***

  He knew he was acting strangely. There was no reason to see Leavitt. Leavitt was all right, perfectly fine, in no danger. In going to see him, Hall knew that he was trying to forget the other, more immediate problems. As he entered the infirmary, he felt guilty.

  His technician said, "He's sleeping."

  "Post-ictal," Hall said. Persons after a seizure usually slept.

  "Shall we start Dilantin?"

  "No. Wait and see. Perhaps we can hold him on phenobarb."

  He began a slow and meticulous examination of Leavitt. His technician watched him and said, "You're tired."

  "Yes," said Hall. "It's past my bedtime."

  On a normal day, he would now be driving home on the expressway. So would Leavitt: going home to his family in Pacific Palisades. The Santa Monica Expressway.

  He saw it vividly for a moment, the long lines of cars creeping slowly forward.

  And the signs by the side of the road. Speed limit 65 maximum, 40 minimum. They always seemed like a cruel joke at rush hour.

  Maximum and minimum.

  Cars that drove slowly were a menace. You had to keep traffic moving at a fairly constant rate, little difference between the fastest and the slowest, and you had to...

  He stopped.

  "I've been an idiot," he said.

  And he turned to the computer.

  ***

  In later weeks, Hall referred to it as his "highway diagnosis. " The principle of it was so simple, so clear and obvious, he was surprised none of them had thought of it before.

  He was excited as he punched in instructions for the GROWTH program into the computer; he had to punch in the directions three times; his fingers kept making mistakes.

  At last the program was set. On the display screen, he saw what he wanted: growth of Andromeda as a function of pH, of acidity-alkalinity.

  The results were quite clear:

  [GRAPHIC: colony growth versus pH, bell shaped curve centered at pH 7.41 and dying at 7.39/7.43]

  The Andromeda Strain grew within a narrow range. If the medium for growth was too acid, the organism would not multiply. If it was too basic, it would not multiply. Only within the range of pH 7.39 to 7.43 would it grow well.

  He stared at the graph for a moment, then ran for the door. On his way out he grinned at his assistant and said, "It's all over. Our troubles are finished."

  He could not have been more wrong.

  28. The Test

  IN THE MAIN CONTROL ROOM, STONE WAS WATCHING the television screen that showed Burton in the sealed lab.

  "The oxygen's going in," Stone said.

  "Stop it," Hall said.

  "What?"

  "Stop it now. Put him on room air."

  Hall was looking at Burton. On the screen, it was clear that the oxygen was beginning to affect him. He was no longer breathing so rapidly; his chest moved slowly.

  He picked up the microphone.

  "Burton," he said, "this is Hall. I've got the answer. The Andromeda Strain grows within a narrow range of pH. Do you understand? A very narrow range. If you're either acidotic or alkalotic, you'll be all right. I want you to go into respiratory alkalosis. I want you to breathe as fast as you can."

  Burton said, "But this is pure oxygen. I'll hyperventilate and pass out. I'm a little dizzy now."

  "No. We're switching back to air. Now start breathing as fast as you can."

  Hall turned back to Stone. "Give him a higher carbon dioxide atmosphere."

  "But the organism flourishes in carbon dioxide!"

  "I know, but not at an unfavorable pH of the blood. You see, that's the problem: air doesn't matter, but blood does. We have to establish an unfavorable acid balance for Burton's blood."

  Stone suddenly understood. "The child," he said. "It screamed.

  "Yes."

  "And the old fellow with the aspirin hyperventilated."

  "Yes. And drank Sterno besides."

  "And both of them shot their acid-base balance to hell," Stone said.

  "Yes," Hall said. "My trouble was, I was hung up on the acidosis. I didn't understand how the baby could become acidotic. The answer, of course, was that it didn't. It became basic-- too little acid. But that was all right-- you could go either way, too much acid or too little-- as long as you got out of the growth range of Andromeda."

  He turned back to Burton. "All right now," he said. "Keep breathing rapidly. Don't stop. Keep your lungs going and blow off your carbon dioxide. How do you feel?"

  "Okay," Burton panted. "Scared...but...okay."

  "Good."

