The army ants flowed over the ground like a surging, monstrous, inky tide. Their vanguard reached the river and recoiled. Burl was perhaps five miles away when they changed their course. The change was made without confusion, the leaders somehow communicating the altered line of march to those behind them.

Back on Earth, scientists had gravely debated the question of how ants conveyed ideas to each other. Honeybees, it was said, performed elaborate ritual dances to exchange information. Ants, it had been observed, had something less eccentric. A single ant, finding a bit of booty too big for it to manage alone, would return to its city to secure the help of others. From that fact men had deduced that a language of gestures made with crossed antennae must exist.

Burl had no theories. He merely knew facts, but he did know that ants could and did pass information to one another. Now, however, he moved cautiously along toward the sleeping-place of his tribe in complete ignorance of the black blanket of living creatures spreading over the ground behind him.

A million tragedies marked the progress of the insect army. There was a tiny colony of mining bees, their habits unchanged despite their greater size, here on the forgotten planet. A single mother, four feet long, had dug a huge gallery with some ten offshooting cells, in which she had laid her eggs and fed her grubs with hard-gathered pollen. The grubs had waxed fat and large, become bees, and laid eggs in their turn within the same gallery their mother had dug out for them.

Ten bulky insects now foraged busily to feed their grubs within the ancestral home, while the founder of the colony had grown draggled and wingless with the passing of time. Unable to bring in food, herself, the old bee became the guardian of the hive. She closed the opening with her head, making a living barrier within the entrance. She withdrew only to grant admission or exit to the duly authorized members,—her daughters.

The ancient concierge of the underground dwelling was at her post when the wave of army ants swept over. Tiny, evil-smelling feet trampled upon her and she emerged to fight with mandible and sting for the sanctity of her brood. Within moments she was a shaggy mass of biting ants. They rent and tore at her chitinous armor. But she fought on madly, sounding a buzzing alarm to the colonists yet within.

They came out, fighting as they came: ten huge bees, each four to five feet long and fighting with legs and jaws, with wing and mandible, and with all the ferocity of so many tigers. But the small ants covered them, snapping at their multiple eyes, biting at the tender joints in their armour,—and sometimes releasing the larger prey to leap upon an injured comrade, wounded by the monster they battled together.

Such a fight, however, could have but one end. Struggle as the bees might, they were powerless against their un-numbered assailants. They were being devoured even as they fought. And before the last of the ten was down the underground gallery had been gutted both of the stored food brought by the adult defenders and the last morsels of what had been young grubs, too unformed to do more than twitch helplessly, inoffensively, as they were torn to shreds.

When the army ants went on there were merely an empty tunnel and a few fragments of tough armor, unappetizing even to the ants.

Burl heard them as he meditatively inspected the scene of a tragedy of not long before. The rent and scraped fragments of a great beetle's shiny casing lay upon the ground. A greater beetle had come upon the first and slain him. Burl regarded the remains of the meal.

Three or four minims, little ants barely six inches long, foraged industriously among the bits. A new ant-city was to be formed and the queen lay hidden half a mile away. These were the first hatchlings. They would feed their younger kindred until they grew large enough to take over the great work of the ant-city. Burl ignored the minims. He searched for a weapon of some sort. Behind him the clicking, high-pitched roar of the horde of army ants increased in volume.

He turned away disgustedly. The best thing he could find in the way of a weapon was a fiercely-toothed hind-leg. When he picked it up an angry whine rose from the ground. One of the minims had been struggling to detach a morsel of flesh from the leg-joint. Burl had snatched the tidbit from him.

The little creature was surely no more than half a foot long, but it advanced angrily upon Burl, shrilling a challenge. He struck with the beetle's leg and crushed the ant. Two of the other minims appeared, attracted by the noise the first had made. They discovered the crushed body of their fellow, unceremoniously dismembered it, and bore it away in triumph.

Burl went on, swinging the toothed limb in his hand. The sound behind him became a distant whispering, high-pitched and growing steadily nearer. The army ants swept into a mushroom forest and the yellow, umbrella-like growths soon swarmed with the black creatures.

