THE DWARFS

More Beetles by Jean-Henri Fabre, is part of the HackerNoon Books Series. You can jump to any chapter in this book here. THE DWARFS

CHAPTER XI. 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 millimetres1 instead of eighteen,2 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 millimetres3 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.4 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 millimetres5 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,6 no more. The insect would have measured twenty millimetres7 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.

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