|
To sum up, although, on the whole, the tactics of the exodus
remain much
the same, the two spinstresses of my region best-versed in the
art of
weaving mothers' wallets failed to come up to my expectations. I went
to
the trouble of rearing them, with disappointing results. Where shall
I
find again the wonderful spectacle which the Cross Spider offered me
by
chance? I shall find it--in an even more striking fashion--among
humbler
Spiders, whom I had neglected to observe.
CHAPTER
VIII: THE CRAB SPIDER
The Spider that showed me the exodus in all its
magnificence is known
officially as _Thomisus onustus_, WALCK. Though the
name suggest nothing
to the reader's mind, it has the advantage, at any rate,
of hurting
neither the throat nor the ear, as is too often the case with
scientific
nomenclature, which sounds more like sneezing than articulate
speech.
Since it is the rule to dignify plants and animals with a Latin
label,
let us at least respect the euphony of the classics and refrain
from
harsh splutters which spit out a name instead of pronouncing
it.
What will posterity do in face of the rising tide of a
barbarous
vocabulary which, under the pretence of progress, stifles real
knowledge?
It will relegate the whole business to the quagmire of
oblivion. But
what will never disappear is the popular name, which sounds
well, is
picturesque and conveys some sort of information. Such is the term
Crab
Spider, applied by the ancients to the group to which the
Thomisus
belongs, a pretty accurate term, for, in this case, there is an
evident
analogy between the Spider and the Crustacean.
Like the Crab,
the Thomisus walks sideways; she also has forelegs
stronger than her
hind-legs. The only thing wanting to complete the
resemblance is the front
pair of stone gauntlets, raised in the attitude
of self-defence.
The
Spider with the Crab-like figure does not know how to manufacture
nets for
catching game. Without springs or snares, she lies in ambush,
among the
flowers, and awaits the arrival of the quarry, which she kills
by
administering a scientific stab in the neck. The Thomisus, in
particular,
the subject of this chapter, is passionately addicted to the
pursuit of the
Domestic Bee. I have described the contests between the
victim and her
executioner, at greater length, elsewhere.
The Bee appears, seeking no
quarrel, intent upon plunder. She tests the
flowers with her tongue; she
selects 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
Thomisus, that bandit lurking
under cover of the flowers, issues from 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 paralysing, because the cervical
nerve-
centres are affected. The poor thing's legs stiffen; and all is over
in
a second. The murderess now sucks the victim's blood at her ease
and,
when she has done, scornfully flings the drained corpse aside. She
hides
herself once more, ready to bleed a second gleaner should the
occasion
offer.
This slaughter of the Bee engaged in the hallowed
delights of labour has
always revolted me. Why should there be workers to
feed idlers, why
sweated to keep sweaters in luxury? Why should so many
admirable lives
be sacrificed to the greater prosperity of brigandage? These
hateful
discords amid the general harmony perplex the thinker, all the more
as 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 the stomach, we are all of us, beasts and
men alike, ogres.
The dignity of labour, the joy of life, maternal affection,
the terrors
of death: all these do not count, in others; the main point is
that
morsel the be tender and savoury.
According to the etymology of
her name--[Greek text], a cord--the
Thomisus should be like the ancient
lictor, who bound the sufferer to the
stake. The comparison is not
inappropriate as regards many Spiders who
tie their prey with a thread to
subdue it and consume it at their ease;
but it just happens that the Thomisus
is at variance with her label. She
does not fasten her Bee, who, dying
suddenly of a bite in the neck,
offers no resistance to her
consumer. Carried away by his recollection
of the regular tactics, our
Spider's godfather overlooked the exception;
he did not know of the
perfidious mode of attack which renders the use of
a bow-string
superfluous.
Nor is the second name of _onustus_--loaded, burdened,
freighted--any too
happily chosen. The fact that the Bee-huntress carries a
heavy paunch is
no reason to refer to this as a distinctive
characteristic. Nearly all
Spiders have a voluminous belly, a silk-warehouse
where, in some cases,
the rigging of the net, in others, the swan's-down of
the nest is
manufactured. The Thomisus, a first-class nest-builder, does
like the
rest: she hoards in her abdomen, but without undue display of
obesity,
the wherewithal to house her family snugly.
Can the
expression _onustus_ refer simply to her slow and sidelong walk?
