Burton did not autopsy the anticoagulated rats.

  Instead, he turned his attention to the original autopsy specimens, the first black Norway rat and the first rhesus monkey to be exposed to the capsule. He performed a complete autopsy on these animals, but discarded the anticoagulated animals.

  It would be forty-eight hours before he realized his error.

  The autopsies he performed were careful and good; he did them slowly, reminding himself that he must overlook nothing. He removed the internal organs from the rat and monkey and examined each, removing samples for both the light and electron microscopes.

  To gross inspection, the animals had died of total, intravascular coagulation. The arteries, the heart, lungs, kidneys, liver and spleen-- all the blood-containing organs-- were rock-hard, solid. This was what he had expected.

  He carried his tissue slices across the room to prepare frozen sections for microscopic examination. As each section was completed by his technician, he slipped it under the microscope, examined it, and photographed it.

  The tissues were normal. Except for the clotted blood, there was nothing unusual about them at all. He knew that these same pieces of tissue would now be sent to the microscopy lab, where another technician would prepare stained sections, using hematoxylin-eosin, periodic acid-Schiff, and Zenker-formalin stains. Sections of nerve would be stained with Nissl and Cajal gold preparations. This process would take an additional twelve to fifteen hours. He could hope, of course, that the stained sections would reveal something more, but he had no reason to believe they would.

  Similarly, he was unenthusiastic about the prospects for electron microscopy. The electron microscope was a valuable tool, but occasionally it made things more difficult, not easier. The electron microscope could provide great magnification and clear detail-but only if you knew where to look. It was excellent for examining a single cell, or part of a cell. But first you had to know which cell to examine. And there were billions of cells in a human body.

  At the end of ten hours of work, he sat back to consider what he had learned. He drew up a short list:

  1. The lethal agent is approximately 1 micron in size. Therefore it is not a gas or molecule, or even a large protein or virus. It is the size of a cell, and may actually be a cell of some sort.

  2. The lethal agent is transmitted by air. Dead organisms are not infectious.

  3. The lethal agent is inspired by the victim, entering the lungs. There it presumably crosses over into the bloodstream and starts coagulation.

  4. The lethal agent causes death through coagulation. This occurs within seconds, and coincides with total coagulation of the entire body vascular system.

  5. Anticoagulant drugs do not prevent this process.

  6. No other pathologic abnormalities are known to occur in the dying animal.

  Burton looked at his list and shook his head. Anticoagulants might not work, but the fact was that something s the process. There was a way that it could be done. He knew that.

  Because two people had survived.

  17. Recovery

  AT 1147 HOURS, MARK HALL WAS BENT OVER THE computer, staring at the console that showed the laboratory results from Peter Jackson and the infant. The computer was giving results as they were finished by the automated laboratory equipment; by now, nearly all results were in.

  The infant, Hall observed, was normal. The computer did not mince words:

  SUBJECT CODED-- INFANT-- SHOWS ALL LABORATORY VALUES WITHIN NORMAL LIMITS

  However, Peter Jackson was another problem entirely. His results were abnormal in several respects.

  SUBJECT CODED JACKSON, PETER

  LABORATORY VALUES NOT WITHIN NORMAL LIMITS FOLLOW

  TEST : NORMAL : VALUE

  HEMATOC : 38-54 : 21 INITIAL

  25 REPEAT

  29 REPEAT

  33 REPEAT

  37 REPEAT

  BUN : 10-20 : 50

  COUNTS RETIC : 1 : 6

  BLOOD SMEAR SHOWS MANY IMMATURE ERYTHROCYTE FORMS

  TEST : NORMAL : VALUE

  PRO TIME : L2 : 12

  BLOOD PH : 7.40 : 7.31

  SGOT : 40 : 75

  SED RATE : 9 : 29

  AMYLASE : 70-200 : 450

  Some of the results were easy to understand, others were not. The hematocrit, for example, was rising because Jackson was receiving transfusions of whole blood and packed red cells. The BUN, or blood urea nitrogen, was a test of kidney function and was mildly elevated, probably because of decreased blood flow.

  Other analyses were consistent with blood loss. The reticulocyte count was up from 1 to 6 per cent.  Jackson had been anemic for some time. He showed immature red-cell forms, which meant that his body was struggling to replace lost blood, and so had to put young, immature red cells into circulation.

  The prothrombin time indicated that while Jackson was bleeding from somewhere in his gastrointestinal tract, he had no primary bleeding problem: his blood clotted normally.

  The sedimentation rate and SGOT were indices of tissue destruction. Somewhere in Jackson's body, tissues were dying off.

