In Michaels' office, Grant found himself looking at the map of the circulatory system open-mouthed.

Michaels said, "It's an unholy mess, but it's a map of the territory. Every mark on it is a road; every junction is a cross-road: That map is as intricate as a road-map of the United States. More so, for it's in three dimensions."

"Good Lord!"

"A hundred thousand miles of blood vessels. You see very little of it now; most of it is microscopic and won't be visible to you without considerable magnification, but put it all together in a single line and it would go four times around the Earth or, if you prefer, nearly half-way to the Moon. -Have you had any sleep, Grant?"

"About six hours. I napped on the plane, too. I'm in good shape."

"Good, you'll have a chance to eat and shave and tend to other such matters if necessary. I wish I had slept." He held up a hand as soon as he had said that. "Not that I'm in bad shape. I'm not complaining. Have you ever taken a morphogen?"

"Never heard of it. Is it some kind of drug?"

"Yes. Relatively new. It's not the sleep you need, you know. One doesn't rest in sleep to any greater extent than one would by stretching out comfortably with the eyes open. Less, maybe. It's the dreams we need. We've got to have dreaming time, otherwise cerebral coordination breaks down and you begin to have hallucinations and, eventually, death."

"The morphogen makes you dream? Is that it?"

"Exactly. It knocks you out for half an hour of solid dreaming and then you're set for the day. Take my advice, though, and stay away from the stuff unless it's an emergency."

"Why? Does it leave you tired?"

"No. Not particularly tired. It's just that the dreams are bad. The morphogen vacuums the mind; cleans out the mental garbage-pit accumulated during the day; and it's quite an experience. Don't do it. -But, I had no choice. That map had to be prepared and I spent all night at it."

"That map?"

"It's Benes' system to the last capillary and I've had to learn all I could concerning it. Up here, almost centrally located in the cranium, right near the pituitary, is the blood clot."

"Is that the problem?"

"It certainly is. Everything else can be handled. The general bruises and contusions, the shock, the concussion. The clot can't be, not without surgery. And quickly."

"How long has he got, Dr. Michaels?"

"Can't say. It won't be fatal, we hope, for quite a while, but brain damage will come long before death does. And for this organization, brain damage will be as bad as death. The people here expect miracles from our Benes and now they've been badly rattled. Carter, in particular, has had a bad blow and wants you."

Grant said, "You mean he expects the Other Side will try again."

"He doesn't say so, but I suspect that's what he fears and why he wants you on the team."

Grant looked about. "Is there any reason to think this place has been penetrated. Have they planted agents here?"

"Not to my knowledge, but Carter is a suspicious man. I think he suspects the possibility of medical assassination."

"Duval?"

Michaels shrugged. "He's an unpopular character and the Instrument he uses can cause death if it slips a hairbreadth."

"How can he be stopped?"

"He can't."

"Then use someone else; someone you can trust."

"No one else has the necessary skill. And Duval is right here with us. And, after all, there is no proof that he isn't completely loyal."

"But if I'm placed near Duval as a male nurse and if I tint assigned the task of watching him closely, I will do no good. I won't know what he's doing; or whether he's doing it honestly and correctly. In fact, I tell you that when he opens the skull, I'll probably pass out."

"He won't open the skull," said Michaels. "The clot can't be reached from outside. He's definite about that."

"But, then ..."

"We'll reach it from the inside."

Grant frowned. Slowly, he shook his head. "You know. I don't know what you're talking about."

Michaels said, quietly, "Mr. Grant, everyone else engaged in this project knows the score, and understands exactly what he or she is to do. You're the outsider and it is rather a chore to have to educate you. Still, if I must, I must. I'm going to have to acquaint you with some of the theoretical work done in this institution."

Grant's lip quirked. "Sorry, doctor, but you've just said a naughty word. At college, I majored in football with a strong minor in girls. Don't waste theory on me."

"I have seen your record, Mr. Grant, and it is not quite as you say. However, I will not deprive you of your manhood by accusing you of your obvious intelligence and education, even if we are in private. I will not waste theory on you, but will get the nub of the information to you without that. -I assume you have observed our insigne, CMDF.

