Sense of Obligation

by Harry Harrison

  XVI

  Ulv joined them as they looked down at the exposed brain of the magter.The thing was so clearly evident that even Ulv noticed it.

  "I have seen dead animals and my people dead with their heads open, butI have never seen anything like that before," he said.

  "What is it?" Brion asked.

  "The invader, the alien you were looking for," Lea told him.

  The magter's brain was only two-thirds of its normal size. Instead offilling the skull completely, it shared the space with a green,amorphous shape. This was ridged somewhat like a brain, but the greenshape had still darker nodules and extensions. Lea took her scalpel andgently prodded the dark moist mass.

  "It reminds me very much of something that I've seen before on Earth,"she said. "The green-fly--_Drepanosiphum platanoides_--and an unusualorgan it has, called the pseudova. Now that I have seen this growth inthe magter's skull I can think of a positive parallel. The fly_Drepanosiphum_ also has a large green organ, only it fills half of thebody cavity instead of the head. Its identity puzzled biologists foryears, and they had a number of complex theories to explain it away.Finally someone managed to dissect and examine it. The pseudova turnedout to be a living plant, a yeastlike growth that helps with thegreen-fly's digestion. It produces enzymes that enable the fly to digestthe great amounts of sugar it gets from plant juice."

  "That's not unusual," Brion said, puzzled. "Termites and human beingsare a couple of other creatures whose digestion is helped by internalflora. What's the difference in the green-fly?"

  "Reproduction, mainly. All the other gut-living plants have to enter thehost and establish themselves as outsiders, permitted to remain as longas they are useful. The green-fly and its yeast plant have a permanentsymbiotic relationship that is essential to the existence of both. Theplant spores appear in many places throughout the fly's body--but theyare _always_ in the germ cells. Every egg cell has some, and every eggthat grows to maturity is infected with the plant spores. Thecontinuation of the symbiosis is unbroken and guaranteed.

  "Do you think those green spheres in the magter's blood cells could bethe same kind of thing?" Brion asked.

  "I'm sure of it," Lea said. "It must be the same process. There areprobably green spheres throughout the magters' bodies, spores oroffspring of those things in their brains. Enough will find their way tothe germ cells to make sure that every young magter is infected atbirth. While the child is growing--so is the symbiote. Probably a lotfaster since it seems to be a simpler organism. I imagine it is wellestablished in the brain pan within the first six months of the infant'slife."

  "But why?" Brion asked. "What does it do?"

  "I'm only guessing now, but there is plenty of evidence that gives us anidea of its function. I'm willing to bet that the symbiote itself is nota simple organism, it's probably an amalgam of plant and animal likemost of the other creatures on Dis. The thing is just too complex tohave developed since mankind has been on this planet. The magter musthave caught the symbiotic infection by eating some Disan animal. Thesymbiote lived and flourished in its new environment. Well protected bya bony skull in a long-lived host. In exchange for food, oxygen andcomfort, the brain-symbiote must generate hormones and enzymes thatenable the magter to survive. Some of these might aid digestion,enabling the magter to eat any plant or animal life they can lay theirhands on. The symbiote might produce sugars, scavenge the blood oftoxins--there are so many things it could do. Things it must have done,since the magter are obviously the dominant life form on this planet.They paid a high price for their symbiote, but it didn't really matterto race-survival until now. Did you notice that the magter's brain is nosmaller than normal?"

  "It must be--or how else could that brain-symbiote fit in inside theskull with it?" Brion said.

  "If the magter's total brain were smaller in volume than normal, itcould fit into the remaining space in the cranial hollow. But the brainis full-sized--it is just that part of it is missing, absorbed by thesymbiote."

  "The frontal lobes," Brion said with sudden realization. "This hellishgrowth has performed a prefrontal lobotomy!"

