ation； they were well concealed but quite effective。 Then closer in； impedance sensors were buried in the ground； they signaled the approach of any animal life weighing more than one hundred pounds。 The sensors ringed the base。
〃We've never missed anything yet；〃 the man said。 〃And if we do 。 。 。 〃 He shrugged。 To Leavitt： 〃Going to show him the dogs？〃
〃Yes；〃 Leavitt said。
They walked through into an adjoining room。 There were nine large cages there； and the room smelled strongly of animals。 Hall found himself looking at nine of the largest German shepherds he had ever seen。
They barked at him as he entered； but there was no sound in the room。 He watched in astonishment as they opened their mouths and threw their heads forward in a barking motion。
No sound。
〃These are Army…trained sentry dogs；〃 the security man said。 〃Bred for viciousness。 You wear leather clothes and heavy gloves when you walk them。 They've undergone laryngectomies； which is why you can't hear them。 Silent and vicious。〃
Hall said； 〃Have you ever； uh； used them？〃
〃No；〃 the security man said。 〃Fortunately not。〃
***
They were in a small room with lockers。 Hall found one with his name on it。
〃We change in here；〃 Leavitt said。 He nodded to a stack of pink uniforms in one corner。 〃Put those on； after you have removed everything you are wearing。〃
Hall changed quickly。 The uniforms were loose…fitting one…piece suits that zipped up the side。 When they had changed they proceeded down a passageway。
Suddenly an alarm sounded and a gate in front of them slid closed abruptly。 Overhead； a white light began to flash。 Hall was confused； and it was only much later that he remembered Leavitt looked away from the flashing light。
〃Something's wrong；〃 Leavitt said。 〃Did you remove everything？〃
〃Yes；〃 Hall said。
〃Rings； watch； everything？〃
Hall looked at his hands。 He still had his watch on。
〃Go back；〃 Leavitt said。 〃Put it in your locker。〃
Hall did。 When he came back； they started down the corridor a second time。 The gate remained open； and there was no alarm。
〃Automatic as well？〃 Hall said。
〃Yes；〃 Leavitt said。 〃It picks up any foreign object。 When we installed it； we were worried because we knew it would pick up glass eyes； cardiac pacemakers； false teeth anything at all。 But fortunately nobody on the project has these things。〃
〃Fillings？〃
〃It is programmed to ignore fillings。〃
〃How does it work？〃
〃Some kind of capacitance phenomenon。 I don't really understand it；〃 Leavitt said。
They passed a sign that said：
YOU ARE NOW ENTERING LEVEL I PROCEED DIRECTLY TO IMMUNIZATION CONTROL
Hall noticed that all the walls were red。 He mentioned this to Leavitt。
〃Yes；〃 Leavitt said。 〃All levels are painted a different color。 Level I is red； II； yellow； III； white； IV； green； and V； blue。〃
〃Any particular reason for the choice？〃
〃It seems；〃 Leavitt said； 〃that the Navy sponsored some studies a few years back on the psychological effects of colored environments。 Those studies have been applied here。〃
They came to Immunization。 A door slid back revealing three glass booths。 Leavitt said； 〃Just sit down in one of them。〃
〃I suppose this is automatic； too？〃
〃Of course。〃
Hall entered a booth and closed the door behind him。 There was a couch； and a mass of plex equipment。 In front of the couch was a television screen； which showed several lighted points。
〃Sit down；〃 said a flat mechanical voice。 Sit down。 Sit down。〃
He sat on the couch。
〃Observe the screen before you。 Place your body on the couch so that all points are obliterated。〃
He looked at the screen。 He now saw that the points were arranged in the shape of a man。
He shifted his body； and one by one the spots disappeared。 〃Very good；〃 said the voice。 〃We may now proceed。 State your name for the record。 Last name first； first name last。〃
〃Mark Hall；〃 he said。
〃State your name for the record。 Last name first； first name last。〃
Simultaneously； on the screen appeared the words：
SUBJECT HAS GIVEN UNCODABLE RESPONSE
〃Hall； Mark。〃
〃Thank you for your cooperation； 〃 said the voice。 〃Please recite； 'Mary had a little lamb。' 〃
〃You're kidding；〃 Hall said。
There was a pause； and the faint sound of relays and circuits clicking。 The screen again showed：
SUBJECT HAS GIVEN UNCODABLE RESPONSE
〃Please recite。〃
