Conway disregarded the sarcasm and looked around the ward. While he had been examining the casualty with Naydrad, Murchison and Dodds had stripped the others and were obviously waiting for instructions. Prilicla was already carrying out the instructions that Conway had yet to utter on the first two casualties, but then, Prilicla invariably said and did the right thing because it was an exceptionally fine doctor as well as an empath.

            "If it wasn’t for the very high temperature and general severity of their symptoms," Conway said finally, "I’d say we are dealing with a respiratory infection with associated nausea caused, perhaps, by swallowing infected mucus. But the sudden and incapacitating onset of the symptoms makes me doubtful of that diagnosis.

            "But that is not the reason I stayed sealed," he went on. "There was no reason for doing so at first. Now, however, I think it would be a good idea if Lieutenant Dodds and you sealed up. It may be an unnecessary precaution."

            "Or it may already be too late," said Murchison, unclipping one of the lightweight helmets, which, with its connecting hose, air tank and body webbing, converted the coveralls she was wearing into a protective suit, proof against anything but the most corrosive atmospheres. Dodds had already sealed his visor with remarkable haste.

            "Until we can get them to the hospital," Conway said, "treatment must be supportive rather than curative. Replace the lost fluids intravenously, control the nausea and try to keep the temperature down. We may have to use body restraints to keep them from dislodging their monitor leads. Isolate them in pressure tents and raise the oxygen level. I think their condition is going to worsen, and we may eventually need to assist their breathing with a ventilator."

            He paused for a moment, and when he looked at Murchison he knew that the concern on his face was concealed by the blurring effect of his visor and by the suit’s external speaker, which distorted his voice.

            "The isolation may be unnecessary," he said. "These symptoms could just as easily be due to inhaling and swallowing an as yet unidentified toxin. We can’t be sure, and we haven’t the proper facilities to find the answer in the limited time available. As soon as we find out what happened to the missing crew-man, we’ll whisk them all back to Sector General and submit ourselves to a thorough-"

            "While we are waiting," Murchison broke in, her voice and features now also distorted by a helmet, "I would like to try to discover what it was that hit them, and what it is that may hit everyone else but yourself."

            "There may not be time for that," Conway began, but the voice of the engineer officer reporting to the Captain made him break off.

            "Captain, Chen here. I’ve found the duty roster, sir, and I’ve checked it against the IDs of the casualties. The missing man turns out to be Surgeon-Lieutenant Sutherland, so the Doctor’s guess was right. But his body is not here. I’ve searched thoroughly and he’s not inside the wreck. There are things missing as well-the ship’s portable sound and vision recorders, the crew’s personal recorders, cameras, baggage containers, all missing. Clothing and personal effects are drifting about inside the crew’s quarters as ~f they’d been scattered during a hurried unpacking.

            "Practically all the spare air tanks have gone, and the equipment register shows that the crew’s spacesuits were all logged out for a period of between two and three days, except for the Surgeon-Lieutenant’s suit, which wasn’t logged out and is missing. The ship’s portable airlock is missing also.

            "The Control area is badly damaged, so I can’t be absolutely sure, but it looks as if they were trying to set up for an automatic Jump, and the instrument settings in the Power Room, which wasn’t damaged, supports this. I’d say they were trying to move away from the derelict because of the distortion such a large mass of metal would zntroduce into the Jump calculations, but they collided with it instead."

            "I have the samples for Pathologist Murchison. Shall I come back now, sir?"

            "Right away," the Captain ordered.

            While Lieutenant Chen and the Captain had been talking, Conway had been trying to make sense out of the strange behavior of the Tenelphi’s medical officer. Surgeon-Lieutenant Sutherland had displayed professional competence of a very high order in his treatment of the casualties. Through no fault of his own, he had not been able to communicate properly via the subspace radio although he had made a good try, but he had managed to perform the tricky job of manually releasing and activating the distress beacon. It seemed to Conway that Sutherland was a sensible and resourceful officer of the kind who did not panic easily. Neither was he the kind who would get himself killed accidentally or go without leaving some sort of message.

            "If he isn’t adrift and he isn’t on the Tenelphi," said Conway suddenly, "there is only one other place he can be. Can you land me on the derelict, Captain?"

            Knowing Fletcher’s concern for his ship, Conway expected anything from a flat negative to a verbal explosion at the very suggestion. Instead, he received the kind of response an instructor gives to a pupil of mediocre intelligence-a lecture couched in such elementary language that if the Captain had not been five levels forward in Control, Conway would have risked unsealing his visor to spit in Fletcher’s eye.

            "I can conceive of no reason, Doctor, why the missing officer should leave the Tenelphi when the obvious course would be to stay with the other casualties and await rescue," the Captain began. Then he went on to remind Conway that they did not have a lot of time to waste. Not only should the casualties be hospitalized quickly, but the derelict, the Tenelphi and their own vessel were closing with the system’s sun at an accelerating rate, which would make it uncomfortably warm for all concerned in two days and would cause their hull to melt in four. There was also the fact that the closer they approached the sun, the more difficult it would be for them to make a Jump.

            An added complication was that the Tenelphi and the Rhabwar were now docked and coupled fore and aft so that the ambulance ship could expand its hyperspace envelope to enclose the wreck, which would have to be taken back with them as evidence in the forthcoming investigation into the collision. With the two ships locked together and only one capable of exerting controlled thrust, delicate maneuvering of the order needed to land him on the derelict would be impossible. If Fletcher attempted it, the Rhabwar might well end up in the same condition as the Tenelphi. And then there was the sheer size of the derelict .

            "The vessel is, or was originally, spherical," the Captain went on, and the image from the Rhabwar’s telescope appeared on the Casualty Deck’s repeater screen. "It is four hundred meters in diameter, with residual power and pressure in a few compartments deep inside the ship. But the Tenelphi has already reported the absence of life on board-"

            "Sutherland may be on board now, Captain."

            Fletcher’s sigh made rustling noises on the intercom; then he went on in his patient, lecturing and infuriating voice. "The other ship’s findings are more dependable than ours, Doctor. A life indication is the result of a large number of sensor readings comprising the type and distribution of power sources, vibration associated with the mechanical aspects of life-support systems, pressure and temperature variations within the hull, detection of communication or lighting systems, and many more subtle indications. We both realize that many e-ts require ultra-low temperatures or do not see on our visual frequencies, but if anything, they are easier to detect as far as their life-support requirements are concerned.

            "But right now," the Captain continued, "I could not say with certainty whether or not anyone or anything was alive inside that thing. The close approach to the sun has heated up the outer hull to such an extent that it is no longer possible to detect subtle differences of temperature inside, and the other sensor readings are badly distorted because of the effect of the heat expansion on the structure as a whole. Besides, that ship is big. Its hull is so torn and punctured by meteorite collisions that Sutherland could have found a way in anywhere. Where would you start looking for him, Doctor?"

            "If he’s there," said Conway, "he’ll let us know where to look."

            The Captain remained silent for a moment, and Conway, despite his irritation with Fletcher’s manner towards him, could sympathize with the other’s dilemma. No more than Conway did the Captain want to leave the area without finding or otherwise establishing the fate of the missing Surgeon-Lieutenant. But there was the welfare of the other casualties to consider, which properly was Conway’s responsibility, and the safety of the ambulance ship, which was very definitely Fletcher’s.

            With all three vessels sliding down the gravity well of the system’s sun with an acceleration that did not bear thinking about, the time allocated for a search for the missing officer would be strictly limited, and the Captain would not want to be placed in the position of having to abandon Senior Physician Conway of Sector General as well as the Monitor Corps medic on the derelict. Neither could he risk sending one of his officers with Conway because if he, too, was lost the Captain would have a very serious problem. The Rhabwar’s crew was small and there was no overlapping of specialties. Fletcher would probably be able to Jump back to Sector General eventually, but serious risks and delays would be involved that could adversely affect the casualties.

            The wall speaker rustled with another sigh, and Fletcher said, "Very well, Doctor, you may search for the Surgeon-Lieutenant. Dodds, take the scope. You are searching for evidence of a recent entry into the derelict. Lieutenant Chen, forget the pathologist’s samples for the time being and return to the Power Room. I want maneuvering thrust in five minutes. Doctor, I shall circle the derelict longitudinally at a distance of half a mile. Since it is rotating once every fifty-two minutes, this will enable us to scan its hull surface in four orbits. Haslam, do what you can with the sensors, and give the doctor some idea of the geography of the interior.~~

            "Thank you," said Conway.

            Dodds had been helping Murchison move one of the casualties into a pressure tent. As soon as he was finished he excused himself and headed for Control. Conway looked at the repeater screen and the image of the derelict, half of which was a featureless blackness and half a confusion of brilliantly reflective hull plating that was crisscrossed by black fissures and craters. He glanced at it from time to time while he was helping attach bio-sensors to the casualties, seeing it grow larger and begin to unroll from top to bottom of the screen. Suddenly the image flicked off, to be replaced by a diagrammatic representation of the derelict.

            It showed the cross section of the spherical vessel, with its deck levels making concentric circles to its core. Near the center several compartments of different sizes were marked in various shades of green, and close to the inner wall of the hull at one point there was a large, rectangular compartment marked in red. Fine red lines joined this area with the green compartments at the center.

            "Doctor, Haslam here. I’m projecting a sensor diagram of the derelict’s interior. It is not detailed, I’m afraid, and a lot of it is guesswork..

            The derelict had been a generation transport, Haslam went on to explain, of the spherical configuration favored at a time when maximum living and cultivating space was a necessity. Direction of travel was along the vertical axis, with the control area forward and the reactor and drive units, which were marked in red, astern. The vessel could rotate fairly rapidly around the vertical axis so as to furnish the outer deck levels amidships with artificial gravity even when the ship was using thrust.

            Haslam did not know whether it was one catastrophe or a number of them that had overtaken the ship, but whatever it was it had devastated the control area along with the rest of the outer hull and deck levels and in the process had checked the spin to a fraction of what it should have been. Heavy shielding around the reactors had protected them from serious damage.

            The ship had virtually been depopulated, but a number of compartments deep inside the vessel had retained pressure and power, and a number of survivors must have been able to live in them for a time. These were the sections marked in green. The atmosphere inside some of these compartments was little more than a soft vacuum, Haslam added, but in others it was probably still breathable by the present-day members of the species who had built the ship, whoever and whatever they were.

            "Is there any possibility...

            "No survivors, Doctor," Haslam stated firmly. "The Tenelphi reported the ship lifeless, derelict. The catastrophe probably happened centuries ago, and the survivors survived for only a short time."

            "Yes, of course," said Conway. Then why would Sutherland go there?

            "Captain. Dodds. I think I’ve found something, sir. Just coming into sunlight now. There it is on full magnification."

            The repeater screen showed a small area of the derelict’s ravaged outer hull. There was a black, jagged-edged opening leading into the depths of the ship, and beside it a section of buckled plating on which there was a large, brownish yellow smear.

            "It looks like grease, sir," said Dodds.

            "I agree," said the Captain, then impatiently: "But why would he use grease instead of fluorescent green marker paint?"

            "Perhaps the stuff was handy, sir."

            Fletcher ignored Dodds’ reply-it had been a rhetorical question anyway. ‘Chen, we shall be closing with the derelict to one hundred meters. Haslam, stand by the pressors in case I miscalculate and blunder into that thing. Doctor, under the circumstances I’m afraid I cannot spare an officer to go with you, but a hundred meter flight should pose no serious problems. Just don’t spend too much time in there."

            "I understand," said Conway.

            "Very well, Doctor. Be ready to go in fifteen minutes. Take extra air tanks, water and whatever medical supplies you consider necessary. I hope you find him. Good luck."

            "Thank you," said Conway. He wondered what type of medication would be needed for a doctor who seemed to be physically fit but mentally deranged enough to go exploring in the derelict. Regarding his own requirements, he was less hesitant-he would simply increase the duration of his suit to forty-eight hours, at the end of which time the Rhabwar would depart, whether he found Sutherland or not.

            While Conway was checking the extra tanks, Prilicla flew over and landed on the wall beside him. As they clung to the white plastic surface, the little empath’s legs trembled as if it was being subjected to intense emotional radiation. When it spoke Conway was surprised to discover that the emotion was self-generated. It was frightened.

            "If I might offer a suggestion, friend Conway," said Prilicla, "the job of finding the being Sutherland would be accomplished much more simply and quickly if I were to accompany you.

            Conway thought of the tangle of metal plating and structural members that lay beneath the hull of the derelict, of the danger of rupturing their spacesuits practically every foot of the way, and of the other dangers they could not even guess at. He wondered what had become of the celebrated Cinrusskin cowardice, which in that incredibly fragile species was its most important survival characteristic.

            "You would come with me?" Conway asked incredulously. "You are offering to come with me?"

            Prilicla responded timidly. "Your emotional radiation is somewhat confused, friend Conway, but on the whole flattering to myself. Yes, I shall go with you and use my empathic faculty to help find Sutherland, if he is still alive. However, you already know that I am not a brave person, and I reserve the right to withdraw from the search should the element of risk pass beyond what I consider acceptable limits."

            "I’m relieved," said Conway. "For a moment there I was worried about your sanity."

            "I know," said Prilicla, beginning to add items to its own spacesuit.

            They exited by the small personnel lock forward, the main one being connected to the Tenelphi, and had to listen to Captain Fletcher worrying out loud about the situation for several interminable minutes. Then they were outside, and the hull of the derelict was spread out ahead and all around them like a gigantic wall, so pitted and torn and ruptured by centuries of meteorite collisions that at close range the spherical shape of the enormous vessel was not apparent. As they guided themselves towards it, there was a sudden dizzying change of perspective. The derelict was no longer a vertical wall but a vast, metallic landscape on which they were about to touch down, and the two coupled ships were hanging in the sky above it.

            Conway found it much easier to guide himself down to the marked area than to control his emotions at the thought of landing on one of the legendary generation ships. But it was likely that his emotional radiation would not inconvenience Prilicla too much because the empath’s feelings would be very similar-even though it was physiologically impossible for a Cinrusskin to experience goose bumps or to have the non-existent hair at the back of its neck prickle with sheer wonder.