A great bluebottle fly, shining with a metallic lustre, stood beneath a mushroom on the ground. The mushroom was infected with maggots which exuded a solvent pepsin that liquefied the firm white meat. They swam ecstatically in the liquid gruel, some of which dripped and dripped to the ground. The bluebottle was sipping the dark-colored liquid through its long proboscis, quivering with delight as it fed on the noisomeness.

Burl drew near and struck. The fly collapsed in a quivering heap. Burl stood over it for an instant and pondered.

The army ants were nearer, now. They swarmed down into a tiny valley, rushing into and through a little brook over which Burl had leaped. Since ants can remain underwater for a long time without drowning, the small stream was not even dangerous. Its current did sweep some of them away. A great many of them, however, clung together until they chocked its flow by the mass of their bodies, the main force marching across the bridge they constituted.

The ants reached a place about a quarter of a mile to the left of Burl's line of march, perhaps a mile from the spot where he stood over the dead bluebottle. There was an expanse of some acres in which the giant, rank cabbages had so far succeeded in their competition with the world of fungi. The pale, cross-shaped flowers of the cabbages formed food for many bees. The leaves fed numberless grubs and worms. Under the fallen-away dead foliage—single leaves were twenty feet across at their largest—crickets hid and fed.

The ant-army flowed into this space, devouring every living thing it encountered. A terrible din arose. The crickets hurtled away in erratic leapings. They shot aimlessly in any direction. More than half of them landed blindly in the carpeting of clicking black bodies which were the ants from whose vanguard they had fled. Their blind flight had no effect save to give different individuals the opportunity to seize them as they fell and instantly begin to devour them. As they were torn to fragments, horrible screamings reached Burl's ears.

A single such cry of agony would not have attracted Burl's attention. He lived in a world of nightmare horror. But a chorus of creatures in torment made him look up. This was no minor horror. Something wholesale was in progress. He jerked his head about to see what it was.

A wild stretch of sickly yellow fungus was interspersed here and there with a squat toadstool, or a splash of vivid color where one of the many rusts had found a foothold. To the left a group of branched fungoids clustered in silent mockery of a true forest. Burl saw the faded green of the cabbages.

With the sun never shining on the huge leaves save through the cloud-bank overhead, the cabbages were not vivid. There were even some mouldy yeasts of a brighter green and slime much more luridly tinted. Even so, the cabbages were the largest form of true vegetation Burl had ever seen. The nodding white cruciform flowers stood out plainly against the yellowish, pallid green of the leaves. But as Burl gazed at them, the green slowly became black.

Three great grubs, in lazy contentment, were eating ceaselessly of the cabbages on which they rested. Suddenly first one and then another began to jerk spasmodically. Burl saw that around each of them a rim of black had formed. Then black motes milled all over them.

The grubs became black—covered with biting, devouring ants. The cabbages became black. The frenzied contortions of the grubs told of the agonies they underwent as they were literally devoured alive. And then Burl saw a black wave appear at the nearer edge of the stretch of yellow fungus. A glistening, living flood flowed forward over the ground with a roar of clickings and a persistent overtone of shrill stridulations.

Burl's scalp crawled. He knew what this meant. And he did not pause to think. With a gasp of pure panic he turned and fled, all intellectual preoccupations forgotten.

The black tide came on after him.

He flung away the edible mushroom he had carried under his arm. Somehow, though, he clung to the sharp-toothed club as he darted between tangled masses of fungus, ignoring now the dangers that ordinarily called for vast caution.

Huge flies appeared. They buzzed about him loudly. Once he was struck on the shoulder by one of them—at least as large as his hand—and his skin torn by its swiftly vibrating wings.

He brushed it away and sped on. But the oil with which he was partly covered had turned rancid, now, and the fetid odor attracted them. There were half a dozen—then a dozen creatures the size of pheasants, droning and booming as they kept pace with his wild flight.

A weight pressed onto his head. It doubled. Two of the disgusting creatures had settled upon his oily hair to sip the stuff through their hairy feeding-tubes. Burl shook them off with his hand and raced madly on, his ears attuned to the sounds of the ants behind him.

