The headset clicked。 It was Ricky。 〃They see fabulously；〃 he said。 〃It's what they were made to do； after all。 Eyesight's twenty…oh…five；〃 he said。 〃Fantastic resolution。 Better than any human。〃 I said； 〃And how do they do the imaging？〃 Because they were just a series of individual particles。 Like the rods and cones in the eye； central processing was required to form a picture from all the inputs。 How was that processing acplished？
Ricky coughed。 〃Uh 。。。 not sure。〃
Charley said； 〃It showed up in later generations。〃
〃You mean they evolved vision on their own？〃
〃Yeah。〃
〃And we don't know how they do it 。。。〃
〃No。 We just know they just do。〃
We watched as the swarm angled away from the wall； moved back near the rabbit； then returned to the wall once more。 The other swarms were farther down the building； doing the same thing。 Swirling out into the desert； then swirling back again。 Over the headset； Ricky said； 〃Why do you ask？〃
〃Because。〃
〃You think they'll find the rabbit？〃
〃I'm not worried about the rabbit；〃 I said。 〃Anyway； it looks like they already missed it。〃
〃Then what？〃
〃Uh…oh；〃 Mae said。
〃Shit；〃 Charley said； and he gave a long sigh。
We were looking at the nearest swarm； the one that had just bypassed the rabbit。 That swarm had moved out into the desert again； perhaps ten yards away from the rabbit。 But instead of turning back in its usual pattern； it had paused in the desert。 It didn't move； but the silvery column rose and fell。
〃Why is it doing that？〃 I said。 〃That up and down thing？〃
〃Something to do with imaging？ Focusing？〃
〃No；〃 I said。 〃I mean； why did it stop？〃
〃Program stall？〃
I shook my head。 〃I doubt it。〃
〃Then what？〃
〃I think it sees something。〃
〃Like what？〃 Charley said。
I was afraid I knew the answer。 The swarm represented an extremely high…resolution camera bined with a distributed intelligence network。 And one thing distributed networks did particularly well was detect patterns。 That was why distributed network programs were used to recognize faces for security systems； or to assemble the shattered fragments of archaeological pottery。 The networks could find patterns in data better than the human eye。 〃What patterns？〃 Charley said； when I told him。 〃There's nothing out there to detect except sand and cactus thorns。〃
Mae said； 〃And footprints。〃
〃What？ You mean our footprints？ From us walking over here？ Shit； Mae； the sand's been blowing for the last fifteen minutes。 There's no footprints left to find。〃 We watched the swarm hang there； rising and falling like it was breathing。 The cloud had turned mostly black now； with just an occasional glint of silver。 It had remained at the same spot for ten or fifteen seconds； pulsing up and down。 The other swarms were continuing in their zigzag course； but this one stayed where it was。
Charley bit his lip。 〃You really think it sees something？〃
〃I don't know；〃 I said。 〃Maybe。〃
Suddenly； the swarm rose up； and began to move again。 But it wasn't ing toward us。 Instead； it moved on a diagonal over the desert； heading back toward the door in the power building。 When it came to the door； it stopped； and swirled in place。 〃What the hell？〃 Charley said。
I knew what it was。 So did Mae。 〃It just tracked us；〃 she said。 〃Backward。〃 The swarm had followed the path we had originally taken from the door to the rabbit。 The question was； what would it do next？
The next five minutes were tense。 The swarm retraced its path； going back to the rabbit。 It swirled around the rabbit for a while； moving in slow semicircles back and forth。 Then once again it retraced the route back to the power station door。 It stayed at the door for a while； then returned to the rabbit。
The swarm repeated this sequence three times。 Meanwhile； the other swarms had continued their zigzagging around the building； and were now out of sight。 The solitary swarm returned to the door； then headed back to the rabbit again。
〃It's stuck in a loop；〃 Charley said。 〃It just does the same thing over and over again。〃
〃Lucky for us；〃 I said。 I was waiting to see if the swarm would modify its behavior。 So far it hadn't。 And if it had very little memory； then it might be like an Alzheimer's patient； unable to remember it had done all this before。
Now it was going around the rabbit； moving in semicircles。
〃Definitely stuck in a loop；〃 Charley said。
I waited。
