Five sequences illustrating the diffusion reaction also called Turing mechanism and known to generate patters in many species including fish, snails, mamals and cuttlefish, which Alan Turing studied in the 1940s and wrote a book about named "The Chemical Basis of Morphogenesis".
Dots, lines and spirals occur when certain substances (two, three or four chemicals, or, in the case of animals, pigments) with different diffusion rates and a relationship of mutual amplification and reduction meet.
In our case there are just two substances, simulated in Java, basically in two lines of code. And yet, the fifth sequence shows dark waves rolling over other, more intricate patterns much as we can see it happen on the backs of cuttlefish (if they so desire).
For more information on the algorithm see a tutorial one of the earliest software artists, Karl Sims (whose first particle animations inspired dextro.org to start its offshoot turux.org in 1997, dedicated solely to interactive animations) set up at karlsims.com/rd.html.
This video forms the fourth interlude to the ongoing video screening at the train station of Baden near Vienna, Austria, photos of which can be seen at dextro.org/oebb.