THE CAPRICORN
My youthful meditations owe some happy moments to Condillac's[1]
famous statue which, when endowed with the sense of smell, inhales the
scent of a rose and out of that single impression creates a whole
world of ideas. My twenty-year-old mind, full of faith in syllogisms,
loved to follow the deductive jugglery of the abbe-philosopher: I saw,
or seemed to see, the statue take life in that action of the nostrils,
acquiring attention, memory, judgment and all the psychological
paraphernalia, even as still waters are aroused and rippled by the
impact of a grain of sand. I recovered from my illusion under the
instruction of my abler master, the animal. The Capricorn shall teach
us that the problem is more obscure than the abbe led me to believe.
[Footnote 1: Etienne Bonnot de Condillac, Abbe de Mureaux (1715-1780),
the leading exponent of sensational philosophy. His most important
work is the _Traite des sensations_, in which he imagines a statue,
organized like a man, and endows it with the senses one by one,
beginning with that of smell. He argues by a process of imaginative
reconstruction that all human faculties and all human knowledge are
merely transformed sensation, to the exclusion of any other principle,
that, in short, everything has its source in sensation: man is nothing
but what he has acquired.--_Translator's Note_.]
When wedge and mallet are at work, preparing my provision of firewood
under the grey sky that heralds winter, a favourite relaxation creates
a welcome break in my daily output of prose. By my express orders, the
woodman has selected the oldest and most ravaged trunks in his stack.
My tastes bring a smile to his lips; he wonders by what whimsy I
prefer wood that is worm-eaten, _chirouna_, as he calls it, to sound
wood, which burns so much better. I have my views on the subject; and
the worthy man submits to them.
And now to us two, O my fine oak-trunk seamed with scars, gashed with
wounds whence trickle the brown drops smelling of the tan-yard. The
mallet drives home, the wedges bite, the wood splits. What do your
flanks contain? Real treasures for my studies. In the dry and hollow
parts, groups of various insects, capable of living through the bad
season of the year, have taken up their winter quarters: in the
low-roofed galleries, galleries built by some Buprestis Beetle,
Osmiae, working their paste of masticated leaves, have piled their
cells one above the other; in the deserted chambers and vestibules,
Megachiles have arranged their leafy jars; in the live wood, filled
with juicy saps, the larvae of the Capricorn (_Cerambyx miles_), the
chief author of the oak's undoing, have set up their home.
Strange creatures, of a verity, are these grubs, for an insect of
superior organization: bits of intestines crawling about! At this time
of year, the middle of autumn, I meet them of two different ages. The
older are almost as thick as one's finger; the others hardly attain
the diameter of a pencil. I find, in addition, pupae more or less
fully coloured, perfect insects, with a distended abdomen, ready to
leave the trunk when the hot weather comes again. Life inside the
wood, therefore, lasts three years. How is this long period of
solitude and captivity spent? In wandering lazily through the
thickness of the oak, in making roads whose rubbish serves as food.
The horse in Job swallows the ground[2] in a figure of speech; the
Capricorn's grub eats its way literally. With its carpenter's-gouge, a
strong black mandible, short, devoid of notches, scooped into a
sharp-edged spoon, it digs the opening of its tunnel. The piece cut
out is a mouthful which, as it enters the stomach, yields its scanty
juices and accumulates behind the worker in heaps of wormed wood. The
refuse leaves room in front by passing through the worker. A labour at
once of nutrition and of road-making, the path is devoured while
constructed; it is blocked behind as it makes way ahead. That,
however, is how all the borers who look to wood for victuals and
lodging set about their business.
[Footnote 2: "Chafing and raging, he swalloweth the ground, neither
doth he make account when the noise of the trumpet soundeth."--Job,
xxxix, 23 (Douai version).--_Translator's Note_.]
For the harsh work of its two gouges, or curved chisels, the larva of
the Capricorn concentrates its muscular strength in the front of its
body, which swells into a pestle-head. The Buprestis-grubs, those
other industrious carpenters, adopt a similar form; they even
exaggerate their pestle. The part that toils and carves hard wood
requires a robust structure; the rest of the body, which has but to
follow after, continues slim. The essential thing is that the
implement of the jaws should possess a solid support and a powerful
motor. The Cerambyx-larva strengthens its chisels with a stout, black,
horny armour that surrounds the mouth; yet, apart from its skull and
its equipment of tools, the grub has a skin as fine as satin and as
white as ivory. This dead white comes from a copious layer of grease
which the animal's spare diet would not lead us to suspect. True, it
has nothing to do, at every hour of the day and night, but gnaw. The
quantity of wood that passes into its stomach makes up for the dearth
of nourishing elements.