The
explanation appeals to me, without satisfying me fully. Except in
the case
of a sudden alarm, every Spider maintains a sober gait and a
wary pace. When
all is said, the scientific term is composed of a
misconception and a
worthless epithet. How difficult it is to name
animals rationally! Let us
be indulgent to the nomenclator: the
dictionary is becoming exhausted and the
constant flood that requires
cataloguing mounts incessantly, wearing out our
combinations of
syllables.
As the technical name tells the reader
nothing, how shall he be informed?
I see but one means, which is to invite
him to the May festivals, in the
waste-lands of the South. The murderess of
the Bees is of a chilly
constitution; in our parts, she hardly ever moves
away from the olive-
districts. Her favourite shrub is the white-leaved
rock-rose (_Cistus
albidus_), with the large, pink, crumpled, ephemeral
blooms that last but
a morning and are replaced, next day, by fresh flowers,
which have
blossomed in the cool dawn. This glorious efflorescence goes on
for five
or six weeks.
Here, the Bees plunder enthusiastically,
fussing and bustling in the
spacious whorl of the stamens, which beflour them
with yellow. Their
persecutrix knows of this affluence. She posts herself
in her
watch-house, under the rosy screen of a petal. Cast your eyes over
the
flower, more or less everywhere. If you see a Bee lying lifeless,
with
legs and tongue out-stretched, draw nearer: the Thomisus will be
there,
nine times out of ten. The thug has struck her blow; she is draining
the
blood of the departed.
After all, this cutter of Bees' throats is
a pretty, a very pretty
creature, despite her unwieldy paunch 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
back with
carmine arabesques. A narrow pale-green ribbon sometimes edges the
right
and left of the breast. It is not so rich as the costume of the
Banded
Epeira, but much more elegant because of its soberness, its
daintiness
and the artful blending of its hues. Novice fingers, which shrink
from
touching any other Spider, allow themselves to be enticed by
these
attractions; they do not fear to handle the beauteous Thomisus, so
gentle
in appearance.
Well, what can this gem among Spiders do? In
the first place, she makes
a nest worthy of its architect. With twigs and
horse-hair and bits of
wool, the Goldfinch, the Chaffinch and other masters
of the builder's art
construct an aerial bower in the fork of the
branches. Herself a lover
of high places, the Thomisus selects as the site
of her nest one of the
upper twigs of the rock-rose, her regular
hunting-ground, a twig withered
by the heat and possessing a few dead leaves,
which curl into a little
cottage. This is where she settles with a view to
her eggs.
Ascending and descending with a gentle swing in more or less
every
direction, the living shuttle, swollen with silk, weaves a bag
whose
outer casing becomes one with the dry leaves around. The work, which
is
partly visible and partly hidden by its supports, is a pure
dead-white.
Its shape, moulded in the angular interval between the bent
leaves, is
that of a cone and reminds us, on a smaller scale, of the nest of
the
Silky Epeira.
When the eggs are laid, the mouth of the receptacle
is hermetically
closed with a lid of the same white silk. Lastly, a few
threads,
stretched like a thin curtain, form a canopy above the nest and,
with the
curved tips of the leaves, frame a sort of alcove wherein the
mother
takes up her abode.
It is more than a place of rest after the
fatigues of her confinement: it
is a guard-room, an inspection-post where the
mother remains sprawling
until the youngsters' exodus. Greatly emaciated by
the laying of her
eggs and by her expenditure of silk, she lives only for the
protection of
her nest.
Should some vagrant pass near by, she hurries
from her watch-tower, lifts
a limb and puts the intruder to flight. If I
tease her with a straw, she
parries with big gestures, like those of a
prize-fighter. She uses her
fists against my weapon. When I propose to
dislodge her in view of
certain experiments, I find some difficulty in doing
so. She clings to
the silken floor, she frustrates my attacks, which I am
bound to moderate
lest I should injure her. She is no sooner attracted
outside than she
stubbornly returns to her post. She declines to leave her
treasure.
Even so does the Narbonne Lycosa struggle when we try to take
away her
pill. Each displays the same pluck and the same devotion; and also
the
same denseness in distinguishing her property from that of
others. The
Lycosa accepts without hesitation any strange pill which she is,
given in
exchange for her own; she confuses alien produce with the produce of
her
ovaries and her silk-factory. Those hallowed words, maternal love,
were
out of place here: it is an impetuous, an almost mechanical
impulse,
wherein real affection plays no part whatever. The beautiful Spider
of
the rock-roses is no more generously endowed. When moved from her
nest
to another of the same kind, she settles upon it and never stirs from
it,
even though the different arrangement of the leafy fence be such as
to
warn her that she is not really at home. Provided that she have
satin
under her feet, she does not notice her mistake; she watches
over
another's nest with the same vigilance which she might show in
watching
over her own.
