Birth and death among chemical blobs.

Behaving like a zoo of living cells, the spots created in a simple chemical mixture grow, divide, and when overcrowded, die. Representing little pools of low acidity in an acid bath, these spots continue their activity as long as fresh chemicals are fed into the system.

The discovery of this behavior in the laboratory represents an intriguing extension of the types of patterns observed when different, continuously supplied chemicals react and the reaction products diffuse through a gel or some other medium (SN: 5/9/92, p.311). Kyoung-Jin Lee, William D. McCormick, and Harry L. Swinney of the University of Texas at Austin describe their experiments in the May 19 [N.sub.ATURE].

"These are dynamic patterns that have not been seen before," Lee says. But there is no evidence that this chemical behavior is directly linked to any biological system.

The researchers produced the patterns in a thin, transparent gel continuously fed with a fresh solution containing sulfuric acid and iodate, sulfite, and ferrocyanide ions. Interactions among the reacting chemicals and the diffusing reaction products created well-defined regions of low acidity.

At low ferrocyanide concentrations, intricate, mazelike patterns appeared. At higher concentrations, blobs showed up, which sprouted and sloughed off new blobs. The observed patterns closely resembled those generated in earlier computer simulations of the chemical reaction, done by John E. Pearson of the Los Alamos (N.M.) National Laboratory.