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THE THEORY OF PARASITISM




The Melecta does what she can with the gifts at her disposal. I should
leave it at that, if I had not to take into consideration a grave
charge brought against her. She is accused of having lost, for want of
use and through laziness, the workman's tools with which, so we are
told, she was originally endowed. Finding it to her advantage to do
nothing, bringing up her family free of expense, to the detriment of
others, she is alleged to have gradually inspired her race with an
abhorrence for work. The harvesting-tools, less and less often
employed, dwindled and perished as organs having no function; the
species changed into a different one; and finally idleness turned the
honest worker of the outset into a parasite. This brings us to a very
simple and seductive theory of parasitism, worthy to be discussed with
all respect. Let us set it forth.

Some mother, nearing the end of her labours and in a hurry to lay her
eggs, found, let us suppose, some convenient cells provisioned by her
fellows. There was no time for nest-building and foraging; if she
would save her family, she must perforce appropriate the fruit of
another's toil. Thus relieved of the tedium and fatigue of work, freed
of every care but that of laying eggs, she left a progeny which duly
inherited the maternal slothfulness and handed this down in its turn,
in a more and more accentuated form, as generation followed on
generation; for the struggle for life made this expeditious way of
establishing yourself one of the most favourable conditions for the
success of the offspring. At the same time, the organs of work, left
unemployed, became atrophied and disappeared, while certain details of
shape and colouring were modified more or less, so as to adapt
themselves to the new circumstances. Thus the parasitic race was
definitely established.

This race, however, was not too greatly transformed for us to be able,
in certain cases, to trace its origin. The parasite has retained more
than one feature of those industrious ancestors. So, for instance, the
Psithyrus is extremely like the Bumble-bee, whose parasite and
descendant she is. The Stelis preserves the ancestral characteristics
of the Anthidium; the Coelioxys-bee recalls the Leaf-cutter.

Thus speak the evolutionists, with a wealth of evidence derived not
only from correspondence in general appearance, but also from
similarity in the most minute particulars. Nothing is small: I am as
much convinced of that as any man; and I admire the extraordinary
precision of the details furnished as a basis for the theory. But am I
convinced? Rightly or wrongly, my turn of mind does not hold minutiae
of structure in great favour: a joint of the palpi leaves me rather
cold; a tuft of bristles does not appear to me an unanswerable
argument. I prefer to question the creature direct and to let it
describe its passions, its mode of life, its aptitudes. Having heard
its evidence, we shall see what becomes of the theory of parasitism.

Before calling upon it to speak, why should I not say what I have on
my mind? And mark me, first of all, I do not like that laziness which
is said to favour the animal's prosperity. I have also believed and I
still persist in believing that activity alone strengthens the present
and ensures the future both of animals and men. To act is to live; to
work is to go forward. The energy of a race is measured by the
aggregate of its action.

No, I do not like it at all, this idleness so much commended of
science. We have quite enough of these zoological brutalities: man,
the son of the Ape; duty, a foolish prejudice; conscience, a lure for
the simple; genius, neurosis; patriotism, jingo heroics; the soul, a
product of protoplasmic energies; God, a puerile myth. Let us raise
the war-whoop and go out for scalps; we are here only to devour one
another; the summum bonum is the Chicago packer's dollar-chest!
Enough, quite enough of that, without having transformism next to
break down the sacred law of work. I will not hold it responsible for
our moral ruin; it has not a sturdy enough shoulder to effect such a
breach; but still it has done its worst.

No, once more, I do not like those brutalities which, denying all that
gives some dignity to our wretched life, stifle our horizon under an
extinguisher of matter. Oh, don't come and forbid me to think, though
it were but a dream, of a responsible human personality, of
conscience, of duty, of the dignity of labour! Everything is linked
together: if the animal is better off, as regards both itself and its
race, for doing nothing and exploiting others, why should man, its
descendant, show greater scruples? The principle that idleness is the
mother of prosperity would carry us far indeed. I have said enough on
my own account; I will call upon the animals themselves, more eloquent
than I.