  But the pH of the blood was a bit of a puzzle. At 7.31, it was too acid, though not strikingly so. Hall was at a loss to explain this. So was the computer.

  SUBJECT CODED JACKSON, PETER

  DIAGNOSTIC PROBABILITIES

  1. ACUTE AND CHRONIC BLOOD LOSS ETIOLOGY GASTROINTESTINAL .884 NO OTHER STATISTICALLY SIGNIFICANT SOURCES.

  2. ACIDOSIS ETIOLOGY UNEXPLAINED FURTHER DATA REQUIRED SUGGEST HISTORY

  Hall read the printout and shrugged. The computer might suggest he talk to the patient, but that was easier said than done. Jackson was comatose, and if he had ingested anything to make his blood acid, they would not find out until he revived.

  On the other hand, perhaps he could test blood gases. He turned to the computer and punched in a request for blood gases.

  The computer responded stubbornly.

  PATIENT HISTORY PREFERABLE TO LABORATORY ANALYSES

  Hall typed in: "Patient comatose."

  The computer seemed to consider this, and then flashed back:

  PATIENT MONITORS NOT COMPATIBLE WITH COMA -- EEG SHOWS ALPHA WAVES DIAGNOSTIC OF SLEEP

  "I'll be damned," Hall said. He looked through the window and saw that Jackson was, indeed, stirring sleepily. He crawled down through the tunnel to his plastic suit and leaned over the patient.

  "Mr. Jackson, wake up..."

  Slowly, he opened his eyes and stared at Hall. He blinked, not believing.

  "Don't be frightened," Hall said quietly. "You're sick, and we have been taking care of you. Do you feel better?"

  Jackson swallowed, and nodded. He seemed afraid to speak. But the pallor of his skin was gone; his cheeks had a slight pinkish tinge; his fingernails were no longer gray.

  "How do you feel now?"

  "Okay... Who are you?

  "I am Dr. Hall. I have been taking care of you. You were bleeding very badly. We had to give you a transfusion."

  He nodded, accepting this quite calmly. Somehow, his manner rung a bell for Hall, who said, "Has this happened to you before?"

  "Yes," he said. "Twice."

  "How did it happen before?"

  "I don't know where I am," he said, looking around the room. "Is this a hospital? Why are you wearing that thing?"

  "No, this isn't a hospital. It is a special laboratory in Nevada."

  "Nevada?" He closed his eyes and shook his head. "But I'm in Arizona..."

  "Not now. We brought you here, so we could help you."

  "How come that suit?"

  "We brought you from Piedmont. There was a disease in Piedmont. You are now in an isolation chamber."

  "You mean I'm contagious?"

  "Well, we don't know for sure. But we must--"

  "Listen," he said, suddenly trying to get up, "this place gives me the creeps. I'm getting out of here. I don't like it here."

  He struggled in the bed, trying to move against the straps. Hall pushed him back gently.

  "Just relax, Mr. Jackson. Everything will be all right, but you must relax. You've been a sick man."

  Slowly, Jackson lay back. Then: "I want a cigarette."

  "I'm afraid you can't have one."

  "What the hell, I want one."

  "I'm sorry, smoking is not allowed."

  "Look here, young fella, when you've lived as long as I have you'll know what you can do and what you can't do. They told me before. None of that Mexican food, no liquor, no butts. I tried it for a spell. You know how that makes a body feel? Terrible, just terrible."

  "Who told you?"

  "The doctors."

  "What doctors?"

  "Those doctors in Phoenix. Big fancy hospital, all that shiny equipment and all those shiny white uniforms. Real fancy hospital. I wouldn't have gone there, except for my sister. She insisted. She lives in Phoenix, you know, with that husband of hers, George. Stupid ninny. I didn't want no fancy hospital, I just wanted to rest up, is all. But she insisted, so I went."

  "When was this?"

  "Last year. June it was, or July."

  "Why did you go to the hospital?"

  "Why does anybody go to the hospital? I was sick, dammit."

  "What was your problem?"

  "This damn stomach of mine, same as always."

  "Bleeding?"

  "Hell, bleeding. Every time I hiccoughed I came up with blood. Never knew a body had so much blood in it."

  "Bleeding in your stomach?"

  "Yeah. Like I said, I had it before. All these needles stuck in you--" he nodded to the intravenous lines-- "and all the blood going into you. Phoenix last year, and then Tucson the year before that. Now, Tucson was a right nice place. Right nice. Had me a pretty little nurse and all." Abruptly, he closed his mouth. "How old are you, son, anyhow? You don't seem old enough to be a doctor.

  "I'm a surgeon," Hall said.

