Let us open the Spider’s cabin. What luxury! We have read how
the Princess in the fairy-tale was unable to rest, if there was a
crumpled rose-leaf in her bed. The Clotho is quite as fastidious. Her couch
is more delicate than swan’s-down and whiter than the fleece of
clouds where brood the summer storms. It is the ideal blanket. Above is
a canopy or tester of equal softness. Between the two nestles the
Spider, short-legged, clad in somber garments, with five yellow favors on
her back.
Rest in this exquisite retreat demands that it be perfectly
steady, especially on gusty days, when sharp draughts creep under the
stone dwelling. By taking a careful look at her we can see how the
Spider manages this. The arches that bear the weight of the building
are fastened to the stone at each end. Moreover, where they touch, you
may see a cluster of diverging threads that creep along the stone and
cling to it throughout their length, which spreads afar. I have measured
some that were fully nine feet long. These are so many cables; they are
like the ropes and pegs that hold the Arab’s tent in position.
Another
detail attracts our attention: whereas the inside of the house is exquisitely
clean, the outside is covered with dirt, bits of earth, chips of rotten wood,
little pieces of gravel. Often there are worse things still: hung up or
embedded are the dry carcasses of Beetles that favor under-rock shelters;
parts of Thousand-legged Worms, bleached by the sun; snail-shells, chosen
from among the smallest.
These relics are plainly, for the most part,
table-leavings, broken victuals. Unskilled in laying traps, the Clotho lives
upon the insects who wander from one stone to another. Whoever ventures under
the slab at night is strangled by the hostess; and the dried-up carcass,
instead of being flung to a distance, is hung to the silken wall, as
though the Spider wished to make a bogey-house of her home. But this
cannot be her aim. To act like the ogre who hangs his victim from the
castle battlements is the worst way to disarm suspicion in the passers-by
whom you are lying in wait to capture.
There are other reasons which
increase our doubts. The shells hung up are most often empty; but there are
also some occupied by the Snail, alive and untouched. What can the Spider do
with these snail-shells wherein the animal retreats so far that she cannot
reach it? The Spider cannot break the hard shell or get at the hermit through
the opening. Then why should she collect these prizes, whose slimy
flesh is probably not to her taste? We begin to suspect a simple
question of ballast and balance. The House Spider prevents her web, spun in
a corner of the wall, from losing its shape at the least breath of air, by
loading it with crumbling plaster and allowing tiny fragments of mortar to
accumulate. The Clotho Spider dumps down on her abode any more or less heavy
object, mainly corpses of insects, because she need not look for these and
finds them ready to hand after each meal. They are weights, not trophies;
they take the place of materials that must otherwise be collected from a
distance and lifted to the top. In this way, a breastwork is obtained that
strengthens and steadies the house. Further balance is often given by tiny
shells and other objects hanging a long way down. The Clotho knows the laws
of balancing; by means of additional weights, she is able to lower the center
of gravity and thus to give her dwelling the proper equilibrium and
roominess.
Now what does she do in her softly-wadded home? Nothing, that
I know of. With a full stomach, her legs luxuriously stretched over the
down carpet, she does nothing, thinks of nothing; she listens to the
sound of the earth revolving on its axis. It is not sleep, still less is
it waking; it is a middle state where the Spider is conscious of
nothing except that she is happy. We ourselves, when comfortably in bed,
enjoy, just before we fall asleep, a few moments of bliss, when we
neither think nor worry; and those moments are among the sweetest in our
lives. The Clotho Spider seems to know similar moments and to make the most
of them.
[Illustration]
CHAPTER XXI
THE
SPIDER’S TELEGRAPH-WIRE
Of the six Garden Spiders I have noticed, two
only, the Banded and the Silky Spiders, stay constantly in their webs, even
under the blinding rays of a fierce sun. The others, as a rule, do not show
themselves until nightfall. At some distance from the net they have a rough
and ready retreat in the brambles, a hiding-place made of a few leaves
held together by stretched threads. It is here that they usually remain
in the daytime, motionless and sunk in meditation.
But the shrill
light that vexes them is the joy of the fields. At such time, the Locust hops
more nimbly than ever, more gayly skims the Dragon-fly. Besides, the sticky
web, in spite of the rents suffered during the night, is still in fairly good
condition. If some giddy-pated insect allow himself to be caught, will the
Spider, at the distance whereto she has retired, be unable to take advantage
of the windfall? Never fear. She arrives in a flash. How does she know
what has happened? Let us explain the matter.
