The most critical step in any medical experiment is going from test animals to human trials. Usually this step is taken very carefully. But sometimes . . .

 

WILLIAM WALLING

 

"Greetings, respected colleagues!"

Clancy Bevvins looked up as Lee Gresham, still youthful enough to be flippant about his troubles, swam through the research satel­lite's commissary hatchway with a casual wave for him and Thaddeus Frye, who, though no longer that young, was very intelligent, very lean, very black—and extremely good-natured. An expatriate New Zealander, Bevvins considered his own troubles to be all in the past. He was returning to Earth in ex­actly forty-one days. He was count­ing the days.

"Hullo, Lee," hailed Bevvins. "Off watch so soon?"

"Uh-huh!" Gresham closed the hatch, which battened automatically behind him. He floated to the hand rail, tugged himself into what passed for a sitting position at the bench, and wearily clipped a folder bursting with photo plates and notes in the hold-down fixture on the table.

"Why, good evening, Dr. Gre­sham," said Frye with a twinkle. "How are things out in your lone­some observatory?"

Gresham rubbed his eyes. He dialed for coffee before answering. "Today, I spent six hours staring into that damned blink comparator," he said. "Ever tell you I'm thinking of writing a book? I'll call it The Vicissitudes of an As­trophysicist."

Bevvins and Frye exchanged amused glances. "I say! That's some sensational sizzler of a title," hissed Bevvins. "But, you've never gotten round to explaining what­ever it is you're searching for."

Gresham's lip curled. "That again? You two never tire of bait­ing the new help, do you? You know I can't talk about it."

"More secret government jazz, eh, Lee?" asked Thad Frye dryly.

Gresham sucked his squeeze bottle of coffee, leering at them from pale, bloodshot eyes. He swal­lowed, lifting the tube from his lips. "It won't work; no more put-ons, thank you kindly," he said. "By the way, Dr. Bevvins, what's a nice cellular physiologist like you doing in a place like this?"

Frye's hearty laugh boomed through the small compartment. “When in doubt, attack! You're learning, my boy."

Bevvins chuckled. "Actually, there's nothing secret about my work," he said, hoping that it sounded convincing. The sally had merely been young Gresham's way of congratulating him upon his im­minent return home—his "escape," as the astronomer insisted on put­ting it. "I've been tracking some­thing rather interesting, you see. Did a good bit of the early work sunward, in Phobos Station, then decided to move out away from primary solar radiation as far as was practicable—"

"—And solved the riddle of life," suggested Gresham tiredly, "with old Jupiter's help."

"No, not really. Jupiter's a dis­traction, if anything. Getting stuck here in Zipper One was the commissioner's idea, not mine. It was the only facility this far out with lab space available for me, Hector, Bess, and the others."

"Oh, your chimps."

"Uh, gibbons," corrected Bev­vins. "I've no complaints whatsoever. Don't mistake me, I shall certainly be glad to see Christchurch again. But, it's been quite rewarding."

"Wouldn't Ganymede Base have done as well?" asked Gresham. "It's a lot more comfortable than this tin bar-bell; room to move around, and at least a little weight on your feet."

Bevvins shook his head. "I'm afraid weightlessness is a requisite, Lee. That is, my studies demand . . . no need to bore you with a lot of medical frou-frou." He patted the tabletop. "Zipper's been good to me. I've accomplished more than I'd dreamed possible in my six months with you chaps."

Heavily shielded against the strongest Van Allen radiation belt in the entire solar system, Zipper One—technically Jupiter Research Satellite One—hurtled around the largest of the planets in a high ve­locity orbit just inside the groove of the tiny moon Amalthea, which cir­cled but seventy thousand nautical miles from the banded giant. Trapped in a cross-rough of physi­cal science specialties making up the other nine members of Zipper's research crew, Dr. Bevvins had agreed to "pay his way" by dou­bling as the station's medical offi­cer. He had resented the time sto­len from his own work in relieving sprains, checking urine samples, and rolling pills.

Finishing his coffee, Lee Gre­sham took a black-bowled briar from the slash pocket of his jump­suit. He chewed the dry stem fitfully, a faraway look in his pale blue eyes.

