The Nitrogen Fix

by Hal Clement

  It took several minutes for the spreading glow to reach any of the blaster plants, and she was well to the north before the first crimson flash illuminated the view and the accompanying heavy thud reached her ears. She promptly dropped flat again and wriggled toward the top of the ridge bringing her head up with as much care as before.

  The people might not be so stupid as to look only at the fire. She was recovering her self-control,though she felt nauseated.

  Both workers were running toward the jail, calling out loudly. As far as Kahvi could tell at that distance neither was looking back. She still played it safe, however, crawling down toward the water.

  She had farther to go than the runners, and they got to the jail before she reached the water. The moment they disappeared into the lock pool, Kahvi got to her feet and ran as fast as she could — she was safely submerged before the other oxygen-wasters had donned gear and come outside.

  The moon was still visible after a fashion in spite of the brightening sky. Its image was distorted and swung back and forth by the swell, but it gave some guide to direction. Kahvi stayed below the surface — entirely-charged breathing cartridges were much denser than water, and she needed no effort to stay down — until she felt sure that she had swum farther out than the raft. Then, still very carefully, she raised her head. The swell alternately lifted and lowered her nearly a meter, but she caught glimpses of shore and raft.

  She was still well north of the latter, and somewhat farther from shore. She was tempted to stay on the surface for easier navigation, but the six Hillers were now outside the jail. Even though they were moving rapidly toward the fire — the crimson glow and rising column of smoke made her feel sick again for a moment — and seemed to be paying no attention to any other direction, Kahvi decided to play it safe and submerged again. The next time she came up to check she was almost directly out from the raft, about a hundred meters, and people were all out of sight. She finished her journey on the surface until she had to go down again to get to the entry hatchway. She climbed in as quietly as she could, but it wasn’t quietly enough; the child felt the change in motion of the floats.

  “Mother, is that you? Where were you? There’s another fire, and I’m scared. Should we go out with the buckets again?”

  “No, dear. This is just a little fire, and it won’t come close. You may watch it or go back to sleep, whichever you want.”

  “Which will you do?”

  “I’ll watch for a while. Do you want to come over here with me?”

  There was no verbal answer, but the floats changed their rhythm again and a moment later her daughter’s tiny form was cuddled against her.

  No more words were necessary, and Kahvi carefully refrained from using any. Danna helped remove her mother’s outdoor gear without asking again where she had been — after all, there was nothing unusual about either of her parents’ going out to check anchors or other things even at night.

  Several silent minutes passed, and Kahvi began to hope that the little one had gone back to sleep.

  But she hadn’t. She saw the figures in the growing light as quickly as her mother, and felt Kahvi stiffen at the sight.

  “Who are those people, Mother? Are they coming here?”

  “They may be. Get your outdoor gear on, Dan, but don’t connect cartridges until they really come into the water. Be quick.”

  X

  Contretemps, Confused

  It was brighter after passing the air lock. The lighting system of the city could not compete with daylight, but was better than moon and comet together. Earrin had intended to emerge from the water very carefully, but realized in time that this would be more likely to attract attention than a casual entrance. As it happened, his attempt at nonchalance was wasted, since no one was inside the cavern which held the air lock. This was hardly surprising in view of the hour, but Fyn still felt relieved.

  That lasted for only a moment, until he suddenly realized that he had no real plan of action. The two main needs were obvious: he had come to find the captive native, and he would of course have to get his breathing cartridges recharged.

  The latter would take care of itself if he could leave them exposed to city air for enough hours, but itwould be better to get them into the full-pressure oxygen of a life-support bubble. How the captive could be found when Fyn had not the slightest knowledge of the city’s layout, beyond occasional details mentioned by his wife, was far from obvious. Earrin began to suspect that he was not being very realistic, or even very sensible. Presumably the life support area would be at the top of the city, since it would need sunlight — Kahvi had, in fact, said as much. About all that could be done, therefore, was to take every opportunity he could find of going upward. He started along the first corridor which caught his eye, out of the dozen which opened into the cave.

  Within fifteen minutes he was hopelessly lost. The tunnels were not straight, as Bones was to discover some hours later. However, he kept on. Presumably the higher he got, the smaller would be the city area; it was quite likely that life-support took up the whole top level. He was not using his own air — this would have bothered his conscience as a rule, but at the moment the city owed him — and there were plenty of hours available.

  It was not entirely luck which kept him from being identified as an intruder for all those hours. He had come in at a seldom-used lock above the heavily populated levels; and even though most of the people lived and worked out of sight of the sun, the city was mainly active by day and asleep at night. There was nothing like a regular police or guard force. Like the Nomads, the citizens had to follow rather strict natural laws in order to survive, though the laws were not quite the same as those needed outdoors. The city-dwellers had their own standards of righteousness, and a few generations of enforcing these by firmly Nomadding offenders, combined with the fact that it was difficult for social parasites to get away with their life-style for very long in such a confined area, had made police activity superfluous. There were exceptions, of course; crime waves followed by spells of vigilante activity occurred more or less regularly, but Fyn had made his entrance at a relatively safe part of the cycle.