The legs, consisting of three pieces, the first globular, the last
sharp-pointed, are mere rudiments, vestiges. They are hardly a
millimetre[3] long. For this reason, they are of no use whatever for
walking; they do not even bear upon the supporting surface, being kept
off it by the obesity of the chest. The organs of locomotion are
something altogether different. The Cetonia-grub[4] has shown us how,
with the aid of the hairs and the pad-like excrescences upon its
spine, it manages to reverse the universally-accepted usage and to
wriggle along on its back. The grub of the Capricorn is even more
ingenious: it moves at the same time on its back and belly; instead of
the useless legs of the thorax, it has a walking-apparatus almost
resembling feet, which appear, contrary to every rule, on the dorsal
surface.
[Footnote 3: .039 inch.--_Translator's Note_.]
[Footnote 4: For the grub of the Cetonia, or Rose-chafer, cf. _The
Life and Love of the Insect_, by J. Henri Fabre, translated by
Alexander Teixeira de Mattos: chap. xi.--_Translator's Note_.]
The first seven segments of the abdomen have, both above and below, a
four-sided facet, bristling with rough protuberances. This the grub
can either expand or contract, making it stick out or lie flat at
will. The upper facets consist of two excrescences separated by the
mid-dorsal line; the lower ones have not this divided appearance.
These are the organs of locomotion, the ambulacra. When the larva
wishes to move forwards, it expands its hinder ambulacra, those on the
back as well as those on the belly, and contracts its front ones.
Fixed to the side of the narrow gallery by their ridges, the hind-pads
give the grub a purchase. The flattening of the fore-pads, by
decreasing the diameter, allows it to slip forward and to take half a
step. To complete the step, the hind-quarters have to be brought up
the same distance. With this object, the front pads fill out and
provide support, while those behind shrink and leave free scope for
their segments to contract.
With the double support of its back and belly, with alternate puffings
and shrinkings, the animal easily advances or retreats along its
gallery, a sort of mould which the contents fill without a gap. But,
if the locomotory pads grip only on one side, progress becomes
impossible. When placed on the smooth wood of my table, the animal
wriggles slowly; it lengthens and shortens without advancing by a
hair's-breadth. Laid on the surface of a piece of split oak, a rough,
uneven surface, due to the gash made by the wedge, it twists and
writhes, moves the front part of its body very slowly from left to
right and right to left, lifts it a little, lowers it and begins
again. These are the most extensive movements made. The vestigial legs
remain inert and absolutely useless.
Then why are they there? Better to lose them altogether, if it be true
that crawling inside the oak has deprived the animal of the good legs
with which it started. The influence of environment, so well-inspired
in endowing the grub with ambulatory pads, becomes a mockery when it
leaves it these ridiculous stumps. Can the structure, perchance, be
obeying other rules than those of environment?
Though the useless legs, the germs of the future limbs, persist, there
is no sign in the grub of the eyes wherewith the Cerambyx will be
richly gifted. The larva has not the least trace of organs of vision.
What would it do with sight, in the murky thickness of a tree-trunk?
Hearing is likewise absent. In the never-troubled silence of the oak's
inmost heart, the sense of hearing would be a non-sense. Where sounds
are lacking, of what use is the faculty of discerning them? Should
there be any doubts, I will reply to them with the following
experiment. Split lengthwise, the grub's abode leaves a half-tunnel
wherein I can watch the occupant's doings. When left alone, it now
gnaws the front of its gallery, now rests, fixed by its ambulacra to
the two sides of the channel. I avail myself of these moments of quiet
to enquire into its power of perceiving sounds. The banging of hard
bodies, the ring of metallic objects, the grating of a file upon a saw
are tried in vain. The animal remains impassive. Not a wince, not a
move of the skin; no sign of awakened attention. I succeed no better
when I scratch the wood close by with a hard point, to imitate the
sound of some neighbouring larva gnawing the intervening thickness.
The indifference to my noisy tricks could be no greater in a lifeless
object. The animal is deaf.
Can it smell? Everything tells us no. Scent is of assistance in the
search for food. But the Capricorn-grub need not go in quest of
eatables: it feeds on its home, it lives on the wood that gives it
shelter. Let us make an attempt or two, however. I scoop in a log of
fresh cypress-wood a groove of the same diameter as that of the
natural galleries and I place the worm inside it. Cypress-wood is
strongly-scented; it possesses in a high degree that resinous aroma
which characterizes most of the pine family. Well, when laid in the
odoriferous channel, the larva goes to the end, as far as it can go,
and makes no further movement. Does not this placid quiescence point
to the absence of a sense of smell? The resinous flavour, so strange
to the grub which has always lived in oak, ought to vex it, to trouble
it; and the disagreeable impression ought to be revealed by a certain
commotion, by certain attempts to get away. Well, nothing of the kind
happens: once the larva has found the right position in the groove, it
does not stir. I do more: I set before it, at a very short distance,
in its normal canal, a piece of camphor. Again, no effect. Camphor is
followed by naphthaline. Still nothing. After these fruitless
endeavours, I do not think that I am going too far when I deny the
creature a sense of smell.
