To the right of their line of travel was an area that, except for the thorns, looked more like a bamboo thicket than a lilac bush-the plants were separate stalks thrusting individually from the ground a few inches apart and shooting straight up. Like nearly everything produced in the first year or two of the island laboratory's existence, they possessed horns-iron-hard, needle-sharp specimens an inch and a half long on the main stems and only a trifle shorter on the stubby, horizontal, thin-leafed branches that commenced within a foot of the ground. The object that had attracted the Hunter's attention lay at the edge of this patch of vegetation. He could not make it out exactly, since its image was well off the optical axis of Bob's eye lenses, but he saw enough to arouse his curiosity.
"Bob! What is that?" The boy turned his eyes in the direction indicated, and both recognized the pile of white objects instantly-Bob because he had seen such things before and the Hunter from his general knowledge of biology. Bob wormed his way over to it as quickly as he could, and then lay prone looking at the skeleton which lay partly in and partly out of the thicket of straight-growing shrubs.
"So that's what became of Tip," the boy said at last slowly. "Hunter, can you offer a guess at what killed him?"
The Hunter made no answer at first, but looked carefully over the bones. As nearly as he could tell from his memory of the dog's structure they were arranged naturally- even to the claws and the tiny bone that seemed to correspond to the hyoid in his host's tongue. The animal had apparently died in one piece and been undisturbed afterward.
"He doesn't seem to have been eaten, at least by any larger or medium-sized creature of his own general type," the Hunter advanced cautiously.
"That seems true enough. Ants, or something of the sort, could have cleaned the bones like that after he died, but we have none on this island that could have killed him first. Are you thinking what I am?"
"I'm no mind reader, though I've learned to know you well enough to predict your actions occasionally. I think I know what you mean, though. I admit that it is perfectly possible that the dog was killed and eaten by our friend after being ridden here from some part of the shore. I would point out, however, that I can see no reason for killing the dog here of all places; there could hardly be a less suitable place on the island for finding a new host. Also, the dog had flesh enough to last for weeks. Why should he stay here long enough to consume it all?"
"Panic. He might have thought you were right on his trail, and picked this for a hiding place." The Hunter had not expected such a prompt answer to what he had meant as a rhetorical question, but he had to admit that Bob's suggestion was distinctly possible. The boy had another idea before he could say any more.
"Hunter, couldn't you tell by examining these bones whether the flesh had been taken by one of your people or not? I'll hold one as long as you like, if you want to go over it thoroughly."
"Do that, please. Something might be learned."
Bob gingerly picked a femur out of the collection. The neighboring bones tended to adhere slightly; there were apparently traces of cartilage remaining in the joints. The boy held it firmly in his clenched hand, knowing how the Hunter would make his examination. It was the first time he had an opportunity actually to see part of his guest's body, but he nobly resisted the temptation to open his hand. As a matter of fact, it would have done him no good: the Hunter used exploratory filaments fine enough to reach through the pores in his host's skin and much too thin to be visible. The search took several minutes.
"All right; you may put it down."
"Did you find anything?"
"A little. Such evidence as there is suggests that our friend was not responsible. The marrow in the bone had decayed normally, as did blood and other organic material in the bone tubelets. It is hard to see why our friend should have remained long enough to consume the greater part of the available flesh but leave what I found. The evidence indicates that your suggestion of ants is a very likely one."
"But not certain?"
"Of course not. It would be a most remarkable coincidence, but if you wish to believe that our arrival scared the fugitive away before he had time to finish his meal, I could not disprove it."
"Where would he have gone?"
"/ am not defending this wild supposition. However, if we must dispose of it, then his most likely goal would be your body, and I can guarantee he has not tried that!"
"Maybe he guessed you were here." Bob could be irritating at times, the Hunter reflected, much as he liked the youngster.
"Maybe he did. Maybe he's flowing at top speed through this thicket to get away." The Hunter's voice would have been weary had it been audible. Bob smiled and headed downhill once more, but the detective noticed that he kept to the edge of the stand of plants he had mentioned. However improbable an idea might be, Bob was not going to leave it unchecked if checking were so easy!
"You have a friend waiting for you, you know."
"I know. This won't take long."
"Oh. I thought you might be planning to go entirely around this patch of spikes. I was going to point out that, if all the things we have been saying are true, you might also be walking into what I believe you call a booby trap. You don't have to be logical, but you might at least be consistent."
"Did I ever read those words?" countered Bob. "You'd better start teaching me English. If you'd listen, you'd realize we were coming to the creek, which should lead to the path we used the other day, which should lead to my house. I know it's not straight, but it's sure." He stopped talking and jumped as a small animal sprang out from almost underfoot and vanished into the thicket. "Darned rats. If there were a few million more of you, Hunter, you could do this island-not to mention a lot of other places-considerable good. They're too smart for any other animal small enough to catch 'em."
"In places like that I suppose you mean," the other supplemented. "We have similar pests where I come from. We work on them when they get too troublesome, or when there is nothing better to do. I'm afraid there is a rather serious problem facing us just now. It begins to look as though we would have to employ your idea, at least to check young Teroa, in the next few nights."
Bob nodded thoughtfully and occupied his mind with details of this possibility as they traveled. The bush had opened out a little on their left, and it was possible to walk erect again as they approached the creek. The stream was already two or three feet wide, even this far up the hill; it had its origin in a spring surprisingly close to the top of the ridge, which occasionally dried up during prolonged rainless spells. These, as it happened, were rare. The creek itself had cut deep into the soil without spreading very wide; the roots of the thick vegetation held the steep and sometimes undercut banks. In many places saplings that had been unable to meet the fierce competition for soil had fallen over so that they made bridges across the stream or moss-draped inclines sloping from the banks into the water. Occasionally larger trees had fallen and damned the creek, making little dark pools with tiny waterfalls at their lower ends.
Such a pool was located a few yards above the spot where Bob and the Hunter reached the stream. The tree which formed it had fallen years before, and most of its few branches had fallen away or become buried in the soft soil as rain, insects, and worms did their bit. The water escaped from the pool on the side from which Bob and the Hunter had approached and had deeply undercut the bank at that point, and the buried branches-perhaps-aggravated the situation. There was no warning. Bob started to turn downstream at what should have been a perfectly safe distance from the bank even if he had had a thought of danger in his mind. As his weight came on his right foot the ground suddenly gave way and let him down, and something struck his ankle a heavy blow. He reacted rapidly enough to catch himself with his hands and the other leg as his right knee disappeared, then he paused to recover his wits.