The Nitrogen Fix

by Hal Clement

  This Hiller was doing his own job and taking his own chances; good breath to him. Still, her job was to take care of Danna and Earrin.

  So she told herself as she swam back to the child, but she was uncomfortable about it. Not quite as uncomfortable as after she had lighted the fire, but queasy enough. Conflict-of-duty questions had been few for Kahvi Mikkonen since she had been a Nomad, and they bothered her. Maybe Earrin, when she found him or he got back to them, would be a help; he was the sort who could keep from worrying over things that couldn’t be mended. On the other hand, she might not be able to bring herself to tell him about the fire. He had been an understanding and tolerant teacher in the early months of her Nomad life — otherwise she would never have developed the affection for him which she had — but even he must have a limit somewhere, and lighting fires might be beyond it.

  With Danna swimming close beside her this time, Kahvi hugged the bottom closely as they moved away from the raft. She headed almost east for a time. She was not going to risk going between Sayreand the mainland; the water was deep enough, but there was the obvious risk of running into the search party on its way back from the island. Since they might also be intending to look over the smaller one farther north, there was at least a kilometer and a half to swim around this. Danna, her mother was sure, could make the distance as long as they went slowly enough. The water was warm enough so that even the little one’s big surface-to-volume ratio offered no risk of chilling. All Earth’s water was warm these days, except next to the still-vanishing pole caps. The acid seas had given off most of their dissolved carbon dioxide, and carbonate minerals were busily doing the same; greenhouse effect was warming the planet. Nitrogen dioxide, blocking some of the incoming radiation, was slowing the process, but where it would end no one could tell.

  Fortunately for general peace of mind, no human being left on the planet had any idea of the process; and it had not even occurred to Bones.

  By keeping in less than four meters of water, the two were able to contour-chase around the islands, but they were both extremely hungry by the time Kahvi judged they had come far enough. Danna had not yet learned how to eat under water, though the Nomad masks permitted this. The woman did not consider this a good time for a lesson in the art, since an error in coordination might have forced them to surface in order to get water out of Danna’s mask, so she had not eaten either.

  As it turned out, they had come rather farther than necessary. They came up at the mouth of the cove on the northwestern tip of the peninsula, here Bones had decided the night before not to attempt landing.

  Kahvi, aware that the searchers might have come this far but considering it most unlikely, chose to take the chance. The two swam ashore, got quickly out of sight in the dense vegetation, and settled down to eat.

  The sun was now well past the meridian. Danna was very tired from the swim, and Kahvi decided that time had to be taken to rest, though they would have to find a jail or some other oxygen source before too many hours. They didn’t build a nest this time; there was a fluff organism large enough to keep the small body off the ground, and the child curled up in this, while her mother scouted the area for useful plants. The peninsula, or at least this part of it, seemed to have been visited by people who had allowed many kinds of pseudolife to take hold; Kahvi wondered whether this had been intentional. She would have been much more certain if she had seen the one which Danna had found on Sayre. There were tissue producers of a dozen kinds at least; a gigantic block of the Newell material from which the Fyns made their raft floats, the transparent stuff which was used for roofs, even the highly specialized material from which breathing cartridges were loaded. At present, of course, this was empty; Danna, waking up at last, was able to pick up logs of it larger than herself. She amused herself throwing one of these around while her mother explained the uses of the different growths.

  “Do you think you could find these again if we wanted them?” Kahvi asked at length.

  The child looked thoughtful. “Where will we be when you ask? I don’t know where home is, right now.”

  Kahvi laughed. “Good for you! Mother wasn’t thinking, was she? Here, let me show you.” Even with air shortage threatening, the child had to learn, and a few minutes could be budgeted for a mapping lesson. Danna caught on quickly, and after a few minutes study of the diagrams Kahvi scratched in the earth, she was able to point out the direction to the raft and even give a fair description of how long it might take to get there.

  Very satisfied with themselves and each other, the two resumed their journey. There was only a small amount of food left. Kahvi rolled it into a single pack of tissue and fastened this to her harness. She was still fatigued, and even Danna had not slept very long; but the woman let the child straddle her shoulders, after readjusting cartridges and breathing lines to make room, and set off again a little west of south. The bulk of Great Blue Hill loomed three kilometers away in that direction, but she was using this as a guide rather than a goal. She planned to follow the ridge which led south along the peninsula — the same one which overlooked the anchorage — high enough to get a good view of the land in hope of spotting jails, but not big enough to be seen from the anchorage itself or the islands.

  The choice of route was unfortunate, since it led close to the fire site which Bones had found. Kahvi saw this, and once again decided that the search for air could be postponed a few more minutes toexamine this curiosity. The Bones trait was contagious, at least to intelligent people.

  The contents of the fire pit had now reduced themselves to white ash which would not have glowed visibly even at night, but some heat could still be felt. Kahvi realized as Bones had done that this must be the site of the fire which had imperilled the nearby jail. She also saw that the stone wall which had been around it must have been artificial, and had to examine it closely even though it was obviously not an oxygen source — at least not any longer. She put Danna down, advising her to rest, but made no mention of the danger of appearing at the top of the ridge.

