stone of large size and of irregular shape is left on the surface of
the ground, it rests, of course, on the more protuberant parts; but
worms soon fill up with their castings all the hollow spaces on the
lower side; for, as Hensen remarks, they like the shelter of stones.
As soon as the hollows are filled up, the worms eject the earth which
they have swallowed beyond the circumference of the stones; and thus
the surface of the ground is raised all round the stone. As the
burrows excavated directly beneath the stone after a time collapse,
the stone sinks a little. Hence it is, that boulders which at some
ancient period have rolled down from a rocky mountain or cliff on to a
meadow at its base, are always somewhat imbedded in the soil; and,
when removed, leave an exact impression of their lower surfaces in
the under-lying fine mould. If, however, a boulder is of such huge
dimensions, that the earth beneath is kept dry, such earth will not be
inhabited by worms, and the boulder will not sink into the ground.
A lime-kiln formerly stood in a grass-field near Leith Hill Place, in
Surrey, and was pulled down 35 years before my visit; all the loose
rubbish had been carted away, excepting three large stones of
quartzose sandstone, which it was thought might hereafter be of some
use. An old workman remembered that they had been left on a bare
surface of broken bricks and mortar, close to the foundations of the
kiln; but the whole surrounding surface is now 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
largest, was 64 inches long, 17 inches broad, and from 9 to 10 inches
in thickness. Its lower surface was somewhat protuberant in the
middle; and this part still rested on broken bricks and mortar,
showing the truth of the old workman's account. Beneath the brick
rubbish the natural sandy soil, full of fragments of sandstone, was
found; and this could have yielded very little, if at all, to the
weight of the stone, as might have been expected if the sub-soil had
been clay. The surface of the field, for a distance of about 9 inches
round the stone, gradually sloped up to it, and close to the stone
stood in most places about 4 inches above the surrounding ground. The
base of the stone was buried from 1 to 2 inches beneath the general
level, and the upper surface projected about 8 inches above this
level, or about 4 inches above the sloping border of turf. After the
removal of the stone it became evident that one of its pointed ends
must at first have stood clear above the ground by some inches, but
its upper surface was now on a level with the surrounding turf. When
the stone was removed, an exact cast of its lower side, forming a
shallow crateriform hollow, was left, the inner surface of which
consisted of fine, black mould, excepting where the more protuberant
parts rested on the brick-rubbish. A transverse section of this stone,
together with its bed, drawn from measurements made after it had been
displaced, is here given on a scale of 1/2 inch to a foot (Fig. 2). The
turf-covered border which sloped up to the stone, consisted of fine
vegetable mould, in one part 7 inches in thickness. This evidently
consisted of worm-castings, several of which had been recently
ejected. The whole stone had sunk in the thirty-five years, as far as
I could judge, about 11/2 inch; and this must have been due to the
brick-rubbish beneath the more protuberant 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.
[Illustration: FIG. 2.
Transverse section across a large stone, which had lain on a
grass-field for thirty-five years. _aa_, general level of the
field. The underlying brick of rubbish has not been represented.]
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 upwardly 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 21/2 inches, but in one place it was as much as 51/2. Its average
height close to the stone was probably about 3 inches, and it thinned
out to nothing. If so, a layer of fine earth, 15 inches in breadth and
11/2 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 castings 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 favorable 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 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 conclusion, the raised
surrounding border of turf was only 1 inch high in some parts, and
2 inches in other parts. There were no colonies of ants beneath this
stone, and on digging a hole where 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 feet long, 6 feet broad, and
281/2 inches thick, a hole was dug; and here the vegetable mould was at
least 91/2 inches in thickness. At this depth a flint was found, and a
little higher up on one side of the hole a fragment of glass. The base
of the stone lay about 91/2 inches beneath the level of the surrounding
ground, and its upper surface 19 inches above the ground.
A hole was also dug close to a second huge stone, which in falling had
broken into two pieces; and this must have happened long ago, judging
from the weathered aspect of the fractured ends. The base was buried
to a depth of 10 inches, as was ascertained by driving an iron skewer
horizontally into the ground beneath it. The vegetable mould forming
the turf-covered sloping border round the stone, on which many
castings had recently been ejected, was 10 inches in thickness; and
most of this mould must have been brought up by worms from beneath its
base. At a distance of 8 yards from the stone, the mould was only
51/2 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
contour of the projecting parts and of the adjoining ground, which was
not quite level, was thus ascertained, as shown in the accompanying
diagram (Fig. 3) on a scale of 1/2 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 21/2 inches above the general level. A hole
was dug on the eastern side, and the base of the stone was here found
to lie at a depth of 4 inches beneath the general level of the
ground, and of 8 inches beneath the top of the sloping turf-covered
border.
