"Too big to step on." Omar laughed in his ba.s.s voice. "In bare feet, anyway."

Up close you could see the russet-and-gold diamond pattern on the pulsating oval of the thing's body.

"Protective coloration," Dmitri said. "It evolved with its host. Beautiful adaptation!"

"Beautiful?" Beth said, sounding sick.

Despite its apparent lack of eyes or other sense organs, the parasite was making a beeline for the shivering Triad, who stared at it as if mesmerized. It dragged itself along on its threadlike legs, the obscene sucking tube extended.

"Here's the hoe!" somebody yelled. w.a.n.g came puffing up with the garden tool and handed it to Omar.

"I can't watch," Beth said, turning away.

Omar raised the hoe to strike, when suddenly an ear-splitting whistle came from Triad, like the one she'd emitted when Tetrachord died.

Everybody turned to stare. Omar paused at the top of his swing to look around then braced his thick legs to bring the hoe down.

All at once everything clicked for Jameson. "Stop!" he yelled.

He hurled himself forward, one shoulder low, and caught Omar behind the knees. The two of them went tumbling end over end in the low gravity. The hoe went spinning out of Omar's grip.

Jameson picked himself up. "Sorry," he said, and extended a hand to help Omar to his feet.

Omar dusted himself off. "What the h.e.l.l was that all about?" he rumbled from somewhere inside his ma.s.sive chest. He seemed more puzzled than angry.

Jameson turned to make sure the parasite was all right. It had covered another ten inches in its grublike progress toward Triad, who shrank against the cage wall in a shivering paralysis.

Overcoming his repugnance, he bent and scooped it up in his hand. It was not slimy, as he had expected. It was warm and dry to the touch. It writhed and contracted in his palm, its threadlike legs clinging.

Triad made a faint wheezing sound. The others looked at Jameson with incomprehension or revulsion, except for Dmitri, whose face was expectant.

"This isn't a parasite," Jameson told them. "It's the other half of the Cygnan race."

"A parasitic male!" Dmitri said, turning the squirming creature over in his hand. "Of course! Why didn't I think of it?"

Over at the sloping wall, a few of the braver young men were restraining Triad, who was making weak, uncoordinated attempts to get to Jameson and Dmitri. Most of the diminished human colony was there, including Janet Lemieux, who had left a sedated Boyle in the care of a couple of volunteers. Ruiz had already regained consciousness with the help of a stimulant she'd given him, and though he hadn't yet tried to sit up, he was watching with lively interest.

"The Cygnans are all females," Jameson said. "The ones we've been thinking of as Cygnans, I mean.

What fooled me was the way they behave like courting couples. And the personality differences, and the fact that one was bigger and stronger than the other. If they've got to pair off to reproduce, I suppose it's natural that a weaker would tend to gravitate toward a stronger."

Dmitri nodded in agreement. "Not only natural-it's a survival mechanism for the species."

"What are you twotalking about?" Liz cried plaintively.

Dmitri laughed with sheer enjoyment. "These little males are just nonsentient vegetables," he said. "The Cygnans exchange them like engagement rings. Why didn't I see it? It took a rocket jockey like Tod here to point it out to me."

"But that thing in your hand doesn't look anything like a Cygnan," Omar objected. "It's more like an insect."

"Ah, but itdoes! " Dmitri said. "Same body structure-but the legs have atrophied because it needs them only for clinging, and the 'head' has regressed to its only function: to suck blood. No eyes, because a parasite doesn't need them, and if I dissected it I would find no digestive organs, because it gets its meals predigested. But the gonads, you can be sure, are well developed, as they are in all parasites. It is perfectly adapted to its way of life."

"What a filthy thing!" Beth said.

"Filthy?" Dmitri said, in genuine puzzlement. "Perhaps to us. To the Cygnans, perfectly natural. Nature always provides rewards to encourage reproduction-rewards in the form of pleasure, or at least release from compulsion." He nodded toward the struggling Triad, whose body contractions had grown rhythmic and violent. "That poor creature is in torment."

"But a parasitic mate!" Liz said. "Isn't that a bit farfetched?"

"There are any number of terrestrial examples," Dmitri said. "Trichosomoides cra.s.sicauda. It's a parasitic worm, like the Cygnans' distant ancestors. The male lives as a parasite within the uterus of its own mate.Edryolychnus . It's a deep-sea fish, very ugly. The male's a tiny appendage that attaches itself to the female early in life. Its eyes and other sense organs atrophy. Its blood vessels fuse with hers. I could go on."

"Strange way to perpetuate a species," Omar said.

"No stranger than ours. Males aren't very important in the scheme of things. They're just a mechanism for exchanging gametes. Female spiderseat their mates when they've finished their job. This thing in my hand is a gene package, not a lover. A Cygnan's emotional equivalent of a mate is the other female she trades males with."