  "Listen," Stone said, "we can't keep Burton that way forever. Sooner or later..."

  "Yes," Hall said. "We'll alkalinize his blood."

  To Burton: "Look around the lab. Do you see anything we could use to raise your blood pH?

  Burton looked. "No, not really."

  "Bicarbonate of soda? Ascorbic acid? Vinegar?"

  Burton searched frantically among the bottles and reagents on the lab shelf, and finally shook his head. "Nothing here that will work."

  Hall hardly heard him. He had been counting Burton's respirations; they were up to thirty-five a minute, deep and full. That would hold him for a time, but sooner or later he would become exhausted-- breathing was hard work-- or pass out.

  He looked around the lab from his vantage point. And it was while doing this that he noticed the rat. A black Norway, sitting calmly in its cage in a corner of the room, watching Burton.

  He stopped.

  "That rat..."

  It was breathing slowly and easily. Stone saw the rat and said, "What the hell..."

  And then, as they watched, the lights began to flash again, and the computer console blinked on:

  EARLY DEGENERATIVE CHANGE IN GASKET V-1 12-6886

  "Damn," Stone said.

  "Where does that gasket lead?"

  "It's one of the core gaskets; it connects all the labs. The main seal is--"

  The computer came back on.

  DEGENERATIVE CHANGE IN GASKETS

  A-009-5478

  V-430-0030

  N-966-6656

  They looked at the screen in astonishment. "Something is wrong," Stone said. "Very wrong."

  In rapid succession the computer flashed the number of nine more gaskets that were breaking down.

  "I don't understand..."

  And then Hall said, "The child. Of course!"

  "The child?"

  "And that damned airplane. It all fits."

  "What are you talking about?" Stone said.

  "The child was normal," Hall said. "It could cry, and disrupt it's acid-base balance. Well and good. That would prevent the Andromeda Strain from getting into its bloodstream, and multiplying, and killing it."

  "Yes, yes," Stone said. "You've told me all that."

  "But what happens when the child stops crying?

  Stone stared at him. He said nothing.

  "I mean," Hall said, "that sooner or later, that kid had to stop crying. It couldn't cry forever. Sooner or later, it would stop, and its acid-base balance would return to normal. Then it would be vulnerable to Andromeda."

  "True."

  "But it didn't die."

  "Perhaps some rapid form of immunity."

  "No. Impossible. There are only two explanations. When the child stopped crying, either the organism was no longer there-had been blown away, cleared from the air-or else the organism-"

  "Changed," Stone said. "Mutated."

  "Yes. Mutated to a noninfectious form. And perhaps it is still mutating. Now it is no longer directly harmful to man, but it eats rubber gaskets."

  "The airplane."

  Hall nodded. "National guardsmen could be on the ground, and not be harmed. But the pilot had his aircraft destroyed because the plastic was dissolved before his eyes."

  "So Burton is now exposed to a harmless organism. That's why the rat is alive."

  "That's why Burton is alive," Hall said. "The rapid breathing isn't necessary. He's only alive because Andromeda changed."

  "It may change again," Stone said. "And if most mutations occur at times of multiplication, when the organism is growing most rapidly..."

  The sirens went off, and the computer flashed a message in red.

  GASKET INTEGRITY ZERO. LEVEL V CONTAMINATED AND SEALED.

  Stone turned to Hall. "Quick," he said, "get out of here. There's no substation in this lab. You have to go to the next sector."

  For a moment, Hall did not understand. He continued to sit in his seat, and then, when the realization hit him, he scrambled for the door and hurried outside to the corridor. As he did so he heard a hissing sound, and a thump as a massive steel plate slid out from a wall and closed off the corridor.

  Stone saw it and swore. "That does it," he said. "We're trapped here. And if that bomb goes off, it'll spread the organism all over the surface. There will be a thousand mutations, each killing in a different way. We'll never be rid of it."

  Over the loudspeaker, a flat mechanical voice was saying, "The level is closed. The level is closed. This is an emergency. The level is closed."

  There was a moment of silence, and then a scratching sound as a new recording came on, and Miss Gladys Stevens of Omaha, Nebraska, said quietly, "There are now three minutes to atomic self-destruct."

