sunk in the middle as
much as 7f inches.

A small room at no great distance from that
represented in Fig. 13, had been enlarged by
the Roman occupier on the southern side, by
an addition of 5 feet 4 inches in breadth. For
this purpose the southern wall of the house had
been pulled down, but the foundations of the
old wall had been left buried at a little depth

214

BURIAL OF THE REMAINS Chap, IY

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d

Chap. IV. OF ANCIENT BUILDINGS. 215

beneath the pavement of the enlarged room.
Mr. Jojce beheves that this buried wall must
have been built before the reign of Claudius IT.,
who died 270, a.d. We see in the accom
panying section, Fig. 15, that the tesselated
pavement has subsided to a less degree over the
buried wall than elsewhere ; so that a slight
convexity or protuberance here stretched in a
straight line across the room. This led to
a hole being dug, and the buried wall was
thus discovered.

We see in these three sections, and in
several others not given, that the old pave-
ments 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 enlargement of the
room, which must have been built on fresh
ground, has sunk a little more than on the
old northern side. But this sinking may
possibly have had no connection with the
enlargement of the room, for in Fig. 13,
one half of the pavement has subsided more

15

216

BURIAL OF THE REMAINS Chap. IV.

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_, ^1

^2

■73

o d

> O)

03 a

p.^

J-*^ '^

O =«

C rd

gn

^

•T3 O

q; ••-I

n:j ^

•^, ^

r^ ^

g o
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m

|t^

t3

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rO

o

Oi

Chap. IV. OF ANCIENT BUILDINGS. 217

than the other half without any assignable
cause. In a bricked passage to Mr. Joyce's
own house, laid dowm only about six year8
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
Eoraan builders excavated the ground to an
unusual 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 tesselated and often
ornamented pavements were laid. The sink-
ing must, as it appears to me, be attributed
in chief part to the pavement having been
undermined by worms, which w^e know are
still at work. Even Mr. Joyce at last ad-
mitted 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 w'hich would otherwise be inexplicable. My
sons noticed that in one room in which the
pavement had sagged very little, there was an
unusually small amount of overlying mould.

218 BURIAL OF THE REMAINS Chap. IV

As tlie foundations of the walls generally
He at a considerable depth, they will either
have not subsided at all through the under-
mining action of worms, or they will have
subsided much less than the floor. This
latter result would follow from worms not
often working deep down beneath the founda-
tions ; but more especially from the walls not
yielding 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 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 adhering 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 Silehester 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

Chap. IV. OF ANCIENT BUILDINGS. 219

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
before 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, accord-
ing to Mr. Joyce, are nearly level, and it
appears that the mould is here generally
thicker than elsewhere. The surface slopes
in other pai'ts from west to east, and Mr. Joyce
describes one floor as covered at the western
end by rubbish and mould to a thickness
of 28^ inches, and at the eastern end by a
thickness of only 11^ 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 ]
believe, be explained. Moreover most of the
J and here has long been ploughed, and this
would greatly aid the washing away of the
finer earth during rainy weather.

220 BURIAL OF THE REMAINS Chap. I^*.

The nature of tbe beds immediately
beneath the vegetable mould in some of the
sections is rather perplexing. We see, for
instance, in the section of an excavation in a
grass meadow (Fig. 14), which sloped from
north to south at an angle of 3° 40', that the
mould on the upper side is only six inches
and on the lower side nine inches in thick-
ness. But this mould lies on a mass (2 5 J
inches in thickness on the upper side) " of
'' dark brown mould," as described by Mr.
Joyce, " thickly interspersed with small
" pebbles and bits of tiles, which present a
" corroded or worn appearance." The state
of this dark-coloured earth is like that of a
field which has long been ploughed, for the
earth thus becomes intermingled 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 above
section is rendered intelligible. For worms
will continually have brought up fine earth
from below, which will have been stirred

Ceap. 1Y. of ancient BUILDINGS. 221

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.

JVroxeter, Shropshire. — The old Roman city
of Uriconium was founded in the early 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 undulates slightly, and has long been
under cultivation. It had been noticed that
the corn-crops ripened prematurely in certain
narrow lines, and that the snow remained un-
melted in certain places longer than in others

222 BURIAL OF THE REMAINS Chap. IV.

These appearances led, as I was informed, to
extensive excavations being undertaken. The
foundations of many large buildings and
several streets have thus been exposed to view.
The space enclosed within the old walls is
an irregular oval, about 1| mile in length.
Many of the stones or bricks used in the
buildings must have been carried away ; but
the hyjDocausts, baths, and other underground
buildings were found tolerably perfect, being
filled with stones, broken tiles, rubbish and
soil. 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 applied to Dr. H. Johnson, who
had superintended tlie excavations ; and he,
with the greatest kindness, twice visited the
place to examine it in reference to ray ques-
tions, and had many trenches dug in four
fields which had hitherto been undisturbed.
The results of his observations are given in
the following Table. He also sent me speci-
mens of the mould, and answered, as far ay
he could, all my questions.

Chap. IV. OF ANCIENT BUILDINGS. 223

Measurements by Dr. H. Johnson of the thickness of
the vegetable mould over the roman ruins at
Wroxeteu.

Trenches dug in a field called " Old Works."

Thlcknf^ss

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
o. „ „ 9 inches concrete was reached 9

Trenches dug in a field called '^Shop
"Leasows ;" this is the highest field within the
old walls, and slopes down from a sub-central
[^oint 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 89
inches deep ; the mould here graduated into
tho 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
iO 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

221 BUKIAL OF THE REMAINS Chap. IV

Thickneg«i

of mould in

Inches.

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

deep, stopped by concrete .. .. ., 9 2

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.

Thickness

of mould in

inches.

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

18. „ 10 inches deep, and then came U]ion a
causeway .. .. .. .. ..10

19. Trench 34 inches deep .. .. , .. 30

20. „ 31 inches deep ' .. 31

Field on the western side of the space
enclosed within the old walls.

Thickness

of mould in

inches

21. Trench 28 inches deep, when undisturbed sand

w^as reached .. .. .. .. .. 16

22. Trench 29 inches deep, when undisturbed sand

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

23. Trench 14 inches dee}>, and then came upon j*

building ., .. .. ., ..14

Dr. Johnson distinguished as mould the
earth which differed, more or less abruptly, in

Chap. IV. OF ANCIENT BUILDINGS. 225

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
pasture-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-
cultivated. Bearing in mind the remarks
made in 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 ob-
served, 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 sum-
mit 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

226 BURIAL OF THE REMAINS Chap. IV

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 beneatV
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 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 it
they had subsided from having been under-
mined. The foundations of some of the walls,
for instance those of the portion still stand-
ing about 20 feet above the ground, and
those of the market-place, lie at the extra-
ordinary depth of 14 feet; but it is highly
improbable that the foundations were o^ener-

Chap. IV. OP ANCIENT BUILDINGS. 227

ally SO deep. The mortar employed in the
buildings must have been excellent, for it
is still in parts extremely hard. Where-
ever walls of any height have been exposed
to view, they are, as Dr. Johnson believes,
still perpendicular. The walls with such
deep foundations cannot have been under-
mined 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 being now com-
pletely covered with earth; but how much
of this covering consists of vegetable mould
and how much of rubble I do not know.
The market-place, with the foundations 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
covered with earth, w^e must suppose, either
that the upper layers of stone have been at

228 BUKIAL OF THE EEMAINS Chap. IV.

some time carried away by man, or that earth
has since been washed down during heavy
rain, or blown down during storms, from the
adjoining laud ; and this would be especially
apt to occur where the land has long been
cultivated. In the above cases the adjoining
land is some^vhat higher than the three speci-
fied sites, as far as I can judge by maps and
from information given me by Dr. Johnson.
If, however, a great pile of broken stones
mortar, plaster, timber and ashes fell over the
remains of any building, their disintegration
in the course of time, and the sifting action
of wormSj would ultimately conceal the whole
beneath fine earth.

