The Hawkinsite spoke again. “What do you want?”

  And this time Drake answered. He said, “The answer to certain ques­tions.”

  “With a gun in your hand? I would not humor your discourtesy so far.”

  “You would not merely be humoring me. You might be saving your own life.”

  “That would be a matter of considerable indifference to me, under the circumstances. I am sorry, Mr. Smollett, that the duties toward a guest are so badly understood on Earth.”

  “You are no guest of mine, Dr. Tholan,” said Drake. “You entered my house on false pretenses. You had some reason for it, some way you had planned of using me to further your own purposes. I have no compunction in reversing the process.”

  “You had better shoot. It will save time.”

  “You are convinced that you will answer no questions? That, in itself, is suspicious. It seems that you consider certain answers to be more important than your life.”

  “I consider the principles of courtesy to be very important. You, as an Earthman, may not understand.”

  “Perhaps not. But I, as an Earthman, understand one thing.” Drake had jumped forward, faster than Rose could cry out, faster than the Hawkinsite could connect his limbs. When he sprang backward, the flexible hose of Harg Tholan’s cyanide cylinder was in his hand. At the corner of the Hawkinsite’s wide mouth, where the hose had once been affixed, a droplet of colorless liquid oozed sluggishly from a break in the rough skin, and slowly solidified into a brown jellylike globule, as it oxidized.

  Drake yanked at the hose and the cylinder jerked free. He plunged home the knob that controlled the needle valve at the head of the cylinder and the small hissing ceased.

  “I doubt,” said Drake, “that enough will have escaped to endanger us. I hope, however, that you realize what will happen to you now, if you do not answer the questions I am going to ask you--and answer them in such a way that I am convinced you are being truthful.”

  “Give me back my cylinder,” said the Hawkinsite, slowly, “If not, it will be necessary for me to attack you and then it will be necessary for you to kill me.”

  Drake stepped back. “Not at all. Attack me and I shoot your legs from under you. You will lose them; all four, if necessary, but you will still live, in a horrible way. You will live to die of cyanide lack. It would be a most uncomfortable death. I am only an Earthman and I can’t appreciate its true horrors, but you can, can’t you?”

  The Hawkinsite’s mouth was open and something within quivered yellow-green. Rose wanted to throw up. She wanted to scream. Give him bock the cylinder, Drake! But nothing would come. She couldn’t even turn her head.

  Drake said, “You have about an hour, I think, before the effects are irreversible. Talk quickly, Dr. Tholan, and you will have your cylinder back.”

  “And after that--” said the Hawkinsite.

  “After that, what does it matter to you? Even if I kill you then, it will be a clean death; not cyanide lack.”

  Something seemed to pass out of the Hawkinsite. His voice grew guttural and his words blurred as though he no longer had the energy to keep his English perfect. He said, “What are your questions?” and as he spoke, his eyes followed the cylinder in Drake’s hand.

  Drake swung it deliberately, tantalizingly, and the creature’s eyes followed --followed--

  Drake said, “What are your theories concerning the Inhibition Death? Why did you really come to Earth? What is your interest in the Missing Persons Bureau?”

  Rose found herself waiting in breathless anxiety. These were the questions she would like to have asked, too. Not in this manner, perhaps, but in Drake’s job, kindness and humanity had to take second place to necessity.

  She repeated that to herself several times in an effort to counteract the fact that she found herself loathing Drake for what he was doing to Dr. Tholan.

  The Hawkinsite said, “The proper answer would take more than the hour I have left me. You have bitterly shamed me by forcing me to talk under duress. On my own planet, you could not have done so under any circum­stances. It is only here, on this revolting planet, that I can be deprived of cyanide.”

  “You are wasting your hour, Dr. Tholan.”

  “I would have told you this eventually, Mr. Smollett. I needed your help. It is why I came here.”

  “You are still not answering my questions.”

