by Hal Clement
"Try to be back by sundown," she called to Bob over her shoulder as she reached the trees. "You still have to pack, and you'll have to be up early in the morning." Bob nodded, with his mouth full, and turned back to the food-laden blanket.
After disposing of the meal, the boys sat, talked, and dozed for the standard hour after eating; then they returned to the water, where they indulged further in games of violence; and at last, realizing that the abrupt tropical night would soon be upon them, they gathered up the blanket and started for the road and their respective dwellings. They were rather silent now, with the awkwardness natural to their ages when faced by a situation which adults would treat either emotionally or with studied casualness. The farewells, as they passed their respective dwellings, were brief and accompanied by reiterated and reciprocated promises to "write as soon as you can."
Bob, proceeding at last alone to his own house, felt the mixture of regret and pleasurable anticipation which he had come to associate with these occasions. By the tune he reached home, though, the latter feeling had gained the ascendant, and he was looking forward with considerable eagerness to meeting again the school friends he had not seen for more than two months. He was whistling cheerfully as he entered the house.
The packing, done with the tactful assistance of his mother, was quickly completed, and by nine o'clock he was in bed and asleep. He himself considered the hour rather early, but he had learned the value of obedience at certain times very early in life.
The Hunter was able to remain quiescent, as he had hoped, for some hours-till well after Bob was asleep, in fact. He could not, however, last an entire day; for no matter how quiet he remained, the mere fact of living used up some energy and consequently some oxygen.
Eventually he realized his store was growing low, and he knew it would be necessary to establish a supply before the need became desperate.
He knew, of course, that his host was asleep, but this in no way decreased his caution. He remained for the time being below the diaphragm, not wishing to disturb in any way the heart he could feel beating just above it; but he was able to find without effort a large artery in the abdomen which offered no more resistance to penetration than had any other part of the human organism thus far. He discovered, to his intense satisfaction, that he could draw enough oxygen from the red cells (he did not think of them by color, since he had not yet seen them) to supply his needs without seriously diminishing the quantity that passed through the vessel. He checked this fact very carefully. His whole attitude in the present exploration was utterly different from that which had directed his actions within the body of the shark, for he had come to look upon Robert in the light of a permanent companion during his stay on the earth, and his present actions were ruled by a law of his kind so ancient and so rigid as to assume almost the proportions of an instinct.
Do nothing that can harm your host!
Chapter III. OUT OF PLAY
Do nothing that can harm your host! For the majority of the Hunter's kind even the desire to break that law never existed, since they lived on terms of the warmest friendship with the beings whose bodies harbored theirs. The few individuals who proved to be exceptions were regarded with the liveliest horror and detestation by their fellows. It was one of these whom the Hunter had been pursuing at the time of his crash on the earth; and that being, he well knew, must still be found-if only to protect this native race from the inroads of the irresponsible creature.
Do nothing that can harm your host! From the moment of the Hunter's arrival the swarming white cells in the boy's healthy blood had been aroused. He had avoided the most serious contacts with them up to now by keeping clear of the interiors of blood vessels, though there were enough of them wandering free in the lymphatics and connective tissue to be a nuisance. His body cells were not naturally immune to their powers of absorption, and only by constant evasive action had he been able to avoid serious damage to himself. He knew this could not go on indefinitely; for one thing, he must occasionally direct his attention to other matters, and, for another, the continuation of such a misunderstanding, whether he persevered in evasive action or began to fight back, would mean an increase in the number of white cells and probably some sort of illness to his host. Therefore, the leucocytes must be pacified. His race had, of course, worked out long since a general technique for solving this problem, but care still had to be taken in individual cases-particularly unfamiliar ones. By a trial-and-error process carried out with as much speed as was practical, the Hunter determined the nature of the chemical clue by which the white cells differentiated invading organisms from legitimate members of the human body; and after prolonged and still extremely careful effort he exposed every one of his cells to sources of the appropriate chemicals in his host's blood stream. A few molecules of the desired substance were absorbed on the surface of each cell, and this, to his relief, proved to be sufficient. The leucocytes ceased to bother him, and he could use the larger blood vessels safely as avenues of exploration for his questing pseudopoda.
Do nothing that can harm your host! He needed food as well as oxygen. He could have consumed with relish and satisfaction any of the various forms of tissue surrounding him, but the law made selection necessary. There were certainly intruding organisms in this body-besides himself-and they were the logical food source, for by consuming them he would be eliminating their menace to his host and thereby helping to earn his keep. Identifying them would be easy; anything a leukocyte attacked would be legitimate prey for the Hunter. Probably the local microbes would not keep him fed for long, small as his needs were, and it would also be necessary to tap the digestive tract at some point; but that need not cause damage, unless a slightly increased appetite on the part of the host came under that heading.
