The Nitrogen Fix

XIX Mystery, Metallic

Once out of sight below the surface, Bones made straight out from the shore for a couple of hundred meters. The smaller unit was a helpless burden, but as they travelled, they transferred ideas.

There was no question of total destruction; vital organs of the Observer units were too well decentralized for such injuries to be fatal. Fairly complete dissection, or incineration, would have been needed for that.

They reached a large patch o marine weed, and Bones left the other there to eat and heal. The idea was that it would remain for two full days before acting on its own; if possible, the larger unit would return with newer knowledge by that time.

The next goal was the raft. This must be done quickly, too, the Observer reflected; the newcomers could be expected to do something about the buds as quickly as possible. It seemed likely that Rembert would have relaxed his attention now that his friends had arrived, but it would be necessary to check carefully — yes, there was a human figure wading shoreward from the raft. Bones took the chance of emerging briefly at the seaward end of the vessel to make sure that no one else was on deck. A second or two later the odd head came up into the tent.

The children were still asleep, in spite of the noise on the beach. The larger ones would obviously not know the gesture language; whether little Danna could be made to understand the situation, and communicate it in time to the others, was a matter for worry. Bones had known the child’s limitations long before the reason for them had become clear.

Without climbing into the tent-even standing on the bottom, the Observer’s head nearly reached its top-Bones reached into Danna’s nest and gently pressed her shoulder. It was the standard please-pay-attention symbol, which one could hope would get through to the sleeping mind. The four fingers at the end of the long tentacle squeezed, and waited; squeezed again; again.

The noise ashore grew louder, and Bones swivelled an eyeball in that direction. There seemed to be no motion toward the raft, but the people were now so closely grouped together that action of individuals could not be made out even by Observer eyesight.

Another squeeze on the tiny shoulder brought results. Danna sat up, rubbed her eyes, and looked calmly up at her nonhuman friend.

“Where are Mother and Dad?” A tentacle gestured shoreward; the child looked that way and nodded. She did not seem frightened at the bustle, and turned back to Bones. “Are they all right?

What’s happening?” The observer did not think of hiding any information, but gestured as swiftly as possible.

“I can’t tell whether your parents are all right. The other people are the ones your mother ran from last night, and their friends. She thinks they want to take you from her, and hurt you unless she does what they want. You and these other small ones will have to get your masks on and come with me. Take all the air you can carry. I will take you to one of the tents across the bay, where these people can’t get to you. Wake up the others and explain to them as quickly as you can.”

The first part of this instruction was easy to carry out, but convincing the other children that theyshould go anywhere with the strange giant was quite another matter. Since Danna was so obviously on friendly terms with it they were not actually afraid — or at least, didn’t want to show fear in front of their younger companion — but going into the sea where eyes were so little use made both of them uneasy.

Both, fortunately, had heard enough the night before to make them afraid of the Hemenway group — Ray in particular recalled the incident at the other jail; but they agreed to go only after Danna had convinced them that travelling in the water with Bones was fun.

Even then they were not really enthusiastic, until an emphatic tentacle gesture toward the shore directed their attention to the fact that people were wading toward them. Then all reached for their breathing equipment.

Danna, true to her training, checked everyone’s mask and cartridges before they entered the water, though the others were becoming uneasy as the crowd approached.

“All right,” the little girl said finally. “Bones will hold on to you, and I’ll hold onto him — I know how, but you might get pulled off when he goes fast. Hold those extra cartridges carefully, remember. Let’s go.” Danna had gestured briefly to Bones that he was to keep hold of the others, and within a few seconds the group was away from the raft and, presumably, safe from the delinquents.

Ray and Betty were tucked under a fin on each side, held firmly by the long tentacles; Danna was pressed against the dorsal surface of the fishlike form holding firmly to the roots of the same limbs, just below Bones’ eyes.

The Observer was slowed, of course, by the triple burden, but was still travelling faster than any human being could swim. This did not make the children safe, however; they had to be brought to some place where they could breathe before their cartridges ran out, and all nearby places were likely to be visited by the enemy — another concept new to the Observer, but growing clearer with experience.

There were places where they would be safe — Earrin and Kahvi had several tents around the Boston area. Whether any of them could be reached with a safe air margin was very uncertain. Bones had no way of judging how long the supply carried by the children would last. Swimming speed was far below normal, and the trip even to the nearest would be long.