The Lycosa surpasses her in maternal
blindness. She fastens to her
spinnerets and dangles, by way of a bag of
eggs, a ball of cork polished
with my file, a paper pellet, a little ball of
thread. In order to
discover if the Thomisus is capable of a similar error,
I gathered some
broken pieces of silk-worm's cocoon into a closed cone,
turning the
fragments so as to bring the smoother and more delicate inner
surface
outside. My attempt was unsuccessful. When removed from her home
and
placed on the artificial wallet, the mother Thomisus obstinately
refused
to settle there. Can she be more clear-sighted than the
Lycosa? Perhaps
so. Let us not be too extravagant with our praise, however;
the
imitation of the bag was a very clumsy one.
The work of laying is
finished by the end of May, after which, lying flat
on the ceiling of her
nest, the mother never leaves her guard-room,
either by night or day. Seeing
her look so thin and wrinkled, I imagine
that I can please her by bringing
her a provision of Bees, as I was wont
to do. I have misjudged her
needs. The Bee, hitherto her favourite
dish, tempts her no longer. In vain
does the prey buzz close by, an easy
capture within the cage: the watcher
does not shift from her post, takes
no notice of the windfall. She lives
exclusively upon maternal devotion,
a commendable but unsubstantial
fare. And so I see her pining away from
day to day, becoming more and more
wrinkled. 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 Epeira's little ones issue 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 unaided. The balloon has
to
split automatically and to scatter the youngsters and their
flossy
mattress all mixed up together. The Thomisus' 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 shrivelled relic.
When July
comes, the little ones emerge. In view of 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 spacious
lounge of criss-cross
threads. Here they remain, pretty quietly, for a
day or two; then
foot-bridges begin to be flung from one object to the
next. This is the
opportune moment.
I put the bunch laden with beasties on a small table,
in the shade,
before the open window. Soon, the exodus commences, but slowly
and
unsteadily. There are hesitations, retrogressions, perpendicular
falls
at the end of a thread, ascents that bring the hanging Spider up
again.
In short much ado 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,
the scene assumes a very different aspect.
The emigrants run to the top of
the twigs, bustle about actively. It
becomes a bewildering rope-yard, where
thousands of legs are drawing the
hemp from the spinnerets. I do not see the
ropes manufactured and sent
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 in
directions independent of her neighbours'. All are moving upwards,
all
are climbing some support, as can be perceived by the nimble motion
of
their legs. Moreover, the road is visible behind the climber, it is
of
double thickness, thanks to an added thread. 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.
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 microscopic projectiles
and mount in a spreading cluster. In
the end, it is like the bouquet at
the finish of a pyrotechnic display, the
sheaf of rockets fired
simultaneously. 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 firework. What a glorious
send-
off! What an entrance into the world! Clutching its aeronautic
thread,
the minute creature mounts in an apotheosis.
Sooner or later,
nearer or farther, the fall comes. To live, we have to
descend, often very
low, alas! The Crested Lark crumbles the
mule-droppings in the road and thus
picks up his food, the oaten grain
which he would never find by soaring in
the sky, his throat swollen with
song. We have to descend; the stomach's
inexorable claims demand it. The
Spiderling, therefore, touches
land. Gravity, tempered by the parachute,
is kind to her.
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.
CHAPTER IX: THE GARDEN SPIDERS: BUILDING THE
WEB
The fowling-snare is one of man's ingenious villainies. With
lines, pegs
and poles, two large, earth-coloured nets are stretched upon the
ground,
one to the right, the other to the left of a bare surface. A long
cord,
pulled, at the right moment, by the fowler, who hides in a brushwood
hut,
works them and brings them together suddenly, like a pair of
shutters.
Divided between the two nets are the cages of the
decoy-birds--Linnets
and Chaffinches, Greenfinches and Yellowhammers,
Buntings and
Ortolans--sharp-eared creatures which, on perceiving the distant
passage
of a flock of their own kind, forthwith utter a short calling
note. One
of them, the _Sambe_, an irresistible tempter, hops about and
flaps his
wings in apparent freedom. A bit of twine fastens him to his
convict's
stake. When, worn with fatigue and driven desperate by his vain
attempts
to get away, the sufferer lies down flat and refuses to do his duty,
the
fowler is able to stimulate him without stirring from his hut. A
long
string sets in motion a little lever working on a pivot. Raised from
the
ground by this diabolical contrivance, the bird flies, falls down
and
flies up again at each jerk of the cord.