Are we so very sure that parasitic habits come from a love of
inaction? Did the parasite become what he is because he found it
excellent to do nothing? Is repose so great an advantage to him that
he abjured his ancient customs in order to obtain it? Well, since I
have been studying the Bee who endows her family with the property of
others, I have not yet seen anything in her that points to
slothfulness. On the contrary, the parasite leads a laborious life,
harder than that of the worker. Watch her on a slope blistered by the
sun. How busy she is, how anxious! How briskly she covers every inch
of the radiant expanse, how indefatigable she is in her endless
quests; in her visits, which are generally fruitless! Before coming
upon a nest that suits her, she has dived a hundred times into
cavities of no value, into galleries not yet victualled. And then,
however kindly her host, the parasite is not always well received in
the hostelry. No, it is not all roses in her trade. The expenditure of
time and labour which she finds necessary in order to house an egg may
easily equal or even exceed that of the worker in building her cell
and filling it with honey. That industrious one has regular and
continuous work, an excellent condition for success in her egg-laying;
the other has a thankless and precarious task, at the mercy of a
thousand accidents which endanger the great undertaking of installing
the eggs. One has only to watch the prolonged hesitation of a
Coelioxys seeking for the Leaf-cutters' cells to recognize that the
usurpation of another's nest is not effected without serious
difficulties. If she turned parasite in order to make the rearing of
her offspring easier and more prosperous, certainly she was very ill-
inspired. Instead of rest, hard work; instead of a flourishing family,
a meagre progeny.

To generalities, which are necessarily vague, we will add some precise
facts. A certain Stelis (Stelis nasuta, LATR.) is a parasite of the
Mason-bee of the Walls. When the Chalicodoma has finished building her
dome of cells upon her pebble, the parasite appears, makes a long
inspection of the outside of the home and proposes, puny as she is, to
introduce her eggs into this cement fortress. Everything is most
carefully closed: a layer of rough plaster, at least two-fifths of an
inch thick, entirely covers the central accumulation of cells, which
are each of them sealed with a thick mortar plug. And it is the honey
of these well-guarded chambers that has to be reached by piercing a
wall almost as hard as rock.

The parasite pluckily sets to; the idler becomes a glutton for work.
Atom by atom, she perforates the general enclosure and scoops out a
shaft just sufficient for her passage; she reaches the lid of the cell
and gnaws it until the coveted provisions appear in sight. It is a
slow and painful process, in which the feeble Stelis wears herself
out, for the mortar is much the same as Roman cement in hardness. I
myself find a difficulty in breaking it with the point of my knife.
What patient effort, then, the task requires from the parasite, with
her tiny pincers!

I do not know exactly how long the Stelis takes to make her entrance-
shaft, as I have never had the opportunity or rather the patience to
follow the work from start to finish; but what I do know is that a
Chalicodoma of the Walls, incomparably larger and stronger than the
parasite, when demolishing before my eyes the lid of a cell sealed
only the day before, was unable to complete her undertaking in one
afternoon. I had to come to her assistance in order to discover,
before the end of the day, the object of her housebreaking. When the
Mason-bee's mortar has once set, its resistance is that of stone. Now
the Stelis has not only to pierce the lid of the honey-store; she must
also pierce the general casing of the nest. What a time it must take
her to get through such a task, a gigantic one for her poor tools!

It is done at last, after infinite labour. The honey appears. The
Stelis slips through and, on the surface of the provisions, side by
side with the Chalicodoma's eggs, the number varying from time to
time. The victuals will be the common property of all the new
arrivals, whether the son of the house or strangers.

The violated dwelling cannot remain as it is, exposed to marauders
from without; the parasite must herself wall up the breach which she
has contrived. The quondam housebreaker becomes a builder. At the foot
of the pebble, the Stelis collects a little of that red earth which
characterizes our stony plateaus grown with lavender and thyme; she
makes it into mortar by wetting it with saliva; and with the pellets
thus prepared she fills up the entrance-shaft, displaying all the care
and art of a regular master-mason. Only, the work clashes in colour
with the Chalicodoma's. The Bee goes and gathers her cementing-powder
on the adjoining high-road, the metal of which consists of broken
flint-stones, and very seldom uses the red earth under the pebble
supporting the nest. This choice is apparently dictated by the fact
that the chemical properties of the former are more likely to produce
a solid structure. The lime of the road, mixed with saliva, yields a
harder cement than red clay would do. At any rate, the Chalicodoma's
nest is more or less white because of the source of its materials.
When a red speck, a few millimetres wide, appears on this pale
background, it is a sure sign that a Stelis has been that way. Open
the cell that lies under the red stain: we shall find the parasite's
numerous family established there. The rusty spot is an infallible
indication that the dwelling has been violated: at least, it is so in
my neighbourhood, where the soil is as I have described.