Jameson became thoughtful. "Dmitri, how would it work biologically?"

Dmitri looked around happily. "There's an almost precise, terrestrial a.n.a.logy. A mite that's parasitic on moths:Lasioseius lacunosus . About one egg in twenty hatches as a male. The male is born first. That's so it can be an obstetrician for its sisters. It helps in the birth of the females by pulling them out of the mother's body. It lives as an ecoparasite with the mother for a brief time-it can't survive removal itself.

But before its sisters leave home, it impregnates them."

"But the Cygnan male doesn't impregnate itsown sister?" Jameson said.

"No, it simply becomes a parasite on her. Let's say it works like this. Suppose the Cygnans have multiple births, or hatchings, or buddings, or whatever. The male can't survive on its own, any more than Lasioseius lacunosus can. It must immediately hook itself into the bloodstream of one of its much larger sisters or die. The attachment of a first male probably stimulates production of a hormone or chemical trigger that prevents the other male siblings from implanting themselves-"

"The way an ovum becomes impervious to other sperm after the first one reaches it," Janet said, looking up from her work of bandaging Ruiz's head.

"Yes, yes," Dmitri said impatiently. "At any rate, it's the fittest that tend to survive."

"The courtship mechanism..." Jameson prompted.

Dmitri nodded. "What you call 'courtship' is two females pairing of and eventually exchanging their parasitic males. It must be as charged with emotion for them as s.e.x is for humans. The exchange is an evolutionary survival mechanism which prevents inbreeding. Presumably there's a hormone or body-chemistry block which ordinarily prevents a parasite from impregnating its sister-host. The courtship ritual, on the other hand, must release pheromones-repare the endocrine systems of both the hosts and the parasites to accept the switch, just as a foreplay prepares both human s.e.xes for s.e.x."

Jameson's eyes strayed toward Triad. The involuntary contractions of her body looked as if they were causing her physical pain. With each wave her rubbery body compressed by a third, then stretched out again like taffy. He was unable to imagine what she was feeling but clearly she was in the grip of a powerful biological imperative.

Her own tiny brother was already within the body of the dead Tetrachord, presumably dead or dying itself. The other half of the exchange must have been interrupted by the alarm. The squirming thing in Dmitri's hand was animated by its own biological imperative. If it failed to make contact with Triad soon, then the union of Tetrachord and Triad would produce no young.

Did Cygnans mate for life?

One of the Struggle Brigade stalwarts, a sinewy fellow with close-set eyes and bristly black hair brushed forward over his forehead, had retrieved the hoe and was prodding Triad with the handle. Jameson reached him in three swift strides.

"Stop that!" he said, and s.n.a.t.c.hed the hoe from the startled man. He tossed it down the slope as far as he could throw it. The Cygnan, in her private misery, shuddered. The sounds she was making were nonhuman, but to Jameson's acclimatized ears they were piteous nevertheless.

Hating himself for what he was doing, he got down on one knee and said, in his broken-chord Cygnanese, "Triad, I talk. Do you hear?"

Dmitri broke off his lecture. He started forward. "Stay where you are," Jameson said sharply. Dmitri stopped. The other people fell silent and watched Jameson.

The cl.u.s.tered eye polyps quivered and stretched in Jameson's direction. It was like looking into three orange-rimmed inkwells.

"I hear, Ja-me-son," the Cygnan trilled. "Give me the little brother."

"Not yet. You must help me leave this place."

"Jameson and his sisters are a wrongness in the sight of the mother-within-herself. You have stopped Tetrachord at the time of her (?)"

Jameson didn't recognize the last ideogram, but Triad, despite her distress, had made an effort to put the rest of her message in terms he could understand. "Stopped" was the term for a damaged piece of machinery. "Wrongness" was the word for "mistake" that had cropped up so frequently during his language lessons.

"What is she saying?" Dmitri asked eagerly.

"She's saying that we're abominations in the sight of her deity because we murdered her mate," Jameson said.

Beth made an indignant noise. "What about the peoplethey killed? And the Jovians and the other life forms they've exterminated? I suppose that if we don't have six legs, we don't count!"

"No," Jameson said. "We don't." He turned back to Triad. "The sisters who... stopped... Tetrachord are a wrongness to Jameson and his other sisters too."

Another contractile spasm squeezed the Cygnan, squashing her. When it pa.s.sed, the three eyestalks fixed on Jameson again, and the mouth centered among them opened like a pitcher plant. "Give me the little brother."

"No. You must help me leave."

"You are a wrongness. Like the other two-legs."

Jameson had no time to decide what that meant, because the Cygnan was fumbling among her pouches.