  “I will answer them now. For years, in addition to my regular scientific work, I have been privately investigating the cells of my patients suffering from Inhibition Death. I have been forced to use the utmost secrecy and to work without assistance, since the methods I used to investigate the bodies of my patients were frowned upon by my people. Your society would have similar feelings against human vivisection, for instance. For this reason, I could not present the results I obtained to my fellow physicians until I had verified my theories here on Earth.”

  “What are your theories?” demanded Drake. The feverishness had re­turned to his eyes.

  “It became more and more obvious to me as I proceeded with my studies that the entire direction of research into the Inhibition Death was wrong. Physically, there was no solution to its mystery. The Inhibition Death is entirely a disease of the mind.”

  Rose interrupted, “Surely, Dr. Tholan, it isn’t psychosomatic.”

  A thin, gray translucent film had passed over the Hawkinsite’s eyes. He no longer looked at them. He said, “No, Mrs. Smollett, it is not psychoso­matic. It is a true disease of the mind; a mental infection. My patients had double minds. Beyond and beneath the one that obviously belonged to them, there was evidence of another one--an alien mind. I worked with Inhibition Death patients of other races than my own, and the same could be found. In short, there are not five intelligences in the Galaxy, but six. And the sixth is parasitic.”

  Rose said, “This is wild--impossible! You must be mistaken, Dr. Tholan.”

  “I am not mistaken. Until I came to Earth, I thought I might be. But my stay at the Institute and my researches at the Missing Persons Bureau con­vinced me that is not so. What is so impossible about the concept of a parasitic intelligence? Intelligences like these would not leave fossil remains, nor even leave artifacts--if their only function is to derive nourishment somehow from the mental activities of other creatures. One can imagine such a parasite, through the course of millions of years, perhaps, losing all portions of its physical being but that which remains necessary, just as a tapeworm, among your Earthly physical parasites, eventually lost all its func­tions but the single one of reproduction. In the case of the parasitic intelli­gence, all physical attributes would eventually be lost. It would become nothing but pure mind, living in some mental fashion we cannot conceive of on the minds of others. Particularly on the minds of Earthmen.”

  Rose said, “Why particularly Earthmen?”

  Drake simply stood apart, intent, asking no further questions. He was content, apparently, to let the Hawkinsite speak.

  “Have you not surmised that the sixth intelligence is a native of Earth? Mankind from the beginning has lived with it, has adapted to it, is uncon­scious of it. It is why the higher species of terrestrial animals, including man, do not grow after maturity and, eventually, die what is called natural death. It is the result of this universal parasitic infestation. It is why you sleep and dream, since it is then that the parasitic mind must feed and then that you are a little more conscious of it, perhaps. It is why the terrestrial mind alone of the intelligences is so subject to instability. Where else in the Galaxy are found split personalities and other such manifestations? After all, even now there must be occasional human minds which are visibly harmed by the presence of the parasite.

  “Somehow, these parasitic minds could traverse space. They had no phys­ical limitations. They could drift between the stars in what would corre­spond to a state of hibernation. Why the first ones did it, I don’t know; probably no one will ever know. But once those
first discovered the presence of intelligence on other planets in the Galaxy, there was a small, steady stream of parasitic intelligences making their way through space. We of the outer worlds must have been a gourmet’s dish for them or they would have never struggled so hard to get to us. I imagine many must have failed to make the trip, but it must have been worth the effort to those who suc­ceeded.

  “But you see, we of the other worlds had not lived with these parasites for millions of years, as man and his ancestors had. We had not adapted our­selves to it. Our weak strains had not been killed off gradually through hundreds of generations until only the resistants were left. So, where Earthmen could survive the infection for decades with little harm, we others die a quick death within a year.”

  “And is that why the incidence has increased since interstellar travel between Earth and the other planets has begun?”

  “Yes.” For a moment there was silence, and then the Hawkinsite said with a sudden access of energy, “Give me back my cylinder. You have your answer.”