That clicking roar continued, but in Burl's ears it was almost drowned out by the noise made by the halo of flies accompanying him. Their buzzing had deepened in pitch with the increase in size of all their race. It was now the note close to the deepest bass tone of an organ. Yet flies—though greatly enlarged on the forgotten planet—had not become magnified as much as some of the other creatures. There were no great heaps of putrid matter for them to lay their eggs in. The ants were busy scavengers, carting away the debris of tragedies in the insect world long before it could acquire the gamey flavor beloved of fly-maggots. Only in isolated spots were the flies really numerous. In such places they clustered in clouds.

Such a cloud began to form about Burl as he fled. It seemed as though a miniature whirlwind kept pace with him—a whirlwind composed of furry, revolting bodies and multi-faceted eyes. Fleeing, Burl had to swing his club before him to clear the way. Almost every stroke was interrupted by an impact against some thinly-armored body which collapsed with the spurting of reddish liquid.

Then an anguish as of red-hot iron struck upon Burl's back. One of the stinging flies had thrust its sharp-tipped proboscis into his flesh to suck the blood. Burl uttered a cry and ran full-tilt into the stalk of a blackened, draggled toadstool.

There was a curious crackling as of wet punk. The toadstool collapsed upon itself with a strange splashing sound. A great many creatures had laid their eggs in it, until now it was a seething mass of corruption and ill-smelling liquid.

When the toadstool crashed to the ground, it crumbled into a dozen pieces, spattering the earth for yards all about with stinking stuff in which tiny, headless maggots writhed convulsively.

The deep-toned buzzing of the flies took on a note of solemn satisfaction. They settled down upon this feast. Burl staggered to his feet and darted off again. Now he was nothing but a minor attraction to the flies, only three or four bothering to come after him. The others settled by the edges of the splashing fluid, quickly absorbed in an ecstasy of feasting. The few still hovering about his head, Burl killed,—but he did not have to smash them all. The remaining few descended to feast on their fallen comrades twitching feebly at his feet.

He ran on and passed beneath the wide-spreading leaves of an isolated giant cabbage. A great grasshopper crouched on the ground, its tremendous radially-opening jaws crunching the rank vegetation. Half a dozen great worms ate steadily of the leaves that supported them. One had swung itself beneath an overhanging leaf—which would have thatched houses for men—and was placidly anchoring itself for the spinning of a cocoon in which to sleep the sleep of metamorphosis.

A mile away, the great black tide of army ants advanced relentlessly. The great cabbage, the huge grasshopper, and all the stupid caterpillars on the leaves would presently be covered with small, black demons. The cocoon would never be spun. The caterpillars would be torn into thousands of furry fragments and devoured. The grasshopper would strike out with his terrific, unguided strength, crushing its assailants with blows of its great hind-legs and powerful jaws. But it would die, making terrible sounds of torments as the ants consumed it piecemeal.

The sound of the ants' advance overwhelmed all other noises now. Burl ran madly, his breath coming in great gasps, his eyes wide with panic. Alone of the world about him, he knew the danger that followed him. The insects he passed went about their business with that terrifying, abstracted efficiency found only in the insect world.

Burl's heart pounded madly from his running. The breath whistled in his nostrils—and behind him the flood of army ants kept pace. They came upon the feasting flies. Some took to the air and escaped. Others were too absorbed in their delicious meal. The twitching maggots, stranded by the scattering of their soupy broth, were torn to shreds and eaten. The flies who were seized vanished into tiny maws. And the serried ranks of ants moved on.

Burl could hear nothing else, now, but the clickings of their limbs and the stridulating challenges and cross-challenges they uttered. Now and then another sound pierced the noises made by the ants themselves: a cricket, perhaps, seized and dying, uttering deep-bass cries of agony.

Before the horde there was a busy world which teemed with life. Butterflies floated overhead on lazy wings; grubs waxed fat and huge; crickets feasted; great spiders sat quietly in their lairs, waiting with implacable patience for prey to fall into the trap-doors and snares; great beetles lumbered through the mushroom forests, seeking food and making love in monstrous, tragic fashion.

