I said, "Their stomachs must be the chemical equivalent of a blast furnace; there doesn't seem to be anything they can't break down."

"All those teeth in the front end must have something to do with it," Ted pointed out.

"Sure," I agreed. "They cut the food into usable pieces, particles small enough to be dissolved-but in order to make use of that food, the stomach has to produce enzymes to break the complex molecules down into smaller, digestible ones. I'd like to know what kind of enzymes can handle such things as fingernail clippings, toothbrush bristles, canvas knapsacks and old videodisks. And I'd like to know what kind of stomach can produce such acids regularly without destroying itself in the process."

Ted looked at me, one eyebrow raised. "Are you going to dissect one and find out?"

I shook my head. "I tried it. They're almost impossible to kill. Chloroform hardly slows them down. All I wanted to do was put one to sleep for a while so I could examine it more closely and take some skin samples and sc.r.a.pings-no such luck. He ate the cotton pad with the chloroform on it."

Ted leaned forward; he put his elbows on the table and his face into his hands. He peered into the millipede cage with a bored, almost weary expression. He was even too tired to joke. The best he could manage was sarcasm. He said, "I dunno. Maybe they're all hypoglycemic......"

I turned to look at him. "That's not bad. . . ."

"What is?"

"What you just said."

"Huh?"

"About the blood sugar. Maybe something keeps their blood sugar permanently low, so they're constantly hungry. We may make a scientist out of you yet."

He didn't look up; he just grunted, "Don't be insulting."

I didn't bother to respond. I was still considering his offhand suggestion. "Two questions. How? And why? What's the purpose? What's the survival advantage?"

"Um," he said, guessing. "It's fuel. For growth?"

"Yeah ... and then that raises another question. How old are these things? And how big are they going to get? And does their appet.i.te keep pace? And what is their full size? Or is this it?" I sat down on the edge of one of the tables, facing the gla.s.s wall of the millipede cage. I began chewing on the end of my pencil. "Too many questions-" Hanging around the millipedes was affecting my eating habits. I folded my arms across my chest. "And what if we're not asking the right questions in the first place? I mean, what if it's something so simple and obvious that we're overlooking it?"

"Hm," said Ted; then, "Maybe they're not getting the right kind of food-and that's why they stay so hungry......"

"Hey!"

Ted looked up. "What?"

I pounced on the thought. "Try this: maybe they're dextro- and we're levo--they're made out of right-handed DNA! And they need right-handed proteins to survive! And this is a left-handed world!"

"Um," said Ted. He scratched his nose and thought about it. "Yes and no. Maybe. I have trouble with the right- and left-handed idea. I don't think it's possible. It's certainly improbable."

"The worms themselves are improbable," I pointed out.

He scratched his nose again. "I think the fact that they can safely eat any Earth-based organic matter without immediately falling down, frothing at the mouth in deadly convulsions, is a pretty good sign that our respective biologies are uncomfortably close. If I didn't know better, I'd say almost related."

Another idea bobbed to the surface. "Well, then-try it this way. Earth isn't their native planet, so maybe they have to eat a lot of different things to get all of their daily requirements. I mean, their metabolisms must be different because they've evolved for a different set of conditions, so they have to be unable to make the best use of Earth-type foods-it follows, doesn't it? -so they'd have to increase their intake just to survive."

"Um, but look, if that were true of the millipedes, then it would have to be true for the worms. They'd have to be even more ravenous than they already are. They'd be eating everything in sight."

"Well, they do, don't they?"

He shrugged. "Who knows what's normal for a worm?"

"Another worm?" I suggested.

"Mm," he said. And then added, "-Except, there are no normal worms on this planet."

"Huh?" I looked at him suddenly.

"It was a joke!" he said.

"No-say it again!"

"There are no normal worms on this planet."

"What did you mean by that?"

He shrugged. "I don't know; it just seemed ... obvious. You know? I mean, we don't know what the worms are like in their own ecology; we only know them in ours-and we don't even know how they got here. So if there's something-anything-that's making them or their behavior atypical, we wouldn't know, would we? And neither would any other worm on this planet, because they'd all be experiencing the same effects."

"That's great!" I said, "It really is-I wonder if anyone else has realized that yet."

"Oh, I'm sure they have-"

"But I'll bet that's part of the answer. We're dealing with crazy Chtorrans! And I like your other idea too-about something keeping their blood sugar permanently low. I just wish I had a good biological justification for it." I scribbled it into my notebook. "But it fits in with something else. Here, look at these-" I went rummaging through the mess on the desk behind me and came up with a folder marked UGH. I pulled out a sheaf of color eight-by-tens and pa.s.sed them across. He stood up to take them. He leaned against the table and began to leaf through them. "When did you take these?"