Conclusion. — The cases given in this chapter
show that worms have played a considerable
part in the burial and concealment of several
Roman and other old buildings in England ;
but no doubt the washing down of soil from
the neighbouring higher lands, and the de-
position of dust, have together aided largely
in the work of concealment. Dust would be
apt to accumulate wherever old broken-down
walls projected a little above the then exist-

Chap. IV. OF ANCIENT BUILDINGS. 229

ing surface and thus afforded some shelter.
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
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
inclination from the perpendicular.

liJO DISINTEGRATION Chap. V.

CHAPTER Y.

THE ACTION OF WORMS IN^ THE DExVUDATION
OF THE LAND.

Evidence of the amount of denudation which the land has
undergone — Subaerial denudation — The depo^ition 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 ot
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 outbursts,
that we owe our sedimentary formations.
These after being consolidated and sometimes

Chap. Y. AND DENUDATION. 231

recrystalllzed, have often been again dis-
integrated. Denudation means the removal
of such disinteo^rated matter to a lower level.
Of the many striking results due to the
modern 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 denudation ; but until the successive forma-
tions were carefully mapped and measured,
no one fully realised how great was the
amount. One of the first and most remark-
able memoirs ever published on this subject
was that by Ramsay,* who in 1846 showed
that in Wales from 9000 to 11,000 feet in
thickness o'' solid rock had been stripped of!
large tracks of country. Perhaps the plainest
evidence of great denudation is afforded by
faults or. cracks, which extend 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

* " On the denudation of South Wales," &c., ' Memoirs of tha
Geological Survey of Great Britain,' vol. i., p. 297, 1846.
1(}

2o2 DISINTEGEATION Cuap. V

land. A huge pile of 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
undoubtedly ancient coast-lines ; but we now
know that they stand u|) 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 memoir; but Mr. Whitaker, of the
Geological Survey of England, was so for-
tunate when, in 1867, he published his paper
'' On sub-aerial Denudation, and on Cliffs and
Escarpments of the Chalk." * Before thi.s

* ' Geological Magazine,' October and November, 1867, vol.
Iv. pp. 447 and 483. Copious references on the subject are giv,.a
in tiiis remarkal)le memoir.

Chap. V. AND DENUDATION. 233

paper appeared, Mr. A. Tylor had adduced
important evidence on sub-aerial denudation,
by showing that the amount of matter
brought down by rivers must infaUibly low^er
the level of their drainage-basins by many
feet in no immense lapse of time. This line
of argument has since been foUov^^ed 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 single
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

* A. Tylor " On changes of the sea-level," &c., ' Philosophical
Mag.' (Ser. 4th) vol. v., 1853, p. 258. Archibald Geikie,
Transactions Greolog. Soc. of Glasgow, vol. iii., p. 153 (read March,
1868). Croll "On Geologicaf Time," 'Philosophical Mag.',
May, August, and November, 18G8. See also Croll, ' Climate
and Time,' 1875, Chap. XX. For some recent information on
ihe amount of sediment brought down by rivers, see * Nature,'
Sept. 23rd, 1880. Mr. T. Mellard Peade has published some
interesting articles on the astonishing amount of matter
brought down in solution by rivers. See Address, Gcolog. Soc.,
Liverpool, 187G-77.

234 DISINTEGRATION Chap. V

drainage must be lowered ^sVe ^^ ^ ^^'^^
annaally, or 1 foot in 4566 years. Con-
sequently, taking the best estimate of the
mean height of the North American continent,
viz. 748 feet, and looking to the future, the
whole of the great 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 re-
latively to their size, and some much less than
the Mississippi.

Disintegrated matter is carried away by
the wind as well as by running water
During volcanic outbursts much rock is
triturated and is thus widely dispersed ; and
in all arid countries the wind plays an im-
portant 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

* '* An account of the fine dust which often fcills on Vessels in
the Atlantic Ocean," Proc. Gee log. Soc. of London, Jime 4ih,

lb45.

Chap. V. AND DENUDATION. 235

space of 1600 miles in latitude, and for a
distance of from 300 to 600 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 ex-
tremely fine dust coming from Africa was con-
tinually 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 y^Q-o of an
inch square. Nearer to the coast the water
has been seen to be so much discoloured by
the falling dust, that a sailing vessel left a
track behind her. In countries, like the Cape
Yerde Archipelago, where it seldom rains
and there are no frosts, the solid rock never-
theless disintegrates ; and in conformity with
the views lately advanced by a distinguished
Belgian geologist, De Koninck, such disin-
tegration 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,

23G DISINTEGEATION Chap. V.

countries, worms aid in the work of denuda-
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 ap-
pearance 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 alimentary canal of a worm.
This sifting of the soil is aided, as has already
been remarked, by burrowing animals of
many kinds, especially by ants. In countries
wdiere the summer is long and dry, the
mould in protected places uiust 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 law-
suits arose. Immense quantities of dust are
likewise blov/n about in Egypt and in the

Chap. Y. AND DENUDATION. 237

south of France. In China, as Richthofen
maintains, beds appearing like fine sediment,
several hundred feet in thickness and extend-
ing 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 con-
dition^ the fields near high roads, where there
is much traffic, must receive a considerable
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 trans-
ported from one place to another. The dust
which falls so thickly within our houses con-

* For La Plata, see my * Journal of Eesearches,' during the
TDyage of the Beagle, 1845, p. 133. !^lie de Beaumont has
given (' Le9ons de Geolog. pratique,' torn. I, 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.

238 DISINTEGRATION Chap. Y

sists largely of organic matter, and if spread
over the land would in time decay and dis-
appear almost entirely. It appears, however,
from recent observations on the snow-fields
of the Arctic rea-ions, that some Httle meteoric
dust of extra mundane origin is continually
falling.

The dark colour of ordinary mould is
obviously due to the presence of decaying
organic 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 com-
bination being dispelled. In one sample of
fertile mould the amount of organic matter
was ascertained 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 ol
Eussia 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

* These statements are taken from Von Hensen in * Zeitsclirift
fiir 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. 314.

Chap. Y. AND DENUDATION. 239

64 per cent. ; but with tliese latter cases we
are not here concerned. The carbon in the
soil tends gradually to oxidise and to dis-
appear, except where water accumulates and
the climate is cool ; * so that in tlie oldest
pasture-land there is no great excess of
organic matter, notwithstanding the con-
tinued decay of the roots and the underground
stems of plants, and the occasional addition
of manure. The disappearance of the organic
matter from mould is probably 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 to a depth of 2
or 3 inches. They do this chiefly for obtain-
ing 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

* 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.

240 DISINTEGKATION Chap. Y.

earth ; and it is this process ^hich gives to
vegetable mould its uniform dark tint. It is
known that various kinds of acids are gen-
erated by the decay of vegetable matter ; and
fiom the contents of the intestines of worms and
from their castings being acid, it seems pro-
bable that the process of digestion induces an
analogous chemical change in the swallowed,
triturated, and half decayed leaves. The large
quantity of carbonate of lime secreted by the
calciferous glands apparently serves to neutra-
lise 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 in-
testines 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 w^orms are formed during the diges-
tive process ; and that probably they are
nearly of the same nature as those in ordinary
humus. The latter are Avell known to have
the power of de-oxidising or dissolving per-
oxide of iron, as may be seen wherever peat
overlies red sand, or where a rotten root
penetrates such sand. Now I kept some
woims in a pot filled with very fine reddish

Chap. V. AND DEN UDATION. . 241

sand, consisting of minute particles of silex
coated with the red 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 intestinal 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 oxide; 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 Pharmacopoeia^ 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
different kinds. These acids, as well as their
acid salts (i.e., in combination with potash,
Boda, and ammonia), act energetically on

212 DISINTEGRATION Chap. V,

carbonate of lime and on the oxides of iron.
It is, also, known that some of these acids,
which were called lons^ ago by Thenard azo-
humic, are enabled 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
excess of carbonic acid in all soils, especially
in rich soils, and this is dissolved by the water

* A. A. Julieu " On the Geological action of the Humus-acids,"
' Proc. American Assoc. Science,' vol. xxviii., 1879, p. 311.
Aho on " Chemical erosion on Mountain Summits ;" ' New York
Academy of Sciences,' Oct. 14, 1878, as quoted in the 'American
Katuralist.' See also, on this subject, S. W. Johnson, '* How
Crops Feed," 1870, p. 138

Chap. V. AND DENUDATION, 243

in the ground. The living roots of plantS;
moreover, as Saclis and others have shown,
quickly corrode and leave their impressions
on polished slabs of marble, dolomite and
phosphate of lime. They will attack even
basalt and sandstone.* But we are not hero
concerned with agencies which are wholly
independent of the action of worms.

