The Big Book of Science Fiction

by The Big Book of Science Fiction (retail) (epub)

  It carried an outsize ultrasonic generator and a device for directing the beam into the planet. That was the sending apparatus. The receiving end began with a large sonic lens which picked up sound beams reflected from any desired depth, converted them into electrical energy and thence into an image which was flashed onto a screen.

  At the depth of ten miles, the image was fuzzy, though good enough to distinguish the main features of the strata. At three miles, it was better. It could pick up the sound reflection of a buried coin and convert it into a picture on which the date could be seen.

  It was to a geologist as a microscope is to a biologist. Being a biologist, Dano Marin could appreciate the analogy.

  He started at the tip of the peninsula and zigzagged across, heading toward the isthmus. Methodically, he covered the territory, sleeping at night in the digger. On the morning of the third day, he discovered oil traces, and by that afternoon he had located the main field.

  He should probably have turned back at once, but now that he had found oil, he investigated more deliberately. Starting at the top, he let the image range downward below the top strata.

  It was the reverse of what it should have been. In the top few feet, there were plentiful fossil remains, mostly of the four species of mammals. The squirrel-like creature and the far larger grazing animal were the forest dwellers. Of the plains animals, there were only two, in size fitting neatly between the extremes of the forest dwellers.

  After the first few feet, which corresponded to approximately twenty thousand years, he found virtually no fossils. Not until he reached a depth which he could correlate to the Late Carboniferous age on Earth did fossils reappear. Then they were of animals appropriate to the epoch. At that depth and below, the history of Glade was quite similar to Earth’s.

  Puzzled, he checked again in a dozen widely scattered localities. The results were always the same—fossil history for the first twenty thousand years, then none for roughly a hundred million. Beyond that, it was easy to trace the thread of biological development.

  In that period of approximately one hundred million years, something unique had happened to Glade. What was it?

  On the fifth day his investigations were interrupted by the sound of the keyed-on radio.

  “Marin.”

  “Yes?” He flipped on the sending switch.

  “How soon can you get back?”

  He looked at the photo-map. “Three hours. Two if I hurry.”

  “Make it two. Never mind the oil.”

  “I’ve found oil. But what’s the matter?”

  “You can see it better than I can describe it. We’ll discuss it when you get back.”

  —

  Reluctantly, Marin retracted the instruments into the digger. He turned it around and, with not too much regard for the terrain, let it roar. The treads tossed dirt high in the air. Animals fled squealing from in front of him. If the grove was small enough, he went around it, otherwise he went through and left matchsticks behind.

  He skidded the crawler ponderously to halt near the edge of the settlement. The center of activity was the warehouse. Pickups wheeled in and out, transferring supplies to a cleared area outside. He found Hafner in a corner of the warehouse, talking to the engineer.

  Hafner turned around when he came up. “Your mice have grown, Marin.”

  Marin looked down. The robot cat lay on the floor. He knelt and examined it. The steel skeleton hadn’t broken; it had been bent, badly. The tough plastic skin had been torn off and, inside, the delicate mechanism had been chewed into an unrecognizable mass.

  Around the cat were rats, twenty or thirty of them, huge by any standards. The cat had fought; the dead animals were headless or disemboweled, unbelievably battered. But the robot had been outnumbered.

  Biological Survey had said there weren’t any rats on Glade. They had also said that about mice. What was the key to their error?

  The biologist stood up. “What are you going to do about it?”

  “Build another warehouse, two-foot-thick fused dirt floors, monolithic construction. Transfer all perishables to it.”

  Marin nodded. That would do it. It would take time, of course, and power, all they could draw out of the recently set up atomic generator. All other construction would have to be suspended. No wonder Hafner was disturbed.

  “Why not build more cats?” Marin suggested.

  The executive smiled nastily. “You weren’t here when we opened the doors. The warehouse was swarming with rats. How many robot cats would we need—five, fifteen? I don’t know. Anyway the engineer tells me we have enough parts to build three more cats. The one lying there can’t be salvaged.”

  It didn’t take an engineer to see that, thought Marin.

  Hafner continued, “If we need more, we’ll have to rob the computer in the spaceship. I refuse to permit that.”

  Obviously he would. The spaceship was the only link with Earth until the next expedition brought more colonists. No exec in his right mind would permit the ship to be crippled.

  But why had Hafner called him back? Merely to keep him informed of the situation?

  Hafner seemed to guess his thoughts. “At night we’ll floodlight the supplies we remove from the warehouse. We’ll post a guard armed with decharged rifles until we can move the food into the new warehouse. That’ll take about ten days. Meanwhile, our fast crops are ripening. It’s my guess the rats will turn to them for food. In order to protect our future food supply, you’ll have to activate your animals.”

  The biologist started. “But it’s against regulations to loose any animal on a planet until a complete investigation of the possible ill effects is made.”

  “That takes ten or twenty years. This is an emergency and I’ll be responsible—in writing, if you want.”

  The biologist was effectively countermanded. Another rabbit-infested Australia or the planet that the snails took over might be in the making, but there was nothing he could do about it.

  “I hardly think they’ll be of any use against rats this size,” he protested.

  “You’ve got hormones. Apply them.” The executive turned and began discussing construction with the engineer.

  —

  Marin had the dead rats gathered up and placed in the freezer for further study.

  After that, he retired to the laboratory and worked out a course of treatment for the domesticated animals that the colonists had brought with them. He gave them the first injections and watched them carefully until they were safely through the initial shock phase of growth. As soon as he saw they were going to survive, he bred them.

  Next he turned to the rats. Of note was the wide variation in size. Internally, the same thing was true. They had the usual organs, but the proportions of each varied greatly, more than is normal. Nor were their teeth uniform. Some carried huge fangs set in delicate jaws; others had tiny teeth that didn’t match the massive bone structure. As a species, they were the most scrambled the biologist had ever encountered.

  He turned the microscope on their tissues and tabulated the results. There was less difference here between individual specimens, but it was enough to set him pondering. The reproductive cells were especially baffling.

  Late in the day, he felt rather than heard the soundless whoosh of the construction machinery. He looked out of the laboratory and saw smoke rolling upward. As soon as the vegetation was charred, the smoke ceased and heat waves danced into the sky.

  They were building on a hill. The little creatures that crept and crawled in the brush attacked in the most vulnerable spot, the food supply. There was no brush, not a blade of grass, on the hill when the colonists finished.

  —

  Terriers. In the past, they were the hunting dogs of the agricultural era. What they lacked in size they made up in ferocity toward rodents. They had earned their keep originally in granaries and fields, and, for a brief time, they were doing it again on colonial worlds where conditions were repeated.

  The do
gs the colonists brought had been terriers. They were still as fast, still with the same anti-rodent disposition, but they were no longer small. It had been a difficult job, yet Marin had done it well, for the dogs had lost none of their skill and speed in growing to the size of a Great Dane.

  The rats moved in on the fields of fast crops. Fast crops were made to order for a colonial world. They could be planted, grown, and harvested in a matter of weeks. After four such plantings, the fertility of the soil was destroyed, but that meant nothing in the early years of a colonial planet, for land was plentiful.

  The rat tide grew in the fast crops, and the dogs were loosed on the rats. They ranged through the fields, hunting. A rush, a snap of their jaws, the shake of a head, and the rat was tossed aside, its back broken. The dogs went on to the next.

  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 anymore.”

  “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 mammal 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 th
e 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.