"After twenty-two years of drinking and arguing with him, we've begun—God help me!—to think alike."

I tried my own hand just once.

"Gaffa says that they are exactly identical so far as outside appearance goes," I said. "But he may be wrong, or lying. Maybe we'd better check for ourselves."

The Haslops raised a howl, of course, but it did them no good. Gibbons and Corelli and I ganged them one at a time—the Quack refused to help for fear of being contaminated—and examined them carefully. It was a lively job, since both of them swore they were ticklish, and under different circumstances it could have been embarrassing.

But it settled one point. Gaffa hadn't lied. They were absolutely identical, as far as we could determine.

We had given it up and were resting from our labors when Gaffa came grinning out of the darkness and brought us a big crystal pitcher of something that would have passed for a first-class Planet Punch except that it was nearer two-thirds alcohol than the fifty-fifty mix you get at most interplanetary ginmills.

The two Haslops had a slug of it as a matter of course, being accustomed to it, and the rest of us followed suit. Only the Quack refused, turning green at the thought of all the alien bacteria that might be swimming around in the pitcher.

A couple of drinks made us feel better.

"I've been thinking," Captain Corelli said, "about what Gaffa said when he limited the time of the test, that we might or might not discover the reason for ourselves. Now what the hell did the grinning heathen mean by that? Is there a reason, or was he only dragging a red herring across the bogus Haslop's track?"

Gibbons looked thoughtful. I sat back while he pondered and watched the Quack, who was swallowing another antibiotic capsule.

"Wait a minute," Gibbons exclaimed. "Captain, you've hit on something there!"

He stared at the Haslops. They stared back, unimpressed.

"Gaffa said you two were exactly alike outside," Gibbons said. "And we've proved it. Does that mean you're not alike inside?"

"Sure," one of them said. "But what of it? You're sure as hell not going to cut one of us open to see!"

"You're confusing the issue," Gibbons snapped. "What I'm getting at is this—if you two aren't made alike inside, then you can't possibly exist on the same sort of diet. One of you eats the same sort of food as ourselves. The other can't. But which is which?"

One of the Haslops pointed a quivering finger at the other. "It's him!" he said. "I've watched him drink his dinner for twenty-two years—he's the fake!"

"Liar!" the other one yelled, springing up. Corelli stepped between them and the second Haslop subsided, grumbling. "It's true enough, only he's the one that drinks his meals. This stuff in the pitcher is the food he lives on—alcohol for energy, with minerals and other stuff dissolved in it. I drink it with him for kicks, but that phony can't eat anything else."

Corelli snapped his fingers.

"So that's why they limited our time, and why they brought this stuff—to keep their fake Haslop refueled! All we've got to do to separate our men now is feed them something solid. The one that eats it is the real Haslop."

"Sure, all we need now is some solid food," I said. "You don't happen to have a couple of sandwiches on you, do you?"

Everybody got quiet for a couple of minutes, and in the silence the Quack surprised us all by deciding to speak up.

"Since I'm stuck here for life," he said, "a few germs more or less won't matter much. Pass me the pitcher, will you?"

He took a man-sized slug of the fiery stuff without even wiping off the pitcher's rim.

After that we gave it up, as who wouldn't have? Captain Corelli said the hell with it and took such a slug out of the pitcher that the two Haslops yelled murder and grabbed it quick themselves, and from then on we just sat around and drank and talked and waited for the