  29. Three Minutes

  A NEW RISING AND FALLING SIREN CAME ON, AND all the clocks snapped their hands back to 1200 hours, and the second hands began to sweep out the time. The stop-clocks all glowed red, with a green line on the dial to indicate when detonation would occur.

  And the mechanical voice repeated calmly, "There are now three minutes to self-destruct."

  "Automatic," Stone said quietly. "The system cuts in when the level is contaminated. We can't let it happen."

  Hall was holding the key in his hand. "There's no way to get to a substation?"

  "Not on this level. Each sector is sealed from every other.

  "But there are substations, on the other levels?"

  "Yes..."

  "How do I get up?"

  "You can't. All the conventional routes are sealed.

  "What about the central core?" The central core communicated with all levels.

  Stone shrugged. "The safeguards .

  Hall remembered talking to Burton earlier about the central-core safeguards. In theory, once inside the central core you could go straight to the top. But in practice, them were ligamine sensors located around the core to prevent this. Originally intended to prevent escape of lab animals that might break free into the core, the sensors released ligamine, a curare derivative that was water-soluble, in the form of a gas. There were also automatic guns that fired ligamine darts.

  The mechanical voice said, "There are now two minutes forty-five seconds to self-destruct."

  Hall was already moving back into the lab and staring through the glass into the inner work area; beyond that was the central core.

  Hall said, "What are my chances?"

  "They don't exist," Stone explained.

  Hall bent over and crawled through a tunnel into a plastic suit. He waited until it had sealed behind him, and then he picked up a knife and cut away the tunnel, like a tail. He breathed in the air of the lab, which was cool and fresh, and laced with Andromeda organisms.

  Nothing happened.

  Back in the lab, Stone watched him through the glass. Hall saw his lips move, but heard nothing; then a moment later the speakers cut in and he heard Stone say, "-- best that we could devise."

  "What was?"

  "The defense system."

  "Thanks very much," Hall said, moving toward the rubber gasket. It was circular and rather small, leading into the central core.

  "There's only one chance," Stone. said. "The doses are low. They're calculated for a ten-kilogram animal, like a large monkey, and you weigh seventy kilograms or so. You can stand a fairly heavy dose before--"

  "Before I stop breathing," Hall said. The victims of curare suffocate to death, their chest muscles and diaphragms paralyzed. Hall was certain it was an unpleasant way to die.

  "Wish me luck," he said.

  "There are now two minutes thirty seconds to self-destruct," Gladys Stevens said.

  Hall slammed the gasket with his fist, and it crumbled in a dusty cloud. He moved out into the central core.

  ***

  It was silent. He was away from the sirens and flashing lights of the level, and into a cold, metallic, echoing space. The central core was perhaps thirty feet wide, painted a utilitarian gray; the core itself, a cylindrical shaft of cables and machinery, lay before him. On the walls he could see the rungs of a ladder leading upward to Level IV.

  "I have you on the TV monitor, " Stone's voice said. "Start up the ladder. The gas will begin any moment."

  A new recorded voice broke in. "The central core has been contaminated," it said. "Authorized maintenance personnel are advised to clear the area immediately."

  "Go!" Stone said.

  Hall climbed. As he went up the circular wall, he looked back and saw pale clouds of white smoke blanketing the floor.

  "That's the gas," Stone said. "Keep going."

  Hall climbed quickly, hand over hand, moving up the rungs. He was breathing hard, partly from the exertion, partly from emotion.

  "The sensors have you," Stone said. His voice was dull.

  Stone was sitting in the Level V laboratory, watching on the consoles as the computer electric eyes picked up Hall and outlined his body moving up the wall. To Stone he seemed painfully vulnerable. Stone glanced over at a third screen, which showed the ligamine ejectors pivoting on their wall brackets, the slim barrels coming around to take aim.

  "Go!"

  On the screen, Hall's body was outlined in red on a vivid green background. As Stone watched, a crosshair was superimposed over the body, centering on the neck. The computer was programmed to choose a region of high blood flow; for most animals, the neck was better than the back.