But there was a way to increase the speed, the Observer suddenly realized. The children were not aware of the sudden change of course as the idea burgeoned. Bones felt it was safe to pass between the Sayre islands and the mainland, since the fugitives would not be visible under water and there was no obvious reason for the Hillers to be crossing the channel. The error of this belief turned out to be unimportant, since no one was getting structural materials from the island at the time, and they got through the strait, around the north end of the peninsula, and into the bay where Kahvi had come ashore with her daughter. Danna recognized the spot where they landed, and showed the other children the things her mother had explained, while the Observer went to work.

The big mass of Newell tissue was still there. There were plenty of cordage growths. Bones, using the glass knife from Danna’s pouch, hacked off a slab with little trouble; it cut like the foamed plastic of long before which had inspired its genetic design. In a quarter of an hour it had been shaped roughly into a flat-topped boat, or perhaps a surfboard, and rigged with tow-lines for the Observer and holds for the passengers. At a gesture, the latter carried it to the water; another, and Danna laughed.

“Hold on tight,” he said to the others. “We’re going to go very fast.”

They did. They went around the north side of the Sayre islands, and turned east. The children weren’t quite sure whether to enjoy the experience or be frightened, but tiny Danna’s complete trust in Bones influenced the others.

They crossed the bay and passed south of Milton island. There was an air tent there, and Bones had debated using it; but the family had restocked it recently with a new variety of pseudolife, and had planned to treat it as an emergency site only until the changed system reached its new equilibrium.

It seemed safer to go on to Copper. This took them past the northern end of the Blue Hills, slightly southward, and after some ten kilometers of swimming, to the island which had once been Penn’s Hill.

The tent here was well established. It was the family home while they were gathering copper.

The source lay about a kilometer and a half to the east, under forty meters of water, at the site of the former Fore River shipyard. Here the copper-isolating pseudolife forms still delivered their nuggets,unimpressed by the fact that the still melting pole caps had rendered the area accessible only to Bones.

The Observer made sure the children entered the home, checked the water level of the air lock, helped Danna make sure of the condition of the air plants, watched her set out all their cartridges to charge, and left them eating happily. Leaving the boat drawn up where they had landed, Bones headed back at full speed toward the Canton shore.

Now completely unhampered, the powerful body made the distance in little more than ten minutes.

The last kilometer was done entirely submerged, but there was no difficulty in finding the raft, and the grotesque head emerged carefully into the air tent.

There was one person inside, working on the plants with ordinary Nomad attention to important business. She had her back to the hatch, and it was some seconds before she saw the Observer.

When she did, she made no sound or gesture, but there was no trouble divining the question in Kahvi Mikkonen’s mind. Bones answered it.

“Danna and the other children are at Copper, with all the air and food they need. I can get them back quickly when you wish. What has happened to Earrin?”

Kahvi frowned. “They are using him as they wanted to use the children. I still find it hard to believe that they’ll really — really kill him, but they say they will unless you come back and let them talk to you. I don’t see how they could expect you to go near them, after what they did a few hours ago; but they felt sure you’d come back to the raft, and told me to wait here and give you the message. I can’t ask you to give up your life for my Earrin, though; he can’t mean that much to you.”

Bones thought deeply. The concepts of death and killing were fairly clear now; it could be seen why they meant more to human beings than pain or even ignorance. As with Kahvi, the belief that Earrin’s life was really in danger from his own species could not really lodge in the Observer’s mind, though the emotional and conceptual block involved was of course different from the woman’s.

With the other Observer unit out of action for hours yet, Bones was unwilling to risk serious damage to this one, much less its complete destructions possibility, since the Hillers obviously had access to fire.

Once the other unit healed, of course, the Observer would certainly consider risking a body in the hands of people as long as the other could watch what occurred; but until then, Bones did not want to take serious chances.

“You say they just want to talk to me, now?” the native gestured at this point in its thoughts.

“That’s what they say. Maybe they mean it. They did want to find out how to kill you people, and maybe they’re satisfied about that, now. Maybe you can believe them.”

“Of course. Surely they must know their own intentions.”

The possibility of a deliberate lie had still not really dawned on the nonhuman mind. Kahvi, in view of recent experience, seriously considered trying to explain, but decided against it. It seemed easier to advise Bones to play things safely.

“You could talk to them, if all they really want is that,” she pointed out. “They may not all have the same ideas, remember; but if you stay out here on the raft, and have those who want to talk come out wading without their spears, they would know you could get away under water before they could possibly hurt you. Why don’t I suggest that to them? If they agree, we can believe that talk is really all they want.”

