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,

but I 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 what would have been its

normal size. Instead of filling the skull completely, it shared the

space with a green, amorphous shape. This was ridged somewhat like a

brain, but the green shape had still darker nodules and extensions.

Lea took her scalpel and gently 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 unusual organ it has, called the pseudova. Now that I have seen

this growth in the magter's skull, I can think of a positive

parallel. The fly _Drepanosiphum_ also had a large green organ, only

it fills half of the body cavity instead of the head. Its identity

puzzled biologists for years, and they had a number of complex

theories to explain it. Finally someone managed to dissect and

examine it. The pseudova turned out to be a living plant, a

yeastlike growth that helps with the green-fly's digestion. It

produces enzymes that enable the fly to digest the great amounts

of sugar it gets from plant juice."

"That's not unusual," Brion said, puzzled. "Termites and human

beings are a couple of other creatures whose digestion is helped

by internal flora. What's the difference in the green-fly?"

"Reproduction, mainly. All the other gut-living plants have to enter

the host and establish themselves as outsiders, permitted to remain

as long as they are useful. The green-fly and its yeast plant have a

permanent symbiotic relationship that is essential to the existence

of both. The plant spores appear in many places throughout the fly's

body--but they are _always_ in the germ cells. Every egg cell has

some, and every egg that grows to maturity is infected with the

plant spores. The continuation of the symbiosis is unbroken and

guaranteed."

"Do you think those green spheres in the magter's blood cells could

be the same kind of thing?" Brion asked.

"I'm sure of it," Lea said. "It must be the same process. There are

probably green spheres throughout the magters' bodies, spores or

offspring of those things in their brains. Enough will find their

way to the germ cells to make sure that every young magter is

infected at birth. While the child is growing, so is the symbiote.

Probably a lot faster, since it seems to be a simpler organism.

I imagine it is well established in the brain pan within the first

six months of the infant's life."

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

"I'm only guessing now, but there is plenty of evidence that gives

us an idea of its function. I'm willing to bet that the symbiote

itself is not a simple organism, it's probably an amalgam of plant

and animal like most of the other creatures on Dis. The thing is

just too complex to have developed since mankind has been on this

planet. The magter must have caught the symbiotic infection eating

some Disan animal. The symbiote lived and flourished in its new

environment, well protected by a bony skull in a long-lived host.

In exchange for food, oxygen and comfort, the brain-symbiote must

generate hormones and enzymes that enable the magter to survive.

Some of these might aid digestion, enabling the magter to eat any

plant or animal life they can lay their hands on. The symbiote might

produce sugars, scavenge the blood of toxins--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 the symbiote, but it didn't matter to race survival until

now. Did you notice that the magter's brain is no smaller than

normal?"

"It must be--or how else could that brain-symbiote fit in inside

the skull with it?" Brion said.

"If the magter's total brain were smaller in volume than normal

it could fit into the remaining space in the cranial hollow. But

the brain is full-sized--it is just that part of it is missing,

absorbed by the symbiote."

"The frontal lobes," Brion said with sudden realization.

"This hellish growth has performed a prefrontal lobotomy!"

"It's done even more than that," Lea said, separating the

convolutions of the gray matter with her scalpel to uncover a green

filament beneath. "These tendrils penetrate further back into the

brain, but always remain in the cerebrum. The cerebellum appears to

be untouched. Apparently just the higher functions of mankind have

been interfered with, selectively. Destruction of the frontal lobes

made the magter creatures without emotions or ability for really

abstract thought. Apparently they survived better without these.

There must have been some horrible failures before the right balance

was struck. The final product is a man-plant-animal symbiote that is

admirably adapted for survival on this disaster world. No emotions

to cause complications or desires that might interfere with pure

survival. Complete ruthlessness--mankind has always been strong on

this anyway, so it didn't take much of a push."

"The other Disans, like Ulv here, managed to survive without turning

into such a creature. So why was it necessary for the magter to go

so far?"

"Nothing is necessary in evolution, you know that," Lea said. "Many

variations are possible, and all the better ones continue. You might

say that Ulv's people survive, but the magter survive better. If

offworld contact hadn't been re-established, I imagine that the

magter would slowly have become the dominant race. Only they won't

have the chance now. It looks as though they have succeeded in

destroying both races with their suicidal urge."

"That's the part that doesn't make sense," Brion said. "The magter

have survived and climbed right to the top of the evolutionary heap

here. Yet they are suicidal. How does it happen they haven't been

wiped out before this?"

"Individually, they have been aggressive to the point of suicide.

They will attack anything and everything with the same savage lack

of emotion. Luckily there are no bigger animals on this planet. So

where they have died as individuals, their utter ruthlessness has

guaranteed their survival as a group. Now they are faced with a

problem that is too big for their half-destroyed minds to handle.

Their personal policy has become their planetary policy--and that's

never a very smart thing. They are like men with knives who have

killed all the men who were only armed with stones. Now they are

facing men with guns, and they are going to keep charging and

fighting until they are all dead.

"It's a perfect case of the utter impartiality of the forces of

evolution. Men infected by this Disan life form were the dominant

creatures on this planet. The creature in the magters' brains was a

true symbiote then, giving something and receiving something, making

a union of symbiotes where all were stronger together than any could

be separately. Now this is changed. The magter brain cannot

understand the concept of racial death, in a situation where it must

understand to be able to survive. Therefore the brain-creature is no

longer a symbiote but a parasite."