It is the vibration of
the web which tells her, rather than the sight of the captured object. To
prove this, I laid upon several Spiders’ webs a dead Locust. I placed the
Locust where the Spider might have plainly seen it. Sometimes the Spider was
in her web, and sometimes she was outside, in her hiding-place. In both
cases, nothing happened at first. The Spider remained motionless, even when
the Locust was at a short distance in front of her. She did not seem to see
the game at all. Then, with a long straw, I set the dead insect
trembling.
That was quite enough. The Banded Spider and the Silky Spider
hastened to the central floor, the others, who were in hiding, came down
from the branch; all went to the Locust, bound him with tape, treated
him, in short, as they would treat a live prey captured under the
usual conditions. It took the shaking of the web to decide them to
attack.
If we look carefully behind the web of any Spider with a
daytime hiding-place, we shall see a thread that starts from the center of
the web and reaches the place where the Spider lurks. It is joined to
the web at the central point only. Its length is usually about
twenty-two inches, but the Angular Spider, settled high up in the trees, has
shown me some as long as eight or nine feet.
[Illustration: “The
slanting cord is a telegraph wire.”]
This slanting line is a foot-bridge
by which the Spider hurries to her web when there is something going on
there, and then, when her errand is finished, returns to her hut. But that is
not all it is. If it were, the foot-bridge would be fastened to the upper end
of the web. The journey would then be shorter and the slope less
steep.
The line starts from the center of the net because that is the
place where the spokes meet and therefore where the vibration from any
part of the net is best felt. Anything that moves upon the web sets
it shaking. All then that is needed is a thread going from this
central point to carry to a distance the news of a prey struggling in some
part or other of the net. The slanting cord is not only a foot-bridge: it
is a signaling-apparatus, a telegraph-wire.
In their youth, the Garden
Spiders, who are then very wide-awake, know nothing of the art of telegraphy.
Only the old Spiders, meditating or dozing in their green tent, are warned
from afar, by telegraph, of what takes place on the net.
To save
herself from keeping a close watch that would be drudgery and to remain alive
to events even when resting, with her back turned on the net, the hidden
Spider always has her foot upon the telegraph-wire. Here is a true story to
prove it.
An Angular Spider has spun her web between two
laurestine-shrubs, covering a width of nearly a yard. The sun beats upon the
snare, which is abandoned long before dawn. The Spider is in her day house, a
resort easily discovered by following the telegraph-wire. It is a
vaulted chamber of dead leaves, joined together with a few bits of silk.
The refuge is deep: the Spider disappears in it entirely, all but
her rounded hind-quarters, which bar the entrance.
With her front half
plunged into the back of her hut, the Spider certainly cannot see her web;
she could not even if she had good sight, instead of being half blind as she
is. Does she give up hunting during this period of bright sunlight? Not at
all. Look again.
Wonderful! One of her hind-legs is stretched outside the
leafy cabin; and the signaling-thread ends just at the tip of that leg.
Whoever has not seen the Spider in this attitude, with her hand, so to
speak, on the telegraph-receiver, knows nothing of one of the most
curious examples of animal cleverness. Let any game appear upon the
scene, and the slumberer, at once aroused by means of the leg receiving
the vibrations, hastens up. A Locust whom I myself lay on the web gives
her this agreeable shock, and what follows? If she is satisfied with
her prey, I am still more satisfied with what I have learned.
One word
more. The web is often shaken by the wind. The signaling-cord must pass this
vibration to the Spider. Nevertheless, she does not leave her hut and remains
indifferent to the commotion prevailing in the net. Her line, therefore, is
something better than a bell-rope; it is a telephone capable, like our own,
of transmitting infinitesimal waves of sound. Clutching her telephone-wire
with a toe, the Spider listens with her leg; she can tell the difference
between the vibration proceeding from a prisoner and the mere shaking caused
by the wind.
[Illustration]
CHAPTER XXII
THE
CRAB-SPIDER
The Banded Spider, who works so hard to give her eggs a
wonderfully perfect dwelling-house, becomes, after that, careless of her
family. For what reasons? She lacks the time. She has to die when the
first cold comes, whereas the eggs are to pass the winter in their cozy
home. She cannot help deserting the nest. But, if the hatching were
earlier and took place in the Spider’s life, I imagine that she would be
as devoted to her family as a Bird is. So I gather from the behavior of
a shapely Spider who weaves no webs, lies in wait for her prey, and
walks sideways, like a Crab.
This Spider with the Crab-like figure
does not know how to make nets for catching game. Without springs or snares,
she lies hidden among the flowers, and waits for the arrival of the prey,
which she kills by a scientific stab in the neck. The particular species I
have observed is passionately fond of the pursuit of the Domestic
Bee.