            This was one of the generation ships which, before the discovery of hyperdrive, had carried colonists from their home worlds to the planets of other stars. All of the technologically advanced species of what was now the Galactic Federation had gone through their generation-ship phase. Melf, Illensa, Traltha, Kelgia and Earth had been among the scores of cultures which-between the time of their developing chemical- or nuclear-powered interplanetary travel and virtually instantaneous interstellar flight via the hyperdimension

had flung these planetary seed pods into space.

            When a few decades or centuries later the cultures concerned had perfected hyperdrive or received it from one of the species of the emerging Galactic Federation, they had gone looking for these lumbering sub-light-speed behemoths and had rescued the majority of them a few decades or centuries after they had been launched.

            This could be accomplished because the courses of the generation ships were known with accuracy, and their positions at any time during their centuries-long voyages could be computed with ease. Provided no physical or psychological catastrophe had occurred in the meantime-and some of the non-physical things that had gone wrong in the generation ships had given the would-be rescuers nightmares for the rest of their lives-the colonists were transferred to their target worlds within a matter of days rather than centuries.

            Conway knew that the last of the generation ships to be contacted had been cleared, their metal and reactors salvaged. A few of them had been converted for use as accommodation for personnel engaged on space construction projects more than six hundred years ago. But this particular generation ship was one of the few which had not been contacted when hyperdrive was perfected. Either by accident or because of faulty design, it had gone off course to become a seedling destined never to reach fallow ground.

            In silence they landed on the derelict’s hull. Because of the vessel’s slow spin, Conway had to use his feet and wrist magnets to keep from being tossed gently away again, while Prilicla used its gravity nullifiers in combination with magnetic pads on the ends of its six pipe-stem legs. Carefully they climbed through the gap in the plating and out of the direct sunlight. Conway waited until his eyes adjusted to the darkness, then he switched on his suit spotlight.

            There was an irregular natural tunnel in the wreckage, leading down for perhaps thirty meters. At the bottom was a projecting piece of metal, which had been daubed with luminescent green marker paint and a smear of grease.

            "If the Tenelphi’s officers marked a route for you," Fletcher said when Conway reported the find, "it should speed the search for Sutherland. Always provided he hasn’t been diverted from the marked path. But there is another problem, Doctor. The farther you go into the derelict, the more difficult it will be to work your radio signals. We have more power here than you have in your suit power pack, so you will be able to listen to us long after we will cease hearing you. I’m referring to spoken messages, you understand. If you switch on your radio deep inside the ship, we will still be able to hear it, as a hiss or a burst of static, and vice versa. So even if we can no longer talk to each other, switch on your radio every fifteen minutes to let us know you’re still alive, and we’ll acknowledge.

            "It is possible to send messages by short and long bursts of static. It is a very old method of signaling still used in certain emergency situations. Do you know Morse?"

            "No," said Conway. "At least, only enough to send SOS."

            "I hope you don’t have to, Doctor."

            Following the marked path through the wreckage was slow, dangerous work. The residual spin on the derelict made them feel as if they were climbing up towards the center of the ship, while Conway’s eyes and all of his instincts insisted that he was moving downwards. When they reached the first daub of paint and grease, another mark became visible deeper inside the ship, but the path inclined sharply to avoid a solid mass of wreckage and the next leg of the journey angled in a new direction for the same reason. They were progressing towards the center of the ship, but in a series of flat zigzags.

            Prilicla had taken the lead to avoid the risk of Conway falling onto it. With its six legs projecting through its spherical pressure envelope-Prilicla’s bony extremities were not affected by vacuum conditions-it looked like a fat metallic spider picking its way gracefully through a vast, alien web. Only once did its magnetic pads slip, when it began to fall towards him. Instinctively, Conway reached out a hand to check the creature’s slow tumble as it was going past, then pulled his hand back again. If he had gripped one of those fragile legs, it would probably have snapped off.

            But Prilicla checked its own fall with the suit thrusters, and they resumed the long, slow climb.

            Just before communications with the ambulance ship became unworkable, Fletcher reported that they had been gone four hours, and asked if Conway was sure that he was following the missing Sutherland and not just the path marked by the party of the Tenelphi crew-members. Conway looked at the patch of luminous paint just ahead of them, and at the smear of grease beside it, and said he was sure.

            I’m missing something, he told himself angrily, something that is right in front of my stupid face...!

            As they moved deeper into the ship the wreckage became less densely packed, but the apparent gravity pull exerted by the spin had diminished so much that quite large masses of plating, loose equipment and demolished furnishings moved or slipped or settled ponderously whenever they tried to grip them. The suit spotlights showed other things, too-crushed, torn and unidentifiable masses of desiccated organic material, which were the remains of the crew or domestic animals caught in the centuries-old catastrophe. But separating the organic from the metallic wreckage would have been both highly dangerous and a waste of time. Finding Sutherland had to take priority over satisfying their curiosity regarding the physiological classification of the species that had built the ship.

            They had been traveling for just under seven hours and had begun to move through levels that, although their structure was ruptured and contorted, were no longer choked with wreckage. This was fortunate because Prilicla kept blundering gently into walls and bulkheads through sheer fatigue, and every second or third breath that Conway took seemed to turn into a yawn.

            He called a halt and asked the empath if it could detect any emotional radiation apart from Conway’s own. Prilicla said no and was too tired even to sound apologetic. When Conway next heard the periodic hiss in his suit phones, he acknowledged by flipping his transmit switch on and off rapidly three times, pausing, then repeating the signal at short intervals for several minutes.

            The Captain would realize, he hoped, that the repeated S signal meant that Prilicla and Conway were going to sleep.

            They made much better time on the next stage of the journey, which involved simply walking along virtually undamaged decks and climbing broad ramps or narrower stairs towards the center of the ship. Only once did they have to slow to negotiate a plug of wreckage, which had been caused, apparently, by a large and slow-moving meteorite that had punched its way deep inside the ship. A few minutes later they found their first internal airlock.

            Obviously the lock had been built by the survivors after the catastrophe, because it was little more than a large metal cube welded to the surround of an airtight door and containing a very crude outer seal mechanism. Both seals were open and had been that way for a very long time, because the compartment beyond was filled with desiccated vegetation, that practically exploded into dust when they brushed against it.

            Conway shivered suddenly as he thought of the vast ship, grievously but not mortally wounded by multiple meteorite collisions, blinded but not powerless, and with groups of survivors living in little islands of light and heat and isolated by steadily dropping pressure. But the survivors had been resourceful. They had built airlocks, which had enabled them to travel between their islands and cooperate in the matter of life-support, and they had been able to go on living for a time.

            "Friend Conway," said Prilicla, "your emotional radiation is difficult to analyze."

            Conway laughed nervously. "I keep telling myself that I don’t believe in ghosts, but I still won’t believe me."

            They went around the hydroponics room because the markers said that they should, and an hour or so later they entered a corridor that was intact except for two large ragged-edged holes in the ceiling and deck. There was a strange dilution of the absolute darkness of the corridor, and they switched off their spotlights.

            A faint glow was coming from one of the holes, and when they moved to the edge it was as if they were looking down a deep well with a tiny circle of sunlight at the bottom. Within a few seconds the sunlight had disappeared, and for a few more seconds the wreckage at the other end of the tunnel was illuminated. Then the darkness was complete again.

            "Now," Conway said with relief, "at least we know a shortcut back to the outer hull. But if we hadn’t happened to be here at precisely the right time when the sun was shining in-"

            He broke off, thinking that they had been very lucky and that there might be more luck to come, because at the end of the corridor containing the newly discovered exit they could see another airlock. It was marked with luminous paint and a very large smear of grease, and the outer seal was closed, a clear indication that there was pressure in the compartment beyond.

            Prilicla was trembling with its own excitement as well as with Conway’s as Conway began to operate the simple actuator mechanism. He had to stop for a moment because the suit radio was hissing at him and he had to acknowledge. But when he had done so it kept on hissing at him.

            "The Captain is not a very patient man," said Conway irritably. "We’ve been gone just over thirty-eight hours and he said he would give me two days He paused for a moment and held his breath, listening to the faint, erratic hissing, which was quieter than the sound of his own breathing, so deep inside the derelict had they penetrated. It was difficult to tell when a hiss stopped or started, but gradually he detected a pattern in the signals. Three short bursts. Pause. Three long bursts. Pause. Three short bursts, followed by a longer pause, after which the sequence was repeated again and again. A distress signal. An SOS...

            "There can’t be anything wrong with the ship," he said. "That would be ridiculous. So it has to be a problem with the patients. Anyway, they want us back there and I would say the matter is urgent."

            Prilicla, clinging to the wall beside the airlock, did not reply for several seconds. Finally it said, "Pardon the seeming unpoliteness, friend Conway, but my attention was elsewhere. It is at the limit of my range, but I have detected an intelligent life-form."

            "Sutherland!" said Conway.

            "I should think so, friend Conway," Prilicla said. It began to tremble in sympathy with Conway’s dilemma.

            Somewhere within a few hundred feet was the missing Tenelphi medic, physical condition unknown, but very definitely alive. It might take an hour or more to find him, even with Prilicla’s help. Conway desperately wanted to find and rescue the man, not just for the usual reasons but because he felt sure that he possessed the answer to what had happened to the other Tenelphi officers. But he and Prilicla were wanted back on the Rhabwar, urgently. Fletcher would not send an SOS signal without good reason.

            Obviously the ship was not in distress, so it had to be a problem involving the patients. A sudden worsening of their condition, perhaps, which was serious enough for Murchison and Naydrad-two beings who did not panic without reason-to agree to this method of recalling the two doctors. But, thought Conway suddenly, one doctor could satisfy them temporarily until they got two more a little later, one of whom, Sutherland, had a greater knowledge of the malady concerned than the ambulance ship medics.

            Prilicla ceased trembling as soon as Conway made his decision. He turned to his companion. "Doctor, we’ll have to split up. They need us urgently on the ship, or maybe they just want to talk to us urgently. Would you mind taking the shortcut to the outer hull? Find out what the problem is and give what advice you can. But don’t move away from the outer end of that tunnel for at least an hour after you get there. If you do that you will be in line of sight with the Rhabwar and, via the tunnel, with me down here, and can relay messages in either direction.

            "You should be able to get to the other end of the tunnel, with no zigzagging necessary and with the centrifugal force of the spin helping you along, in roughly two hours," Conway went on. "This should give me enough time to find Sutherland and start bringing him out. It has to be my job because it will need DBDG muscles rather than Cinrusskin sympathy to help him through that tunnel."

            "I agree, friend Conway," said Prilicla, already moving along the corridor towards the opening. "I have rarely agreed to a request with more enthusiasm...

            The first surprise when he went through the airlock was that there was light. He found himself in a large, open compartment, which, judging from the remains of equipment attached to the deck, walls and ceiling, had been the ship’s assembly and recreation area. The equipment, which had originally been used for weightless exercising and probably for competitive sports as well, had been drastically modified to provide supports for the sandwich hammocks, which were necessary for sleeping in the weightless condition. Apart from a few sections sheeted in with transparent plastic and containing vegetation, some of which was still green, the interior surfaces of the enormous compartment were covered with bedding and furniture modified for gravity-free conditions. It looked as if up to two hundred survivors of the original meteorite collisions, including their young, had once been packed into this compartment. The visual evidence indicated that they had lived there for a long time. The second surprise was that there were no traces of them other than the furniture and fittings they had used. Where were the bodies of the long-dead survivors?

            Conway felt his scalp prickle. He turned up the volume of his external suit speaker to full and yelled "Sutherland!"

            No response.

            Conway launched himself across the compartment towards the opposite wall, where there were two doors. One of them was partly open and light was shining through. When he landed beside it he knew it was the ship’s library.

            It was not just the neat racks of books and tape-spools that covered the walls and ceiling of the empty room, or the reading and scanning equipment attached to the deck, or even the present-day tapes and portable recorders that had belonged to the Tenelphi officers but that had been abandoned to drift weightlessly about the room. He knew it was the library because he had been able to read the sign on the door, just as he was able to read the name below the ship’s crest mounted at eye-level on the opposite wall. As he stared at that famous crest everything suddenly became clear.

            He knew why the Tenelphi had run into trouble, why the officers had left their ship for the derelict, leaving only their medic as watch-keeping officer. He knew why they had returned so hastily, why they were sick and why there was so little he, or anyone else for that matter, could do for them. He also knew why Surgeon-Lieutenant Sutherland used grease instead of marker paint, and he had a fair idea of the situation confronting the doctor that had driven him back to the derelict. He knew because that ship’s name and crest appeared in the history books of Earth and of every Earth-seeded planet.

            Conway swallowed, blinked away the fog that was temporarily impairing his vision, and backed slowly out of the room.

            The sign on the other door had read Sports Equipment Stowage, but it had been relettered Sick Bay. When he slid it open he found that it, too, was lighted, but dimly.

            Along the walls on both sides of the door, equipment storage shelves had been modified to serve as tiers of bunks, and two of them were occupied. The bodies occupying them were emaciated to the point of deformity, partly because of malnutrition and partly because of being born and living out their lives in the weightless condition. Unlike the desiccated sections of bodies Prilicla and he had encountered on the outer decks, these two had been exposed to atmosphere, and decomposition had taken place. The process was not sufficiently advanced, however, to conceal the fact that the bodies were of classification DBDG, an old male and a girl-child, both Earth-human, and that their deaths had occurred within the past few months.

            Conway thought of the voyage that had lasted nearly seven centuries and of the last two survivors who had almost made it, and he had to blink again. Angrily, he moved deeper into the room, pulling himself along the edge of a treatment table and instrument cabinet. In a far corner his spotlight illuminated a spacesuited figure holding a squarish object in one hand and supporting itself against an open cabinet door with the other.

            "S ... Sutherland?"

            The figure jerked and in a weak voice replied, "Not so bloody loud."

            Conway turned down the volume of his speaker and said quickly, "I’m glad to see you, Doctor. I’m Conway, Sector General. We have to get you back to the ambulance ship quickly. They’re having problems there and..

            He broke off because Sutherland was refusing to let go of the cabinet. Reassuringly, Conway went on: "I know why you used yellow grease instead of paint, and I haven’t unsealed my helmet. We know there is pressure in other parts of the ship. Are there any survivors? And did you find what you were looking for, Doctor?"