"Sure have."

"Do you have any idea of what it means?"

"I've made a few guesses. How about Consolidated Martian Dimwits and Fools. I've got a better one than that but it's unprintable."

"It happens to stand for Combined Miniature Deterrent Forces."

"That makes less sense than my suggestion," said Grant. "I'll explain. Have you ever heard of the miniaturization controversy?"

Grant thought a while. "I was in college then. We spent a couple of sessions on it in the physics course." "In between football games?"

"Yes. In the off-season, as a matter of fact. If I remember it, a group of physicists claimed they could reduce the size of objects to any degree, and it was exposed as a fraud. Well, maybe not a fraud but a mistake anyway. I remember the class ran through several arguments showing why it was impossible to reduce a man to the size of, say, a mouse, and keep him a man."

"I'm sure this was done in every college in the land. Do you remember any of the objections?"

"I think so. If you're going to reduce size you can do it in one of two ways. You can push the individual atoms of an object closer together; or you can discard a certain proportion of the atoms altogether. To push the atoms together against the inter-atomic repulsive forces would take extraordinary pressures. The pressures at the center of Jupiter would be insufficient to compress a man to the size of a mouse. Am I right so far?"

"You are luminous as the day."

"And even if you managed it, the pressure would kill anything alive. Aside from that, an object reduced in size by pushing atoms together would retain all its original mass, and an object the size of a mouse with the mass of a man would be difficult to handle."

"Amazing, Mr. Grant. You must have amused your girlfriends for many hours with this romantic talk. And the other method?"

"The other method is to remove atoms in careful ratio so that the mass and size of an object decreases while the relationship of the parts remains constant. Only if you reduce a man to the size of a mouse you can keep only one atom out of maybe seventy thousand. If you do that to the brain, what is left is scarcely more complicated than the brain of a mouse in the first place. Besides, how do you re-expand the object, as the miniaturizing physicists claimed to be able to do? How do you get the atoms back and put them in their right places?"

"Quite so, Mr. Grant. But then how did some reputable physicists come to think that miniaturization was practical?"

"I don't know, doctor, but you don't hear of it any more."

"Partly because the colleges did such a careful job-under orders-of knocking it on the head. The technique went underground both here and on the Other Side. Literally. Here. Underground." It was almost with passion that Michaels tapped the desk before him. "And we must maintain special courses in miniaturization techniques for graduate physicists who can learn it nowhere else-except in analogous schools on the Other Side. Miniaturization is quite possible, but by neither method you have described. Have you ever seen a photograph enlarged, Mr. Grant? Or reduced to microfilm size?"

"Of course."

"Without theory, then, I tell you that the same process can be used on three-dimensional objects; even on a man. We are miniaturized, not as literal objects, but as images; as three-dimensional images manipulated from outside the universe of space-time."

Grant smiled. "Now, teacher, those are just words."

"Yes, but you don't want theory, do you? What physicists discovered ten years ago was the utilization of hyper-space; a space, that is, of more than the three ordinary spatial dimensions. The concept is beyond grasping; the mathematics are almost beyond grasp; but the funny part is that it can be done. Objects can be miniaturized. We nether get rid of atoms nor push them together. We reduce the size of the atoms, too; we reduce everything; and the mass decreases automatically. When we wish, we restore the size."

"You sound serious," said Grant. "Are you telling me that we can really reduce a man to the size of a mouse?"

"In principle we can reduce a man to the size of a bacterium, of a virus, of an atom. There is no theoretical limit to the amount of miniaturization. We can shrink an army with all its men and equipment to a size that will fit in a match-box. Ideally, we could then ship that match-box where it is needed and put the army into business after restoring it to full size. You see the significance?"

Grant said, "And the Other Side can do it, too, I take it?"

"We're certain they can. -But come, Grant, matters are progressing at full speed and our time is limited. Come with me."