The Bee appears, seeking no quarrel, intent upon plunder. She
tests the flowers with her tongue; she chooses a spot that will yield a
good return. Soon she is wrapped up in her harvesting. While she is
filling her baskets and distending her crop, the Crab-spider, that
bandit lurking under cover of the flowers, comes out of her
hiding-place, creeps round behind the bustling insect, steals up close, and,
with a sudden rush, nabs her in the nape of the neck. In vain the Bee
protests and darts her sting at random; the assailant does not let
go.
Besides, the bite in the neck is paralyzing, because the
nerve-centers are affected. The poor thing’s legs stiffen; and all is over in
a second. The murderess Spider now sucks the victim’s blood at her
ease and, when she has done, scornfully flings the drained corpse
aside.
We shall see the cruel vampire become a model of devotion where
her family is concerned. The ogre loved his children; he ate the
children of others. Under the tyranny of hunger, we are all of us, beasts
and men alike, ogres.
After all, this cutter of Bees’ throats is a
pretty, a very pretty creature, in spite of her unwieldy body fashioned like
a squat pyramid and embossed on the base, on either side, with a pimple
shaped like a camel’s hump. The skin, more pleasing to the eye than any
satin, is milk-white in some, in others lemon-yellow. There are fine ladies
among them who adorn their legs with a number of pink bracelets and
their backs with crimson patterns. A narrow, pale-green ribbon
sometimes edges the right and left of the breast. The costume is not so
rich as that of the Banded Spider, but much more elegant because of
its soberness, its daintiness, and the artistic blending of its
colors. People who shrink from touching any other Spider do not fear to
handle the beautiful Crab Spider, so gentle in
appearance.
[Illustration]
THE CRAB-SPIDER’S
NEST
Skillful in the prompt despatch of her prey, the little
Crab-spider is no less clever in the nesting art. I find her settled on a
privet in the inclosure. Here, in the heart of a cluster of flowers,
the luxurious creature plaits a little pocket of white satin, shaped like
a wee thimble. It is the receptacle for the eggs. A round, flat lid, of
a felted fabric, closes the mouth.
Above this ceiling rises a dome of
stretched threads and faded flowerets which have fallen from the cluster.
This is the watcher’s conning-tower. An opening, which is always free, gives
access to this post.
Here the Spider remains on constant duty. She has
thinned greatly since she laid her eggs, has almost lost her figure. At the
least alarm, she sallies forth, waves a threatening limb at the passing
stranger and invites him, with a gesture, to keep his distance. Having put
the intruder to flight, she quickly returns indoors.
And what does she
do in there, under her arch of withered flowers and silk? Night and day, she
shields the precious eggs with her poor body spread out flat. Eating is
neglected. No more lying in wait, no more Bees drained to the last drop of
blood. Motionless, rapt in meditation, the Spider is sitting on her
eggs.
The brooding Hen does likewise, but she is also a
heating-apparatus and, with the gentle warmth of her body, awakens the germs
to life. For the Spider, the heat of the sun is enough; and this alone keeps
me from saying that she “broods.”
For two or three weeks, the little
Spider, more and more wrinkled by lack of food, never relaxes her position.
What is the withered thing waiting for, before expiring? She is waiting for
her children to emerge; the dying creature is still of use to
them.
When the Banded Spider’s little ones come out from their balloon,
they have long been orphans. There is none to come to their
assistance; and they have not the strength to free themselves without help.
The balloon has to split automatically and to scatter the youngsters
and their flossy mattress all mixed up together. The Crab-spider’s
wallet, sheathed in leaves over the greater part of its surface, never
bursts; nor does the lid rise, so carefully is it sealed down.
Nevertheless, after the delivery of the brood, we see, at the edge of the
lid, a small, gaping hole, an exit-window. Who contrived this window,
which was not there at first?
The fabric is too thick and tough to
have yielded to the twitches of the feeble little prisoners. It was the
mother, therefore, who, feeling her offspring shuffle impatiently under the
silken ceiling, herself made a hole in the bag. She persists in living for
five or six weeks, despite her shattered health, so as to give a last helping
hand and open the door for her family. After performing this duty, she
gently lets herself die, hugging her nest and turning into a shriveled
relic. The Hen does not reach this height of
unselfishness!
[Illustration]
THE YOUNG CRAB-SPIDERS
It
is in July that some little Crab-spiders that I have in my laboratory come
out of their eggs. Knowing their acrobatic habits, I have placed a bundle of
slender twigs at the top of the cage in which they were born. All of them
pass through the wire gauze and form a group on the summit of the brushwood,
where they swiftly weave a roomy lounge of criss-cross threads. Here they
stay, pretty quietly, for a day or two; then foot-bridges begin to be flung
from one object to the next. This is the fortunate moment.
I put the
bunch laden with beasties on a small table, in the shade, before the open
window. Soon they begin to spin threads to carry them away, but slowly and
unsteadily. They hesitate, go back, fall short at the end of a thread, climb
up again. In short, much trouble for a poor result.
