Four-hourly fluctuations in grass-pollen concentrations in relation to wet versus dry weather,and to short versus long over-land advection

Four-hourly volumetric measurements of airborne grass-pollen concentrations at Leiden, near the west coast of the Netherlands, were analyzed according to wet-versus-dry meteorological conditions in the pollen source area, and according to the distance of the over-land advection to the pollen sampler. Airborne pollen concentrations appear to be low when the source surface is wet by past or present rain, fog, or dew; and high when the source area is dry. Air adverted over long over-land distances from dry source areas contains much pollen, especially in the afternoon, due to pollen release and decreasing air turbulence. High nightly pollen concentrations are observed after a warm and dry day with much pollen release in distant source areas when the nocturnal meteorological conditions stimulate concentration of pollen grains into the lower layers of the atmosphere.Presented at the Sixth International Palynological Conference, 26 August – 1 September 1984, Calgary, Canada.     

10. Na Bahně (Czech Republic): Vegetation development over the last 2.5 millennia in the Eastern Bohemian lowland

To determine the best date for patients in the southern part of the Netherlands to begin treatment for pollinosis, an attempt was made to predict the start of the grass pollen season at Helmond as accurately as possible, as was previously done at Leiden. The start of the grass pollen season was defined as the date when at a given location the accumulated total (from 1 Jan.) of 24 h average grass pollen concentrations (No./m³) reaches 100 (the so-called Σ100-method). Using the phenological method over the years 1981 through 1985, with the birch (Σ125=x) as the indicator plant, the start of the grass pollen period (Σ100=z) could be predicted much more accurately than would have been possible solely on the basis of the mean starting dates in the preceding years. The predicted starting date (z) can be calculated with the equation z=0.44x+95.46 (x and z as day-of-year numbers), SD=3.6 days, r=0.83, n=5). The SD of the Σ100-method of grasses being 5.6 days, the effectivity of the prediction is 35.7%. The difference in results between Helmond and Leiden is discussed.     

For the Sake of Our Future: Sacrificing in Eastern Indonesia

For tfie Sake of Our Future: Sacrificing in Eastern Indonesia. Signe Howell. ed. Leiden, Netherlands: Leiden University, 1996. 398 pp.     

Evolutionary dynamics of declining melanism in the peppered moth in the Netherlands

Populations of Biston betularia in the region of The Netherlands around Leiden and Rotterdam were resampled. A comparison of three sets of data for 1969-1973, 1988 and 1999 enabled a further examination of declines in melanism. Unlike parallel changes for the black carbonaria form of this species in urban regions of Britain, those inThe Netherlands involve substantial changes in frequencies of at least two of the intermediate insularia morphs as well as an increase in the non-melanic typica morph. The darkest of the three insularia morphs has shown a transitory pulse of increased frequency in The Netherlands. The dynamics are discussed in relation to the history of air pollution and to straightforward predictions about selection.     

The Earliest Occupation of Europe

The Earliest Occupation of Europe. Wil Roebroeks and Thys Van Kolfschoten. eds. Leiden, Netherlands: University of Leiden, 1995. 332 pp.     

Technical Information Sheet No. 13: Simple storage of plant cell cultures in liquid media

H.M. Schumacher and K.A. Malik are with DSM-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1 B, 38124 Braunschweig, Germany; F. Van Iren is with the Institute of Molecular Plant Sciences, Leiden University, Wassenaarseweg 64, NL 2333 AL Leiden, The Netherlands.     

Redescription of Amblyomma fuscum Neumann, 1907 (Acari: Ixodidae), a rare South America tick confirmed in Brazil

The species Amblyomma fuscum Neumann, 1907 is a rare tick found on the Neotropical Region, but it has not been recorded as a valid taxon in some lists proposed by current taxonomists. After a comparison between the Brazilian material of A. fuscum deposited in the Acari Collection of the Butantan Institute, São Paulo, Brazil, and the male type deposited in Leiden Museum of Natural History, The Netherlands, we confirm the taxonomic validity of A. fuscum and redescribe the adult specimens based on light and scanning electron microscope studies.     

Triatominae species of Suriname (Heteroptera: Reduviidae) and their role as vectors of Chagas disease

Nine species of Triatominae, representing three tribes and five genera, are currently known in Suriname. An annotated list of the species based on the collections of the Bureau of Public Health (Suriname), the National Zoological Collection Suriname and the National History Museum Leiden (the Netherlands) is provided. Additionally, the results of several years of opportunistic collection in two domestic environments are presented. The most common species are Rhodnius pictipes Stål, 1972, Rhodnius robustus Larrouse, 1972 and Panstrongylus geniculatus (Latreille, 1811). The significance of the species as vectors of Chagas disease in Suriname is discussed.     

Outward Appearances: Dressing State and Society in Indonesia

Outward Appearances: Dressing State and Society in Indonesia. Henk Schulte Nordholt. ed. Leiden, Netherlands: KITLV Press, 1997. 327 pp.     

Central African Hunter-Gatherers in a Multidisciplinary Perspective: Challenging Elusiveness

Central African Hunter-Gatherers in. Multidisciplinary Perspective: Challenging Elusiveness. Karen Biesbrouck. Stefan Elders. and Gerda Rossel. eds. Leiden, the Netherlands: CNWS Publications, 1999. 331 pp.     