Thad Frye winked at Bevvins. "The old nicotine heeby-jeebies hassling you again, Lee? I thought you'd kicked the habit."

Gresham made a disgruntled sound. "Just one more vicissitude we astrophysicists must face," he said theatrically, stressing the sibi­lants. "I miss my damned pipe more and more every minute. One of these days, I'm going to stoke it and light up—and to hell with regu­lations!"

Frye clucked in mock dis­approval. "In a pure oxygen environment? Naughty, naughty!" He stretched and groped for the over­head hand rail. "Well, I expect it's time to go and relieve Kawashima on watch, gentlemen. Better keep an eye on our junior colleague, Clancy. Those vicissitudes may gang up on him and get completely out of hand."

His broad, negroid features crinkled pleasantly, the gangling older man made one long-armed heave on the freefall line as Gre­sham sheepishly stuffed his pipe back in his pocket. Smiling, Bevvins simply nodded his good-bye.

Dr. Thaddeus Frye, whose spe­cialty was cryogenic physics, was just reaching out to pop open the hatch, when the sound hit them—a high-pitched grinding noise, fol­lowed almost immediately by the squalling howl of the pressure warning klaxon.

Bevvins, his heart in his throat, lifted his feet to shove away from the table. Mild acceleration nearly sent him flying. He grabbed for the bench, and saw Thad Frye tumble past end-over-end to crash against the galley bulkhead and slide limp­ly back toward the deck.

Gresham clung to the table op­posite Bevvins, yelling, "We've been hulled!" He shouted it, in­anely, over and over again.

Slowly, the acceleration dwin­dled. They were weightless once more. Bevvins found himself trem­bling. He stared blankly at Gresham for an instant before he pushed free of the bench. "Come, let's see to Thad."

Frye groaned and stirred as Dr. Bevvins clasped his wrist. He peeled up one of the physicist's eyelids, while Gresham hovered anxiously close by. At last, Frye opened the other eye, gingerly rub­bing his temple. "Some ride, that was! What happened?"

"We've no idea, just yet," Bev­vins said. "You look to be all right. How do you feel?"

Dr. Frye fingered his thinning, kinky hair. "Short of a knob on the skull, and a sore shoulder, I guess I'm in one piece, but . . ." He paused, his nostrils flaring. "Clancy, if what I hear—or don't hear—isn't my imagination, we're in a peck of trouble."

"What is it?" asked Bevvins.

"The blowers are off," said Frye. "At least, I don't hear them. Our life support system must be out. Listen!"

The warning klaxon had stopped howling. Bevvins and Gresham strained with every sense into the stillness.

Zipper One's commissary com­partment was quiet as the tomb it might very soon become.

'Gresham punched one intercom switchlight after another. "Hello, A deck; anybody in A deck?" He re­peated the call for B, C, and D decks, then tried to reach the ser­vice compartment two levels be­neath them, as well as the power reactor module which occupied the far section of the dumbbell-shaped structure Zipper One resembled. The response from every intercom station was the same—chilling si­lence.

"No one's out in the observa­tory," said Gresham, frowning. "I know; I just came in from there." There was a good deal of fright in his expression.

"Clancy, how much air's in here?" asked Frye, clenching and unclenching his fists.

"Uh, something like three or four hours of usable air, I'd guess," said Bevvins. "But we've got to find out what the situation is straight off. Have we a survival kit?"

"There's one in every com­partment," said Frye, "but . . ."

"I know what you're thinking, Thad." Bevvins was grim. "You are speculating upon whether there is still air beyond the hatch."

Gresham looked from one to the other. He pulled out his pipe for comfort, his brow wrinkled. "Hard to say, but we'll have to keep hop­ing. We might be able to save the others if we move fast. Everyone agree?"

Frye clapped his hands. "Done!" He shoved away to get the emer­gency kit. A huge, red dayglo ar­row pointed to the survival locker in the pantry, just off the galley. The emergency p-suit Frye broke out was fashioned of light-weight, sealant-impregnated mesh, topped with an ovoid fishbowl. The chest-slung oxygen bottle would sustain a man in vacuum for only about twenty minutes.

