A PARASITE OF THE MAGGOT





The dangers of the exhumation are not the only ones; the Bluebottle

must be acquainted with others. Life, when all is said, is a

knacker's yard wherein the devourer of today becomes the devoured

of tomorrow; and the robber of the dead cannot fail to be robbed of

her own life when the time comes. I know that she has one

exterminator in the person of the tiny Saprinus beetle, a fisher of

fat sausages on the edge of the pools formed by liquescent corpses.

Here swarm in common the grubs of the greenbottle, the flesh fly

and the bluebottle. The Saprinus draws them to him from the bank

and gobbles them indiscriminately. They represent to him morsels

of equal value.



This banquet can be observed only in the open country, under the

rays of a hot sun. Saprini and greenbottles never enter our

houses; the flesh fly visits us but discreetly, does not feel at

home with us; the only one who comes fussing along is the

bluebottle, who thus escapes the tribute due to the consumer of

plump sausages. But, in the fields, where she readily lays her

eggs upon any carcass that she finds, she, as well as the others,

sees her vermin swept away by the gluttonous Saprinus.



In addition, graver disasters decimate her family, if, as I do not

doubt, we can apply to the bluebottle what I have seen happen in

the case of her rival, the flesh fly. So far, I have had no

opportunity of actually perceiving with the first what I have to

tell of the second; still, I do not hesitate to repeat about the

one what observation has taught me about the other, for the larval

analogies between the two flies are very close.



Here are the facts. I have gathered a number of pupae of the flesh

fly in one of my vermin jars. Wishing to examine the pupa's hinder

end, which is hollowed into a cup and scalloped into a coronet, I

stave in one of the little barrels and force open the last segments

with the point of my pocketknife. The horny keg does not contain

what I expected to find: it is full of tiny grubs packed one atop

the other with the same economy of space as anchovies in a bottle.

Save for the skin, which has hardened into a brown shell, the

substance of the maggot has disappeared, changed into a restless

swarm.



There are thirty-five occupants. I replace them in their casket.

The rest of my harvest, wherein, no doubt, are other pupae

similarly stocked, is arranged in tubes that will easily show me

what happens. The thing to discover is what genus of parasites the

grubs enclosed belong to. But it is not difficult, without waiting

for the hatching of the adults, to recognize their nature merely by

their mode of life. They form part of the family of Chalcididae,

who are microscopic ravagers of living entrails.



Not long ago, in winter, I took from the chrysalis of a great

peacock moth four hundred and forty-nine parasites belonging to the

same group. The whole substance of the future moth had

disappeared, all but the nymphal wrapper, which was intact and

formed a handsome Russia-leather wallet. The worm grubs were here

heaped up and squeezed together to the point of sticking to one

another. The hair pencil extracts them in bundles and cannot

separate them without some difficulty. The holding capacity is

strained to the utmost; the substance of the vanished Moth would

not fill it better. That which died has been replaced by a living

mass of equal dimensions, but subdivided. The price of this

colony's existence is the conversion of the chrysalis into a sort

of milk food of doubtful constitution. The enormous udder has been

drained outright.



You shudder when you think of that budding flesh nibbled bit by bit

by four or five hundred gormandizers; the horrified imagination

refuses to picture the anguish suffered by the tortured wretch.

But is there really any pain? We have leave to doubt it. Pain is

a patent of nobility; it is more pronounced in proportion as the

sufferer belongs to a higher order. In the lower ranks of animal

life, it must be greatly reduced, perhaps even nil, especially when

life, in the throes of evolution, has not yet acquired a stable

equilibrium. The white of an egg is living matter, but endures the

prick of a needle without a quiver. Would it not be the same with

the chrysalis of the great peacock, dissected cell by cell by

hundreds of infinitesimal anatomists? Would it not be the same

with the pupa of the flesh fly? These are organisms put back into

the crucible, reverting to the egg state for a second birth. There

is reason to believe, therefore, that their destruction crumb by

crumb is merciful.



Towards the end of August, the parasite of the flesh fly's grubs

makes her appearance out of doors in the adult form. She is a

Chalcidid, as I expected. She issues from the barrel through one

or two little round holes which the prisoners have pierced with a

patient tooth. I count some thirty to each pupa. There would not

be enough room in the abode if the family were larger.



The imp is a slim and elegant creature, but oh, how small! She

measures hardly two millimeters. Her garb is bronzed black, with

pale legs and a heart shaped, pointed, slightly pedunculate

abdomen, with never a trace of a probe for inoculating the eggs.