  * * * * *

  "It's done even more than that," Lea said, separating the convolutionsof the gray matter with her scalpel to uncover a green filament beneath."These tendrils penetrate farther back into the brain, but always remainin the cerebrum. The cerebellum appears to be untouched. Apparently justthe higher functions of mankind have been interfered with, selectively.Destruction of the frontal lobes made the magter creatures withoutemotions or ability for really abstract thought. Apparently theysurvived better without these. There must have been some horriblefailures before the right balance was struck. The final product is aman-plant-animal symbiote that is admirably adapted for survival onthis disaster world. No emotions to cause complications or desires thatmight interfere with pure survival. Complete ruthlessness--mankind hasalways been strong on this anyway, so it didn't take much of a push."

  "The other Disans, like Ulv here, managed to survive without turninginto such a creature. So why was it necessary for the magter to go sofar?"

  "Nothing is necessary in evolution, you know that," Lea said. "Manyvariations are possible and all the better ones continue. You might saythat Ulv's people survive, but the magter survive better. If offworldcontact hadn't been re-established, I imagine that the magter wouldslowly have become the dominant race. Only they won't have the chancenow. It looks as though they have succeeded in destroying both raceswith their suicidal urge."

  "That's the part that doesn't make sense," Brion said. "The magter havesurvived and climbed right to the top of the evolutionary heap here. Yetthey are suicidal. How come they haven't been wiped out before this?"

  "Individually they have been aggressive to the point of suicide. Theywill attack anything and everything with the same savage lack ofemotion. Luckily there are no bigger animals on this planet. So wherethey have died as individuals, their utter ruthlessness has guaranteedtheir survival as a group. Now they are faced with a problem that is toobig for their half-destroyed minds to handle. Their personal policy hasbecome their planetary policy--and that's never a very smart thing. Theyare like men with knives who have killed all the men who were only armedwith stones. Now they are facing men with guns and they are going tokeep charging and fighting until they are all dead."

  "It's a perfect case of the utter impartiality of the forces ofevolution. Men infected by this Disan life form were the dominantcreatures on this planet. The creature in the magters' brains was a truesymbiote then, giving something and receiving something. Making a unionof symbiotes where all were stronger together than any could beseparately. Now this is changed. The magter brain cannot understand theconcept of racial death, in a situation where it must understand to beable to survive. Therefore, the brain-creature is no longer a symbiotebut a parasite."

  "And as a parasite it must be destroyed!" Brion broke in. "We're notfighting shadows any more," he exulted. "We've found the enemy--and it'snot the magter at all. Just a sort of glorified tapeworm that is toostupid to know when it is killing itself off. Does it have a brain--canit think?"

  "I doubt it very much," Lea said. "A brain would be of absolutely no useto it. So even if it originally possessed reasoning powers they would begone by now. Symbiotes or parasites that live internally like thisalways degenerate to an absolute minimum of functions...."

  "Tell me about it? What is this thing?" Ulv broke in, producing thesoft form of the brain-symbiote. He had heard all their excited talk buthad not understood a word.

  "Explain it to him, will you Lea, as best you can," Brion said, lookingat her and realized how exhausted she was. "And sit down while you doit, you're long overdue for a rest. I'm going to try--" He broke offwhen he looked at his watch.

  * * * * *

  It was after four in the afternoon--less than eight hours to go. Whatwas he to do? Enthusiasm faded as he realized that only half of theproblem was solved. T
he bombs would drop on schedule unless theNyjorders could understand the significance of this discovery. Even ifthey understood--would it make any difference to them? The threat of thehidden cobalt bombs would not be changed.

  With this thought came the guilty realization that he had forgottencompletely about Telt's death. Even before he contacted the Nyjord fleethe must tell Hys and his rebel army what had happened to Telt and hissandcar. Also about the radioactive traces. They couldn't be checkedagainst the records now to see how important they might be, but Hysmight make another raid on the strength of the suspicion. This callwouldn't take long, then he would be free to tackle Professor-CommanderKrafft.

  Carefully setting the transmitter on the frequency of the rebel army, hesent out a call to Hys. There was no answer.