            Not until they were outside the sick bay with the door closed behind them did Sutherland speak. He opened his visor, rubbed at the moisture beading the inside of it. "Thank God somebody remembers his history," he said weakly. "No, Doctor, there are no survivors. I searched the other air-filled compartments. One of them is a sort of cemetery of inedible remains. I think cannibalism was forced on them at the end, and they had to put their dead somewhere where they would be, well, available. And no again, I didn’t find what I was looking for, just a means of identifying but not curing the condition. All the indicated medication spoiled hundreds of years ago He gestured with the book he was holding. "I had to read some fine print in there, so I increased the air pressure inside my suit so that when I opened my visor for a closer look it would blow away any airborne infection. In theory it should have worked."

            Obviously it had not worked. In spite of the higher pressure inside his suit blowing air outwards through his visor opening, the Surgeon-Lieutenant had caught what his fellow officers had. He was sweating profusely, squinting against the light and his eyes were streaming, but he was not delirious or unconscious, as the other officers from the Tenelphi had been. Not yet.

            "We found a quick way out," Conway said. "Well, relatively. Do you think you can climb with my assistance, or should I tie your arms and legs and lower you ahead of me?"

            Sutherland was in poor shape, but he most emphatically did not want to be tied and lowered, no matter how carefully, down a tunnel whose walls were of twisted and jagged-edged metal. They compromised by strapping themselves together back to back, with Conway doing the climbing and the other medic fending them off the obstructions Conway could not see. They made very good time, so much so that they had begun to catch up to Prilicla before the Cinrusskin was more than halfway along the tunnel. Every time the sun shone into the other end, the dark circle that was the empath’s spacesuited body seemed larger.

            The continuous hissing of the SOS signal grew louder by the minute, then suddenly it stopped.

            A few minutes later the tiny black circle that was Prilicla became a shining disk as the empath cleared the mouth of the tunnel and moved into sunlight. It reported that the Rhabwar and the Tenelphi were in sight, and that there should be no problem making normal radio contact. They heard it calling the Rhabwar, and what seemed like ten years later came the hissing and crackling sound of the ambulance ship’s reply. Conway was able to make out some of the words through the background mush, so he was not completely surprised by Prilicla’s relayed message.

            "Friend Conway," said the empath, and he could imagine it trying desperately to find some way of softening the effect of its bad news. "That was Naydrad. All the DBDG Earth-humans on the ship, including Pathologist Murchison, are displaying symptoms similar to those of the Tenelphi officers, with varying degrees of incapacity. The Captain and Lieutenant Chen are the least badly affected so far, but both are in a condition that warrants their being confined to bed. Naydrad requires our assistance urgently, and the Captain says he’ll leave without us if we don’t hurry up. Lieutenant Chen is doubtful about our leaving at all, even if they weren’t having to modify the hyperdrive envelope to accommodate the Tenelphi. It seems there are additional problems caused by the proximity of the system’s sun that require a trained astrogator to-"

            "That’s enough," Conway broke in sharply. "Tell them to dump the Tenelphi! Decouple and undock and jettison any samples Chen took aboard for analysis. Neither Sector General nor the Monitor Corps will thank us for bringing back anything that has been in contact with the derelict. They might not be too happy to see us- He broke off as he heard Naydrad’s voice relaying his instructions to the Captain and the beginning of Fletcher’s reply. He went on quickly: "Prilicla, I’m receiving the ship direct, so I don’t need you as a relay anymore. Return to the ship as quickly as possible and help Naydrad with the patients. We should be clear of this tunnel in fifteen minutes. Captain Fletcher, can you hear me?"

            A voice which Conway did not recognize as the Captain’s said, "I can hear you."

            "Right," said Conway, and very briefly he explained what had happened to the Tenelphi and themselves...

            Finding a derelict in the system they were surveying had been a welcome break in the monotony for the scoutship and for the offduty officers who went on board to investigate and, if possible, identify the vessel. Like all scoutships on survey duty, the Tenelphi had a complement consisting of a Captain and his astrogation, communications, engineering and medical officers, while the remaining five were the survey specialists, whose work went on around the clock.

            According to Sutherland, the first officers to board the derelict had identified the ship very quickly, because of a lucky find of a store requisition form, dated and headed with the ship’s crest. The result had been that everyone, including the Captain, had hastily transshipped to the derelict. The sole exception was the ship’s medic, whose specialty was considered the least useful on what had suddenly become a mass information-gathering exercise.

            For the derelict was none other than the Einstein, the first starship to leave Earth and the only one of those early generation ships from that planet not to be rescued by the later hyperdrive vessels. Many attempts at rescuing it had been made over the centuries, but the Einstein had not followed its intended course. It had been assumed that the ship had suffered a catastrophic malfunction within a relatively short time of leaving the solar system.

            And now here it was, the first and undoubtedly the bravest attempt by mankind to reach the stars the hard way, because at that time its technology had been untried, because nobody knew with absolute certainty that its target system contained habitable planets, and because its crew, the very best people that Earth could produce, wanted to go anyway. As well, the Einstein was a piece of technological and psychosociological history, the embodiment of one of the greatest legends of star travel. Now this great ship with its priceless log and records was falling into the sun and would be destroyed within the week. Small wonder, therefore, that the Tenelphi was left with only its medical officer on board. But even he did not realize that there was any danger in the situation until the crew, sick and sweating and near delirium, began to return. From the onset Sutherland had discarded Conway’s first assumptions, that their condition was due to radiation poisoning, inhaling toxic material or eating infected food, because the returning officers told him about the conditions on board the derelict and how long some of the descendants of its crew had been able to survive.

            Not only did the ship carry priceless records of man’s first attempt at interstellar flight, it also contained an unknown quantity and variety of bacteria-preserved by the heat and atmosphere and recently living human organisms-of a type which had existed seven hundred years ago and for which the human race no longer had immunity.

            Noting the rapidly worsening condition of his fellow officers and knowing there was little he could do for them, Sutherland insisted that they all wear spacesuits continually to avoid the possibility of cross-infection-he could not be absolutely sure they were all suffering from the same disease-and as protection in case of accidents while they were moving clear of the derelict. Their intention was to Jump to Sector General, where some high-powered medical assistance would be available.

            When the collision-the inevitable collision, according to Sutherland, considering the semi-conscious and delirious condition of the crew-occurred, he moved the men to the lock antechamber in preparation for a quick evacuation, tried to send a subspace radio signal, and not knowing if he was doing the job properly, tried to eject the distress beacon. But the collision had damaged the release mechanism, and he had to push it out of the airlock. His patients’ condition was worsening, and he wondered again if there was anything at all that he could do for them.

            It was then that he decided to go aboard the derelict himself, to look for a cure in the very place the disease had originated. The solution might be in the derelict’s medicine chest, the "sin chest" of the garbled radio signal. With pressure dropping steadily aboard the badly damaged Tenelphi and all the recorders abandoned on the derelict, he could not leave a proper warning for any would-be rescuers. But he had done his best.

            He had smeared the Tenelphi’s airlock outer seal with yellow grease, not knowing that the heat from the distress beacon would turn it brown, and he had marked his path through the derelict in similar fashion. Few people these days realized, and even Conway had been slow to remember, that in pre-space-travel times a ship with disease on board flew a yellow flag...

            "Sutherland discovered that the medication in the Einstein’s sick bay had long since spoiled," Conway went on, "but he did find a medical textbook which mentioned a number of diseases with symptoms similar to those shown by our people. It is one of the old influenza variants, he thinks, although in our case the loss of natural immunity over the centuries means that these symptoms are being experienced with much greater severity, and any prognosis would be uncertain. That is why I would like you to record this information for proper subspace transmission to Sector General, so that they will know exactly what to expect. And I suggest you make preparations for an automatic Jump, in case you aren’t feeling well enough to-"

            "Doctor," the Captain replied weakly, "I’m trying to do just that. How quickly can you get back here?"

            Conway remained silent for a moment while he and Sutherland cleared the edge of the tunnel. "I have you in sight. Ten minutes."

            Fifteen minutes later Conway was removing Sutherland’s spacesuit and uniform on the Casualty Deck, which was rapidly becoming overcrowded. Doctor Prilicla was hovering over the patients in turn, keeping an eye and an empathic faculty on their condition, while Naydrad brought in Lieutenant Haslam, who had collapsed at his position in Control a few minutes earlier.

            Neither of the extraterrestrials had anything to fear from terrestrial pathogens, even seven-hundred-year-old pathogens. The Tenelphi and Rhabwar crew-members and Murchison could only lie and hope, if they weren’t already delirious or unconscious, that their bodies’ defenses would find some way of fighting this enemy from the past. Only Conway had remained free from infection, because a smear of grease or something in a garbled radio signal had worried his subconscious to the extent that he had not unsealed his visor after the scoutship’s officers had been brought aboard.

            "Four-G thrust in five seconds," came Chen’s voice from the speaker. "Artificial gravity compensators ready."

            The next time Conway looked at the repeater screen it showed the Einstein and the Tenelphi shrunk to the size of a tiny double star. He finished making Sutherland as comfortable as possible, checked his IVs and moved on to Haslam and Dodds. He was leaving Murchison to the last, because he wanted to spend more time with her.

            She was perspiring profusely despite the reduced temperature inside the pressure litter, muttering to herself and turning her head from side to side, eyes half-open but not really conscious of his presence. He was shocked to see Murchison like this. He realized that she was a very seriously ill patient instead of the colleague he had loved and respected since the days when she was a nurse in the FGLI maternity section, when he was convinced that all the ills of the Galaxy could be cured by his pocket x-ray scanner and his dedication to his profession.

            But in Sector General, where the lowliest member of the medical staff would be considered a leading authority in a single-species planetary hospital, all things were possible. An able nurse with wide e-t experience could move up and across the lines of promotion to become one of the hospital’s best pathologists, and a junior doctor with unconventional ideas bubbling about in a head that was much too large could learn sense. Conway sighed, wanting to touch and reassure her. But Naydrad had already done all that it was possible to do for her, and there was nothing he could do except watch and wait while her condition deteriorated towards that of the Tenelphi officers.

            With any luck they would soon be transferred to the hospital, where more high-powered help and resources were available. Fletcher and Chen had been lucky in that the Captain had been in Control and the engineer officer in the Power Room while the infected Tenelphi officers were being brought aboard, so they had been the last two to be affected. Fortunately, they were still fit enough to work the ship.

            Or were they...

            The repeater screen was still showing an expanse of blackness in which the Einstein and the Tenelphi were indistinguishable among the background stars. But by now the screen should be showing the non-color of the hyperdimension. It would be much better for all concerned, Conway thought suddenly, if he stopped doing nothing for Murchison and tried to do something for Chen and the Captain.

            "Friend Conway," said Prilicla, indicating with one of its feelers, "would you look at this patient, please, and at the one over there? I feel they are conscious and need reassurance by a member of their own species."

            Ten minutes later Conway was in the well, pulling himself towards Control. As he entered he could hear the voices of the Captain and engineer officer calling numbers to each other, with frequent stops for repeats and rechecks. Fletcher’s face was red and dripping with perspiration, his eyes were streaming and his delirium seemed to have taken the form of a rigid professional monomania as he blinked and squinted at the displays on his panel and read off the numbers. Meanwhile, Chen, who did not look much better, replied from the strange position of the astrogator’s panel. Conway regarded them clinically and did not like what he saw.

            "You need help," he said firmly.

            Fletcher looked up at him through red-rimmed, streaming eyes. "Yes, Doctor, but not yours. You saw what happened to the Tenelphi when the medical officer tried to pilot it. Just tend to your patients and leave us alone."

            Chen rubbed sweat from his face. "What the Captain is trying to say, Doctor, is that he can’t teach you in a few minutes what it took him five years of intensive training to learn, and that the delay in making the Jump is caused by our having to get it right first time in case we aren t fit enough for a second try and we materialize in the wrong galactic sector, and that he is sorry for his bad manners but he is feeling terrible."

            Conway laughed. "I accept his apology. But I have just come from speaking to one of the Tenelphi victims of what we now feel sure is one of the old influenza variants. He was one of the first to fall sick along with the other member of the original boarding party. Now his temperature is returning to normal and that of the other one is also falling rapidly. I would say that this outbreak of sevenhundred-year-old flu can be treated successfully with supportive medication, although the hospital will probably insist on a period of quarantine for all of us when we get back.

            "However," he went on briskly, "the officer I speak of is the Tenelphi’s astrogator, and frankly, he is in much better shape than either of you two. You do need help?"

            They were looking at him as if he had just produced a miracle, as if in some peculiar fashion Conway was solely responsible for all the complex mechanisms evolved by the DBDG Earth-human lifeform to protect itself against disease-which was, of course, ridiculous. He nodded to them and returned to the Casualty Deck to send up the Tenelphi astrogator. He was thinking that within two weeks at most, everyone apart from the immune Prilicla and Naydrad would be fully recovered and convalescent, and he would no longer have to treat Pathologist Murchison as a patient.

PART 3

QUARANTINE

Immediately on its return to Sector General, the Rhabwar and the I Earth-human personnel on board were placed in strict quarantine and refused admission to the hospital. Conway, who had had no direct physical contact with either the Tenelphi’s or his ambulance ship’s crews since the infection had come aboard, was doubly quarantined in that he inhabited the man-shaped bubble of virus-free air that was his long-duration spacesuit and a cabin hastily modified to provide life-support independent of the ship’s infected system.

            There was no real problem in providing supportive treatment to both crews-who were either responding well or were in varying stages of convalescence-because he had Prilicla and Naydrad assisting him. As extraterrestrials they were, of course, impervious to Earth-human pathogens, and they were being very smug about this. Neither was there any difficulty in accommodating the two crews- the officers of the Tenelphi occupied the Casualty Deck, and the ambulance ship personnel had their own cabins. But there were periods, often as long as twenty-three hours in the day, when the Rhabwar was dreadfully overcrowded.

            The real problem was that while the hospital refused them admittance, practically every Earth-human and e-t in Sector General was trying to find an excuse to visit the ambulance ship.

            During the first week, combined medical and engineering teams worked around the clock flushing out the ship’s air system and sterilizing everything with which the infected air had come in contact. There were also constant checks on the progress of the patients and constant supervision of the regimen, which would ensure that after their cure was effected they would not retain the ability of passing on the infection to any other member of the Earth-human DBDG classification. Lastly, there were those who came simply to talk to the patients and complain about Conway’s handling of the Einstein incident.