As matters
continue to drag, it occurs to me, at eleven o’clock, to take the bundle of
brushwood swarming with the little Spiders, all eager to be off, and place it
on the window-sill, in the glare of the sun. After a few minutes of heat and
light, things move much faster. The little Spiders run to the top of the
twigs, bustle about actively. I cannot see them manufacturing the ropes or
sending them floating at the mercy of the air; but I guess their
presence.
Three or four Spiders start at a time, each going her own way.
All are moving upwards, all are climbing some support, as can be told by
the nimble motion of their legs. Moreover, you can see the thread
behind them, where it is of double thickness. Then, at a certain
height, individual movement ceases. The tiny animal soars in space and
shines, lit up by the sun. Softly it sways, then suddenly takes
flight.
What has happened? There is a slight breeze outside. The floating
cable has snapped and the creature has gone off, borne on its parachute. I
see it drifting away, showing, like a spot of light, against the dark foliage
of the near cypresses, some forty feet distant. It rises higher, it crosses
over the cypress-screen, it disappears. Others follow, some higher, some
lower, hither and thither.
[Illustration: “Like the finish of a fireworks
display.”]
But the throng has finished its preparations; the hour has
come to disperse in swarms. We now see, from the crest of the brushwood,
a continuous spray of starters, who shoot up like tiny rockets and
mount in a spreading cluster. In the end, it is like the bouquet at
the finish of a fireworks display, the sheaf of rockets fired all at
once. The comparison is correct down to the dazzling light itself. Flaming
in the sun like so many gleaming points, the little Spiders are the
sparks of that living fireworks. What a glorious send-off! What an
entrance into the world!
Sooner or later, nearer or farther, the fall
comes. To live, we have to descend, often very low, alas! The Spiderling,
therefore, touches land. The parachute tempers her fall. She is not
hurt.
The rest of her story escapes me. What infinitely tiny Midges does
she capture before possessing the strength to stab her Bee? What are
the methods, what the wiles of atom contending with atom? I know not.
We shall find her again in spring, grown quite large and crouching
among the flowers whence the Bee takes
toll.
[Illustration]
CHAPTER XXIII
THE
LABYRINTH SPIDER
While the Garden Spiders are incomparable weavers,
many other Spiders have even more ingenious devices for catching game. Some
of them are real celebrities, who are mentioned in all the
books.
Certain Bird Spiders, or American Tarantulas, live in a burrow
like the Tarantula I have been telling you about, but their burrow is
more perfect than hers. My Tarantula surrounds the mouth of her hole with
a simple curb, a mere collection of tiny pebbles, sticks, and silk;
the American ones fix a movable floor to theirs, a round shutter with
a hinge, a groove, and a set of bolts. When one of these Tarantulas
comes home, the lid drops into the groove and fits so exactly one cannot
tell where it joins. If any one from outside tries to raise the
trap-door, the Spider pushes the bolt,—that is to say, plants her claws
into certain holes on the opposite side to the hinge,—props herself
against the wall, and holds the door firmly.
Another, the Water
Spider, builds herself an elegant silken diving-bell, in which she stores
air. She waits in it for the coming of game and keeps cool meanwhile. On
scorching hot days, hers must be a real palace of luxury, such as men have
sometimes ventured to build under water, with mighty blocks of stone and
marble. Tiberius, the wicked Roman Emperor, had such a submarine palace; but
his is only a hateful memory, whereas the Water Spider’s dainty tower
still flourishes.
If I had had the chance to observe these Spiders, I
should gladly add a few unpublished facts to their life-history; but I must
give up the idea. The Water Spider is not found in my district. The
American Tarantula, the expert in hinged doors, I saw once only, by the side
of a path. I was occupied with something else, and did not give it
more than a passing glance. I have never seen it again.
But it is not
only the uncommon insects that are worth attention. The common ones, if
carefully observed, can tell us things just as important. I am interested in
the Labyrinth Spider, which I find oftener than any other in the fields.
Several times a week, in July, I go to study my Spiders on the spot, early in
the morning, before the sun beats fiercely on one’s neck. The children come
with me, each provided with an orange in case they get thirsty.
We
soon discover high silk buildings, the threads beaded with dew and glittering
in the sun. The children are wonderstruck at those glorious chandeliers, so
that they even forget their oranges for a moment. I am not indifferent to
them, either. Our Spider’s labyrinth is a splendid spectacle. That and the
concert of the Thrushes are worth getting up for.
Half an hour’s heat,
and the magic jewels disappear with the dew. Now is the time to look at the
webs. Here is one spreading its sheet over a large cluster of rock-roses; it
is the size of a handkerchief. Many guy-ropes moor it to the brushwood. It
covers the bush like a piece of white muslin.