[Illustration: FIG. 3.
Section through one of the fallen Druidical stones at Stonehenge,
showing how much it had sunk into the ground.]
Sufficient evidence has now been given showing that small objects left
on the surface of the land where worms abound soon get buried, and
that large stones sink slowly downwards through the same means. Every
step of the process could be followed, from the accidental deposition
of a single casting on a small object lying loose on the surface, to
its being entangled amidst the matted roots of the turf, and lastly to
its being embedded in the mould at various depths beneath the surface.
When the same field was re-examined after the interval of a few years,
such objects were found at a greater depth than before. The
straightness and regularity of the lines formed by the embedded
objects, and their parallelism with the surface of the land, are the
most striking features of the case; for this parallelism shows how
equably the worms must have worked; the result being, partly the
effect of the washing 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 sub-stratum, which at Leith Hill Place was sandy
soil including many bits of rock, and at Stonehenge, chalk-rubble with
broken flints; considering, also, the presence of the turf-covered
sloping border of mould round the great fragments of stone at both
these places, their sinking does not appear to have been sensibly
aided by their weight, though this was considerable.
_On the number of worms which live within a given space._--We will
now show, first, 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 land, or 53,767 in an acre. This latter number of worms
would weigh 356 pounds, taking Hensen's standard of the weight of a
single 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 water in which
worms were immersed, invariably killed them quickly. On the morning
after the barrels had been upset, "the heaps of worms which lay dead
on the ground were so amazing, that if Mr. Miller had not seen them,
he could not have thought it possible for such numbers to have existed
in the space." As further evidence of the large number of worms which
live in the ground Hensen states that he found in a garden 64 open
burrows in a space of 141/2 square feet, that is, 9 in 2 square feet.
But the burrows are sometimes much more numerous, for when digging in
a grass-field near Maer Hall, I found a cake of dry earth, as large as
my two open hands, which was penetrated by seven burrows, as large as
goose-quills.
[Illustration]
TWO FOPS AMONG THE FISHES
(FROM GLEANINGS FROM NATURE.)[7]
BY W. S. BLATCHLEY.
[7] Copyright by W. S. Blatchley, 1899.
I.--THE RAINBOW DARTER.
"Little fishy in the brook."
[Illustration]
Not the one "daddy caught with a hook," but another, too small for the
hook, too small for the frying-pan, too small for aught else but
beauty, and gracefulness of form; and yet not the young of a larger
fish, but full grown of himself. In every brook in the State he may be
found, yea, even in the rill, no more than a foot in width, which
leads away from the old spring-house on the hillside. You will not
find him swimming about like the minnows in the still, deep water of
the stream, but where the clear, cold water is rushing rapidly over
the stones of a ripple he makes his home. There he rests quietly on
the bottom, waiting patiently for his food, the larvae or young of
gnats, mosquitoes, and other such insects, to float by.
If you attempt to catch him, or your shadow suddenly frightens him,
with a sweep of his broad pectoral or breast fins, he moves quicker
than a flash a few feet farther up the stream, and then as suddenly
comes to a stop, and resumes his quiet, "thoughtful" attitude. If you
persist in your attempt to capture him, he will dart under a small
stone or submerged leaf, where, like the foolish ostrich which when
pursued hides her head under her wing, no longer seeing you, he thinks
himself secure.
[Illustration: RAINBOW DARTER.]