Taste is there, no doubt. But such taste! The food is without variety:
oak, for three years at a stretch, and nothing else. What can the
grub's palate appreciate in this monotonous fare? The tannic relish of
a fresh piece, oozing with sap; the uninteresting flavour of an
over-dry piece, robbed of its natural condiment: these probably
represent the whole gustative scale.
There remains touch, the far-spreading passive sense common to all
live flesh that quivers under the goad of pain. The sensitive schedule
of the Cerambyx-grub, therefore, is limited to taste and touch, both
exceedingly obtuse. This almost brings us to Condillac's statue. The
imaginary being of the philosopher had one sense only, that of smell,
equal in delicacy to our own; the real being, the ravager of the oak,
has two, inferior, even when put together, to the former, which so
plainly perceived the scent of a rose and distinguished it so clearly
from any other. The real case will bear comparison with the
fictitious.
What can be the psychology of a creature possessing such a powerful
digestive organism combined with such a feeble set of senses? A vain
wish has often come to me in my dreams: it is to be able to think, for
a few minutes, with the crude brain of my Dog, to see the world with
the faceted eyes of a Gnat. How things would change in appearance!
They would change much more if interpreted by the intellect of the
grub. What have the lessons of touch and taste contributed to that
rudimentary receptacle of impressions? Very little; almost nothing.
The animal knows that the best bits possess an astringent flavour;
that the sides of a passage not carefully planed are painful to the
skin. This is the utmost limit of its acquired wisdom. In comparison,
the statue with the sensitive nostrils was a marvel of knowledge, a
paragon too generously endowed by its inventor. It remembered,
compared, judged, reasoned: does the drowsy, digesting paunch
remember? Does it compare? Does it reason? I defined the
Capricorn-grub as a bit of an intestine that crawls about. The
undeniable accuracy of this definition provides me with my answer: the
grub has the aggregate of sense-impressions that a bit of an intestine
may hope to have.
And this nothing-at-all is capable of marvellous acts of foresight;
this belly, which knows hardly anything of the present, sees very
clearly into the future. Let us take an illustration on this curious
subject. For three years on end, the larva wanders about in the thick
of the trunk; it goes up, goes down, turns to this side and that; it
leaves one vein for another of better flavour, but without moving too
far from the inner depths, where the temperature is milder and greater
safety reigns. A day is at hand, a dangerous day for the recluse
obliged to quit its excellent retreat and face the perils of the
surface. Eating is not everything: we have to get out of this. The
larva, so well-equipped with tools and muscular strength, finds no
difficulty in going where it pleases, by boring through the wood; but
does the coming Capricorn, whose short spell of life must be spent in
the open air, possess the same advantages? Hatched inside the trunk,
will the long-horned Beetle be able to clear itself a way of escape?
That is the difficulty which the worm solves by inspiration. Less
versed in things of the future, despite my gleams of reason, I resort
to experiment with a view to fathoming the question. I begin by
ascertaining that the Capricorn, when he wishes to leave the trunk, is
absolutely unable to make use of the tunnel wrought by the larva. It
is a very long and very irregular maze, blocked with great heaps of
wormed wood. Its diameter decreases progressively from the final blind
alley to the starting-point. The larva entered the timber as slim as a
tiny bit of straw; it is to-day as thick as one's finger. In its three
years' wanderings, it always dug its gallery according to the mould of
its body. Evidently, the road by which the larva entered and moved
about cannot be the Capricorn's exit-way: his immoderate antennae, his
long legs, his inflexible armour-plates would encounter an insuperable
obstacle in the narrow, winding corridor, which would have to be
cleared of its wormed wood and, moreover, greatly enlarged. It would
be less fatiguing to attack the untouched timber and dig straight
ahead. Is the insect capable of doing so? We shall see.
I make some chambers of suitable size in oak logs chopped in two; and
each of my artificial cells receives a newly-transformed Cerambyx,
such as my provisions of firewood supply, when split by the wedge, in
October. The two pieces are then joined and kept together with a few
bands of wire. June comes. I hear a scraping inside my billets. Will
the Capricorns come out, or not? The delivery does not seem difficult
to me: there is hardly three-quarters of an inch to pierce. Not one
emerges. When all is silence, I open my apparatus. The captives, from
first to last, are dead. A vestige of sawdust, less than a pinch of
snuff, represents all their work.