  Drake said, coolly, “What about the Missing Persons Bureau?” He was swinging the cylinder again; but now the Hawkinsite did not follow its movements. The gray translucent film on his eyes had deepened and Rose wondered whether that was simply an expression of weariness or an example of the changes induced by cyanide lack.

  The Hawkinsite said, “As we are not well adapted to the intelligence that infests man, neither is it well adapted to us. It can live on us--it even prefers to, apparently--but it cannot reproduce with ourselves alone as the source of its life. The Inhibition Death is therefore not directly contagious among our people.”

  Rose looked at him with growing horror. “What are you implying, Dr. Tholan?”

  “The Earthman remains the prime host for the parasite. An Earthman may infect one of us if he remains among us. But the parasite, once it is located in an intelligence of the outer worlds, must somehow return to an Earthman, if it expects to reproduce. Before interstellar travel, this was possible only by a re-passage of space and therefore the incidence of infec­tion remained infinitesimal. Now we are infected and reinfected as the parasites return to Earth and come back to us via the mind of Earthmen who travel through space.”

  Rose said faintly, “And the missing persons--”

  “Are the intermediate hosts. The exact process by which it is done, I, of course, do not know. The masculine terrestrial mind seems better suited for their purposes. You’ll remember that at the Institute I was told that the life expectancy of the average human male is three years less than that of the average female. Once reproduction has been taken care of, the infested male leaves, by spaceship, for the outer worlds. He disappears.”

  “But this is impossible,” insisted Rose. “What you say implies that the parasite mind can control the actions of its host! This cannot be, or we of Earth would have noticed their presence.”

  “The control, Mrs. Smollett, may be very subtle, and may, moreover, be exerted only during the period of active reproduction. I simply point to your Missing Persons Bureau. Why do the young men disappear? You have eco­nomic and psychological explanations, but they are not sufficient. --But I am quite ill now and cannot speak much longer. I have only this to say. In the mental parasite, your people and mine have a common enemy. Earthmen, too, need not die involuntarily, except for its presence. I thought that if I found myself unable to return to my own world with my informa­tion because of the unorthodox methods I used to obtain it, I might bring it to the authorities on Earth, and ask their help in stamping out this menace. Imagine my pleasure when I found that the husband of one of the biologists at the Institute was a member of one of Earth’s most important investigat­ing bodies. Naturally, I did what I could to be made a guest at his home in order that I might deal with him privately; convince him of the terrible truth; utilize his position to help in the attack on the parasites.

  “This is, of course, now impossible. I cannot blame you too far. As Earthmen, you cannot be expected to understand the psychology of my people. Nevertheless, you must understand this. I can have no further deal­ing with either of you. I could not even bear to remain any longer on Earth.”

  Drake said, “Then you alone, of all your people, have any knowledge of this theory of yours.”

  “I atone.”

  Drake held out the cylinder. “Your cyanide, Dr. Tholan.”

  The Hawkinsite groped for it eagerly. His supple fingers manipulated the hose and the needle valve with the utmost delicacy. In the space of ten seconds, he had it in place and was inhaling the gas in huge breaths. His eyes were growing clear and transparent.

  Drake waited until the Hawkinsite breathings had subsided to normal, and then, without expression, he raised his needle-gun and fired. Rose screamed. The Hawkinsite remained standing. His four lower limbs were incapable of buckling, but his head lolled and from his suddenly flaccid mouth, the cyanide hose fell, disregarded. Once again, Drake closed the needle valve and now he tossed the cylinder aside and stood there somberly, looking at the dead creature. There was no external mark to show that he had been killed. The needle-gun’s pellet, thinner than the needle which gave the gun its name, entered the body noiselessly and easily, and exploded with devastating effect only within the abdominal cavity.

  Rose ran from the room, still screaming. Drake pursued her, seized her arm. She heard the hard, flat sounds of his palm against her face without feeling them and subsided into little bubbling sobs.

  Drake said, “I told you to have nothing to do with this. Now what do you think you’ll do?”