The combination of any acid with a base
is much facilitated by agitation, as fresh
surfaces are thus continually brought into
contact. This will be thoroughly effected
with the particles of stone and earth in the
intestines of worms, during the digestive pi'o-
cess ; and it should be remembered that tho
entire mass of the mould over every field,
passes, in the course of a few years, through
their alimentary canals. Moreover as the old
burrows slowly collapse, and as fresh castings
are continually brought to the surface, the
whole superficial layer of mould slowly re-
volves or circulates ; and the friction of the
particles one with another will rub off the
finest films of disintegrated matter as soon aa

* See, for references on this subject, S. W. Johnson, " How
Crops Feed," 1870, p. 326.

244 DISINTEGRATION Chap. V.

they are formed. Througli these several
means, minute fragments of rocks of many
kinds and mere particles in the soil will be
continually exposed to chemical decomposi-
tion ; 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 thickness of the soil, if none be re-
moved from the surface, w^ill steadily though
slowly tend to increase ; 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 com-
pounds, and are liable to decomposition before
they reach any considerable depth.* A thick
bed of overlying soil will also check the
downward extension of great fluctuations of
temperature, and in cold countries will check

• This statement is taken from Mr, Julien, ' Pioc. American
Assoc. Science ' vol. xxviii., 1879, p. 330.

Chap. Y. AND DENUDATION. 2 15

tlie powerful action of frost. TLe free access
of air will likewise be excluded. From those
several causes disintegration would be almost
arrested, if the overlying mould were to
increase much in thickness, owing to none or
little being removed from the surface.* In
my own immediate neighbourhood we have a
curious proof how effectually a few feet of
clay checks some change which goes on in
flints, lying freely exposed ; 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

* The preservative power of a layer of mould and turf is often
stcwTi 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
\vhich 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 re-
moval by atmospheric agencies of the outer modified surfaces
of freely exposed flints, though no doubt excessively slow, to-
gether with the modification travelling inwards, will, as may Vq
suspected, ultimately lead to their complete disintegration, not-
withstanding that they appear to be so extremely durable.

246 DISINTEGRATION Chap. V.

therefore necessary to obtain flints for build-
ing purposes from the bed of red clay over-
lying 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
swallow earth are furnished with gizzards ;
and these are lined with so thick a chitinous
membrane, that Perrier speaks of it,* as ^' une
veritable armature." The gizzard is sur-
rounded by powerful transverse muscles,
which, according to Claparede, are about ten
times as thick as the longitudinal ones ; and
Perrier saw them contracting energetically.
Worms belonging to one genus, Digaster,
have two distinct but quite similar gizzards ;
and in another genus, Moniligaster, the
second gizzard consists of four pouches, one
succeeding the other, so that it may almost
be said to have five gizzards.f In the same

• ' Archives de Zoolog. exper.' torn. iii. 1874, p. 409.
t ' Nouvelles Archives du Museum,' torn. viii. 1872, p. 95|
131.

Chap. V. AND DENUDATION. 247

manner as gallinaceous and strufchious birds
swallow stones to aid in the trituration of
their food, so it appears to be with terricolous
worms. The gizzards 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 cal-
ciferous 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, a?
the gizzards were opened late in the autumn
when the worms had ceased to feed and theii
gizzards were quite empty.*

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 are found in their gizzards. For
beads of glass and fragments of brick and of
hard tiles were scattered over the surface

* Morren, in speaking of the earth in the alimentary canals oi
worms, says, " praesepfe cum lapillis commixtam vidi ; " * De
Lumbrici terrestris,' &c., 1829, p. 16.

ir

248 DISINTEGRATION Cuap. V.

of the earth, in pots in which worms were
kept and had already made their burrows ;
and very many of these beads and fragments
were picked np and swallowed by the worms,
for they were found in their castings, intes-
tines, and gizzards. They even swallowed
the coarse red dust, formed by the pounding
of the tiles. Nor can it be supposed thai
they mistook the beads and fragments for
food ; for we have seen that their taste is
delicate enough to distinguish between dif-
ferent kinds of leaves. It is therefore
manifest that they swallow hard objects,
such as bits of stone, beads of glass and
angular 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 consume. That such hard
objects are not necessary 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 not provided with gizzards,* and

• Perrier, ' Archives de Zoolog. exper.' torn. iii. 1874, p. 419,

CiiAr. V. AND DENUDATION. 249

therefore cannot have the poAver of utilising
stones.

During the grinding process, the particles
of earth must he ruhbed against one another,
and between the stones and the tough
lining membrane of the gizzard. The softer
particles will thus suffer some attrition, and
will perhaps even be crushed. This con-
clusion is supported by the appearance of
freshly ejected castings, for these often re-
minded 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." * Perrier also
speaks of " I'etat de pate excessivement fine a
laquelle est reduite la terre qu'ils rejettent,"
&c.t

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
evidence on this head by carefully examining
many of the fragments which had passed

* Morren, * De Lumbrici terrestris,' &c., p. 1 6.

X ' Archives de Zoolog. Expdr.' torn. iii. 1874, p. 418.

250 DISINTEGKATION CnAr. V.

through their alimentary canals. With
worms living in a state of nature, it is of
CDurse impossible to know how much the
fragments may have been worn before they
were swallowed. It is, however, clear that
worms do not habitually 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
become 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 re-
peatedly through their gizzards, visible signs
of attrition in the fragments could hardly be
expected, except perhaps in the case of very
soft stones.

Chap. V. AND DENUDATION. 25 1

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 concre-
tions formed in the calciferous glands, which
are often found in their gizzards, intestines,
and occasionally in their castings, when of
large size, sometimes appeared to have been
rounded; but with all calcareous bodies
the rounded appearance may be partly or
wholly due to their corrosion by carbonic
acid and the humus-acids. In the gizzards
of several worms collected in my kitchen
garden near a hothouse, eight little frag-
ments of cinders were found, and of these,
six appeared more or less rounded, as were
twc bits of brick; but 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

252 DISINTEGRx\TION Chap. V.

rubbish on both sides 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 contained very many
particles of brick, all more or less rounded ;
and this brick-rubbish, after being shot into
the hole, could not have undergone any
attrition. Again, old bricks very little
broken, together with fragments of mortar,
w^ere 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.

CiiAP. Y. AND DENUDATION. 253

There were also very many particles of hard
mortar, about half of which were w^ell
rounded; and it is not credible 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
afforded 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 swallowed and brought to
the surface many times in the course of cen-
turies. It should be premised that in tlie
several following cases, the finer matter was
first washed away from the castings, and
then all the particles of bricks, tiles and con-
crete were collected without any selection, and
were afterwards examined. Now in the cast-
ings ejected between the tesseras on one of the
buried floors of the Roman villa at Abinger,
there were many particles (from | to 2 ram.
in diameter) of tiles and concrete, which it

254 DISINTEGKATION Chap. Y.

was impossible to look at with the naked eye
or through a strong lens, and doubt for a
moment that they had almost all undergone
much attrition. I speak thus after having
examined small water-worn pebbles, formed
from Roman bricks, which M. Henri do
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
gizzards of worms, but the larger ones were
somewhat smoother.

