Number 80 (Story #1), May 19, 1992 by Phillip F. Schewe and Ben Stein WHERE DOES THE TIGER GET ITS STRIPES? For decades, scientists in a wide range of disciplines have strived to understand how nature generates biological patterns such as the stripes on a tiger and the rings on bees. In 1952, mathematician Alan Turing stimulated much interest in this question when he proposed that stationary patterns can be formed in chemical reactions that are mediated by diffusion processes. However, experimenters were unable to reproduce "Turing patterns" in the laboratory until last year, when Qi Ouyang and Harry Swinney at the University of Texas demonstrated 2-dimensional hexagonal arrays which resemble chicken skin. Produced by a chlorite-iodide-malonic acid (CIMA) solution which diffuses through glass disks and reacts on a gel surface, these patterns spontaneously disappear and then reappear when the system passes through a critical temperature known as the Turing bifurcation point. At the recent APS meeting in Washington, D.C., Ouyang reported how the adjustment of a single chemical component in a gel solution could result in identifiable, stationary, striped or dot patterns. Swinney admits that the demonstration of such chemical patterns does not yet prove that the Turing mechanism is responsible for biological patterns. (Science News, 9 May 1992.)