For many hours the cautious exploration and adjustment continued. The Hunter felt his host awaken and resume activity, but he made no effort to look outside. He had one problem which must be carefully and accurately solved; and, although his dodging the attentions of thousands of leucocytes at once, as he had done for a time, may seem evidence to the contrary, his power of attention was limited. That had simply been an automatic action roughly comparable to a man's carrying on a conversation while he climbs stairs.
Filaments of the Hunter's flesh, far finer than human neurons, gradually formed an all-inclusive network ' throughout Bob's body from head to toe; and through those threads the Hunter came gradually to know the purpose and customary uses of every muscle, gland, and sense organ in that body. Throughout this period most of his mass remained in the abdominal cavity, and it was more than seventy-two hours after his first intrusion that he felt secure enough in his position to pay attention once more to outside affairs.
As he had done with the shark, he began to fill the spaces between the boy's retinal cells with his own body substance. He was actually able to make better use of Bob's eyes than their proper owner could, for the human eyes see in maximum detail only those objects whose images fall within an area of retina less than a millimeter across. The Hunter could use the whole area on which the lens focused with reasonable sharpness, which was decidedly larger. In consequence, he could examine with Bob's eyes objects at which the boy was not looking directly. This was likely to be a help, since many of the things in which the hidden watcher was most interested would be too commonplace to the human being to attract his direct gaze.
The Hunter could hear dimly even within the human body, but he found it helpful to establish direct physical contact with the bones of the middle ear. Thus, hearing as well as seeing better than his host, he felt ready to investigate the planet on which chance had marooned him and his quarry. There was no further reason-he thought- for delay in searching for and destroying the criminal of his own race now free on the world. He began to look and listen.
The search itself he had never regarded as more than a routine job. He had had similar problems before. He had expected to look around from the vantage point of Bob's body until he found t
he others, leave and eliminate his opponent by standard means-regardless of the fact that all his equipment was at the bottom of the sea. He had had, in short, a viewpoint which is excusable in a space navigator but not in a detective: he had been regarding a planet as a small object and thinking his search was practically over when he had narrowed it down to one world.
He was rudely jolted out of this attitude as he took his first look around since meeting Bob Kinnaird. The picture that fell on their common retinas was that of the interior of a cylindrical object vaguely suggestive of his own space ship. It was filled with several rows of seats, most of them occupied by human beings. Beside the watcher was a window through which Bob was looking at the moment; and the suspicion that had entered the Hunter's mind was instantly confirmed by the view through that window. They were on board an aircraft, traveling at a considerable altitude with a speed and in a direction which the alien was in no position to estimate. Start looking for his quarry? He must first look for the right continent!
The flight lasted for several hours and had probably already consumed several. The Hunter quickly gave up the attempt to memorize landmarks over which they passed. One or two of them did stick in his mind and might give a clue to direction if he could ever identify them later; but he put little trust in this possibility. He must keep track of time rather than position, and when he was more familiar with human ways find out where his host had been at the time of his own intrusion.
The view itself, though, was interesting, even if the landmarks were lacking. It was a beautiful planet, from his alien viewpoint; mountains and plains, rivers and lakes, forests and prairies were all visible at various times, now clearly through miles of crystal atmosphere and now in glimpses between billowing clouds of water vapor. The machine he rode was also worthy of attention; from Robert's window he could not see very much of it, but that little told him a great deal. A portion of a metal wing was visible, bearing attachments which evidently contained engines, as rapidly rotating air foils were visible ahead of them. Since the craft was presumably symmetrical, the Hunter decided there must be at least four of these engines. He could not tell with accuracy how much of then- energy was wasted in heat and sound-for one thing, he suspected that the cabin in which he rode was quite effectively sound-proofed. The machine as a whole, however, suggested that this race had evidently attained a considerable degree of mechanical advancement, and a new idea blossomed from that: might he not attempt to enter into communication with this being which was his host and secure its active co-operation in his, search? It was a point well worth considering.
There was plenty of time for thought before the airplane gradually began to descend. The Hunter could not see directly ahead, and it happened that they entered a solid cloud layer almost immediately, so he was unable to get any idea of their destination until just before the landing. He chalked up another point for the race: they either had senses he lacked, or were very competent and ingenious instrument makers, for the descent through the clouds was as smooth as any other part of the flight.
After some time spent letting down through the gray murk, the machine broke out into clear air. As it banked into a wide turn the Hunter saw a large city built around a great, crowded harbor; then the faint drone of the engines increased in pitch, a large double wheel appeared below one of the nacelles, and the craft glided easily downward to contact with a faint jar a broad, hard-surfaced runway located on a point of land across the harbor from the largest buildings.
As Robert disembarked he glanced back at the airplane, so the Hunter was better able to form an estimate of its size and construction details. He had no idea of the power developed by the four bulky engines, and could not, therefore, guess at the speed; but he could see the quivering in the air above the huge nacelles that told of hot metal within and knew at least that they were not the phoenix converters used by his race and its allies. Whatever they were, though, it had already become evident that the machine could put a very respectable fraction of the planet's circumference behind it without having to descend for fuel.