Four castings found on the recently un-
covered, tesselated 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
mortar, however, seemed to have suffered
more corrosion than attrition, for grains of
si lex often projected from their surfaces.
Castings from within the nave of Beaulieu

Chap. V. AND DENUDATION. 255

Abbey, which was destroyed by Henry YIIl.,
were collected from a level expanse of turf,
overlying the buried tesselated pavement,
tlirough which worm-burrows passed ; and
these castings contained innumerable particles
of tiles and bricks, of concrete and cement,
the majority of which had manifestly under-
gone some or much attrition. 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 inherent probability, we
must then assume that in all the above cases
the many rounded fragments found in the
castings had all accidentally undergone much
attrition before they were swallowed ; and
this is highly improbable.

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 ex-
ception of one or two of the smallest grains,
not at all rounded. Nevertheless some of

2dQ disintegration Chap. V.

them appeared 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 millstones 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
castings largely consist, is in part due to the
mechanical 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 during
each heavy shower of rain. If the softer stones
yield at all, the harder ones will suffer
some slight amount of wear and tear.

* This conclusion reminds me of the vast amount of extremely
fino 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-Eeefs,' 2nd edit. 1874, p. 19), be attributed
to the innumerable annelids and other animals which burrow
into the dead coral, and to the fishes, Holothurians, &c., which
browse on th(! living corals.

Chap. Y. AND DENUDATION. 257

The trituration of small particles of stone
in the gizzards of worms is of more import-
ance 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 disintegration, namely running
water and the weaves of the sea, act with
less and less power on fragments of rock the
smaller they are. " Hence," as he remarks,
*' even making no allowance foi" the extra
" buoying up of very minute particles by a
" current of water, depending 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 ^^ of an inch in
" diameter, and at least a hundred times as
*' much as one xoVo ^^ ^^ ^^^^ ^'^ diameter.
" Perhaps, then, we may conclude that a
" grain -f^ of an inch in diameter would be
'^ worn as much or more in drifting a mile as
*' a grain y^Vo ^^' ^'^ ^^^^^^ ^'^ being drifted
** 1 00 miles. On the same principle a pebble
*' one inch in diameter would be worn re-
" latively more hj being drifted only a few

258 DISINTEGRATION, ETC. Chap. V.

** hundred yards."* Nor should we forget, 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 inhahit, a weight of
more than ten tons of earth annually 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 ot
acres fully stocked with worms ; and in
England, together with Scotland, the land
which is cultivated and is v/ell 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. 50.

CHAPTER YI.

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 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.

We are now prepared to consider the more
direct part which worms take in the denuda-
tion of the land. When reflecting on sub-
aerial 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

260 DE>sUDATION OF THE LAND Chap. YI

water- spouts would remove all tlie mould
from a very gentle slope ; but when ex-
amining 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 Avas plain from the
well-preserved state of the three successive
^' roads " or lake-margins. But the difficulty
in believing that earth in any appreciable
quantity can be removed from a gently in-
clined surface, 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 levi-
gated 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 tv'^
occur when they are started by the wind,
and probably wdien started by the touch of an
animal, liowever small. "We shall also see
that a strong wind blows all the castings,

Chap. YI. AIDED BY WOEMS. 261

even on a level field, to leeward, 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
Le, 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 hj

262 DENUDATION OF THE LAND Chap. VL

me after heavy rain, in many places on land
of all kinds.

On the flowing of wet castings, and the
rolling of dry disintegrated eastings down
inclined surfaces,-— Wh^xi castings are ejected
on an inclined 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 castings were con-
siderably elongated in the line of the slope ;
and that they now consisted of smooth^ only
shghtly conical masses. Whenever the
mouths of the burrows could be found from
which the earth had been ejected, there was
more earth below than above them. After
come 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

Chap. VI. AIDED BY WORMS. 263

of the castings thrown up on the level parts
of these same fields. On some fine grassy
slopes in Holwood Park, inclined at angles
oetween 8"^ and 1 1"^ 30' with the horizon,
where the surface apparently had never been
disturbed by the hand of man, castings
abounded in extraordinary numbers ; and a
space 16 inches in length transversely 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 confluent 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 7^ 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 distinguished. 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
fowing-down of these yellow castings after
heavy rain, could be clearly seen where the
slope was 5° ; and where it was less than 1*^
gome evidence of their flowing down could

18

264 DENUDATION OF THE LAND Chap. YL

still be detected. On another occasion, after
rain which was never heavy, but which lasted
for 18 hours, all the castings on this samo
gentl};^ inclined lawn had lost their vermiform
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 surface at
the eleven places where these castings were
collected varied between 4"^ 30' and 17° 30';
the mean of the eleven inclinations being
9° 26'. The length of tlie castings in the
direction 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 ^ 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

Chap. YL AIDED BY WOEMS. 265

of tlie bnrrow, wliicli was discovered by slicing
oiF the turf; and all the ejected earth was
separately 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 np almost 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 important in determining
the quantity of the earth which flows down a
slope than its angle. Thus with four castings
on my lawn (included in the above eleven)
where the mean slope was 7° 19', the difference
in the amount of earth above and below the
burrows was greater than with three other

266 DENUDATION OF THE LAND Chap. VL

castings on the same lawn where the mean
slope was 12° 5'.

We may, however, take the above eleven
eases, 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 9° 26'. This was done
hy 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-thiid above and the upper
half of the two-thirds below, there is no flow
of earth down the hill-side. The earth con-
stituting 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 -casting. Now the

Chap. VI. AIDED BY WOEMS. 267

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 displacement of the earth to
be through one inch. But it appears that
only -J of the earth brought up can be con-
sidered to flow downwards ; hence -g- of -g^ or
-j-^8 of 7*453 lbs. will cross the lower side of
our square yard in a year. Now -^ww ^^
7*453 lbs. is 1*1 oz. Therefore 1"I oz. of dry
earth will annually cross each linear yard run-
ning horizontally along a slope having the
above inclination ; or very nearly 7 lbs. will

268 DENUDATION OF THE LAND Chap. VL

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

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 therefo] e follows by a
calculation similar to the one already given,
that -J- of '2 X 36^ or 2*4 cubic inches of damp
earth will annually cross a horizontal 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. Therefore
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 Isngth 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

CuAP. VI. AIDED BY WORMS. 269

before 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 ex-
tremely 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 quantity of fine earth.
Dried castings, moreover, are apt to disinte-
grate into little pellets, which often roll or
are blown down any inclined surface. There-
fore 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 branching 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

270 DENUDATION OF THE LAND Chap. YI.

earth, weighing 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 shortest course for bringing up earth
from beneath, then as the old burrows col-
lapsed from the weight of the superincum-
bent soil, the collapsing would inevitably
cause the whole bed of vegetable mould to
sink or slide slowly down the inclined sur-
face. But to ascertain the direction of many
burrows was found too difficult and trouble-
some. A straight piece of wire was, how-
ever, 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,

Chap. VI. AIDED BY WORMS. 271

as in the tropics, the castings appear, ag
might have heen expected, to be washed
down in a greater degree than in England.
Mr. Scott informs me that near Calcutta the
tall columnar castings (previously described),
the diameter of which is usually between i
and IJ 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 elongated
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 diameter
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

272 DENUDATION OF THE LAND Chap. VL

its castings, not in vermiform masses, but in
little pellets 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 precipi-
tated chalk, moistened with saliva or gum-
water, so as to be slightly viscid and of the
same consistence 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 ihus
treated subsided with surprising slowness,
owing as I suppose to its viscidity. It did
not fiow bodily down the grass-covered sur-
face of the lawn, which was here inclined at
an angle of 16° 20',* nevertheless many par-

Chap. VI. AIDED BY WORMS. 273

tides of the chalk were found three inches
below the casting. The experiment was re-
peated on three other castings on different
parts of the lawn, which sloped at 2° 30',
3° and 6°; and particles of chalk could be
seen between 4 and 5 inches below the cast-
ing ; 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 precipitated 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 some-
what white for a distance of one inch from
the casting ; and some soil collected at a dis-
tance of 2~ inches, where the slope was 7°_,
effervesced slightly when j)laced 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

274 DENUDATION OF THE LAND Chap. YI.

very porous, and the water in them is often
slightly muddy ; when such little pools have
dried, the leaves and hlades 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 110 days. He carefully
examined 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 disintegration of the castings if
they had not been wholly removed. He
Ihei'ofore has no hesitation in asserting that
the whole of these huge castings are annually
washed during the two monsoons (when

CiiAP. VI. AIDED BY WORMS. 275

about 100 inches of rain fall) 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 secre-
tions. Frost seems to be less effective in
their disintegration than might have been
expected. Nevertheless they readily disin-
tegrate into small pellets, after being alter-
nately 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 castings, was completely
covered with these pellets or disintegrated
castings, which had rolled down the steep
sides, inclined at an angle of 27°.

