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.
Examples
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.