The head is transversal, the width exceeding the length.



The male is only half the size of the female; he is also very much

less numerous. Perhaps pairing is here, as we see elsewhere, a

secondary matter from which it is possible to abstain, in part,

without injuring the prospects of the race. Nevertheless, in the

tube wherein I have housed the swarm, the few males lost among the

crowd ardently woo the passing fair. There is much to be done

outside, as long as the flesh fly's season lasts; things are

urgent; and each pigmy hurries as fast as she can to take up her

part as an exterminator.



How is the parasite's inroad into the flesh fly's pupae effected?

Truth is always veiled in a certain mystery. The good fortune that

secured me the ravaged pupa taught me nothing concerning the

tactics of the ravager. I have never seen the Chalcidid explore

the contents of my appliances; my attention was engaged elsewhere

and nothing is so difficult to see as a thing not yet suspected.

But, though direct observation be lacking, logic will tell us

approximately what we want to know.



It is evident, to begin with, that the invasion cannot have been

made through the sturdy amour of the pupae. This is too hard to be

penetrated by the means at the pigmy's disposal. Naught but the

delicate skin of the maggots lends itself to the introduction of

the germs. An egg laying mother, therefore, appears, inspects the

surface of the pool of sanies swarming with grubs, selects the one

that suits her and perches on it; then, with the tip of her pointed

abdomen, whence emerges, for an instant, a short probe kept hidden

until then, she operates on the patient, perforating his paunch

with a dexterous wound into which the germs are inserted.

Probably, a number of pricks are administered, as the presence of

thirty parasites seems to demand.



Anyway, the maggot's skin is pierced at either one point or many;

and this happens while the grub is swimming in the pools formed by

the putrid flesh. Having said this, we are faced with a question

of serious interest. To set it forth necessitates a digression

which seems to have nothing to do with the subject in hand and is

nevertheless connected with it in the closest fashion. Without

certain preliminaries, the remainder would be unintelligible. So

now for the preliminaries.



I was in those days busy with the poison of the Languedocian

scorpion and its action upon insects. To direct the sting toward

this or the other part of the victim and moreover to regulate its

emission would be absolutely impossible and also very dangerous, as

long as the scorpions were allowed to act as they pleased. I

wished to be able myself to choose the part to be wounded; I

likewise wished to vary the dose of poison at will. How to set

about it? The scorpion has no jarlike receptacle in which the

venom is accumulated and stored, like that possessed, for instance,

by the wasp and the bee. The last segment of the tail, gourd

shaped and surmounted by the sting, contains only a powerful mass

of muscles along which lie the delicate vessels that secrete the

poison.



In default of a poison jar which I would have placed on one side

and drawn upon at my convenience, I detach the last segment,

forming the base of the sting. I obtain it from a dead and already

withered scorpion. A watch glass serves as a basin. Here, I tear

and crush the piece in a few drops of water and leave it to steep

for four-and-twenty hours. The result is the liquid which I

propose to use for the inoculation. If any poison remained in my

animal's caudal gourd, there must be at least some traces of it in

the infusion in the watch glass.



My hypodermic syringe is of the simplest. It consists of a little

glass tube, tapering sharply at one end. By drawing in my breath,

I fill it with the liquid to be tested; I expel the contents by

blowing. Its point is almost as fine as a hair and enables me to

regulate the dose to the degree which I want. A cubic millimeter

is the usual charge. The injection has to be made at parts that

are generally covered with horn. So as not to break the point of

my fragile instrument, I prepare the way with a needle, with which

I prick the victim at the spot required. I insert the tip of the

loaded injector in the hole thus made and I blow. The thing is

done in a moment, very neatly and in an orthodox fashion, favorable

to delicate experiments. I am delighted with my modest apparatus.



I am equally delighted with the results. The scorpion himself,

when wounding with his sting, in which the poison is not diluted as

mine is in the watch glass, would not produce effects like those of

my pricks. Here is something more brutal, producing more

convulsion in the sufferer. The virus of my contriving excels the

scorpion's.



The test is several times repeated, always with the same mixture,

which, drying up by spontaneous evaporation, then made to serve

again by the addition of a few drops of water, once more drained

and once more moistened, does duty for an indefinite length of

time. Instead of abating, the virulence increases. Moreover, the

corpses of the insects operated upon undergo a curious change,

unknown in my earlier observations. Then the suspicion comes to me

that the actual poison of the scorpion does not enter into the

matter at all. What I obtain with the end joint of the tail, with

the gland at the base of the sting, I ought to obtain with any

other part of the animal.



