Until they could not see, the dogs prowled and slaughtered.
At night they came in bloody, most of it not their own, and exhausted. Marin pumped them full of antibiotics, bandaged their wounds, fed them through their veins, and shot them into sleep. In the morning he awakened them with an injection of stimulant and sent them tingling into battle.
It took the rats two days to learn they could not feed during the day. Not so numerous, they came at night. They climbed on the vines and nibbled the fruit. They gnawed growing grain and ravaged vegetables.
The next day the colonists set up lights. The dogs were with them, discouraging the few rats who were still foolish enough to forage while the sun was overhead.
An hour before dusk, Marin called the dogs in and gave them an enforced rest. He brought them out of it after dark and took them to the fields, staggering. The scent of rats revived them; they were as eager as ever, if not quite so fast.
The rats came from the surrounding meadows, not singly, or in twos and threes, as they had before; this time they came together. Squealing and rustling the grass, they moved toward the fields. It was dark, and though he could not see them, Marin could hear them. He ordered the great lights turned on in the area of the fields.
The rats stopped under the glare, milling around uneasily. The dogs quivered and whined. Marin held them back. The rats resumed their march, and Marin released the dogs.
The dogs charged in to attack, but didn’t dare brave the main mass. They picked off the stragglers and forced the rats into a tighter formation. After that the rats were virtually unassailable.
The colonists could have burned the bunched-up rats with the right equipment, but they didn’t have it and couldn’t get it for years. Even if they’d had it, the use of such equipment would endanger the crops, which they had to save if they could. It was up to the dogs.
The rat formation came to the edge of the fields, and broke. They could face a common enemy and remain united, but in the presence of food, they forgot that unity and scattered—hunger was the great divisor. The dogs leaped joyously in pursuit. They hunted down the starved rodents, one by one, and killed them as they ate.
When daylight came, the rat menace had ended.
The next week the colonists harvested and processed the food for storage and immediately planted another crop.
MARIN sat in the lab and tried to analyze the situation. The colony was moving from crisis to crisis; all of them involving food. In itself, each critical situation was minor, but lumped together they could add up to failure. No matter how he looked at it, they just didn’t have the equipment they needed to colonize Glade.
The fault seemed to lie with Biological Survey; they hadn’t reported the presence of pests that were endangering the food supply. Regardless of what the exec thought about them, Survey knew their business. If they said there were no mice or rats on Glade, then there hadn’t been any—when the survey was made.
The question was: when did they come and how did they get here?
Marin sat and stared at the wall, turning over hypotheses in his mind, discarding them when they failed to make sense.
His gaze shifted from the wall to the cage of the omnivores, the squirrel-size forest creature. The most numerous animal on Glade, it was a commonplace sight to the colonists.
And yet it was a remarkable animal, more than he had realized. Plain, insignificant in appearance, it might be the most important of any animal Man had encountered on the many worlds he had settled on. The longer he watched, the more Marin became convinced of it.
He sat silent, observing the creature, not daring to move. He sat until it was dark and the omnivore resumed its normal activity.
Normal? The word didn’t apply on Glade.
The interlude with the omnivore provided him with one answer. He needed another one; he thought he knew what it was, but he had to have more data, additional observations.
He set up his equipment carefully on the fringes of the settlement. There and in no other place existed the information he wanted.
He spent time in the digger, checking his original investigations. It added up to a complete picture.
When he was certain of his facts, he called on Hafner.
The executive was congenial; it was a reflection of the smoothness with which the objectives of the colony were being achieved. “Sit down,” he said affably. “Smoke?”
The biologist sat down and took a cigarette.
“I thought you’d like to know where the mice came from,” he began.
Hafner smiled. “They don’t bother us any more.”
“I’ve also determined the origin of the rats.”
“They’re under control. We’re doing nicely.”
ON the contrary, thought Marin. He searched for the proper beginning.
“Glade has an Earth-type climate and topography,” he said. “Has had for the past twenty thousand years. Before that, about a hundred million years ago, it was also like Earth of the comparable period.”
He watched the look of polite interest settle on the executive’s face as he stated the obvious. Well, it was obvious, up to a point. The conclusions weren’t, though.
“Between a hundred million years and twenty thousand years ago, something happened to Glade,” Marin went on. “I don’t know the cause; it belongs to cosmic history and we may never find out. Anyway, whatever the cause—fluctuations in the sun, unstable equilibrium of forces within the planet, or perhaps an encounter with an interstellar dust cloud of variable density—the climate on Glade changed.