            These included Thornnastor, the elephantine Tralthan Diagnostician in charge of the Pathology Department, who came chiefly to raise the morale of its department-member Murchison by providing her with the latest hospital gossip, which in some of the e-t wards was colorful; and a variegated bunch of highly professional medics and bitterly disappointed amateur historians who wanted to talk to the Tenelphi crew about their experiences aboard the derelict, and to castigate Conway for not bringing back more in the way of specimens than a seven-hundred-year-old medical textbook, which had fallen apart as soon as it was exposed to present-day sterilization techniques.

            Inside his suit-shaped bubble of sterile air, Conway tried, not always successfully, to remain emotionally cool and aloof. Captain Fletcher, whose convalescence had advanced to the stage where he was convinced that medical red tape was all that was keeping him from resuming active duty, could not remain cool at all. Especially when the Rhabwar personnel gathered together at mealtimes.

            "You are a senior physician, after all, and you are still the ranking medical officer on this ship," the Captain observed in an aggrieved tone while he attacked the rather bland meal the hospital dietitians had prescribed for them. "Unlike us, Doctor, you never were a patient, so your rank was not taken away when you were issued a hospital gown. I mean, Thornnastor is all right as a person, but it’s an FGLI, after all, and its movements are about as graceful as those of a six-legged baby elephant. Did you see what it did to the ladder on the Casualty Deck, and to the door of your cabin, ma’am?"

            He broke off to smile admiringly at Murchison. Lieutenant Haslam muttered something about often feeling like breaking down the pathologist’s door himself, and the Captain silenced him with a frown. Lieutenants Dodds and Chen, like the good junior officers they were, maintained a respectful silence, and in common with the other male Earth-human DBDGs present, exuded minor-key emotional radiation of a pleasurable nature, which Prilicla would have described as being associated with the urge to reproduce. Charge Nurse Naydrad, who rarely allowed anything to interfere with bodily refueling, kept on moving large portions of the green and yellow vegetable fiber it was pleased to call food, and ignored them.

            The emotion-sensitive Doctor Prilicla, who could ignore nobody, hovered silently above the edge of the table, showing no signs of emotional distress. Obviously the Captain was not as irritated as he sounded.

            ..... Seriously, Doctor," Fletcher went on, "it isn’t just Thornnastor blundering into areas of the ship that were not meant for FGLIs. Some of the other e-ts take up a lot of space as well, and there are times when each crew-member of the Tenelphi has about half a dozen e-ts or Earth-humans sitting at his feet while he chatters on and on about the things he saw on that derelict, and they treat us as if we’d caught a mutated form of leprosy instead of the same influenza virus as the scoutship crew."

            Conway laughed. "I can understand their feelings, Captain. They lost material of priceless historic value, which was already considered irretrievably lost for many centuries. That means they have lost it twice and feel twice as angry with me for not bringing back an ambulance shipful of records and artifacts from the Einstein. At the time I was tempted. But who knows what else I might have brought back with those records in the way of seven-hundred-year-old bacterial and viral infections from which we have little or no immunity? I couldn’t take the risk, and they, when they stop being bitterly disappointed amateur historians and go back to being the hospital’s top seniors and Diagnosticians, will know that, given the same circumstances, they would have done exactly what I did."

            "I agree, Doctor," said Fletcher, "and I sympathize with your problem and theirs. I also know that they have to undergo a very thorough and, well, physically inconvenient decontamination procedure on leaving the ship, regardless of their physiological classifications, and this weeds out all but the most enthusiastic or masochistic amateur historians. All I want to know is whether there is a polite way, or any way, of telling them to stay off my ship."

            "Some of them," said Conway helplessly, "are Diagnosticians."

            "You say that as if it was some kind of answer, Doctor," said the Captain, looking perplexed. "What is so special about a Diagnostician?"

            Everyone stopped eating to look at Conway, who alone among them could not eat anywhere outside his sterile cabin. Prilicla’s hover became somewhat unstable, and Naydrad gave a short foghorn blast that was untranslatable but was probably the Kelgian equivalent of a snort of incredulity.

            It was Murchison who finally spoke. "The Diagnosticians are very special, Captain," she said. "And peculiar. You already know that they are the top-ranking medical personnel in the hospital, and as such, cannot be readily ordered around. Another reason is that when you speak to one of them you can never be sure who or what you are talking to..."

            Sector General was equipped to treat every known form of intelligent life, Murchison explained, but no single person could hold in his or its brain even a fraction of the physiological data necessary for this purpose. Surgical dexterity and a certain amount of e-t diagnostic ability came with training and experience, but the complete physiological knowledge of any patient requiring complex treatment was furnished by means of an Educator tape. This was simply the brain recording of some great medical authority belonging to the same species as or a species similar to that of the patient undergoing treatment.

            If an Earth-human doctor had to treat a Kelgian patient, he took a DBLF physiology tape until treatment was completed, after which the recording was erased from his mind. The sole exceptions to this rule were senior physicians with teaching duties, which required the retention of one or two tapes, and the Diagnosticians.

            A Diagnostician was one of the hospital elite, a being whose mind was considered stable enough to retain six, seven, and in a few cases, ten physiology tapes simultaneously. To these datacrammed minds were given projects such as original research in xenological medicine and the treatment of new diseases in hitherto unknown life-forms.

            But the tapes did not impart only physiological data. Rather, the complete memory and personality of the entity who had possessed that knowledge was transferred as well. In effect, a Diagnosticianan subjected himself or itself voluntarily to the most drastic form of schizophrenia. The entities apparently sharing a Diagnostician’s mind could well be aggressive, unpleasant individuals-geniuses, whether medical or otherwise, were rarely pleasant people-with all sorts of peeves and phobias.

            The original personality was never submerged completely, but depending on the case or research project currently being worked on and the depth of concentration required for it, one could never be sure of a Diagnostician’s reaction to any request that was not of a medical nature. Even then it was considered good manners to find out who or what kind of personality was in partial mental control of the entity concerned before saying anything at all. As a class they were not people one gave orders to, and even the hospital’s Chief Psychologist O’Mara had to treat them with a certain degree of circumspection.

            ..... So I’m afraid you can’t just tell them to go away, Captain," Murchison went on, "and the seniors accompanying those Diagnosticians will have sound medical reasons, as well as non-medical ones, for being here. You should also remember that for the past two weeks they have been checking us practically cell by cell, and they might become even more thorough if we were to suggest that they stop wasting time talking history to the scoutship crew and-"

            "Not that," said the Captain hurriedly, and sighed. "But Thornnastor seems a friendly enough being, if a bit big and awkward, and it is our most frequent visitor. Could you suggest to it, ma’am, that if it came less often and without its medical retinue. . .

            Murchison shook her head firmly. "Thornnastor is Diagnosticianin-Charge in Pathology and as such is the hospital’s senior Diagnostician. It is also a source of news, a friend, and my head of department. Anyway, I enjoy Thorny’s visits. You may think it odd that a Tralthan FGLI, an oversized, elephantine, six-legged, warmblooded oxygen-breather with four manipulatory appendages and more eyes than seems decent should relish discussing a juicy piece of gossip from the SNLU section of the methane wards. You may even wonder how anything of a scandalous nature could occur between two intelligent crystalline entities living at minus one hundred and fifty degrees centigrade, or why their off-duty activities are of such interest to a warm-blooded oxygen-breather. But you must understand that Thorny’s feeling for other e-ts, and even for us Earth-humans, is unique. It is, you see, one of our most stable and well-integrated multi-personalities . .

            Fletcher held up both hands in a gesture of surrender. "As well as possessing the ability to instill a degree of personal loyalty in its staff, which is unusual, to say the least. All right, ma’am, you’ve convinced me. I am no longer ignorant about Diagnosticians, and I can do nothing about their overrunning my ship."

            "I’m afraid not, Captain," Murchison agreed sympathetically. "Only O’Mara could do something about that. But he is very fond of his Diagnosticians and of saying that any being sane enough to be a Diagnostician is mad. .

            While Murchison and Fletcher had been speaking, the illumination in the dining compartment had undergone a subtle change, caused by the vision screen lighting up to show the craggy features of the Chief Psychologist.

            "Why is it that every time I break in on a conversation I find people talking about me," O’Mara asked sourly. "But don’t apologize or explain; you would strain my credulity. Conway, Fletcher, I have news for you. Doctor, you can discard that spacesuit, reconnect your cabin to the ship’s air system, and resume eating and direct physical contact with your colleagues." He smiled faintly, but did not look at Murchison as he went on. "The ship has been cleared as free from infection, but frankly, this business has uncovered a serious weakness in patient reception procedures.

            "Up until now," he continued, "we have assumed, and rightly, that new patients or casualties pose no threat because e-t pathogens cannot affect entities of another species. And because any being traveling in space, even on an interplanetary hop, has to undergo strict health checks, we tended to be a bit lax regarding same-species infections. That is why we are being very cautious and are allowing only the Tenelphi crew off the ship while the rest of you must stay aboard the Rhabwar for another five days. They caught the disease first, then the ambulance ship crew did; if you don’t come down with symptoms during the next five days, then your ship and everyone on it is clear. However, to keep you and everyone else from feeling bored with inaction we have a job for you. Captain Fletcher, you and your officers are returned to active duty. How soon can you be ready to leave?"

            Fletcher tried hard not to show his eagerness as he replied: "We have been unofficially on active duty for the past week and the ship is ready, Major. Provided we can have immediate action in the matter of topping up stores and medical consumables and there are no oversized e-ts getting underfoot-"

            "That I can promise," said O’Mara.

            -we can take off within two hours," Fletcher ended.

            "Very well," replied the Chief Psychologist briskly. "You will be answering a distress beacon detected in Sector Five, well out on the rim. The radiation signature of the beacon indicates that it is not one of ours. There is no Federation traffic out there anyway, and the star destiny is so low that we didn’t waste time trying to chart the area ourselves. But if there is a star-traveling race out there, they might let us copy their charts when we show them ours. Especially if you bail some of their friends out of trouble. Or perhaps I should not remind highly altruistic medical types like yourselves of the mutual profit aspect of this situation. Communications Center will let you have the coordinates of the beacon presently. The probability of this distress signal originating from a ship of a hitherto undiscovered species is close to being a certainty.

            "And Conway," O’Mara ended dryly, "this time try to bring back a few ordinary, or even extraordinary, casualties, and not a potential epidemic..

            *           *           *

They wasted no time moving out to Jump distance because Fletcher was now fully confident of the capabilities of his ship. He did complain a little, although it seemed to Conway to be more in the nature of an apology, about the tuition during the first mission and this one. Theoretically, his officers and the medical team were supposed to become less specialized in their functions.

            According to the ambulance-ship project directive, Conway was supposed to teach his officers the rudiments of e-t physiology, their physical structures, musculatures, circulatory systems and so on- enough of the subject, at least, for them not to kill some hapless casualty through good intentions. Meanwhile, Fletcher was supposed to reciprocate by lecturing the medical team on his particular specialty, e-t ship design and comparative technology, so that they would not make elementary errors regarding the vessel surrounding their patient.

            Fletcher agreed with Conway that there would be no time to set up the lecture program on this mission, but that they would keep it in mind for the future. The result was that Conway spent most of the time in hyperspace with Naydrad, Prilicla and Murchison on the Casualty Deck, wondering whether they were properly prepared to receive an unknown number of casualties of an unknown physiological type. But he was in Control, at Fletcher’s invitation, just before they were due to emerge.

            A few seconds after the Rhabwar emerged into normal space, Lieutenant Dodds announced, "Wreckage ahead, sir."

            "I don’t believe...!" Fletcher began incredulously. "The accuracy of your astrogation is much too good, Dodds, to be due to anything but sheer luck."

            "Oh, I don’t know, sir," Dodds replied, grinning. "Distance is twelve miles. I’m locking on the scope now. You know, sir, this could be the fastest rescue ever recorded."

            The Captain did not reply. He was looking pleased and excited and a little bit wary of so much good luck. On the screen the wreckage showed as a flickering gray blur spinning rapidly in the blackness. Out here on the Rim the stellar density was low, and most of the available light came from the long, faintly shining fog bank, which was the parent galaxy. Suddenly the image became brighter but even more blurred as Dodds switched to the infrared receptors and they saw the wreckage by its own heat radiation.

            "Sensors?" the Captain asked.

            "Non-organic material only, sir," Haslam reported. "No atmosphere present. Relative to the ambient temperature, it is very warm, suggesting that whatever happened occurred recently and probably as a result of an explosion.~~

            Before the Captain could reply, Dodds said, "More wreckage, sir. A larger piece. Distance fifty-two miles. Spinning rapidly."

            "Give me the numbers for closing with the larger piece," Fletcher ordered. "Power Room. I want maximum thrust available in five minutes."

            "Three more pieces," said Dodds. "Large, distance one hundred plus miles, widely divergent bearings, sir,"

            "Show me a distribution diagram," said the Captain, responding quickly. "Compute courses and velocities of all the pieces of wreckage, with a view to tracing the original point of the explosion. Haslam, can you tell me anything?"

            "Same temperatures and material as the other pieces, sir," Haslam reported. "But they are at the limit of sensor range, and I could not say with certainty that it is composed entirely of metal. None of the pieces encloses an atmosphere, even residual."

            "So if organic material is present," said Fletcher grimly, "it is no longer alive."

            "More wreckage, sir," said Dodds.

            This is not going to be a fast rescue, thought Conway. It might not even be a rescue at all.

            Fletcher must have been reading Conway’s mind, because he pointed at the big repeater screen. "Don’t give up hope, Doctor. The first indications are that a ship has suffered a catastrophic explosion, and the distress beacon was released automatically as a result of the malfunction and not by one of the survivors, if any. But look at that display..

            The picture on the screen did not mean very much to Conway. He knew that the winking blue spot was the Rhabwar and that the white traces that were appearing every few seconds were wreckage detected by the ship’s expanding radar and sensory spheres. The fine yellow lines that converged at the center of the screen were the computed paths taken by the wreckage from the point of the explosion, and what should have been a simple picture was confused by groups of symbols and numbers that flickered, changed or burned steadily beside every trace.