  There was always a chance the set was broken. He quickly twisted thetransmitter to the frequency of his personal radio, then whistled in themicrophone. The received signal was so loud that it hurt his ears. Hetried to call Hys again, and was relieved to get a response this time.

  "Brion Brandd here, can you read me? I want to talk to Hys at once."

  Shockingly, it was Professor-Commander Krafft who answered.

  "I'm sorry Brion, but it's impossible to talk to Hys. We are monitoringhis frequency and your call was relayed to me. Hys and his rebels liftedship about a half an hour ago, and are already on the way back toNyjord. Are you ready to leave now? It will soon become dangerous tomake any landings. Even now I will have to ask for volunteers to get youout of there."

  Hys and the rebel army gone. Brion assimilated the thought at the samemoment he realized he was talking to Krafft. He was thrown off balance,not prepared for the encounter.

  "If they're gone--well, then there's nothing I can do about it," Brionsaid. "I was going to call you, so I can talk to you now. Listen and tryto understand. You must cancel the bombing. I've found out about themagter, found what causes their mental aberration. If we can correctthat, we can stop them from attacking Nyjord--"

  "Can they be corrected by midnight tonight?" Krafft broke in. He wasabrupt and sounded annoyed. Even saints get tired.

  "No, of course not." Brion frowned at the microphone, realizing the talkwas going all wrong, but not knowing how to fix it. "But it won't taketoo long. I have evidence here that will convince you that what I say isthe truth."

  "I believe you without seeing it, Brion." The trace of anger was gonefrom Krafft's voice now and it was heavy with fatigue and defeat. "I'lladmit you are probably right. A little while ago I admitted to Hys, too,that he was probably right in his original estimation of the correct wayto tackle the problem of Dis. We have made a lot of mistakes, and inmaking them we have run out of time. I'm afraid that is the only factthat is relevant now. The bombs fall at twelve and even then they maydrop too late. A ship is already on its way from Nyjord with myreplacement. I exceeded my authority by running a day past the maximumthe technicians gave me. I realize now I was gambling the life of my ownworld in the vain hope I could save Dis. They can't be saved. They'redead. I won't hear any more about it."

  "You must listen--"

  "I must destroy the planet below me, that is what I must do. That factwill not be changed by anything you say. All the offworlders--other thanyour party--are gone. I'm sending a ship down now to pick you up. Assoon as that ship lifts I am going to drop the first bombs. Now--tell mewhere you are so they can come for you."

  "Don't threaten me, Krafft!" Brion shook his fist at the radio in anexcess of anger. "You're a killer and a world destroyer, don't try andmake yourself out as anything else. I have the knowledge to avert thisslaughter and you won't listen to me. And I know where the cobalt bombsare--in the magter tower that Hys raided last night. Get those bombs andthere is no need to drop any of your own!"

  "I'm sorry, Brion. I appreciate what you're trying to do, yet at thesame time I know the futility of it. I'm not going to accuse you oflying, but do you realize how thin your evidence sounds from this end?First a dramatic discovery of the cause of the magters' intransigency.Then, when that had no results, you suddenly remember that you knowwhere the bombs are. The best kept magter secret...."

  "I don't know for sure, but there is a very good chance," Brion said,trying to repair his defenses. "Telt made readings, he had other recordsof radioactivity in this same magter keep. Proof that something isthere. But Telt is dead now, the records destroyed. Don't you see--" Hebroke off, realizing how vague and unprovable his case was. This wasdefeat.

  The radio was silent, with just the hum of the carrier wave as Krafftwaited for him to continue. When Brion did speak his voice was empty ofall hope.

  "Send your ship down," he said tiredly. "We're in a building thatbelonged to the Light Metals Trust Ltd., a big warehouse of some kind. Idon't know the address here, but I'm sure you have someone there whocan find it. We'll be waiting for you."

  "You win Krafft."

  He turned off the radio.