upward. At last he stopped. "Is this where feeling ends?"

"I think so. Touch it. Yeah. It's dead below there."

"Good. Then we've got it pegged. It's the Bubble Death."

Bolden showed concern and the doctor laughed. "Don't worry. It's called that because of the way it looks through the X-ray microscope. It's true that it killed the scouting expedition that discovered the planet, but it won't get you."

"They had antibiotics. Neobiotics, too."

"Sure. But they had only a few standard kinds. Their knowledge was more limited and they lacked the equipment we now have."

The doctor made it sound comforting. But Bolden wasn't comforted. Not just yet.

"Sit up and take a look," said Kessler, bending the eyepiece around so Bolden could use it. "The dark filamented lines are nerves. See what surrounds them?"

Bolden watched as the doctor adjusted the focus for him. Each filament was covered with countless tiny spheres that isolated and insulated the nerve from contact. That's why he couldn't feel anything. The spherical microbes did look like bubbles. As yet they didn't seem to have attacked the nerves directly.

While he watched, the doctor swiveled out another eyepiece for his own use and turned a knob on the side of the machine. From the lens next to his arm an almost invisible needle slid out and entered his flesh. Bolden could see it come into the field of view. It didn't hurt. Slowly it approached the dark branching filament, never quite touching it.

The needle was hollow and as Kessler squeezed the knob it sucked in the spheres. The needle extended a snout which crept along the nerve, vacuuming in microbes as it moved. When a section had been cleansed, the snout was retracted. Bolden could feel the needle then.

When the doctor finished, he laid Bolden's hand back at his side and wheeled the machine to the wall, extracting a small capsule which he dropped into a slot that led to the outside. He came back and sat down.

"Is that what you're going to do?" asked Bolden. "Scrape them off?"

"Hardly. There are too many nerves. If we had ten machines and enough people to operate them, we might check the advance in one arm. That's all." The doctor leaned back in the chair. "No. I was collecting a few more samples. We're trying to find out what the microbes react to."

"More samples? Then you must have taken others."

"Certainly. We put you out for a while to let you rest." The chair came down on four legs. "You've got a mild case. Either that or you have a strong natural immunity. It's now been three days since you reported the first symptoms and it isn't very advanced. It killed the entire scouting expedition in less time than that."

Bolden looked at the ceiling. Eventually they'd find a cure. But would he be alive that long?

"I suspect what you're thinking," said the doctor. "Don't overlook our special equipment. We already have specimens in the sonic accelerator. We've been able to speed up the life processes of the microbes about ten times. Before the day is over we'll know which of our anti and neobiotics they like the least. Tough little things so far—unbelievably tough—but you can be sure we'll smack them."

His mind was active, but outwardly Bolden was quiescent as the doctor continued his explanation.

The disease attacked the superficial nervous system, beginning with the extremities. The bodies of the crew of the scouting expedition had been in an advanced state of decomposition when the medical rescue team reached them and the microbes were no longer active. Nevertheless it was a reasonable supposition that death had come shortly after the invading bacteria had reached the brain. Until then, though nerves were