“It changed with inconceivable violence and it kept on changing. A hundred million years ago, plus or minus, there was carboniferous forest on Glade. Giant reptiles resembling dinosaurs and tiny mammals roamed through it. The first great change wiped out the dinosaurs, as it did on Earth. It didn’t wipe out the still more primitive ancestor of the omnivore, because it could adapt to changing conditions.
“Let me give you an idea how the conditions changed. For a few years a given area would be a desert; after that it would turn into a jungle. Still later a glacier would begin to form. And then the cycle would be repeated, with wild variations. All this might happen—did happen—within a span covered by the lifetime of a single omnivore. This occurred many times. For roughly a hundred million years: it was the norm of existence on Glade. This condition was hardly conducive to the preservation of fossils.”
Hafner saw the significance and was concerned. “You mean these climatic fluctuations suddenly stopped, twenty thousand years ago? Are they likely to begin again?”
“I don’t know,” confessed the biologist. “We can probably determine it if we’re interested.” The exec nodded grimly. “We’re interested, all right.” Maybe we are, thought the biologist. He said, “The point is that survival was difficult. Birds could and did fly to more suitable climates; quite a few of them survived. Only one species of mammals managed to come through.”
“Your facts are not straight,” observed Hafner. “There are four species, ranging in size from a squirrel to a water buffalo.”
“One species,” Marin repeated doggedly. “They’re the same. If the food supply for the largest animal increases, some of the smaller so-called species grow up. Conversely, if food becomes scarce in any category, the next generation, which apparently can be produced almost instantly, switches to a form which does have an adequate food supply.”
“The mice,” Hafner said slowly.
MARIN finished the thought for him. “The mice weren’t here when we got here. They were born of the squirrel-size omnivore.”
Hafner nodded. “And the rats?”
“Born of the next larger size. After all, we’re environment, too —perhaps the harshest the beasts have yet faced.”
Hafner was a practical man, trained to administer a colony. Concepts were not his familiar ground. “Mutations, then? But I thought—”
The biologist smiled. It was thin and cracked at the edges of his mouth.
“On Earth, it would be mutation. Here it is merely normal evolutionary adaptation.” He shook his head. “I never told you, but omnivores, though they could be mistaken for an animal from Earth, have no genes or chromosomes. Obviously they do have heredity, but how it is passed down, I don’t know. However it functions, it responds to external conditions far faster than anything we’ve ever encountered.”
Hafner nodded to himself. “Then we’ll never be free from pests.” He clasped and unclasped his hands. “Unless, of course, we rid the planet of all animal life.”
“Radioactive dust?” asked the biologist.
“They have survived worse.”
The exec considered alternatives. “Maybe we should leave the planet and leave it to the animals.”
“Too late,” said the biologist. “They’ll be on Earth, too, and all the planets we’ve settled on.” Hafner looked at him. The same pictures formed in his mind that Marin had thought of. Three ships had been sent to colonize Glade. One had remained with the colonists, survival insurance in case anything unforeseen happened. Two had gone back to Earth to carry the report that all was well and that more supplies were needed. They had also carried specimens from the planet.
The cages those creatures were kept in were secure. But a smaller species could get out, must already be free, inhabiting, undetected, the cargo spaces of the ships.
There was nothing they could do to intercept those ships. And once they reached Earth, would the biologists suspect? Not for a long time. First a new kind of rat would appear. A mutation could account for that. Without-specific knowledge, there would be nothing to connect it with the specimens picked up from Glade. “We have to stay,” said the biologist. “We have to study them and we can do it best here.” He thought of the vast complex of buildings on Earth. There was too much invested to tear them down and make them verminproof. Billions of people could not be moved off the planet while the work was being done.
They were committed to Glade not as a colony, but as a gigantic laboratory. They had gained one planet and lost the equivalent of ten, perhaps more when the destructive properties of the omnivores were finally assessed.
A rasping animal cough interrupted the biologist’s thoughts. Hafner jerked his head and glanced out the window. Lips tight, he grabbed a rifle off the wall and ran out. Marin followed him.
THE EXEC headed toward the fields where the second fast crop was maturing. On top of a knoll, he stopped and knelt. He flipped the dial to extreme charge, aimed, and fired. It was high; he missed the animal in the field. A neat strip of smoking brown appeared in the green vegetation.
He aimed more carefully and fired again. The charge screamed out of the muzzle. It struck the animal on the forepaw. The beast leaped high in the air and fell down, dead and broiled.
They stood over the animal Hafner had killed. Except for the lack of markings, it was a good imitation of a tiger. The exec prodded it with his toe.
“We chase the rats out of the warehouse and they go to the fields,” he muttered. “We hunt them down in the fields with dogs and they breed tigers.”
