Mr. Conklin was delighted and so was I, and that is the title that he used, and the one that I am now using.

 First appearance-Amazing Stories, March 1961, under the title "Playboy and the Slime God." Copyright ©, 1961, by Ziff-Davis Publishing Company.

"But these are two species," said Captain Garm, peering closely at the creatures that had been brought up from the planet below. His optic organs adjusted focus to maximum sharpness, bulging outwards as they did so. The color patch above them gleamed in quick flashes.

Botax felt warmly comfortable to be following color-changes once again, after months in a spy cell on the planet, trying to make sense out of the modulated sound waves emitted by the natives. Communication by flash was almost like being home in the far-off Perseus arm of the Galaxy. "Not two species," he said, "but two forms of one species."

"Nonsense, they look quite different. Vaguely Perse-like, thank the Entity, and not as disgusting in appearance as so many out-forms are. Reasonable shape, recognizable limbs. But no color-patch. Can they speak?"

"Yes, Captain Garm," Botax indulged in a discreetly disapproving prismatic interlude. "The details are in my report. These creatures form sound waves by way of throat and mouth, something like complicated coughing. I have learned to do it myself." He was quietly proud. "It is very difficult."

"It must be stomach-turning. Well, that accounts for their flat, unextensible eyes. Not to speak by color makes eyes largely useless. Meanwhile, how can you insist these are a single species? The one on the left is smaller and has longer tendrils, or whatever it is, and seems differently proportioned. It bulges where this other does not. Are they alive?"

"Alive but not at the moment conscious, Captain. They have been psycho-treated to repress fright in order that they might be studied easily."

"But are they worth study? We are behind our schedule and have at least five worlds of greater moment than this one to check and explore. Maintaining a Time-stasis unit is expensive and I would like to return them and go on-"

But Botax's moist spindly body was fairly vibrating with anxiety. His tubular tongue flicked out and curved up and over his flat nose, while his eyes sucked inward. His splayed three-fingered hand made a gesture of negation as his speech went almost entirely into the deep red.

"Entity save us, Captain, for no world is of greater moment to us than this one. We may be facing a supreme crisis. These creatures could be the most dangerous life-forms in the Galaxy, Captain, just because there are two forms."

"I don't follow you."

"Captain, it has been my job to study this planet, and it has been most difficult, for it is unique. It is so unique that I can scarcely comprehend its facets. For instance, almost all life on the planet consists of species in two forms. There are no words to describe it, no concepts even. I can only speak of them as first form and second form. If I may use their sounds, the little one is called 'female,' and the big one, here, 'male,' so the creatures themselves are aware of the difference."

Garm winced, "What a disgusting means of communication."

"And, Captain, in order to bring forth young, the two forms must cooperate."

The Captain, who had bent forward to examine the specimens closely with an expression compounded of interest and revulsion, straightened at once. "Cooperate? What nonsense is this? There is no more fundamental attribute of life than that each living creature bring forth its young in innermost communication with itself. What else makes life worth living?"

"The one form does bring forth life but the other form must cooperate."

"How?"

"That has been difficult to determine. It is something very private and in my search through the available forms of literature I could find no exact and explicit description. But I have been able to make reasonable deductions."

Garm shook his head. "Ridiculous. Budding is the holiest, most private function in the world. On tens of thousands of worlds it is the same. As the great photo-bard, Levuline, said, 'In budding-time, in budding time, in sweet, delightful budding time; when-' "

"Captain, you don't understand. This cooperation between forms brings about somehow (and I am not certain exactly how) a mixture and recombination of genes. It is a device by which in every generation, new combinations of characteristics are brought into existence. Variations are multiplied; mutated genes hastened into expression almost at once where under the usual budding system, millennia might pass first."

"Are you trying to tell me that the genes from one individual can be combined with those of another? Do you know how completely ridiculous that is in the light of all the principles of cellular physiology?"

"It must be so," said Botax nervously under the other's pop-eyed glare. "Evolution is hastened. This planet is a riot of species. There are supposed to be a million and a quarter different species of creatures."

"A dozen and a quarter more likely. Don't accept too completely what you read in the native literature."

"I've seen dozens of radically different species myself in just a small area. I tell you, Captain, give these creatures a short space of time and they will mutate into intellects powerful enough to overtake us and rule the Galaxy."

"Prove that this cooperation you speak of exists, Investigator, and I shall consider your contentions. If you cannot, I shall dismiss all your fancies as ridiculous and we will move on."

"I can prove it." Botax's color-flashes turned intensely yellow-green. "The creatures of this world are unique in another way. They foresee advances they have not yet made, probably as a consequence of their belief in rapid change which, after all, they constantly witness. They therefore indulge in a type of literature involving the space-travel they have never developed. I have translated their term for the literature as 'science-fiction.' Now I have dealt in my readings almost exclusively with science-fiction, for there I thought, in their dreams and fancies, they would expose themselves and their danger to us. And it was from that science-fiction that I deduced the method of their inter-form cooperation."

"How did you do that?"

"There is a periodical on this world which sometimes publishes science-fiction which is, however, devoted almost entirely to the various aspects of the cooperation. It does not speak entirely freely, which is annoying, but persists in merely hinting. Its name as nearly as I can put it into flashes is 'Recreationlad.' The creature in charge, I deduce, is interested in nothing but inter-form cooperation and searches for it everywhere with a systematic and scientific intensity that has roused my awe. He has found instances of cooperation described in science-fiction and I let material in his periodical guide me. From the stories he instanced I have learned how to bring it about.

"And Captain, I beg of you, when the cooperation is accomplished and the young are brought forth before your eyes, give orders not to leave an atom of this world in existence."

"Well," said Captain Garm, wearily, "bring them into full consciousness and do what you must do quickly."

Marge Skidmore was suddenly completely aware of her surroundings. She remembered very clearly the elevated station at the beginning of twilight. It had been almost empty, one man standing near her, another at the other end of the platform. The approaching train had just made itself known as a faint rumble in the distance.

There had then come the flash, a sense of turning inside out, the half-seen vision of a spindly creature, dripping mucus, a rushing upward, and now- "Oh, God," she said, shuddering. "It's still here. And there's another one, too."