Near Nice, in places where the great cylin-
drical castings, previously described, abound,
the soil consists of very fine arenaceo-cal-
careous loam ; and Dr. King informs me that

276 DENUDATION OF THE LAND Chap. YI.

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 distinguisli*
able 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 down 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 |- of an
inch in diameter to minute grains and mere
dust. Dr. King witnessed the crumbling
process whilst drying some perfect castings,
which he afterwards 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 disinteg-
rated fragments rolled downwards, without
losing their distinctive shape ; and in som«
places could " be collected in basketfuls." Dr.
King observed a striking instance of this fact
on the Corniche road, where a drain, about
2^ feet wide and 9 inches deep, had been made

Chap. Y1. AIDED BY WOEMS. 277

to catch tlie surface drainage from the adjoin-
ing hill-side. The bottom of this drain was
covered for a distance of several hundred
yarc's, to a depth of from 1^ to 3 inches, by a
layer of broken castings, still retaining their
characteristic shape. Nearly all these in-
numerable fragments had rolled down from
above, for extremely 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 60° with
the horizon. He climbed up the slope, and
" found every here and there little embank-
" ments, formed by fragments 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
" retained the form of castings." Dr. King
dug up this plant, and was struck with
the thickness of the soil which must have
recently accumulated over the crown of the
rhizoma, as shown by the length of the

278 DENUDATION TO LAND Chap. \L

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 everywhere seen) by the
smaller roots of the plants. After describing
this and other analogous cases, Dr. King con-
cludes : " 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. Hooker
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
animals and not many wild ones ; but these
latter would, it is probable, use the ledges at
flight while grazing like our domesticated
nnimals, A friend observed for me the ledges

Chap. YL LEDGES ON HILL-SIDES. 279

on the Alps of Switzerland, and states thai
they ran at 3 or 4 ft. one above the other
and were about a foot in breadth. They had
been deeply 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
horizon, about 30 flat ledges extended hori-
zontally 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
parallelism ; 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
Ihe 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

19

280 DENUDATION TO LAND Chap. VL

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 oank bearing
these ledges, the surface consisted in parts of
bare chalk, and here the ledges were very
irregular. At the other end of the bank, the
slope suddenly became less steep, and here the
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

Chap. YI. LEDGES ON HILL-SIDES. 281

the inland side of Beachy Head, where the
surface sloped at about 25°, 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 measurements, 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 em-
bankments showed no signs of having been
trampled on by sheep, but in the lower parts
such signs were fairly plain. No long con-
tinuous 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 dis-
integrated and rolled worm-castings, were to
become confluent along horizontal lines, ledges
would be formed. Each embankment would
tend to extend laterally by the lateral extension
of the arrested castings; and animals grazing on
a steep slope would almost certainly make use

282 DENUDATION TO LAND Chap. Yl

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 distintegrated matter from above,
and would tend to be obliterated by rain and
other atmospheric agencies. There is some
analogy between the formation, as here sup-
posed, of these ledges, and that of the ripples
of wind-drifted sand as described by Lyell.*

The steep, grass-covered sides of a
mountainous valley in Westmoreland, called
G-risedale, was marked in many places with
innumerable, almost horizontal, little ledges,
or rather lines of miniature cliffs. Their
formation was in no way connected with the
action of worms, for castings could not any-
wiiere be seen (and their absence is an
inexplicable fact) although the turf lay in
many places over a considerable thickness of

* ' Elements of Geology,' 18G5, p. 20

Chap. YI. LEDGES ON HILL-SIDES. 283

boulder-clay and moraine rubbish. Nor, as
far as I could judge, was the formation of
these little cliffs at all closely connected with
the trampling of cows or sheep> It appeared
as if the whole superficial, somewhat argil-
laceous 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 leevjard 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
surfaces, are blown during gales of wind ac-
companied by rain to leeward. This has been
observed by me many times on many fields
during several successive years. After such
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-groimd hillocks
of rock. They are often cavernous on the

284- DENUDATION OF THE LAND. Chap. VL

leeward side, from the upper part having
curled over the lower part. During one un-
usually 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. Eecent castings naturally flow down
an inclined surface, but on a grassy field,
which sloped between 10° and 15°, several
were found after a heavy gale blown up the
slope. This likewise 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 instead 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 0° 45', 1°, 3° and
3° 30' (mean 2° 45') towards the north-cast,
after a heavy south-west gale with rain, were
divided across the mouths of the burrows and
weighed in the manner formerly described.
The mean weight of the earth below the
mouths of burrows and to leeward, was to that

Chap. YI. CASTINGS BLOWN TO LEEWAKD. 2S5

above tlie nQOuths 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 inchnation of 9° 26', and with
three castings where the inclination was
above 12°, 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
moderately 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. Thk was observed on four
occasions, but I did not sufficiently attend to
this point. One old casting on a gently slop-
ing bank was blown quite away by a strong
south-west wind. Dr. King believes that
the wind removes the greater part of the
old crumbling castings near Nice. Several
old castings on my lawn were marked with
pins and protected from any disturbance.
They were examined after an interval of 10

286 DENUDATION OF THE LAND. Chap. YI,

weeks, duriog wbicli time the weather had
been alternately dry and rainy. Some, which
were of a yellowish colour had been washed
almost completely away, as could be seen
by the colour of the surrounding ground.
Others had completely disappeared, and these
no doubt had been blown away. Lastly,
others still remained 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 con-
sist 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
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
interesting, 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

Chap. VI. CASTINGS BLOWN TO LEEWAED. 287

will never be removed as long as tlie 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 cast/-
ings, by our wet southern gales to the north-
east, over open and flat land, by looking to
the level of the surface on opposite sides of
old trees and hedge-rows ; but 1 failed owing
to the unequal growth of the roots of trees
and to most pasture-land having been formerly
ploughed.

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

288 DENUDATION OF THE LAND. Chap. VL

six observations made at a distance of 10 yards
outside 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
protracted 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
nortli-west and north-east; and thinnest in
the quarter between south-east and south-
west, especially at this latter point. Besides
the foregoing measurements, six others were
taken 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 measure-
ments on the south-west side was only 1*46
inches. These observations indicate that the
castings had been blown by the south-west
winds from the circular enclosed space into

Chap. VI. CASTINGS BLOWN TO LEEWARD. 289

the trencli 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 Tvould
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,
from which the amount of denudation may
be measured.* He ignores the continued
formation of fresh mould by the disintegra-
tion of the underlying rocks and fragments of
rock ; and it is curious to find how much
more philosophical were the views, main-

* " Lecons de Geologie pratique, 1845 ; cinqiiieme Le9on.
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.