We see the Stelis, therefore, at first a rabid miner, using her
mandibles against the rock; next a kneader of clay and a plasterer
restoring broken ceilings. Her trade does not seem one of the least
arduous. Now what did she do before she took to parasitism? Judging
from her appearance, the transformists tell us that she was an
Anthidium, that is to say, she used to gather the soft cotton-wool
from the dry stalks of the lanate plants and fashion it into wallets,
in which to heap up the pollen-dust which she gleaned from the flowers
by means of a brush carried on her abdomen. Or else, springing from a
genus akin to the cotton-workers, she used to build resin partitions
in the spiral stairway of a dead Snail. Such was the trade driven by
her ancestors.

Really! So, to avoid slow and painful work, to achieve an easy life,
to give herself the leisure favourable to the settlement of her
family, the erstwhile cotton-presser or collector of resin-drops took
to gnawing hardened cement! She who once sipped the nectar of flowers
made up her mind to chew concrete! Why, the poor wretch toils at her
filing like a galley-slave! She spends more time in ripping up a cell
than it would take her to make a cotton wallet and fill it with food.
If she really meant to progress, to do better in her own interest and
that of her family, by abandoning the delicate occupations of the old
days, we must confess that she has made a strange mistake. The mistake
would be no greater if fingers accustomed to fancy-weaving were to lay
aside velvet and silk and proceed to handle the quarryman's blocks or
to break stones on the roadside.

No, the animal does not commit the folly of voluntarily embittering
its lot; it does not, in obedience to the promptings of idleness, give
up one condition to embrace another and a more irksome; should it
blunder for once, it will not inspire its posterity with a wish to
persevere in a costly delusion. No, the Stelis never abandoned the
delicate art of cotton-weaving to break down walls and to grind
cement, a class of work far too unattractive to efface the memory of
the joys of harvesting amid the flowers. Indolence has not evolved her
from an Anthidium. She has always been what she is to-day: a patient
artificer in her own line, a steady worker at the task that has fallen
to her share.

That hurried mother who first, in remote ages, broke into the abode of
her fellows to secure a home for her eggs found this unscrupulous
method, so you tell us, very favourable to the success of her race, by
virtue of its economy of time and trouble. The impression left by this
new policy was so profound that heredity bequeathed it to posterity,
in ever-increasing proportions, until at last parasitic habits became
definitely fixed. The Chalicodoma of the Sheds, followed by the Three-
horned Osmia, will teach us what to think of this conjecture.

I have described in an earlier chapter my installation of Chalicodoma-
hives against the walls of a porch facing the south. Here, on a level
with my head, placed so that they can easily be observed, hang some
tiles removed from the neighbouring roofs in winter, together with
their enormous nests and their occupants. Every May, for five or six
years in succession, I have assiduously watched the works of my Mason-
bees. From the mass of my notes on the subject I take the following
experiments which bear upon the matter under discussion.

Long ago, when I used to scatter a handful of Chalicodomae some way
from home, in order to study their capacity for finding their nest
again, I noticed that, if they were too long absent, the laggards
found their cells closed on their return. Neighbours had taken the
opportunity to lay their eggs there, after finishing the building and
stocking it with provisions. The abandoned property benefited another.
On realizing the usurpation, the Bee returning from her long journey
soon consoled herself for the mishap. She began to break the seals of
some cell or other, adjoining her own; the rest let her have her way,
being doubtless too busy with their present labours to seek a quarrel
with the freebooter. As soon as she had destroyed the lid, the Bee,
with a sort of feverish haste that burned to repay theft by theft, did
a little building, did a little victualling, as though to resume the
thread of her occupations, destroyed the egg in being, laid her own
and closed the cell again. Here was a touch of nature that deserved
careful examination.

At eleven o'clock in the morning, when the work is at its height, I
mark half-a-score of Chalicodomae with different colours, to
distinguish them from one another. Some are occupied with building,
others are disgorging honey. I mark the corresponding cells in the
same way. As soon as the marks are quite dry, I catch the ten Bees,
place them singly in screws of paper and shut them all in a box until
the next morning. After twenty-four hours' captivity, the prisoners
are released. During their absence, their cells have disappeared under
a layer of recent structures; or, if still exposed to view, they are
closed and others have made use of them.