  "Surgeon! Oh no you don't. They kept trying to get me to do it, and I kept saying, Not on your sweet life. No indeedy. Not taking it out of me."

  "You've had an ulcer for two years?"

  "A bit more. The pains started out of the clear blue. Thought I had a touch of indigestion, you know, until the bleeding started up."

  A two-year history, Hall thought. Definitely ulcer, not cancer.

  "And you went to the hospital?"

  "Yep. Fixed me up fine. Warned me off spicy foods and hard stuff and cigarettes. And I tried, sonny, I sure did. But it wasn't no good. A man gets used to his pleasures.

  "So in a year, you were back in the hospital."

  "Yeah. Big old place in Phoenix, with that stupid ninny George and my sister visiting me every day. He's a book-learning fool, you know. Lawyer. Talks real big, but he hasn't got the sense God gave a grasshopper's behind."

  "And they wanted to operate in Phoenix?"

  "Sure they did. No offense, sonny, but any doctor'll operate on you, give him half a chance. It's the way they think. I just told them I'd gone this far with my old stomach, and I reckoned Id finish the stretch with it."

  "When did you leave the hospital?"

  "Must have been early August sometime. First week, or thereabouts."

  "And when did you start smoking and drinking and eating the wrong foods?"

  "Now don't lecture me, sonny," Jackson said. "I'v6 been living for sixty-nine years, eating all the wrong foods and doing all the wrong things. I like it that way, and if I can't keep it up, well then the hell with it."

  "But you must have had pain," Hall said, frowning.

  "Oh, sure, it kicked up some. Specially if I didn't eat. But I found a way to fix that.

  "Yes?"

  "Sure. They gave me this milk stuff at the hospital, and wanted me to keep on with it. Hundred times a day, in little sips. Milk stuff. Tasted like chalk. But I found a better thing."

  "What was that?"

  "Aspirin," Jackson said.

  "Aspirin?"

  "Sure. Works real nice."

  "How much aspirin did you take?"

  "Fair bit, toward the end. I was doing a bottle a day. You know them bottles it comes in?"

  Hall nodded. No wonder the man was acid. Aspirin was acetylsalicylic acid, and if it was taken in sufficient quantities, it would acidify you. Aspirin was a gastric irritant, and it could exacerbate bleeding.

  "Didn't anybody tell you aspirin would make the bleeding worse?" he asked.

  "Sure," Jackson said. "They told me. But I didn't mind none. Because it stopped the pains, see. That, plus a little squeeze."

  "Squeeze?"

  "Red-eye. You know."

  Hall shook his head. He didn't know.

  "Sterno. Pink lady. You take it, see, and put it in cloth, and squeeze it out..."

  Hall sighed. "You were drinking Sterno," he said.

  "Well, only when I couldn't get nothing else. Aspirin and squeeze, see, really kills that pain."

  "Sterno isn't only alcohol. It's methanol, too."

  "Doesn't hurt you, does it?" Jackson asked, in a voice suddenly concerned.

  "As a matter of fact, it does. It can make you go blind, and it can even kill you."

  "Well, hell, it made me feel better, so I took it," Jackson said.

  "Did this aspirin and squeeze have any effect on you? On your breathing?"

  "Well, now you mention it, I was a tad short of breath. But what the hell, I don't need much breath at my age."

  Jackson yawned and closed his eyes.

  "You're awful full of questions, boy. I want to sleep now."

  Hall looked at him, and decided the man was right. It would be best to proceed slowly, at least for a time. He crawled back down the tunnel and out to the main room. He turned to his assistant:

  "Our friend Mr. Jackson has a two-year history of ulcer. We'd better keep the blood going in for another couple of units, then we can stop and see what's happening. Drop an NG tube and start icewater lavage."

  A gong rang, echoing softly through the room.

  "What's that?"

  "The twelve-hour mark. It means we have to change our clothing. And it means you have a conference."

  "I do? Where?"

  "The CR off the dining room."

  Hall nodded, and left.

  ***

  In delta sector, the computers hummed and clicked softly, as Captain Arthur Morris punched through a new program on the console. Captain Morris was a programmer; he had been sent to delta sector by the command on Level I because no MCN messages had been received for nine hours. It was possible, of course, that there had been no priority transmissions; but it was also unlikely.

  And if there had been unreceived MCN messages, then the computers were not functioning properly. Captain Morris watched as the computer ran its usual internal check program, which read out as all circuits functioning.

  Unsatisfied, he punched in the CHECKLIM program, a more rigorous testing of the circuit banks. It required 0.03 seconds for the machine to come back with its answer: a row of five green lights blinked on the console. He walked over to the teleprinter and watched as it typed: