Chapter 16

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.”