A BARREN PROMISE
In the nymph of Onthophagus Taurus there rises, on the front edge of
the corselet, a single horn, as strong as the two others and shaped
like a cylinder ending in a conical knob. It points forward and is
fixed in the middle of the frontal crescent, projecting a little beyond
it. The arrangement is gloriously original. The carvers of
hieroglyphics would have beheld in it the crescent of Isis wherein dips
the edge of the world.
Other singularities complete the curious nymph. To right and left, the
stomach is armed, on either side, with four little horns resembling
crystal spikes. Total, eleven pieces on the harness: two on the
forehead; one on the thorax; eight on the abdomen. The beast of yore
delighted in queer horns: certain reptiles of the geological period
stuck a pointed spur on their upper eyelids. The Onthophagus, more
daring, sports eight on the sides of his belly, in addition to the
spear which he plants upon his back. The frontal horns may be excused:
they are pretty generally worn; but what does he propose to do with the
others? Nothing. They are passing fancies, jewels of early youth; the
adult insect will not retain the least trace of them.
The nymph matures. The appendages of the forehead, at first quite
crystalline, now show, transparently, a streak of reddish brown, curved
arc-wise. These are real horns taking shape, consistency and colour.
The appendage of the corselet and those of the belly, on the other
hand, preserve their glassy appearance. They are barren sacks, void of
any self-developing germ. The organism produced them in an impetuous
moment; now, scornful, or perhaps powerless, it allows the work to
wither and become useless.
When the nymph sheds its covering and the fine tunic of the adult form
is torn, these strange horns crumble into shreds, which fall away with
the rest of the cast clothing. In the hope of finding at least a trace
of the vanished things, the lens in vain explores the bases but lately
occupied. There is nothing appreciable left: smoothness takes the place
of protuberance; nullity succeeds to reality. Of the accessory panoply
that promised so much, absolutely naught remains: everything has
disappeared, evaporated, so to speak.
Onthophagus Taurus is not the only one endowed with those fleeting
appendages, which vanish wholly when the nymph sheds its clothes. The
other members of the tribe possess similar horny manifestations on
their bellies and corselets. These all disappear entirely in the
perfect insect.
A simple setting forth of the facts does not suffice us: we should like
to guess at the motive of this corniculate display. Is it a vague
memory of the customs of olden time, when life spent its excess of
young sap upon quaint creations, banished to-day from our
better-balanced world? Is the Onthophagus the dwarfed representative of
an old race of horned animals now extinct? Does it give us a faint
image of the past?
The surmise rests upon no valid foundation. The Dung-beetle is recent
in the general chronology of created beings; he ranks among the
last-comers. With him there is no means of going back to the mists of
the past, so favourable to the invention of imaginary precursors. The
geological layers and even the lacustrian layers, rich in Diptera and
Weevils, have so far furnished not the slightest relic of the
Dung-workers. This being so, it is wiser not to refer to distant horned
ancestors as accounting for their degenerate descendant, the
Onthophagus.
Since the past explains nothing, let us turn to the future. If the
thoracic horn be not a reminiscence, it may be a promise. It represents
a timid attempt, which the ages will harden into a permanent weapon. It
lets us assist at the slow and gradual evolution of a new organ; it
shows us life working on a portion of the adult’s corselet, which does
not yet exist, but which is to exist some day. We take the genesis of
the species in the act; the present teaches us how the future is
prepared.
And what does the insect that has conceived the ambition of later
planting a spear upon its chine propose to make of its projected work?
At least as an adjunct of masculine finery, the thing is in fashion
among various foreign Scarabs that feed themselves and their grubs on
vegetable matters in a state of decomposition. These giants among the
wing-cased tribe delight in associating their placid corpulence with
halberds terrible to gaze upon.
Look at this one—Dynastes Hercules his name—an inmate of the rotten
tree-stumps under the torrid West-Indian skies. The peaceable colossus
well deserves his name: he measures three inches long. Of what service
can the threatening rapier of the corselet and the toothed lifting-jack
of the forehead be to him, unless it be to make him look grand in the
presence of his female, herself deprived of these extravagances?
Perhaps also they are of use to him in certain works, even as the
trident helps Minotaurus in crumbling the pellets and carting the
rubbish. Implements of which we do not know the use always strike us as
singular. Having never associated with the West-Indian Hercules, I must
content myself with suspicions touching the purpose of his fearsome
equipment.
Well, one of the subjects in my voleries would achieve a similar savage
finery if he persisted in his attempts. I speak of Onthophagus Vacca.
His nymph has on its forehead a thick horn, one only, bent backward; on
its corselet it possesses a like horn, jutting forward. The two,
approaching their tips, look like a sort of pincers. What does the
insect lack in order to acquire, on a smaller scale, the eccentric
ornament of the West-Indian Scarab? It lacks perseverance. It matures
the appendage of the forehead and allows that of the corselet to perish
atrophied. It succeeds no better than Onthophagus Taurus in its attempt
to grow a pointed stake upon its chine; it loses a glorious opportunity
of making itself fine for the wedding and terrible in battle.
The others are no more successful. I bring up six different species.
All, in the chrysalis state, possess the thoracic horn and the
eight-pointed ventral coronet; not one benefits by these advantages,
which disappear altogether when the adult splits its case. My near
neighbourhood numbers a dozen species of Onthophagi; the world contains
some hundreds. All, natives and foreigners, have the same general
structure; all most probably possess the dorsal appendage at an early
age; and none of them, in spite of the variety of the climate, torrid
in one place, moderate in another, has succeeded in hardening it into a
permanent horn.