The web is flat at the
edges and gradually hollows into a crater, not unlike the bell of a
hunting-horn. At the center is a funnel whose neck, narrowing by degrees, is
eight or nine inches deep and leads back into the leafy thicket.
At
the entrance to the tube sits the Spider, who looks at us and shows no great
excitement at our presence. She is gray, modestly adorned on the thorax with
two black ribbons and on the abdomen with two stripes in which white specks
alternate with brown. She has a sort of double tail at the end of her body, a
rather curious feature in a Spider.
I expected to find, at the bottom of
the Spider’s funnel, a wadded cell where she might rest in her hours of
leisure. On the contrary, there is only a sort of door, which stands always
ajar so that the Spider may escape at any time through the grass and gain the
open.
Above, in the Spider’s web, there is a forest of ropes. It might be
the rigging of a ship disabled by a storm. They run from every twig of
the supporting boughs, they are fastened to the tip of every branch.
There are long ropes and short ropes, upright and slanting, straight
and bent, taut and slack, all criss-cross and a-tangle, to the height
of three feet or so. The whole makes a chaos of netting, a real
labyrinth which none but the very strongest insects can break
through.
There is nothing like the sticky snare of the Garden Spiders
here. The threads are not sticky, but they are very bewildering. See this
small Locust who has lighted on the rigging. He is unable to get a
steady foothold on that shaky support; he flounders about; and the more
he struggles, the more he is entangled. The Spider, looking at him
from her funnel, lets him have his way. She does not run up the ropes;
she waits until the desperate prisoner in his struggles falls on the
main part of the web.
Then she comes, flings herself upon her prey,
and slowly drains his blood. The Locust is lifeless at the first bite; the
Spider’s poison has settled him.
When laying-time is at hand, the
Spider changes her residence; she leaves her web, which is still in excellent
condition; she does not come back to it. The time has come to make the nest.
But where? The Spider knows well; I am in the dark. I spend whole mornings
ransacking the bushes, until at last I learn the secret. The nest is some
distance away from the web, in a low, thick cluster of bushes; it is a
clumsy bundle of dead leaves, roughly drawn together with silk threads.
Under this rude covering is a pouch of fine texture containing the
egg-casket.
[Illustration]
I am disappointed in the appearance of
this Spider’s nest, until I remember that she probably cannot do better in
the places where she builds. In the midst of a dense thicket, among a tangle
of dead leaves and twigs, there is no room for an elegant piece of work. By
way of experiment, I carry half a dozen Labyrinth Spiders into my
laboratory near the laying-time, place them in large wire-gauze cages,
standing in earthen pans filled with sand, with a sprig of thyme planted in
the center to give a support for each nest. Now they will show what
they can do.
The experiment works perfectly. By the end of August I
have six nests, magnificent in shape and of a dazzling whiteness. The Spiders
have had elbow-room, and they have done their best. The nests are ovals of
exquisite white muslin, nearly as large as a Hen’s egg. They are open at
either end. The front-entrance broadens into a gallery; the back-entrance
tapers into a funnel-neck. It is somewhat the same construction as that of
the Labyrinth web. Even the labyrinth is repeated, for in front of the
bell-shaped mouth is a tangle of threads. The Spider has her pattern by
heart, and uses it on all occasions.
This palace of silk is a
guard-house. Behind the soft, milky, partly transparent wall glimmers the
egg-casket, its shape vaguely suggesting the star of some order of
knighthood. It is a large pocket, of a splendid dead-white, with pillars on
every side which keep it motionless in the center of the nest. There are
about ten of these pillars; they are slender in the middle and wider at both
ends. They form corridors around the central room. The mother walks gravely
to and fro under the arches of these corridors, which are like the
cloisters of a nunnery; she stops first here, then there; she listens to
all that happens inside the satin wrapper of her egg-wallet. I would
not disturb her for anything; but I find, from nests I have picked up
in the fields, that the purse contains about a hundred eggs, very
pale amber-yellow beads.
When I remove the outer white-satin wall, I
come upon a kernel of earthy matter, grains of sand mixed with the silk.
However did they get there? Did they soak through the rain-water? No, the
wrapper is spotless white outside. They have been put there by the mother
herself. She has built around her eggs, to protect them from parasites, a
wall composed of a great deal of sand and a little silk.
Inside this
is still another silken wrapper, and then come the little Spiders, already
hatched out and moving about in their nursery.