  The child, tired as she still was, wanted to make sure that the ideas she had gotten from the map were right. If so, she judged, she would be able to see the raft from the elevation only a few dozen meters away; and without Kahvi’s noticing, she headed quietly in that direction. The vegetation here was too sparse to hide either from the view of the other, and the girl felt perfectly safe.

  Inevitably, she encountered the same bed of glass slivers which had trapped Bones. Her scream brought Kahvi on the run. Her reflexes were good, and she placed only one foot in the danger area; she managed to stop before the other was injured, and even held back the cry of pain which almost escaped her lips. She snatched up the child and retreated several meters, ignoring the agony in her left foot until she felt they had reached a safe distance from whatever was causing the pain.

  Then she put Danna down gently, sank to the ground herself, and fainted.

  XIII

  Peregrination, Painful

  It was pain that caused the faint, and pain that brought back consciousness; Kahvi was out of action only a few seconds. Danna’s shrieks had ceased, and the mother’s awakening was completed by the realization that the child had torn her mask off — it had interfered with the deep breaths needed for the cries. The little chest was still heaving, but the lips had already turned blue.

  Again Kahvi’s own pain was forgotten. She snatched up the discarded breathing gear, squeezed the bellows to empty it of outside air, replaced the mask on the child’s face, and pulled the bellows open again to fill it with straight oxygen from the cartridges. It was no longer possible to see the lips, but the convulsive gasping grew quieter and in a minute or so the still unconscious girl was breathing normally.

  Kahvi, her terror reduced to a bearable fear, examined her own foot. Like Bones, she had no trouble identifying the cause of the pain. In full sunlight the slivers were easy to see, and for the most part easy to withdraw. Their shape made them easy to get hold of, they were no
t simple, straight splinters, but caltrops, their four ten millimeter points directed tetrahedrally. No matter how they landed on the ground, one point was always upward. The other three provided a good stand on the ground and, fortunately, a good handle for pulling the things out where they protruded from the skin, provided they had not broken off. Two or three had done this, and Kahvi was still working on the last of these when Danna began to regain consciousness.

  The mother instantly turned her attention to relieving the child’s pain. Pulling out the Hillerspikes, as the woman had mentally dubbed them, did not hurt very much; the real torture came when they were pushed in. Danna, once she was fully conscious and had been made to understand what had happened, was able to help with the removal.

  She had been far more seriously hurt than her mother, however. Both feet had gotten into the trapped area, and she had then fallen down, so that both hands and much of her right arm, leg, and side were involved. They removed nearly forty of the things; Kahvi’s foot had contained only seven.

  Danna, with her mother’s help, got to her feet at last and walked gingerly around. There were still tears behind her mask, but the sobbing had stopped. It was obvious that she was still in pain, but the pride of self-sufficiency and self-command which her parents had tried so hard to instill was taking over.

  “Can you walk all right, now?” Kahvi asked.

  Danna gave an affirmative nod. “Good. I’ll still carry you for a while, because I know you’re tired and your feet are sore, but I had to be sure that you can go by yourself if you have to. Now, remember;We’re looking for a place to get air — air and food, but mostly air. You know the jail. What we’ll most likely find is something that looks like that, though maybe bigger or smaller. It will probably be on a river — ”

  That word had to be explained. So did the reason why they were travelling near the top of the ridge when what they sought should be in a valley. So did what they would have to do if they didn’t find a jail.

  It was some minutes before Kahvi could swing the little one up to her shoulders again and resume their journey.

  She was rather proud of herself: It had been a temptation to denounce the Hillers as a tribe of subhuman, torturing savages and murderers. Her anger at the people who had set out those hellish bits of glass was still at white heat, but she had not passed it on to her daughter — though she knew that if she met a Hiller at this moment her normal hangups against violence might not hold up. There would actually be pleasure in tearing the mask from his — or her — face and throwing it as far as possible, and watching the creature run after it, and stagger, and fall, and die as Danna almost had. It might even be pleasant to watch such a person roll on ground covered with the same bits of glass he had obviously intended for use against other people. To hear him shriek as Danna had shrieked — to watch him tear off his own mask in agony, as her own little one had done — Kahvi suddenly had to put the child down and open the eating flap of her mask. For two or three minutes she was very sick, while the child watched in uncomprehending sympathy.

  When she stood up again, the mask once more in place, her mind as well as her stomach had been cleared, but she felt depressed. She usually enjoyed looking at things — at hills and trees and plants, at clouds and sky; she had never seen a green Earth, but regarded the multicolored one she knew as beautiful. Now, however, she could not appreciate it. It was not just the realization that habits of human behavior formed such a thin skin over antihuman urges; there was more material fear. She could not appreciate any beauty as she walked. Travelling was not just walking; every step had to be taken with care. She was unlikely to see the Hiller-spikes even if she walked bent over with her face as close as possible to the ground. This meant that every step had to be taken cautiously, feeling for the slightest twinge of pain, ready to pull back at once before weight was put on the foot.