  She said, “Let me go. I want to leave. I want to go away.”

  “Because of something it was my job to do? You heard what the creature was saying. Do you suppose I could allow him to return to his world and spread those lies? They would believe him. And what do you think would happen then? Can you imagine what an interstellar war might be like? They would imagine they would have to kill us all to stop the disease.”

  With an effort that seemed to turn her inside out, Rose steadied. She looked firmly into Drake’s eyes and said, “What Dr. Tholan said were no lies and no mistakes, Drake,”

  “Oh, come now, you’re hysterical. You need sleep.”

  “I know what he said is so because the Security Commission knows all about that same theory, and knows it to be true.”

  “Why do you say such a preposterous thing?”

  “Because you yourself let that slip twice.”

  Drake said, “Sit down.” She did so, and he stood there, looking curiously at her. “So I have given myself away twice, have I? You’ve had a busy day of detection, my dear. You have facets you keep well hidden.” He sat down and crossed his legs.

  Rose thought, yes, she had had a busy day. She could see the electric clock on the kitchen wall from where she sat; it was more than two hours past midnight. Harg Tholan had entered their house thirty-five hours before and now he lay murdered in the spare bedroom.

  Drake said, “Well, aren’t you going to tell me where I pulled my two boners?”

  “You turned white when Harg Tholan referred to me as a charming hostess. Hostess has a double meaning, you know, Drake. A host is one who harbors a parasite.”

  “Number one,” said Drake. “What’s number two?”

  “That’s something you did before Harg Tholan entered the house. I’ve been trying to remember it for hours. Do you remember, Drake? You spoke about how unpleasant it was for Hawkinsites to associate with Earthmen, and I said Harg Tholan was a doctor and had to. I asked you if you thought that human doctors particularly enjoyed going to the tropics, or letting infected mosquitoes bite them. Do you remember how upset you became?”

  Drake laughed. “I had no idea I was so transparent. Mosquitoes are hosts for the malaria and yellow fever parasites.” He sighed. “I’ve done my best to keep you out of this. I tried to keep the Hawkinsite away. I tried threatening you. Now there’s nothing left but to tell you the tru
th. I must, because only the truth--or death--will keep you quiet. And I don’t want to kill you.”

  She shrank back in her chair, eyes wide.

  Drake said, “The Commission knows the truth. It does us no good. We can only do all in our power to prevent the other worlds from finding out.”

  “But the truth can’t be held down forever! Harg Tholan found out. You’ve killed him, but another extraterrestrial will repeat the same discovery--over and over again. You can’t kill them all.”

  “We know that, too,” agreed Drake. “We have no choice.”

  “Why?” cried Rose. “Harg Tholan gave you the solution. He made no suggestions or threats of war between worlds. He suggested that we combine with the other intelligences and help to wipe out the parasite. And we can! If we, in common with all the others, put every scrap of effort into it--”

  “You mean we can trust him? Does he speak for his government or for the other races?”

  “Can we dare to refuse the risk?”

  Drake said, “You don’t understand.” He reached toward her and took one of her cold, unresisting hands between both of his. He went on, “I may seem silly trying to teach you anything about your specialty, but I want you to hear me out. Harg Tholan was right. Man and his prehistoric ancestors have been living with this parasitic intelligence for uncounted ages; certainly for a much longer period than we have been truly Homo sapiens. In that interval, we have not only become adapted to it, we have become dependent upon it. It is no longer a case of parasitism. It is a case of mutual coopera­tion. You biologists have a name for it.”

  She tore her hand away. “What are you talking about? Symbiosis?”

  “Exactly. We have a disease of our own, remember. It is a reverse disease; one of unrestrained growth. We’ve mentioned it already as a contrast to the Inhibition Death. Well, what is the cause of cancer? How long have biolo­gists, physiologists, biochemists and all the others been working on it? How much success have they had with it? Why? Can’t you answer that for yourself now?”