            The distribution of the wreckage seems a bit lopsided for an explosion," Fletcher went on, "and although the scale is too small for it to be apparent on the screen, it appears to have originated from a short, flat arc rather than a point. Then, there is the virtually uniform rate of spin on the pieces of wreckage, and their relatively small number and large size. When a ship is torn apart by an explosion, usually caused by a power-reactor malfunction, debris size is small and the rate of spin negligible. Also, the temperature of this wreckage is too low for it to have originated in a reactor explosion, which we now know would have to have occurred less than seven hours ago.

            "The probability is," the Captain ended, "that it was a hyperdrive generator malfunction, Doctor, and not an explosion."

            Conway tried to control his irritation at the other’s lecturing and faintly condescending tone, realizing that the Captain could not help his academic background. Conway knew that if one of a matched set of hyperdrive generators was to fail, the other was supposed to cut out automatically; the vessel concerned would emerge suddenly into normal space somewhere between the stars, and sit there, unable to make it home on impulse drive, until either it repaired the sick generator or help arrived. But there had been instances when the safety cutoff on the good generator had failed or had been a split second late in functioning, which meant that a part of the ship had been proceeding at hyperspeed while the rest had been slowed instantaneously to sublight velocity. The effect on the vessel concerned was, at best, only slightly less catastrophic than a reactor explosion-but at least there would be no heat fusion, radiation and the other complications of a reactor blowup to worry about. The chance of finding survivors was very slightly increased.

            "I understand," said Conway. He flipped the intercom switch on his console and said, "Casualty Deck, Conway here. You may stand down. Nothing will be happening for at least two hours."

            "That is a pretty accurate estimate," Fletcher said dryly. "Since when have you become an astrogator, Doctor? Never mind. Dodds, compute a course linking the three largest pieces of wreckage, and put the figures on the Power Room repeater. Chen, we will apply maximum thrust in ten minutes. To save time I plan to make a close pass of the likeliest prospects and decelerate only if Haslam’s sensors or Doctor Prilicla’s empathy say it is worth doing so. Haslam, stay on the sensors and pick out a few more possibilities for us to look at once we’ve checked the first three. And continue searching the radio frequencies in case a survivor is trying to attract our attention in that fashion, and keep an eye on your scope in case it is trying to flash a light at us."

            As Conway was leaving the Control Deck to rejoin his medical team aft, Haslam said in a quiet, respectful voice, "I’ve only got two eyes, sir, and they don’t swivel independently..

            One hour and fifty-two minutes later they passed heartstoppingly close to the first piece of wreckage. The sensors had already reported negatively on it-no organic material present other than structural plastic trimming panels and furniture, no pockets of atmosphere that might have contained a living entity. When they tried to put a tractor beam on it to check its spin, the whole mass began to fly apart and they had to take violent evasive action.

            They caught up with the next piece in less than an hour. They had to decelerate and return to it, because the sensors reported small pockets of atmosphere inside the wreckage and organic material of a non-structural but not necessarily still-living kind. This time they did not risk trying to check its spin in case the loose mass of wreckage fell apart and the potentially life-giving pockets of air were lost to space. Instead, they set the sensor and vision recorders going during their slow, careful and extremely close approach. The close approach was for Prilicla’s benefit, but the empath reported apologetically that none of the organic material was alive.

            They had three hours to study the recordings before reaching the third piece of wreckage, which was the largest and most promising to be detected. In the process they learned quite a lot about the design philosophy of the alien ship-builders from the way the structural members and bulkheads had been twisted apart by the accident. The dimensions of the corridors and compartments gave an indication of the size of the life-forms that had crewed the ship. They had glimpses of things that looked like thick pieces of manycolored fur trapped and partially hidden in the wreckage. It might have been floor covering or bedding, except that a few of the pieces were restrained by webbing and many of them showed patches of reddish brown, which looked very much like dried blood.

            "Judging by the color of those stains," Murchison observed as they studied one of the stills on the Casualty Deck repeater, "the chances are pretty good that they are warm-blooded oxygen-breathers. But do you think anyone could survive a disaster like that?"

            Conway shook his head but tried to sound optimistic. "The staining on the fur does not appear to be associated with lacerations or punctured wounds of the kind suffered through violent deceleration or collision when the restraining body harness becomes deeply embedded in the body it was meant to protect. From these pictures it is impossible to tell which end of the body is which, but the staining seems to be located in the same areas of all the bodies. This suggests explosive decompression and the exiting of body fluid through natural openings, rather than massive external injury due to a sudden deceleration or collision. None of these people was wearing spacesuits, but if any of them was fast enough or lucky enough to be wearing suits, they should have been able to survive."

            Before Murchison could reply the picture changed abruptly to show another mass of wreckage, and the excited voice of the Captain sounded from the wall speaker. "This looks like the best bet so far, Doctor. No spin to speak of, so we can board easily, if necessary. The fog you see is not all escaped air; some of it is boil-off from the vessel’s water and hydraulic systems. If air is escaping, then there must be quite a lot of it still left on board. There is also what seems to be an emergency power circuit in use, weak and probably used for standby lighting. We may want to board this one. Is everyone ready?"

            "Ready, friend Fletcher," said the empath.

            "Of course," said Naydrad.

            "We’ll be at the Casualty lock in ten minutes," said Conway.

            "Lieutenant Dodds and myself will accompany you,’ said the Captain, "in case structural or engineering problems are encountered. Ten minutes, Doctor."

            There was not a lot of room to spare in the Casualty airlock with the Captain, Dodds, Naydrad and its already inflated pressure litter, Prilicla and Conway all clinging to its deck and walls with foot and wrist magnets while they watched the approach of the wreckage. It looked like a great rectangular metal thicket shrouded in fog and surrounded by smaller clumps of metal, some of which were spinning rapidly and some of which drifted motionless. When Conway asked why this should be, the Captain turned silent in the manner of a person who has asked himself the same question and was unable to answer. They waited while the ambulance ship edged closer, passing between two of the wreckage’s madly spinning satellites, and their suit spotlights as well as those of the ship reflected off the twisted metal plating and projecting structural members. They went on waiting until the little Cinrusskin began trembling inside its spacesuit.

            "Someone," Prilicla finally managed to utter, "is alive in there."

            Of necessity, it was a hurried but very careful search, because the emotional radiation of the survivor was weak and characteristic of a mind that was becoming more deeply unconscious by the minute. With Prilicla indicating if not leading the way, the Captain and Dodds cleared a path through obstructions with their cutters or pushed away free-floating debris and tangled cable looms with their insulated gauntlets-there was, after all, a live power circuit in use. Conway followed closely behind, pulling himself along in a kind of weightless crawl through corridors and compartments whose ceilings were only four feet high.

            Twice his spotlight picked out the bodies of crew-members, which he freed and pushed gently back the way they had come so that the waiting Naydrad could load them into the unpressurized section of the litter. Should the survivor need urgent surgical attention, Conway would feel much better if Murchison had a few cadavers to take apart so that she could tell him how the living one should be put together again.

            He still had no clear idea of what they looked like, because the bodies had been encased in spacesuits. But the suits and underlying tissue had been ruptured by violent contact with metallic debris, and if the resulting wounds had not killed the beings, the decompression had. Judging by the shape of the spacesuits, the beings were flattened cylinders about six feet long with four sets of manipulatory appendages behind a conical section that was probably the head, and another four locomotor appendages. There was a marked thickening at what was presumably the rear section of the suit. Apart from the smaller size and number of appendages, the beings physically resembled the Kelgian race, to which Naydrad belonged.

            Conway could hear the Captain muttering to himself about the spacesuited aliens as they stopped at the entrance to a compartment that retained pressure. Prilicla felt carefully with its empathic faculty for the presence of life, in vain. The survivor was located somewhere beyond the compartment, the empath said. Before the Captain and Dodds burned away the door, Conway drilled through to obtain an atmosphere sample for Murchison so that she could prepare suitable life-support for the survivor.

            Inside the compartment there was light-a warm, orange light, which would give important information about the planet of origin and the visual equipment of this species. But right then it illuminated only a shambles of drifting furniture, twisted wall plating, tangles of plumbing, and aliens, some of whom were spacesuited and all of whom were dead.

            The thickened section at the rear of their spacesuits, Conway saw suddenly, was there to accommodate a large, furry tail.

            "This is collision damage, dammit!" Fletcher burst out. "Losing a hypergenerator wouldn’t have done all this!"

            Conway cleared his throat. "Captain, Lieutenant Dodds, I know we haven’t time to gather material for a major research project, but if you see anything in the way of photographs, paintings, illustrations, anything that would give me information about the alien’s physiology and environment, take it along, please." He picked out another alien cadaver that was not too badly damaged, noting the pointed, fox-like head and the thick, broad-striped coat that made it look like a furry, short-legged zebra with an enormous tail. "Naydrad," he called, "here’s another one for you."

            "Yes, that must be it," the Captain said, half to himself. To Conway he added, "Doctor, these people were doubly unlucky, and the survivor doubly lucky..

            According to Fletcher, the hypergenerator failure had pulled the ship apart and sent the pieces spinning away. But in this particular place a number of the crew had survived and had managed to climb into their suits. They might even have had some warning of the approach of the second disaster-the overtaking of their section by another and equally massive piece of wreckage. When the collision occurred, the forward end of the first piece must have been swinging down while the afterpart of the second was swinging upwards. The kinetic energy of both sections had been cancelled out, bringing them both to rest and practically fusing them together. That, in the Captain’s opinion, was the only explanation for the type of injuries and damage that had occurred here, and for the fact that this was the only section of the alien ship that was not spinning.

            "I think you’re right, Captain," said Conway, fishing out of the drifting mass of debris a flat piece of plastic with what looked like a landscape on one side of it. "But surely all this is academic now."

            "Of course it is," Fletcher replied. "But I dislike unanswered questions. Doctor Prilicla, where now?"

            The little empath pointed diagonally upwards at the compartment’s ceiling. "Fifteen to twenty meters in that direction, friend Fletcher, but I must admit to some feelings of confusion. The survivor seems to be moving slowly since we entered this compartment."

            Fletcher sighed noisily. "A spacesuited and still mobile survivor," he said in relieved tones. "That will make the rescue very much easier." He looked at Dodds, and together they began cutting through the roof plating.

            "Not necessarily," said Conway. "We could have a rescue and a first-contact situation both at the same time. I much prefer new and injured e-ts to be unconscious so that first contact can be made following curative treatment and we can exercise more control over the-"

            "Doctor," the Captain broke in, "surely a star-traveling species, with the technical and philosophical background which that capability implies, would be expecting to meet what it would consider extraterrestrials. Even if they did not have the expectation, they surely would realize that there was a strong possibility of it happening."

            "Granted," said Conway, "but an e-t who is injured and only partly conscious might react instinctively, illogically, to the sight of an alien being who might physically resemble a natural enemy or a predator on its home planet. And the treatment of a conscious extraterrestrial, a stranger who has no prior knowledge of the beings carrying out the treatment, might be mistaken for something else- torture, perhaps, or medical experimentation. All too often a doctor has to be cruel to be kind."

            At that moment a large, circular section of the ceiling came free, its edges still bright red with the heat of the cutting torches, and was pushed away by Dodds and the Captain. As it followed them through the gap, Prilicla said, "I’m sorry if I confused you, friends. The survivor is moving slowly, but it is too deeply unconscious to move itself."

            Their spotlights played over a compartment that was open to space in several places, filled with drifting masses of debris, containers of various sizes, a shoal of bright objects that were probably sealed food packages, shelving and the bodies of three unsuited aliens, which were torn and swollen by the twin effects of massive external injuries and explosive decompression. The lights of the Rhabwar shone brightly through an open tangle of metal, illuminating the areas where their spotlights did not reach.

            "It’s here?" asked Fletcher in disbelief.

            "It is here," said Prilicla.

            The empath was indicating a large metal cabinet, drifting slowly past on the outer fringes of the wreckage. The container was deeply scratched and furrowed by violent contact with other metal, and there was one dent in particular that was at least six inches deep. There was a slight haze around the object, indicating that the air trapped inside was escaping slowly.

            "Naydrad!" Conway called urgently. "Forget your pressure litter. The survivor has provided one of its own, but it is depressurizing. We’ll push it outside where you can see it, then you can pull it on board with a tractor. As fast as you can, Naydrad."

            "Doctor," the Captain asked as they were maneuvering the cabinet through a gap in the wreckage, "do we spend time here looking for information on this species, or do we go on looking for other survivors?"

            "We go looking, Captain," responded Conway without hesitation. "With luck, the survivor will tell us all we want to know about its species during convalescence . .

            When the cabinet had been transferred to the Casualty Deck, the Captain examined its door actuator. He said that the operating mechanism was straightforward and that the strength of the door and its surrounding structure had kept that particular face of the cabinet from being deformed during the collision.

            "He means the door will open," Dodds translated dryly.

            Fletcher glared at the Lieutenant. "The question is, Should we open it without taking precautions-more precautions than you are taking now, Doctor?"

            Conway finished drilling, and he withdrew an air sample from the cabinet interior before replying. As he handed the sample to Murchison for analysis, he said, "Captain, the box does not contain an Earth-human DBDG with influenza. We will find an e-t of a hitherto unknown species in urgent need of medical attention, and as I have already explained, we are in no danger from extraterrestrial pathogens."

            "I keep worrying about the exception that might prove the rule, Doctor," the Captain replied doggedly. But he unsealed his visor to show everyone that he was not too badly worried.

            "Doctor Prilicla, please," came Haslam’s voice from Control. "Minus ten minutes."

            The little empath hovered briefly over the cabinet, assured them that there was no marked change in the survivor’s emotional radiation-it was still deeply unconscious, but far from being terminal-and hurried to the airlock so that when the astrogator made a close approach to the next mass of wreckage Prilicla would be able to ascertain whether or not anything had survived in it. As the Cinrusskin left, Murchison straightened up from the analyzer display.

            "If we assume that the first sample was taken from a compartment at normal atmospheric composition and pressure," she said, "then, apart from a few innocuous trace elements that our ship atmosphere does not contain, we would be quite happy breathing the same air as they do. But the sample from the cabinet is at half normal pressure and is high in carbon dioxide and water vapor. In short, the air inside that cabinet is dangerously thin and stale, and the sooner we get that beastie out of there the better."