Clinical trial update II

The second Clinical Trial Update session was chaired by J.J. Bax (Leiden, the Netherlands) and J. Brugada Terradellas (Barcelona, SpRole). In particular, four trials provided interesting information.     

Some Flore Pleno Specimens gathered in the Netherlands in 1678 by John Snodgrass

Summary

On folio sheets bound as a book are some 850 pressed specimens gathered in 1678 from the Leiden Botanical Garden and elsewhere in the Netherlands by the Scottish medical student John Snodgrass. There are not less than 20 flore pleno species from several families including Brassicaceae (Cheiranthus, Matthiola), Liliaceae (Frilillaria), Ranunculaceae (Anemone, Aquilegia, Caliha, Hepatica, Ranunculus) and Rosaceae (Prunus, Rosa).     

Mutation Research: the origin

This brief commentary reflects on the founding of the journal Mutation Research. It includes a photograph of the participants in the scientific conference held in 1962 at the University of Leiden, The Netherlands, at which Professor F.H. Sobels proposed the establishment of the Journal.     

Animal migration: linking models and data beyond taxonomic limits

An international workshop on animal migration was held at the Lorentz Center in Leiden, The Netherlands, 2–6 March 2009, bringing together leading theoreticians and empiricists from the major migratory taxa, aiming at the identification of cutting-edge questions in migration research that cross taxonomic borders.     

Sacrifice of Serpents: The Festival of Indrayani in Kathmandu

Sacrifice of Serpents: The Festival of Indrayani in Kathmandu. 1997. 108 minutes, color. video by Dirk Nijland. Balgopal Shresiha. and Bert Van Den Hoek. Institute of Cultural and Social Studies, Film Library, Wassenaarseweg 52, 2333 AK Leiden, The Netherlands.     

Numerical analysis study of pollen grain populations of Eryngium Maritimum L. (Umbelliferae)

Statistical and numerical taxonomic methods reveal two groups of pollen populations in one plant of Eryngium maritimum L. growing at Noordwijk aan Zee (The Netherlands); one group includes the tertiary and primary lateral inflorescences which possess inhibited growth; the other group comprises the secondary lateral inflorescences showing normal growth. The effects of the physiological inhibition mechanism are complex and are shown by many pollen characters— the dimensions of P (polar axis) and E (equatorial diameter), the presence of a thickening of the exine in the intermediate zone, the shape of the internal contour of the endexine, etc. The differentiation of two types of pollen populations has not only taxonomic interest at the individual, locality, or species level, but also physiological significance. The shape of the internal contour of the endexine, which is a very important feature of “macroevolution” of pollen types in Umbelliferae (Cerceau-Larrival), is directly influenced by the inhibited growth.     

The classification of disciplines in biology: A plea for pluralism

Pluralism is a sound strategy in classifying disciplines of biology. The relevance of a particular classification depends on various methodological issues, on the way in which the scientist's problems are specified, and on factual matters.Lecture presented before the Netherlands Society for Theoretical Biology, Leiden, 14 March 1975.     

Correlation analysis between some blood properties and atmospheric environmental parameters

S.W. Tromp made investigations of a weather effect on erythrocyte sedimentation rates (ESR) of human blood by routine checks of the blood of donor groups in Leiden from 1955 to 1985. A higher ESR was found for the summer season and lower ESR for winter and low values occurred soon after a strong cooling spell. In this report, we have continued his work using data for the years 1971–1985 from Leiden (The Netherlands). An influence of the weather on ESR was also found, but this seems to be more complicated than Tromp supposed. Some new aspects are described and elaborated, e.g. ESR already increases before warming is noticed at the ground layer. This is possibly caused by changes in the upper atmosphere, a suggestion that requires further studies. For periods of low ESR, there was a greater number of occlusion fronts passing the Netherlands. The long-term fluctuations of ESR that were found were correlated with sun spot relative numbers only in a few periods. The results of our study justify further research for a variety of other locations around the world.     

BOOK REVIEW

Zoologia Neocaledonica. Volume I. S. Tillier (Ed.). Mémoires du Muséum National d'Histoire Naturelle (Zoologie). Tome 142. Paris. 1988. 158 pp. 79 Guilders. Overseas orders to: E.J. Brill, P.O. Box 9000, 23000 PA Leiden, The Netherlands.     

The Diet and Reproductive Schedules of Leptonycteris curasoae curasoae and Glossophaga longirostris elongata (Chiroptera: Glossophaginae) on Curaçao

Two bat species, Leptonyrteris curasoae and Glossophaga longirostris, are the principal pollinators of at least two of the three species of columnar cacti that grow on the semiarid island of Curaçao, Netherlands Antilles. I examined the importance of the cacti in the diets of the bats and found that 85–91 percent of their diet samples contained cactus pollen and seeds. At least 43 percent of the samples from each species contained cactus pollen andlor seeds exclusively. Leptonycteris curasoae consumes nectar and pollen of Ceiba pentandra and Agave spp. at the beginning of the dry season and G. longirostris also consumes a few other plant products in the wet season, but both bat species depend nutritionally on cacti. Female bats give birth to one pup per year, and the periods of parturition and lactation in each species correspond to peaks in the reproductive phenology of the two most abundant columnar cactus species. From personal observations and a review of the literature, I determined that bats were unlikely to fly to the mainland to feed, although L. curasoae may do so. I conclude that the interdependence of bats and cacti is suggestive of coevolution, and that columnar cacti are critical for the survival and persistence of nectar-feeding bats on Curaçao.