It was "come with me" here and "come with me" there. Since Grant had awakened that morning, he had not been allowed to remain in one place for longer than fifteen minutes. It annoyed him and yet there seemed nothing he could do about it. Was it a deliberate attempt to keep him from having time enough to think? What were they preparing to spring on him?

He and Michaels were in the scooter now, Michaels handling it like a veteran.

"If both We and They have it, we neutralize each other," said Grant.

"Yes, but in addition," said Michaels, "it does neither of us very much good. There's a catch."

"Oh?"

"We've worked for ten years to extend the size ratio; to reach greater intensities of miniaturization, and of expansion, too-just a matter of reversing the hyper-field. Unfortunately, we've reached our theoretical limits in this direction."

"What are they?"

"Not very favorable. The Uncertainty Principle intervenes. Extent of miniaturization multiplied by the duration of miniaturization, using the proper units, of course, is equal to an expression containing Planck's constant. If a man is reduced to half-size, he can be kept so for centuries. If he is reduced to mouse-size, that can be kept up for days. If he is reduced to bacterium-size, that can be kept up only for hours. After that he expands again."

"But then he can be miniaturized again.",

"Only after a sizable lag period. Do you want some of the mathematical background?"

"No. I'll take your word for everything."

They had arrived at the foot of an escalator. Michaels got out of the scooter with a small, weary grunt. Grant vaulted the side.

He leaned against the railing as the staircase moved majestically upward. "And what has Benes got?"

"They tell me he claims he can beat the Uncertainty Principle. Supposedly, he knows how to maintain miniaturization indefinitely."

"You don't sound as though you believe that."

Michaels shrugged, "I am skeptical. If he extends both miniaturization intensity and 'miniaturization duration that can only be at the expense of something else, but for the life of me I can't imagine what that something else might be. Perhaps that only means I am not a Benes. In any case, he says he can do it and we cannot take the chance of not believing him. Neither can the Other - er - Side, so they've tried to kill him."

They had come to the top of the escalator and Michaels had paused there briefly to complete his remark. Now he moved back to take a second escalator up another floor.

"Now, Grant, you can understand what we must do - save Benes. Why we must do it-for the information he has. And how we must do it-by miniaturization."

"Why by miniaturization?"

"Because the brain clot cannot be reached from outside. I told you that. So we will miniaturize a submarine, inject it into an artery, and with Captain Owens at the controls and with myself as pilot, journey to the clot. There, Duval and his assistant, Miss Peterson, will operate."

Grant's eyes opened wide. "And I?"

"You will be along as a member of the crew. General supervision, apparently."

Grant said, violently, "Not I. I am not volunteering for any such thing. Not for a minute."

He turned and started walking down the up-escalator, with little effect.

Michaels followed him, sounding amused. "It is your business to take risks, isn't it?"

"Risks of my own choosing. Risks I am used to. Risks I am prepared for. Give me as much time to think of miniaturization as you have had and I'll take the risk."

"My dear Grant. You have not been asked to volunteer. It is my understanding that you have been assigned to this duty. And now its importance has been explained to you. After all, I am going to, and I am not as young as you, nor have I ever been a football player. In fact, I'll tell you. I was depending on you to keep my courage up by coming along, since courage is your business."

"If so, I'm a rotten business man," muttered Grant. Irrelevantly, almost petulantly, he said, "I want coffee."

He stood still and let the escalator carry him up again. Near the top of the escalator was a door marked "Conference Room." They entered.

Grant grew aware of the contents of the room in stages. What he saw first was that one end of the long table that filled the center of the room was a. multi-cup coffee dispenser and that next to it was a tray of sandwiches.

He moved toward that at once and it was only after downing half a cup of it hot and black and following that by a Grant-sized bite of a sandwich, that item two entered his awareness.

This was Duval's assistant - Miss Peterson, wasn't that her name? - looking down in the mouth but very beautiful and standing terribly close to Duval. Grant had the instant feeling that he was going to find it difficult to like the surgeon and only then did he begin to absorb the rest of the room.

A colonel sat at one end of the table, looking annoyed. One hand twirled an ashtray slowly while the ashes of his cigarette dropped to the floor. He said emphatically to Duval, "I've made my attitude quite clear."