But, to go back—why does
the mother leave her fine web when laying-time comes, and make her nest so
far away? She has her reason, you may depend upon it. Her large net, like a
sheet, with the labyrinth stretched above, is very conspicuous; parasites
will not fail to come running at this signal, showing up against the green;
if her nest is near, they will certainly find it; and a strange grub,
feasting on a hundred new-laid eggs, will ruin her home. So the wise
Labyrinth Spider shifts her quarters, and goes off at night to explore the
neighborhood for a less dangerous retreat for her coming family. The low
brambles dragging along the ground, keeping their leaves through the winter,
and catching the dead leaves from the oaks hard by, or rosemary tufts,
low and bushy, suit her perfectly. In such spots I usually find her
nest.
Many Spiders leave their nests after they have laid the eggs,
but the Labyrinth, like the Crab-spider, remains to watch over hers.
She does not become thin and wither away, like the Crab-spider. She
keeps her appetite, she is on the lookout for Locusts; and so she builds
a hunting-box, a tangle of threads, on the outside of her nest.
When
she is not hunting, as we have seen, she walks the corridors around her eggs,
she listens to find out if all is well. If I shake the nest at any point with
a straw, she quickly runs up to inquire what is happening. Probably she keeps
off parasites in this way.
The Spider’s appetite for Locusts shows that
she must have more to do. Insects, unlike some human beings, eat only that
they may work. When I watch her, I find out what this work is. For nearly
another month, I see her adding layer upon layer to the walls of her nest.
These were at first semi-transparent; they become thick and opaque. This is
why the Spider eats, so that she may fill her silk-glands and make a
thick wrapper for her nest.
About the middle of September the little
Spiders come out of their eggs, but they do not leave their house, where they
are to spend the winter packed in soft wadding. The mother continues to watch
and spin, but she grows less active from day to day. She eats fewer Locusts;
she sometimes scorns those whom I myself entangle in her trap. But for
four or five months longer she keeps on making her inspection-rounds of
her egg-casket, happy at hearing the new-born Spiders swarming inside. At
last, when October ends, she clutches her children’s nursery and dies. She
has done all that a mother’s devotion can do; the special Providence that
watches over tiny animals will do the rest. When spring comes, the youngsters
will come out of their snug homes and scatter all over the neighborhood on
their floating threads, like the little Crab-spiders you have read
about.
[Illustration]
CHAPTER XXIV
THE BUILDING
OF A SPIDER’S WEB
The smallest garden contains the Garden Spiders,
all clever weavers.
Let us go every evening, step by step, from one
border of tall rosemaries to the next. Should things move too slowly, we will
sit down at the foot of the shrubs, where the light falls favorably, and
watch with unwearying attention. Let us give ourselves a title, “Inspector
of Spiders’ Webs!” There are not many people in that profession, and
we shan’t make any money by it; but never mind, we shall learn some
very interesting things.
The Spiders I watch are young ones, much
slenderer than they will be in the late autumn. They work by day, work even
in the sun, whereas the old ones weave only at night. Work starts in July, a
couple of hours before sunset.
The spinstresses of my inclosures then
leave their daytime hiding-places, choose their posts and begin to spin, one
here, another there. There are many of them; we can choose where we please.
Let us stop in front of this one, whom we surprise in the act of laying
the foundations of her web. She runs about the rosemary hedge, from the
tip of one branch to another, within the limits of some eighteen
inches. Gradually, she puts a thread in position, drawing it from her body
with the combs attached to her hind-legs. She comes and goes
impetuously, as though at random; she goes up, comes down, goes up again,
dives down again and each time strengthens the points of contact
with threads distributed here and there. The result is a sort of frame.
The shapeless structure is what she wishes; it marks out a flat, free,
and perpendicular space. This is all that is necessary.
A special
thread, the foundation of the stronger net which will be built later, is
stretched across the area of the other. It can be told from the others by its
isolation, its position at a distance from any twig that might interfere with
its swaying length. It never fails to have, in the middle, a thick white
point, formed of a little silk cushion.
The time has come to weave the
hunting-snare. The Spider starts from the center, which bears the white
signpost, and, running along the cross-thread, hurriedly reaches the
circumference, that is to say, the irregular frame inclosing the free space.
Still with the same sudden movement, she rushes from the outside to the
center; she starts again backwards and forwards, makes for the right, the
left, the top, the bottom; she hoists herself up, dives down, climbs up
again, runs down and always returns to the central landmark by roads that
slant in the most unexpected manner. Each time a radius or spoke is laid,
here, there, or elsewhere, in what looks like mad
disorder.
[Illustration]
Any one looking at the finished web, so
neat and regular in appearance, would think that the Spider laid the spokes
in an orderly fashion, one after the other. She does nothing of the sort, but
she knows what she is about, all the same. After setting a few spokes in one
direction, the Spider runs across to the other side to draw some in the
opposite direction. These sudden changes have a reason; they show us how
clever the Spider is in her business. If she began by laying all the spokes
on one side, she would pull the web out of shape or even destroy it.
