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The wrapper of the egg is of a horny nature, as silk itself is. It will not take long to transform the one into the other. The grub therefore tackles the remains of its egg, and turns it into silk to carry with it on its first journeys.

If my surmise is well founded, there is reason to believe that, with a view to filling speedily

the silk-glands whereto they look for a supply of ropes, other caterpillars living on smooth and steeply slanting leaves also take as their first mouthful the membranous sack which is all that remains of the egg.

The whole of the platform of birthsacks which was the first campingground of the white butterfly's family is razed to the ground; naught remains but the round marks of the individual pieces that composed it. The structure of piles has disappeared; the prints left by the piles remain. The little caterpillars

are

now on the level of the leaf which shall henceforth feed them. They are a pale orange-yellow, with a sprinkling of white bristles. The head is a shiny black, and remarkably powerful; it already gives signs of the coming gluttony. The little animal measures scarcely two millimeters in length.

The troop begins its steadying work as soon as it comes into contact with its pasturage, the green cabbage-leaf. Here, there, in its immediate neighborhood, each grub emits from its spinning-glands short cables, so slender that it takes an attentive lens to catch a glimpse of them. This is enough to insure the equilibrium of the almost imponderable atom.

The vegetarian meal now begins. The grub's length promptly increases from two millimeters to four. Soon a molt takes place which alters its costume: its skin becomes speckled, on a pale yellow ground, with a number of black dots intermingled with white bristles. Three or four days of rest are necessary after the fatigues of breaking cover. When this is over, the hunger-fit starts that is to make a ruin of the cabbage in a few weeks.

To eat and digest, to accumulate reserves whence the butterfly will issue, that is the caterpillar's one and only business. The

the

Soon I found the whole crowd of caterpillars dispersed all over

neighboring walls. The

thrust of a ledge, the eaves formed by

a projecting bit of mortar, served them as thelter where the chrysalid molt took place

cabbage-caterpillar performs it with insatiable gluttony. Incessantly it browses, incessantly digests the supreme felicity of an animal which is little more than an intestine. There is never a distraction, unless it be certain seesaw movements which are particularly curious when several caterpillars are grazing side by side, abreast. Then at intervals all the heads in the row are briskly lifted and as briskly lowered, time after time, with an automatic precision worthy of a Prussian drill-ground. Whether signs of fear or signs of bliss, these are the only exercises which the gluttons allow themselves until the proper degree of plumpness is attained.

After a month's grazing, the voracious appetite of my caged herd is assuaged. The caterpillars climb the trellis-work in every direction, walk about anyhow, with their fore part raised and searching space. Here and there, as they pass, the swaying herd puts forth a thread. They wander restlessly, anxious to travel afar. The exodus now prevented by the trellised inclosure I once saw under excellent conditions. At the advent of cold weather I had placed a few cabbage-stalks, covered with caterpillars, in a small hothouse. Things hap

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lazy grubs, varying greatly in number from ten or twenty at the least to sometimes half a hundred. They are the offspring of the Microgaster.

On what do they feed? The lens makes conscientious inquiries; nowhere does it manage to show me the vermin attacking solid nourishment, fatty tissues, muscles, or other parts; nowhere do I see them bite, gnaw, or dissect. The following experiment will tell us more fully: I pour into a watchglass the crowds extracted from the hospitable paunches. I flood them with caterpillar's blood, obtained by simple pricks; I place the preparation under a glass bell-jar, in a moist atmosphere to prevent evaporation; I repeat the nourishing bath by means of fresh bleeding, and give them the stimulant which they would have gained from the living caterpillar. Thanks to these precautions, my my charges have all the appearance of excellent health; they drink and thrive. But this state of things cannot last long. Soon, ripe for the transformation, my worms leave the dining-room of the watch-glass, as they would have left the caterpillar's belly; they come to the ground to try to weave their tiny cocoons. They fail in the attempt, and perish. They have missed a suitable support; that is to say, the silky carpet provided by the dying caterpillar. No matter; I have seen enough to convince me. The larvæ of the Microgaster do not eat in the strict sense of the word. They live on soup; and that soup is the caterpillar's blood.

[graphic]

The Microgaster lays her eggs within the caterpillar's, and her young are nourished during the larval state on caterpillar's blood, until in May a swarm of pygmies issues forth, ready to get to business in the cabbage-beds

Examine the parasites closely and you will see that their diet is bound to be a liquid one. They are little white grubs, neatly segmented, with a pointed fore part, splashed with tiny black marks, as though the atom had been slaking its thirst in a drop of ink. It moves its hind quarters slowly, without shifting its position. I place it under the microscope. The mouth is a pore, devoid of any apparatus for disintegration-work; it has no fangs, no horny nippers, no mandibles; its attack is just a kiss. It does not chew, it sucks, it takes discreet sips at the moisture all around it.