I crush in a few drops of water a joint of the tail taken from the

front portion, far from the poison glands. After soaking it for

twenty-four hours, I obtain a liquid whose effects are absolutely

the same as those before, when I used the joint that bears the

sting. I try again with the scorpion's claws, the contents of

which consist solely of muscle. The results are just the same.

The whole of the animal's body, therefore, no matter which fragment

be submitted to the steeping process, yields the virus that so

greatly pricks my curiosity.



Every part of the Spanish fly [Cantharis or blistering beetle],

inside and out, is saturated with the blistering element; but there

is nothing like this in the scorpion, who localizes his venom in

his caudal gland and has none of it elsewhere. The cause of the

effects which I observe is therefore connected with general

properties which I ought to find in any insect, even the most

harmless.



I consult Oryctes nasicornis, the peaceable rhinoceros beetle, on

this subject. To get at the exact nature of the materials, instead

of pulverizing the whole insect in a mortar, I use merely the

muscular tissue obtained by scraping the inside of the dried

Oryctes' corselet. Or else I extract the dry contents of the hind

legs. I do the same with the desiccated corpses of the cockchafer,

the Capricorn, or Cerambyx beetle, and the Cetonia, or rosechafer.

Each of my gleanings, with a little water added, is left to soften

for a couple of days in a watch glass and yields to the liquid

whatever can be extracted from it by crushing and dissolving.



This time, we take a great step forward. All my preparations,

without distinction, are horribly virulent. Let the reader judge.

I select as my first patient the sacred beetle, Scarabaeus sacer,

who thanks to his size and sturdiness, lends himself admirably to

an experiment of this kind. I operate upon a dozen, in the

corselet, on the breast, on the belly and, by preference, on one of

the hind legs, far removed from the impressionable nervous centers.

No matter what part my injector attacks, the effect produced is the

same, or nearly. The insect falls as though struck by lightning.

It lies on its back and wriggles its legs, especially the hind

legs. If I set it on its feet again, I behold a sort of St.

Vitus' dance. Scarabaeus lowers his head, arches his back, draws

himself up on his twitching legs. He marks time with his feet on

the ground, moves forward a little, moves as much backward, leans

to the right, leans to the left, in wild disorder, incapable of

keeping his balance or making progress. And this happens with

sudden jerks and jolts, with a vigor no whit inferior to that of

the animal in perfect health. It is a displacement of all the

works, a storm that uproots the mutual relations of the muscles.



Seldom have I witnessed such sufferings, in my career as a cross-

examiner of animals and, therefore, as a torturer. I should feel a

scruple, did I not foresee that the grain of sand shifted today may

one day help us by taking its place in the edifice of knowledge.

Life is everywhere the same, in the Dung beetle's body as in man's.

To consult it in the insect means consulting it in ourselves, means

moving towards vistas which we cannot afford to neglect. That hope

justifies my cruel studies, which, though apparently so puerile,

are in reality worthy of serious consideration.



Of my dozen sufferers, some rapidly succumb, others linger for a

few hours. They are all dead by tomorrow. I leave the corpses on

the table, exposed to the air. Instead of drying and stiffening,

like the asphyxiated insects intended for our collections, my

patients, on the contrary, turn soft and slacken in the joints,

notwithstanding the dryness of the surrounding air; they become

disjointed and separate into loose pieces, which are easily

removed.



The results are the same with the Capricorn, the cockchafer, the

Procrustes [a large ground beetle], the Carabus [the true ground

beetle, including the gold beetle]. In all of them there is a

sudden break-up, followed by speedy death, a slackening of the

joints and swift putrefaction. In a non-horny victim, the quick

chemical changes of the tissues are even more striking. A Cetonia

grub, which resists the scorpion's sting, even though repeatedly

administered, dies in a very short time if I inject a tiny drop of

my terrible fluid into any part of its body. Moreover, it turns

very brown and, in a couple of days, becomes a mass of black

putrescence.



The great peacock, that large moth who recks little of the

scorpion's poison, is no more able to resist my inoculations than

the sacred beetle and the others. I prick two in the belly, a male

and a female. At first, they seem to bear the operation without

distress. They grip the trellis work of the cage and hang without

moving, as though indifferent. But soon the disease has them in

its grip. What we see is not the tumultuous ending of the sacred

beetle; it is the calm advent of death. With wings slackly

quivering, softly they die and drop from the wires. Next day, both

corpses are remarkably lax; the segments of the abdomen separate

and gape at the least touch. Remove the hairs and you shall see

that the skin, which was white, has turned brown and is changing to

black. Corruption is quickly doing its work.



