The Nitrogen Fix

by Hal Clement

  “Come along,” was all he said. The Nomad followed for a few meters and then paused, looking back toward the raft.

  “My wife will have to know where I’m going and for how long. Wait while I tell her; I’ll be right back.”

  The man shook his head. “We can’t wait. It wouldn’t be safe, and no one knows how long you’ll be gone anyway. One of us will stay here and tell your wife where you are if she seems too concerned.” The fellow gestured, and one of the others turned back. The rest gathered around Earrin as though prepared to use physical force to make him come along. The Nomad was surprised, resentful, and curious, but it seemed wisest to focus on the last of these attitudes. He began walking, and talking.

  “I still don’t see what you want me for. I don’t know what ‘bait’ means, and I don’t know why you’re bothered by someone following me.”

  “The someone is one of the Invaders,” one of the young women said patiently. “Maybe you don’t know about them and their danger to people — we only learned a few years ago ourselves, and haven’t had much chance to pass on the knowledge. We’d like to, but no one from the city could get to another, and there aren’t many Nomads to take messages. We need you to bring supplies — no one else has ever been able to get us copper. Maybe when we have a good stock you’d carry news for us to Beehive and Providence and other cities.”

  “I don’t know what ‘invader’ means either,” Earrin pointed out. “I’ve never seen anything following me around except a native — in fact, I’ve never seen anything which could follow anyone but people and natives. I’ve heard that you city folk don’t like natives much, but they’re certainly not dangerous. What we call ‘natives’ you’ve always called ‘animals,’ as I remember. Is that what you mean now by ‘invaders”‘ The woman’s reaction to Earrin’s word choice was much less emotional than Endrew’s would be to Kahvi’s an hour or so later. Of course, masks hid most facial expression, but it was still light enough to make out body attitudes. She appeared quite calm as she answered; so did the rest.

  “Yes, we used to call them animals. No doubt you learned that name in Surplus school — what was your city?”

  “Beehive.”

  “Ah, yes — down East some distance. Well, there was some excuse for calling the creatures natives, of course, when it was thought they were simply animals. They seemed to do no damage. They hung around eating wild vegetation and watching people without hurting them. It was strange that they spent so much time watching, and we wondered if they did have some intelligence and might really be pests if we tried to store air or food outside as I’ve heard some cities do.”

  “They do,” interjected Earrin.

  “Well, we don’t, so we didn’t worry about that.”

  Earrin wondered who “we” might be; all of this group were far too young to represent the general thought of the city. “Then, two or three years ago — ”

  “More like five,” cut in one of the young men.

  “Some years ago we discovered that they ate other things, and were dangerous.”

  “What else did they eat? What else is there for them to eat?” Fyn asked naturally.

  “I–I don’t like to say it-but-well, I suppose I’ll have to or you won’t be convinced. A few years ago one of my friends was outside, and saw one of the things watching a work group she wasn’t with. After a while it turned away and went off by itself, to a hollow on the hill where it was hard to see. She’d never seen one act that way, and found a place where she could watch. It was standing up, and seemed to be peeling a very thick layer of skin from its front. It put this on the ground when it was all separated, and presently the skin thickened and narrowed and turned into one of them. It had-it had-”

  “All right, it produced a child. What’s so deadly about that?” Earrin, who had never seen thephenomenon, was interested but had no sympathy with the city attitude toward everything connected with childbirth. These youngsters seemed to be trying to be independent, but had a long way to go.

  “It wasn’t that. There’s nothing wrong with having children, even when they’re surplus — we know that. But after a while this thing picked the baby up and handled it, and held it close —”

  “That’s still all right. We’ve — go on.”

  “Then-then it-it-the creature ate the child!

  Earrin had nothing to say. It did not even occur to him that the young woman could be exaggerating, much less actually lying, though he realized that Hiller morals did not quite match those of Nomads. He was silent for several minutes while the darkness deepened and the group walked steadily southward.

  The woman said nothing either, evidently satisfied with the effect she had produced. Earrin could not decide what to think, much less what to say; his mind kept sheering off the implications. Bones had taken care of Danna many times while her parents were out of sight.

  Finally the man remembered another point. “You said something about not considering them animals any more. I should have thought this would make them seem more like animals, if what I’ve heard about animals is true.”

  “This was something quite different. Actually, only a few of us know about the child-eating — we tried to tell some of the older people and they wouldn’t let us get past the first part. They’re just stuck in the slime.”

  Earrin was quite willing to agree with this, but suggested that she come back to the subject.

  “All right. I suppose you never learned much about scientific instruments.”

  “I’m surprised you had a chance to.”

  “Well, you naturally read books when people tell you not to. A lot of us have — in fact, since you certainly won’t tell anyone who matters, all of us and some others have read a lot about — well, such things. Experiments — ”

  One or two of the others murmured disapprovingly at the word-”and things like that.” She paid no attention to the sounds. “We work at such things, too, even though some of my less dedicated friends prefer not to use the real words. A few months ago we were setting up something outside, away from the locks and usual work areas where we weren’t likely to be found. It was a big sundial; we’d been reading about the way the sun moves in the sky during the year.

