"There's one objection remaining," he said at last. "Would our friend know what you have just mentioned -that a blow on the nose does not necessarily cause bleeding? After all, he hasn't had a lifetime of human experience like you."
"I even thought of that." Bob was triumphant. "How could he be the sort of thing he is, and be where he is, without knowing? He just would have to know what causes a nosebleed and whether it's necessary or not. I haven't asked the Hunter yet, but how else could it be? How about it, Hunter?" He awaited the answer, at first with complete confidence, then with mounting doubt as the alien considered the wording of his response.
"I should say that you are quite right," the Hunter replied at last. "I had not considered that possibility before, and there was the chance that our friend had not, either; but even in that case he would certainly have seen that there was no danger in stopping the bleeding at any tune. The boys who were fighting kept it up long after you were applying nose pressure and cold water and other odd remedies. You score first, Bob; I am willing to forget those two."
Bob repeated this to Dr. Seever, who received the information with a grim nod.
"I have an elimination candidate also," he answered. "Tell me, Bob, didn't you say your attention had been attracted to Ken Malmstrom yesterday?"
"Yes, a little. He didn't work so hard as usual on the boat and he seemed quieter, but I figured it was because Charlie was going away."
"And today?"
"I don't know. I haven't seen him since school."
"I'll bet you haven't," said Seever dryly. "You shouldn't have seen him in school, either. He had a temperature of a hundred and three right afterward, when he finally decided to tell his parents he wasn't feeling well."
"What?"
"Your friend is down with malaria, and I'd like to know where in blazes he picked it up." The doctor glared as though Bob had been personally responsible.
"Well, there are mosquitoes on the island," pointed out that young man, uneasy under the glare.
"I know, though we keep "em down pretty well. But where did they get it? I keep track of the people who leave this island or visit it; the crew of the tanker-some of 'em -come ashore for short periods. They're out, I'm sure; I know their medical histories. You've been away long enough to get anything and come back, but you can't be the one, unless the Hunter has been preserving the disease in your blood for fun."
"Is it a virus disease? The Hunter wants to know."
"No. It's caused by a flagellate-a protozoan. Here"-the doctor found a book with appropriate microphotographs -"look at these, Hunter, and see if anything like 'em were or are still in Robert's blood."
The answer was prompt.
"They are not now, and I really do not recall all the types of micro-organisms I destroyed months ago. You should recall whether or not he has ever shown symptoms of the disease. Your own blood contains many creatures that bear a superficial resemblance to that inert state illustrated, as I noticed yesterday, but with only those pictures to go by I could not say whether they were identical or not. I should be glad to help you more actively, if my problem were not so pressing."
"Bob," said the doctor when this had been transmitted, "if you don't hang onto that friend of yours after he finishes his job, and go to medical school yourself, you'll be a traitor to civilization. However, that's not germane to either of our problems. I don't like what you implied, Hunter, but I won't deny its possibility without further tests. That's my job. The point I started to make is that your friend cannot be inside Malmstrom's body; everything you've just said about nosebleed goes double for germ disease. You can't suspect anyone for not getting sick, and our fugitive must know it."
There was a silence of general agreement after this statement. This appeared ready to lengthen indefinitely; Bob broke it with the remark, "That leaves Norman and Hugh of our original top-priority list. I would have voted for Norm without question this afternoon; now I'm not so sure."
"Why not?"
The boy repeated the Hunter's words of a few minutes before and the doctor shrugged them off.
"If you have your own ideas and won't tell us, Hunter, you can only expect us to act on ours," he said.
"That is just what I want," pointed out the detective. "You both have a tendency to regard me as all-knowing in this matter. That is not true. We are on your world, among your people. I will develop and test my ideas, with your help when necessary, but I want you to do the same with yours. You won't, if you let yourselves be influenced to any great extent by my opinions."
"A good point," agreed Seever. "All right, then, my present idea is the same as Bob's-that you make a personal examination, with the least practical delay, of Master Norman Hay. The only other candidate on our list always did seem the least likely. If this were a detective story, I suppose I'd be advising you to work on him. Robert, here, can take you up to a point near Hay's home as he planned before, and you can make the check tonight."
"You have forgotten your own argument-that I should be ready to do something about it if I find our friend there," responded the detective. "It seems to me that the testing of drugs had better go on, while you, Robert, and I keep our eyes open for evidence such as turned up today."
"I'm darned if I'll spread a malaria epidemic just for that," said the doctor. "Still, I suppose you're right. We'll try another drug-and don't tell me you like the taste; it's too expensive for candy." He set to work. "By the way"- he looked up from loading the gun-"wasn't Norman one of the stowaways a while back? How would that fit in?"
"He was," Bob replied, "but I couldn't tell you how it fits. The whole idea was Red's, and he backed out at the last minute from what I hear."
Seever applied the hypo thoughtfully. "Maybe that thing was with Teroa for a while and shifted to Hay. They must have slept at least once fairly close to each other while they were hiding on the ship."
"Why should he change?"
"He might have thought that Hay's chances of getting ashore were better. Remember Norman wanted to see the museum on Tahiti."
"That would mean that it had been with Charlie long enough to learn to understand English; and it would also mean that Norm's interest in biology had nothing funny about it, since it developed before he was invaded," pointed out Bob. The doctor was forced to concede this.
"All right," he said, "it was just an idea. I never claimed to have evidence for it. It's a pity we can't find the drug we're looking for. This malaria business would give me an excuse to administer it wholesale, if I had enough, which I probably wouldn't."
"You're no closer to finding it so far," reported the Hunter at that point. The doctor grimaced.
"We probably won't, either. Your structure is too different from that of any earthly creature, I suppose. I wish you would give us some of your own ideas; this seems too haphazard to me."
"I discussed my ideas with Bob a long time ago," the Hunter replied. "I have been following them. Unfortunately, they lead to such a wide field of possibilities that I am afraid to start testing them. I'd rather exhaust your field first."
"What, in Heaven's name, did you discuss with him that you haven't mentioned to me?" Seever asked the boy. "This is a fine time to learn that you have more clues."