She must put some on the other side to balance. She is a past mistress
of the secrets of rope-building, without serving an
apprenticeship.
One would think that this interrupted and apparently
disordered labor must result in a confused piece of work. Wrong: the rays
are equidistant and form a beautifully regular circle. Their number is
a characteristic mark of the different species. The Angular Epeira
places twenty-one in her web, the Banded Epeira thirty-two, the Silky
Epeira forty-two. These numbers are not absolutely fixed; but the variation
is very slight.
Now which of us would undertake, offhand, without much
preliminary experiment and without measuring-instruments, to divide a circle
into a given quantity of sectors or parts of equal width? The Garden
Spider, though weighted with a wallet and tottering on threads shaken by
the wind, performs the delicate division without stopping to think.
She achieves it by a method which seems mad according to our notions
of geometry. Out of disorder she brings order. We are amazed at the
result obtained. How does this Spider come to succeed with her
difficult problem, so strangely managed? I am still asking myself the
question.
The laying of the radii or spokes is finished. The Spider takes
her place in the center, on the little cushion. Stationed on this
support, she slowly turns round and round. She is engaged on a delicate piece
of work. With an extremely thin thread, she describes from spoke to
spoke, starting from the center, a spiral line with very close coils. This
is the center of the web. I will call it the “resting-floor.”
The
thread now becomes thicker. The first could hardly be seen; the second is
plainly visible. The Spider shifts her position with great slanting strides,
turns a few times, moving farther and farther from the center, fixes her line
each time to the spoke which she crosses, and at last comes to a stop at the
lower edge of the frame. She has described a spiral with coils of
rapidly-increasing width. The average distance between the coils, even in the
webs of the young Spiders, is about one third of an inch.
This spiral
is not a curved line. All curves are banished from the Spiders’ work; nothing
is used but the straight line and its combinations. This line forms the
cross-bars, or supporting rungs, connecting the spokes, or radii.
All
this is but a support for the snaring-web. Clinging on the one hand to the
radii, on the other to the cross-bars, the Spider covers the same ground as
when laying the first spiral, but in the opposite direction: formerly, she
moved away from the center; now she moves towards it and with closer and more
numerous circles. She starts from the end of the first spiral, near the
outside of the web.
What follows is hard to observe, for the movements
are very quick and jerky, consisting of a series of sudden little rushes,
sways, and bends that bewilder the eye. The two hind-legs, the weaving
implements, keep going constantly. One draws out the thread from the
spinneret, and passes it to the other, which lays it on the radius. As soon
as the radius is touched, the thread sticks to it by its own
glue.
[Illustration]
The Spider, without a stop of any kind, turns
and turns and turns, drawing nearer to the center and always fixing her
thread at each spoke which she crosses. At last, at some distance from the
center, on the edge of what I have called the resting-floor, the Spider
suddenly ends her spiral. She next eats the little cushion in the center,
which is a mat of ends of saved silk. She does this to economize silk, for
after she has eaten it the cushion will be turned into silk for the next
web she spins.
Two Spiders, the Banded and the Silky, sign their work
by laying a broad white ribbon in a thick zigzag from the center to the lower
edge of the web. Sometimes they put a second band of the same shape, but
a little shorter, opposite the first, on the upper part of the
web.
[Illustration]
THE STICKY SNARE
The spiral part of
the Garden Spider’s web is a wonderful contrivance. The thread that forms it
may be seen with the naked eye to be different from that of the framework and
the spokes. It glitters in the sun, and looks as though it were knotted. I
cannot examine it through the microscope outdoors because the web shakes so,
but by passing a sheet of glass under the web and lifting it I can take away
a few pieces of thread to study. The microscope now shows me an astounding
sight.
Those threads, so slender as to be almost invisible, are very
closely twisted twine, something like the gold cord of officers’
sword-knots. Moreover, they are hollow. They contain a sticky moisture
resembling a strong solution of gum arabic. I can see it trickling from the
broken ends. This moisture must ooze through the threads, making them
sticky. Indeed, they are sticky. When I lay a straw flat upon them, it
adheres at once. We see now that the Garden Spider hunts, not with springs,
but with sticky snares that catch everything, down to the
dandelion-plume that barely brushes against the web. Nevertheless, the Spider
herself is not caught in her own snare. Why?
For one thing, she spends
most of her time on her resting-floor in the middle of the web, which the
spiral does not enter. The resting-floor is not at all sticky, as I find when
I pass a straw against it. But sometimes when a victim is caught, perhaps
right at the end of the web, the Spider has to rush up quickly to bind it and
overcome its attempts to free itself. She seems to be able to walk upon her
network perfectly well then. Has she something on her feet which makes them
slip over the glue? Has she perhaps oiled them? Oil, you know, is the best
thing to prevent surfaces from sticking.