As soon as they are free, the ten Bees, with one exception, return to
their respective tiles. They do more than this, so accurate is their
memory, despite the confusion resulting from a prolonged
incarceration: they return to the cell which they have built, the
beloved stolen cell; they minutely explore the outside of it, or at
least what lies nearest to it, if the cell has disappeared under the
new structures. In cases where the home is not henceforward
inaccessible, it is at least occupied by a strange egg and the door is
securely fastened. To this reverse of fortune the ousted ones retort
with the brutal lex talionis: an egg for an egg, a cell for a cell.
You've stolen my house; I'll steal yours. And, without much
hesitation, they proceed to force the lid of a cell that suits them.
Sometimes they recover possession of their own home, if it is possible
to get into it; sometimes and more frequently they seize upon some one
else's, even at a considerable distance from their original dwelling.

Patiently they gnaw the mortar lid. As the general rough-cast covering
all the cells is not applied until the end of the work, all that they
need do is to demolish the lid, a hard and wearisome task, but not
beyond the strength of their mandibles. They therefore attack the
door, the cement disk, and reduce it to dust. The criminal is allowed
to carry out her nefarious designs without the slightest interference
or protest from any of her neighbours, though these must necessarily
include the chief party interested. The Bee is as forgetful of her
cell of yesterday as she is jealous of her actual cell. To her the
present is everything; the past means nothing; and the future means no
more. And so the population of the tile leave the breakers of doors to
do their business in peace; none hastens to the defence of a home that
might well be her own. How differently things would happen if the cell
were still on the stocks! But it dates back to yesterday, to the day
before; and no one gives it another thought.

It's done: the lid is demolished; access is free. For some time, the
Bee stands bending over the cell, her head half-buried in it, as
though in contemplation. She goes away, she returns undecidedly; at
last she makes up her mind. The egg is snapped up from the surface of
the honey and flung on the rubbish-heap with no more ceremony than if
the Bee were ridding the house of a bit of dirt. I have witnessed this
hideous crime again and yet again; I confess to having repeatedly
provoked it. In housing her egg, the Mason-bee displays a brutal
indifference to the fate of her neighbour's egg.

I see some of them afterwards busy provisioning, disgorging honey and
brushing pollen into the cell already completely provisioned; I see
some masoning a little at the orifice, or at least laying on a few
trowels of mortar. It seems as if the Bee, although the victuals and
the building are just as they should be, were resuming the work at the
point at which she left it twenty-four hours before. Lastly, the egg
is laid and the opening closed up. Of my captives, one, less patient
than the rest, rejects the slow process of eating away the cover and
decides in favour of robbery with violence, on the principle that
might is right. She dislodges the owner of a half-stocked cell, keeps
good watch for a long time on the threshold of the home and, when she
feels herself the mistress of the house, goes on with the
provisioning. I follow the ousted proprietress with my eyes. I see her
seize upon a closed cell by breaking into it, behaving in all respects
like my imprisoned Chalicodomae.

The whole occurrence was too significant to be left without further
confirmation. I repeated the experiment, therefore, almost every year,
always with the same success. I can only add that, among the Bees
placed by my artifices under the necessity of making up for lost time,
a few are of a more easy-going temperament. I see some building anew,
as if nothing out of the way had happened; others--this is a very rare
course--going to settle on another tile, as though to avoid a society
of thieves; and lastly a few who bring pellets of mortar and zealously
finish the lid of their own cell, although it contains a strange egg.
However, housebreaking is the usual thing.

One more detail not without value: it is not necessary for you to
intervene and imprison Mason-bees for a time in order to witness the
acts of violence which I have described. If you follow the work of the
swarm assiduously, you may occasionally find a surprise awaiting you.
A Mason-bee will appear and, for no reason known to you, break open a
door and lay her egg in the violated cell. From what goes before, I
look upon the Bee as a laggard, kept away from the workyard by an
accident, or else carried to a distance by a gust of wind. On
returning after an absence of some duration, she finds her place
taken, her cell used by another. The victim of an usurper's villainy,
like the prisoners in my paper screws, she behaves as they do and
indemnifies herself for her loss by breaking into another's home.

Lastly, it was a matter of learning the behaviour, after their act of
violence, of the Masons who have smashed in a door, brutally expelled
the egg within and replaced it by one of their own laying. When the
lid is repaired to look as good as new and everything restored to
order, will they continue their burglarious ways and exterminate the
eggs of others to make room for their own? By no means. Revenge, that
pleasure of the gods and perhaps also of Bees, is satisfied after one
cell has been ripped open. All anger is appeased when the egg for
which so much work has been done is safely housed. Henceforth, both
prisoners and stray laggards resume their ordinary labours,
indifferently with the rest. They build honestly, they provision
honestly, nor meditate further evil. The past is quite forgotten until
a fresh disaster occurs.