290 DENUDATION OF THE LAND. Chap. VL

tallied long ago, by Playfair, who, in 1802,
wrote, *' in the permanence of a coat of
'' vegetable mould on the surface of the earth,
" we have a demonstrative proof of the con-
" tinned 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 indirect, but apparently trustworthy, evi-
dence that the slopes of the old embankments
are the same as they originally were ; and it
is obvious that he could know nothing about
their original heights. In Knole Park a
mound had been thrown up behind the rifle-
targets, which appeared to have been formed
of earth originally 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 northern side, with long coarse grass,

• 'Illustrations of the Iluttonian Theory of the Earth/ p. 107,

CiiAi'. YI. ANCIENT MOUNDS. 291

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 thia
kind is tenanted 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 favourable for worms ; so that a
greater Dumber 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 lowering of the whole mound,
whilst the inclination 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 unfavourable 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

292 DENUDATION OF THE LAND. Chap. VL

two inches in 10 years. Therefore in so long
a period as 2000 years, a large amount of
earth will have been repeatedly brought to
the surface on most old embankments 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
remote period and in many countries, land
has been ploughed, so that convex beds,
called 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 ascertain how long a time these
crowns and furrows last, when ploughed land
has been converted into pasture, obstacles of
many kinds were encountered. 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 after

Chap. VI. ANCIENTLY PLOUGHED FIELDS. 293

wards 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 seema
to have been ploughed in Britain. There is,
however, no reason to doubt that in many
eases the old crowns and furrows have been
preserved from a very ancient period.* That
they should have been preserved for very
unequal lengths of time would naturally
follow from the crowns, when first thrown
up, having differed much in height in dif-
ferent 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

* Mr. E. Tylor in his Presidential address ('Jouraal of the
Anthropological Institute,' May 1880, p. 451) remarks: "It
appears from several papers of the Berlin Society as to tho
German 'high-fields' or 'heathen-fields* (Eochacker, and
Heidenacker) that they correspond much in their situation on hills
and wastes with the ' elf-furrows ' of Scotland, which popular
mythology accounts for by the story of the fields having been
put under a Papal interdict, so that people took to cultivating
the hills. There seems reason to suppose that, like the tilled
plots in the Swedish forests which tradition ascribes to the Did
' hackers,* the German heathen-fields represent tillage by an
ancient and barbaric population."

294 DENUDATION OF TEE LAND. Chap. VI

on tlie crowns ; but this would naturally
follow from the finer earth having been
washed from the crowns into the furrows
before the land was well clothed with turf;
and it is impossible 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 rain from the crowns into the furrows.
But as soon as a bed of fine earth had by any
means been accumulated 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 sloping land 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 castings down
their gentle inclinations into the furrows.

Nevertheless it might be expected that old
furrows, especially those on a sloping surface,

Chap. VI. ANCIENTLY PLOUGHED FIELDS. 295

would in the course of time be filled up and
disappear. Some careful observers, however,
who examined fields for me in Grloucestershire
and Staffordshire, could not detect any dif-
ference in the state of the furrows in the
upper and lower parts of sloping fields, sup-
posed 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 com-
menced in some places. Thus in a grass
field in North Wales, known to have been
ploughed about 65 years ago, which sloped at
an angle of 15° to the north-east, the depth
of the furrows (only 7 feet apart) was care-
fully 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 another field
sloping at about the same angle to the south-
west, the furrows were scarcely perceptible
in the lower part ; although these same
furrows when followed on to some adjoining
level ground were from 2^ to 3^ inches in
depth. A third and closely similar case was

20

296 DEi^UDATION OF THE LAND. Chap. YI.

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,
sloping at from 8° to 10°, which an old shep-
herd said had not been ploughed within the
memory of man. The depth of one furrow
was measured 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 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 aboA^e the steepest part of the slope ; and
at the base, in the middle of the narrow
valley, at a point which the furrow if con-
tinued would have struck, it amounted to 7
inches. On the opposite side of the valley,
there were very faint, almost obliterated,
traces of furrows. Another analogous but
not so decided a case was observed at a few
miles distance from Stonehenge. On the

Chap. Y1. MOULD OYER TEE CHALK. 297

whole it appears that the crowns and fur-
rows on land formerly ploughed, but now
covered with grass, tend slowly to disappear
when the surface is inclined ; and this is pro-
bably 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
observed 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-
ovei, 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 timo
whether I had not exaggerated the amount
of fine earth which flows or rolls down grass-
covered slopes under the form of castings ; and

298 DENUDATION OF THE LAND. Chap. VI.

I sougbt 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 penetrate 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, con
sists of the undissolved residue from the chalk.
It mav be well here to recall the case of the
fragments 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 musl

Chap. VL MOULD OVER THE CHALK. 299

have been effected by the carbonic acid in
the rain and in the ground, by the humus-
acids, and by the corroding 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 present 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
hardly be doubted. My son collected some
powdered and fragmentary chalk beneath the
turf near Winchester ; the former was found
by Colonel Parsons, 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 re-
sidue 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 con-

300 DENUDATION OF THE LAND. Chap. VI

tained 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 liiight
here be less pure than elsewhere. The cause
of the residue accumulating more in some
places than in others, may be attributed 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
that castings ejected on our Chalk Downs suffer
some loss by the percolation of their finer
matter into the chalk. But such impure
superficial 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 percola-
tion, some fine earth is certainly washed
down the sloping grass-covered surfaces of
our Downs. The washing-down process, how-
ever, will be checked in the course of time ;
for although I do not know how thin a layer
of mould suffices to support worms, yet a limit
must at last be reached ; and then their cast-

Chap. YI. MOULD OYEK THE CHALK. 301

ings 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 ai
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, wdiich transversely was almost level
and about 50 yards across. In the bottom,
the mean thickness of the mould from five
measurements was 83 inches; whilst on the
sides of the valley, where the inclination
varied between 14° and 20°, its mean thick-
ness was rather less than 3*5 inches. As the
turf-covered bottom of the valley sloped at an
angle of only between 2° and 3°, it is probable
that most of the 8*3-inch layer of mould had
been washed down from the fianks of the
valley, and not from the upper part. But as
a shepherd said that he had seen water flow-
ing in this valley after the sudden thawing of
snow, it is possible that some earth may have
been broTight down from the upper part ; or,
on the other hand, that some may have been

302 DENUDATION OF THE LAND. Chap. YI.

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
827 feet in height, and consists of a steep
cone of chalk about i 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
upwards, 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
fortified 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 9^
iiiches. On the embankment itself the mould
was only 1 to l^ inch in thickness; and
within the ditch at the bottom it varied from
2|- to 3|, but was in one spot 6 inches in

Chap. VI. MOULD OVEK THE CHALK. 303,

thickness. On the north-west side of the
hill, either no embankment had ever been
thrown up above the ditch, or it had subse-
quently 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 con-
tained fragments of chalk and flint which
had obviously rolled down at different times
from above. The interstices in the under-
lying fragmentary 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
24°. the mould was very thin, namely from
1| to 2| inches; whilst near the base, where
the slope was only 3° to 4°, it increased to
between 8 and 9 inches in thickness. We
may therefore conclude that on this artificially
modified hill, as well as in the natural valleys
of the neighbouring Chalk Downs, some fine
earth, probably derived in large part from

304 DENUDATION OF THE LAND. Chap. VI.

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 Ox
the chaJk through atmospheric and other
agenoieis.

CHAPTER YII.

COXCLUSIOX.

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 remaina
— In the preparation of the soil for the growth of plants —
Mental powers of worms — Concljsion.