Behind the wide front of the army ants was—chaos. Emptiness. Desolation. All life save that of the army ants was exterminated, though some bewildered flying creatures still fluttered helplessly over the silent landscape. Yet even behind the army ants little bands of stragglers from the horde marched busily here and there, seeking some trace of life that had been overlooked by the main body.

Burl put forth his last ounce of strength. His limbs trembled. His breathing was agony. Sweat stood out upon his forehead. He ran for his life with the desperation of one who knows that death is at his heels. He ran as if his continued existence among the million tragedies of the single day were the purpose for which the universe had been created.

There was redness in the west and in the cloud-bank overhead. To the east gray sky became a deeper gray—much deeper. It was not yet time for the creatures of the day to seek their hiding-places, nor for the night-insects to come forth. But in many secret spots there were vague and sleepy stirrings.

Heedless of the approaching darkness Burl sped over an open space a hundred yards across. A thicket of beautifully golden mushrooms barred his way. Danger lay there. He dogged aside and saw in the gray dusk a glistening sheet of white, barely a yard above the ground. It was the web of the morning-spider which, on Earth, was noted only in hedges and such places when the dew of earliest dawn exposed it as a patternless plate of diamond-dust. There were anchor-cables, of course, but no geometry. Tidy housewives—also on Earth—used to mop it out of corners as a filmy fabric of irritating gossamer. On the forgotten planet it was a net with strength and bird-lime qualities that increased day by day, as its spinner moved restlessly over the surface, always trailing sticky cord behind itself.

Burl had no choice but to avoid it, even though he lost ground to the ant-horde roaring behind him. And night was definitely on the way. It was inconceivable that a human should travel in the lowlands after dark. It literally could not be done over the normal nightmare terrain. Burl had not only to escape the army ants, but find a hiding-place quickly if he was to see tomorrow's light. But he could not think so far ahead, just now.

He blundered through a screen of puffballs that shot dusty powder toward the sky. Ahead, a range of strangely colored hills came into view—purple, green, black and gold—melting into each other and branching off, inextricably mingled. They rose to a height of perhaps sixty or seventy feet. A curious grayish haze had gathered above them. It seemed to be a layer of thin vapor, not like mist or fog, clinging to certain parts of the hills, rising slowly to coil and gather into an indefinitely thicker mass above the ridges.

The hills themselves were not geological features, but masses of fungus that had grown and cannibalized, piling up upon themselves to the thickness of carboniferous vegetation. Over the face of the hills grew every imaginable variety of yeast and mould and rust. They grew within and upon themselves, forming freakish conglomerations that piled up into a range of hills, stretching across the lunatic landscape for miles.

Burl blundered up the nearest slope. Sometimes the surface was a hard rind that held him up. Sometimes his feet sank—perhaps inches, perhaps to mid-leg. He scrambled frantically. Panting, gasping, staggering from the exhaustion of moving across the fungus quicksand, he made his way to the top of the first hill, plunged down into a little valley on the farther side, and up another slope. He left a clear trail behind him of disturbed and scurrying creatures that had inevitably found a home in the mass of living stuff. Small sinuous centipedes scuttled here and there, roused by his passage. At the bottom of his footprints writhed fat white worms. Beetles popped into view and vanished again....

A half mile across the range and Burl could go no farther. He stumbled and fell and lay there, gasping hoarsely. Overhead the gray sky had become a deep-red which was rapidly melting into that redness too deep to be seen except as black. But there was still some light from the west.

Burl sobbed for breath in a little hollow, his sharp-toothed club still clasped in his hands. Something huge, with wings like sails, soared in silhouette against the sunset. Burl lay motionless, breathing in great gasps, his limbs refusing to lift him.

The sound of the army ants continued. At last, above the crest of the last hillock he had surmounted, two tiny glistening antennae appeared, then the small, deadly shape of an army ant. The forerunner of its horde, it moved deliberately forward, waving its antennae ceaselessly. It made its way toward Burl, tiny clickings coming from its limbs.