"We'll draw straws," suggested Gresham.

"Put away your pipe, Lee," or­dered Bevvins. "We shall have to count on you; you're the youngest and strongest. We'll assume the re­mainder of C deck is intact."

"Come on, Lee," urged Frye, "snap it up!"

With expertise gained in long practice, Gresham wriggled into the p-suit in mid-air, while Frye hung behind him and checked out the flow valve. Before clamping down the fishbowl, Gresham said, "First, I'll look through living quarters, then work my way up to A deck and get a mayday tape ready to put on the lasercomm transmitter." He squinted at the wall chronome­ter which read in universal time. "Ganymede should be nearing op­position; it will be several hours before we can fire off a signal, but it's best to be ready. Sound O.K.?"

"Find out as much as you can," said Bevvins. "Check on my animals, too, if you get near the lab."

"Will do." Gresham hurriedly sealed up. He flew to the hatch.

Thad Frye made a thumb and forefinger doughnut of encouragement, muttering, "Go on, son; don't keep us in suspense."

The two older men held their breath, knowing the hatch would refuse to open if the passageway beyond held no air, dooming them to hours of slow suffocation. Bev­vins wasn't at all sure he could stand that.

Lee Gresham stabbed the button. The hatch opened normally. He disappeared, and the hatch bat­tened behind him.

"Whew! I'm getting too old and paunchy for this sort of drill," said Bevvins. "Did it sound like a punc­ture, do you think? Pressure loss doesn't scare me half so much as that acceleration. What the devil could have caused it, Thad?"

Frye refused to guess. "Lee will find out. What say we have a look outside? It may give us a clue." He tugged open the dogs securing the radiation-proof cover of a two-foot diameter peek-a-boo, and swung the cover back against the bulk­head.

Zipper One was tumbling very, very slowly in a clockwise direction. The looming, crescent bulge of Jupiter shouldered up to fill the glass, a kaleidoscope of turbulated belts ranging from bluish-white to pastel yellow, and down the color scale to rich saffron and ochre. The red spot broke the south tropical current flow like a glowing, red­dish-gray wound, bounded by a vortex swirl of frozen atmospheric ammonia crystals.

Most bodies, when seen from space, appeared suspended as in a diorama—"out" rather than "down." To Bevvins and Frye, there was no doubt at all; they were looking down into a gravity well more than two and one half times deeper than that of Earth. Near the darkened limb, a single bright dot swam against blackness—probably Io—while the shadow of Callisto crawled in transit near the terminator. Thousands of miles be­low the shadow, gravity had crushed Jupiter's core into a solid mass of compacted hydrogen atoms.

"Zipper's picked up some angu­lar momentum," mused Dr. Frye, rubbing his jaw. "Attitude com­puter must be out, too, or we'd have corrected by now. Doesn't look promising, does it, Clancy?"

Bevvins mumbled something ap­propriately incoherent. He found himself thinking of the sheep sta­tion in Mackenzie Basin where he had lived as a boy: lacy white clouds scudding in an azure sky, with Mount Cook and the South­ern Alps serrating the horizon. But New Zealand lay forty-seven light-minutes sunward. Bevvins had a sudden, sharp premonition that he would never see South Island again.

They waited, nerves jangling—though both tried hard not to show it—until the opening hatch grated behind them. Lee Gresham un­snapped the dogs of his fishbowl. He tilted it back, his features jelled in dismay; above high cheekbones, his eyes were hollow.

"Bad?" asked Frye bluntly.

Gresham's nod was profound. "Bad! A good-sized chunk of debris took us dead-on—probably a piece of sky-junk from the Trojans. Four were asleep in their bunks when B deck depressurized. They aren't . . . pretty to look at.

"Kawashima and Bispham were stowing electronics spares in the service compartment. They didn't have a chance. Burke was up in A deck. He did manage to break out a suit—almost got into it—but . . ."

"Ruddy awful!" Bevvins folded his arms, blinking back tears. "Then, we're all . . . that's left. How about the oxygen reservoirs?"

