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.