To return to the parasites: a mother chanced to find herself the
mistress of another's nest. She took advantage of this to entrust her
egg to it. This expeditious method, so easy for the mother and so
favourable to the success of her offspring, made such an impression on
her that she transmitted the maternal indolence to her posterity. Thus
the worker gradually became transformed into a parasite.

Capital! The thing goes like clockwork, as long as we have only to put
our ideas on paper. But let us just consult the facts, if you don't
mind; before arguing about probabilities, let us look into things as
they are. Here is the Mason-bee of the Sheds teaching us something
very curious. To smash the lid of a cell that does not belong to her,
to throw the egg out of doors and put her own in its place is a
practice which she has followed since time began. There is no need of
my interference to make her commit burglary: she commits it of her own
accord, when her rights are prejudiced as the result of a too-long
absence. Ever since her race has been kneading cement, she has known
the law of retaliation. Countless ages, such as the evolutionists
require, have made her adopt forcible usurpation as an inveterate
habit. Moreover, robbery is so incomparably easy for the mother. No
more cement to scratch up with her mandibles on the hard ground, no
more mortar to knead, no more clay walls to build, no more pollen to
gather on hundreds and hundreds of journeys. All is ready, board and
lodging. Never was a better opportunity for allowing one's self a good
time. There is nothing against it. The others, the workers, are
imperturbable in their good-humour. Their outraged cells leave them
profoundly indifferent. There are no brawls to fear, no protests. Now
or never is the moment to tread the primrose path.

Besides, your progeny will be all the better for it. You can choose
the warmest and wholesomest spots; you can multiply your laying-
operations by devoting to them all the time that you would have to
spend on irksome occupations. If the impression produced by the
violent seizure of another's property is strong enough to be handed
down by heredity, how deep should be the impression of the actual
moment when the Mason-bee is in the first flush of success! The
precious advantage is fresh in the memory, dating from that very
instant; the mother has but to continue in order to create a method of
installation favourable in the highest degree to her and hers. Come,
poor Bee! Throw aside your exhausting labours, follow the
evolutionists' advice and, as you have the means at your disposal,
become a parasite!

But no, having effected her little revenge, the builder returns to her
masonry, the gleaner to her gleaning, with unquenchable zeal. She
forgets the crime committed in a moment of anger and takes good care
not to hand down any tendency towards idleness to her offspring. She
knows too well that activity is life, that work is the world's great
joy. What myriads of cells has she not broken open since she has been
building; what magnificent opportunities, all so clear and conclusive,
has she not had to emancipate herself from drudgery! Nothing could
convince her: born to work, she persists in an industrious life. She
might at least have produced an offshoot, a race of housebreakers, who
would invade cells by demolishing doors. The Stelis does something of
the kind; but who would think of proclaiming a relationship between
the Chalicodoma and her? The two have nothing in common. I call for a
scion of the Mason-bee of the Sheds who shall live by the art of
breaking through ceilings. Until they show me one, the theorists will
only make me smile when they talk to me of erstwhile workers
relinquishing their trade to become parasitic sluggards.

I also call, with no less insistence, for a descendant of the Three-
horned Osmia, a descendant given to demolishing party-walls. I will
describe later how I managed to make a whole swarm of these Osmiae
build their nests on the table in my study, in glass tubes that
enabled me to see the inmost secrets of the work of the Bee. (Cf.
"Bramble-bees and Others", by J. Henri Fabre, translated by Alexander
Teixeira de Mattos: chapters 1 to 7.--Translator's Note.) For three or
four weeks, each Osmia is scrupulously faithful to her tube, which is
laboriously filled with a set of chambers divided by earthen
partitions. Marks of different colours painted on the thorax of the
workers enable me to recognize individuals in the crowd. Each crystal
gallery is the exclusive property of one Osmia; no other enters it,
builds in it or hoards in it. If, through heedlessness, through
momentary forgetfulness of her own house in the tumult of the city,
some neighbour so much as comes and looks in at the door, the owner
soon puts her to flight. No such indiscretion is tolerated. Every Bee
has her home and every home its Bee.