I hadn't been able to review all the changes they'd made to PREDPREY； because the central module was missing。 But the original program had a randomizing element built into it； to handle situations exactly like this。 Whenever PREDPREY failed to attain its goal； and there were no specific environmental inputs to provoke new action； then its behavior was randomly modified。 This was a well…known solution。 For example； psychologists now believed a certain amount of random behavior was necessary for innovation。 You couldn't be creative without striking out in new directions； and those directions were likely to be random…
〃Uh…oh；〃 Mae said。
The behavior had changed。
The swarm moved in larger circles； going around and around the rabbit。 And almost immediately； it came across another path。 It paused a moment； and then suddenly rose up； and began to move directly toward us。 It was following exactly the same path we had taken； walking to the shed。
〃Shit；〃 Charley said。 〃I think we're fucked。〃
Mae and Charley rushed across the room to look out the window。 David and Rosie stood and peered out the window above the sink。 And I started to shout： 〃No； no！ Get away from the windows！〃
〃What？〃
〃It's visual； remember？ Get away from the windows！〃
There was no good place to hide in the storage room； not really。 Rosie and David crawled under the sink。 Charley pushed in beside them； ignoring their protests。 Mae slipped into the shadows of one corner of the room； easing herself into the space where two shelves didn't quite meet。 She could only be seen from the west window； and then not easily。 The radio crackled。 〃Hey guys？〃 It was Ricky。 〃One's heading for you。 And uh 。。。 No 。。。 two others are joining it。〃
〃Ricky；〃 I said。 〃Go off air。〃
〃What？〃
〃No more radio contact。〃
〃Why？〃
〃Off； Ricky。〃
I dropped down on my knees behind a cardboard carton of supplies in the main room。 The carton wasn't large enough to hide me entirely…my feet stuck out…but like Mae； I wasn't easily seen。 Someone outside would have to look at an angle through the north window to see me。 In any case； it was the best I could do。
From my crouched position； I could just see the others huddled beneath the sink。 I couldn't see Mae at all； unless I really stuck my head around the corner of the carton。 When I did； she looked quiet； posed。 I ducked back and waited。
I heard nothing but the hum of the air conditioner。
Ten or fifteen seconds passed。 I could see the sunlight streaming in through the north window above the sink。 It made a white rectangle on the floor to my left。 My headset crackled。 〃Why no contact？〃
〃Jesus fucking A；〃 Charley muttered。
I put my finger to my lips； and shook my head。
〃Ricky；〃 I said； 〃don't these things have auditory capacity？〃
〃Sure； maybe a little； but…〃
〃Be quiet and stay off。〃
〃But…〃
I reached for the transmitter at my belt； and clicked it off。 I signaled the others beneath the sink。 They each turned their transmitters off。
Charley mouthed something to me。 I thought he mouthed； 〃That fucking guy wants us killed。〃
But I couldn't be sure。
We waited。
It couldn't have been more than two or three minutes； but it seemed forever。 My knees began to hurt on the hard concrete floor。 Trying to get more fortable； I shifted my position cautiously； by now I was sure the first swarm was in our vicinity。 It hadn't appeared at the windows yet； and I wondered what was taking so long。 Perhaps as it followed our path it had paused to inspect the cars。 I wondered what swarm intelligence would make of an automobile。 How puzzling it must look to that high…resolution eye。 But maybe because the cars were inanimate； the swarm would ignore them as some sort of large； brightly colored boulders。 But still 。。。 What was taking so long？
My knees hurt more with every passing second。 I changed my position； putting weight on my hands and raising my knees like a runner at the blocks。 I had a moment of temporary relief。 I was so focused on my pain that I didn't notice at first that the glaring white rectangle on the floor was turning darker at the center； and spreading out to the sides。 In a moment the entire rectangle turned dull gray。
The swarm was here。
I wasn't certain； but I fancied that beneath the hum of the air conditioner was a deep thrumming sound。 From my position behind the crate； I saw the window above the sink grow progressively darker from swirling black particles。 It was as if there was a dust storm right outside。 Inside the shed it was dark。 Surprisingly dark。
Underneath the sink； David Brooks began to moan。 Charley clapped his hand over his mouth。 They looked upward； even though the sink blocked their view of the window above them。 And then the swarm vanished from the window； as quickly as it had e。 Sunlight poured in again。
Nobody m