"It couldn't have been worse," said Gresham dully. "Draw a line through the main pressure vessel down in service, up through all decks to the backup supply in A deck, and you'll have the projectile's path. It took the lower tank squarely, rupturing both hemi­spheres, then struck the upper res­ervoir tangentially and ripped a foot-long gash. The erupting lox was what gave us that acceleration nudge, as well as some spin."

"Good Lord!"

Thad Frye had listened closely. "Perhaps it did something else, too," he said. "If I've followed your description, that gash in the A deck tank opens on the spaceward side, away from Jupiter."

"I . . . know." Gresham was per­spiring. "I would have to run some numbers through the machine to be certain, but it looks like the thrust may have disturbed our orbit. Zip­per might eventually decay and go in, if the guidance computer and thrusters are out.

"But, that's not our main worry. There doesn't seem to be enough oxygen left aboard to keep one man alive till we're relieved, let alone three!"

Gresham went back up to A deck to critically align the lasercomm transmitter and set the timer. Even considering their com­bined orbital vectors, Ganymede would not rise into Zipper's line-of-­sight for another two-plus hours. When the huge moon did appear, not only the radiation belt in which Zipper orbited would act to make ordinary radio communication to­tally useless; like an unlighted mini-star, mighty Jupiter emitted much more energy than it received from the distant sun, including a chaotic jumble of radio frequencies that blanketed all wavebands with crackling intensity. Only modulated light communication was possible between Zipper One and Jupiter's natural satellite.

While Gresham was gone, Bev­vins and Frye took inventory. Three quadrants of C deck, in­cluding the" commissary, had been reported intact by Gresham, al­though there was no practical way to scavenge the remaining free air and bottle it. Zipper One, equipped for a personnel complement of ten, was just below the efficiency break-even point necessary to carry oxy­gen regeneration equipment on board. Liquid Oxygen, stored in primary and backup pressure ves­sels installed poles apart in the crew module to lessen the chance of both being ruptured by a single meteoroid, was replenished period­ically by logistic resupply shuttles from Ganymede. Unfortunately, the large EVA bottles needed for spaceside activity were charged from reduction tanks plumbed to the main storage vessels, rather than being held permanently charged in the air lock service area.

"Hell's fire! This deck of cards is really stacked against us!" Thad Frye looked very glum. "There might be a partial charge in a scat­tered bottle or two, but . . .Clancy, you all right?"

"Eh? Yes, of course, Thad. I was thinking of something else. Never mind; it's too ridiculous to ... You are perfectly correct; it requires nearly two mass-pounds of oxygen per man, per day, to stay alive.

"Barring the air remaining in C deck, and perhaps several compartments in other decks, what we have left could be measured in ounces."

Thad Frye's lips pursed in a si­lent whistle. "That's it, then. Even if there were only one of us . . . I don't see a way home, Clancy. Do you?"

But Dr. Bevvins had taken to staring absently down at Jupiter. He seemed to have withdrawn within himself, deep in thought. Frye respected his privacy, but watched him with an anxious, burning intensity that Bevvins would have found unnerving had he thought to look around.

When Gresham returned, dejec­ted and gloomy, Thad Frye broke in on Bevvins' seeming reverie. "How much time's left, Clancy?" he asked quietly. "I'd like to write some letters."

"What?" Bevvins looked startled. "What was that?"

"How long . . . before—"

"No, no!" Bevvins realized that he was shouting. He lowered his tone. "No, let's not strike ourselves off until we've exhausted every pos­sibility," he said earnestly.

"But—"

"Lee, how soon can we expect relief from Ganymede? After they receive our distress signal, of course."

Gresham had been forlornly shucking off the emergency p-suit. He paused. "I'd say forty to fifty hours, if Ganymede's on their toes, and everything goes smoothly."

"I . . . see. Do we, er, have that much time? Before crashing down into Jupiter's atmosphere, I mean."

“Oh, hell yes! The mild nudge that lox rupture imparted won't af­fect Zipper's orbit for hundreds of hours. I didn't take time to make any doppler readings, but—"

"What blessed difference does it make?" demanded Frye, as close to anger as either Bevvins or Gresham had ever seen him. "We have to breathe until they grab us!"

"Er, yes; I hadn't intended to broach the subject just yet, but ... perhaps we do have something to breathe."