“That seems sensible,” replied the Observer. “I would like to talk to them, also. I know their theory about my responsibility for the air change; I can tell them this is wrong, and perhaps glean from their memories, if the speech code is really specific enough, some clues as to what did really happen. I realize there are no intact memories left even though there were human units here at the time, because of your incredibly indirect communication.”

“That seems to be about it,” admitted Kahvi, as far as I can make out from what these delinquents told Earrin and me. You realize, I hope, that your way of direct memory transfer between bodies is just as incredible to us; we think of your two units as two people.”

“That is coming to me. In any case, while I do know that one of your theories is wrong — I did not do anything to your air, and did not come here until it was as it is now — I do not know what is right, and wish very much to find out. It always seems to happen, on world after world. The air is always like thiswhen we arrive-otherwise we wouldn’t arrive — but close investigation always indicates that at some earlier time there was indeed much free oxygen. There always seems to have been life adapted to such a condition inevitably; oxygen is far too active to be in an atmosphere for long without life forms to maintain the supply.” Kahvi nodded; basic biochemistry was part of even Nomad education. “It seems reasonable to infer that the ordinary course of evolution eventually produced an organism, probably microscopic in size and rapidly reproducing, which oxidized nitrogen; but inference is of course not knowledge by itself.”

“You sometimes have to act as though it were,” the woman remarked.

“That seems to be true for you individuals,” admitted Bones. “You lack the time to let inferences accumulate and check against reality until they become knowledge. However that may be, the same change seems to have occurred on all the worlds I have seen. An organism develops which oxidizes nitrogen with free oxygen, and a new equilibrium is reached between the two — the one this world has now, with only a trace of free oxygen.

“The story is that men made the organism. We know they made many — most of the ones which keep us alive now are artificial,” Kahvi agreed.

“I can’t see, though, why they’d make one which destroyed the air, except by mistake; and how could anyone make such a mistake? They would have had to think, first, surely. That’s why most of the Nomads we know doubt that the world ever did have oxygen in its air.”

“It did,” Bones assured her. “I made the usual tests when I landed. There are no symbols in our mutual language to explain them, but I feel quite sure of that inference.” Kahvi of course accepted the statement, and thought deeply for some seconds. She had not forgotten her husband and daughter, but was hoping that this problem, if it could be solved, might affect relations with the group she now called the Delinquents.

“You must know,” she said at last, “what sort of life form does oxidize the nitrogen. Is it a pseudolife of the sort people made, or nitro-life like yours which is most of what grows now?”

‘It is nitro-life,” the Observer replied. “There are a large number of species. However, much of the pseudolife you use is of the same variety. It would seem possible that artificial life made by your people was indeed responsible for the change.”

“But pseudolife is so stable, and nitro-life mutates so easily.

“Which is why a single mistake on the part of your life technicians could have sufficed.”

“I’d hate to have Genda turn out to be right. She’s bad enough to listen to now,” Kahvi muttered.

Bones did not understand this in the least, and waited for something answerable. It came.

“You know how pseudolife is made — you could make it yourself.”

“Yes.”

“Could you make any of the kinds which oxidize nitrogen?”

“Yes.”

“Would it be more difficult than making other kinds, or might it happen by accident?”

“It could hardly happen by accident. All the organisms able to do this, on every world I remember, use one or another of four enzymes — you know what they are?”

“Of course. The symbol is plain enough; we’ve talked about such things in our own life systems.”

“Those enzymes use a very surprising metal.”

“What’s surprising about it?”

“We have not been able to learn why it is so widespread in every planet’s crust. It is one of the standing mysteries, which presents itself on world after world. It is a highly unreactive metal, which I would expect to find uncombined and highly localized. It should not be so thoroughly spread through a planet’s soil and crust that a microbe can count on finding enough of its atoms whenever it needs them for its personal chemistry. One hypothesis is that a scientific race used and scattered it, but there has been no way to tell; I have never found a use for it myself, except in the most limited quantities in the laboratory.

That is one reason I want to talk to these people of yours who seem to be somewhat scientific in nature.

They might have knowledge of their own, even if memories are gone.”

Kahvi had her doubts about this; she felt that she knew pretty accurately the scientific status of the Delinquents. Essentially, they had probably been playing with cultures and Evolution Plant enzymes on ahit-or-miss basis. However, that was Bones problem.

“What is this metal?” she asked. “Some obscure heavy element they never mentioned either in Surplus School or Citizen s Training, I suppose.”

“You know about it,” Bones replied. A handling tentacle reached out and touched the gold bracelet on her left wrist.