I pull out the leg of a live
Spider and put it to soak for an hour in disulphide of carbon, which
dissolves fat. I wash it carefully with a brush dipped in the same fluid.
When the washing is finished, the leg sticks to the spiral of the web! We see
now that the Spider varnishes herself with a special sweat so that she can go
on any part of her web without difficulty. However, she does not wish to
remain on the spiral too long, or the oil might wear away, so most of the
time she stays on her safe resting-floor.
This spiral thread of the
Spider’s is very quick to absorb moisture, as I find out by experiment. For
this reason the Garden Spiders, when they weave their webs in the early
morning, leave that part of the work unfinished, if the air turns misty. They
build the general framework, they lay the spokes, they make the
resting-floor, for all these parts are not affected by excess moisture; but
they are very careful not to work at the sticky spiral, which, if soaked by
the fog, would dissolve into sticky threads and lose its usefulness by being
wet. The net that was started will be finished to-morrow, if the weather is
right. But on hot days this property of the spiral is a fine thing; it does
not dry up, but absorbs all the moisture in the atmosphere and remains, at
the most scorching times of day, supple, elastic, and more and more
sticky. What bird-catcher could compete with the Garden Spider in the art
of laying snares? And all this industry and cunning for the capture of
a Moth!
Then, too, what a passion the Spider has for production. I
calculated that, in one sitting, each time that she remakes her web, the
Angular Spider produces some twenty yards of gummy thread. The more
skillful Silky Spider produces thirty. Well, during two months, the
Angular Spider, my neighbor, renewed her snare nearly every evening.
During that time she manufactured something like three quarters of a mile
of this tubular thread, rolled into a tight twist and bulging with
glue.
We cannot but wonder how she ever carries so much in her little
body, how she manages to twist her silk into this tube, how she fills it
with glue! And how does she first turn out plain threads, then russet
foam, for her nest, then black stripes to adorn the nest? I see the
results, but I cannot understand the working of her
factory.
[Illustration]
CHAPTER XXV
THE
GEOMETRY OF THE SPIDER’S WEB
[This chapter, one of the most wonderful in
Fabre’s books, is included in a simplified form in this volume, on account of
its interest to such younger readers as have studied
geometry.]
When we look at the webs of the Garden Spiders, especially
those of the Silky Spider and the Banded Spider, we notice first that the
spokes or radii are equally spaced; the angles formed by each consecutive
pair are of the same value; and this in spite of their number, which in
the webs of the Silky Spider sometimes exceeds forty. We know in what
a strange way the Spider weaves her web and divides the area of the
web into a large number of equal parts or sectors, a number which is
almost always the same in the work of each species of Spider. The
Spider darts here and there when laying her spokes as if she had no
plan, and this irresponsible way of working produces a beautiful web
like the rose-window in a church, a web which no designer could have
drawn better with compasses.
We shall also notice that, in each
sector, the various chords, parts of the angular spiral, are parallel to one
another and gradually draw closer together as they near the center. With the
two radiating lines that frame them they form obtuse angles on one side and
acute angles on the other; and these angles remain constant in the same
sector, because the chords are parallel.
There is more than this:
these same angles, the obtuse as well as the acute, do not alter in value,
from one sector to another, as far as the eye can judge. Taken as a whole,
therefore, the spiral consists of a series of cross-bars intersecting the
several radiating lines obliquely at angles of equal value.
By this
characteristic we recognize what geometricians have named the “logarithmic
spiral.” It is famous in science. The logarithmic spiral describes an endless
number of circuits around its pole, to which it constantly draws nearer
without ever being able to reach it. We could not see such a line, the whole
of it, even with our best philosophical instruments. It exists only in the
imagination of scientists. But the Spider knows it, and winds her spiral in
the same way, and very accurately at that.
Another property of this
spiral is that if one in imagination winds a flexible thread around it, then
unwinds the thread, keeping it taut the while, its free end will describe a
spiral similar at all points to the original. The curve will merely have
changed places. Jacques Bernouilli, the professor of mathematics who
discovered this magnificent theorem, had engraved on his tomb, as one of his
proudest titles to fame, the spiral and its double, made by the unwinding of
the thread. Written underneath it was the sentence: _Eadem mutata
resurgo._ “I rise again like unto myself.” It was a splendid flight of
fancy which showed his belief in immortality.
Now is this logarithmic
spiral, with its curious properties, merely an idea of the geometricians? Is
it a mere dream, an abstract riddle? |
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