            "Right," said Conway. He removed the sampling drill without sealing the hole it had made, and as the Casualty Deck’s air whistled into the cabinet, he said, "Open her up, Captain."

            The cabinet was lying on its back with the door fastening, a rectangular metal plate with three conical indentations on it, facing upwards. Fletcher pulled off one of his gauntlets, pressed three fingers hard into the impressions and slid the plate aside. They heard a loud click, then he lifted the door open. Inside was a confused, bloody mess.

            It took Conway several minutes to realize what had happened and to withdraw the bloodstained clothing or bedding from around the survivor. The cabinet had once contained upwards of twenty shelves, which had been pulled out hastily and the metal shelf supports padded with bedding or clothing to protect the occupant. But the collision had been a violent one, and there had been no time to attach the padding properly to the supports. As a result, both the padding and the survivor had been tumbled about the interior of the cabinet. The hapless e-t was jammed tightly into one end of the box, still bleeding sluggishly from a great many lacerations made by the shelf supports, and the colored bands of fur could barely be seen through tufted and matted patches of dried blood.

            Very gently Murchison and Naydrad helped Conway lift out the survivor and lay it on the examination table. One of the gashes in its side began to bleed more freely, but as yet they did not know enough about the being to risk using one of their coagulants. Conway began going over its body with his scanner. "There must not have been any spacesuits in that compartment. But they must have had a few minutes’ warning, enough for this one to clear and pad the cabinet and get inside, leaving the other three we saw to-"

            "No, Doctor," said the Captain. He indicated the airtight cabinet. "It cannot be closed or opened from inside. The four of them must have decided which one was to survive, and they did their best for it, very quickly and, I should say, with minimum argument. As a species they seem to be very.., civilized."

            "I see," said Conway without looking up.

            He did not know if there was any minor displacement of the survivor’s internal organs, but his scanner indicated that none of the major ones were damaged or radically out of position. The spine also appeared to be undamaged, as did the elongated rib cage. On the back just above the root of the thick, furry tail was a bright pink area, which Conway thought at first was a patch where the fur was missing. But closer examination showed that it was a natural feature, and there were large flakes of what appeared to be some kind of pigment adhering to it. The being’s head, which was tucked against its underside and partially covered by the tail, was conical, rodentlike and thickly furred. The skull itself appeared intact, but there was evidence of subcutaneous bleeding in several areas, which in a being without facial fur would have shown as massive bruising. There was some bleeding from the mouth, but Conway could not be sure whether it was due to an external blow or was the effect of lung damage caused by decompression.

            "Help me straighten the poor thing out," he said to Naydrad. "It looks as if it tried to roll itself into a ball. Probably an instinctive defense posture it adopts when threatened by natural enemies."

            "That is one of the things that puzzles me about this patient," said Murchison, looking up from her examination of one of the cadavers. "These creatures do not possess natural weapons of offense or defense as far as I can tell, or any signs of having had any in the past. Considering the fact that it is a planet’s dominant life-form that develops intelligence, I don’t see how these creatures came to dominate. Even their limbs are not built for speed, so they could not run from danger. The set used for walking are too short and are padded, while the forward set are more slender, less wellmuscled and end in four highly flexible digits that don’t possess so much as a fingernail among them. There are the fur markings, of course, but it is rare that a life-form rises to the top of its evolutionary tree by camouflage alone, or by being nice and cuddly. This is strange."

            "It sounds like it comes from a nice world," said Prilicla, who had returned briefly from its airlock duty, "for Cinrusskins."

            Conway did not join in the conversation, because he was reexamining the patient’s lungs. The slight oral bleeding had worried him, and now that the survivor was properly presented for examination there was unmistakable evidence of decompression damage in the lungs. But moving the patient into the supine position had caused some of the deeper lacerations to start bleeding again. He could do very little about the lung damage with the facilities available on the ambulance ship, but considering the weakened state of the patient, the bleeding would have to be stopped quickly.

            "Do you know enough about the composition of this beastie’s blood at present," Conway asked Murchison, "to suggest a safe coagulant and anesthetic?"

            "Coagulant, yes. Anesthetic, doubtful," Murchison replied. "I’d prefer to wait until we get back to the hospital for that. Thornnastor would be able to suggest, or synthesize, a completely safe one. Is it an emergency?"

            Before Conway could reply, Prilicla chimed in: "An anesthetic is unnecessary, friend Conway. The patient is deeply unconscious and will remain so. It is in a slowly deteriorating condition, probably caused by impaired oxygen absorption in the damaged lungs, and the loss of blood would be a contributing factor. Those cabinet-shelf supports were like blunt knives."

            "I agree," said Conway. "And if you’re trying to suggest that the patient should be hospitalized as soon as possible, I agree with that too. But this one is in no immediate danger, and I would like to be sure that there are no other survivors before we leave. However, if you continue to monitor its emotional radiation and report any sudden change in-"

            "More wreckage coming up," Haslam’s voice broke in from the wall speaker. "Doctor Prilicla to the airlock, please."

            "Yes, friend Conway," said the empath as it scuttled rapidly across the ceiling on its way to the lock.

            Before he could begin treating the survivor’s surface injuries, he had to quell a minor revolt by Naydrad, who, in common with all of its beautiful silver-furred race, had an intense aversion towards any surgical procedure that would damage or disfigure a being’s most treasured possession, its fur. To a Kelgian the removal of a strip or patch of fur, which in their species represented a means of communication equal to the spoken word, was a personal tragedy that all too often resulted in permanent psychological damage. A Kelgian’s fur did not grow again, and one whose pelt was damaged could rarely find a mate willing to accept a Kelgian who was unable to display fully its feelings. Murchison had to assure the charge nurse that the survivor’s fur was not mobile and emotion-expressive and that it would undoubtedly grow again before Naydrad was content. It did not, of course, refuse to assist Conway during the minor surgery; it simply argued, both vocally and with its rippling and twitching fur, while it was shaving and cleaning the operative field. Murchison broke in occasionally while they were suturing and

applying coagulant to the wounds crisscrossing the patient’s body, giving them odd items of information gleaned from her continuing examination and dissection of the cadavers.

            The species had two sexes, male and female, and the reproductive system seemed relatively normal. Unlike the patient, however, whose fur appeared duller and to have less color variation, the cadavers of both sexes had applied a water-soluble dye that enhanced artificially the bands of color on their body fur, which otherwise would have been of the same intensity as those of the patient. Clearly the dyes were applied for cosmetic reasons. But why the patient, who was female, had not used dye on its fur was something unclear to Murchison.

            One reason might be that the survivor was not yet fully mature and there was some cultural reason why a preadolescent of the species did not use or was forbidden to use cosmetics. Or it might be that the patient was mature and small, or of a race within the species that did not believe in painting its fur. An equally valid reason might be that the disaster had occurred before it had a chance to apply cosmetics. The only substance at all resembling cosmetic material had been the few pieces of flaking brownish pigment adhering to the patient’s bare patch above its tail, and that material had been removed during pre-op procedure. The action of its friends, or possibly its family, in placing the survivor in an airtight cabinet just before the collision led Murchison to believe that it was a young and probably preadolescent female, rather than a small mature female.

            The Federation had yet to encounter an intelligent species in which the adults would not sacrifice themselves to save their young.

            While they were busying themselves with the one living and three dead aliens, Prilicla returned from the lock from time to time to report negatively on the search for other survivors-and similarly on the one they had rescued, whose condition, according to the empath’s reading, was still deteriorating. Conway waited until Prilida had been called to the airlock once again, not wanting to inconvenience the Cinrusskin with what could well be a flood of unpleasant emotional radiation; then he called Fletcher in Control.

            "Captain, I have to make a decision and I need your advice," Conway said. "We have completed running repairs on our survivor, so far as the superficial injuries are concerned, but there is decompression damage to the lungs, which requires urgent hospitalization. As an interim measure, we have it on an enriched-oxygen-content air supply. Despite this, its condition is deteriorating, not rapidly but steadily. What, in your opinion, are the chances of picking up other survivors if we are to remain in this area for another four hours?"

            "Virtually nil, Doctor," the Captain replied.

            "I see." Conway had expected the answer to be much more complicated and hedged with probability computations and verbal qualifiers. He felt both relieved and worried.

            "You must understand, Doctor," Fletcher went on, "that the first three pieces of wreckage investigated offered the greatest possibilities of finding survivors, and since then, the likelihood of finding one has diminished sharply, as have the sizes of the collections of debris with every piece we look at. Unless you believe in miracles, Doctor, we are wasting our time here."

            "I see," said Conway.

            "If it will help you reach a decision, Doctor," the Captain went on, "I can tell you that subspace radio conditions are very good out here, and we have already made two-way contact with the survey and Cultural Contact cruiser Descartes, which I am required to do when evidence of a new intelligent species is discovered. As a matter of urgency the Descartes will investigate this wreckage with a view to obtaining all available data on the new species, and by analyzing the velocities and directions of those species, will roughly establish the alien ship’s point of departure and its destination. There are relatively few stars out here, so they should locate the home planet and star system fairly easily, because they are specialists at that job. Quite possibly, communications will be established with the aliens within a few weeks, perhaps sooner. As well, the Descartes carries two planetary landers, which in space double as close-range search and rescue vessels. They won’t have Prilicla on board, naturally, but those ships could cover the remaining wreckage much faster than we could, Doctor."

            "When will the Descartes arrive?" Conway asked.

            "Allowing for multiple Jump effects on the astrogation," said Fletcher, "four to five hours."

            Conway made no attempt to hide his relief. "Right. If there are no survivors on the next piece of wreckage, let’s head for home at once, Captain." He paused for a moment, looking at the survivor and the bodies of its friends who had not made it, then at Murchison. "If they find the home world and make contact quickly, will you ask the Descartes to request medical assistance for our friend here? Ask for a volunteer native medic to travel to Sector General to assist or, if necessary, to take charge of the treatment. In cases involving completely new life-forms we can’t afford to be proud. .

            He was also thinking that the native medic might, when it felt more at ease with the multiplicity of life-forms inhabiting the hospital, be agreeable to providing an Educator tape on its people so that the hospital staff would know exactly what they were doing if, on some future occasion, another member of its species became a patient.

            *           *           *

"Identify yourself, please. Visitor, staff or patient, and species?" came a toneless translated voice from Reception a few minutes after they had emerged into normal space. The hospital was still little more than a large blurred star against a background of smaller, brighter ones. "If you are unsure of, or are unable to give, an accurate physiological classification because of physical injury, mental confusion or ignorance of the relevant data, please make vision contact."

            Conway looked at Captain Fletcher, who drew down the corners of his mouth and raised one eyebrow in a piece of non-verbal communication which said that the person who understood the medical jargon was best fitted to answer the questions.

            "Ambulance ship Rhabwar, Senior Physician Conway speaking," he responded briskly. "Staff and one patient, all warm-blooded oxygen-breathing. Crew classifications are Earth-human DBDG, Cinrusskin GLNO and Kelgian DBLF. The patient is a DBPK, origin unknown. It has sustained injuries which will require urgent-"

            "You are expected, Rhabwar, and I have you flagged as priority traffic," the voice from Reception broke in. "Please use approach pattern Red Two and follow the red-yellow-red beacons to Lock Five-"

            "But Lock Five is a-"

            "-which is, as you know, Doctor, the principal entry port to the levels of the water-breathing AUGLs," Reception continued. "However, the accommodation being reserved for your casualty is close to Five; and Three, which you would normally use, is tied up with twenty-plus Hudlar casualties. There has been some kind of structural accident with radiation side effects during assembly of a Melfan orbiting factory, but I am aware only of the clinical details at present.

            "Thornnastor did not know what, if anything, you were bringing in," Reception added, "but it thought it better not to subject the casualty even to residual radiation. Your ETA, Doctor?"

            Conway looked at Fletcher, who said, "Two hours, sixteen minutes."

            That would be ample time for their DBPK casualty to be transferred into a pressure litter capable of maintaining the integrity of the patient’s life-support system against hard vacuum, water and a wide variety of lethal atmospheres, and for the Rhabwar’s medical team to don lightweight suits, which would enable them to accompany it. The intervening time could also be used to transmit and to consult with Diagnostician-in-Charge Thornnastor regarding their preliminary findings on the DBPK survivor and the results of Murchison’s examination of the cadavers. Thornnastor would probably request the early transfer of those cadavers so as to make a thorough investigation that would give a complete picture of the DBPK lifeform’s metabolism. Conway relayed the Captain’s estimate and asked who would be meeting the Rhabwar medics at Lock Five.

            The voice from Reception made a number of short, untranslatable noises, possibly the e-t equivalent of a stammer, then went on, "I’m sorry, Doctor. My instructions are that Rhabwar personnel are still technically in quarantine and may not enter the hospital. But you may accompany the casualty, provided you do not unseal. The assistance of your team will not be required, Doctor, but the proceedings will be broadcast on the teaching channels so that you will be able to observe and, if necessary, advise."

            "Thank you," said Conway. The sarcasm was lost, naturally, in the translation.

            "You’re welcome, Doctor," said Reception. "And now can I have your communications officer. Diagnostician Thornnastor has requested a direct link with Pathologist Murchison and yourself for purposes of consultation and preliminary diagnosis..

            A little more than two hours later, Thornnastor knew all that it was possible to know about the casualty at a distance, and the patient in its pressure litter was being transferred very gently from the Rhabwar’s boarding tube into the cavernous entry port that was Lock Five. Prilicla was also allowed to accompany the patient to monitor its emotional radiation. Reluctantly, the hospital authorities had agreed that the little Cinrusskin was unlikely to carry with it the virus that had affected the Rhabwar’s crew, and besides, it was the only medically qualified empath currently on the hospital’s staff.

            The reception and transfer team-Earth-humans in lightweight suits with the helmets, belts and boots painted bright fluorescent blue-quickly moved the pressure litter to Lock Five’s inner seal. The outer seal closed ponderously and water poured in, bubbling and steaming coldly as it entered the recently airless chamber. By the time the turbulence had cleared and Conway was able to see, the team was already manhandling the litter into the tepid green depths of the ward devoted to the treatment of the water-breathing inhabitants of Chalderescol.