The fowler waits, in the
mild sunlight of the autumn morning. Suddenly,
great excitement in the
cages. The Chaffinches chirp their
rallying-cry:
'Pinck! Pinck!'
There is something happening in the
sky. The _Sambe_, quick! They are
coming, the simpletons; they swoop down
upon the treacherous floor. With
a rapid movement, the man in ambush pulls
his string. The nets close and
the whole flock is caught.
Man has
wild beast's blood in his veins. The fowler hastens to the
slaughter. With
his thumb, he stifles the beating of the captives'
hearts, staves in their
skulls. The little birds, so many piteous heads
of game, will go to market,
strung in dozens on a wire passed through
their nostrils.
For
scoundrelly ingenuity the Epeira's net can bear comparison with the
fowler's;
it even surpasses it when, on patient study, the main features
of its supreme
perfection stand revealed. What refinement of art for a
mess of
Flies! Nowhere, in the whole animal kingdom, has the need to eat
inspired a
more cunning industry. If the reader will meditate upon the
description that
follows, he will certainly share my admiration.
First of all, we must
witness the making of the net; we must see it
constructed and see it again
and again, for the plan of such a complex
work can only be grasped in
fragments. To-day, observation will give us
one detail; to-morrow, it will
give us a second, suggesting fresh points
of view; as our visits multiply, a
new fact is each time added to the sum
total of the acquired data, confirming
those which come before or
directing our thoughts along unsuspected
paths.
The snow-ball rolling over the carpet of white grows enormous,
however
scanty each fresh layer be. Even so with truth in observational
science:
it is built up of trifles patiently gathered together. And, while
the
collecting of these trifles means that the student of Spider
industry
must not be chary of his time, at least it involves no distant
and
speculative research. The smallest garden contains Epeirae,
all
accomplished weavers.
In my enclosure, which I have stocked
carefully with the most famous
breeds, I have six different species under
observation, all of a useful
size, all first-class spinners. Their names are
the Banded Epeira
(_Epeira fasciata_, WALCK.), the Silky Epeira (_E.
sericea_, WALCK.), the
Angular Epeira (_E. angulata_, WALCK.), the
Pale-tinted Epeira (_E.
pallida_, OLIV.), the Diadem Epeira, or Cross Spider
(_E. diadema_,
CLERK.), and the Crater Epeira (_E. cratera_,
WALCK.).
I am able, at the proper hours, all through the fine season, to
question
them, to watch them at work, now this one, anon that, according to
the
chances of the day. What I did not see very plainly yesterday I can
see
the next day, under better conditions, and on any of the following
days,
until the phenomenon under observation is revealed in all
clearness.
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, opposite the rope-yard, where the light falls
favourably,
and watch with unwearying attention. Each trip will be good for
a fact
that fills some gap in the ideas already gathered. To appoint
one's
self, in this way, an inspector of Spiders' webs, for many years
in
succession and for long seasons, means joining a not
overcrowded
profession, I admit. Heaven knows, it does not enable one to put
money
by! No matter: the meditative mind returns from that school
fully
satisfied.
To describe the separate progress of the work in the
case of each of the
six Epeirae mentioned would be a useless repetition: all
six employ the
same methods and weave similar webs, save for certain details
that shall
be set forth later. I will, therefore, sum up in the aggregate
the
particulars supplied by one or other of them.
My subjects, in the
first instance, are young and boast but a slight
corporation, very far
removed from what it will be in the late autumn.
The belly, the wallet
containing the rope-works, hardly exceeds a
peppercorn in bulk. This
slenderness on the part of the spinstresses
must not prejudice us against
their work: there is no parity between
their skill and their years. The
adult Spiders, with their disgraceful
paunches, can do no
better.
Moreover, the beginners have one very precious advantage for
the
observer: they work by day, work even in the sun, whereas the old
ones
weave only at night, at unseasonable hours. The first show us
the
secrets of their looms without much difficulty; the others conceal
them
from us. Work starts in July, a couple of hours before
sunset.
The spinstresses of my enclosure then leave their daytime
hiding-places,
select 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 the
structure. Without any appreciable order, 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 wire-mill with the combs attached to her
hind-legs. This
preparatory work presents no appearance of a concerted
plan. The Spider
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 intricate moorings distributed here and there. The
result
is a scanty and disordered scaffolding.
