THE LOCUSTS: THE LAST MOULT
I have just beheld a stirring sight: the last moult of a Locust, the
extraction of the adult from his larval wrapper. It is magnificent. The
object of my enthusiasm is the Grey Locust, the giant among our
Acridians, who is common on the vines at vintage-time, in September. On
account of his size—he is as long as my finger—he is a better subject
for observation than any other of his tribe.
The fat, ungraceful larva, a rough draft of the perfect insect, is
usually pale-green; but some also are bluish-green, dirty-yellow,
red-brown or even ashen-grey, like the grey of the adult. The corselet
is strongly keeled and notched, with a sprinkling of fine white
worm-holes. The hind-legs, powerful as those of mature age, have a
great haunch striped with red and a long shank shaped like a two-edged
saw.
The wing-cases, which in a few days will project well beyond the tip of
the abdomen, are in their present state two skimpy, triangular pinions,
touching back to back along their upper edges and continuing the keel
of the corselet. Their free ends stand up like a pointed gable. These
two coat-tails, of which the material seems to have been clipped short
with ridiculous meanness, just cover the creature’s nakedness at the
small of the back. They shelter two lean strips, the germs of the
wings, which are even more exiguous. In brief, the sumptuous, slender
sails of the near future are at present sheer rags, of such meagre
dimensions as to be grotesque. What will come out of these miserable
envelopes? A marvel of stately elegance.
Let us observe the proceedings in detail. Feeling itself ripe for
transformation, the creature clutches the trelliswork of the cage with
its hinder and intermediary legs. The fore-legs are folded and crossed
over the breast and are not employed in supporting the insect, which
hangs in a reversed position, back downwards. The triangular pinions,
the sheaths of the wing-cases, open their peaked roof and separate
sideways; the two narrow strips, the germs of the wings, stand in the
centre of the uncovered space and diverge slightly. The position for
the moult has now been taken with the necessary stability.
The first thing to be done is to burst the old tunic. Behind the
corselet, under the pointed roof of the prothorax, pulsations are
produced by alternate inflation and deflation. A similar operation is
performed in front of the neck and probably also under the entire
covering of the shell that is to be split. The delicacy of the
membranes at the joints enables us to perceive what is going on at
these bare points, but the harness of the corselet hides it from us in
the central portion.
It is there that the insect’s reserves of blood flow in waves. The
rising tide expresses itself in blows of an hydraulic battering-ram.
Distended by this rush of humours, by this injection wherein the
organism concentrates its energies, the skin at last splits along a
line of least resistance prepared by life’s subtle previsions. The
fissure yawns all along the corselet, opening precisely over the keel,
as though the two symmetrical halves had been soldered. Unbreakable any
elsewhere, the wrapper yields at this median point which is kept weaker
than the rest. The split is continued some little way back and runs
between the fastenings of the wings; it goes up the head as far as the
base of the antennæ, where it sends a short ramification to the right
and left.
Through this break the back is seen, quite soft, pale, hardly tinged
with grey. Slowly it swells into a larger and larger hunch. At last it
is wholly released. The head follows, extracted from its mask, which
remains in its place, intact in the smallest particular, but looking
strange with its great glassy eyes that do not see. The sheaths of the
antennæ, with not a wrinkle, with nothing out of order and with their
normal position unchanged, hang over this dead face, which is now
translucent.
Therefore, in emerging from their narrow sheaths, which enclosed them
with such absolute precision, the antennary threads encountered no
resistance capable of turning their scabbards inside out, or disturbing
their shape, or even wrinkling them. Without injuring the twisted
containers, the contents, equal in size and themselves twisted, have
managed to slip out as easily as a smooth, straight object would do, if
sliding in a loose sheath. The extraction-mechanism will be still more
remarkable in the case of the hind-legs.
Meanwhile it is the turn of the fore-legs and then of the intermediary
legs to shed armlets and gauntlets, always without the least rent,
however small, without a crease of rumpled material, without a trace of
any change in the natural position. The insect is now fixed to the top
of the cage only by the claws of the long hind-legs. It hangs
perpendicularly, head downwards, swinging like a pendulum, if I touch
the wire-gauze. Four tiny hooks are what it hangs by. If they gave way,
if they became unfastened, the insect would be lost, for it is
incapable of unfurling its enormous wings anywhere except in space. But
they will hold: life, before withdrawing from them, left them stiff and
solid, so as to be able firmly to support the struggles that are to
follow.