After alighting from the airplane the boy went through the usual formalities incident to reclaiming his baggage, took a bus around the harbor to the city, walked about for a while, and visited a movie. This the Hunter also enjoyed; his vision persistence involved about the same tune lapse as the human eye, so he saw the show as a movie rather than a set of separate pictures. It was still daylight when they emerged and walked back to the bus station, where Bob reclaimed the luggage he had checked, then they boarded another bus.
This turned out to be quite a long ride; the vehicle took them far outside the city and through several smaller towns, and the sun was almost down when it finally left them by the roadside.
A smaller side road, with broad, well-kept lawns on either side, led off up a gentle slope, and at the top of this slope was a large, sprawling building, or group of buildingsthe Hunter was not sure which from his viewpoint. Robert picked up his bags and walked up the hill toward this structure, and the alien began to hope that the journey had ended, for the time being at least. He was far enough from his quarry already. As it turned out, his hopes for once were fulfilled.
To the boy the return to school, assignment to a room, and meeting with old acquaintances were by now familiar, but to the Hunter every activity and everything he saw and heard were of absorbing interest. He had no intention, even yet, of making a really detailed study of the human race, but some subconscious guide was beginning to warn him that his mission was not to be quite the routine job he had expected and that he might possibly have use for all the earthly knowledge he could get. He didn't know it yet, but he had come to the best possible place for knowledge.
He looked and listened almost feverishly as Bob went to his room, unpacked, and then wandered about the dormitory meeting friends from former terms. He found himself trying almost constantly to connect the flood of spoken words with their meanings; but it was difficult, since most of the conversation concerned events of the vacation just past, and the words usually lacked visible referents. He did learn the personal names of some of the beings, however, among them that of his host.
He decided, after an hour or two, that it would be best to turn his full attention to the language problem. There was nothing whatever at the moment that he could do about his own mission, and if he understood the speech around him he might be able to learn when his host was to return to the place where they had met. Until he did return, the Hunter was simply out of play-he could do nothing at all toward locating and eliminating his quarry.
With this idea finally settled upon he spent Robert's sleeping hours organizing the few words he had learned, trying to deduce some grammatical rules, and developing a definite campaign for learning more as quickly as possible. It may seem odd that one who was so completely unable to control his own comings and goings should dream of planning anything, but the extra effective width of his vision angle must be remembered. He was to some extent able to determine what he saw and therefore felt that he should decide what to look for.
It would have been far simpler, if he could only control his host's movements in some way or other, or interpret and influence the multitudinous reactions that went on in his nervous system. He had controlled the perit, of course, but not directly; the little creature had been trained to respond to twinges administered directly to its muscles, as a horse is trained to respond to the pressure of the reins. The Hunter's people used the perils to perform actions which their own semi-liquid bodies lacked the strength to do, and which were too delicate for their intelligent hosts to perform-or which had to be performed in places which had brought the Hunter to earth.
Unfortunately for this line of thought Robert Kinnaird was not a perit and could not be treated as one. There was no hope, at present, of influencing his actions at all, and any such hope in the future must rest on appeals to the boy's reason rather than on force. At the moment the Hunter was rather in the position of a movie spectator who w
ants to change the plot of the film he is seeing.
Classes began the day after their arrival. Their purpose was at once obvious to the unlisted pupil though the subjects were frequently obscure. The boy's course included, among other subjects, English, physics, Latin, and French; and of those four, oddly enough, physics proved most helpful in teaching the Hunter the English language. The reason is not too difficult to understand.
While the Hunter was not a scientist, he knew something of science-one can hardly operate a machine like a space ship without having some notion of what makes it work. The elementary principles of the physical sciences are the same anywhere, and while the drawing conventions accepted by the authors of Bob's textbooks differed from those of the Hunter's people, the diagrams were still understandable. Since the diagrams were usually accompanied by written explanations, they were clues to the meanings of a great many words.
The connection between spoken and written English was also cleared up one day in a physics class, when the instructor used a heavily lettered diagram to explain a problem in mechanics. The unseen watcher suddenly understood the connection between letter and sound and within a few days was able to visualize the written form of any new word he heard-allowing, of course, for the spelling irregularities that are the curse of the English language.
The learning process was one which automatically increased its speed as time went on, for the more words the Hunter knew, the more he could guess at from the context in which he met them. By the beginning of November, two months after the opening of school, the alien's vocabulary had the size, though not the precise content, of an intelligent ten-year-old's. He had a rather excessive store of scientific terms and many blanks where less specialized words should have been. Also, the meanings he attached to many terms were the strictly scientific ones- for example, he thought work meant "force times distance," and only that.