This would be a good opportunity to speak of bacteria and cultures.

I shall do nothing of the sort. On the hazy borderland of the

visible and the invisible, the microscope inspires me with

suspicion. It so easily replaces the eye of reality by the eye of

imagination; it is so ready to oblige the theorists with just what

they want to see. Besides, supposing the microbe to be found, if

that were possible, the question would be changed, not solved. For

the problem of the collapse of the structure through the fact of a

prick there would be substituted another no less obscure: how does

the said microbe bring about that collapse? In what way does it go

to work? Where lies its power?



Then what explanation shall I give of the facts which I have just

set forth? Why, none, absolutely none, seeing that I do not know

of any. As I am unable to do better, I will confine myself to a

pair of comparisons or images, which may serve as a brief resting

place for the mind on the dark billows of the unknown.



All of us, as children, have amused ourselves with the game of

"card friars." A number of cards, as many as possible, are bent

lengthwise into a semi-cylinder. They are placed on a table, one

behind the other, in a winding row, the spaces in which are

suitably disposed. The performance pleases the eye by its curved

lines and its regular arrangement. It possesses order, which is a

condition of all animated matter. You give a little tap to the

first card. It falls and overturns the second, which, in the same

way, topsy-turvies the third; and so on, right to the end of the

row. In less than no time, the capsizing wave spreads and the

handsome edifice is shattered. Order is succeeded by disorder, I

might almost say, by death. What was needed thus to upset the

procession of friars? A very, very slight first push, out of all

proportion to the toppled mass.



Again, take a glass balloon containing a solution of alum

supersaturated by heat. It is closed, during the process of

boiling, with a cork and is then allowed to cool. The contents

remain fluid and limpid for an indefinite period. Mobility is here

represented by a faint semblance of life. Remove the cork and drop

in a solid particle of alum, however infinitesimal. Suddenly, the

liquid thickens into a solid lump and gives off heat. What has

happened? This: crystallization has set in at the first contact of

the particle of alum, the center of attraction; next, it has spread

bit by bit, each solidified particle producing the solidification

of those around. The impulse comes from an atom; the mass impelled

is boundless. The very small has revolutionized the immense.



Of course, in the comparison between these two instances and the

effects of my injections, the reader must see no more than a figure

of speech, which, without explaining anything, tries to throw a

glimmer of light upon it. The long procession of card friars is

knocked down by the mere touch of the little finger to the first;

the voluminous solution of alum suddenly turns solid under the

influence of an invisible particle. In the same way, the victims

of my operations succumb, thrown into convulsions by a tiny drop of

insignificant size and harmless appearance.



Then what is there in that terrible liquid? First of all, there is

water, inactive in itself and simply a vehicle of the active agent.

If a proof were needed of its innocuousness, here is one: I inject

into the thigh of any one of the sacred beetle's six legs a drop of

pure water larger than that of the fatal inoculations. As soon as

he is released, he makes off and trots about as nimbly as usual.

He is quite firm on his legs. When put back to his pellet, he

rolls it with the same zeal as before the experiment. My injection

of water makes no difference to him.



What else is there in the mixture in my watch glasses? There is

the disintegrated matter of the corpse, especially shreds of dried

muscles. Do these substances yield certain soluble elements to

water? Or are they simply reduced to a fine dust in the crushing?

I will not decide this question, nor is it really of importance.

The fact remains that the poison proceeds from those substances and

from them alone. Animal matter, therefore, which has ceased to

live is an agent of destruction within the organism. The dead cell

kills the living cell; in the delicate statics of life, it is the

grain of sand which, refusing its support, entails the collapse of

the whole edifice.



In this connection, we may recall those dreadful dissecting room

accidents. Through awkwardness, a student of anatomy pricks

himself with his scalpel in the course of his work; or else, by

inadvertence, he has an insignificant scratch on his hand. A cut

which one would hardly notice, produced by the point of a pocket

knife, a scratch of no account, from a thorn or otherwise, now

becomes a mortal wound, if powerful antiseptics do not speedily

remedy the ill. The scalpel is soiled by its contact with the

flesh of the corpse; so are the hands. That is quite enough. The

virus of corruption is introduced; and, if not treated in time, the

wound proves fatal. The dead has killed the living. This also

reminds us of the so-called carbuncle flies, the lancet of whose

mouth parts, contaminated with the sanies of corpses, produces such

terrible accidents.



