He hung up the receiver.

Removing the handkerchief, still shaking, he got to his feet, left the public vidphone booth. Well, he almost had done it. Tried; I did try, he said to himself. So close.

Then a wire? Or a special registered 'stant mail letter, no name signed, letters cut from homeopapes.

Can't, he realized; can't ever do it. Darn sorry, Louis Runcible; the bonds are too strong. The ties; they're too long, old, tight. I have introjected them and now they act as a part of me; they live here inside, within me. Life-long. Now and now on.

He walked unhastily, feeling a membrane of numbness transport itself with him, hovering as he walked up the corridor away from the vidphone booth. Back to his own office. As if nothing had happened.

Nothing had. It was gall-bitter truth: nothing, nothing at all.

So it would progress on its own, the thing. Force he did not understand, substantial but remote, eluding, butterflylike, his perception even at the edge: shapes that winged across the sky of his life and left no trail, no sensation; he felt blind and afraid and helpless. And still he walked. Because it was natural. And, for him, there was nothing else.

And as he walked, it moved. Stirred; he felt it roll forth. Coasting in a direction which was unveering: straight ahead.

Across the cropped green lawn, temporarily abandoned now because this was night and the leady gardeners had gone off elsewhere into storage sheds and immobility, the machine coasted on rubber, hard wheels; it made no noise, orienting itself by the rebound of the radarlike signals which it emitted at a frequency not customarily utilized. The signals had begun to return now in a succession which informed the machine that the large stone building--the tropism of phase one of its homeostatic but many-sectioned journey--lay properly on its path, and it began to slow until at last it bumped soundlessly against the wall of the building, came to rest for a moment as the next stage of its cycle rotated, in the form of a cam, into position.

Click. Phase two had begun.

By means of suction discs extended from stiff radii of a power-driven revolving central shaft the machine ascended the vertical surface until it arrived at a window.

Entering the building by means of the window posed no problem, despite the fact that the window, in its aluminum frame, was securely locked; the machine simply subjected the glass to sudden enormous heat--the glass became molten, dripped away like honey, leaving a wide, empty hole dead center, where the core of the heat beam had been directed. The machine, with no difficulty, traveled off the vertical, over the aluminum frame--

And, poised momentarily on the aluminum frame, it performed phase four of its total operation; it exerted the precise pressure on the rather soft metal that a two-hundred-and-twenty pound weight, if resting there, would create; the frame yielded, bent until warped-- satisfied, the machine then crawled on vertically once more by means of its radii of suction cups, until it reached the floor of the room.

An interval passed in which the machine remained inoperative, at least from external appearances. But within it seletoidal switches opened and shut. At last an iron oxide tape moved past a playback head; through an audio system current passed from transformer to speaker and the machine abruptly said in a low, muffled, but whiny voice, "Damn it." The tape, expended, fell into a reservoir within the machine and was incinerated.

The machine, on its small hard-rubber wheels, again rolled forward, again orienting itself batlike, by its radar emanations. To its right lay a low table. The machine halted at the table and seletoidal switches once more opened and shut. And then the machine extended a pseudopodium, the end of which it pressed firmly against the edge of the table, as if, for a moment, it had involuntarily eased itself of the burden of its own excessive weight, had rested there before going on. And now it went on. Carefully. Because the ultimate tropism, the man, was not far off. The man slept in the next room; the machine had picked up the sound of his respiration and the emanations of warmth from his body. Attracted by both, tropisms of each sort operating in synchronicity, the machine turned in that direction.

As it passed a closet door it paused, click-clicked, and then released an electrical impulse corresponding to the Alpha wave of a human brain--of, in fact, one particular human brain.

Within the closet a recording instrument received the impulse, deposited it as a permanent record sealed within a locked case buried deep within the wall, inaccessible except through extensive drilling or by the proper key. The machine, however, did not know that and if it had it would not have cared; it did not inquire into these ramifications; they were not its proper concern.

It rolled on.

As it passed through the open doorway into the bedroom it halted, reared back on its hind wheels, extended a pseudopodium which deftly--but at the loss of several seconds--lodged a single strand of artificial cloth-fiber into the brass lock fittings of the frame. This done to its satisfaction it again continued on, pausing once to excrete three hairs and a fleck of dried scalp material; otherwise it had no need to interrupt its double tropism toward the man asleep in the bed.

At the edge of the bed it stopped entirely. The most intricate part of its overall cycle now came, by means of a rapid series of switch openings and closings, into play. The case forming the hull of the machine radically changed shape as a slow, fastidiously regulated warmth softened the plastic; the machine became thin, extended, and then, this accomplished again tipped back onto its rear wheels. The effect, had anyone seen it, would have been comic; the machine now swayed like a snake, barely able to maintain its balance--it came to the verge of falling first to one side and then to the other, for, slender and elongated as it was, it no longer possessed a wide resting base. However, it was too busy to preoccupy itself with the problem of its lateral oscillations; the master circuit which controlled it, the _clock_, as the wartime technicians who had built it had called that assembly, endeavored to obtain something more vital than upright balance.

The machine, having completed its mobile, ambulatory phases, based on the doubly reinforcing tropisms of heat and respiratory rhythm, was attempting to locate exactly the beating heart of the man asleep in the bed.

This, after an interval of minutes, it accomplished; it locked its percept system, focused on the beating heart: the stethoscopic effect of its sensors registered deep within it, and then the next phase came swiftly. It could not hesitate, now that the beating heart had been located; it had to act at once or not at all.

It released, from an aperture at its upper lid, a cyanide-tipped self-propelling dart. Traveling at extremely slow speed, so that corrections of its trajectory could be achieved even at the last fractional second, the dart made its way from the upended machine, veered slightly as signals from the machine indicated the need of a minor correction--and then its needle nose penetrated the chest of the sleeping man.

Instantly the dart ejected its freight of poison.

The man, without waking, died.

And, at his throat, a complicated but extremely fine band, as fine as gold wire, but containing a variety of functioning electronic valves and surge gates, emitted an elaborate series of radio signals which were without time lapse accepted by larger units bolted to the underside of the bed. These larger units, triggered off by the fine-spun collar which had reacted immediately upon the cessation of blood circulation and heart action, at once sent out their own signals.