"Watch."

"I can't see anything."

"Nor can I yet, but I can hear it and I can see the places where it hits the wall of the jar. There's something under the jar. Something that Buster has been seeing all along."

"What?"

Thompson pointed at the jar. "One or several of those things came into the ship when the lock was open. We couldn't see them, didn't know they existed. But Buster saw them. He caught one of them in this cabin soon after we took off. I thought he was playing a game to amuse himself, or--" He broke off. From the back of his mind came a fragment of history, now in the forgotten Dark Ages of Earth, whole populations had been ravaged and destroyed by a fever that was carried by some kind of an insect. Did they have some kind of an insect under his jar?

Holding his breath, Thompson watched.

The pounding against the walls of the jar was growing weaker. Then it stopped. On the desk top, a smudge appeared. Wings quavered there, wings that shifted through a range of rainbow colors as they became visible.

As the flutter of the wings stopped the whole creature became visible.

Made up of some kind of exceedingly thin tissue that was hardly visible, it was about as big as a humming bird.

Silence held the room. Thompson was aware of his eyes coming to focus on the long pointed bill of the creature.

"Alive it was not visible at all," Fortune whispered. "Dead, you can see it." His voice lifted, picked up overtones of terror. "Say an hour or so ago Ross was complaining that something had bit him."

Like the last remnant of a picture puzzle fitting together, something clicked in Thompson's mind. "And Kurkil. While we were out of the ship something bit him."

Silence again. His eyes went from Neff to Fortune. "Did--"

They shook their heads.

"Then that ties up the package," Thompson whispered. "This creature carried the virus, or poison, or whatever it was. Without being bitten, the virus cannot spread. We've found the cause. We've got it licked."

He was aware of sweat appearing on his face, the sweat of pure relief.

He sank back into his chair. Buster, recovering from his indignity at the outrage he had suffered, jumped to the top of the desk, settled down with his nose against the gla.s.s, watching the dead creature inside the bell jar.

"He caught one of those things right in this cabin," Thompson whispered.

A shudder pa.s.sed over him and was gone. He had been so close to death, and had not known it. Buster had saved him.

Instead of seeking protection from him, the cat, in a sense, had been protecting him. His gaze centered fondly on the cat.

"What if there are more of those things in the ship?" Fortune spoke.

"We can solve that one," Thompson spoke. "s.p.a.ce suits. And, now that we know what we're looking for, we can clean out the ship. If we don't, Buster will do it for us."

"s.p.a.ce suits!" As if he had heard no more than those two words, Fortune ran from the room. He returned with three suits. They hastily donned them.

"No d.a.m.ned bug can bite through one of these things," Neff said exultantly. "Say, what about Grant? Hadn't we better take him a suit too?"

"I should say so. Fortune...." But Fortune was already leaving the room on his errand. Thompson snapped open the intercom system. "Grant?"

"Yes, what is it?"

"We've found the cause and we've got the disease licked."

Grant's voice a shout coming back from the control room. "Thank G.o.d.

I've been sitting here watching Sol grow bigger and bigger...." His voice suddenly choked, went into silence, then came again, asking a question. "Is it all right to change course now?"

"Definitely it's all right," Thompson answered. "In fact, it's an order."

An instant later, the ship groaned as the direction of flight was shifted. Thompson took a deep breath, was aware that Neff was staring at him. "What was that he said about watching Sol grow bigger and bigger?

Say, what course were we on?"

"Collision course with the sun," Thompson answered.

"What?" Neff gasped. "Do you mean to say that you were going to throw the ship into the sun?"

Slowly Thompson nodded. "I didn't know whether we would be alive or not but I didn't want this ship to enter Sol Cl.u.s.ter and turn loose there the virus that had already depopulated a planet."

He spoke slowly, with the sure knowledge of a desperate danger safely pa.s.sed. Neff stared at him from round and frightened eyes.

On the desk top Buster gave up his vigil, meowed, and jumped into the captain's lap. With the thick gloves of his s.p.a.ce suit clad hands, Thompson fondly stroked him.

Buster arched his back in grateful appreciation and began to purr.