Is disordered the
word? Perhaps not. The Epeira's eye, more experienced
in matters of this
sort than mine, has recognized the general lie of the
land; and the
rope-fabric has been erected accordingly: it is very
inaccurate in my
opinion, but very suitable for the Spider's designs.
What is it that she
really wants? A solid frame to contain the network
of the web. The
shapeless structure which she has just built fulfils the
desired conditions:
it marks out a flat, free and perpendicular area.
This is all that is
necessary.
The whole work, for that matter, is now soon completed; it is
done all
over again, each evening, from top to bottom, for the incidents of
the
chase destroy it in a night. The net is as yet too delicate to
resist
the desperate struggles of the captured prey. On the other hand,
the
adults' net, which is formed of stouter threads, is adapted to last
some
time; and the Epeira gives it a more carefully-constructed framework,
as
we shall see elsewhere.
A special thread, the foundation of the
real net, is stretched across the
area so capriciously circumscribed. It is
distinguished 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. This is
the beacon that marks the centre of the future edifice, the
post that
will guide the Epeira and bring order into the wilderness of twists
and
turns.
The time has come to weave the hunting-snare. The Spider
starts from the
centre, which bears the white signpost, and, running along
the
transversal thread, hurriedly reaches the circumference, that is to
say,
the irregular frame enclosing the free space. Still with the same
sudden
movement, she rushes from the circumference to the centre; 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.
The operation is so
erratically conducted that it takes the most
unremitting attention to follow
it at all. The Spider reaches the margin
of the area by one of the spokes
already placed. She goes along this
margin for some distance from the point
at which she landed, fixes her
thread to the frame and returns to the centre
by the same road which she
has just taken.
The thread obtained on the
way in a broken line, partly on the radius and
partly on the frame, is too
long for the exact distance between the
circumference and the central
point. On returning to this point, the
Spider adjusts her thread, stretches
it to the correct length, fixes it
and collects what remains on the central
signpost. In the case of each
radius laid, the surplus is treated in the
same fashion, so that the
signpost continues to increase in size. It was
first a speck; it is now
a little pellet, or even a small cushion of a
certain breadth.
We shall see presently what becomes of this cushion
whereon the Spider,
that niggardly housewife, lays her saved-up bits of
thread; for the
moment, we will note that the Epeira works it up with her
legs after
placing each spoke, teazles it with her claws, mats it into felt
with
noteworthy diligence. In so doing, she gives the spokes a solid
common
support, something like the hub of our carriage-wheels.
The
eventual regularity of the work suggests that the radii are spun in
the same
order in which they figure in the web, each following
immediately upon its
next neighbour. Matters pass in another manner,
which at first looks like
disorder, but which is really a judicious
contrivance. After setting a few
spokes in one direction, the Epeira
runs across to the other side to draw
some in the opposite direction.
These sudden changes of course are highly
logical; they show us how
proficient the Spider is in the mechanics of
rope-construction. Were
they to succeed one another regularly, the spokes of
one group, having
nothing as yet to counteract them, would distort the work
by their
straining, would even destroy it for lack of a stabler
support. Before
continuing, it is necessary to lay a converse group which
will maintain
the whole by its resistance. Any combination of forces acting
in one
direction must be forthwith neutralized by another in the
opposite
direction. This is what our statics teach us and what the Spider
puts
into practice; she is a past mistress of the secrets of
rope-building,
without serving an apprenticeship.
One would think that
this interrupted and apparently disordered labour
must result in a confused
piece of work. Wrong: the rays are equidistant
and form a
beautifully-regular orb. Their number is a characteristic
mark of the
different species. The Angular Epeira places 21 in her web,
the Banded
Epeira 32, the Silky Epeira 42. These numbers are not
absolutely fixed; but
the variation is very slight.
Now which of us would undertake, off-hand,
without much preliminary
experiment and without measuring-instruments, to
divide a circle into a
given quantity of sectors of equal width? The
Epeirae, though weighted
with a wallet and tottering on threads shaken by the
wind, effect the
delicate division without stopping to think. They achieve
it by a method
which seems mad according to our notions of geometry. Out of
disorder
they evolve order.
We must not, however, give them more than
their due. The angles are only
approximately equal; they satisfy the demands
of the eye, but cannot
stand the test of strict measurement. Mathematical
precision would be
superfluous here. No matter, we are amazed at the result
obtained. How
does the Epeira come to succeed with her difficult problem, so
strangely
managed? I am still asking myself the question.
