CoachMicroorganisms — microbes — are living things too small to see unaided. The main kinds:
- bacteria: single cells without a true nucleus, far smaller than your cells, dividing fast (Definition 45.4’s world) — everywhere, in numbers beyond count;
- single-celled fungi and others: yeasts (Example 43.5), molds’ spores, the pond drop’s swimmers;
- viruses: smaller still, and different in kind — a packaged scrap of genetic text (Definition 65.4’s letters) in a coat, with no cell and no life of its own: a virus does nothing until it enters a living cell and turns that cell’s reading machinery to copying the intruder’s text. On the signs of Proposition 1.3, viruses sit at life’s very edge.
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Example 69.3 (One body, three relations)
On your skin this minute: residents by the billion, holding the surface (relation one: alliance). In your yogurt at breakfast: workers, souring on command (relation two: employment, Example 43.6). On the rusty nail in the shed: spores of the lockjaw bacterium, waiting for a deep cut (relation three: the pathogen minority, and the reason for Chapter 70 and the tetanus booster).
Example 69.5 (Two invaders, contrasted)
The cut’s bacterium against the winter’s cold virus. The bacterium: enters the breach, multiplies between cells in the warm wet tissue, its wastes poisoning the neighborhood — the throb and pus of a septic finger. The virus: rides a droplet to the airway lining, enters the lining cells themselves, and each hijacked cell releases a crowd of copies before failing — the raw throat and streaming nose of its trail. Different mechanics; the antibiotic that starves the first cannot touch the second, for the second borrows your machinery, and drugs against it are hard to aim.