On account of the shape of his body, as well as on account of his
rapid movements, he has received the surname "darter." Belonging to
the group which bears this surname, there are, in the eastern half of
the United States, about forty-seven species or kinds, the largest of
which, when full grown, measures only about six inches in length,
while the smallest species never reaches a length of more than an inch
and a half. They all have the same habits, and at least twenty-nine
kinds of them are found in Indiana; but the one of which I am writing
is much the more common. He is from two to two and a half inches in
length, and, like the other members of his family, has two fins on his
back; "dorsal" fins they are called by naturalists, the front one of
which contains ten short spines. During eight months of the year, the
males and females dress alike in a suit of brownish olive which is
striped on the sides with ten or twelve narrow, black cross-bars, and
more or less blotched on the back with darker spots. But on the first
warm days of spring, when the breezes blow up from the gulf, awakening
the gypsy in our blood, the little male fish feels, too, their
influence, and in him there arises an irresistible desire to
"a-courting go." Like most other beings of his sex, he thinks his
every-day suit too plain for the important business before him. It
will, in his opinion, ne'er catch the eye of his lady love. So he dons
one of gaudy colors and from it takes his name,--the rainbow
darter,--for in it he is best known, as it not only attracts the
attention of his chosen one, but often also that of the wandering
naturalist who happens along the stream.
The blackish bars of other seasons are changed to indigo blue, while
the space between them assumes a hue of the brightest orange. The fins
are broadly edged with blue and have the bases orange, or orange and
scarlet, while the cheeks assume the blue and the breast becomes an
orange. Clad in this suit he ventures forth on his mission, and if
successful, as he almost always is, the two construct a nest of tiny
stones in which the eggs of the mother-fish are laid and watched over
with jealous care by both parents until in time there issue forth sons
destined some day to wear a coat of many colors, and "darters" to be
attracted by those coats, as was their mother by the one their father
wore.
Although so abundant and so brilliant in the springtime, the rainbow
darter is known to few but naturalists. The fishes in which the
average country boy is interested are the larger ones--such as the
goggle-eye, the sucker, chub, and sunfish--those which, when caught,
will fill up the string and tickle the palate.
But there are, let us hope, among our farmers' sons and daughters,
some who are learning to take an interest in the objects of nature
which are beautiful, as well as in those which are useful. To them I
will say, if you wish to see something really pretty, make a seine
from an old coffee sack or a piece of mosquito netting, and any day in
spring drag two or three ripples of the branch which flows through the
wood's pasture, and ten chances to one you will get some "rainbows."
By placing them in a fruit jar three-fourths full of clear, cold
water, and renewing the water every few hours, they can be kept for
several days; but they cannot bear the confinement long, accustomed as
they are to the free running stream from which they were taken.
By taking the rainbow as the type of the darter and studying closely
its habits, both in captivity and in the streams, much can be learned
about a group which, in the words of Dr. S. A. Forbes, "are the
mountaineers among fishes. Forced from the populous and fertile
valleys of the river beds and lake bottoms, they have taken refuge
from their enemies in the rocky highlands where the free waters play
in ceaseless torrents, and there they have wrested from stubborn
nature a meagre living. Although diminished in size by their
continual struggle with the elements, they have developed an activity
and hardihood, a vigor of life and a glow of high color almost unknown
among the easier livers of the lower lands."
II.--THE LONG-EARED SUNFISH.
Among the most brightly colored of all the fresh-water members of the
finny tribe is the long-eared sunfish. When full grown its length is
about eight inches and the breadth one-half as much. The color is then
a brilliant blue and orange, the former predominating above; the
orange on the sides in spots, the blue in wavy, vertical streaks. The
cheeks are orange with bright blue stripes; the fins with the
membranes orange, and the rays blue. Extending back from the hind
margin of each cheek is a conspicuous blackish membrane termed an
"ear-flap," which in this species is longer than in any other of the
sun-fish family, whence the specific name, _megalotis_, from two Greek
words meaning "great" and "ear."
[Illustration: LONG-EARED SUNFISH.]
Within the placid pools of the brooks and larger streams of the State
this sunfish has its favorite haunts. Mid-summer is the time when its
habits can be best observed. On a recent August morn I sat for an
hour or longer on the banks of a stream, which flows through a wooded
blue-grass pasture, and watched the denizens of its waters. A peaceful
calm existed, the water being without a ripple and with scarce the
semblance of a flow--the air without the shadow of a breeze. Dragon
flies lazily winged their way across the pool, now resting daintily
upon a blade of sedge or swamp grass, now dipping the tips of their
abdomens beneath the surface of the water while depositing their eggs.
The only sounds of nature were the buzz of a bumble-bee feeding among
the flowers of the _Brunella_ at my side, and an occasional drawl of a
dog-day locust from the branches of the sycamore which threw a
grateful shade about me.
