Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N
Cover image: subcircuit from a regulatory gene network is superimposed on clockwork images to impart a sense of development unfAgeding over time. Researchers have found the architecture of subcircuit elements to be similar across species, even though the genes themselves are not orthologous. See Eric Davidson and Michael Levine's introduction to the Gene Networks in Development and Evolution Special Feature on pages 20063–20066. Cover image based on design by Joel Smith (Division of Biology, California Institute of Technology, Pasadena, CA).