Number 9 (Story #1), November 20, 1990 by Phillip F. Schewe and Ben Stein HYPERBRANCHED MACROMOLECULES, huge tree-like molecules almost the size of a virus, can now be synthesized in the lab. Donald A. Tomalia of the Michigan Molecular Institute claims that some of his largest molecules, which he calls dendrimers (so named for their dendritic architecture), have molecular weights approaching one million units, much smaller than chromosomes (with weights in the billions), but much larger than previous molecules of comparable shape. Unlike conventional polymers, which are usually chainlike objects, the dendritic polymers resemble pom-poms. Tomalia believes that dendrimers are "molecular analogues of atoms," and that by varying dendrite growth patterns, one can create a "molecular-level periodic table." William A. Goddard at Caltech (818-356-6544) and others are studying possible uses for the molecules. (Science News, Nov. 10.)