The wing-cases and wings now emerge. These are four narrow strips,
faintly grooved and looking like bits of paper ribbon. At this stage,
they are scarcely a quarter of their final length. So limp are they
that they bend under their own weight and sprawl along the insect’s
sides in the opposite direction to the normal. Their free end, which
should be turned backwards, now points towards the head of the Locust,
who is hanging upside down. Imagine four blades of thick grass, bent
and battered by a rainstorm, and you will have a fair picture of the
pitiable bunch formed by the future organs of flight.
It must be no light task to bring things to the requisite stage of
perfection. The deeper-seated changes are already well-started,
solidifying liquid mucilages, bringing order out of chaos; but so far
nothing outside betrays what is happening in that mysterious laboratory
where everything seems lifeless.
Meanwhile, the hind-legs become released. The great thighs appear in
view, tinted on their inner surface with a pale pink, which will soon
turn into a streak of bright crimson. The emergence is easy, the bulky
haunch clearing the way for the tapering knuckle.
It is different with the shank. This, in the adult insect, bristles
throughout its length with a double row of hard, pointed spikes.
Moreover, the lower extremity ends in four large spurs. It is a genuine
saw, but with two parallel sets of teeth and so powerful that, if we
dismiss the size from our minds, it might be compared with the rough
saw wielded by a quarryman.
The larva’s shin is similarly constructed, so that the object to be
extracted is contained in a sheath as awkwardly shaped as itself. Each
spur is enclosed in a similar spur, each tooth fits into the hollow of
a similar tooth; and the moulding is so exact that we should obtain no
more intimate contact if, instead of the envelope waiting to be shed,
we coated the limb with a layer of varnish distributed uniformly with a
fine brush.
Nevertheless the sawlike tibia slips out of its long, narrow case
without catching in it at any point whatever. If I had not seen this
happen over and over again, I could never have believed it: the
discarded legging is quite intact all the way down. Neither the
terminal spurs nor the two rows of spikes have caught in the delicate
mould. The saw has respected the dainty scabbard which a puff of my
breath is enough to tear; the formidable rake has slipped through
without leaving the least scratch behind it.
I was far from expecting such a result as this. Because of the spiked
armour, I imagined that the leg would strip in scales which came loose
of themselves or yielded to rubbing, like dead cuticle. How greatly did
the reality exceed my expectations!
From the spurs and spikes of the infinitely thin matrix there emerge
spurs and spikes that make the leg capable of cutting soft wood. This
is done without violence or the least inconvenience; and the discarded
garment remains where it is, hanging by the claws to the top of the
cage, uncreased and untorn. The magnifying-glass shows not a trace of
rough usage. As the thing was before the excoriation, so it remains
afterwards. The legging of dead skin continues, down to the pettiest
details, an exact replica of the live leg.
If any one suggested that we should extract a saw from some sort of
goldbeater’s-skin sheath which had been exactly moulded on the steel
and that we should perform the operation without producing the least
tear, we should burst out laughing: the thing is so flagrantly
impossible. Life makes light of these impossibilities; it has methods
of realizing the absurd, in case of need. And the Locust’s leg tells us
so.
If the saw of the shin were as hard as it is once it leaves its sheath,
it would absolutely refuse to come out without tearing to pieces the
tight-fitting scabbard. The difficulty therefore is evaded, for it is
essential that the leggings, which form the only suspension-cords,
should remain intact in order to furnish a firm support until the
deliverance is completed.
The leg in process of liberation is not a limb fit for walking; it has
not the rigidity which it will presently possess. It is soft and highly
flexible. In the portion which the progress of the moult exposes to
view, I see it bending and curving as I wish, under the mere influence
of its own weight, when I lift the cage. It is as supple as elastic
cord. And yet consolidation follows very rapidly, for the proper
stiffness will be acquired in a few minutes.
Farther on, in the part hidden from me by the sheath, the leg is
certainly softer and in a state of exquisite plasticity—I was almost
saying fluidity—which allows it to overcome difficult passages almost
as a liquid would flow.