Feeling rather foolish； Hall said； 〃Mary had a little lamb； her fleece was white as snow； and everywhere that Mary went； the lamb was sure to go。〃
Another pause。 Then the voice： 〃Thank you for your cooperation。 〃 And the screen said：
ANALYZER CONFIRMS IDENTITY
HALL； MARK
〃Please listen closely；〃 said the mechanical voice。 〃You will answer the following questions with a yes or no reply。 Make no other response。 Have you received a smallpox vaccination within the last twelve months？〃
〃Yes。〃
〃Diphtheria？〃
〃Yes。〃
〃Typhoid and paratyphoid A and B？〃
〃Yes。〃
〃Tetanus toxoid？〃
〃Yes。〃
〃Yellow fever？〃
〃Yes； yes； yes。 I had them all。〃
〃Just answer the question please。 Uncooperative subjects waste valuable puter time。〃
〃Yes；〃 Hall said； subdued。 When he had joined the Wildfire team； he had undergone immunizations for everything imaginable； even plague and cholera； which had to be renewed every six months； and gamma…globulin shots for viral infection。
〃Have you ever contracted tuberculosis or other mycobacterial disease； or had a positive skin test for tuberculosis？
〃No。〃
〃Have you ever contracted syphilis or other spirochetal disease； or had a positive serological test for syphilis？〃
〃No。〃
〃Have you contracted within the past year any gram…positive bacterial infection； such as streptococcus； staphylococcus； or pneumococcus？〃
〃No。〃
〃Any gram…negative infection； such as gonococcus； meningeococcus； proteus； pseudomonas； salmonella； or shigella？〃
〃No。〃
〃Have you contracted any recent or past fungal infection； including blastomycosis； histoplasmosis； or coccidiomycosis； or had a positive skin test for any fungal disease？〃
〃No。〃
〃Have you had any recent viral infection； including poliomyelitis； hepatitis； mononucleosis； mumps； measles； varicella； or herpes？〃
〃No。〃
〃Any warts？〃
〃No。〃
〃Have you any known allergies？〃
〃Yes； to ragweed pollen。〃
On the screen appeared the words：
ROGEEN PALEN
And then after a moment：
UNCODABLE RESPONSE
〃Please repeat your response slowly for our memory cells。〃 Very distinctly； he said； 〃Ragweed pollen。〃 On the screen：
RAGWEED POLLEN
CODED
〃Are you allergic to albumen？〃 continued the voice。
〃No。〃
〃This ends the formal questions。 Please undress and return to the couch； obliterating the points as before。〃
He did so。 A moment later； an ultraviolet lamp swung out on a long arm and moved close to his body。 Next to the lamp was some kind of scanning eye。 Watching the screen he could see the puter print of the scan； beginning with his feet。
＇graphic of a foot＇
〃This is a scan for fungus；〃 the voice announced。 After several minutes； Hall was ordered to lie on his stomach； and the process was repeated。 He was then told to lie on his back once more and align himself with the dots。
〃Physical parameters will now be measured；〃 the voice said。 〃You are requested to lie quietly while the examination is conducted。〃
A variety of leads snaked out at him and were attached by mechanical hands to his body。 Some he could understand the half…dozen leads over his chest for an electrocardiogram； and twenty…one on his head for an electroencephalogram。 But others were fixed on his stomach； his arms； and his legs。
〃Please raise your left hand；〃 said the voice。
Hall did。 From above； a mechanical hand came down； with an electric eye fixed on either side of it。 The mechanical hand examined Hall's。
〃Place your hand on the board to the left。 Do not move。 You will feel a slight prick as the intravenous needle is inserted。〃
Hall looked over at the screen。 It flashed a color image of his hand； with the veins showing in a pattern of green against a blue background。 Obviously the machine worked by sensing heat。 He was about to protest when he felt a brief sting。
He looked back。 The needle was in。
〃Now then； just lie quietly。 Relax。〃
For fifteen seconds； the machinery whirred and clattered。 Then the leads were withdrawn。 The mechanical hands placed a neat Band…Aid over the intravenous puncture。
〃This pletes your physical parameters；〃 the voice said。
〃Can I get dressed now？〃
〃Please sit up with your right shoulder facing the television screen。 You will receive pneumatic injections。〃
A gun with a thick cable came out of one wall； pressed up against the skin of his shoulder； and fired。 There was a hissing