"This morning, while you were on the terminal. I finally found my close-up lenses. There's some real high-power stuff there. Look at the structure of their mouths."

He grimaced. "They look like worm mouths."

I shrugged. "Similar evolutionary lines, I guess. What else do you see?"

"The teeth are like little knives."

"You notice anything else? The teeth are slanted inward. Here, look--compare these two pictures where he's eating the cigar. When the mouth is at its widest, the teeth are pointing straight up and down and just a little bit outward; but as the mouth closes, they curve inward. Here, see how they mesh? Once a millipede bites something, the teeth not only cut it, they push it down the throat. A millipede can't stop eating-not until the object is finished-because he can't let go. Every time he opens his mouth, he automatically takes another bite; every time he closes, he pushes it down his throat. That's why his teeth have to grind and cut and slash--otherwise, he'd choke to death."

"Um, I doubt that last," he said. "I don't think they're capable of choking. With a mouth arrangement like that, they wouldn't have a swallowing mechanism that could so easily kill them. It would be self-defeating. I'd guess that the arrangement of the teeth is so they can get a good hold on their prey and, if nothing else, get one good bite out of it-like Louis."

"Have it your own way, Perfessor-but I watched him eat the cigar, and that's the way he used those teeth."

"But, Jimbo-that doesn't make sense. What happens to the little b.a.s.t.a.r.d who gets stuck to a tree?"

"He eats or dies," I offered. "Remember what you learned in school: 'Mother Nature doesn't give a s.h.i.t.' "

"Um," Ted said, shaking his head. He continued paging through the photographs. "How did you shoot this one?" He was staring down the wide-open mouth of one of the millipedes.

"Which one? Oh, that. I shot that through a pane of gla.s.s. There's a spot of grease smeared on it; he's trying to bite it off. The focus isn't so good because of the grease, but it was the only way I could look down his mouth. They learned real quick that they couldn't get through the gla.s.s, so they stopped lunging at it when I held up a finger. That's why the grease. Here, this one's sharper-this was before he scratched the gla.s.s."

Ted peered close. "Hand me that magnifying gla.s.s, will you? Here, look-what do you make of this?"

"Hey! I didn't notice that before-a second row of teeth!"

"Mm," said Ted. "I wonder if he ever bites his tongue."

"Those are molars!" I said. "See? They're not as sharp. The first row is for cutting; these are for grinding. And look-do you see anything farther back?"

"Uh, I'm not sure. It's awfully dark down there."

"We can digitize this and bring up the resolution, but doesn't that look like a third row?"

"I can't tell. It could be."

I looked at him. "Ted, maybe these things have teeth all the way down their throats. That's why they can eat so much, and so many different things. By the time the food reaches the stomach, it's been ground to pulp. They'll still need strong stomach acids, but now the food has a lot more surface area exposed to the action of the enzymes."

"Well, this makes them a little more . . . believable." Ted grinned. "I find it very hard to trust any kind of creature that eats tennis shoes, wallpaper and baseb.a.l.l.s, not to mention bicycle seats, clotheslines and Sergeant Kelly's coffee."

"Ted, give me a break. Please."

"All right-they wouldn't drink the coffee. That's probably what the Chtorrans use in that corral fence to keep them from getting out-Sergeant Kelly's coffee grounds."

"Oh, no," I said. "Didn't I tell you?" He looked up. "What?"

"You should have guessed. What's the one thing the millipedes won't eat-the one organic thing?"

He opened his mouth. He closed it.

"That's right," I said. "Used food. No creature can live in its own excrement-those are the things its metabolism can't use. And that's what the worms put between the double walls of their corral. As soon as the millipedes sense it, they back away."

"Wait a minute, boy-are you telling me the worms are going around gathering up millipede droppings for fence insulation?"

"Not at all. I didn't say anything about millipede waste. I just said it was waste"-he opened his mouth to interrupt; I didn't let him-"and it's not terrestrial waste either. Remember we were wondering why we never found any worm droppings? This is why. Evidently, the worms have been using it to keep their 'chickens' from escaping. The worms and the millipedes must be similar enough so that it doesn't make any difference. What a worm can't use, neither can a millipede. The tests on the droppings from the enclosure and the specimens we've got here show a lot of similarities. Mostly the differences are dietary, although a lot of the special enzymes don't match up. If I had more sophisticated equipment, I'd be able to spot the subtler differences."

Abruptly, Ted's expression was thoughtful. "Have you written any of this down?"

"I've made some notes. Why?"

"Because I heard Duke talking to Dr. Obama about you-about us. He wants Obie to send us to Denver."