A little wisp of vapor swirled toward the ant. It was the vapor that had gathered over the whole range of hills as a thin, low cloud. It enveloped the ant which seemed to be thrown into a strange convulsion, throwing itself about, legs moving aimlessly. If it had been an animal instead of an insect, it would have choked and gasped. But ants breathe through air-holes in their abdomens. It writhed helplessly on the spongy stuff across which it had been moving.

Burl was conscious of a strange sensation. His body felt remarkably warm. It felt hot. It was an unparalleled sensation, because Burl had no experience of fire or the heat of the sun. The only warmth he had ever known was when huddling together with his tribesmen in some hiding-place to avoid the damp chill of the night.

Then, the heat of their breath and flesh helped to combat discomfort. But this was a fiercer heat. It was intolerable. Burl moved his body with a tremendous effort and for a moment the fungus soil was cool beneath him. Then the sensation of hotness began again and increased until Burl's skin was reddened and inflamed.

The tenuous vapor, too, seemed to swirl his way. It made his lungs smart and his eyes water. He still breathed in painful gasps, but even that short period of rest had done him some good. But it was the heat that drove him to his feet again. He crawled painfully to the crest of the next hill. He looked back.

This was the highest hill he had come upon and he could see most of the purple range in the deep, deep dusk. Now he was more than halfway through the hills. He had barely a quarter-mile to go, northward. But east and west the range of purple hills was a ceaseless, undulating mass of lifts and hollows, of ridges and spurs of all imaginable colorings.

And at the tips of most of them were wisps of curling gray.

From his position he could see a long stretch of the hills not hidden by the surrounding darkness. Back along the way he had come, the army ants now swept up into the range of hills. Scouts and advance-guard parties scurried here and there. They stopped to devour the creatures inhabiting the surface layers. But the main body moved on inexorably.

The hills, though, were alive, not upheavals of the ground but festering heaps of insanely growing fungus, hollowed out in many places by tunnels, hiding-places, and lurking-places. These the ants invaded. They swept on, devouring everything....

Burl leaned heavily upon his club and watched dully. He could run no more. The army ants were spreading everywhere. They would reach him soon.

Far to the right, the vapor thickened. A thin column of smoke arose in the dim half-light. Burl did not know smoke, of course. He could not conceivably guess that deep down in the interior of the insanely growing hills, pressure had killed and oxidation had carbonized the once-living material. By oxidation the temperature down below had been raised. In the damp darkness of the bowels of the hills spontaneous combustion had begun.

The great mounds of tinderlike mushroom had begun to burn very slowly, quite unseen. There had been no flames because the hills' surface remained intact and there was no air to feed the burning. But when the army ants dug ferociously for fugitive small things, air was admitted to tunnels abandoned because of heat.

Then slow combustion speeded up. Smoulderings became flames. Sparks became coals. A dozen columns of fume-laden smoke rose into the heavens and gathered into a dense pall above the range of purple hills. And Burl apathetically watched the serried ranks of army ants march on toward the widening furnaces that awaited them.

They had recoiled from the river instinctively. But their ancestors had never known fire. In the Amazon basin, on Earth, there had never been forest fires. On the forgotten planet there had never been fires at all, unless the first forgotten colonists tried to make them. In any case the army ants had no instinctive terror of flame. They marched into the blazing openings that appeared in the hills. They snapped with their mandibles at the leaping flames, and sprang to grapple with the burning coals.

The blazing areas widened as the purple surface was consumed. Burl watched without comprehension—even without thankfulness. He stood breathing more and more easily until the glow from approaching flames reddened his skin and the acrid smoke made tears flow from his eyes. Then he retreated slowly, leaning on his club and often looking back.

Night had fallen, but yet it was light to the army ants. They marched on, shrilling their defiance. They poured devotedly—and ferociously—into the inferno of flame. At last there were only small groups of stragglers from the great ant-army scurrying here and there over the ground their comrades had stripped of all life. The bodies of the main army made a vast malodor, burning in the furnace of the hills.

There had been pain in that burning, agony such as no one would willing dwell upon. But it came of the insane courage of the ants, attacking the burning stuff with their horny jaws, rolling over and over with flaming lumps of charcoal clutched in their mandibles. Burl heard them shrilling their war-cry even as they died. Blinded, antennae singed off, legs shriveling, they yet went forward to attack their impossible enemy.

