THE DWARFS
A Provençal proverb says:
“Chasque toupin trobo sa cubercello;
Chasque badan, sa badarello.”
It is true; every pot finds its lid, every Jack his Jill. The
hunchbacked, the blind, the bandy-legged, the physically or morally
deformed: one and all have their attractions which render them
acceptable in certain eyes.
Insects too, no less than men and stew-pans, always find their natural
complement, though it mate the faultless with the faulty. Of this
Minotaurus Typhœus furnishes a splendid example. The hazards of
excavation present me with a curious couple, keeping house at the
bottom of a burrow. The female calls for no special remark: she is just
a handsome matron. But the male! What a sorry creature, what an
abortion! The middle point of his trident is reduced to a mere spiked
granule; those at the side come just level with the eyes, whereas in
normal subjects they reach the extreme point of the head. I measure the
little beggar. His length is twelve millimetres [72] instead of
eighteen, [73] the ordinary size. According to these figures, the dwarf
is barely a quarter of the usual bulk.
In an earlier chapter of the present volume, I mentioned a magnificent
male Minotaur who was obstinately refused by the consort whom my
experiments had given him. The handsome horn-bearer did not leave the
burrow; the other, despite my frequent interventions to restore harmony
in the household, deserted her home nightly and sought to set up house
elsewhere. I had to give her another partner; the one that I had thrust
upon her did not suit her. If the male endowed with a generous stature
and trident is often refused, how did the miserable specimen under
consideration win the affections of his powerful mate? The unequal
associations are doubtless to be explained among the Dung-beetles as
among ourselves: love is blind.
Would this ill-assorted pair have bred? And would one part of the
family have inherited the noble dimensions of the mother and the other
the stunted dimensions of the father? Not possessing, at the moment, a
suitable apparatus, that is to say, a tall column of earth held between
four planks, I lodged my Beetles in the longest test-tube among my
entomological glass-ware, with moist sand and victuals at their
disposal.
At first, all went according to rule, the mother digging and the father
clearing away the rubbish. A few droppings were stored; then, on
reaching the bottom of the test-tube, the couple pined away and died.
The layer of sand was not deep enough. Before piling the food-sausage
on top of an egg, the pair needed a shaft at least forty inches in
depth, whereas they had only some eighteen inches to dig in.
This failure did not put an end to my list of questions. Where did that
pigmy spring from? Was he the outcome of a special predisposition,
transmitted by heredity? Or was he descended from another dwarf, who
himself proceeded from a similar abortion? Was his deficiency merely an
accident, which had nothing to do with heredity, an individual
littleness not transmissible from father to son? I incline to the
theory of an accident. But what sort of accident? I can think of only
one liable to diminish the size without injuring the type: I mean, a
lack of sufficient food.
We argue thus: animals virtually take shape in a mould whose capacity
may be extended in proportion to the amount of molten substance which
the crucible pours into it. If this mould receives only the strictly
necessary amount, the result is a dwarf. Anything beneath this minimum
means death by starvation; anything above it, in doses which increase
but are soon limited, means a prosperous life and a normal or slightly
larger size. The bulk is decided by plus or minus quantities of food.
If logic be not a vain delusion, it is therefore possible to obtain
dwarfs at will. All that we need do is to diminish the provisions to
the lowest limits compatible with the maintenance of life. On the other
hand, we cannot hope to make giants by increasing the ration, for a
moment comes when the stomach refuses any excess of food. Natural
necessities may be likened to a series of rungs of which the one at the
top cannot be passed, while it is quite practicable to stand higher or
lower on those near the bottom.
First of all we must discover the regular ration. The majority of
insects have none. The larva grows up amidst an indeterminate supply of
victuals; it eats as it pleases and as much as it pleases, with no
other check than its appetite. Others, those most richly endowed in
maternal qualities such as the Dung-beetles and the Bees and Wasps,
prepare definite rations of preserved food, neither too large nor too
small. The Bee stores up in receptacles of clay, cement, resin, cotton
or leaf-cuttings just the right amount of honey for a larva’s welfare;
and, as she knows the sex of the future insects, she puts a little more
at the service of the grubs that are to become females and will be
slightly larger and a little less at the service of the grubs that are
to become males and therefore will be smaller. In like manner, the
Hunting Wasps dole out their game according to the sex of the
nurslings.