"Huh?"

Ted repeated it. "Duke wants Obie to send us to Denver. With the specimens. On Thursday."

I shook my head. "That doesn't make sense. Why should Duke do any favors for us?"

Ted perched himself on the edge of the table. The three millipedes looked at him with patient black eyes. I wondered if the mesh of their cage was strong enough. Ted said, "Duke's not doing us any favors. He's doing it for himself. We don't belong up here and he doesn't want to be a babysitter. And after what happened with Shorty-well, you know."

I sat down again. I felt betrayed. "I thought ... I mean . . ." I shut up and tried to remember.

"What?" asked Ted.

I held up a hand. "Wait a minute. I'm trying to remember what Duke said." I shook my head. "Uh uh-he didn't say anything. Not about this. I guess I just thought I heard-" I stopped.

"Heard what?"

"I don't know." I felt frustrated. "I just thought that we were going to be part of the Special Forces Team."

Ted dropped off the table, pulled the other chair around and sat down opposite me. "Jim boy, sometimes you can be awfully dumb. Listen to your Uncle Ted now. Do you know where these Special Forces Teams came from? I thought not. These are-or were-top-secret crack-trained units. So secret even our own intelligence agencies didn't know they existed. They were created after the Moscow Treaties. Yes, illegally-I know-and you used a flamethrower last week, remember? It saved your life. Guess what the Special Forces were for-and a lot of other innocuous looking inst.i.tutions. Too bad you slept through history, Jim, or you'd understand. Anyway, the point is, these men have lived together and trained together for years. And they're all weapons experts. Have you ever seen Sergeant Kelly on the practice range?"

"Huh? No-"

"Well, you should-or maybe you shouldn't. You'd be too terrified to complain about her coffee. These people think and act as a family. Do you know what that makes us? Just a couple of local yokels. We're outsiders-and there's nothing we can do that will change that. Why do you think Duke gave us this labpractically shoved it on us? Because he wants an excuse to send us packing. And this is it. He'll be able to say we're too valuable as scientists to be risked out here in the field."

"Oh," I said. "And I was just beginning to like it here."

"Better than Denver?" Ted asked.

"I've never been to Denver."

"Trust me. You'll love it. It'll be just like civilization. Jim, do you really want to stay here, where the odds are seven to one that you'll end up in a Chtorran stewpot? Or didn't you know that?"

I didn't answer right away. At least now I knew why Ted had been so cooperative these past few days. But I still felt as if a rug had been yanked out from under me. I looked across at Ted. He was peering into my face, still waiting for my reaction.

"d.a.m.n," I said. "I wish you weren't always so ... ubiquitous." He shrugged. "So what? You'll thank me for it in Denver."

"I know. That's the annoying part!"

FIFTEEN.

THE THURSDAY chopper was pushed back till Sat.u.r.day, so we had four days left-if we were going. They still hadn't told us. Ted said that was the army way. If they told us, we'd only worry about it. This way, we didn't have anything to worry about.

I worried anyway-and made the best use I could of the time. I borrowed the helmet camera and set it up in front of the millipede cage. I digitized the image, fed it into one of the computers-and I had an activity monitor. The program counted the number of pixel changes per second, noted the scale of change, the time and the temperature. As it built up information, it correlated trends, fit them into curves and made them available for display on continually updating graphs.

The bugs did not like heat. Temperatures above twenty-five degrees Centigrade made them lethargic, and higher than thirtyfive degrees they refused to move at all. Generally they seemed to prefer a ten-degree environment, although they remained active at temperatures as low as freezing. Lower than that, they would curl up.

I repeated the tests under different lighting conditions. The bath house had been rigged with two bare twelve-hundred-lumen plates; when I replaced them with outdoor lamps, some of the vari-temp, night-into-day lights for hydro- and aeroponics, the millipedes curled up as if to shield themselves, regardless of the temperature. Clearly, they did not like bright light.

But I wanted to measure their activity levels through a full range of lighting conditions, charting the curve all the way from pitch dark to bright sunlight-and through a complete range of temperatures too.

We borrowed the air conditioner from Dr. Obama's office-we didn't dare try to take the one from the mess hall-and Larry found a spare heater for us somewhere. Between the two I was able to achieve most of the test temperatures I wanted. I rewrote the program, put the lights on a rheostat with a photodiode to measure the lumens and connected everything to the computer.

The result was a two-dimensional data-base demonstrating the millipedes' reactions to a variety of environments.

But it was inconclusive. The bugs liked low temperatures and dim lights. They tolerated high temperatures. They didn't like bright lights at any temperature. That didn't make sense. It was too simple. Did they come from a dark planet? There wasn't enough data.