  Hall, climbing up the core wall, was aware only of the distance and his fatigue. He felt strangely and totally exhausted, as if he had been climbing for hours. Then he realized that the gas was beginning to affect him.

  "The sensors have picked you up," Stone said. "But you have only ten more yards."

  Hall glanced back and saw one of the sensor units. It was aimed directly at him. As he watched, it fired, a small puff of bluish smoke spurting from the barrel. There was a whistling sound, and then something struck the wall next to him, and fell to the ground.

  "Missed that time. Keep going."

  Another dart slammed into the wall near his neck. He tried to hurry, tried to move faster. Above, he could see the door with the plain white markings LEVEL IV. Stone was right; less than ten yards to go.

  A third dart, and then a fourth. He still was untouched. For an ironic moment he felt irritation: the damned computers weren't worth anything, they couldn't even hit a simple target...

  The next dart caught him in the shoulder, stinging as it entered his flesh, and then there was a second wave of burning pain as the liquid was injected. Hall swore.

  Stone watched it all on the monitor. The screen blandly recorded STRIKE and then proceeded to rerun a tape of the sequence, showing the dart moving through the air, and hitting Hall's shoulder. It showed it three times in succession.

  The voice said, "There are now two minutes to self-destruct.

  "It's a low dose," Stone said to Hall. "Keep going."

  Hall continued to climb. He felt sluggish, like a four-hundred pound man, but he continued to climb. He reached the next door just as a dart slammed into the wall near his cheekbone.

  "Nasty."

  "Go! Go!"

  The door had a seal and handle. He tugged at the handle while still another dart struck the wall.

  "That's it, that's it, you're going to make it," Stone said.

  "There are now ninety seconds to self-destruct," the voice said.

  The handle spun. With a hiss of air the door came open. He moved into an inner chamber just as a dart struck his leg with a brief, searing wave of heat. And suddenly, instantly, he was a thousand pounds heavier. He moved in slow motion as he reached for the door and pulled it shut behind him.

  "You're in an airlock," Stone said. "Turn the next door handle."

  Hall moved toward the inner door. It was several miles away, an infinite trip, a distance beyond hope. His feet were encased in lead; his legs were granite. He felt sleepy and achingly tired as he took one step, and then another, and another.

  "There are now sixty seconds to self-destruct."

  Time was passing swiftly. He could not understand it; everything was so fast, and he was so slow.

  The handle. He closed his fingers around it, as if in a dream. He turned the handle.

  "Fight the drug. You can do it," Stone said.

  What happened next was difficult to recall. He saw the handle turn, and the door open; he was dimly aware of a girl, a technician, standing in the hallway as he staggered through.

  She watched him with frightened eyes as he took a single clumsy step forward.

  "Help me," he said.

  She hesitated; her eyes got wider, and then she ran down the corridor away from him.

  He watched her stupidly, and fell to the ground. The substation was only a few feet away, a glittering, polished metal plate on the wall.

  "Forty-five seconds to self-destruct," the voice said, and then he was angry because the voice was female, and seductive, and recorded, because someone had planned it this way, had written out a series of inexorable statements, like a script, which was now being followed by the computers, together with all the polished, perfect machinery of the laboratory. It was as if this was his fate, planned from the beginning.

  And he was angry.

  Later, Hall could not remember how he managed to crawl the final distance; nor could he remember how he was able to get to his knees and reach up with the key. He did remember twisting it in the lock, and watching as the green light came on again.

  "Self-destruct has been canceled," the voice announced, as if it were quite normal.

  Hall slid to the floor, heavy, exhausted, and watched as blackness closed in around him.

  DAY 5

  Resolution

  30. The Last Day

  AVOICE FROM VERY FAR AWAY SAID, "He's fighting it."

  "Is he?"

  "Yes. Look."

  And then, a moment later, Hall coughed as something was pulled from his throat, and he coughed again, gasped for air, and opened his eyes.

  A concerned female face looked down at him. "You okay? It wears off quickly."

  Hall tried to answer her but could not. He lay very still on his back, and felt himself breathe. It was a little stiff at first, but soon became much easier, his ribs going in and out without effort. He turned his head and said, "How long?"

  "About forty seconds," the girl said, "as nearly as we can figure. Forty seconds without breathing. You were a little blue when we found you, but we got you intubated right away and onto a respirator."

  "When was that?"

  "Twelve, fifteen minutes ago. Ligamine is short-acting, but even so, we were worried about you... How are you feeling?"

  "Okay."

  He looked around the room. He was in the infirmary on Level IV. On the far wall was a television monitor, which showed Stone's face.

  "Hello," Hall said.

  Stone grinned. "Congratulations."

  "I take it the bomb didn't?"

  "The bomb didn't," Stone said.

  "That's good," Hall said, and closed his eyes. He slept for more than an hour, and when he awoke the television screen was blank. A nurse told him that Dr. Stone was talking to Vandenburg.

  "What's happening?"

  "According to predictions, the organism is over Los Angeles now."

  "And?"

  The nurse shrugged. "Nothing. It seems to have no effect at all."

  ***

  "None whatsoever," Stone said, much later. "It has apparently mutated to a benign form. We're still waiting for a bizarre report of death or disease, but it's been six hours now, and it gets less likely with every minute. We suspect that ultimately it will migrate back out of the atmosphere, since there's too much oxygen down here. But of course if the bomb had gone off in Wildfire..."

  Hall said, "How much time was left?"

  "When you turned the key? About thirty-four seconds."

  Hall smiled. "Plenty of time. Hardly even exciting."

  "Perhaps from where you were," Stone said. "But down on Level V, it was very exciting indeed. I neglected to tell you that in order to improve the subterranean detonation characteristics of the atomic device, all air is evacuated from Level V, beginning thirty seconds before explosion."

  "Oh," Hall said.

  "But things are now under control," Stone said. "We have the organism, and can continue to study it. We've already begun to characterize a variety of mutant forms. It's a rather astonishing organism in its versatility. " He smiled. "I think we can be fairly confident that the organism will move into the upper atmosphere without causing further difficulty on the surface, so there's no problem there. And as for us down here, we understand what's happening now, in terms of the mutations. That's the important thing. That we understand."

  "Understand," Hall repeated.

  "Yes," Stone said. "We have to understand."

  ***

  EPILOGUE

  OFFICIALLY, THE LOSS OF ANDROS V, THE MANNED spacecraft that burned up as it reentered the atmosphere, was explained on the basis of mechanical failure. The tungsten-and-plastic-laminate heat shield was said to have eroded away under the thermal stress of returning to the atmosphere, and an investigation was ordered by NASA into production methods for the heat shield.

  In Congress, and in the press, there was clamor for safer spacecraft. As a result of governmental and public pressure, NASA elected to postpone future manned flights for an indefinite period. This decision was announced by Jack Marriott, "the voice of Andros," in a press conference at the Manned Spaceflight Center in Houston. A partial transcript of the conference follows:

  Q: Jack, when does this postponement go into effect?

  A: Immediately. Right as I talk to you, we are shutting down. Q: How long do you anticipate this delay will last?

  A: I'm afraid that's impossible to say. Q: Could it be a matter of months? A: It could. Q: Jack, could it be as long as a year9

  A: It's just impossible for me to say. We must wait for the findings of the investigative committee.

  Q: Does this postponement have anything to do with the Russian decision to curtail their space program after the crash of Zond 19?

  A: You'd have to ask the Russians about that.

  Q: I see that Jeremy Stone is on the list of the investigative committee. How did you happen to include a bacteriologist?

  A: Professor Stone has served on many scientific advisory councils in the past. We value his opinion on a broad range of subjects.

  Q: What will this delay do to the Mars-landing target date?

  A: It will certainly set the scheduling back.

  Q: Jack, how far?

  A: I'll tell you frankly, it's something that all of us here would like to know. We regard the failure of Andros V as a scientific error, a breakdown in systems technology, and not as a specifically human error. The scientists are going over the problem now, and we'll have to wait for their findings. The decision is really out of our hands.

  Q: Jack, would you repeat that?

  A: The decision is out of our hands.