Gresham looked puzzled. "What the hell do you mean?"

"Precisely what I said," an­nounced Bevvins cryptically. "By the way, did you manage to look in on my animals, Lee?"

The astronomer groaned. "Yeah, they're O.K., doc. It's one helluva time to be worrying about monkeys, though!"

"It may be very important," said Bevvins. "Very important. If Bess is still alive and well, we may have a chance. It's a slim chance, and will seem absolutely far-fetched to you. But, any chance is better than none."

"We sure won't argue that point," said Frye, tight-lipped. "Get it off your chest, Clancy."

Bevvins cogitated. He took a deep breath; the air in the compartment was still untainted. "Thad, you and I were ribbing Lee, earlier, about his secret government project. I've a confession to make: I have been working on a similar assignment, under similar restric­tions, for almost six years.

"Lee was also quite correct in guessing that Ganymede Base—or Luna, or Earth, for that matter—would have been a much more proper site for biomedical research than Zipper One. You see, neither solar radiation levels nor zero-gee have anything whatsoever to do with my work."

Bevvins hesitated. "The real rea­son our security chaps insisted that I barge in here with my gibbons was for the utter isolation it afforded. Here, in Zipper One, I've been surrounded by gentlemen like yourselves—physical scientists of one discipline or another. There is not one biomedic, nurse, or medi­cal researcher nearer than Gan­ymede Base."

Frye opened his lips as if he wanted to say something, then decided against it. Lee Gresham arched his brows uncertainly. "Go on, doc."

"If—I repeat if—another medic had had occasion to look in on my laboratory, he would have noticed something damned peculiar," said Bevvins. "Hector—he's the duff-col­ored fellow in the leftmost wire cage, Lee—lives as we do in the air supplied by our now defunct life-support system, while Bess, the black and tan girl, is in the bubble cage under glass. If you'll think about it, you may remember that no air ducts run to that bubble."

"No, I . . ." Gresham shrugged. "Do you mean the monkey with all the wires attached to it?"

"That's her. For three months, Bess has lived and prospered while sealed off from the ambient air of the lab, surrounded by nothing less than the carbon dioxide product of her own metabolism. I've broken the seal only to water and feed her, and to clean her cage." Bevvins waited while the others digested what he had said.

Gresham frowned. "I don't get it."

Frye coughed politely into his cupped hand. "It sounds impossible, Clancy. There must be hair growing in it someplace, or you'd be prepping us for surgery, or whatever, right now. Carbon diox­ide, huh? How do you do it—an enzyme?"

"I say! That's an excellent guess, Thad," congratulated Bevvins. "If they were here, the security people would fret about you. I discovered Bevvinase—classified documents re­fer to it as Bevvinase, so perhaps the name will stick—while doing some work on oxidation, er, the manner in which cells use oxygen.

Actually, the theory had been pro­posed in any number of earlier pa­pers: an enzyme which would con­vert carbon dioxide to oxygen en vivo, as do plants. Someday, we hope to eliminate thoracic breath­ing entirely, effecting at least par­tial human adaptation to the spatial environment. But, for our present dilemma, trying to emulate Bess is our best and, it would seem, only hope."

"Trying . . . to emulate Bess," faltered Gresham.

"I'm afraid so. The 'hair' Thad mentioned does exist. You yourself noticed the way Bess is wired, Lee. She's monitored constantly for phrenic nerve activity, hemoglobin oxygen and carbon dioxide content, turnover rate, oxygen diffusion rate, and a number of other vital func­tions."

Gresham was earnest. "What does 'turnover rate' mean?"

"The enzyme's regeneration rate in the tissues," explained Bevvins. "Bevvinase becomes self-perpetu­ating when the coenzyme, which I've labeled . . . Oh, we've no time to get bogged down in a morass of medical detail. In simplest terms, enzymes are a form of pure protein substance which cannot be synthe­sized. Hector is my Bevvinase fac­tory; Bess my subject—my 'patient', if you will."

Frye smiled for the first time since the accident. "Get to the hair, Clancy. What's the problem? It will get stuffy in here by-and-by."