  In better light, his outdoor coloration might have caught attention. However, the pseudolife plates which provided illumination were dim by electrical age standards even where they were regularly fed and watered. Elsewhere they sufficed to keep pedestrians from collision.

  Fyn, therefore, had no trouble travelling, even though he had no idea where he was going horizontally. It took him more than an hour to find a stairway going up, though he had encountered two heading downward in that time. He judged, correctly, that this was support for his higher-the-smaller hypothesis. The stairway took him up some twenty meters, passing several levels, before it ended and he had to seek another. This didn’t take so long to find, but gained him much less height. It did gain him, though he didn’t realize it for some time, a follower; a slender, tentacled form which looked like a fish walking on its tail.

  He never knew just how long it took him to find the air center, but the sun was high when he finally did. Golden daylight, visible at a distance along a new corridor, was in fact the final guide. By this time he was meeting people fairly often, but no one paid him much attention in the biolit tunnels. His act of nonchalance had been perfected by practice, and he no longer felt the urge to duck into a side tunnel whenever someone appeared ahead. His follower was doing this, so far in time to have avoided notice.

  There was more system to these upper corridors; the Observer had worked it out, and succeeded in getting back on Earrin’s trail each time it had been necessary to hide. Actually the being did not regard the concealment as really essential, but wanted to keep track of Fyn without compromising him.

  With the increasing number of people around, Earrin was feeling less and less sure of himself as the minutes wore on. When the sunlight appeared ahead, his spirits revived a little; this had to be the air and food supply region, and he could recharge both air
cartridges and stomach in a short time if he weren’t recognized in the brighter light. How many attendants would there be on hand? How preoccupied would they be with their routine work? Could anyone come in, eat, and exchange or renew cartridges without any formality? Kahvi had never told him.

  His tension mounted again as he approached the daylit end of the tunnel and a figure appeared there a few meters ahead of him. Fortunately this one, a woman who looked a good deal older than Kahvi, had just been in full sunlight and for the moment could see scarcely anything. She did detect Earrin’s presence and nodded indifferently as she passed him, but that was all. That left the man five meters from daylight with no obstacles in sight.He did not, however, reach full sunlight just then. A sudden shout of surprise in a female voice sounded from behind him and caused him to swing about sharply. A few meters away was the woman who had just passed him; about as far beyond her, another shape was disappearing into a side passageway. The Observer had run out of luck. Fyn, his eyesight already affected by the brightness he had been approaching, was not sure of details, but he saw enough to tell why the woman had shrieked.

  His first impulse was to get out of sight himself, and he almost turned back toward the end of the tunnel.

  However, the woman had already seen him; and if there were people in the plant room who had also heard her cry. .

  He came quickly down the tunnel to where the woman was standing. “What’s the trouble?” he asked, in a voice whose anxiety was not entirely feigned.

  “I saw something — one of the outside animals — duck into that side alley,” she replied, in a voice much calmer than the cry of a moment earlier.

  “How could that be possible?” asked Fyn. “How would one get in the city?”

  “Don’t be silly,” was the less than tactful reply.

  “They could get in through any air lock. The mayor insists we can’t watch them all and claims it’s dangerous to block any of them up. I say it is more dangerous to leave them open now that we don’t need them all. But what are we to do about this animal?”

  “Why do anything? What harm can he do?” asked Fyn in what he considered a calm and reasonable manner. The woman turned sharply and looked at him carefully for the first time.

  “Where were you brought up?” she snapped. “They’re not citizens, and have no right to the city’s air.

  Are you one of these liberal delinquents who claim there’s more than enough oxygen?”

  “But they don’t use air. They don’t breathe,” Earrin pointed out.

  “How would you know?” the woman peered more closely.

  “I work outside.” Earrin made the only possible answer, at the same time holding up his breathing mask.

  “And how would that tell you anything about the animals, unless — ” she paused, and appeared to forget her first anxiety for a moment. “Come back to the light with me.” She took him by the arm and marched him rapidly toward the end of the tunnel. Earrin, unused to such a forceful personality except when masked by Kahvi’s loving tact, and quite unable to employ violence against a person, went along.

  He was still trying to decide whether he should face recognition as a Nomad or jerk away, join Bones — who must have been following him after all, it seemed — and face only suspicion w hen they reached daylight. He could only come up with what he considered reasonable words.

  “How could they live outside if they had to breathe?” he asked. “I thought citizens, even if they stay indoors all the time, were supposed to know at least as much as Surplus kids.”

  “You can skip the insults,” was the answer as she tugged him along even faster. “You can’t tell me that there’s anything that doesn’t have to breathe somehow.”

  “But how do they — ” Earrin gave up. This was a Hiller, and Hillers thought differently, as Bones sometimes seemed to. Bones, however, was usually rational if one took the time to work out in detail what he was saying; this seemed different, somehow.

  Out in the sunlight the woman took one look at him.