Grant recognized Captain Owens standing under the portrait of the president. The eagerness and smiles he had seen at the airport were gone and there was a bruise on one cheekbone. He looked nervous and upset and Grant sympathized with the sensation.

"Who's the colonel?" Grant asked Michaels in a low voice.

"Donald Reid, my opposite number on the military side of the fence."

"I take it he's annoyed with Duval."

"Constantly. He's got a lot of company. Few like him."

Grant had the impulse to answer, She seems to, but the words sounded petty in his thoughts and he dismissed them. Lord, what a dish! What did she see in that solemn cutthroat?

Reid was talking in a low voice, carefully controlled. "And aside from that, doctor, what is she doing here?"

"Miss Cora Peterson," said Duval; icily, "is my assistant. Where I go professionally, she accompanies me professionally.,

"This is a dangerous mission ..."

"And Miss Peterson has volunteered, understanding full well its dangers."

"A number of men, entirely qualified to help, have also volunteered. Matters would be far less complicated if one of those men accompanied you. I will assign you one."

"You will not assign me one, colonel, for if you do, I will not go, and there will be no power to make me. Miss Peterson is a third and fourth arm to me. She knows my requirements well enough to do her job without instructions, to be there before I call, to supply what is needed without being asked. I will not take a stranger who will need to be shouted at. I can not be responsible for success if I lose one second because my technician and I do not mesh, and I will not take any assignment in which I am not given a free hand with which to arrange matters in such a way as will carry with it the best chance for success."

Grant's eye moved to Cora Peterson again. She looked acutely embarrassed, yet stared at Duval with the expression Grant had once seen in a beagle's eye when its little boy owner returned from school. Grant found that intensely annoying.

Michaels' voice cut across the argument as Reid was rising furiously to his feet. "I would suggest, Don, that since the key step of the entire operation rests upon Dr. Duval's hand and eye and since, in fact, we cannot now dictate to him, we humor him in this respect-without prejudice to necessary action afterward, eh? I am willing to take responsibility for that."

He was offering Reid a face-saving way out, Grant realized, and Reid, fuming darkly, would have to take it.

Reid slammed the flat of his hand on the table before him. "All right. Let it be on record that I opposed this." He sat back, lips trembling.

Duval sat down also, unconcerned. Grant moved forward to pull out a chair for Cora, but she helped herself and was seated before he could reach her.

Michaels said, "Dr. Duval, this is Grant, a young man who will be accompanying us."

"As muscle man, doctor," said Grant. "My only qualification."

Duval looked up cursorily. His acknowledgement was a minimal nod thrown in Grant's general direction. "And Miss Peterson."

Grant smiled flashily. She smiled not at all and said, "How do you do?"

"Hello," said Grant, looked down at what little was left of his second sandwich, realized that no one else was eating at all, and put it down.

Carter came in at this point, walking rapidly and nodding vaguely to right and left. He sat down and said, "Will you join us, Captain Owens? Grant?"

Owens reluctantly moved to the table and took his place opposite Duval. Grant sat down several chairs removed and found himself able, in looking at Carter, -to contemplate Cora's face in profile.

Could a job be entirely bad if she were part of it?

'Michaels, who sat down immediately next to Grant, leaned forward to whisper in his ear. "Actually, it isn't a bad idea to have a woman along. The men, perhaps, will be more on their mettle. And it would please me."

"Is that why you made the pitch for her?"

"Actually, no. Duval is serious. He wouldn't go without her."

"Is he that dependent on her?"

"Perhaps not. But he's that intent on having his way. Especially against Reid. No love lost there."

Carter said, "To business. You can drink, or eat, if you wish, while this is going on. Do any of you have any urgent point to make?"

Grant said, suddenly, "I haven't volunteered, general. I decline the post and suggest you find a substitute."

"You're not a volunteer, Grant, and your offer to decline is declined. Gentlemen-and Miss Peterson-Mr Grant has been chosen to accompany the expedition for a variety of reasons. For one thing, it was he who brought Benes to this country, managing that assignment with complete skill."