Bevvins cleared his throat. "There are two enormous tufts of hair," he said. "One: while won­derfully useful as analogs, gibbon monkeys are most definitely not human beings. God, there are so many, many unknowns! I shan't be able to devise any sort of control at all, and I shall have to guess at dosages for each of us. And, if I'm wrong . . ."

"Guess good, Clancy. What's the other?"

"Homeostatic control mecha­nisms in the body," Bevvins said. "There are interesting push-pull phenomena called the Bohr and Haldane effects: carbon dioxide and oxygen work together because of some unique and fascinating properties of hemoglobin. Adding carbon dioxide to the blood tends to drive out oxygen, helping deliver it to the tissues, whereas adding ox­ygen helps drive out carbon diox­ide through respiration. There are specialized nerve cells called chemo­receptors which constantly readout blood composition to the central nervous system, chemically con­trolling breathing. Bess has surgi­cally implanted instrumentation which allows me to make certain adjustments. With ourselves, how­ever, it will be hit . . . or miss."

"Whoo-o-o-ie!" Gresham waxed his hands. "We're home free!"

"Please, Lee," said Bevvins wor­riedly, "I've tried not to paint too rosy a picture. I've oversimplified everything awfully. We are far from being out of the woods, be­lieve me."

Gresham stared at the physi­ologist. "You mean, you're not sure it will work?"

"Uh, not at all certain, no. Not with us."

Thad Frye beamed. "Why are you quibbling, Lee? If the odds were ten million to one, we'd still have to chance it."

"Are the odds that high?" Gre­sham wanted to know.

"Oh, by no means! I should say the odds are no more than two to one. Eight to five would probably he closer."

Gresham hesitated. "For, or . . . against?"

Bevvins sighed. "If I were less than honest, Lee, I would tell you the odds favored us. They do not."

No one said anything for a dozen heartbeats. Bevvins pondered Jupiter, avoiding their eyes.

Then Gresham laughed. It was a brittle laugh, tinged with hysteria. "What the hell are we waiting for? Lead us to it, doc; I can't wait to find out if your crazy jungle juice works!"

Bevvins ordered Gresham to bring three EVA-rated pressure suits up from the air lock service area, explaining that they would later need them to insure re-in­spiring concentrated carbon diox­ide. Bevvins went along with Gre­sham as far as his laboratory in the C deck quadrant opposite the com­missary. He unlocked the refrigerator and withdrew a small vial of colorless fluid. He wrapped it se­curely in linen batting and zippered it into the slash pocket of his jump­suit, then floated for a moment near the animal cages, watching the chat­tering gibbons.

Hector and his friends in the wire cages loved weightlessness. Each had a distinctive personality, and Bevvins had learned to know them well—Polly's grumpiness, Robin's avarice, Portia's agile grace in flying to and fro in the larger cage.

"Can't have you suffering, can we?" he muttered sadly. "Not enough to go round, I'm afraid." He selected a syringe and filled it, his hands trembling ever so slightly. Soothing them one by one, he did what had to be done quickly and efficiently. There were tears in his eyes when he finished.

He went to the acrylic bubble, in which a black and tan gibbon re­posed. "You'll do, Bess," he mum­bled, reading the bioinstrumenta­tion displays of a tan electronic console. "Sleep, girl; we'll have you out of here in a jiffy. If we are very, very lucky," he added thoughtfully.

Bevvins stopped by the infirmary and got out a sterile syringe boxed in a plastic tube. He put it in his bag, selected three tips, then pulled himself along the freefall line to the elevator. He met Gresham and Frye in the living quarters.

"First, a sedative," Bevvins said. "We will want to remain absolutely immobile. Excitement, or even mild exertion, could induce hypernea­rapid breathing. My scheme is to inoculate you both, then monitor your progress as best I can until it's time to close your fishbowls."

Gresham swallowed noisily. "Can't say I like the sound of it much," he said.

Thad Frye grinned. "Just one more astrophysical vicissitude, Lee. It's like growing old. Being my age isn't so bad, when you consider the alternative."

Neither Bevvins nor Gresham cracked a smile. Bevvins administered sedative to each, then checked blood pressures, pulse rates, and oral temperatures. He asked for their respective mass-weights and ages in both years and months.