“Easier than rats,” said Marin. “We can shoot tigers.” He bent down over the slain dog near which they had surprised the big cat.
The other dog came whining from the far corner of the field to which he had fled in terror. He was a courageous dog, but he could not face the great carnivore. He whimpered and licked the face of his mate.
The biologist picked up the mangled dog and headed toward the laboratory.
“You can’t save her,” said Hafner morosely. “She’s dead.”
“But the pups aren’t. We’ll need them. The rats won’t disappear merely because tigers have showed up.”
The head drooped limply over his arm and blood seeped into his clothing as Hafner followed him up the hill.
“We’ve been here three months,” the exec said suddenly. “The dogs have been in the fields only two. And yet the tiger was mature. How do you account for something like that?”
Marin bent under the weight of the dog. Hafner never would understand his bewilderment. As a biologist, all his categories were upset. What did evolution explain? It was a history of organic life on a particular world. Beyond that world, it might not apply. Even about himself there were many things Man didn’t know, dark patches in his knowledge which theory simply had to pass over. About other creatures, his ignorance was sometimes limitless.
Birth was simple; it occurred on countless planets. Meek grazing creatures, fierce carnivores—the most unlikely animals gave birth to their young. It happened all the time. And the young grew up, became mature and mated. He remembered that evening in the laboratory. It was accidental—what if he had been elsewhere and not witnessed it? They would not know what little they did.
He explained it carefully to Hafner. “If the survival factor is high and there’s a great disparity in size, the young need not ever be young. They may be born as fully functioning adults!”
ALTHOGH not at the rate it had initially set, the colony progressed. The fast crops were slowed down and a more diversified selection was planted. New buildings were constructed and the supplies that were stored in them were spread out thin, for easy inspection.
The pups survived and within a year shot up to maturity. After proper training, they were released to the fields where they joined the older dogs. The battle against the rats went on; they were held in check, though the damage they caused was considerable.
The original animal, unchanged in form, developed an appetite for electrical insulation. There was no protection except to keep the power on at all times. Even then there were unwelcome interruptions until the short was located and the charred carcass was removed. Vehicles were kept tightly closed or parked only in verminproof buildings. While the plague didn’t increase in numbers, it couldn’t be eliminated, either.
There was a flurry of tigers, but they were larger animals and were promptly shot down. They prowled at night, so the colonists were assigned to guard the settlement around the clock. Where lights failed to reach, the infra-red ‘scope did. As fast as they came, the tigers died. Except for the first one, not a single dog was lost.
The tigers changed, though not in form. Externally, they were all big and powerful killers. But as the slaughter went on, Marin noticed one astonishing fact—the internal organic structure became progressively more immature.
The last one that was brought to him, for examination was the equivalent of a newly born cub. That tiny stomach was suited more for the digestion of milk than meat. How it had furnished energy to drive those great muscles was something of a miracle. But drive it had, for a murderous fifteen minutes before the animal was brought down. No lives were lost, though sick bay was kept busy for a while.
That was the last tiger they shot. After that, the attacks ceased.
The seasons passed and nothing new occurred. A spaceship civilization or even that fragment of it represented by the colony was too much for the creature, which Marin by now had come to think of as the “Omnimal.” It had evolved out of a cataclysmic past, but it could not meet the challenge of the harshest environment.
Or so it seemed.
THREE months before the next colonists were due, a new animal was detected. Food was missing from the fields. It was not another tiger: they were carnivorous. Nor rats, for vines were stripped in a manner that no rodent could manage.
The food was not important. The colony had enough in storage. But if the new animal signaled another plague, it was necessary to know how to meet it. The sooner they knew what the animal was, the better defense they could set up against it.
Dogs were useless. The animal roamed the field they were loose in, and they did not attack nor even seem to know it was there.
The colonists were called upon for guard duty again, but it evaded them. They patrolled for a week and they still did not catch sight of it.
Hafner called them in and rigged up an alarm system in the field most frequented by the animal.
It detected that, too, and moved its sphere of operations to a field in which the alarm system had not been installed.
Hafner conferred with the engineer, who devised an alarm that would react to body radiation. It was buried in the original field and the old alarm was moved to another.
Two nights later, just before dawn, the alarm rang.
Marin met Hafner at the edge of the settlement. Both carried rifles. They walked; the noise of any vehicle was likely to frighten the animal. They circled around and approached the field from the rear. The men in the camp had been alerted. If they needed help, it was ready.
They crept silently through the underbrush. It was feeding in the field, not noisily, yet they could hear it. The dogs hadn’t barked.