I expected more from those sturdy tools, their mandibles. But, as we
have seen before, the tool does not make the workman.[5] In spite of
their boring-implements, the hermits die in my cases for lack of
skill. I subject others to less arduous tests. I enclose them in
spacious reed-stumps, equal in diameter to the natal cell. The
obstacle to be pierced is the natural diaphragm, a yielding partition
two or three millimetres[6] thick. Some free themselves; others
cannot. The less valiant ones succumb, stopped by the frail barrier.
What would it be if they had to pass through a thickness of oak?
[Footnote 5: Cf. _The Life and Love of the Insect_: chap. iii. "The
tool does not make the workman. The insect exerts its gifts as a
specialist with any kind of tool wherewith it is supplied. It can saw
with a plane or plane with a saw, like the model workman of whom
Franklin tells us."--_Translator's Note_.]
[Footnote 6: .078 to .117 inch.--_Translator's Note_.]
We are now persuaded: despite his stalwart appearance, the Capricorn
is powerless to leave the tree-trunk by his unaided efforts. It
therefore falls to the worm, to the wisdom of that bit of an
intestine, to prepare the way for him. We see renewed, in another
form, the feats of prowess of the Anthrax, whose pupa, armed with
trepans, bores through rock on the feeble Fly's behalf. Urged by a
presentiment that to us remains an unfathomable mystery, the
Cerambyx-grub leaves the inside of the oak, its peaceful retreat, its
unassailable stronghold, to wriggle towards the outside, where lives
the foe, the Woodpecker, who may gobble up the succulent little
sausage. At the risk of its life, it stubbornly digs and gnaws to the
very bark, of which it leaves no more intact than the thinnest film, a
slender screen. Sometimes, even, the rash one opens the window wide.
This is the Capricorn's doorway. The insect will have but to file the
screen a little with its mandibles, to bump against it with its
forehead, in order to bring it down; it will even have nothing to do
when the window is free, as often happens. The unskilled carpenter,
burdened with his extravagant head-dress, will emerge from the
darkness through this opening when the summer heats arrive.
After the cares of the future come the cares of the present. The
larva, which has just opened the aperture of escape, retreats some
distance down its gallery and, in the side of the exit-way, digs
itself a transformation-chamber more sumptuously furnished and
barricaded than any that I have ever seen. It is a roomy niche, shaped
like a flattened ellipsoid, the length of which reaches some eighty to
a hundred millimetres.[7] The two axes of the cross-section vary: the
horizontal measures twenty-five to thirty millimetres;[8] the vertical
measures only fifteen.[9] This greater dimension of the cell, where
the thickness of the perfect insect is concerned, leaves a certain
scope for the action of its legs when the time comes for forcing the
barricade, which is more than a close-fitting mummy-case would do.
[Footnote 7: 3 to 4 inches.--_Translator's Note_.]
[Footnote 8: .975 to 1.17 inch.--_Translator's Note_.]
[Footnote 9: .585 inch.--_Translator's Note_.]
The barricade in question, a door which the larva builds to exclude
the dangers from without, is two- and even three-fold. Outside, it is
a stack of woody refuse, of particles of chopped timber; inside, a
mineral hatch, a concave cover, all in one piece, of a chalky white.
Pretty often, but not always, there is added to these two layers an
inner casing of shavings. Behind this compound door, the larva makes
its arrangements for the metamorphosis. The sides of the chamber are
rasped, thus providing a sort of down formed of ravelled woody fibres,
broken into minute shreds. The velvety matter, as and when obtained,
is applied to the wall in a continuous felt at least a millimetre
thick.[10] The chamber is thus padded throughout with a fine
swan's-down, a delicate precaution taken by the rough worm on behalf
of the tender pupa.
[Footnote 10: .039 inch.--_Translator's Note_.]
Let us hark back to the most curious part of the furnishing, the
mineral hatch or inner door of the entrance. It is an elliptical
skull-cap, white and hard as chalk, smooth within and knotted without,
resembling more or less closely an acorn-cup. The knots show that the
matter is supplied in small, pasty mouthfuls, solidifying outside in
slight projections which the animal does not remove, being unable to
get at them, and polished on the inside surface, which is within the
worm's reach. What can be the nature of that singular lid whereof the
Cerambyx furnishes me with the first specimen? It is as hard and
brittle as a flake of lime-stone. It can be dissolved cold in nitric
acid, discharging little gaseous bubbles. The process of solution is a
slow one, requiring several hours for a tiny fragment. Everything is
dissolved, except a few yellowish flocks, which appear to be of an
organic nature. As a matter of fact, a piece of the lid, when
subjected to heat, blackens, which proves the presence of an organic
glue cementing the mineral matter. The solution becomes muddy if
oxalate of ammonia be added and deposits a copious white precipitate.