Could the future not complete a work the design of which is so very
clearly traced? We ask ourselves this the more readily inasmuch as
every appearance encourages the question. Examine under the
magnifying-glass the frontal horns of Onthophagus Taurus in the pupa
state; then consider as carefully the spear upon the corselet. At
first, there is no difference between them, except the general
configuration. In both cases, we find the same glassy aspect, the same
sheath swollen with a crystalline moisture, the same incipient organ
plainly marked. A leg in formation is not more clearly declared than
the horn on the corselet or those on the forehead.
Can time be lacking for the thoracic growth to organize itself into a
stiff and lasting appendage? The evolution of the nymph is swift; the
insect is perfect in a few weeks. Could it not be that, though this
brief space suffice to promote the maturity of the horns on the
forehead, the thoracic horn requires a longer time to ripen? Let us
prolong the nymphal period artificially and give the germ time to
develop itself. It seems to me that a decrease of temperature,
moderated and maintained for some weeks, for months if necessary,
should be capable of bringing about this result, by delaying the
progress of the evolution. Then, with a gentle slowness, favourable to
delicate formations, the promised organ will crystallize, so to speak,
and become the spear heralded by appearances.
The experiment attracted me. I was unable to undertake it for lack of
the means whereby to produce a cold, even and lasting temperature. What
should I have obtained if my penury had not made me abandon the
enterprise? A retarding of the progress of the metamorphosis, but
nothing more, apparently. The horn on the corselet would have persisted
in its sterility and, sooner or later, would have disappeared.
I have reasons for my conviction. The abode of the Onthophagus while
engaged on his metamorphosis is not deep down; variations of
temperature are easily felt. On the other hand, the seasons are
capricious, especially the spring. Under the skies of Provence, the
months of May and June, if the mistral lend a hand, have periods when
the thermometer drops in such a way as to suggest a return of winter.
To these vicissitudes let us add the influence of a more northerly
climate. The Onthophagi occupy a wide zone of latitude. Those of the
north, less favoured by the sun than those of the south, can, if
changing circumstances assist at the time of the transformation,
undergo long weeks of a decreased temperature which spins out the work
of evolution and ought therefore to permit the thoracic armour, at long
intervals and casually, to consolidate into a horn. Here and there,
then, the conditions of a moderate, or even cold temperature, at the
time of the nymphosis, are realized without the aid of my artifices.
Well, what becomes of this surplus time placed at the service of the
organic labour? Does the promised horn ripen? Not a bit of it: it
withers just as it does under the stimulus of a hot sun. The records of
entomology have never spoken of an Onthophagus carrying a horn upon his
corselet. No one would even have suspected the possibility of such an
armour, if I had not rumoured the strange appearance of the nymph. The
influence of climate, therefore, goes for nothing here.
Pushed further still, the question becomes more complicated. The horny
appendages of the Onthophagus, of the Copris, of Minotaurus and of so
many others are the male’s prerogative; the female is without them or
wears them only on a reduced and very modest scale. We must look upon
these corniculate products as personal ornaments much rather than as
implements of labour. The male makes himself fine for the pairing; but,
with the exception of Minotaurus, who pins down the dry pellet that
needs crushing and holds it in position with his trident, I know none
that uses his armour as a tool. Horns and prongs on the forehead,
crests and crescents on the corselet are jewels of masculine vanity and
nothing more. The other sex requires no such baits to attract suitors:
its femininity is enough; and finery is neglected.
Now here is something to give us food for thought. The nymph of the
Onthophagus of the female sex, a nymph with an unarmed forehead,
carries on its thorax a vitreous horn as long, as rich in promise as
that of the other sex. If this latter excrescence be an
incompletely-realized incipient ornament, then the former would be so
too, in which case the two sexes, both anxious for self-embellishment,
would work with equal zeal to grow a horn upon their thorax. We should
be witnessing the genesis of a species that would not be really an
Onthophagus, but a derivative of the group; we should be beholding the
commencement of singularities banished hitherto from among the
Dung-beetles, none of whom, of either sex, has thought of planting a
spear upon his chine. Stranger still: the female, always the more
humbly attired throughout the entomological order, would be vying with
the male in her propensity for eccentric adornment. An ambition of this
sort leaves me incredulous.
We must therefore believe that, if the possibilities of the future
should ever produce a Dung-beetle carrying a horn upon his corselet,
this upsetter of present customs will not be the Onthophagus succeeding
in maturing the thoracic appendage of the nymph, but rather an insect
resulting from a new model. The creative power throws aside the old
moulds and replaces them by others, fashioned with fresh care, after
plans of an inexhaustible variety. Its laboratory is not a peddling
rag-fair, where the living assume the cast clothes of the dead: it is a
medallist’s studio, where each effigy receives the stamp of a special
die. Its treasure-house of forms, of unbounded wealth, excludes any
niggardly patching of the old to make the new. It breaks up every mould
once used; it does away with it, without resorting to shabby
after-touches.
Then what is the meaning of those horny preparations, which are always
blighted before they come to aught? Without feeling greatly abashed by
my ignorance, I confess that I am absolutely unable to say. In the
absence of an appearance of learning, my answer has at least one merit,
that of perfect sincerity.
A DUNG-BEETLE OF THE PAMPAS