The sunfish "hung motionless" in the water, their heads towards me,
holding their position only by a slow flapping of their dorsal and
pectoral fins. Their nesting time over, their season's labor ended, it
was with them, as with many other beings, a time of languor.
These long-eared fishes are the lords and ladies of the respective
pools wherein they abide. When they move other smaller fry clear the
way. If a worm or gnat, falling upon the surface, tempts them, it is
theirs. A leaf falls near them and is seemingly unnoticed--a fly, and
how quickly their dormant energy is put into motion. With a dart and a
gulp the insect is swallowed, and a new stage of waiting expectancy is
ushered in.
How admirably fitted their form for cleaving the water! They often
seem to glide rather than propel themselves through its depths. Again,
how swiftly the caudal fin moves when with straight unerring motion
they dart upon their prey. At times one turns his body sideways, and,
with a slow, upward-gliding motion, moves toward some object on the
surface which is doubtfully "good to eat." He even takes it into his
mouth and then, not having faith in his power to properly digest it,
ejects it with force, and turning quickly darts back to the friendly
shadow of a boulder beneath whose sides he has, in time of threatened
danger, a safe retreat.
I throw a grasshopper into the pool. Like a flash six of the sunfish
are after it. One reaches it a tenth of a second in advance of the
others, and with a lightning-like gulp, which disturbs the serenity of
the surface of the pool, swallows the kicking prey. The energy of the
sun's heat and light, stored in grass, transmitted to move muscles in
gigantic leaps, will, in a short time, wag a caudal fin and propel the
owner through these watery depths.
Years are thus doubtless spent by these long-eared sunfish in a dreamy
sort of existence, their energies quickened by the vernal season and
growing duller on the approach of winter. Excepting the times when
they are tempted by a wriggling worm on some boy's hook, theirs is a
life exempt from danger. A kingfisher glancing down from his perch on
the bent sycamore limb may, at times, discern them and lessen their
ranks; but, methinks, the chub minnows, with fewer spines in their
dorsal fins, are more agreeable to the king-fisher's palate. With all
the tints of the rainbow gleaming from their sides they move to and
fro, the brilliant rulers of these quiet pools.
The king or monarch of those noted was most gorgeously arrayed. In
addition to the hues above described, a streak of emerald bordered his
dorsal and caudal fins and was bent around the edge of his upper
lip--a green mustache, as it were. By tolling them with occasional
bits of food I drew him and his retinue close into shore. There, for
some time they rested, watching eagerly for additional morsels. As I
was leaving I plucked from my sleeve an ant and threw it towards them.
A dart, a gurgle, a gulp--the leader had leaped half his length from
the water, and the ant was forever gone. The ripples receded and
finally disappeared, and the last scene in this tragedy of nature was
at an end.
[Illustration]
SEA-SLUGS AND CUTTLE-FISH
(FROM A JOURNAL OF RESEARCHES.)
BY CHARLES DARWIN.
[Illustration: CUTTLE-FISH.]
I was much interested, on several occasions, by watching the habits of
an Octopus, or cuttle-fish. Although common in the pools of water left
by the retiring tide, these animals were not easily caught. By means
of their long arms and suckers, they could drag their bodies into very
narrow crevices; and when thus fixed, it required great force to
remove them. At other times they darted, tail first, with the rapidity
of an arrow, from one side of the pool to the other, at the same
instant discoloring the water with a dark chestnut-brown ink. These
animals also escape detection by a very extraordinary, chameleon-like
power of changing their color. They appear to vary their tints
according to the nature of the ground over which they pass: when in
deep water, their general shade was brownish-purple, but when placed
on the land, or in shallow water, this dark tint changed into one of
a yellowish green. The color, examined more carefully, was a French
gray, with numerous minute spots of bright yellow: the former of these
varied in intensity; the latter entirely disappeared and appeared
again by turns. These changes were effected in such a manner, that
clouds, varying in tint between a hyacinth red and a chestnut brown,
were continually passing over the body. Any part, being subjected to a
slight shock of galvanism, became almost black: a similar effect, but
in a less degree, was produced by scratching the skin with a needle.
These clouds, or blushes as they may be called, are said to be
produced by the alternate contraction and expansion of minute
vescicles containing variously colored fluids.