All goes well until just before the end of the work. The tubes are
then closed at the orifice with a thick plug of earth; nearly the
whole swarm has disappeared; there remain on the spot a score of
tatterdemalions in threadbare fleeces, worn out by a month's hard
toil. These laggards have not finished their laying. There is no lack
of unoccupied tubes, for I take care to remove some of those which are
full and to replace them by others that have not yet been used. Very
few of the Bees decide to take possession of these new homes, which
differ in no particular from the earlier ones; and even then they
build only a small number of cells, which are often mere attempts at
partitions.

They want something different: a nest belonging to some one else. They
bore through the stopper of the inhabited tubes, a work of no great
difficulty, for we have here not the hard cement of the Chalicodoma,
but a simple lid of dried mud. When the entrance is cleared, a cell
appears, with its store of provisions and its egg, with her brutal
mandibles; she rips it open and goes and flings it away. She does
worse: she eats it on the spot. I had to witness this horror many
times over before I could accept it as a fact. Note that the egg
devoured may very well contain the criminal's own offspring.
Imperiously swayed by the needs of her present family, the Osmia puts
her past family entirely out of her mind.

Having perpetrated this child-murder, the depraved creature does a
little provisioning. They all experience the same necessity to go
backwards in the sequence of actions in order to pick up the thread of
their interrupted occupations. Her next work is to lay her egg and
then she conscientiously restores the demolished lid.

The havoc can be more sweeping still. One of these laggards is not
satisfied with a single cell; she needs two, three, four. To reach the
most remote, the Osmia wrecks all those which come before it. The
partitions are broken down, the eggs eaten or thrown away, the
provisions swept outside and often even carried to a distance in great
lumps. Covered with dust from the loose plaster of the demolition,
floured all over with the rifled pollen, sticky with the contents of
the mangled eggs, the Osmia, while at her brigand's work, is altered
beyond recognition. Once the place is cleared, everything resumes its
normal course. Provisions are laboriously brought to take the place of
those which have been thrown away; eggs are laid, one on each heap of
food; the partitions are built up again; and the massive plug sealing
the whole structure is made as good as new.

Crimes of this kind recur so often that I am obliged to interfere and
place in safety the nests which I wish to keep intact. And nothing as
yet explains this brigandage, bursting forth at the end of the work
like a moral epidemic, like a frenzied delirium. I should say nothing
if the site were lacking; but the tubes are there, close by, empty and
quite fit to receive the eggs. The Osmia refuses them, she prefers to
plunder. Is it from weariness, from a distaste for work after a period
of fierce activity? Not at all; for, when a row of cells has been
stripped of its contents, after the ravage and waste, she has to come
back to ordinary work, with all its burdens. The labour is not
reduced; it is increased. It would pay the Bee infinitely better, if
she wants to continue her laying, to make her home in an unoccupied
tube. The Osmia thinks differently. Her reasons for acting as she does
escape me. Can there be ill-conditioned characters among her,
characters that delight in a neighbour's ruin? There are among men.

In the privacy of her native haunts, the Osmia, I have no doubt,
behaves as in my crystal galleries. Towards the end of the building-
operations, she violates others' dwellings. By keeping to the first
cell, which it is not necessary to empty in order to reach the next,
she can utilize the provisions on the spot and shorten to that extent
the longest part of her work. As usurpations of this kind have had
ample time to become inveterate, to become inbred in the race, I ask
for a descendant of the Osmia who eats her grandmother's egg in order
to establish her own egg.

This descendant I shall not be shown; but I may be told that she is in
process of formation. The outrages which I have described are
preparing a future parasite. The transformists dogmatize about the
past and dogmatize about the future, but as seldom as possible talk to
us about the present. Transformations have taken place,
transformations will take place; the pity of it is that they are not
actually taking place. Of the three tenses, one is lacking, the very
one which directly interests us and which alone is clear of the
incubus of theory. This silence about the present does not please me
overmuch, scarcely more than the famous picture of "The Crossing of
the Red Sea" painted for a village chapel. The artist had put upon the
canvas a broad ribbon of brightest scarlet; and that was all.

'Yes, that's the Red Sea,' said the priest, examining the masterpiece
before paying for it. 'That's the Red Sea, right enough; but where are
the Israelites?'

'They have passed,' replied the painter.

'And the Egyptians?'

'They are on the way.'

Transformations have passed, transformations are on the way. For
mercy's sake, cannot they show us transformations in the act? Must the
facts of the past and the facts of the future necessarily exclude the
facts of the present? I fail to understand.

