William Tenn - Venus and the Seven Sexes

“After the matrimonial convention, when the chain is established, each sex’s germ-cells are stimulated into meiosis. The germ-cell divides into seven gametes, six of them with cilia and the seventh secreted either inside or outside the Plookh, depending on the sex.”

“What’s this chain?”

“The chain of reproduction. The usually stated order is srob (aquatic form), mlenb (amphibian), tkan (winged), guur (plant-like), flin (a burrower), blap (tree-dweller). And, of course, the chain proceeds in a circle as: srob, mlenb, tkan, guur, flin, blap, srob, mlenb, tkan, guur, flin, blap, srob—”

Hogan Shlestertrap had grasped his head with his hands and was rocking it slowly back and forth. “Starts with srobs and ends with blaps,” he said, almost inaudibly. “And I’m a—”

“Srobb,” I corrected him timidly. “And blapp. And it doesn’t necessarily start with one and end with another. A birth may be initiated anywhere along the chain of a family, just so it passes through all sexes—thus acquiring the necessary chromosomes for a fertilized zygote.”

“All right! Please get back to chromosomes and sanity. You just had a germ-cell dividing—a srob’s, say—into seven gametes instead of a decent two like all other logical species use.”

“Well, so far as our weak minds can compass it, this is the chromosome pattern worked out by Gogarty and his assistant, Wolfsten, after prolonged microscopic examination. Gogarty warned my ancestor, nzred fanobrel, that it was only an approximation. According to this analysis, the germ-cell of a given sex has forty-nine chromosomes, seven each of Types A, B, C, D, E , F, six of Type G and one of Type H —the last, Type H, being the sex determinant. Six mobile gametes are formed through meiosis—each containing an identical group of seven chromosomes of Types A through G —and a seventh or stationary gamete containing chromosomes A, B, C, D, E, F, and H. This last Gogarty called the female or H gamete, since it never leaves the body of the Plookh until the fully fertilized cell of forty-nine chromosomes—or seven gametes—is formed, and since it determines sex. The sex, of course, is that of the Plookh in whose body it is stationary.”

“Of course,” Shlestertrap murmured and conjugated long and thoughtfully with the bottle.

“It has to be, since that is the only H chromosome in the final zygote. But you know that for yourself. In fact, operating with a human intelligence, you have probably anticipated me and already extrapolated the whole process from the few facts I have mentioned.”

Moisture gathered at the top of our civilizer’s head and rolled down his face in the quaintest of patterns. “I understand you,” he admitted, “and of course I’ve already figured out the whole thing. But just to make it clear in your own mind, don’t you think you might as well continue?”

I thanked him for his unfailing human courtesy. “Now, if it is a srob with whom we start our chain, it will transmit one of its six mobile gametes to a mlenb where the gamete will unite with one of the mlenb’s A through G cells, forming what Gogarty called a double-gamete or pre-zygote. This pre-zygote will contain seven pairs of A through G chromosomes, and, in the body of the tkan—next in the chain—it will unite with a tkan mobile gamete forming a triple-gamete with seven triplets of A through G chromosomes. It proceeds successively through the rest of the sexes capturing a seven-chromosome gamete each time, until, when it is transmitted to the blap, it contains forty-two chromosomes—six A’s, six B’s and so on through to six G ’s. At this point, the sextuple gamete loses its cilia; and unites, in the blap, with the stationary H gamete to form a forty-nine chromosome zygote which, of course, is of the blap sex. The egg is laid and it hatches shortly into a baby blap, guarded—when at all possible—and taught in ten days all that its parent can teach it about surviving as a blap Plookh. At the end of ten days, the half-grown blap goes its way to feed and escape from danger by itself. At the end of a hundred days, it is ready to join a family and reproduce in full adulthood.

“The chain may be said to begin at any point; but it always travels in the same direction. Thus a flin will transmit the original seven-chromosome gamete to the blap of his chain where it will become a double-gamete; the blap will transmit the double-gamete to the srob, who will make it a triple-gamete; eventually, in this case, the process will come to fruition on the vines of the guur resulting in a guur zygote. Was not Gogarty clever, even for a human? He suggested, by the way, that it was possible we were not really a seven-sexed creature, but seven distinct species living in a reproductive symbiosis.”

“Gogarty was a damned genius! Hey, wait a minute! Srob, mlenb, tkan, guur, flin, blap—that’s only six!”

At last we were getting to the interesting part. “Quite so. I am a representative of the seventh sex—a nzred.”

“A nzred, huh? What do you do?”

“I coordinate.”

One of the robots scurried in in answer to his yell. He ordered it to bring a case of these bottles of whiskey and to place it near his chair. He also ordered it to stand by, prepared for emergencies.

This was all very enjoyable. My information was creating even more of a sensation than that described by my ancestor, nzred fanobrel. It is not often that we Plookhh have an opportunity to sit thus with an animal of a different species and provide intellectual instead of gustatory diversion.

“He coordinates! Maybe they can use a good expediter or dispatcher?”

“I fulfill all of those functions. Chiefly, however, I coordinate. You see, a mlenb is primarily interested in winning the affections of a likely srob and finding a tkan whom he can love. A tkan merely courts a mlenb and is attracted to a good guur. I am responsible for getting a complete chain of these individuals in operation, a chain of compatibility where perfect amity runs in a complete circle—a chain which will produce offspring of maximum variability. Then, after the matrimonial convention, when the chain is established, each sex begins to secrete its original germ with the full forty-nine chromosomes. A busy time for nzredd! I must make certain that all germ-cells are developing at a uniform rate—each sex attempts to fertilize seven H gametes in the course of a cycle—and the destruction of one individual in the middle of the cycle means the complete disarrangement of a family except for the gametes which he has already passed on in multiple state. Replacement of an eaten individual with another of the same sex, the remainder of whose family has been wiped out, is occasionally possible with the aid of the chief of his sex.”

“I can see they keep you hopping,” Hogan Shlestertrap observed. “But how does a nzred get born if you aren’t in this chain thing?”

“A nzred is outside a chain, yet inside it as well. The six sexes which transmit gametes to each other directly form a chain; a chain plus a nzred equals a family. The nzred, in his personal reproductive functions, fits himself at any point in the chain which the exigencies of the situation seem to demand. He may receive the sextuple super-gamete from the tkan and transmit the original single gamete to the guur, he may be between the flin and blap, the blap and srob, whatever is required. For example, in the Season of Twelve Hurricanes, the tkan is unable to fly and pursue his reproductive relationship with the guur wherever it has rooted itself: the nzred fills what would be a gap in the chain. This is rather difficult to express in an unfamiliar language—the biologists of the first expedition found this process slightly more complicated than the mitoses of the fertilized Plookh cell, but—”