The laying
of the radii is finished. The Spider takes her place in the
centre, on the
little cushion formed of the inaugural signpost and the
bits of thread left
over. 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 centre, a spiral line with
very close coils. The central space thus
worked attains, in the adults'
webs, the dimensions of the palm of one's
hand; in the younger Spiders' webs,
it is much smaller, but it is never
absent. For reasons which I will explain
in the course of this study, I
shall call it, in future, 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
centre, 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 structures of the young Epeirae, is
one
centimetre. {29}
Let us not be misled by the word 'spiral,' which
conveys the notion of a
curved line. All curves are banished from the
Spiders' work; nothing is
used but the straight line and its
combinations. All that is aimed at is
a polygonal line drawn in a curve as
geometry understands it. To this
polygonal line, a work destined to
disappear as the real toils are woven,
I will give the name of the 'auxiliary
spiral.' Its object is to supply
cross-bars, supporting rungs, especially in
the outer zone, where the
radii are too distant from one another to afford a
suitable groundwork.
Its object is also to guide the Epeira in the extremely
delicate business
which she is now about to undertake.
But, before
that, one last task becomes essential. The area occupied by
the spokes is
very irregular, being marked out by the supports of the
branch, which are
infinitely variable. There are angular niches which,
if skirted too closely,
would disturb the symmetry of the web about to be
constructed. The Epeira
needs an exact space wherein gradually to lay
her spiral thread. Moreover,
she must not leave any gaps through which
her prey might find an
outlet.
An expert in these matters, the Spider soon knows the corners
that have
to be filled up. With an alternating movement, first in this
direction,
then in that, she lays, upon the support of the radii, a thread
that
forms two acute angles at the lateral boundaries of the faulty part
and
describes a zigzag line not wholly unlike the ornament known as the
fret.
The sharp corners have now been filled with frets on every side;
the time
has come to work at the essential part, the snaring-web for which
all the
rest is but a support. Clinging on the one hand to the radii, on
the
other to the chords of the auxiliary spiral, the Epeira covers the
same
ground as when laying the spiral, but in the opposite
direction:
formerly, she moved away from the centre; now she moves towards it
and
with closer and more numerous circles. She starts from the base of
the
auxiliary spiral, near the frame.
What follows is difficult to
observe, for the movements are very quick
and spasmodic, consisting of a
series of sudden little rushes, sways and
bends that bewilder the eye. It
needs continuous attention and repeated
examination to distinguish the
progress of the work however slightly.
The two hind-legs, the weaving
implements, keep going constantly. Let us
name them according to their
position on the work-floor. I call the leg
that faces the centre of the
coil, when the animal moves, the 'inner
leg;' the one outside the coil the
'outer leg.'
The latter draws the thread from the spinneret and passes it
to the inner
leg, which, with a graceful movement, lays it on the radius
crossed. At
the same time, the first leg measures the distance; it grips the
last
coil placed in position and brings within a suitable range that point
of
the radius whereto the thread is to be fixed. As soon as the radius
is
touched, the thread sticks to it by its own glue. There are no
slow
operations, no knots: the fixing is done of itself.
Meanwhile,
turning by narrow degrees, the spinstress approaches the
auxiliary chords
that have just served as her support. When, in the end,
these chords become
too close, they will have to go; they would impair
the symmetry of the
work. The Spider, therefore, clutches and holds on
to the rungs of a higher
row; she picks up, one by one, as she goes
along, those which are of no more
use to her and gathers them into a fine-
spun ball at the contact-point of
the next spoke. Hence arises a series
of silky atoms marking the course of
the disappearing spiral.
The light has to fall favourably for us to
perceive these specks, the
only remains of the ruined auxiliary thread. One
would take them for
grains of dust, if the faultless regularity of their
distribution did not
remind us of the vanished spiral. They continue, still
visible, until
the final collapse of the net.
And the Spider, without
a stop of any kind, turns and turns and turns,
drawing nearer to the centre
and repeating the operation of fixing her
thread at each spoke which she
crosses. A good half-hour, an hour even
among the full-grown Spiders, is
spent on spiral circles, to the number
of about fifty for the web of the
Silky Epeira and thirty for those of
the Banded and the Angular
Epeira.
At last, at some distance from the centre, on the borders of what
I have
called the resting-floor, the Spider abruptly terminates her spiral
when
the space would still allow of a certain number of turns. We shall
see
the reason of this sudden stop presently. Next, the Epeira, no
matter
which, young or old, hurriedly flings herself upon the little
central
cushion, pulls it out and rolls it into a ball which I expected to
see
thrown away. But no: her thrifty nature does not permit this
waste. She
eats the cushion, at first an inaugural landmark, then a heap of
bits of
thread; she once more melts in the digestive crucible what is no
doubt
intended to be restored to the silken treasury. It is a tough
mouthful,
difficult for the stomach to elaborate; still, it is precious and
must
not be lost. The work finishes with the swallowing. Then and there,
the
Spider instals herself, head downwards, at her hunting-post in the
centre
of the web.