These signs indicate calcium carbonate. I look for urate of ammonia,
that constantly-recurring product of the various stages of the
metamorphoses. It is not there: I find not the least trace of
murexide. The lid, therefore, is composed solely of carbonate of lime
and of an organic cement, no doubt of an albuminous character, which
gives consistency to the chalky paste.
Had circumstances served me better, I should have tried to discover in
which of the worm's organs the stony deposit dwells. I am, however,
convinced: it is the stomach, the chylific ventricle, that supplies
the chalk. It keeps it separate from the food, either as original
matter or as a derivative of the ammonium urate; it purges it of all
foreign bodies, when the larval period comes to an end, and holds it
in reserve until the time comes to disgorge it. This freestone-factory
causes me no astonishment: when the manufacturer undergoes his change,
it serves for various chemical works. Certain Oil-beetles, such as the
Sitaris, locate in it the urate of ammonia, the refuse of the
transformed organism; the Sphex, the Pelopaei, the Scoliae,[11] use it
to manufacture the shellac wherewith the silk of the cocoon is
varnished. Further investigations will only swell the aggregate of the
products of this obliging organ.
[Footnote 11: Three species of Digger-wasps.--_Translator's Note_.]
When the exit-way is prepared and the cell upholstered in velvet and
closed with a three-fold barricade, the industrious worm has concluded
its task. It lays aside its tools, sheds its skin and becomes a nymph,
a pupa, weakness personified, in swaddling-clothes, on a soft couch.
The head is always turned towards the door. This is a trifling detail
in appearance; but it is everything in reality. To lie this way or
that in the long cell is a matter of great indifference to the worm,
which is very supple, turning easily in its narrow lodging and
adopting whatever position it pleases. The coming Capricorn will not
enjoy the same privileges. Stiffly girt in his horn cuirass, he will
not be able to turn from end to end; he will not even be capable of
bending, if some sudden wind should make the passage difficult. He
must absolutely find the door in front of him, lest he perish in the
casket. Should the grub forget this little formality, should it lie
down to its nymphal sleep with its head at the back of the cell, the
Capricorn is infallibly lost: his cradle becomes a hopeless dungeon.
But there is no fear of this danger: the knowledge of the bit of an
intestine is too sound in things of the future for the grub to neglect
the formality of keeping its head to the door. At the end of spring,
the Capricorn, now in possession of his full strength, dreams of the
joys of the sun, of the festivals of light. He wants to get out. What
does he find before him? A heap of filings easily dispersed with his
claws; next, a stone lid which he need not even break into fragments:
it comes undone in one piece; it is removed from its frame with a few
pushes of the forehead, a few tugs of the claws. In fact, I find the
lid intact on the threshold of the abandoned cells. Last comes a
second mass of woody remnants as easy to disperse as the first. The
road is now free: the Cerambyx has but to follow the spacious
vestibule, which will lead him, without the possibility of mistake, to
the exit. Should the window not be open, all that he has to do is to
gnaw through a thin screen: an easy task; and behold him outside, his
long antennae aquiver with excitement.
What have we learnt from him? Nothing from him; much from his grub.
This grub, so poor in sensory organs, gives us with its prescience no
little food for reflection. It knows that the coming Beetle will not
be able to cut himself a road through the oak and it bethinks itself
of opening one for him at its own risk and peril. It knows that the
Cerambyx, in his stiff armour, will never be able to turn and make for
the orifice of the cell; and it takes care to fall into its nymphal
sleep with its head to the door. It knows how soft the pupa's flesh
will be and upholsters the bedroom with velvet. It knows that the
enemy is likely to break in during the slow work of the transformation
and, to set a bulwark against his attacks, it stores a calcium pap
inside its stomach. It knows the future with a clear vision, or, to be
accurate, behaves as though it knew the future. Whence did it derive
the motives of its actions? Certainly not from the experience of the
senses. What does it know of the outside world? Let us repeat, as much
as a bit of an intestine can know. And this sense-less creature
astounds us! I regret that the clever logician, instead of conceiving
a statue smelling a rose, did not imagine it gifted with some
instinct. How quickly he would have recognized that, quite apart from
sense-impressions, the animal, including man, possesses certain
psychological resources, certain inspirations that are innate and not
acquired!