  “I thought so. Nomad. I suppose you brought that animal in with you.”

  “No, Teacher.” Earrin was not being funny; old reflexes had been triggered. “It may have been following me, but I didn’t know about it.”

  The woman — a rather thin individual of middle height, with her hair largely gray but neither skin nor hair showing any trace of the yellow which went with outdoor life — seemed to accept the statement.

  Nomads, as was common knowledge, did not lie. “Have you seen it before?” she asked.

  “I have seen one before, quite often,” Fyn answered carefully. “I did not see this one clearly enough to be sure whether it is the same.” He felt a slight twinge of conscience, but was able to convince himself that this was not deceit; this might not be Bones, though the other was supposed to be a prisoner. “Shall we try to catch him and find out?”

  “You should get out of the city at once — you can’t say you aren’t breathing out air. Still, if you willpromise not to try to get away from me, and to help me if we do catch up with that thing, all right.”

  “I promise.” Fyn wanted, as badly as the Hiller woman did, to get a better look at the native. It seemed most probably that it was Bones, but the more Earrin thought, the more he felt that there had been something different about the fleetingly glimpsed figure.

  “All right. Come on.” The woman, again taking Fyn’s word at face value, led the way back into the tunnel. They approached the cross passage where the native had disappeared and looked around the corner. Nothing but dimly lit stone and darker doorways could be seen. They went along this, checking inside each room as they passed it. For thirty or forty meters there was no conversation; then the woman spoke again.

  “Why did you come into the city? Were you planning to steal something?”

  “What does that mean?”

  “Take something for your own without having made it or paid for it.”

  “No. I was looking for something, but not to take it.”

  “Not even air?” the woman sneered. Fyn was a little shocked at the question.

  “How can you steal air?” he asked. “I know you regard it as city property, but surely you wouldn’t keep it from anyone for that reason. Of course I would have recharged at your air center.” His voice made no secret of his feeling about the matter.

  “That is stealing. You have no right to do such a thing.”

  “I don’t agree. In the first place, you don’t keep air from anyone who needs it. In the second, some of your people made me go with them last night, and use air I would otherwise have replenished from my own source. I think I have a perfect right to a charge at your city’s expense. Those people owe it to me.”

  “They brought you into the city?”

  “No.” Fyn’s habitual truthfulness was in complete charge, though he had some doubt about telling the whole story to this Hiller. “They said they were going to, but I got away from them. They wanted me to do something I did not approve of. If I had gone home they could have caught me again easily, so I came here to recharge.”

  “And you just came in through the first air lock you found. No one stopped you?”

  “No one was around. It was night. I’ve been trying to find my way around here all day.” His interrogator looked at him shrewdly and, he thought, a little more sympathetically.

  “You might have charged up with more than air, then,” she remarked.

  “Of course. Food goes with air, anyway. Or doesn’t your food grow on — ”

  “Oh, yes. Well, maybe if you’re helpful with this animal we can supply you with some of both.”

  “You owe me some already, if there are any new varieties. I haven’t been paid for my cargo yet, and the payment was to be at least two new cultures for making air, food, or some structural material.” Earrin explained the situation in detail, still omitting mention of Bones and the Fyn family’s relations with the being. The woman seemed quite surprised.

&nbs
p; “I hadn’t heard of such arrangements being made with Nomads,” she said. “I know that people sometimes trade with them, and I’d heard that some people were careless enough of the rules to let new varieties of plant survive. I’m very surprised that such materials were actually used. I don’t see what anyone would want with copper or glass. I’ve seen a few tools made of the metal, and of course the roof of the air section has glass in it to let the sunlight in; but surely no one is going to build more air rooms.”

  “Glass can be used for tools, too,” the man pointed out, drawing his knife and handing it to her. She examined it with interest and returned it.

  Neither thought of any distinction between tool and weapon.

  “Well, I haven’t heard of any special want for either of them,” the woman finally repeated.

  “Come on, let’s find this creature. Wait — maybe one of us should go back to the stairway. There’s only one to this level. That will keep it from getting away. It could circle back and get there ahead of us if we don’t; there aren’t any dead ends in these tunnels. Again she had to clarify several of her terms to the Nomad.

  “I’m not sure I could find the stairway,” Earrin admitted. “if you think it should be watched, you’ll have to show me the way, or get some more help. Do you think you can take care of the animal if you catch itby yourself?”

  She was silent for a short time. “I don’t know,” she said at last. “Maybe we should stay together.”

  “I don’t believe it would hurt you. I’ve seen the one I mentioned often enough without ever having trouble with it. Of course, that woman with the group that had me last night was saying terrible things about them — that they ate their own children, and that sort of thing. Is that what bothers you?”

  “What woman? Was this the same group you were talking about? I never heard such a story in my life.”

  Again Fyn spent some time explaining, interrupting the search once more. For some reason, the woman now seemed even more upset than she had been at the first sight of the native. She was wearing a very perturbed expression when he had finished telling about the “Invaders” as described by his recent captors.