The operation which we have just seen gives rise to
a reflection. Men
are born right-handed. Thanks to a lack of symmetry that
has never been
explained, our right side is stronger and readier in its
movements than
our left. The inequality is especially noticeable in the two
hands. Our
language expresses this supremacy of the favoured side in the
terms
dexterity, adroitness and address, all of which allude to the right
hand.
Is the animal, on its side, right-handed, left-handed, or
unbiased? We
have had opportunities of showing that the Cricket, the
Grasshopper and
many others draw their bow, which is on the right wing-case,
over the
sounding apparatus, which is on the left wing-case. They
are
right-handed.
When you and I take an unpremeditated turn, we spin
round on our right
heel. The left side, the weaker, moves on the pivot of
the right, the
stronger. In the same way, nearly all the Molluscs that have
spiral
shells roll their coils from left to right. Among the numerous
species
in both land and water fauna, only a very few are exceptional and
turn
from right to left.
It would be interesting to try and work out
to what extent that part of
the zoological kingdom which boasts a two-sided
structure is divided into
right-handed and left-handed animals. Can
dissymetry, that source of
contrasts, be a general rule? Or are there
neutrals, endowed with equal
powers of skill and energy on both sides? Yes,
there are; and the Spider
is one of them. She enjoys the very enviable
privilege of possessing a
left side which is no less capable than the
right. She is ambidextrous,
as witness the following
observations.
When laying her snaring-thread, every Epeira turns in
either direction
indifferently, as a close watch will prove. Reasons whose
secret escapes
us determine the direction adopted. Once this or the other
course is
taken, the spinstress does not change it, even after incidents
that
sometimes occur to disturb the progress of the work. It may happen
that
a Gnat gets caught in the part already woven. The Spider
thereupon
abruptly interrupts her labours, hastens up to the prey, binds it
and
then returns to where she stopped and continues the spiral in the
same
order as before.
At the commencement of the work, gyration in one
direction being employed
as well as gyration in the other, we see that, when
making her repeated
webs, the same Epeira turns now her right side, now her
left to the
centre of the coil. Well, as we have said, it is always with the
inner
hind-leg, the leg nearer the centre, that is to say, in some cases
the
right and in some cases the left leg, that she places the thread
in
position, an exceedingly delicate operation calling for the display
of
exquisite skill, because of the quickness of the action and the need
for
preserving strictly equal distances. Any one seeing this leg
working
with such extreme precision, the right leg to-day, the left
to-morrow,
becomes convinced that the Epeira is highly
ambidextrous.
CHAPTER X: THE GARDEN SPIDERS: MY
NEIGHBOUR
Age does not modify the Epeira's talent in any essential
feature. As the
young worked, so do the old, the richer by a year's
experience. There
are no masters nor apprentices in their guild; all know
their craft from
the moment that the first thread is laid. We have learnt
something from
the novices: let us now look into the matter of their elders
and see what
additional task the needs of age impose upon them.
July
comes and gives me exactly what I wish for. While the new
inhabitants are
twisting their ropes on the rosemaries in the enclosure,
one evening, by the
last gleams of twilight, I discover a splendid
Spider, with a mighty belly,
just outside my door. This one is a matron;
she dates back to last year; her
majestic corpulence, so exceptional at
this season, proclaims the fact. I
know her for the Angular Epeira
(_Epeira angulata_, WALCK.), clad in grey and
girdled with two dark
stripes that meet in a point at the back. The base of
her abdomen swells
into a short nipple on either side.
This neighbour
will certainly serve my turn, provided that she do not
work too late at
night. Things bode well: I catch the buxom one in the
act of laying her
first threads. At this rate my success need not be won
at the expense of
sleep. And, in fact, I am able, throughout the month
of July and the greater
part of August, from eight to ten o'clock in the
evening, to watch the
construction of the web, which is more or less
ruined nightly by the
incidents of the chase and built up again, next
day, when too seriously
dilapidated.