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,

306 CONCLUSION. Chap. VI

and the particles composing it are thus
rubbed together. By these means fresh sur-
faces are continually exposed to the action of
the carbonic acid in the soil, and of the
humus-acids which appear to be still more
efficient in the decomposition of rocks. The
generation of the humus-acids is probably
hastened during the digestion of the many
half-decayed leaves which worms consume.
Thus the particles of earth, forming the
superficial mould, are subjected to conditions
eminently favourable for their decomposition
and disintegration. Moreover, the particles
of the softer rocks suffer some amount of
mechanical trituration in the muscular giz-
zards 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 herbage, and where tlio

Chap. YII. CONCLUSION. 307

climate is humid so that much dust cannot be
blown away it appears at first sight im-
possible that there should be any appreciable
amount of subaerial denudation ; but worm-
castings are blown, especially whilst moist
and viscid, in one uniform direction by the
|.>revalent winds which are accompanied by
rain. By these several means the superficial
mould is prevented from accumulating 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
insignificant. 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
9° 26', 2*4 cubic inches of earth which had
been ejected by worms crossed, in the course

308 CONCLUSION, Chap. VIL

of a year, a liorizontal 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 Hi pounds. Thus
a considerable weight of earth is continually
moving down each side of every valley, and
will in time reach its bed. Finally this earth
will be transported by the streams flowing in
the valleys into the ocean, the great receptacle
for all matter 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 aver-
age be lowered '00263 of an inch each year ;
and this would suffice in four and 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 geologist considers ex-
tremely long.

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

Chap. VII. CONCLUSION. 309

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 tesselated 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 cul-
tivated. The old tesselated pavements have,
however, often suffered by having subsided
unequally from being unequally undermined
by the worms. Even old massive walls may
be undermined and subside ; 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
peiiodically expose the mould to the air, and
sift it so that no stones larger than the par-

310 CONCLUSION. Cbap. YH

tides whicli 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
Bubsiances, as well as for the process of nitri-
fication. The bones of dead animals, the
harder parts of insects, the shells of land-
molluscs, leaves, twigs, (5^c., are before long
all buried beneath the accumulated castings of
worms, and are thus brouglit in a more or
less decayed state within reach of the roots
of plants. Worms likewise drag an infinite
number of dead leaves and other parts of
nlants 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.
"\^on Hen sen* placed two worms in a vessel

♦ ' Zeitschrift fiir wissenschaft. Zoolog.' B, xxviii. 1877, p. 3B0.

Chap. VII CONCLUSION. 311

J 8 inches in diameter, which was filled with
sand, on which fallen leaves were strewed ;
and these were soon dragged into their bur-
rows to a depth of 3 inches. After about G
weeks an almost uniform layer of sand, a
centimeter ('4 inch) in thickness, was con-
verted 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 ; notwith-
stsinding that the viscid castings piled over
the mouths of the burrows prevent 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 considerable depth beneath accumulated
castings lie dormant, until at some future
time they are accidentally uncovered and
germinate
21

312 CONCLUSION. Chap. VII.

Worms are poorly provided with sense-
organs, for they cannot be said to see,
although 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 ap-
parently 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, triangles 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

Chap. YII. CONCLUSION. 313

foot-stalks, unless the basal part of the blade
is as narrow as the apex, or narrower than it.

When we behold a wide, turf-covered
expanse, 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
continues 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.

A-binger, Eoman villa at, 178

• castings from Roman villa, with rounded

particles, 258
Acids of humus, action on rocks, 240
Africa, dust from, 235
Air, currents of, worms sensitive to, 28
Amount of earth brought to the surface by worms, 129
Ants, intelligence of, 93
Archiac, T)\ criticisms on my views, 4
Artemisia, leaves of, not eaten by worms, 33
Ash-tree, petioles of, 79

Beaulieu Abbey, burial of the old pavement, 193

castings from, with rounded particles,

255

Beaumont, ]6lie de, on vegetable mould, 2

■ ' *^e rubbish underlying great cities,

178

the transport of dust, 237

■ ■ the permanence of mould, 289

the permanence of ancient tumuli, 290

Beech-forests, stones not buried uuder by castings, 144

Bengal, worms of, 123

Bones, crushed, burial of, under castings, 146

Brading, Koman villa at, 199

, castings from, with rounded particles, 264

316 INDEX.

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,

176
Burrows, depth of, 109
direction of, on a slope, 270

excavation of, 98

lined with black earth, 111

lined with leaves, 112

mouths of, worms lie motionless near, 15

old, their collapse, 118

— plugged up, 58

terminating in a small chamber, often lined wit^h

stones or seeds, 114

Calciferous glands, 17, 43
Cannibal worms, 36
Carnagie, Mr., depth of burrows, 114
Castings, acid, 52

from Beaulieu, 101

■ tower-like, near Nice, 106

ejection of, 116

tower-like, from near Calcutta, 123

of great size on the Nilgiri Mountains, 126

weight of, from a single burrow and from a given

area, 160

_ thickness of layer formed from, during a year, 169

ejected over ancient buildings, 253

flowing down slopes, 261

washed away, 272

■ — dry, disintegration of, 275

blown to leeward, 283

Cells, free, with calcareous matter in the calciferous

glands, 47
Cellulose, digestion of, 37

INDEX. 317

Chalk-formation, surface of, much denuded, 137
Clialk, residue of, forming a superficial deposit, 138

fragments of, soon buried and corroded, 139

formation of mould over, 297

Ched worth, Eoman villa of, 197
Circular trenches near Stonehenge, 287
Claparede, structure of the intestines of worms, 19

on the salivary glands of worms, 42

on the calciferous glands, 44

■ the pharynx adapted for suction, 56

doubts whether earth serves worms as food,,

102, 105

on the gizzards of worms, 246

Clematis, petioles of, used in plugging up burrows, 58,

77
Cobra-snake, intelligence of, 94
Collapsing of old burrows, 118
Concluding remarks, 305
Concretions of lime in the anterior calciferous glands, 45*

calcareous, use of, 54

Corals, mud derived from, 256

Corniche Eoad, disintegrated castings on, 276, 281

Croll, Mr., on denudation, 233

Crowns or ridges on old ploughed fields, 292

Currents of air, worms sensitive to, 28

Dancer, Mr., on the action and number of worms, 146,

159
Deafness of worms, 26

Debris, over the Eoman remains at Silchester, 201
Decay of leaves not hastened by the secretion with which

they are bathed, 38
I^enudation of the land, 230
Depth to which worms burrow, 109
Ligaster, 246

318 INDEX.

Digestion of worms, 37

exti a-stomachal, 43

Disintegration of rocks, aided by worms, 240

Distribution of worms, 120

Down, amount of earth here brought annually to Uie

surface, 137
Downs near Winchester, valleys in, 301
Dust, distance transported, 235-237

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

amount of, which flows down a given slope, 266

swallowed as food, 100

weight of, ejected from a single burrow, 160

Eisen, number of species of worms, 9

depth of burrows, 110

Ejection of castings, 116
Embankments on hill-sides, 278, 282
Encampmeuts, ancient, 290
Ernst, Dr., on worms at Caracas, 121
Excavation of the barrows, 98

Fabre, M., on the instincts of Sphex, 93

Farrer, Mr. T. H., on the Koman villa at Abinger,

178-188
Fat eaten by worms, 36
Fields formerly ploughed, 292
Fish, Mr., criticisms on my views, 6
Flints, standing vertically in the residue over the chalk,

138
acted on externally and internally by atmospheric

agencies, 245
Flowing down of castings, 261
Fluid, digestive, of worms, 37

INDEX. 319

Food of worms, leaves, 35

earth, 100

Foster, Michael, on the pancreatic ferment, 37
on the acidity of the contents of the

intestines, 52
Foundations, deep, of the Eoman buildings at Wroxeter,

227
Furrows on old ploughed fields, 292

Galton, Mr., on the number of dead worms, 14
Geikie, Archibald, on Denudation, 238

controverts E. de Beaumont's views on

Denudation, 289

, James, controverts Richthofen's views, 237

on glaciated rocks, 245

Geographical distribution of worms, 120
Gizzards of worms, 246
Glands, calciferous, 17, 43

function of, 49

Glen Roy, evidence of rarity of debacles, 260

Haast, Von, on aboriginal instruments in New Zealand

found buried, 147
Hearing, sense of, 26
Heat, perception of, 25
Heaths, inhabited by few worms, except where patha

cross them, 10
Hensen on the number of worms in gardens, 5

on worms not subsisting on earth, 108

depth of burrows, 110

on number of worms living in a given area, 158

on the composition of mould, 238

— on the amount of humus formed by two

worms, 310

320 INDEX.

HensloWj Prof., on ledges on hill-sides, 278
Hoffineister, number of species of worms, 9

on worms liybernating in company, 34

perception of light by worms, 20, 22

on the enemies of worms, 62

— depth of burrows, 110

on hybernation of worms, 114

Hooker, Sir J., on ledges of earth on the Himalaya, 278
Humus acids, action of on rocks, 240, 244