  She had no way of telling where the Hillers might have set other traps. The only obvious quality about the first one was that it lay between the fire site and the raft. Had it been intended to keep people — barefooted people — away from the fire, or from the structure which had been destroyed by the fire? If so, there might be no more traps; but there was no way to be sure, and she could take no risks — certainly not with Danna; so she went very, very slowly. The delay was irritating, and the irritation gradually brought back the subhuman thoughts about Hillers. .

  They followed more nearly the way Bones had been carried than the route taken by her husband.

  Hemenway, the nearest of the Blue Hills, was the eminence Kahvi was now taking as a reference point.

  She knew that the city extended underground from Little Blue Hill on the west to Hemenway and Houghton on the east; unlike her husband, she knew the location of many of the air locks, and knew that she could certainly find one of these if no jail turned up — though she certainly hoped to renew air and food somewhere outside the city.

  She might, if these had been her only object, have headed for the west side of the city where she did know many of the jails; but she had heard enough while eavesdropping to make Hemenway her goal.

  They had wanted to take Earrin there; he had apparently escaped on the way there; and while he might have gone anywhere afterward that still seemed the best place to start looking for him. Unfortunately, none of the contingency plans they had so often amused themselves by concocting had managed to cover any situation much like this one; and well as she knew him, Kahvi had been quite unable to guess what her husband might now be up to.

  The top of Hemenway was about a kilometer and a half from the fire site and glass trap, so there was in fact little chance to get far from Earrin’s actual trail. They encountered the jail to which her husband’s captors had been leading him, and after some hesitation Kahvi checked the interior, found it empty, and rested there briefly; but of course there was no sign of Earrin in the building.

  They had passed the point where he had escaped but Kahvi had none of the experience needed torecognize any clues which might have been on the ground.

  She had no hesitation in eating from the food growing in the jail, or in exchanging her used cartridges for full ones. The rest was shorter than either of them liked, and Danna could not see why they had to go on after finding the food and air her mother had said they needed. She was outspoken about this, and Kahvi had to take more time to explain.

  “We can’t stay here, because some of the City people come here sometimes. Remember, we don’t want them to find you.”

  “But why can’t we hide a little way off, and come back whenever we need air?”

  “Maybe we will, but there’s something else we want to find.”

  “What’s that?”

  “Your father. I think these people may have taken him, so we’ll have to get him back just as he and I would get you back if they took you.” Danna accepted this as reasonable, to her mother’s relief; she had gotten enough rest to be more cheerful, even if it wasn’t all she wanted. She checked and donned her outdoor gear with no more complaint, and even grinned with pride when her mother approved the check.

  The way now led up Hemenway slope. The sun had set, though the sky was not yet completely dark.

  A few bright stars could be seen between slowly drifting clouds. They were still traveling very slowly as Kahvi continued to feel her way.

  Danna was walking now, but had been warned to stay behind her mother; with the memory of the glass still fresh and its pain still in her body, the child was quite willing to obey.

  Kahvi knew of an air lock on this side of Hemenway, and was making their way toward it.

  She had decided that there was a good chance of Earrin’s being inside the city. There would have been no chance for him to get back to the raft, and no evidence that he had tried. He had either stayed free and gone to a jail or the city for air, or been recaptured and brought to Hemenway as had apparently been the original Hiller intention.

  In the old days, the citizens of Great Blue Hill had very seldo
m gone outdoors after dark. This seemed to have changed now, and she didn’t dare approach the lock as casually as she might have done earlier. Since she had to travel so slowly anyway, the extra care wasn’t as much nuisance as it might have been.

  Once in sight of the lock pool, in fact, she decided to wait for a time to see whether any of these young people who seemed to go out a lot at night might be around, so she settled down in the center of a clump of bushes which provided materials for a hastily-made nest. Danna made no objection to going to sleep; there was nothing which interested her in the surrounding darkness.

  Kahvi, in spite of her intention to keep watch, might have followed her daughter’s example, but they had been there only a few minutes when sounds came from the nearby air lock. The moon was not up yet, but part of the pool reflected starlit sky, and the reflection was now broken by ripples and by dimly silhouetted human figures rising from the water. They were not showing any particular caution; there was an occasional splash, and some of them were talking. There was nothing in Kahvi’s large collection of highly virtuous hangups which prohibited listening; information, including information on what other people were doing and planned to do, was necessary for life. She listened: “D’you suppose it’s gotten away yet?”

  “Of course not. Les was watching; he’d have come to tell us if it had started anything he couldn’t take care of himself, or if it had gotten loose before he could stop it. Besides, what could it do? It only tried the things we expected.”

  “And what,” asked a female voice, “gives you the idea that it couldn’t think of things we haven’t? Of course it tried the obvious ones first. Sometimes they work. Remember how those two got away inside — and we still don’t know where the other one is, you know.”