Infected Page 6

Including the host.

The host’s mites lived their entire, brief, skin-gobbling lives without ever leaving his body. In their incessant feeding frenzy, some of the mites came across the seeds — which looked suspiciously similar to flakes of

human skin. The mites gobbled up the minute seeds; just another mouthful in an endless and bountiful banquet of dead flesh.

The mite’s digestive system hammered at the seed’s outer coat. Protein-digesting enzymes, called proteases, ate away at the membrane, breaking it down, weakening it. The membrane ruptured in several places but did not dissolve completely. Still intact, the seed pa.s.sed through the mite’s digestive tract.

And that’s where it all began, really — in a microscopic pile of bug s.h.i.+t. The temperature hovered around seventy degrees much of the time and often reached eighty degrees or more with suitable cover. The seed needed such temperatures. It also needed certain measures of salinity and humidity, which the host’s skin unwittingly provided. These conditions triggered receptor cells, turning the seeds “on,” so to speak, and preparing it for growth. But there were other conditions that had to be right before germination could occur.

Oxygen was the main ingredient in this recipe for growth. During its long fall, the airtight seed coat prevented any gases from reaching the contents contained within, contents that — were it biological — might have been called an embryo. The Demodex mite’s digestive system, however, ravaged the seed’s protective outer sh.e.l.l, allowing oxygen to penetrate.

Unthinking, automated receptor cells measured the conditions, reacting in an exquisitely intricate biochemical dance that read like a preflight checklist;

Oxygen? Check.

Correct salinity? Check.

Appropriate humidity? Check. Suitable temperature? Check.

Billions of microscopic seeds made the long journey. Millions survived the initial fall, and thousands lasted long enough to reach a suitable environment. Hundreds landed on this particular host. Only a few dozen reached bare skin, and some of those expired before ending up in bug feces. In all, only nine germinated.

A rapid-fire growth phase ensued. Cells split via mitosis, doubling their number every few minutes, drawing energy and building blocks from the food stored within the seeds. The seedlings’ survival depended on speed — they had to sink roots and grow protection in a soon-to-be-hostile environment. The seeds did not need leaves, only a main root, which in plant embryos is called a radicle. These radicles were the seeds’ lifeline, the means by which they would tap into the new environment.

The radicle’s main task was penetrating the skin. The skin’s outermost layer — composed of cells filled with tough, fibrous keratin — formed the first obstacle. The microscopic roots grew downward, slowly but incessantly pus.h.i.+ng through this barrier and into the softer tissues beneath. One seed couldn’t break that outer layer. Its growth sputtered out, and it died.

That left eight.

Once past that obstacle, the roots quickly dug deeper, slipping beyond the epidermis, into the dermis, then through the fatty cells of the subcutaneous layer. Receptor cells measured changes in chemical content and density. Underneath the subcutaneous layer, just before the firmness of muscle, the roots began a phase change. Each of the eight roots became the center for a new organism.

The second stage ensued.

This rapid growth had depleted the seeds’ food stores. Now nothing more than used delivery vehicles, the little husks fell away. Under the skin, second-stage roots spread out. They weren’t like roots of a tree or any other plant, but more akin to little tentacles, branching out from the center, drawing oxygen, proteins, amino acids and sugars from the new environment. Like biological conveyor belts, the roots pulled these building blocks back to the new organism, fueling an explosion of cell growth. One of the seedlings ended up on the host’s face, just above the left eyebrow. This one couldn’t draw quite enough material to fuel the secondstage growth process. It simply ran out of energy. A few of the seedling’s parts kept growing, a.s.sembling, automatically drawing nutrients from the host and creating raw materials that would never be used — but for all intents and purposes this seedling ceased to be.

That left seven.

The surviving seedlings started building things. The first construct was a microscopic, free-moving thing that, if you had an electron microscope handy, looked like a hair-covered ball with two saw-toothed jaws

on one side. These jaws sliced into cell after cell, tearing open the membrane, finding the nucleus, and sucking it inside the ball. The b.a.l.l.s read raw DNA, the blueprint of our bodies, identifying the code for biological processes, for building muscle and bone, for all creation and maintenance. That’s all the DNA was to the b.a.l.l.s, really; just blueprints. Once read, the b.a.l.l.s returned this information to the seedlings.

With that data the seven knew what needed to be built in order to grow. Not at a conscious level, but at a raw, data-in and data-out machinelike state. Sentience didn’t matter — the organisms read the blueprints, and knew what to do next.

The seedlings drew sugars from the bloodstream, then fused them, a fast and simple chemical weld that created a durable, flexible building material. As the building blocks acc.u.mulated, the organisms created their next autonomous, free-moving structures. Where the b.a.l.l.s had gathered, these new microstructures built. Using the growing stores of the building material, the new structures started weaving the sh.e.l.l. Without fast sh.e.l.l growth, the new organism might not live five more days.