            Conway was glad that their casualty was unconscious, because the Chalders, whose wide variety of ailments rarely left them immobile, swam ponderously around the litter, displaying the curiosity of all hospital patients towards anything that promised to break the monotony of ward routine.

            The ward resembled a vast undersea cavern, tastefully decorated, to Chalder eyes, with a variety of artificial native plant life, some of which was obviously carnivorous. This was not the normal environment of the natives of Chalderescol, who were highly advanced both culturally and technically, but the type of surroundings sought by healthy young Chalders going on vacation. According to Chief Psychologist O’Mara, who was rarely wrong in these matters, the primitive environment was a significant aid to recovery. But even to an Earth-human DBDG like Conway, who knew exactly what was going on, it was a spooky place.

            A completely new life-form whose language had yet to be programed into the hospital’s translation computer would not know what to think-especially if it was confronted suddenly with one of the AUGL patients.

            An adult native of Chalderescol resembled a forty-foot-long crocodile, armor-plated from the rather overlarge mouth to the tail, and with a belt of ribbon tentacles encircling its middle. Even with Prilicla present to radiate reassurance, it was much better for the patient’s peace of mind that it did not see the Chalder AUGLs, who swam to within a few meters of the litter to eye the newcomer and wish it well.

            Prilicla drifted slightly ahead of the party, a vague insect shape inside the silvery bubble of its suit, twitching occasionally to the bursts of emotional radiation in the area. Conway knew from past experience that it was not the casualty or the curious AUGL patients who were responsible for this reaction, but the feelings of the transfer team maneuvering the litter past the sleeping frames, equipment and artificial flora of the ward and the stretch of water-filled corridor beyond it. The drying and cooling units in the team’s issue lightweight suits did not operate at peak efficiency in the warm water of the AUGL level, and when strenuous physical effort was called for in that environment, the tempers shortened in direct proportion to the temperature rise.

            The Observation Ward for the new patient had been part of the Casualty Department’s initial treatment area for warm-blooded oxygen-breathers before that facility had been moved to Level 33 and extended. The intention had been to fit the original room as an additional AUGL operating theater as soon as the engineering section could get around to it, but at the present time it was still a large, square-sided bubble of air and light inside the watery vastness of the Chalder wards and service units. At the center of the room was an examination table, adjustable to the body configurations of a wide variety of physiological classifications and with provision for conversion to either an operating table or a bed. Ranged along opposing walls of the ward was the similarly non-specialized and complex equipment required for the life-support and intensive care of patients whose life processes were, at times, a partly open book.

            Although large, the room was overcrowded-mostly with people who had no business being there and no reason other than professional curiosity. Conway could see one of the scaly, membranous Illensan PVSJs, its loose protective suit transparent except for the faint yellow fog of chlorine it contained, and there was even a TLTU encased in a pressure sphere mounted on caterpillar tracks, which was the only way a being who breathed superheated steam at high pressure could associate professionally with patients and colleagues with less exotic metabolisms. The remainder were warmblooded oxygen-breathers-Melfans, Kelgians, Nidians and one Hudlar-with one thing in common besides their curiosity: the gold or gold-edged ID badges of Diagnosticians or senior physicians.

            Rarely had Conway seen so much medical talent concentrated in such a small area.

            They all stayed well clear of the transfer team as the patient was moved from the litter onto the examination table, supervised by Thornnastor itself. The litter was left unsealed and moved back to the ward entrance so as to be out of the way; then everyone began edging closer.

            Murchison and Naydrad were watching on the Rhabwar’s screen, Conway knew, as Thornnastor began the preliminary examination, which was in all respects identical to the one carried out by Murchison and Conway on the ambulance ship-a careful check of the vital signs, even though at this stage nobody could be quite sure what was or was not a normal pulse, respiration or blood pressure reading for a DBPK-followed by deep and detailed scanning and gentle probing for physical injury or deformation. While it worked, Thornnastor described in detail everything it did, saw or deduced for the many medics who were observing on the teaching channels. Occasionally it paused to ask questions of Murchison on the ambulance ship or of Conway in the ward regarding the patient’s condition immediately following its rescue, and for any comments that might be helpful.

            Thornnastor had reached its unrivaled eminence in e-t pathology by asking questions and pondering the answers, not by listening to itself pontificate.

            Finally, Thornnastor’s examination was complete. It brought its massive body fully erect so that the osseous dome housing its brain was almost hidden by the curves of its massive triple shoulders. Its four extensible eyes regarded, simultaneously, the patient, the medics ranged around the examination table and the vision pickups through which the Rhabwar and the other non-present observers were viewing the proceedings. Then it spoke.

            The most serious damage had been sustained by the patient’s lungs, where decompression effects had ruptured tissue and caused widespread bleeding. Thornnastor proposed relieving this situation by withdrawing the unwanted fluid via a minor surgical intervention through the pleural cavity and into the trachea for the purpose of assisting the patient’s breathing by positive pressure ventilation of the lungs with pure oxygen. There was a wide range of tissueregenerative medication available for warm-blooded oxygenbreathers, but the tests that would be carried out on the DBPK cadavers to find one harmless to the DBPK species would be exhaustive and would require two days at least, by which time a safe anesthetic would also be available. Without immediate surgical intervention the patient would not live for more than a few hours. Neither of the proposed procedures was lengthy, the associated pain was minimal, and as Prilicla reported, the patient was too deeply unconscious to be aware of pain, so Thornnastor, assisted by a Melfan senior physician and a Kelgian theater nurse, would operate at once.

            Considering the condition of the patient, Conway thought, it was the only sensible thing to do. He felt irked that it was not himself who was assisting Thornnastor, since he had had prior experience with the DBPK life-form. But then he realized, from listening to the respectful whispers coming from the other observers, that the Melfan senior assisting was Edanelt, one of the hospital’s top e-t surgeons, the permanent possessor of four Educator tapes, and according to the grapevine, a being shortly to be elevated to Diagnostician status. If a surgeon of Edanelt’s eminence could be big enough to assist, then Conway should be able to watch without radiating too much envy.

            It had never ceased to amaze Conway, despite the hundreds of operations he had seen Tralthans perform, that such a monstrous and physically ungainly species could produce the Federation’s finest surgeons. The DBPK patient did not know how fortunate it was, because it was said in the hospital that no life-form, no matter how hopeless its case might be, was ever lost if it came under Thornnastor’s personal care. Such a thing was unthinkable, Thornnastor was reputed to have said, because it was not in its contract..

            "Consciousness is returning," Prilicla announced suddenly, barely ten minutes after the operation was complete. "It is returning very rapidly."

            Thornnastor made a loud, untranslatable sound, which probably signified satisfaction and pleasure. "Such a rapid response to treatment promises a favorable prognosis and, I should think, an early recovery. But let us withdraw for a short distance. Even though a member of a star-traveling race is accustomed to seeing other lifeforms, in its weakened state our patient might be worried by the close proximity of a group of such large and diverse beings as ourselves. You agree, Doctor Prilicla?"

            But the little empath did not have a chance to reply, because the patient had opened its eyes and was struggling so violently against the body restraints that its tracheal air hose threatened to become detached.

            Instinctively, Thornnastor reached over the patient to steady the air hose, and the DBPK became even more agitated. The emotionsensitive Prilicla began trembling so violently that it was in danger of coming unstuck from the ceiling. Suddenly the patient stiffened and remained absolutely still for several minutes, but then it began to relax again as the Cinrusskin radiated sympathy and reassurance.

            "Thank you, Doctor Prilicla," said Thornnastor. "When communication has been established, I shall apologize to this patient for nearly frightening it to death. In the meantime, try to let it know that we wish it well."

            "Of course, friend Thornnastor. It is feeling concern now, rather than terror, and it seems to be deeply worried about something which Prilicla broke off and began to tremble violently.

            What happened next was utterly impossible.

            Thornnastor began to sway alarmingly on its six stubby legs, legs which normally gave the Tralthan species such a stable base that they frequently went to sleep standing up; then it toppled onto its side with a crash that overloaded the sound pickup on Conway’s suit. A few yards away from the treatment table the Melfan Edanelt, who had been assisting Thornnastor, collapsed slowly to the floor, its six multijointed legs becoming progressively more limp until the underside of its exoskeletal body hit the floor with a loud click. The Kelgian theater nurse had also slipped to the floor, the silvery fur on its long, cylindrical body undulating and puckering as if being affected by a tiny whirlwind. A member of the transfer team standing beside Conway dropped loosely to his hands and knees, crawled for a short distance along the floor and then rolled onto his side. Too many e-ts began speaking at once, and Earth-humans trying to outshout them, for Conway’s translator to produce anything intelligible.

            "This can’t be happening he began incredulously.

            Murchison’s voice sounded in his helmet phones, speaking on the ship frequency. "Three extraterrestrial life-forms and one Earthhuman DBDG, with four radically different metabolisms and inherent species-immunity. . . it’s quadruply impossible! As far as I see, no indications of the other unprotected life-forms being affected."

            Even when observing the impossible, Murchison remained clinical.

            "...But it is happening," Conway went on. He turned up the volume of his suit external speaker. "This is Senior Physician Conway. Instructions. All transfer team-members, seal your helmets. Team leader, sound the alarm for Contamination One. Everyone else, move away from the patient They were doing so already, Conway could see, with a degree of haste that verged on panic. "Beings already wearing protective suits stand clear, unprotected oxygen-breathers go to the pressure litter and as many as possible seal yourselves inside. Everyone else should use the breathing masks and oxygen supplies for the ward ventilators. We seem to be affected by some kind of airborne infection-"

            He broke off as the observation ward’s main screen flicked on to show the features of the irate Chief Psychologist. As O’Mara spoke Conway could hear in the background the repeated long and two short blasts on the emergency siren, which gave added urgency to the words.

            "Conway, why the blazes are you reporting lethal contamination down there? Dammit, there can’t be a lethal contamination of air and water unless the place is flooded and you’re all drowning, and I see no evidence of that!"

            "Wait," said Conway. He was kneeling by the fallen transfer team-member, his hand inside the open visor, feeling for a pulse at the temporal artery. He found it, a fast, irregular beat that he did not like at all. Then he sealed the man’s visor quickly and went on speaking to the ward: "Remember to close any breathing orifices not covered by your masks, nostrils, Melfan gills, the Kelgian speaking mouth. And you, the protected Illensan doctor, will you check Thornnastor and the Melfan Edanelt, quickly please. Prilicla, how is the original patient?"

            The chlorine-breather waddled rapidly towards the fallen Thornnastor, its transparent suit rustling. "My name is Gilvesh, Conway. But all DBDGs look the same to me, so I suppose I should not feel insulted."

            "Sorry, Gilvesh," said Conway. The chlorine-breathing Illensans were generally held to be the most visually repulsive species in the Federation as well as the most vain regarding their own physical appearance. "A snap diagnosis, please. There isn’t time for anything else. What happened to it, and what are the immediate physiological effects?"

            "Friend Conway," said Prilicla, still trembling violently, "the DBPK patient is feeling much better. It is radiating confusion and worry, but no fear and minimum physical discomfort. The condition of the other four concerns me deeply, but their emotional radiation is too faint to identify because of the high level of emotion pervading the ward."

            "I understand," said Conway, who knew that the little empath could never bring itself to criticize, however mildly, another being’s emotional shortcomings. "Attention, everyone. Apart from the four people already affected there is no immediate sign of the condition, infection, whatever it is, spreading. I would say that anyone protected by the pressure litter envelope or breathing through a mask is safe for the time being. And calm yourselves, please. We need Prilicla to help with a quick diagnosis on your colleagues, and it can’t work if the rest of you are emoting all over the place."

            While Conway was still speaking, Prilicla detached itself from the ceiling and fluttered across on its iridescent wings to the heap of silvery fur that was the Kelgian theater nurse. It withdrew its scanner and began a physical examination concurrent with its efforts to detect, isolate and identify the creature’s emotional radiation. It was no longer trembling.

            "No response to physical stimuli," Gilvesh reported from its examination of Thornnastor. "Temperature normal, breathing labored, cardiac action weak and irregular, eyes still react to light, but... This is strange, Conway. Obviously the lungs have been seriously affected, but the mechanism is unclear, and the curtailed supply of oxygen is affecting the heart and brain. I can find no signs of lung-tissue damage of the kind associated with the inhalation of corrosive or highly toxic material, nor anything to suggest that its immune system has been triggered off. There is no muscular tension or resistance; the voluntary muscles appear to be completely relaxed."

            Using his scanner without unsealing the lightweight suit, Conway had examined the team-member’s upper respiratory tract, trachea, lungs and heart with exactly similar results. But before he could say anything, Prilicla joined in: "My patient displays similar symptoms, friend Conway," it said. "Shallow and irregular respiration, cardiac condition close to fibrillation, deepening unconsciousness and all the physical and emotional signs of asphyxiation. Shall I check Edanelt?"

            "I’ll do that," said Gilvesh quickly. "Prilicla, move clear lest I walk on you. Conway, in my opinion they require intensive-care therapy as soon as possible, and a breathing assist at once."

            "I agree, friend Gilvesh," the empath said as it fluttered up to the ceiling again. "The condition of all four beings is extremely grave.

"Right," Conway agreed briskly. "Team Leader! Move your man, the DBLF and the ELNT clear and as far from the patient as possible, but close to an oxygen supply outlet. Doctor Gilvesh will supervise fitting the proper breathing masks, but keep your team-member sealed up, with his suit air supply at fifty percent oxygen. Regarding Thornnastor, you’ll need the rest of your team to move- "Or an anti-gravity sled," the Team Leader broke in. "There’s

one on the next level."

"-it even a few yards," Conway went on. "Considering its worsening condition, it would be better to rig an extension to an oxygen line and assist Thornnastor’s breathing where it is lying. And, Team Leader, do not leave the ward for a sled or anything else until we know exactly what it is that is loose in here. That goes for everyone.. . Excuse me.

            O’Mara was refusing to remain silent any longer. "So there is something loose in there, Doctor?" said the Chief Psychologist harshly. "Something much worse, seemingly, than a simple case of atmospheric contamination from an adjacent ward? Have you finally discovered the exception that proves the rule, a bug that attacks across the species’ lines?"

