Barely an inch long, the hungry leech undulated through the water, a thin brown ribbon. Reacting to vibrations and shadows, it located a prey’s chemical plume and followed it to its source.

It attached its front sucker on the smooth skin of its victim. Thick mucus and suction held it steady while three crescent jaws cut a Y-shaped incision. Applying blood-thinning and numbing secretions, it fed.

After 20 minutes it detached itself and drifted away, engorged with blood.

• • •

Terrence Hanover IV waded slowly toward the shore of Potter’s Pond, his empty dip-net propped over his shoulder. He had caught a few minnows and tadpoles, tickled them with his finger to see them squirm. Then he’d everted the net and freed them.

He wasn’t really interested in minnows, just needed some alone time. Terry felt sad, and his head hurt.

Sports-freak parents had raised him to adore football. All football, all year, counting Australian and Canadian variants. They bought him his own Packers jersey and a little helmet, which he quickly outgrew.

But he wasn’t even allowed to play Pop Warner football; he might hurt somebody. Normal ten-year-olds don’t stand six feet two, or weigh 240 pounds.

• • •

A leech can live for six months on a single blood-meal. Its digestive system doesn’t dissolve its food all at once. Instead, it dissolves the high-protein meal one amino acid at a time, a slow method for a long protein. Specialized gut bacteria aid the process.

Those gut bugs themselves are targets of still smaller viruses known as “phages.” Phages invade the bacterium and its nucleus, genetically reprogramming them to make more phages before the cell itself disintegrates. Phages are also used in labs to transport foreign genes into complex organisms.

Some bacteria can destroy phages in self-defense. Genetically loaded fragments of dead phage are expelled as the germ purges itself. Surrounding fluids become phage soup.

“Lateral gene transfer,” the movement of genetic material from one organism into another, is common among microbes – penetration without sex. Once genes from one bug are incorporated into another, they become part of the host’s own genetic machinery.

Eight per cent of humans’ own genes arrived via the assimilation of viruses into the human genome.

Sometimes an external gene package is immediately lethal to the host. Sometimes it’s neutral, neither helpful nor harmful.

Sometimes new genes create new traits. Survival traits.

• • •

In a few months, the leech mated. A hermaphrodite with both ovaries and testes, it exchanged favors with another leech that much resembled itself. It soon laid an egg sac protected by a tough mucus capsule. The eggs had formed from special cells, in ovaries bathed in phage debris. Some had assimilated fragments of Terry’s DNA, diverse byproducts of the Phage Wars’ collateral damage.

• • •

“I’m sorry to ask you to come down to the office,” the doctor said, “but it’s better we discuss this in person.”

“Is Terry all right?” asked Mrs. Hanover. “Has something happened?”

“I should back up a bit,” said the doctor. “Twenty years ago, after the Corporate Tax Moratorium, human gene engineering was essentially deregulated. Mm-hmm. They thought big corporations could afford to advance biomedical science on their own.“But it was still very expensive just to conduct the research, so the usual human trials were cut short, and Terry’s procedure came on line pretty rapidly. Still expensive, of course.

“As you’re doubtless aware, most families lacked your, ah, fiscal resources. Few participants could afford the procedure when it did become publically available. It wasn’t profitable, and since last year, it’s no longer marketed.

“Unfortunately, delayed effects show up slowly in such a small group of subjects.”

“Side-effects? You told us Terry would be extra healthy, and that he would grow up to be tall. Muscles. Athletic. The ‘Stature Package,’ right?”

“It appears that the gene complex we engineered into the embryo was, ah, epigenetically unstable. As it bypassed the usual growth regulators, it also erased limitations on growth. It has happened in every case. Our tests show Terry will...”

“Epi-whatever!” she interrupted, annoyed by his technobabble. “He seems very healthy to us.”

“Mrs. Hanover, he’s going to keep growing. He won’t stop. He won’t become truly gigantic, because of two things. Although he retains most body proportions as he grows, physics come into play. Soon, even his sturdy legs will not support his weight. It will even be hard to lift his chest to breathe if he’s lying down.

“But his brain, only his brain, will stop growing after reaching its natural size, due to a different gene set — one we overlooked. It can’t oversee increased hormone regulation, miles of extra nerves. He’ll become demented, then paralyzed.

“We’ve even tried surgical pituitary removal. Nothing works. I’m so sorry, Mrs. Hanover.”

• • •

The total disappearance of fish and frogs from Potter’s Pond was puzzling. Its usual waterfowl population fled. And now a swimmer had vanished from view in waist-deep water, reappearing as a shriveled soggy mass by the time help arrived.

Various observers reported glistening black forms moving in the pond, large enough to leave a wake. “The Loch Potter Monsters,” went the joke.

Then aquatic animal life also disappeared along the system of lakes into which Potter’s drained. Boats were overturned, fishermen lost.

Gradually the joking stopped.

Jon Hauxwell, MD, is a retired family physician who grew up in Stockton and lives outside Hays.