I call for a descendant of the Chalicodoma and a descendant of the
Osmia who have robbed their neighbours with gusto, when occasion
offered, since the origin of their respective races, and who are
working industriously to create a parasite happy in doing nothing.
Have they succeeded? No. Will they succeed? Yes, people maintain. For
the moment, nothing. The Osmiae and Chalicodomae of to-day are what
they were when the first trowel of cement or mud was mixed. Then how
many ages does it take to form a parasite? Too many, I fear, for us
not to be discouraged.

If the sayings of the theorists are well-founded, going on strike and
living by shifts was not always enough to assure parasitism. In
certain cases, the animal must have had to change its diet, to pass
from live prey to vegetarian fare, which would entirely subvert its
most essential characteristics. What should we say to the Wolf giving
up mutton and browsing on grass, in obedience to the dictates of
idleness? The boldest would shrink from such an absurd assumption. And
yet transformism leads us straight to it.

Here is an example: in July, I split some bramble-stems in which Osmia
tridentata has built her nests. In the long series of cells, the lower
already hold the Osmia's cocoons, while the upper contain the larva
which has nearly finished consuming its provisions and the topmost
show the victuals untouched, with the Osmia's egg upon them. It is a
cylindrical egg, rounded at both extremities, of a transparent white
and measuring four to five millimetres in length. (.156 to .195 inch.-
-Translator's Note.) It lies slantwise, one end of it resting on the
food and the other sticking up at some distance above the honey. Now,
by multiplying my visits to the fresh cells, I have on several
occasions made a very valuable discovery. On the free end of the
Osmia's egg, another egg is fixed; an egg quite different in shape,
white and transparent like the first, but much smaller and narrower,
blunt at one end and tapering into a rather sharp point at the other.
It is two millimetres long by half a millimetre wide. (.078 and .019
inch.--Translator's Note.) It is undeniably the egg of a parasite, a
parasite which compels my attention by its curious method of
installing its family.

It opens before the Osmia's egg. The tiny grub, as soon as it is born,
begins to drain the rival egg, of which it occupied the top part, high
up above the honey. The extermination soon becomes perceptible. You
can see the Osmia's egg turning muddy, losing its brilliancy, becoming
limp and wrinkled. In twenty-four hours, it is nothing but an empty
sheath, a crumpled bit of skin. All competition is now removed; the
parasite is the master of the house. The young grub, when demolishing
the egg, was active enough: it explored the dangerous thing which had
to be got rid of quickly, it raised its head to select and multiply
the attacking-points. Now, lying at full length on the surface of the
honey, it no longer shifts its position; but the undulations of the
digestive canal betray its greedy absorption of the Osmia's store of
food. The provisions are finished in a fortnight and the cocoon is
woven. It is a fairly firm ovoid, of a very dark-brown colour, two
characteristics which at once distinguish it from the Osmia's pale,
cylindrical cocoon. The hatching takes place in April or May. The
puzzle is solved at last: the Osmia's parasite is a Wasp called the
Spotted Sapyga (Sapyga punctata, V.L.)

Now where are we to class this Wasp, a true parasite in the strict
sense of the word, that is to say, a consumer of others' provisions.
Her general appearance and her structure make it clear to any eye more
or less familiar with entomological shapes that she belongs to a
species akin to that of the Scoliae. Moreover, the masters of
classification, so scrupulous in their comparison of characteristics,
agree in placing the Sapygae immediately after the Scoliae and a
little before the Mutillae. The Scoliae feed their grubs on prey; so
do the Mutillae. The Osmia's parasite, therefore, if it really derives
from a transformed ancestor, is descended from a flesh-eater, though
it is now an eater of honey. The Wolf does more than become a Sheep:
he turns himself into a sweet-tooth.

'You will never get an apple-tree out of an acorn,' Franklin tells us,
with that homely common-sense of his.

In this case, the passion for jam must have sprung from a love of
venison. Any theory might well be deficient in balance when it leads
to such vagaries as this.

I should have to write a volume if I would go on setting forth my
doubts. I have said enough for the moment. Man, the insatiable
enquirer, hands down from age to age his questions about the whys and
wherefores of origins. Answer follows answer, is proclaimed true
to-day and recognized as false tomorrow; and the goddess Isis
continues veiled.





Next: THE TRIBULATIONS OF THE MASON BEE

Previous: PARASITES



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