The Scientist has asked a group of experts to comment periodically upon recent articles that they have found noteworthy. Their selections, presented herein every issue, are neither endorsements of content nor the result of systematic searching. Rather, the list represents personal choices of articles the columnists believe the scientific community as a whole may also find interesting. Reprints of any articles cited here may be ordered through The Genuine Article, 3501 Market St., Philadelphia,

The Scientist has asked a group of experts to comment periodically upon recent articles that they have found noteworthy. Their selections, presented herein every issue, are neither endorsements of content nor the result of systematic searching. Rather, the list represents personal choices of articles the columnists believe the scientific community as a whole may also find interesting. Reprints of any articles cited here may be ordered through The Genuine Article, 3501 Market St., Philadelphia,

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King's College London, U.K. The cycads are an unusual group of gymnosperms in that they are pollinated by insects rather than by wind. In a study of the Mexican cycad, Zamia furfuracea, pollination was found to be dependent on a single insect species, the host-specific snout weevil, which completes its entire life cycle within the cones of this plant. Hatching, feeding, mating, and oviposition all take place within the male co

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King’s College London, U.K. " A single, invasive plant species can change the structure and composition of an entire ecosystem, as is the case in Hawaii Volcanoes National Park, where the introduced tree Myrica faya is assuming dominance on the fresh volcanic soils.It grows faster than native trees, produces a seed rain of up to 60 seeds per square meter per year, and fixes nitrogen from the atmosphere at a rate 100 tim

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King’s College London, U.K Considerable debate surrounds the decline and collapse of the Central American Maya culture. The analysis of carbon and nitrogen isotopes in bones from Maya burials has now permitted some reconstruction of diet. The importance of maize has been confirmed, though it does seem to have become a less important dietary element at the time of the Maya collapse. C.D. White, H.P. Schwarcz, “Ancie

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King’s College London, U.K. " Strangler figs begin their life as epiphytes, rooted in small hollows in their host’s trunk and branches, where organic matter accumulates. These pockets of elevated soil are actually richer in nutrients than are surronding soils, so even when the figs have established ground roots they still retain some upwardly growing roots to tap this rich resource. F.E. Putz, N.M. Holbrook, R

PLANT AND ANIMAL SCIENCES By PETER D. MOORE Department of Biology Kings College London, U.L " While most experimental studies of the effect of acid rain on plants have been carried out on single species, the real world contains many species of plants in competitive juxtaposition. Experiments on white clover and rye grass show that the outcome of acid rain treatment depends on such factors as the relative density of the two species and the timing of the application of acid rain. L. Menchaca,

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King’s College London, U.K. " Many plants respond to grazing by increasing their production of secondary chemical compounds that play a deterrent role. Stinging nettles (Urtica dioica) from heavily grazed habitats are found to possess higher densities of stinging hairs than those from ungrazed areas, and experimental damage to plants in the laboratory also results in higher trichome density on the new shoots. A.S. Pullin

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King's College London, U.K. " Air pollution is known to affect the growth of many species of lichens; it also influences the genmnation of ascospores from the lichen fungal symbionts. Sulfurous acid and sodium fluoride reduced germination in all tested species, but had least effect on the pollution tolerant species Lecanora conizaeoides. The two pollutants were synergistic in effect, and they are evidently capable of restrictin

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King’s College London, U.K. " The shells of dinosaur eggs developed in a manner that more closely resembles some birds’ eggs than it does modern reptiles’ eggs. The texture changes abruptly in sequential layers as a result of organic material periodically interrupting calcite deposition. This structure is also found in the thick shells of modern rarities such as ostrich and rhea. H. Silyn-Roberts, R.M. Sharp

PLANT AND ANIMAL SCIENCES BY PETER D. MOORE Department of Biology King’s College London, U.K. " The measurement of large-scale gas exchange between the biosphere and the atmosphere is extremely necessary, but it is difficult in practice. The use of aircraft sampling with laser-based detection equipment has produced good data for carbon dioxide and ozone in stable conditions, and prospects are promising for carbon monoxide, methane, sulfur dioxide, oxides of nitrogen, and others. P.A. M

PLANT AND ANIMAL SCIENCES PETER D. MOORE Department of Biology Kings College London, U.K. " Few birds have been of greater economic importance to humanity than the chicken, yet there is still disagreement about its origin and the geographic pattern of its domestication and spread. New evidence suggests that it was first domesticated in southeast Asia and taken into China about 8,000 years ago, whence it spread to India and Europe. B. West, B.-X. Zhou, "Did chickens go north? New evidence fo