another clue.

"Here, then, we have a race which does not use metal or the longer electromagnetic radiations—I have no doubt that they can use the shorter ones. And they attack another ship.

"Let's get back to that because it's important; it gave me my first clue. I wondered why they attacked. There could be no reason to attack a ship that might be better armed than you, even if your psychology is bred toward pure hate.

"There is only one good reason, and it is the same reason that made us fight back instead of running. We had a colony in that system, and we didn't want the enemy to know it. If they had found us in a system where we had no colonies, we would have turned tail and run—the only sensible thing to do.

"But we didn't—and neither did they.

"Therefore, they, too, have a colony in that system!"

The Speaker said: "Where? Therbis is the only planet with—" His voice trailed off as he suddenly saw the truth.

Parmay nodded. "All this time, we've been assuming that the aliens were after the same planets we were. But every bit of evidence indicates that they live on the ammonia-methane giants!"

He paused to light a cigarette, then went on: "Alina Starrnel, my wife, has done some checking on the conditions that obtain in such an atmosphere. Alina—" he nodded toward her.

She looked at them from her cool green eyes. "The atmospheres of ammonia-methane giants are such that the surface suffers from almost unbelievable electric storms. Every sunspot on the primary, every wind, every slight change in temperature causes lightnings and electrical displays such as we on Earth can't imagine. The atmosphere itself is a semi-conductor.

"Therefore, it would be almost impossible for them to have radio communication as we know it.

"There are two reasons why metals are not used for construction on such planets. One: the heavy, metal-bearing core of the giants is buried beneath thousands of miles of ice. Two: metals wouldn't stand the strain. At the temperatures prevailing on those planets, most metals are so brittle that they'd shatter under the loads that the unimaginable gravitational pull would cause.

"Plastics are a different matter. Any life that would evolve on such a world would be able to synthesize hard, tough materials in 

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