The fact that it refrains entirely from biting is confirmed by my autopsy of the

stricken caterpillars. In the patient's belly, notwithstanding the number of nurslings which hardly leave room for the nurse's entrails, everything is in perfect order; nowhere do we see a trace of mutilation. Nor does aught on the outside betray any havoc within. The exploited caterpillars graze and move about peacefully, giving no sign of pain. It is impossible for me to distinguish them from the unscathed ones in respect of appetite and untroubled digestion.

When the time approaches to weave the carpet for the support of the chrysalis, an appearance of emaciation at last points to the evil that is at their vitals. They spin, nevertheless. They are stoics who do not forget their duty in the hour of death. At last they expire, quite softly, not of any wounds, but of anemia, even as a lamp goes out when the oil comes to an end. And it has to be. The living caterpillar, capable of feeding itself and forming blood, is a necessity for the welfare of the worms; it

has to last about a month, until the Microgaster's offspring have achieved their full growth. The two calendars synchronize in a remarkable way. When the caterpillar leaves off eating and makes its preparations for the metamorphosis, the parasites are ripe for the exodus. The bottle dries up when the drinkers cease to need it; but until that moment it must remain more or less well filled, although becoming limper daily. It is important, therefore, that the caterpillar's existence be not endangered by wounds which, even though very tiny, would stop the working of the blood-fountains. With this intent, the drainers of the bottle are, in a manner of speaking, muzzled; they have for a mouth a pore that sucks without bruising.

The dying caterpillar continues to lay the silk of its carpet with a slow oscillation of the head. The moment now comes for the parasites to emerge. This happens in June, and generally at nightfall. A breach is made on the ventral surface, or else on the sides, never on the back; one breach only, contrived at a point of minor resistance, at the junction of two segments; for it is bound to be a toilsome business in the absence of a set of filing-tools. Perhaps the worms take one another's places at the point attacked, and come by turns to work at it with a kiss.

In one short spell the whole tribe issues through this single opening, and is soon wriggling about, perched on the surface of the caterpillar. The lens cannot perceive the hole, which closes on the instant. There is not even a hemorrhage; the bottle has been drained too thoroughly. You must press it between your fingers to squeeze out a few drops of moisture, and thus discover the spot of exit.

Around the caterpillar, which is not always quite dead and which sometimes even goes on weaving its carpet a moment longer, the vermin at once begin to work upon their cocoons. The straw-colored thread, drawn from the silk-glands by a backward jerk of the head, is first fixed to the white network of the caterpillar, and then produces adjacent warp-beams, so that by mutual entanglements the individual rks are welded together, and form

ation in which each of the wn cabin. For the moment,

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these frames rest upon those adjoining, and, mixing up their threads, become a common edifice wherein each grub contrives its own shelter. Here at last the real cocoon is spun, a pretty little piece of closely woven work.

In my rearing-jars, I obtain as many groups of those tiny shells as my future experiments can wish for. Three-fourths of the caterpillars have supplied me with them, so ruthless has been the toll of the spring births. I lodge these groups one by one in separate glass tubes, thus forming a collection which I can draw upon at will, while in view of my experiments, I keep under observation the whole swarm produced by one caterpillar.

The

The adult Microgaster appears a fortnight later, in the middle of June. There are fifty in the first tube examined. riotous multitude is in the full enjoyment of the pairing season, for the two sexes always figure among the guests of any one caterpillar. What animation! What an orgy of love! The carnival of those pygmies bewilders the observer and makes his head swim.

Most of the females, desirous of liberty, plunge down to the waist between the glass of the tube and the plug of cotton-wool that closes the end turned to the light; but the lower halves remain free, and form a circular gallery before which the males take turns. The turbulent wedding lasts all the morning, and begins afresh next day, a mighty throng of couples embracing, separating, and embracing once more.

There is every reason to believe that in gardens the mated ones, finding themselves in isolated couples, would keep quieter. Here in the tube things degenerate into a riot because the assembly is too numerous for the narrow space.

What is lacking to complete their happiness? Apparently, a little food, a few sugary mouthfuls extracted from the flowers. I serve up some provisions in the tubes; not drops of honey, in which the puny creatures would get stuck, but little strips of paper spread with that dainty. They come to them, take their stand on them, and refresh themselves. The fare appears to agree with them. With this diet, renewed as the strips dry up, I can keep them in very good condition until the end of my inquisition.

We will therefore place a new receptacle, jar or test-tube, on the table, pointing the closed end toward the sunlight. At its

[graphic]

In vain do we weigh suns and planets; our supremacy, which fathoms the universe, cannot prevent a wretched worm from levying its toll on our delicious fruit. We make ourselves at home in a cabbage bed the cone of the white butterfly make themselves at home there, too, for every creature has its claims on life

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