Instinct of worms, 35
Intelligence of worms, 35, 64
Intestines of worms, their contents acid, 51
Islands, inhabited by worms, 120

Johnson, Dr. H., on the Eoman remains at "Wroxcter,
222-228

on ammonia in worm-castings, 242

Johnson, S. W., ' How Crops Feed,' 242
Joyce, Rev. J. G., on the Eoman remains at Silchester, 201
Jiilien, Mr. A. A., on the composition of peat, 238
on the humus acids, 240, 244

Key, Eev. H., on the burial of cinders by worms, 146
King, Dr., on the formation of mould in forests in
France, 5

on castings near Kice, 106, 117

on great castings on the Nilgiri MouDtainfl

and in Ceylon, 126

weight of castings near Nice, 163

on disintegrated castings on the Corniche

road, 276, 281

on the washing away of the castings r^n the

Nilgiri Mountains, 274

INDEX. S2I

Knole Park, beech- woods, worms absent, 12
Koninck, De, on the disintegration of rocks, 235

Laburnum leaves, 67

Land, denudation of, 230

Lankester, Eay, on the structure of worms, 18

on worms from Kerguelen Land, 121

La Plata, dust storms of, 236

Layard, Mr., on the habits of the cobra, 94

Leaves, worms distinguish the taste of different kinds, 82

consumed by worms, 35

their decay not hastened by the alkaline secretion

with which they are bathed, 38

decayed, generate acids, 50

used in plugging up burrows, 65

used to line burrows, 112

Ledges of earth on hill- sides, 278
Leon, R, on the digestive fluid of worms, 38
Light, perception of, by worms, 20
Lime, carbonate, concretions of, 45

Maer Hall, amount of earth brought to surface, 130
Mallett, Mr,, on the sinking of the ground under great

buildings, 158
Meat, raw, eaten by worms, 36
Mental qualities of worms, 34
Mint, leaves of, only nibbled, 33
Mississippi, drainage area of, 233
Mobius on the habits of a pike, 94
Moniligaster, 246

Morren on worms surviving long immersion, 13
'■ — on worms lying motionless near mouths of their

burrows, 15

822 INDEX.

MorrcD on worms eating sugar, 36

on the disappearance of the calciferous glands

during winter, 48

on stones in tlie gizzards of worms, 247, 249

Mould, thickness of, annually ejected by worms, 169

thickness of, over Koman remains at Ohedworlli,

199
nature and thickness of, over the Koman remains

at Silchester, 218

' thickness of, at Wroxeter, 223

formation and thickness of, over the chalk, 297

Mountains, worms absent from, 12

Miiller, Fritz, on the worms in' South Brazil, 121

Nice, castings near, 106

disintegrated castings near, 276

Night, worms leave their burrows, 14
Nilgiri Mountains, castings on, 126

Objects strewed on the surface soon buried under cast

ings, 130
Obliteration of old furrows on ploughed land, 292
Odours, degree of sensitiveness to, by worms, 29

Pancreatic secretion, 37

■ not acid, 53

Paper, triangles of, 82

Path, paved, burial of, by worm-castings, 146

Paths inhabited by worms, 10

Pavement, modern, undermined by worms, 192

Pavements, ancient, subsidence of, at Silchester, 212

Peat, formati'.m of, 239

Percolation of earth into the chalk, 297

INDEX. 323

Perichaeta, naturalized near Nice, 106
Perrier, worms surviving long immersion, 13

on tlie calciferous glands, 44

— — on tlie action of the pharynx, 56

on the burrowing power of worms, 99

on naturalized worms, 106

on worms killed by acetic acid, 159

on the gizzards of worms, 246, 249

Petioles of Clematis, 77

of the ash, 79

Pharynx, action of, 56

Pike, stupidity of, 94

pine-leaves used in plugging up burrows, 58, 70

lining burrows, 112

Pipes, formation of, in the chalk, 137
Playfair on Denudation, 290
Ploughed fields, old, 292
Plugging up of the burrows, 58

■ use of the process, 62

Prehension, power of, by worms, 56

Qualities, mental, of worms, 34

Ramsay, Mr., on the sinking of a pavement undermined by
worms, 192

on Denudation, 231

Remains, ancient, buried by worms, 176

Rhododendron leaves, 69

Eichthofen on dust deposits in China, 237

Eobinia, petioles of, 81

Hocks, disintegration of, aided by worms, 240

triturated in the gizzards of worms, 249

Eolling down of dry castings, 275

Romanes, Mr., on the intelligence of animals, 95

324 INDEX.

Sachs on living roots corroding rocks, 243

Sage, leaves of, not eaten by worms, 33

Saliva, doubtful whether any secreted by worms, 42

Saussure, H. De, on brick-pebbles, 254

Schmulewitsch on the digestion of cellulose, 37

Scott, Mr. J., on worms near Calcutta, 123

Seeds preserved in the burrows of worms, 115

Semper on various animals swallowing sand, 102

Senses of worms, 19

Silchester, old Roman town, 201

Silica, colloid, acted on by the humus acids, 242

Sinking of the pavemente at Silchester, 212

Sites inhabited by worms, 9

Smell, sense of, 29

Social feelings of worms, 34

Sorby, Mr., on the trituration of small particles of

rock, 257
Starch eaten by worms, 36
digestion of the granules in the cells of leaves,

41
St. Catherine's Hill, near Winchester, 302
Stones, great, undermined by worms at Leith Hill and at

Stonehenge, 148

■ small, heaped over burrows, 60

small, in the gizzards of worms, 247

rounded in tlie gizzards of worms, 249

Stonehenge, great stones of, undermined by worms,

154

circular trenches near, 287

Structure of worms, 16

Subsidence of the pavements at Silchester, 212

Suction, power of, 56

Sugar eaten by worms, 36

Summary of whole book, 305

Surface, objects strewed on, buried under castings, 130

INDEX. 325

Taste, power of, 32

Thickness of the layer of mould annually ejected by

worms, 169

' of the mould over the remains at Ched worth, 199

— ^ of the mould over the remains at Silchester, 218

— of the mould over the Roman remains at

Wroxeter, 223
Thyme, leaves of, not eaten by worms, 38
Touch, worms highly sensitive to, 28
Triangles of paper, 82
Trituration of particles of reck in the gizzards of wormSj

249
Tumuli, ancient, 290
Tylor, Mr. A., on Denudation, 233
Tylor, Mr. E., on anciently ploughed land, 293
Typhosolis, 19

Utricularia, bladders of, 109

Vibrations, worms sensitive to, 27
Vision, power of, in worms, 20

Walls, ancient, at Abinger, penetrated by worms, 188

penetrated by worms at Silchester, 209

Washing away of castings, 272

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

Weight of earth ejected from a single burrow, 160

Whitaker, Mr., on Denudation, 232

White, on worms leaving their burrows at night, 14

Winchester, chalk formation near, 301

Wind, action of, on castings, 283

Worms, nocturnal, 13

large numbers occasionally die, 14

dead eaten by other worms, 36

326 INDEX.

Worms, contents of intestines, acid, 51

their castings, acid, 52

power of suction, 56

plugging up their burrows, 58

— intelligence of, 64

— formation of their burrows, 98

number of, living in a given area, 158

penetrating ancient walls, 188, 209

gizzards of, and the trituration of the contained

stones, 246

prefer to live in fine earth, 291

Wright, Mr., on the age of Wroxeter, 221
Wroxeter, old Eoman to^n of, 221

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