The teeth of the saw are there, but have none of their future
sharpness. I am able to strip a leg partially with the point of a knife
and to extract the spines from their horny mould. They are germs of
spikes, flexible buds which bend under the slightest pressure and
resume their upright position as soon as the pressure is removed.
These spikes lie backwards when the leg is about to be drawn out; they
stand up again and solidify while it emerges. I am witnessing not the
mere stripping of gaiters from limbs completely enclosed, but rather a
sort of birth and growth which disconcert us by their rapidity.
Much in the same way, but with far less delicate precision, do the
claws of the Crayfish, at moulting-time, withdraw the soft flesh of
their two fingers from the old stony sheath.
The shanks are free at last. They are folded limply in the groove of
the thigh, there to mature without moving. The abdomen is next
stripped. Its fine tunic wrinkles, rumples and pushes back towards the
extremity, which alone for some time longer remains clad in the
moulting skin. Except at this point, the whole of the Locust is now
bare.
It is hanging perpendicularly, head down, supported by the claws of the
now empty leggings. Throughout this long and finikin work, the four
talons have never yielded, thanks to the delicacy and care with which
the extraction has been conducted.
The insect, fixed by the stern to its cast skin, does not move. Its
abdomen is immensely swollen, apparently distended by the reserve of
organizable humours which the expansion of the wings and wing-cases
will soon set in motion. The Locust is resting; he is recovering from
his exertions. Twenty minutes are spent in waiting.
Then, by an effort of its back, the hanging insect raises itself and
with its front tarsi grabs hold of the cast skin fastened above it.
Never did acrobat, swinging by his feet from the bar of a trapeze,
display greater strength of loin in lifting himself. When this feat is
accomplished, what remains to be done is nothing. With the support
which he has now gripped, the Locust climbs a little higher and reaches
the wire gauze of the cage. This takes the place of the brushwood which
the free insect would utilize for the transformation. He fixes himself
to it with his four front feet. Then the tip of the abdomen succeeds in
releasing itself, whereupon, loosened with one last shake, the empty
husk drops to the ground.
The fact of its falling interests me, for I remember the stubborn
persistency with which the Cicada’s cast skin defies the winter winds
without being detached from its supporting twig. The Locust’s
transfiguration is conducted in much the same way as the Cicada’s. Then
how is it that the Acridian gives himself such very shaky hangers? The
hooks hold so long as the work of tearing continues, though one would
think that this ought to bring down everything; they give way under a
trifling shock so soon as that work is done. We have, therefore, a very
unstable condition of equilibrium here, showing once more with what
delicate precision the insect leaves its sheath.
I said “tearing,” for want of a better word. But it is not quite that.
The term implies violence; and violence there cannot be any, because of
the unsteady balance. Should the Locust, upset by his exertions, come
to the ground, it would be all up with him. He would shrivel where he
lies; or, at any rate, his organs of flight, being unable to expand,
would remain pitiful shreds. The Locust does not tear himself loose; he
flows softly from his scabbard. It is as though he were forced out by a
gentle spring.
To return to the wings and wing-cases, which have made no apparent
progress since leaving the sheaths. They are still stumps, with fine
longitudinal seams, not much more than bits of rope. Their expansion,
which will take more than three hours, is reserved for the end, when
the insect is completely stripped and in its normal position.
We have seen the Locust turn head uppermost. This upright position is
enough to restore the natural arrangement of the wing-cases and wings.
Being extremely flexible and bent by their own weight, they were
hanging down with their loose end pointing towards the head of the
inverted insect. Now, still by virtue of their own weight, they are
straightened and put the right way up. They are no longer curved like
the petals of a flower, they are no longer in an inverted position; but
they still look miserably insignificant.
In its perfect state, the wing is fan-shaped. A radiating cluster of
strong nervures runs through it lengthwise and forms the framework of
the fan, which is readily furled or unfurled. The intervening spaces
are crossed by innumerable tiny bars which make of the whole a network
of rectangular meshes. The wing-case, which is coarser and much less
expanded, repeats this structure in squares.
In neither case does any of the mesh show during the rope’s-end stage.