When all was ready, all three men donned the cumbersome, radiation-shielded p-suits. Thad Frye allowed Bevvins to loosely affix the restraint straps binding him to his bunk. "Sock it to me, Clancy," he said cheerfully.

Bevvins performed some calcu­lations on a note pad, then pre­pared a syringe, and administered Bevvinase at Frye's wrist.

Gresham watched, round-eyed and apprehensive, as Thad Frye's chest heaved normally for three or four minutes. Then the physicist lapsed into very shallow breathing.

"First surge of Bevvinase." Bev­vins grunted something else under his breath. He did some additional calculations. "Bess was comatose for the first dozen hours, or so, Lee. Please don't fret about Thad's breathing. He seems to be taking hold rather well."

"You're . . . sure?"

Bevvins tried to make his smile reassuring. "I'm sure. We won't close his fishbowl just yet."

"Are you . . . ready for me, now?"

"Yes, Lee. On the bunk, if you will."

Bevvins watched the astronomer closely. Gresham was very nervous, but the sedative was beginning to take effect. "There is no particular hurry," he said. "We can talk for a while, if you'd like."

Gresham's half-smile was drowsy. "Naw, doc. Like Thad said: sock it to me."

Bevvins attended to Gresham gently. He shoved himself away and took up the note pad, writing furiously for many minutes. He looked up at the chronometer now and again, checking their respira­tion rates. Finally, he decided it was time. He examined Frye ex­haustively, then pulled down and sealed his fishbowl. When he had finished writing, he drifted over and did the same for Gresham.

The moment of truth had come. Bevvins had not taken sedative for a very good reason. He would have to stay conscious long enough to close his own fishbowl at the ap­propriate time. Timing was very-critical; if he sealed himself off from the remaining air in the living quarters too soon, he would die of hypoxia before the Bevvinase could take hold. He had not seen fit to explain this to the others.

Clancy Bevvins readied himself in the bunk. Smiling secretly, he crossed his fingers, daubed his wrist with alcohol, and injected himself.

"He's coming around," someone said far away. "Look!"

Dr. Bevvins opened his eyes. He blinked several times, lifting his head. Lee Gresham was grinning at him from a hospital bed across the small compartment. Beside him, enjoying himself hugely, stood the lanky figure of Thaddeus Frye.

"Well, how you keeping, Clancy?" The black physicist walked to his bedside with a springy step, clasping his hand. "You did it! You said you could do it and, by God, you did it!"

Bevvins smiled thinly, still fully occupied by the process of reviving. "We seem to have made it, at that," he said.

"And how!" Gresham bounced on the bed. "Weight! Feel it? Now that you're awake, doc, see if you can help bust us out of quarantine. They come in here and feed us and look us over dressed in pressure suit-like coveralls—fishbowls and all. You'd think we were con­tagious."

Bevvins used his arms to slowly erect himself into a sitting position. Thad Frye fluffed the pillow be­hind him. "I'm damned glad they read my instructions," Bevvins said. "If they hadn't—"

"Instructions!" Gresham swore. "We're on Ganymede," he insisted. "I want my clothes. I'm going for a romp down the midway, and maybe chase a stewardess or two. Most of all," Gresham said fer­vently, "I want my pipe."

Bevvins coughed politely. "Lee," he said, "there is simply no way of breaking it to you gently. The stew­ardesses will have to wait, I'm afraid. As for the pipe, it wouldn't be of any use to you, now."

"What? What do you mean?"

Bevvins considered his answer carefully. "In Zipper One, I had only one patient—Bess," he said. "Now I have four: Bess, Thad, you . . . and myself. Remember what I told you back there in Zipper's commissary: the enzyme is self-re­generating. All of us have become true spacemen. At least, for the time being."

Thad Frye met Bevvins' in­quiring look. "Yeah, I guessed it, Clancy," he said. "I thought maybe it would be a good idea if you told him yourself."

"You mean …!" Gresham's jaw dropped. He studied them with an agonized expression, looking as if he were about to cry.

"What a lousy, rotten way to quit smoking!" was all he said.