During the two stifling months, when the light fails and a
spell of
coolness follows upon the furnace-heat of the day, it is easy for
me,
lantern in hand, to watch my neighbour's various operations. She
has
taken up her abode, at a convenient height for observation, between a
row
of cypress-trees and a clump of laurels, near the entrance to an
alley
haunted by Moths. The spot appears well-chosen, for the Epeira does
not
change it throughout the season, though she renews her net almost
every
night.
Punctually as darkness falls, our whole family goes and
calls upon her.
Big and little, we stand amazed at her wealth of belly and
her exuberant
somersaults in the maze of quivering ropes; we admire the
faultless
geometry of the net as it gradually takes shape. All agleam in
the
lantern-light, the work becomes a fairy orb, which seems woven
of
moonbeams.
Should I linger, in my anxiety to clear up certain
details, the
household, which by this time is in bed, waits for my return
before going
to sleep:
'What has she been doing this evening?' I am
asked. 'Has she finished
her web? Has she caught a Moth?'
I describe
what has happened. To-morrow, they will be in a less hurry to
go to bed:
they will want to see everything, to the very end. What
delightful, simple
evenings we have spent looking into the Spider's
workshop!
The journal
of the Angular Epeira, written up day by day, teaches us,
first of all, how
she obtains the ropes that form the framework of the
building. All day
invisible, crouching amid the cypress-leaves, the
Spider, at about eight
o'clock in the evening, solemnly emerges from her
retreat and makes for the
top of a branch. In this exalted position, she
sits for some time laying her
plans with due regard to the locality; she
consults the weather, ascertains
if the night will be fine. Then,
suddenly, with her eight legs wide-spread,
she lets herself drop straight
down, hanging to the line that issues from her
spinnerets. Just as the
rope-maker obtains the even output of his hemp by
walking backwards, so
does the Epeira obtain the discharge of hers by
falling. It is extracted
by the weight of her body.
The descent,
however, has not the brute speed which the force of gravity
would give it, if
uncontrolled. It is governed by the action of the
spinnerets, which contract
or expand their pores, or close them entirely,
at the faller's pleasure. And
so, with gentle moderation she pays out
this living plumb-line, of which my
lantern clearly shows me the plumb,
but not always the line. The great squab
seems at such times to be
sprawling in space, without the least
support.
She comes to an abrupt stop two inches from the ground; the
silk-reel
ceases working. The Spider turns round, clutches the line which
she has
just obtained and climbs up by this road, still spinning. But,
this
time, as she is no longer assisted by the force of gravity, the thread
is
extracted in another manner. The two hind-legs, with a quick
alternate
action, draw it from the wallet and let it go.
On returning
to her starting-point, at a height of six feet or more, the
Spider is now in
possession of a double line, bent into a loop and
floating loosely in a
current of air. She fixes her end where it suits
her and waits until the
other end, wafted by the wind, has fastened its
loop to the adjacent
twigs.
The desired result may be very slow in coming. It does not tire
the
unfailing patience of the Epeira, but it soon wears out mine. And it
has
happened to me sometimes to collaborate with the Spider. I pick up
the
floating loop with a straw and lay it on a branch, at a
convenient
height. The foot-bridge erected with my assistance is
considered
satisfactory, just as though the wind had placed it. I count
this
collaboration among the good actions standing to my
credit.
Feeling her thread fixed, the Epeira runs along it repeatedly,
from end
to end, adding a fibre to it on each journey. Whether I help or
not,
this forms the 'suspension-cable,' the main piece of the
framework. I
call it a cable, in spite of its extreme thinness, because of
its
structure. It looks as though it were single, but, at the two ends,
it
is seen to divide and spread, tuft-wise, into numerous constituent
parts,
which are the product of as many crossings. These diverging fibres,
with
their several contact-points, increase the steadiness of the
two
extremities.
The suspension-cable is incomparably stronger than
the rest of the work
and lasts for an indefinite time. The web is generally
shattered after
the night's hunting and is nearly always rewoven on the
following
evening. After the removal of the wreckage, it is made all over
again,
on the same site, cleared of everything except the cable from which
the
new network is to hang.
The laying of this cable is a somewhat
difficult matter, because the
success of the enterprise does not depend upon
the animal's industry
alone. It has to wait until a breeze carries the line
to the pier-head
in the bushes. Sometimes, a calm prevails; sometimes, the
thread catches
at an unsuitable point. This involves great expenditure of
time, with no
certainty of success. And so, when once the suspension-cable
is in
being, well and solidly placed, the Epeira does not change it, except
on critical occasions. Every evening, she passes and repasses over it,
strengthening it with fresh threads. |
|
댓글 없음:
댓글 쓰기