It is now a long time since I did my utmost to upset the mother’s wise
previsions by taking food from the wealthy grubs to increase the store
of the poor. In this way I obtained some slight modifications of size,
to which the terms giant and dwarf could not, however, be applied;
still less did I succeed in changing the sex, whose determination does
not in any way depend upon the quantity of food supplied. The Bees and
Wasps are not suited to my present purpose. Their grubs are too
delicately constituted. What I want is sturdy stomachs capable of
enduring severe ordeals. I shall find them in the Dung-beetles, notably
in the Sacred Beetle, whose natural portliness will facilitate our
appreciation of any change of bulk.
The big pill-roller calculates the food of her larvæ precisely: each
grub has its loaf, kneaded into the shape of a pear. All these loaves
are not strictly equal; some are larger and some smaller, but the
difference is only minute. Perhaps these slight inequalities are
connected with the sex of the nurslings, as among the Bees and Wasps;
the females would receive the larger and the males the smaller rations.
I did not take any steps to verify this theory. No matter: the fact
remains that the Sacred Beetle’s pear is, in the mother’s opinion, a
convenient individual ration. As for me, I can, if I please, alter the
size of the loaf, increasing or decreasing it at will. Let us first
consider the decrease.
In May, I procure four recent pears, containing the egg in the chamber
of the terminal nipple. By making an equatorial section, I cut off the
hinder half, in the shape of a large spherical cap; the other half,
surmounted by its neck, I retain; and I place the four egg-bearing
portions in as many small jars, in which there is no danger of either
desiccation or excessive damp.
With these provisions decreased by half, development takes place as
usual; then two of the grubs die, apparently the victims of defective
hygiene: my jars are not equal to the burrows, with their pleasant
moisture. The two others are still in good condition, ever ready to
plug with dung the window which I cut through the wall of the cell when
I wish to inspect them. At the end of the active period, I find them
remarkably small in comparison with those of their fellows who have
been left in possession of the whole pear. The effect of insufficient
food is already manifest. What will it be in the perfect insect?
In September there emerge from the shells adults such as my hunts in
the meadows never yielded, dwarfs, hardly larger than a thumbnail, but
correctly shaped in every other respect.
Let me quote some exact figures. Each of them measures nineteen
millimetres [74] from the edge of the clypeus to the tip of the
abdomen. The smallest specimen in my boxes, as the freedom of the
fields made him, measures twenty-six. [75] The products of my
experiments, fed upon half rations, are therefore only half the bulk of
the normal Beetle chosen from among the smallest. This is also
approximately the ratio between the full and the reduced diet. The
extensible mould of the organism has reproduced the proportion of the
substance at its disposal.
My intervention has just created dwarfs; treatment by starvation has
given me abortions. I am not excessively proud of it, though I am glad
to have learned by experiment that dwarfishness, at all events in the
insects, is not a matter of predisposition and heredity but a mere
accident caused by deficient nourishment.
What then had happened to the little Minotaur who suggested these
experiments in starvation? Assuredly a deficiency of food. Though
expert in the art of rationing, the mother was unable to complete the
sausage over the egg, perhaps because the materials were lacking, or
because some inopportune incident interrupted her work; and the grub,
scantily fed, though strong enough to withstand a not too rigorous
diet, was unable to acquire the wherewithal to provide the adult with
the amount of substance needed for the normal size. This seems to be
the whole secret of the tiny Minotaur. He was a child of poverty.
