Three rules, no rulerWhat every filament does, ten times a second
Taste three ways
Each filament reads the pheromone trail at three points ahead — left, centre, right. That is its whole sensory world: three numbers.
Lean toward the richest
It turns a few degrees toward whichever sample is strongest, and steps forward. Stronger trail means more traffic means stronger trail.
Leave a mark, let it fade
It deposits a little scent where it lands. Every frame the whole map blurs and decays — so only routes that keep earning traffic survive.
The Tokyo experimentNakagaki et al. · Hokkaido University · 2010
Lay oat flakes where Tokyo's 36 stations sit, and the mould rebuilds the rail map.
Researchers placed food across a wet dish arranged like Greater Tokyo, then let Physarum polycephalum spread. Within a day the cell had pruned its exploratory sheet into a lean transport web — connecting every flake with a network that matched the real Japan Rail system for length, efficiency, and fault tolerance.
No blueprint. No engineer. Just a bag of protoplasm balancing two forces: reach every food source, and waste as little tube as possible. The same tension you are watching resolve on this page.
Scent — pheromone it lays and follows.
Crumb — a food source pumping scent.
Vein — a route reinforced past decay.
Everything on the plate above is one of these four. Nothing else is happening.