All eyes turned to Grant, who felt himself wincing at the momentary expectation that there would be a polite patter of applause. There was none, and he relaxed.

Carter went on. "He is a communications expert and an experienced frogman. He has a record of resourcefulness and flexibility and is professionally capable of making instant decisions. For that reason I will place the power of making policy decisions in his hands once the voyage begins. Is that understood?"

It apparently was, and Grant, staring in annoyance at his fingertips, said, "Apparently it is up to the rest of you to do your jobs while I take care of emergencies. I am sorry but I wish to state for the record that I do not consider myself qualified for this post."

"The statement is recorded," said Carter, unembarrassed, "and we will go on. Captain Owens has designed an experimental submarine for oceanographic research. It is not ideally suited for the task at hand, but it is itself at hand, and there is no other vessel in existence that is better suited. Owens himself will, of course, be at the controls of his ship, the Proteus.

"Dr. Michaels will be the pilot. He has prepared and studied the map of Benes' circulatory system, which we will shortly consider. Dr. Duval and his assistant will be in charge of the actual operation, the removal of the clot.

"You all know the importance of this mission. We hope for a successful operation and for your safe return. There is the chance that Benes may die during the operation, but that becomes a certainty if the mission is not undertaken. There is a chance that the ship may be lost, but under the circumstances, I am afraid that ship and crew are expendable. The possible price is large but the gain we seek-I don't mean the CMDF only, but all mankind-is greater."

Grant muttered under his breath, "Yea, team."

Cora Peterson caught it and looked at him with brief penetration from under dark eyelashes. Grant flushed.

Carter said, "Show them the chart, Michaels."

Michaels pressed a button on the instrument before him and the wall lit up with the tri-dimensional map of Benes' circulatory system that Grant had last seen in Michaels' office. It seemed to rush toward them and enlarge as Michaels turned a knob. What was left of the circulatory network made up the clear delineation of a head and neck.

The blood vessels stood out with an almost fluorescent brilliance and then grid lines appeared across it. A thin dark arrow darted into the field, manipulated by the photo-pointer in Michaels' hand. Michaels did not rise but remained seated in his chair, one arm over its back.

"The clot, he said, "is there." It had not been visible to Grant's eyes, at least until it had been pointed out, but now that the black arrow delicately marked out its limits, Grant could see it-a small solid nodule plugging an arteriole.

"It represents no immediate danger to life, but this section of the brain" (the arrow danced about) "is suffering from nerve-compression and may already have experienced damage. Dr. Duval tells me that the effects may be irreversible in twelve hours or less. An attempt to operate in the ordinary manner will involve cutting through the skull either here, here, or here. In each of these three cases, unavoidable damage will be extensive and the results doubtful.

"On the other hand, we could attempt to reach the clot via the blood-stream. If we can enter the carotid artery here in the neck, we will be on a reasonably direct route to our destination." The flowing of the arrow along the line of the red artery, picking its way through the blueness of the veins, made it seem very easy.

"Michaels went on, "If, then, the Proteus and its crew are miniaturized and injected ..."

Owens spoke up suddenly. "Wait a while." His voice was harsh and metallic. "How far will we be reduced?"

"We'll have to be small enough to avoid activating the body's biological defenses. The overall length of the ship will be three micra."

"How much is that in inches?" interjected Grant.

"Just under a ten-thousandth of an inch. The ship will be about the size of a large bacterium."

"Well, then," said Owens. "If we enter an artery, we will be exposed to the full force of the arterial current."

"Not quite a mile an hour," said Carter.

"Never mind the miles per hour. We will be moving about 100,000 times the length of our ship each second. That will be equivalent, under ordinary circumstances, to moving 200 miles a second-or something like that. On our miniaturized scale we'll be moving a dozen times as fast as any astronaut over moved. At least."

"Undoubtedly," said Carter, "but what of it? Every red blood corpuscle in the blood-stream moves as quickly and the ship is much more sturdily built than the corpuscle."