All that we see is a few wrinkles, a few winding furrows, which tell us
that the stumps are bundles of cunningly folded material reduced to
their smallest volume.
The expansion begins near the shoulder. Where at first nothing definite
was to be distinguished, we soon see a diaphanous area subdivided into
meshes of exquisite precision. Little by little, with a slowness that
defies observation even through the magnifying-glass, this area
increases in extent at the expense of the shapeless terminal roll. My
eyes linger in vain on the confines of the two portions, the roll
developing and the gauze already developed: I see nothing, see no more
than I should see in a sheet of water. But wait a moment; and the
tissue of squares stands out with perfect clearness.
If we judged only by this first examination, we should really think
that an organizable fluid is abruptly congealing into a network of
nervures; we should imagine that we were in the presence of a
crystallization similar, in its suddenness, to that of a saline
solution on the slide of a microscope. Well, no: things cannot be
actually happening like that. Life does not perform its tasks so
hastily.
I detach a half-developed wing and turn the powerful eye of the
microscope upon it. This time I am satisfied. On the confines where the
network seemed to be gradually woven, that network was really in
existence. I can plainly see the longitudinal nervures, already thick
and strong; and I can also see, pale, it is true, and without relief,
the cross-bars. I find them all in the terminal roll, of which I
succeed in unfolding a few strips.
It is obvious. The wing is not at this moment a fabric on the loom,
through which the procreative energies are driving their shuttle; it is
a fabric already completed. All that it lacks to be perfect is
expansion and stiffness, even as our linen needs only starching and
ironing.
The flattening out is finished in three hours or more. The wings and
wing-cases stand up on the Locust’s back like a huge set of sails,
sometimes colourless, sometimes pale-green, as are the Cicada’s wings
at the beginning. We are amazed at their size when we think of the
paltry bundles that represented them at first. How did so much stuff
manage to find room there!
The fairy-tales tell us of a grain of hemp-seed that contained the
underlinen of a princess. Here is a grain that is even more
astonishing. The one in the story took years and years to sprout and
multiply and at last to yield the quantity of hemp required for the
trousseau; the Locust’s supplies a sumptuous set of sails in a short
space of time.
Slowly the proud crest, standing erect in four straight blades,
acquires consistency and colour. The latter turns the requisite shade
on the following day. For the first time the wings fold like a fan and
lie in their places; the wing-cases lower their outer edge and form a
gutter which falls over the sides. The transformation is finished. All
that remains for the big Locust to do is to harden his tissues still
further and to darken the grey of his costume while revelling in the
sun. Let us leave him to enjoy himself and retrace our steps a little.
The four stumps, which issued from their sheaths shortly after the
corselet split its keel down the middle, contain, as we have seen, the
wings and wing-cases, with their network of nervures. This network, if
not perfect, has at least the general plan of its numberless details
mapped out. To unfurl these poor bundles and convert them into generous
sails, it is enough that the organism, acting in this case like a
forcing-pump, should shoot a stream of humours, which have been kept in
reserve for this moment, the hardest of all, into the little channels
already prepared for their reception. With the channel marked out in
advance, a slight injection is sufficient to explain the rapid spread.
But what were the four strips of gauze while still contained in their
sheaths? Are the wings spatules and the three-cornered pinions of the
larva moulds whose creases, corners and sinuosities shape their
contents in their own image and weave the tissues of the future wing
and wing-case? If we had to do with a real instance of moulding, our
brains could call a halt. We should say to ourselves that it was quite
simple for the thing moulded to correspond with the shape of the mould.
But our halt would be short-lived, for the mould in its turn would want
explaining: we should have to seek for a solution of its infinite
intricacies. Let us not go so far back; we should be utterly in the
dark. Let us rather keep to facts that can be observed.
I examine through the magnifying-glass a pinion of a larva ripe for
transformation. I see a bundle of fairly thick nervures radiating
fanwise. Other nervures, paler and finer, are set in the intermediate
spaces. Lastly, the fabric is completed by a number of very short
transversal lines, more delicate still and chevron-shaped.
This, no doubt, gives a rough outline of the future wing-case; but how
different from the mature structure! The arrangement of the radiating
nervures, the skeleton of the edifice, is not at all the same; the
network formed by the transversal veins in no way suggests the
complicated pattern which we shall see later. The rudimentary is about
to be succeeded by the infinitely complex, the crude by the exquisitely
perfect. The same remark applies to the wing-spatule and its outcome,
the final wing.
It is quite evident, when we have the preparatory and the ultimate
stage before our eyes at the same time: the larva’s pinion is not
merely a mould which elaborates the material in its own image and
shapes the wing-case upon the model of its hollow. No, the membrane
which we are expecting is not yet inside in the form of a bundle which,
when unfurled, will astonish us with the size and the extreme
complexity of its texture. Or, to be accurate, it is there, but in a
potential state. Before becoming a real thing, it is a virtual thing,
which is nothing as yet, but which is capable of becoming something. It
is there just as much as the oak is inside its acorn.
A fine, transparent rim binds the free edge both of the embryo wing and
the embryo wing-case. Under a powerful lens we can see a few uncertain
outlines of the future lacework. This might well be the factory in
which life intends to set its materials going. There is nothing else
visible, nothing to suggest the prodigious network whose every mesh
will shortly have its form and place determined for it with geometrical
precision.
There must therefore be something better and greater than a mould to
make the organizable matter shape itself into a sheet of gauze and
describe the inextricable labyrinth of the nervation. There is a
primary plan, an ideal pattern which assigns to each atom its precise
place. Before the matter begins to move, the configuration is already
virtually traced, the courses of the plastic currents are already
marked out. The stones of our buildings are arranged in accordance with
the architect’s considered plan; they form an ideal assemblage before
existing as a real assemblage. Similarly, a Locust’s wing, that
sumptuous piece of lace emerging from a miserable sheath, speaks to us
of another Architect, the Author of the plans which life must follow in
its labours.
The genesis of living creatures offers to our contemplation, in an
infinity of ways, marvels far greater than those of the Acridian; but
generally they pass unperceived, overshadowed as they are by the veil
of time. The lapse of years, with its slow mysteries, robs us of the
most astonishing spectacles, unless our minds be endowed with a
stubborn patience. Here, by exception, things take place with a
swiftness that arrests even a wavering attention.
He who would, without wearisome delays, catch a glimpse of the
inconceivable dexterity with which life does its work has but to go to
the great Locust of the vines. The insect will show him that which,
with their extreme slowness, the sprouting seed, the budding leaf and
the blossoming flower hide from our curiosity. We cannot see a blade of
grass grow; but we can easily witness the growth of a Locust’s wings
and wing-cases.
We stand astounded at this sublime phantasmagoria of a grain of
hemp-seed which in a few hours becomes a superb piece of linen. What a
proud artist is life, driving its shuttle to weave the wings of a
Locust, one of those insignificant insects of which Pliny, long ago
said:
“In his tam parvis, fere nullis, quæ vis, quæ sapientia, quam
inextricabilis perfectis!”
How well the old naturalist was inspired on this occasion! Let us
repeat after him:
“What power, what wisdom, what indescribable perfection in the tiny
corner of life which the Locust of the vines has shown us!”
I have heard that a learned enquirer, to whom life was but a conflict
of physical and chemical forces, did not despair of one day obtaining
artificial organizable matter: protoplasm, as the official jargon has
it. Were it in my power, I should hasten to satisfy this ambitious
person.
Very well, be it so: you have thoroughly prepared your protoplasm. By
dint of long hours of meditation, deep study, scrupulous care and
inexhaustible patience, your wishes have been fulfilled; you have
extracted from your apparatus an albuminous glair, which goes bad
easily and stinks like the very devil in a few days’ time: in short,
filth. What do you propose to do with your product?
Will you organize it? Will you give it the structure of a living
edifice? Will you take a hypodermic syringe and inject it between two
impalpable films to obtain were it only the wing of a Gnat?
For that is more or less what the Locust does. He injects his
protoplasm between the two scales of the pinion; and the material
becomes a wing-case, because it finds as a guide the ideal archetype of
which I spoke just now. It is controlled in its intricate windings by a
plan which existed before the injection, before the material itself.
Have you this archetype, this coordinator of forms, this primordial
regulator, at the end of your syringe? No? Then throw away your
product! No life will ever spring from that chemical ordure.