Modern Management of Myelomeningocele

be absent, prophesied its usefulness for selective insect control. The structures of two natural juvenile hormones from the Cecropia silkmoth, as substituted terpene derivatives, were finally reported in 1967 and 1968. This opened a frenzy of activity in juvenile hormone research involving the synthesis and testing of innumerable JH analogs and mimics. This volume, representing the proceedings of a symposium held in Washington, D.C., in September, 1971, under the sponsorship of the American Chemical Society, conveys a vignette of this contemporary activity. Many of the papers are essentially research progress reports, with detailed tabulations of data and few broad conclusions, which scarcely justify immortalization between hard covers. Nevertheless, parts of the book provide a good introduction to this field of research, and others contain data which will be valuable to those engaged in it. Schneiderman's introductory paper is distinguished for its breadth, clarity and biological insight. There follow two papers on the mechanism of action of juvenile hormone-a theoretical construct based on factors for control of transcription by Williams and Kafatos, and an experimental paper from Ilan's group supporting control at the translational level-two opposite veiwpoints which can scarcely be reconciled without further data. Riddiford's discussion of JH and embryonic development contains the remarkable observation that JH applied to certain early stages can modify the programmed activity of the corpora allata at the time of metamorphosis, weeks later; this is reminiscent of the effects of gonadal steroids in the vertebrate embryo upon subsequent nervous system activity patterns. Three contributions discuss the biological and environmental decomposition of JH and JH mimics. The remainder describe the development of JH chemistry and synthesis, and the approaches to use of JH mimics (most are not strictly analogs) for selective insect control. In the U.S. Department of Agriculture laboratories alone, tests of more than 450 compounds are reported, and this is paralleled by intense efforts in several commercial laboratories. The results are promising, and since the date of these reports still more potent substances have been synthesized. A surprising and useful aspect is that different compounds have vastly differing activities on different groups of insects. Yet, no clear relationships between chemical structure and biological activity have emerged. In contrast to these applied studies stands the small amount of research on the biochemical mechanism of action of JH-a problem of exceptional interest in view of the unusual lipid character of these hormones and their powerful effects on development and differentiation.