"Yours?" said Morrison blankly.

"Of course. We have been reduced to this point by our central miniaturization device. Now the fine adjustments will be made by me."

Kaliinin murmured, "That is one of the things we must save our microfusion motors for as much as possible."

Morrison looked from one to another. "Do we have enough energy on board ship for further miniaturization? Surely the impression I got was that a vast quantity of energy was needed for -"

"Albert," said Boranova, "if gravitation were quantized, then it would take the same enormous amount of energy to reduce a mass by half, regardless of the original value of that mass. To reduce the mass of a mouse by half would take the same energy as was required to reduce the mass of an elephant by half. But the gravitational interaction is not quantized and, therefore, neither is mass loss. That means that the energy required for mass loss decreases with that loss - not entirely in proportion, but to an extent. We have so little mass now that it takes much less energy to miniaturize further."

Morrison said, "But since you've never miniaturized anything as large as this ship through so many orders of magnitude, you are depending on the extrapolation of data obtained for a much different size range."

(They're not speaking to an infant, he thought indignantly. I am their equal.)

"Yes," said Boranova. "We are taking the chance that the extrapolation will hold, that something new and unexpected will not surprise us. Still, we live in a Universe that faces us with uncertainties now and then. That can't be helped."

"But we all face death if something goes wrong."

"Didn't you know that?" said Boranova calmly. "Have you been uneasy about this fantastic voyage of ours simply for the pleasure of being uneasy? But we are not alone in this. If things go wrong and the stored energy of miniaturization is released, it will not only destroy us, but it may damage the Grotto to some extent. I'm sure that many an unminiaturized person out there is holding his or her breath and wondering if he or she will survive an explosion. You see, Albert, even those who are not undergoing the risks of miniaturization are not altogether safe."

Dezhnev turned and grinned widely. Morrison noted that one of his upper molars was capped and did not match the rather yellowish tint of his other teeth.

Dezhnev said, "Concentrate on the thought, my friend, that if something goes wrong, you will never know. My father used to say, 'Since we all must die, what better can we ask for than a quick and sudden death?'"

Morrison said, "Julius Caesar said the same thing."

Dezhnev said, "Yes, but we won't even have time to say, 'Et tu, Brute.'"

"There will be no death," said Konev sharply, "and it is foolish to speak of it. The equations are correct."

"Ah," said Dezhnev. "There was a time of superstition when people relied on the protection of God. Thank Equations we now have Equations to rely on."

"Not funny," said Konev.

"I didn't mean to be funny, Yuri. - Natasha, they're ready out there for us to proceed."

Boranova said, "Then there will be no further need to speculate. Here we go."

Morrison gripped his seat tightly, preparing himself, but he felt nothing happen. Up front, though, the round circle he had made out expanded and grew dimmer and dimmer as it moved very slowly backward until it could no longer be made out.

"Are we moving?" he asked automatically. It was the kind of question one was unable to refrain from asking, even though the answer was obvious.

"Yes," said Kaliinin, "and we are expending no energy in doing so. We are not battling the water molecules. We are being carried along by the water flow in the needle as the cylinder presses in slowly."

Morrison was counting to himself. It kept his mind more efficiently occupied than studying the second hand of his watch would have done.

When he reached a hundred, he said, "How long will it take?"

"How long will what take?" asked Kaliinin.

"When do we reach the bloodstream?"

Dezhnev said, "A few minutes. They are going very slowly, just in case there is some kind of microturbulence. As my father once said, 'It is slower, but better, to creep along the downward path than to leap over the cliff.'"

Morrison grunted, then said, "Are we still miniaturizing?"

Boranova answered from behind him. "No. We are down in the cellular range and that is far enough for our needs now."

Morrison was surprised to find that he was trembling. After all, so much was happening and so many new things existed to think about that he had somehow lacked the room to remain in terror. He was not terrified, at least not to an acute stage - yet for some reason he continued to tremble.

He attempted to will himself to relax. He tried to let himself droop, but that required more than an effort of will. It needed gravitational pull and there was none to speak of. He closed his eyes and slowed his breathing. He even tried humming, under his breath, the choral singing from Beethoven's Ninth Symphony.

Finally he felt himself forced into comment on the matter. "I'm sorry," he said. "I seem to be shaking."

Dezhnev snickered. "Aha! I wondered who would be the first to mention it."

Boranova said, "It's not you, Albert. We are all shaking slightly. It's the ship."

Morrison was at once elevated into fright. "Is something wrong with it?"

"No. It's just a matter of size. It's small enough to feel the effect of Brownian motion. You know what that is, don't you?"

It was a purely rhetorical question. Boranova would surely expect a high school student of physics to know what Brownian motion was, let alone Morrison, and yet Morrison found himself explaining it in his own mind - not in words, but as a flash of concept.

Every object suspended in a liquid is bombarded on all sides by the atoms or molecules of the liquid. These particles strike randomly and therefore unevenly, but the unevenness is so small compared to the total that it is unnoticeable and has no measurable effect. As an object grows smaller, however, the unevenness becomes greater among the smaller and smaller number of particles striking the object in a given time. The ship was small enough now to respond to the slight excesses of coillisions - first in one direction, then in another - randomly. It moved slightly in consequence, a random trembling.

Morrison said, "Yes, I should have thought of that. It will get worse if we continue to become smaller."

"Actually, it won't," said Boranova. "There will be other counteracting effects."

"I don't know of any," said Morrison, frowning.

"Nevertheless, there will be such effects."

"Leave it to the Equations," said Dezhnev in an affectedly pious tone. "The Equations know."

Morrison said, "I think this could make us seasick."

"It certainly would," said Boranova, "but there is a chemical treatment for that. We have been dosed with the same chemical that cosmonauts use against space sickness."

"Not I," said Morrison indignantly. "Not only haven't I been treated, I haven't even been forewarned."

"We told you as little as possible of the discomforts and dangers out of concern for your comfort, Albert. As for treatment, you consumed your dose with your breakfast. - How do you feel?"

Morrison, who had begun to feel a bit squeamish with all this talk about sickness, decided that he felt fine. Astonishing, he thought, the tyranny exerted over the body by the mind.

He said in a low voice, "Tolerable."

"Good," said Boranova, "because we are now in Academician Shapirov's bloodstream."

Morrison stared through the transparent wall of the ship.

Blood?