My dealings as against insects are, when all is said, nothing but

dissecting room wounds and carbuncle flies' stings. In addition to

the gangrene that soon impairs and blackens the tissues, I obtain

convulsions similar to those produced by the scorpion's sting. In

its convulsive effects, the venomous fluid emitted by the sting

bears a close resemblance to the muscular infusions with which I

fill my injector. We are entitled, therefore, to ask ourselves if

poisons, generally speaking, are not themselves a produce of

demolition, a casting of the organism perpetually renewed, waste

matter, in short, which, instead of being gradually expelled, is

stored for purposes of attack and defense. The animal, in that

case, would arm itself with its own refuse in the same way as it

sometimes builds itself a home with its intestinal recrement.

Nothing is wasted; life's detritus is used for self defense.



All things considered, my preparations are meat extracts. If I

replace the flesh of the insect by that of another animal, the ox,

for instance, shall I obtain the same results? Logic says yes; and

logic is right. I dilute with a few drops of water a little

Liebig's extract, that precious standby of the kitchen. I operate

with this fluid on six Cetoniae or rosechafers, four in the grub

stage, two in the adult stage. At first, the patients move about

as usual. Next day, the two Cetoniae are dead. The larvae resist

longer and do not die until the second day. All show the same

relaxed muscles, the same blackened flesh, signs of putrefaction.

It is probable, therefore, that, if injected into our own veins,

the same fluid would likewise prove fatal. What is excellent in

the digestive tubes would be appalling in the arteries. What is

food in one case is poison in the other.



A Liebig's extract of a different kind, the broth in which the

liquefier puddles, is of a virulence equal, if not superior, to

that of my products. All those operated upon, Capricorns, sacred

beetles, ground beetles, die in convulsions. This brings us back,

after a long way round, to our starting point, the maggot of the

flesh fly. Can the worm, constantly floundering in the sanies of a

carcass, be itself in danger of inoculation by that whereon it

grows fat? I dare not rely upon experiments conducted by myself:

my clumsy implements and my shaky hand make me fear that, with

subjects so small and delicate, I might inflict deep wounds which

of themselves would bring about death.



Fortunately, I have a collaborator of incomparable skill in the

parasitic Chalcidid. Let us apply to her. To introduce her germs,

she has perforated the maggot's paunch, has even done so several

times over. The holes are extremely small, but the poison all

around is excessively subtle and has thus been able, in certain

cases, to penetrate. Now what has happened? The pupae, all from

the same apparatus, are numerous. They can be divided into three

not very unequal classes, according to the results supplied. Some

give me the adult flesh fly, others the parasite. The rest, nearly

a third, give me nothing, neither this year nor next.



In the first two cases, things have taken their normal course: the

grub has developed into a fly, or else the parasite has devoured

the grub. In the third case, an accident has occurred. I open the

barren pupae. They are coated inside with a dark glaze, the

remains of the dead maggot converted into black rottenness. The

grub, therefore, has undergone inoculation by the virus through the

fine openings effected by the Chalcidid. The skin has had time to

harden into a shell; but it was too late, the tissues being already

infected.



There you see it: in its broth of putrefaction, the worm is exposed

to grave dangers. Now there is a need for maggots in this world,

for maggots many and voracious, to purge the soil as quickly as

possible of death's impurities. Linnaeus tells us that 'Tres

muscae consumunt cadaver equi aeque cito ac leo." [Three flies

consume the carcass of a horse as quickly as a lion could do it.]

There is no exaggeration about the statement. Yes, of a certainty,

the offspring of the flesh fly and the bluebottle are expeditious

workers. They swarm in a heap, always seeking, always snuffling

with their pointed mouths. In those tumultuous crowds, mutual

scratches would be inevitable if the worms, like the other flesh

eaters, possessed mandibles, jaws, clippers adapted for cutting,

tearing and chopping; and those scratches, poisoned by the dreadful

gruel lapping them, would all be fatal.



How are the worms protected in their horrible work yard? They do

not eat: they drink their fill; by means of a pepsin which they

disgorge, they first turn their foodstuffs into soup; they practice

a strange and exceptional art of feeding, wherein those dangerous

carving implements, the scalpels with their dissecting room perils,

are superfluous. Here ends, for the present, the little that I

know or suspect of the maggot, the sanitary inspector in the

service of the public health.





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