            "I know Earth-human pathogens cannot affect e-ts, and vice versa," Conway said impatiently, turning to the ward screen to face O’Mara. "It is supposed to be impossible, but the impossible seems to be happening, and we need help to-"

            "Friend Conway," Prilicla broke in, "Thornnastor’s condition is deteriorating steadily. I detect feelings of constriction, strangulation."

            "Doctor," the translated voice of Gilvesh joined in, "the Kelgian’s oxygen mask isn’t doing much good. The DBLF double mouth and lack of muscle control is posing problems. Positive pressure ventilation of the lungs with direct access through the trachea is indicated to avoid a complete respiratory failure."

            "Can you perform a Kelgian tracheotomy, Doctor Gilvesh?" Conway asked, turning away from the screen. He could not think of anything to do to help Thornnastor.

            "Not without a tape," Gilvesh replied.

            "No tape," said O’Mara firmly, "or anything else."

            Conway swung round to face the image of the Chief Psychologist to protest, but he already knew what O’Mara was going to say.

            "When you raised the lethal contamination alarm, Doctor," the Chief Psychologist went on grimly, "you acted instinctively, I should think, but correctly. By so doing you have probably saved the lives of thousands of beings inside the hospital. But a Contamination One alarm means that your area is isolated until the cause of the contamination has been traced and neutralized. In this case it is much more serious. There seems to be a bug loose that could decimate the hospital’s warm-blooded oxygen-breathers. For that reason your ward has been sealed off. Power, light, communication and translation facilities are available, but you are no longer connected to the main air supply system or to the automatic food distribution network, nor will you receive medical consumables of any kind. Neither will any person, mechanism or specimen for analysis be allowed out of your area. In short, Doctor Gilvesh will not be allowed to come to me for a DBLF physiology tape, nor will any Kelgian, Melfan or Tralthan doctor be allowed to volunteer to go to the aid of the affected beings. Do you understand, Doctor?"

            Conway nodded slowly.

            O’Mara’s craggy features showed a deep and uncharacteristic concern as he stared at Conway for several seconds. It was said that O’Mara’s normally abrasive and sarcastic manner was reserved only for his friends, with whom he liked to relax and be his bad-tempered self, and that he was quiet and sympathetic only when he was professionally concerned about someone.

            He has an awful lot of friends, Conway thought, and right now I’m in trouble...

            "No doubt you would like to have the life-duration figures based on the residual and tanked air remaining in the ward, and the number and species of the present occupants," the Major continued. "I’ll have them for you in a few minutes. And, Conway, try to come up with an answer..

            For several seconds Conway stared at the blank screen and told himself that there was nothing effective he could do about Thornnastor or Edanelt or the Kelgian nurse or the team-member-all of whom had suddenly switched their roles from medics to critically ill patients-without Educator tapes.

            In the normal course of events Doctor Gilvesh would have taken a DBLF tape and performed a tracheotomy on the Kelgian as a matter of course, and the Illensan senior would probably have insisted on O’Mara giving it the Tralthan tape for Thornnastor and the ELNT one for Edanelt, provided the Chief Psychologist considered Gilvesh’s mind stable enough to take three tapes for short-term use. But Gilvesh was not allowed to leave the ward even if its chlorine-breathing life depended on it, which it would very shortly.

            Conway tried not to think about the diminishing supply of air remaining in the pressure litter, where five or six e-ts were rapidly using up the tanked oxygen; or of the other beings ranged along opposing walls who were connected to breathing masks intended for patients; or of the four-hour supply carried by the transfer teammembers and himself, or of the air in the ward, which was infected and unusable, or even of the strictly limited amount of breathable chlorine carried by Gilvesh, or of the superheated atmosphere required by the TLTU. He had to think of the patients first, he told himself clinically, and try to keep them alive as long as possible. He would do this not because they were his friends and colleagues, but because they had been the first to be stricken and he had to chart the course of the infection as completely as possible so that the hospital medics of all grades and specialties would know exactly what they would have to fight.

            But the fight would have to start here in the observation ward, and there were a few things Conway could do, or try to do.

            "Gilvesh," he finally said, "go to the TLTU parked in the corner and the Hudlar on the mask beside it. I don’t know if their translators can receive me at this distance. Ask them if they will move Thornnastor to the clear area of wall beside the lock entrance. If they can do it, warn them that Tralthans must not be rolled onto their backs under normal gravity conditions, since this causes organic displacement, which would increase its respiratory difficulties, and ask one of the transfer team to hold Thorny’s mask in position while it is being moved.

            "When it is at the wall," Conway went on, "position it with its legs pointing away from the wall and ask four team members to.. ."

            While he talked Conway was thinking of all the Educator tapes he had had to digest during his career at Sector General and that, in a few cases, erasure had not been complete. None of the weird and wonderful personalities who had donated their brain recordings had remained, even in part, in his memory because that could have been psychologically dangerous. But there were odds and ends of data, pertaining chiefly to physiology and surgical procedures, which he had retained, because the Earth-human part of his mind had been particularly interested in them while the e-t personality had been in charge. The action he was considering taking with regard to the Kelgian theater nurse was dangerous-he had only the vaguest of memories regarding DBLF physiology in the respiratory tract area-and probably unprofessional. But first he had to do something for Thornnastor, even if it was little more than a firstaid measure.

            The TLTU medic, whose race existed in an environment of edible minerals and superheated steam, had a protective suit that resembled a spherical pressure boiler bristling with remote handling devices and mounted on caterpillar treads. The vehicle had not been designated to move unconscious Tralthans, but it was quite capable of doing so.

            The Hudlar doctor, classification FROB, was a blocky, pearshaped being whose home planet pulled four Earth gravities and had a high-density atmosphere so rich in suspended animal and vegetable nutrients that it resembled thick soup. Although the FROB life-form was warm-blooded and technically an oxygen-breather, it could go for long periods without air if its food supply, which it absorbed directly through its thick but highly porous tegument, was adequate. The Hudlar’s last meal had been sprayed on less than two hours earlier, Conway estimated, judging by the flaking condition of its covering of nutrient paint. It should be able to do without the oxygen mask long enough to help Thornnastor.

            ..... While they’re moving Thornnastor," Conway went on, speaking to the transfer team leader, "have your men move the pressure litter as close as possible to the Kelgian nurse. There is another Kelgian, a Diagnostician, inside the litter. Ask it if it would direct me while I try to do the tracheotomy, and make sure it has a good view of the operation through the envelope of the litter. I’ll be there in a few minutes, as soon as I check on Edanelt."

            "Edanelt’s condition is stable, friend Conway," reported Prilicla, who was keeping well clear of the Hudlar and the hissing metal juggernaut of the TLTU, who were moving Thornnastor. It made a feather-light landing on the Melfan’s carapace for a closer feel of Edanelt’s emotional radiation. "It is breathing with difficulty but is in no immediate danger."

            Of the three e-ts affected, it had been the farthest away from the DBPK casualty-which should mean something. Conway shook his head angrily. Too much was happening at once. He was not being given a chance to think..

            "Friend Conway," called Prilicla, who had moved to the DBPK casualty. "I detect feelings of increasing discomfort not associated with its injuries-feelings of constraint. It is also extremely worried, but not fearful, about something. The feeling is of intense guilt and concern. Perhaps, in addition to the injuries sustained in its ship, there is a history of psychological disturbance of the type common to certain preadolescents . .

            The mental state of the DBPK survivor was low on Conway’s order of priorities right then, and there was no way he could conceal his impatience from Prilicla.

            "May I ease its physical restraints, friend Conway?" the empath ended quickly.

            "Yes, just don’t let it loose," Conway replied, then felt stupid as soon as he finished speaking.

            The small, furry, utterly inoffensive being did not represent a physical threat-it was the pathogens it carried that provided the danger, and they were already loose. But when Prilicla’s fragile pipestem manipulators touched the buttons that reduced the tightness of the restraining webbing holding the DBPK to the examination table, it did not try to escape. Instead it moved itself carefully until it lay like a sleeping Earth cat, curled up with its head pushed underneath its long and furry tail, looking like a mound of striped fur except for the bare patch at the root of its tail where the skin showed pinkish brown.

            "It feels much more comfortable now, but is still worried, friend Conway," the Cinrusskin reported. Then it scuttled across the ceiling towards Thornnastor’s position, trembling slightly because the unconscious Diagnostician was experiencing strong emotions.

            The TLTU had taped Thornnastor’s rear legs together, then withdrawn to enable the Hudlar and four team-members to do their work. With one man each grasping a middle or forward leg, they strained to pull them diagonally apart so as to expand the Tralthan’s chest as much as possible. The Hudlar was saying, "Pull together. Harder. Hold it. Let go." When it said "let go" the legs resumed their natural position while simultaneously the Hudlar pressed on Thornnastor’s massive rib-cage with its own not inconsiderable weight to ensure that the lungs were deflated before the process was repeated. Behind the visors of the men tugging on Thornnastor’s legs were faces deep red and shining with perspiration, and some of the things they were saying were not suitable for translation.

            Every medic, orderly and maintenance man in Sector General was taught the rudiments of first aid as it applied to members of the species that made up the Galactic Federation-those, that is, whose environmental requirements were not so exotic that only another member of their race could aid them without delay. The instructions for giving artificial respiration to a Tralthan FGLI was to tie the rear legs together and open and close the other four so as to suck air into the FGLI’s lungs. Thornnastor’s mask was in position, and it was being forced to breathe pure oxygen. Prilicla was available to report any change in its condition.

            But a Kelgian tracheotomy was most decidedly not a first-aid measure. Except for a thin-walled, narrow casing that housed the brain, the DBLF species had no bone structure. The DBLF body was composed of an outer cylinder of musculature, which, in addition to being its primary means of locomotion, protected the vital organs within it. The Kelgian life-form was dangerously susceptible to lethal injury, because the complex and highly vulnerable circulatory system that fed those great bands of encircling muscle ran close under the skin and was protected only by its thick fur. An injury that most other species would consider superficial could cause a Kelgian to bleed to death in minutes. Conway’s problem was that the Kelgian trachea was deeply buried under the neck muscles and passed within half an inch of the main artery and vein, which carried the blood supply to and from the brain.

            With an Earth-human surgeon operating to the verbal instructions of another Kelgian, and hampered by the lack of a DBLF physiology tape and suit gauntlets, the procedure promised to be both difficult and dangerous.

            "I would prefer," the Kelgian Diagnostician announced, its face pressed against the transparent wall of the pressure litter, "to perform this operation myself, Doctor."

            Conway did not reply, because they both knew that if the Diagnostician left the litter it would be open to the air of the ward and whatever form of infection it contained, as would the other occupants of the litter. Instead, he began removing a narrow patch of fur from the Kelgian nurse’s neck while Gilvesh sterilized the area.

            "Try not to shave off too much fur, Doctor," said the Kelgian Diagnostician, who had given its name as Towan. "It will not grow again on an adult and the condition of its fur is of great psychological importance to a Kelgian, particularly in premating approaches to the opposite sex."

            "I know that," said Conway.

            As he worked Conway found that some of the memories he retained from the Kelgian physiology tapes were trustworthy, while many others were not. He was very glad of the voice from the litter, which kept him from going disastrously wrong. During the fifteen minutes it took to perform the operation, Towan fumed and fretted and poured out a constant stream of instruction, advice and warnings, which at times were indistinguishable from personal insults- the fellow-feeling among Kelgians was very strong. Then, finally, the operation and the abuse ended, and Gilvesh began preparing to connect the nurse to a ventilator while Conway walked across the ward to have a closer look at Thornnastor.

            Suddenly the ward screen lit again, this time to show the faces of O’Mara and the Monitor Corps officer in charge of hospital supply and maintenance, Colonel Skempton. It was the Colonel who finally spoke.

            "We have been calculating the time left to you using the air supply currently available in your ward, Doctor," he said quietly. "The people on breathing masks, provided the bug doesn’t get to them through one of their other body orifices or they don’t fall asleep and dislodge the masks, have about three days’ supply of air. The reason for this is that the six ventilator systems in that ward each carry a ten-hour supply of oxygen as well as other gases which are of no interest to you in the current situation-nitrogen, CO2 and the like. The transfer team-members each have a four-hour supply in their lightweight suits, providing they conserve their oxygen by resting as much as possible-"

            The Colonel broke off, and Conway knew that he was staring at the four team-members who were helping the Hudlar give artificial respiration to Thornnastor; then he cleared his throat and went on: "The Kelgian, Nidian and three Earth-humans sheltering inside the litter have less than an hour’s supply remaining. However, it is possible for the team-members to recharge the litter and their own suits with air from the ventilator supply as this becomes necessary. If this is done and everyone rests as much as possible, those of you who do not succumb to the bug should still be alive in, say, thirty hours, which gives us time to-"

            "What about Gilvesh and the TLTU?" said Conway sharply.

            "Recharging the TLTU’s life-support system is a specialist’s job," Colonel Skempton replied, "and any unqualified tinkering could result in a steam explosion down there to add to your other difficulties. As for Doctor Gilvesh, you will remember that that is an observation ward for warm-blooded oxygen-breathers. There is no chlorine available. I’m sorry.

            Quietly but firmly, Conway said, "We need supplies of tanked oxygen and chlorine, a nutrient paint sprayer for the Hudlar, a recharging unit for the TLTU’s vehicle, and low-residue rations complete with feeding tubes, which will enable the food to be taken without it being exposed to the air of the ward. With the exception of the TLTU’s recharger-and I’m sure the team leader would be capable of handling that job if he had step-by-step instructions from one of the maintenance engineers-these items are not bulky. You could move them through the AUGL section and into our lock chamber with probably less trouble than it took getting the DBPK casualty here."

            Skempton shook his head. Just as quietly and firmly he said, "We considered that method of supplying you, Doctor. But we noticed that your lock chamber was left open after the casualty was taken in, and as a result the chamber has been open to contamination for the same period as the rest of the ward. If the lock was cycled to enable us to load it with the needed supplies, water would be drawn in from the AUGL section. When your people pumped out the water to retrieve those supplies, that water, infected with whatever it is that is loose in there, would be returned to the AUGL section, with results we cannot even guess at. I have been told by a number of your colleagues, Doctor, that airborne bacteria can frequently survive and propagate in water.