"And as a parasite it must be destroyed!" Brion broke in. "We're not

fighting shadows any more," he exulted. "We've found the enemy--and

it's not the magter at all. Just a sort of glorified tapeworm that

is too stupid to know when it is killing itself off. Does it have

a brain--can it think?"

"I doubt it very much," Lea said. "A brain would be of absolutely no

use to it. So even if it originally possessed reasoning powers they

would be gone by now. Symbiotes or parasites that live internally

like this always degenerate to an absolute minimum of functions."

"Tell me about it. What is this thing?" Ulv broke in, prodding the

soft form of the brain-symbiote. He had heard all their excited talk

but had not understood a word.

"Explain it to him, will you, Lea, as best you can," Brion said,

looking at her, and he realized how exhausted she was. "And sit down

while you do it; you're long overdue for a rest. I'm going to try--"

He broke off when he looked at his watch.

It was after four in the afternoon--less than eight hours to go.

What was he to do? Enthusiasm faded as he realized that only half of

the problem was solved. The bombs would drop on schedule unless the

Nyjorders could understand the significance of this discovery. Even

if they understood, would it make any difference to them? The threat

of the hidden cobalt bombs would not be changed.

With this thought came the guilty realization that he had forgotten

completely about Telt's death. Even before he contacted the Nyjord

fleet he must tell Hys and his rebel army what had happened to Telt

and his sand car. Also about the radioactive traces. They couldn't

be checked against the records now to see how important they might

be, but Hys might make another raid on the strength of the

suspicion. This call wouldn't take long, then he would be free

to tackle Professor-Commander Krafft.

Carefully setting the transmitter on the frequency of the rebel

army, he sent out a call to Hys. There was no answer. When he

switched to receive all he heard was static.

There was always a chance the set was broken. He quickly twisted the

transmitter to the frequency of his personal radio, then whistled in

the microphone. The received signal was so loud that it hurt his

ears. He tried 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."

It came as a shock that it was Professor-Commander Krafft who answered.

"I'm sorry, Brion, but it's impossible to talk to Hys. We are

monitoring his frequency and your call was relayed to me. Hys and

his rebels lifted ship about half an hour ago, and are already on

the way back to Nyjord. Are you ready to leave now? It will soon

become dangerous to make any landings. Even now I will have to ask

for volunteers to get you out of there."

Hys and the rebel army gone! Brion assimilated the thought. He had

been thrown off balance when he realized he was talking to Krafft.

"If they're gone--well, then there's nothing I can do about it," he

said. "I was going to call you, so I can talk to you now. Listen and

try to understand. You must cancel the bombing. I've found out about

the magter, found what causes their mental aberration. If we can

correct that, we can stop them from attacking Nyjord--"

"Can they be corrected by midnight tonight?" Krafft broke in. He was

abrupt and sounded almost angry. Even saints get tired.

"No, of course not." Brion frowned at the microphone, realizing the

talk was going all wrong, but not knowing how to remedy it. "But it

won't take too long. I have evidence here that will convince you

that what I say is the truth."

"I believe you without seeing it, Brion." The trace of anger was

gone from Krafft's voice now, and it was heavy with fatigue and

defeat. "I'll admit 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 way to tackle the problem of Dis. We have

made a lot of mistakes, and in making them we have run out of time.

I'm afraid that is the only fact that is relevant now. The bombs

fall at twelve, and even then they may drop too late. A ship is

already on its way from Nyjord with my replacement. I exceeded my

authority by running a day past the maximum the technicians gave me.

I realize now I was gambling the life of my own world in the vain

hope I could save Dis. They can't be saved. They're dead. 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 fact will not be changed by anything you say. All the

offworlders--other than your party--are gone. I'm sending a ship

down now to pick you up. As soon as that ship lifts I am going to

drop the first bombs. Now--tell me where you are so they can come

for you."

"Don't threaten me, Krafft!" Brion shook his fist at the radio in an

excess of anger. "You're a killer and a world destroyer--don't try

to make yourself out as anything else. I have the knowledge to avert

this slaughter and you won't listen to me. And I know where the

cobalt bombs are--in the magter tower that Hys raided last night.

Get those bombs and there is no need to drop any of your own!"

"I'm sorry, Brion. I appreciate what you're trying to do, but at the

same time I know the futility of it. I'm not going to accuse you of

lying, 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 know where the bombs are. The best-kept magter secret."

"I don't know for sure, but there is a very good chance it is so,"

Brion said, trying to repair his defenses. "Telt made readings, he

had other records of radioactivity in this same magter keep--proof

that something is there. But Telt is dead now, the records

destroyed. Don't you see--" He broke off, realizing how vague and

unprovable his case was. This was defeat.

The radio was silent, with just the hum of the carrier wave as

Krafft waited for him to continue. When Brion did speak his voice

was empty of all hope.

"Send your ship down," he said tiredly. "We're in a building that

belonged to the Light Metals Trust, Ltd., a big warehouse of some

kind. I don't know the address here, but I'm sure you have someone

there who can find it. We'll be waiting for you. You win, Krafft."

He turned off the radio.