  “Anyone knows that,” remarked Earrin.

  “You see it more than we do. Beside, we wanted to — ” even the speaker hesitated a little this time — ”to measure what was happening.” There were no reactions this time from the others. “One of the creatures was watching while we put it together — we’d made the parts in our shop inside.

  The outside part took several days. On the second day some of the parts had been moved, and a piece I had been going to put in place had been installed by someone else — not one of us.”

  “We checked very carefully the third day, but couldn’t be sure anything had been handled. The next day, though, it was really certain. One of us remembered putting a piece in wrong. It was right the next morning.”

  “How do you know the-the native had done it?”

  “Who else could have? It wasn’t our group. No one else from the city would have known how.

  Neither would any Nomad.”

  “But you didn’t see it happen.”

  “Not then.” The voice was distinctly triumphant. “We set up another situation — ”

  “You mean an experiment,” Earrin couldn’t help remarking.

  “Watch it!” growled a male voice.

  “Oh no. Just a trial to see that no one from the city could have done it.” Darkness and mask saved Earrin from giving away his feelings. These were really children. He hoped Danna could be steered through this stage in a minimum of time.

  The illogic bothered him; if these youngsters had really rejected the dogma that science had changed the world’s air, and were now blaming Bones’ people, why did they still feel that scientific words were dirty? The city hangups, evidently, were pretty strong; maybe he should be sorry for the kids.”How did you do it, and what did you find out?” he as
ked.

  “We started a more complicated dial, got it partly set up, and went inside. A couple of watchers went out through another lock, hid near the work place, and watched-it was still daylight. The Invader waited only a few minutes. Then it went over, put the dial all together, looked at the shadow it made, and then took it apart and put the pieces back where they had been.”

  “Pretty conclusive, I have to admit.” Earrin was not, of course at all surprised, knowing Bones as well as he did — that was just what any of the natives would have done.

  “All right, so you’re afraid of them. They’re smart, and eat their own children. But they’re nitro-life, you know; how could they eat a person?”

  “Maybe they couldn’t, but anyone who would — ” the voice trailed away in a shudder, and Fyn again had nothing to say for a time. At last he changed the subject again.

  “I don’t see yet what you want me for.”

  “We’ll use you to help catch it,” a male voice boomed out of the darkness. “We need more of them to learn how to get rid of the things.”

  “More of them? You already have some? And why do you want to get rid of them, even if they have unpleasant ways?”

  The first woman took up the conversation again.

  “Yes, we caught the other one. The night after the test, we sent out a large group from the other lock and surrounded it. It didn’t try to get away when we drove it inside. We thought the oxygen would bother it, but it didn’t seem to notice any difference. The trouble is that with only one we can’t make tests likely to kill it, because then we couldn’t learn any more. When we catch this other one we won’t have to be so careful.”

  “You’d be willing to kill one? Just because you — ”

  “It’s not because they disgust us. There’s a much more important reason. We have a plan, and we can do it if the Invaders aren’t here to stop us.

  “I suppose you want to change the world’s air back.” The woman seemed a little startled, and became defensive.

  “Why not? And how did you know?”

  “I’m a Nomad. I’ve been through Surplus school. Most of us get that idea while we’re learning how to make air for ourselves.”

  “Well, why not?”

  “Because you can’t. The more photosynthetic oxygen makers you have working, and the more oxygen they make, the more and faster the nitrate-makers will work. You never get ahead on the oxygen, except in spaces so small that you can control which growths are around. The idea that there used to be an all-oxygen atmosphere is a pleasant myth, but if you’d spent all your life trying to keep yourself breathing, you’d know that’s all it ever was.”

  “Wrong.” The woman sounded very sure of herself. “That’s the trouble with having been afraid of science for hundreds of years; even people like you, who at least know it’s useful, don’t really know anything about it. You never had a chance to learn. We’ve been reading, and we have learned. I couldn’t explain things like equilibrium constants to you, or the way they apply to ecological systems, but we’ve found out that if you set up a system of oxygen-producers and enough growths that act as parasites on the nitro-makers, that system will spread provided it gets a good enough start. That start is the hard part; we’ll have to have a lot of help, a lot of people, to spread the growths in a lot of places at once; and we’ll have to get rid of the Invaders, because they must have done the same thing the other way to make the world the way they wanted it. They’d spoil what we were doing, so we’ll have to get rid of them. That’s why we need more specimens — we don’t know how to kill them yet.”

  “You’d really kill them if you caught them?”

  “Only one, just now, so as to learn. We don’t want to, of course, but until we’re rid of them we can’t get the world back the way it was, with air you can breathe, and no need to count children as Surplus and abort them out into the world as we have to do now. Wouldn’t you like to breathe air that wasn’t so thin it barely kept you alive?”“No, thanks.” Earrin didn’t have to think about that answer. If these people were all oxygen-wasters, he wanted no part of their plans. “The air I breathe is the kind people were made for. The stuff your friend was breathing is wasteful, and makes people silly after a while. Not for me; I have to be able to take care of myself — and one or two other people.”