While privation reduces the size, it does not follow that unlimited
abundance is able to increase it very notably. In vain do I provide the
grubs of the Sacred Beetle with an extra allowance of food that doubles
or trebles the ration supplied by the mother. My boarders do not attain
a growth worth mentioning. As they leave the maternal pears, so do they
leave the plentiful messes which my spatula has mixed for them. And
this must be so: the appetite has its limits, which, once reached,
leave the consumer indifferent to the luxuries of the table. It is not
in our power to make giants by means of an excess of food. When the
grub has gorged to the required degree, it ceases to eat.
There are nevertheless giants among the Sacred Beetles. I have some
that came from Ajaccio and Algeria and measure thirty-four millimetres
[76] in length. By comparing this figure with those already given, we
see that, if the size of the dwarfs obtained by fasting is represented
by the figure 1, that of the Sacred Beetle of the Sérignan district is
expressed by 2 and that of the Corsican and African Beetles by 5.
To produce these latter, these giants, it is evident that a more
generous diet is needed. Whence comes this increase of appetite? We
whet ours with condiments. The insect may well have condiments of its
own, for instance, as regards the Sacred Beetle, the pepper of the
sea-breezes and the mustard of a generous sun. Such, it seems to me,
are the causes which augment the dimensions of the African Scarabæus
and reduce those of his Sérignan kinsman. As I have not these two
appetizers, the sea and the sun, at my disposal, I give up the idea of
making giants by an excess of victuals.
Let us now try the larvæ which, not being rationed by the mother, have
unlimited abundance at their disposal. Among them are the larvæ of
Cetonia floricola, Herbst, living in heaps of decomposing leaves. I
shall certainly never obtain giants from these by resorting to the
artifice of a copious diet! In a corner of my garden they swarm in a
heap of rotten leaves, where they find the wherewithal to satisfy their
gluttonous appetites to the full, without having to hunt for it; and
yet I never find an adult whose dimensions are ever so little
exaggerated. To make him exceed the usual proportions it is probable
that better climatic conditions are necessary, as in the case of the
Sacred Beetle, conditions of which I know nothing and which, moreover,
I should be unable to realize. Only one experiment lies within my
power, that of starvation.
At the beginning of April, I take three batches of larvæ of Cetonia
floricola chosen from among those most fully developed and therefore
liable to undergo their transformation during the course of the summer.
At this April season the great hunger sets in which doubles the size of
the grub and amasses the reserves needed for the elaboration of the
adult. The three batches are installed in large tin boxes, carefully
closed, in which there is no danger of too rapid desiccation.
The first batch consists of twelve grubs, which are given an abundance
of food, renewed as the need arises. My prisoners could not be better
off in the heap of leaf-mould, their favourite resort.
Side by side with this gastric paradise, a second tin, a very inferno
of starvation, receives a dozen larvæ kept absolutely without food. It
is furnished—as, for that matter, are the others—with a litter of
droppings, enabling the famished creatures to wander about or bury
themselves at will.
Lastly, the third batch, likewise twelve in number, receives from time
to time a scanty pinch of rotten leaves, enough at most to beguile
their mandibles for a moment.
Three or four months go by and, when the torrid heats of July have
come, the first tin gives me the perfect insect. Its development has
been accomplished without a check: the twelve grubs are succeeded by
twelve magnificent Cetoniæ, resembling at all points those who sip and
slumber in the roses when the spring comes. This result convinces me
that the defects attaching to rearing in confinement have nothing to do
with what remains to be told.
The second tin, in which strict abstinence is enforced, provides me
with two chrysalids, whose diminished size indicates the presence of
dwarfs. I wait until the middle of September to open these caskets,
which remained closed when those in the first tin burst, two months
ago. Their persistent refusal to split open is explained: each of them
contains nothing but a dead larva. Absolute starvation was too much for
the grubs’ endurance. Of the twelve kept without food, ten shrivelled
up and eventually died; only two managed to wrap themselves in a shell,
by gluing the droppings round about in the usual way. This was their
last effort. The two grubs, incapable of performing the consummate
labour of the nymphosis, perished in their turn.
