"Sir," the tech said suddenly, "I was under the impression that the roborocket scanners couldn't miss a life-pulse on a planet. I mean, making a complete circuit of the planet every ninety minutes, for a period of six months.... It's impossible for them to miss an uncatalogued life-form." "I know it is," said Jerry Norcriss, pushing blunt fingers through his shock of prematurely white hair. "Save for two precedents, I cannot conceive of any way in which this pulse could have been overlooked." "Two precedents, sir?" said the tech, intrigued both by the unsuspected fallibility of the scanner and by this unusual loquacity from the zoologist. Jerry removed his gaze from the screen and regarded the young man standing beside it. He made as if to reply, then thought better of it. Any out-going on his part was an effort. A big effort. And a danger. Only another Space Zoologist would understand the danger of speech, of letting loose, of relaxing for a moment that terrible vigil over one's personal psychic barricades. "Skip it," he said abruptly. The young ensign's smile tightened to obedience at the words. "Yes, sir," said the tech, with strained cordiality. "Will that be all, sir?" "Yes," said Jerry. Then, as the tech started out of the compartment, "No, wait. Tell Ollie Gibbs in the Ward Room to bring up a pot of coffee. Black." The man nodded, and went out the door, dogging it after him. Jerry listened to the booted feet clanking on their magnetic soles up the passageway of the spaceship, and sighed. The situation, in Jerry's experience, was fantastic. Only twice, in the history of Space Zoology, had there been oversights on the part of the scanners. One, almost comically, had been on Earth, when the scanners were first being tested. The chunky roborocket--its angles and bulges and tapering pickup-heads unsuitable for flight in any medium but airless space--had swept giddily about the planet, the sensitive pickup-heads recording and filing on microtape the patterns of the life-pulses of all sentient life below. And when the tape had been translated onto the IBM cards, and the cards run through the translation chambers, to get their incomprehensible sine-patterns changed into readable English, it was found that there was an animal missing. Six months of circling the planet had still left the index blank on that animal's expected check-pattern. The animal was the brown bear, of north central America. And only after agonizing hours of theorizing and worrying did someone come up with the answer to the dilemma: It had been a long, hard winter. The bears were in extended hibernation. Somehow, the fleeting flicker of their subdued life-pulses had never managed to correspond with the inquisitive sweep of the scanner-beams from the blackness of space overhead. And so, they'd been left off, as though they did not even exist.