"No, it is not," said Owens, passionately. "A red blood corpuscle contains billions of atoms, but the Proteus will crowd billions of billions of billions of atoms into the same space; miniaturized atoms, to be sure, but what of that. We will be made up of an immensely larger number of units than the red blood corpuscle and we'll be, flabbier for that reason. Furthermore, the red blood corpuscle is in an environment of atoms equal in size to those that make it up; we will be in an environment made up of what will be to us monstrous atoms."

Carter said, "Can you answer that, Max?"

Michaels harumphed. "I do not pretend to be as expert on the problems of miniaturization as Captain Owens. I expect that he is thinking of the report by James and Schwartz that fragility increases with intensity of miniaturisation."

"Exactly," said Owens.

"The increase is a slow one, if you remember, and James rind Schwartz had to make some simplifying assumptions in the course of their analysis which may prove to be not entirely valid. After all, when we enlarge objects, they certainly do not become less fragile."

"Oh, come on, we've never enlarged any object more than a hundred-fold," said Owens, contemptuously, "and here we are talking about miniaturizing a ship about a million times in linear dimensions. No one's ever gone that far, or oven anything close to that far, in either direction. The fact is that there isn't anyone in the world who can predict just how fragile we will become, or how well we can stand up to the pounding of the blood-stream, or even how we might respond to the action of a white blood corpuscle. Isn't that so, Michaels?"

Michaels said, "Well-yes."

Carter said, with what seemed rising impatience, "It would seem that the course of orderly experiment leading to so drastic a miniaturization has not yet been completed. We're in no position to carry through a program of such experimentation so we have to take our chances. If the ship does not survive, it doesn't.

"That bucks me up," muttered Grant.

Cora Peterson leaned toward him, whispering tightly

"Please, Mr. Grant, you're not on the football field."

"Oh, you know my record, miss?"

"Shh."

Carter said, "We are taking all the precautions we can. Benes will be in deep hypothermia for his own sake. By freezing him we will cut down the oxygen requirements to , the brain. That will mean the heartbeat will be drastically slowed and the velocity of the blood flow as well."

Owens said, "Even so, I doubt that we could survive the turbulence ..."

Michaels said, "Captain, if you stay away from the artery walls, you will be in the region of laminar flow-no turbulence to speak of. We will be in the artery only for minutes, and once in the smaller vessels, we will have no problem. The only place where we would not be able to avoid killing turbulence would be in the heart itself and we would nowhere near the heart. -May I continue, now?"

"Please do," said Carter.

"Having reached the clot, it will be destroyed by a laser beam. The laser and its beam, having been miniaturized in proportion, will not, if properly used - as in Duval's hand it is sure to be - do any damage to the brain or even the blood-vessel itself. Nor will it be necessary to demolish every vestige of the clot. It will be enough to break it up into fragments. The white blood-cells will then take care of it.

"We will leave the vicinity at once, of course, returning by way of the venous system, until we reach the base of the neck where we will be removed from the jugular vein."'

Grant said, "How will anyone know where we are and when?"

Carter said, "Michaels will be piloting you and see to it that you are in the right place at all times. You will be in, communication with us by radio ... "

"You don't know if that will work," put in Owens. There's a problem in adapting the radio waves across the miniaturization gap, and no one has ever tried this big a gap."

"True, but we will try. In addition, the Proteus is nuclear powered and we will be able to trace its radioactivity, also cross the gap. -You will have just sixty minutes, gentlemen...

Grant said, "You mean we have to complete the job and be out in sixty minutes."

"Exactly sixty. Your size will have been adjusted to that, which should be ample time. If you stay for a longer interval, you will start enlarging automatically. We can't keep you down longer. If we had Benes' knowledge we could keep you down indefinitely but if we had his knowledge ..."

"This trip would be unnecessary," said Grant, sardonically.

"Exactly. And if you begin enlarging within Benes' body, you will become large enough to attract the attention of the body defenses, and shortly thereafter, you will kill Benes. You will see to it that this does not happen."

Carter then looked about. "Any further remarks? -In that case, you will begin preparations. We'd like to make entry into Benes as quickly as possible."