  “But can’t you imagine walking around wherever you want, without having to wear masks and other protection?”

  Earrin could not, in fact, imagine anything of the sort. He didn’t believe the world had ever had breathable air, and didn’t believe it was possible to change it to such a condition; and he was not at all convinced that it would be a good idea to try. He did not have the intensely religious opposition to everything scientific which characterized the typical city-dweller, but he knew that any new line of action could have unforeseen results. He was willing to test a new air plant, but only one tray at a time. Had he been born a few thousand years earlier into an oxygen-rich atmosphere and grown up with the same attitude, he would have been intelligently cautious about large-scale burning of wood or coal.

  He mumbled some answer at the woman without remembering later what it was, and continued to think. The others seemed willing to let him do so; perhaps they hoped he had been impressed.

  He was, but not the way they hoped. The main point in Fyn’s mind at the moment was a straight piece of logic: the Hillers wanted to use him to help capture Bones. They wanted to kill, or try to kill, the native. Therefore, Earrin Fyn should get himself out of the hands of these Hillers, the sooner the better.

  He did not add a mental Q. E. D. because his reading background was negligible.

  How to get away? There were five of them, some walking ahead and some behind. Whether they were following a real path could not be ascertained in the darkness. In any case, the Hillers must know the area far better than Earrin himself did. He had been to one of the Blue Hill locks a few times, but always by the same route.

  Simply starting to run one way or the other was senseless. There would be bushes, and thorn branches, and slime, and rocks to run through, slip and trip on, and be slashed, torn and bruised by. The others wouldn’t even have to run to get him.

  And if he did get away they could still intercept him. He had enough air to last through the night, probably, if he were not too active. He would have to get to an oxygen supply before his cartridges were done. There were of course many jails scattered about Great Blue Hill, but it would be pure luck if he managed to find one in time even after the moon came up; all he could really count on locating were the jail at the landing place, his own raft at the same spot, and the city itself. His captors, who presumably knew the area, could get to any of these places before he could, if they knew which one he had in mind.

  Would they take the raft, where his wife was, for granted?

  Would they consider the city, or assume that he wouldn’t think of it, or wouldn’t want to face the troubles he would encounter inside — Nomads were easily recognizable and very unwelcome in civilized communities which kept track of their air. There really was no good and practical reason to justify, his going anywhere but home. It was becoming obvious why they weren’t bothering to tie him up or hold him tightly, even if they weren’t that confident of their powers of persuasion.

  He couldn’t go back to the raft or jail; they’d get him easily. In the city-well, even if Nomads weren’t welcome, there was something which might be worth doing. Earrin was a slow thinker, but a plan began to form.

  “Are we going all the way to the Hill tonight,” he asked suddenly. “We rowed a long way today, and I’m tired.” This was the truth, though not his principal reason for asking the question. His Nomad no-deceit hangup almost made him blurt out the latter as well, but he controlled himself rather unhappily.

  He felt even worse when one of the men answered with no sign of suspicion.

  “No, we’ll stop for rest and air soon — about half way. There’s a jail just before the slope gets steep.” />
  “Good. Thanks.” Earrin lapsed back into thought. There would be cartridges at the jail. No matter what the air status of his captors, they could restock quickly and, probably, beat Fyn back to the raft.

  Nothing was changed there.

  If he merely got out of their sight, that was probably what they would do; and even if they caught him later, one thing might be accomplished. If Bones were actually following, it would be possible to give hima warning about the new and more serious intentions of these Hillers.

  If, as seemed more likely, he were not, then Fyn could go on to the city and do something about the other native. Bones was the only one of the beings he knew, but he was prepared to regard them all as friends in spite of the woman’s horror story; he couldn’t attach much weight to the words of these young people even though he couldn’t bring himself to believe that they would lie. He knew it was an inconsistent attitude, but every time he tried to resolve it one way or the other his head refused to work.

  It was easiest to believe that the kids had misunderstood something.

  So he would go to the city, which seemed easy enough as long as his present captors could be persuaded to go elsewhere, and maybe something could be done about the other captive. Fyn’s general background doomed him to a certain naivety; it also inclined him to unhesitating action once he had decided what had to be done. There was only one thing to wait for, and that should come before they reached the jail.

  It did. They were long out of sight of the bay — unlike Bones’ captors a few hours later, this group had gone to the west of the low hills near the base of the Canton peninsula — so moonrise itself could not be seen; but the sky framing the high ground to their left gradually brightened, and at last Earrin felt that he could travel without actual disaster.

  “Nearly there?” he asked.

  “A couple of hundred meters,” came an answer.

  “You’ll see it when we get by that patch of brush.”

  They did. As might have been foreseen by anyone familiar with jail construction, they were near the bottom of a small gully, and as usual its brook had been applied to the arrangement of an air lock. Details were a little different; the stream seemed to run right under the building, and he wondered for a moment whether this one had two locks. He did not waste time trying to find out.