Hope which was snapped out when Ali brought the news that Stotz could not be roused and must have taken ill during a sleep period.  One more inert patient was added to the list—­and nothing learned about how he was infected.  Except that they could eliminate Sinbad, since the cat had been in custody during the time Stotz had apparently contracted the disease.

Weeks, Ali and Dane, though they were in constant contact with the sick men, and though Dane had repeatedly handled Sinbad, continued to be immune.  A fact, Dane thought more than once, which must have significance—­if someone with Tau’s medical knowledge had been able to study it.  By all rights they should be the most susceptible—­but the opposite seemed true.  And Wilcox duly noted that fact among the data they had recorded.

It became a matter of watching each other, waiting for another collapse.  And they were not surprised when Tang Ya reeled into the mess, his face livid and drawn with pain.  Rip and Dane got him to his cabin before he blacked out.  But all they could learn from him during the interval before he lost consciousness was that his head was bursting and he couldn’t stand it.  Over his limp body they stared at one another bleakly.

“Six down,” Ali observed, “and six to go.  How do you feel?”

“Tired, that’s all.  What I don’t understand is that once they go into this stupor they just stay.  They don’t get any worse, they have no rise in temperature—­it’s as if they are in a modified form of cold sleep!”

“How is Tang?” Rip asked from the corridor.

“Usual pattern,” Ali answered, “He’s sleeping.  Got a pain, Fella?”

Rip shook his head.  “Right as a Com-unit.  I don’t get it.  Why does it strike Tang who didn’t even hit dirt much—­and yet you keep on—?”

Dane grimaced.  “If we had an answer to that, maybe we’d know what caused the whole thing—­”

Ali’s eyes narrowed.  He was staring straight at the unconscious Com-tech as if he did not see that supine body at all.  “I wonder if we’ve been salted—­” he said slowly.

“We’ve been what?” Dane demanded.

“Look here, we three—­with Weeks—­drank that brew of the Salariki, didn’t we?  And we—­”

“Were as sick as Venusian gobblers afterwards,” agreed Rip.

Light dawned.  “Do you mean—­” began Dane.

“So that’s it!” flashed Rip.

“It might just be,” Ali said.  “Do you remember how the settlers on Camblyne brought their Terran cattle through the first year?  They fed them salt mixed with fansel grass.  The result was that the herds didn’t take the fansel grass fever when they turned them out to pasture in the dry season.  All right, maybe we had our ‘salt’ in that drink.  The fansel-salt makes the cattle filthy sick when it’s forced down their throats, but after they recover they’re immune to the fever.  And nobody on Camblyne buys unsalted cattle now.”

“It sounds logical,” admitted Rip.  “But how are we going to prove it?”