Lastly, in the third tin, where victuals were very sparingly provided,
eleven grubs out of twelve died, worn out with privation. One only has
enclosed itself in a cocoon, which is correctly made but very much
reduced in size. If there is a living insect within, it can only be a
dwarf. In the middle of September, I open the cabin myself, for there
is nothing yet, at this late period, to announce an impending natural
fracture.
The contents fill me with delight. They consist of a Cetonia, alive and
kicking, all brilliant with metallic gleams and streaked with a few
white stripes, like those of the species who have developed freely in
the great heap of earth-mould. The shape and costume are not altered in
any respect. As for size, that is another matter. I have before my eyes
a pigmy, a little gem more exquisite than any collector ever found on
the blossoming hawthorns. From the edge of the clypeus to the tips of
the wing-cases this creature of my artificial devices measures thirteen
millimetres, [77] no more. The insect would have measured twenty
millimetres [78] if the grub had been properly fed, far away from my
famine-stricken tins. From these figures we deduce that the dwarf’s
bulk is about one-fourth of what it would have become normally, without
my interference.
Of the twenty-four larvæ subjected, during three or four months, some
to an absolute fast and others to a diet of meagre mouthfuls
administered at long intervals, one only reached the adult form. The
bad effects of abstinence are far-reaching and the pigmy still feels
them. Though the season when the caskets should have split had long
gone by, he had made no attempt to free himself. Perhaps he had not the
necessary strength. I myself had to break open the cell.
Now that he is free and revelling in the light, he kicks and struggles
and starts running, if I tease him at all; but he prefers to rest. One
would think that he was overwhelmed by an insurmountable lassitude. I
know how gluttonously the Cetoniæ attack fruit at this warm season,
gorging themselves upon the sweet pulp. I give my dwarf a piece of
juicy fig. He does not touch it, preferring to doze. Is it not yet time
for him to eat, after his forcible liberation? Was the recluse intended
to spend the winter in his shell before tasting the joys but also
risking the dangers of the outer world? It may be so.
At any rate this curious little creature, the small Cetonia, reduced to
one-fourth of the regulation size, repeats what the Sacred Beetle but
now taught us in a less conclusive fashion, that, among the insects and
very likely elsewhere, dwarfishness is the result of incomplete
nutrition and not in any way the effect of predisposition.
Let us suppose an impossible case, or at least one extremely difficult
to realize; let us imagine that, having obtained by starvation a few
couples of Cetoniæ, we were able to keep them alive under favourable
conditions. Would they found a family? And what would their offspring
be like? The insect, in all probability, would not reply to our
question, even though entreated by long perseverance; but the plant
answers us readily.
On the paths in my two acres of pebbles, at spots where a little
moisture lingers, there grows in April a familiar plant, the whitlow
grass (Draba verna, Lin.). There is but little nourishment in this
ungrateful trodden soil, hard with gravel, and the whitlow grass may be
regarded as the equivalent of my famished Cetoniæ. From a flat pattern
of sickly leaves rises a single stem, no thicker than a hair, barely an
inch in height and with few ramifications or none, which nevertheless
ripens its silicles, often reduced to one alone. Here, in short, I have
a little garden of dwarf plants, the children of dearth. My experiments
in starvation were far from obtaining such results with the Sacred
Beetle and the Cetonia.
I collect the seeds from the heads of the sickliest of these plants and
sow them in good soil. Next spring, the dwarfishness disappears at
once; the direct descendants of the abortive plants produce ample
radiating patterns, multiple stalks reaching to a height of four inches
or more and numerous ramifications, rich in silicles. The normal
condition has returned.
If they had had enough energy to procreate their species, my dwarf
insects, resulting from my artifices or from a casual concourse of
enfeebling circumstances, would do as much. They would repeat what the
whitlow grass has told us: that dwarfishness is an accident which
heredity does not hand down, any more than it hands down knock-knees,
or bow-legs, or the hunchback’s hump or the stump of the one-armed
cripple.