She extracted a short curving instrument that looked like a section of thick gold bracelet with little wheels set along its edges.

"Watch out!" somebody yelled. "It may be a weapon."

"I don't think so," Jameson said. "I think it's a key."

Triad dragged herself over to the gate. The humans made way for her. She clamped the gold bangle on the thick disk that contained the lock mechanism. The curves matched, and the wheels fit into a pair of grooves that ran around the outer rim.

She whistled, a complex roulade of chromatic phrases, and the section of bracelet crept along the grooves under its own power, or power provided from within the lock mechanism. It disappeared under the edge of the disk, and the whole wagon-wheel-sized a.s.sembly lifted. The gate slid open smoothly.

Jameson reached underneath and retrieved the device. "For opening cages from the inside," he said.

"The animals could never figure out how to use it."

Everybody had shrunk away from the opening as if it were dangerous. n.o.body seemed anxious to leave. Jameson turned to Dmitri. "Put it down. Gently."

Dmitri set the squamous little creature down on the floor of the cage. It humped its broad back. The sucking tube that was its head waved from side to side, seeking. It homed in on Triad and pulled itself along on its feeble legs, like an injured beetle.

Ruiz spoke up for the first time. Under the bandaged head, some color had returned to his lined face.

"They couldn't reproduce at their one-gravity acceleration, could they? No population growth until their ships are coasting or parked."

Jameson nodded at him. "No. And if we ever get back home, we can tell them the Cygnans won't be interested in settling on Earth, either."

The tiny male had reached Triad. It crawled blindly over the surface of her body. Her hide twitched. As Jameson watched, the tightly wrapped petals of the structure that looked like her tail parted and unpeeled. They spread all the way open like a blooming orchid. The little parasite crept inside like a bee looking for nectar, squeezing past the inward-pointing spines that, like a lobster trap, would prevent it from ever leaving again.

Cygnansdid mate for life. Even when their inamorata was dead.

The petals of the tail closed tight again. There was only a drop of thin orange serum trembling at the tip.

The rippling contractions of Triad's tubular body died away and stopped. The rings of muscle relaxed.

She lay limp and unmoving.

Jameson rubbed his knuckles over his eyes. He felt tired. It had been a long day for everybody.

"Some of you pick her up and get her out of sight in one of those tents," he said. "Go easy with her. And I'll want a detail to get the body of the other Cygnan out of sight. I don't know how long it will be before other Cygnans come to check, but if they don't see anything obvious, it may buy us some time."

Captain Hsieh drafted some volunteers and got Tetrachord's headless body inside the compound. They wrapped it in one of the precious blankets and covered it with rubble.

Jameson looked up at the winding observation tubes, frosty in the subdued light. In not too many hours, they would be filled with sightseeing Cygnans.

He turned to face the others. "All right," he said. "Who's going with me?"

Chapter 26.

"Here's all the food I could get together," Liz Becque said apologetically. "And there's about three gallons of drinking water in those cans and jugs. You couldn't carry much more than that. You'll have to depend on finding water along the way."

Jameson examined the supplies spread out across the pokes that Liz had improvised from squares of sheeting. It included all the canned and packaged food that Klein had overlooked, and some pressed bars of a fish-and-wingbean pemmican that she'd made from the leftover supper rations.

"You may not get fed in the morning," he warned. "Triad won't be in any shape to get the zoo routine back to normal."

"It's all right. We'll go hungry tomorrow. It's the least we can do."

Jameson began to tie up the bundles. He became aware of Omar Tuttle standing nearby, shuffling his big feet.

"I'm sorry, Tod," Omar said. "I'd go with you, but I'd better stay and look after Liz. The baby could come any time." He avoided meeting Jameson's eyes.

"Okay," Jameson said. "Don't worry about it." He went on tying up the bundles, and after awhile Omar went away.

He couldn't blame Omar. He'd told them all himself that there was little chance of catching up with Klein before the alerted Cygnans intercepted him, or of doing anything useful if he did. Klein had a small army with him. Armed.

"Don't go, then," Beth Oliver had said reasonably. "Let the Cygnans catch them. You'll only make things worse for us."

Pierce had said: "All you'll accomplish is to be brought back here anyway, and that's if you'relucky .

n.o.body shoots zoo animals. But you shoot mad dogs that are running around loose."

Janet Lemieux had said: "We need you here, Tod, Captain Boyle's going to need somebody to back him up. Otherwise the Chinese will control things. And you're the only one who can talk to the Cygnans."

What it all boiled down to was that everybody had an excuse for not going. Pierce, sheepishly displaying the arm broken during capture. Liz with her indisputable pregnancy. Omar, with his surrogate pregnancy.