Burl made his way slowly over the hills. Twice he saw small bodies of the vanished army. They had passed between the widening furnaces and furiously devoured all that moved as they forged ahead. Once Burl was spied, and a shrill cry sounded, but he moved on and only a single ant rushed after him. Burl brought down his club and a writhing body remained to be eaten by its comrades when they came upon it.

And now the last faint traces of light had vanished in the west. There was no real brightness anywhere except the flames of the burning hills. The slow, slow nightly rain that dripped down all through the dark hours began. It made a pattering noise upon the unburnt part of the hills.

Burl found firm ground beneath his feet. He listened keenly for sounds of danger. Something rustled heavily in a thicket of toadstools a hundred feet away. There were sounds of preening, and of feet delicately placed here and there upon the ground. Then a great body took to the air with the throbbing beat of mighty wings.

A fierce down-current of air smote Burl, and he looked upward in time to glimpse the outline of a huge moth passing overhead. He turned to watch the line of its flight, and saw the fierce glow filling all the horizon. The hills burned brighter as the flames widened.

He crouched beneath a squat toadstool and waited for the dawn. The slow-dripping rain kept on, falling with irregular, drum-like beats upon the tough top of the toadstool.

He did not sleep. He was not properly hidden, and there was always danger in the dark. But this was not the darkness Burl was used to. The great fires grew and spread in the masses of ready-carbonized mushroom. The glare on the horizon grew brighter through the hours. It also came nearer.

Burl shivered a little, as he watched. He had never even dreamed of fire before, and even the overhanging clouds were lighted by these flames. Over a stretch at least a dozen miles in length and from half a mile to three miles across, the seething furnaces and columns of flame-lit smoke sent illumination over the world. It was like the glow the lights of a city can throw upon the sky. And like the flitting of aircraft above a city was the assembly of fascinated creatures of the night.

Great moths and flying beetles, gigantic gnats and midges grown huge upon this planet, fluttered and danced above the flames. As the fire came nearer, Burl could see them: colossal, delicately-formed creatures sweeping above the white-hot expanse. There were moths with riotously-colored wings of thirty-foot spread, beating the air with mighty strokes, their huge eyes glowing like garnets as they stared intoxicatedly at the incandescence below them.

Burl saw a great peacock-moth soaring above the hills with wings all of forty feet across. They fluttered like sails of unbelievable magnificence. And this was when all the separate flames had united to form a single sheet of white-hot burning stuff spread across the land for miles.

Feathery antennae of the finest lace spread out before the head of the peacock-moth; its body was of softest velvet. A ring of snow-white fur marked where its head began. The glare from below smote the maroon of its body with a strange effect. For one instant it was outlined clearly. Its eyes shone more redly than any ruby's fire. The great, delicate wings were poised in flight. Burl caught the flash of flame upon the two great irridescent spots on the wings. Shining purple and bright red, all the glory of chalcedony and of chrysoprase was reflected in the glare of burning fungi.

And then Burl saw it plunge downward, straight into the thickest and fiercest of the leaping flames. It flung itself into the furnace as a willing, drunken victim of their beauty.

Flying beetles flew clumsily above the pyre also, their horny wing-cases stiffly outstretched. In the light from below they shone like burnished metal. Their clumsy bodies, with spurred and fierce-toothed limbs, darted through the flame-lit smoke like so many grotesque meteors.

Burl saw strange collisions and still stranger meetings. Male and female flying creatures circled and spun in the glare, dancing their dance of love and death. They mounted higher than Burl could see, drunk with the ecstasy of living, and then descended to plunge headlong in the roaring flames below.

From every side the creatures came. Moths of brightest yellow, with furry bodies palpitant with life, flew madly to destruction. Other moths of a deepest black, with gruesome symbols on their wings, swiftly came to dance above the glow like motes in sunlight.

And Burl crouched beneath a toadstool, watching while the perpetual, slow raindrops fell and fell, and a continuous hissing noise came from where the rain splashed amid the flames.